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Sample records for stress concentration effects

  1. Stress concentration effects in high pressure components

    International Nuclear Information System (INIS)

    Aller, J.E.

    1990-01-01

    This paper examines the stress concentration effects of sideholes in thick walled, high pressure cylinders. It has been shown that the theoretical stress concentration factor at the intersection of a small crossbore in a closed end, thick walled cylinder varies between 3.0 and 4.0. Tests have shown that this effect can be greatly reduced in practice by carefully radiusing the bore intersection and autofrettaging the cylinder. It has also been shown that the minimum stress concentration factor occurs when the main bore and sidehole or crossbore have the same diameter, and the radius of the intersection is approximately equal to the sidehole radius. When the bore and sidehole intersection angle decreases from 90 degrees, the stress concentration factor increases significantly. Knowledge of these fundamental relationships can be used in maintaining, as well ad designing, high pressure equipment

  2. Effects of stress concentration on low-temperature fracture behavior of A356 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Guanghui; Li, Runxia; Li, Rongde

    2016-06-14

    The effect of stress concentration on the dislocation motion, the Si particles and the crack propagation path in A356 alloy at the temperature of 20 °C to −60 °C was analyzed by scanning electron microscope and optical microscope using a series of notched tensile specimens and normal tensile specimens. The results show that the sensitivity of A356 alloy to the stress concentration increases, the tensile strength and yield strength of normal specimens and notched specimens increase, and the elongation shows a decreasing trend with the decrease of test temperature from 20 °C to −60 °C. The yield strength is not affected by the notch, and the tensile strength is sensitive to the stress concentration. Stress concentration leads to a large number of dislocation generation. Local plastic deformation occurred in the stress concentration region during the tensile process firstly. With the stress concentration in the aluminum matrix between the Si phase and the crack further increasing, the distribution of cracks along the Si phase leads to the cracking of aluminum matrix particle.

  3. Effects of high concentration of chromium stress on physiological ...

    African Journals Online (AJOL)

    We studied the effects of high concentration of chromium (Cr) stress on physiological and biochemical characters and accumulation of Cr in Pingyang Tezao tea [Camellia sinensis (L) O. Kutze 'Pingyangtezao'] through a pot experiment. The results show that the indicators of photosynthesis were all suppressed with ...

  4. Effect of Electrical Discharge Machining on Stress Concentration in Titanium Alloy Holes.

    Science.gov (United States)

    Hsu, Wei-Hsuan; Chien, Wan-Ting

    2016-11-24

    Titanium alloys have several advantages, such as a high strength-to-weight ratio. However, the machinability of titanium alloys is not as good as its mechanical properties. Many machining processes have been used to fabricate titanium alloys. Among these machining processes, electrical discharge machining (EDM) has the advantage of processing efficiency. EDM is based on thermoelectric energy between a workpiece and an electrode. A pulse discharge occurs in a small gap between the workpiece and electrode. Then, the material from the workpiece is removed through melting and vaporization. However, defects such as cracks and notches are often detected at the boundary of holes fabricated using EDM and the irregular profile of EDM holes reduces product quality. In this study, an innovative method was proposed to estimate the effect of EDM parameters on the surface quality of the holes. The method combining the finite element method and image processing can rapidly evaluate the stress concentration factor of a workpiece. The stress concentration factor was assumed as an index of EDM process performance for estimating the surface quality of EDM holes. In EDM manufacturing processes, Ti-6Al-4V was used as an experimental material and, as process parameters, pulse current and pulse on-time were taken into account. The results showed that finite element simulations can effectively analyze stress concentration in EDM holes. Using high energy during EDM leads to poor hole quality, and the stress concentration factor of a workpiece is correlated to hole quality. The maximum stress concentration factor for an EDM hole was more than four times that for the same diameter of the undamaged hole.

  5. A Study on Effect of Local Wall Thinning in Carbon Steel Elbow Pipe on Elastic Stress Concentration

    International Nuclear Information System (INIS)

    Kim, Jong Sung; Seo, Jae Seok

    2009-01-01

    Feeder pipes that connect the inlet and outlet headers to the reactor core in CANDU nuclear power plants are considered as safety Class 1 piping items. Therefore, fatigue of feeder pipes should be assessed at design stage in order to verify structural integrity during design lifetime. In accordance with the fatigue assessment result, cumulative usage factors of some feeder pipes have significant values. The feeder pipes made of SA-106 Grade B or C carbon steel have some elbows and bends. An active degradation mechanism for the carbon steel outlet feeder piping is local wall thinning due to flow-accelerated corrosion. Inspection results from plants and metallurgical examinations of removed feeders indicated the presence of localized thinning in the vicinity of the welds in the lower portion of outlet feeders, such as Grayloc hub-to-bend weld, Grayloc hub-to-elbow weld, elbow-to-elbow, and elbow-to-pipe weld. This local wall thinning can cause increase of peak stress due to stress concentration by notch effect. The increase of peak stress results in increase of cumulative usage factor. However, present fatigue assessment doesn't consider the stress concentration due to local wall-thinning. Therefore, it is necessary to assess the effect of local wall thinning on stress concentration. This study investigates the effect of local wall thinning geometry on stress concentration by performing finite element elastic stress analysis

  6. Stress concentration factors for pressurized elliptic crossbores in blocks

    International Nuclear Information System (INIS)

    Badr, Elie A.

    2006-01-01

    Intersecting bore geometries are used in a number of industrial applications including heavy-walled pressure vessels containing oil holes for lubrication, ports for valves and fluid ends of reciprocating pumps. The bore intersection location is a stress concentration point where the maximum hoop stress can be many times the fluid pressure in the bores. Intersecting circular holes in heavy-walled cylinders and rectangular blocks have been extensively investigated. Specifically, stress/pressure concentration curves for intersecting circular bores in rectangular blocks were presented by Sorem et al. [Sorem JR, Shadley JR, Tipton SM. Design curves for maximum stresses in blocks containing pressurized bore intersections. ASME J Mech Des 1990; 113: 427-31.]. However, stress/pressure concentrations due to intersecting elliptic bores have not been broadly investigated. With the availability of computer numerical control (CNC) machinery, bores with elliptic crosssection can be produced with relative ease. In this paper, hoop stress concentration ratios are developed for elliptic crossbores in rectangular blocks. Results indicate that introducing elliptic crossbores, rather than circular ones, significantly reduces the hoop stress concentration factor at the crossbore intersection. Also, the presence of intersecting crossbores has a major effect on the fatigue life of pressure vessels [Badr EA, Sorem JR, Jr Tipton SM. Evaluation of the autofrettage effect on fatigue lives of steel blocks with crossbores using a statistical and a strain-based method. ASTM J Test Eval 2000; 28: 181-8.] and the reduction of hoop stress concentration is expected to enhance the fatigue life of pressure vessels containing crossbores

  7. [Effects of short-term elevated CO2 concentration and drought stress on the rhizosphere effects of soil carbon, nitrogen and microbes of Bothriochloa ischaemum.

    Science.gov (United States)

    Xiao, Lie; Liu, Guo Bin; Li, Peng; Xue, Sha

    2017-10-01

    A water control pot experiment was conducted in climate controlled chambers to study soil carbon, nitrogen and microbial community structure and their rhizosphere effects in the rhizosphere and non rhizosphere soil of Bothriochloa ischaemum at elevated CO2 concentrations (800 μmol·mol -1 ) under three water regimes, i.e., well watered (75%-80% of field capacity, FC), moderate drought stress (55%-60% of FC), and severe drought stress (35%-40% of FC). The results showed that elevated CO2 concentration and drought stress did not have significant impacts on the content of soil organic carbon, total nitrogen or dissolved organic carbon (DOC) in the rhizosphere and bulk soils or their rhizosphere effects. Elevated CO2 concentration significantly decreased dissolved organic nitrogen (DON) content in the rhizosphere soil under moderate drought stress, increased DOC/DON, and significantly increased the negative rhizosphere effect of DON and positive rhizosphere effect of DOC/DON. Drought stress and elevated CO2 concentration did not have significant impacts on the rhizosphere effect of total and bacterial phospholipid fatty acids (PLFA). Drought stress under elevated CO2 concentration significantly increased the G + /G - PLFA in the rhizosphere soil and decreased the G + /G - PLFA in the bulk soil, so its rhizosphere effect significantly increased, indicating that the soil microbial community changed from chemoautotroph microbes to heterotrophic microbes.

  8. PREDICTION OF STRESS CONCENTRATION FACTORS IN

    African Journals Online (AJOL)

    ES OBE

    consider the effect of brace spacing on strengths of tubular K joints without consideration of same effect on square section K Joints. This lack of studies design strengths of gapped square section K joints makes availability of information on stress concentration factors in same joints scarce. However, information on 'Hot Spot' ...

  9. Effect of Abiotic Stresses on the Nondestructive Estimation of Rice Leaf Nitrogen Concentration

    Directory of Open Access Journals (Sweden)

    Stephan M. Haefele

    2010-01-01

    Full Text Available Decision support tools for non-destructive estimation of rice crop nitrogen (N status (e.g., chlorophyll meter [SPAD] or leaf color chart [LCC] are an established technology for improved N management in irrigated systems, but their value in rainfed environments with frequent abiotic stresses remains untested. Therefore, we studied the effect of drought, salinity, phosphorus (P deficiency, and sulfur (S deficiency on leaf N estimates derived from SPAD and LCC measurements in a greenhouse experiment. Linear relations between chlorophyll concentration and leaf N concentration based on dry weight (Ndw between SPAD values adjusted for leaf thickness and Ndw and between LCC scores adjusted for leaf thickness and Ndw could be confirmed for all treatments and varieties used. Leaf spectral reflectance measurements did not show a stress-dependent change in the reflectance pattern, indicating that no specific element of the photosynthetic complex was affected by the stresses and at the stress level applied. We concluded that SPAD and LCC are potentially useful tools for improved N management in moderately unfavorable rice environments. However, calibration for the most common rice varieties in the target region is recommended to increase the precision of the leaf N estimates.

  10. Effects of stress concentrations on the fatigue life of a gamma based titanium aluminide

    International Nuclear Information System (INIS)

    Trail, S.J.; Bowen, P.

    1995-01-01

    S-N curves for a gamma based titanium aluminide alloy of composition Ti-47.2Al-2.1Mn-1.9Nb(at.%)+2TiB 2 (wt.%) have been used to define fatigue life. Effects of residual stress, stressed volume, loading ratio, loading mode, elevated temperature and surface roughness have been considered. Residual tensile stresses and micro-cracking are introduced by Electro Discharge Machining and the fatigue life is reduced slightly compared with polished samples. Notched fatigue tests show a significant notch strengthening effect which increases with increasing stress concentration factor. The fracture surfaces of specimens tested at room temperature reveal fully brittle failure mechanisms and no evidence of stable crack growth is observed. The fatigue life appears, therefore, to be determined predominantly by the number of cycles to crack initiation. At the elevated temperature of 830 C, evidence for some stable fatigue crack growth has been found. Probable sites for crack initiation are addressed

  11. Imaging shear stress distribution and evaluating the stress concentration factor of the human eye

    Science.gov (United States)

    Joseph Antony, S.

    2015-03-01

    Healthy eyes are vital for a better quality of human life. Historically, for man-made materials, scientists and engineers use stress concentration factors to characterise the effects of structural non-homogeneities on their mechanical strength. However, such information is scarce for the human eye. Here we present the shear stress distribution profiles of a healthy human cornea surface in vivo using photo-stress analysis tomography, which is a non-intrusive and non-X-ray based method. The corneal birefringent retardation measured here is comparable to that of previous studies. Using this, we derive eye stress concentration factors and the directional alignment of major principal stress on the surface of the cornea. Similar to thermometers being used for monitoring the general health in humans, this report provides a foundation to characterise the shear stress carrying capacity of the cornea, and a potential bench mark for validating theoretical modelling of stresses in the human eye in future.

  12. Minimization of stress concentration factor in cylindrical pressure vessels with ellipsoidal heads

    International Nuclear Information System (INIS)

    Magnucki, K.; Szyc, W.; Lewinski, J.

    2002-01-01

    The paper presents the problem of stress concentration in a cylindrical pressure vessel with ellipsoidal heads subject to internal pressure. At the line, where the ellipsoidal head is adjacent to the circular cylindrical shell, a shear force and bending moment occur, disturbing the membrane stress state in the vessel. The degree of stress concentration depends on the ratio of thicknesses of both the adjacent parts of the shells and on the relative convexity of the ellipsoidal head, with the range for radius-to-thickness ratio between 75 and 125. The stress concentration was analytically described and, afterwards, the effect of these values on the stress concentration ratio was numerically examined. Results of the analysis are shown on charts

  13. Differential concentration-specific effects of caffeine on cell viability, oxidative stress, and cell cycle in pulmonary oxygen toxicity in vitro

    International Nuclear Information System (INIS)

    Tiwari, Kirti Kumar; Chu, Chun; Couroucli, Xanthi; Moorthy, Bhagavatula; Lingappan, Krithika

    2014-01-01

    Highlights: • Caffeine at 0.05 mM decreases oxidative stress in hyperoxia. • Caffeine at 1 mM decreases cell viability, increases oxidative stress in hyperoxia. • Caffeine at 1 but not 0.05 mM, abrogates hyperoxia-induced G2/M arrest. - Abstract: Caffeine is used to prevent bronchopulmonary dysplasia (BPD) in premature neonates. Hyperoxia contributes to the development of BPD, inhibits cell proliferation and decreases cell survival. The mechanisms responsible for the protective effect of caffeine in pulmonary oxygen toxicity remain largely unknown. A549 and MLE 12 pulmonary epithelial cells were exposed to hyperoxia or maintained in room air, in the presence of different concentrations (0, 0.05, 0.1 and 1 mM) of caffeine. Caffeine had a differential concentration-specific effect on cell cycle progression, oxidative stress and viability, with 1 mM concentration being deleterious and 0.05 mM being protective. Reactive oxygen species (ROS) generation during hyperoxia was modulated by caffeine in a similar concentration-specific manner. Caffeine at 1 mM, but not at the 0.05 mM concentration decreased the G2 arrest in these cells. Taken together this study shows the novel funding that caffeine has a concentration-specific effect on cell cycle regulation, ROS generation, and cell survival in hyperoxic conditions

  14. Differential concentration-specific effects of caffeine on cell viability, oxidative stress, and cell cycle in pulmonary oxygen toxicity in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, Kirti Kumar; Chu, Chun; Couroucli, Xanthi; Moorthy, Bhagavatula; Lingappan, Krithika, E-mail: lingappa@bcm.edu

    2014-08-08

    Highlights: • Caffeine at 0.05 mM decreases oxidative stress in hyperoxia. • Caffeine at 1 mM decreases cell viability, increases oxidative stress in hyperoxia. • Caffeine at 1 but not 0.05 mM, abrogates hyperoxia-induced G2/M arrest. - Abstract: Caffeine is used to prevent bronchopulmonary dysplasia (BPD) in premature neonates. Hyperoxia contributes to the development of BPD, inhibits cell proliferation and decreases cell survival. The mechanisms responsible for the protective effect of caffeine in pulmonary oxygen toxicity remain largely unknown. A549 and MLE 12 pulmonary epithelial cells were exposed to hyperoxia or maintained in room air, in the presence of different concentrations (0, 0.05, 0.1 and 1 mM) of caffeine. Caffeine had a differential concentration-specific effect on cell cycle progression, oxidative stress and viability, with 1 mM concentration being deleterious and 0.05 mM being protective. Reactive oxygen species (ROS) generation during hyperoxia was modulated by caffeine in a similar concentration-specific manner. Caffeine at 1 mM, but not at the 0.05 mM concentration decreased the G2 arrest in these cells. Taken together this study shows the novel funding that caffeine has a concentration-specific effect on cell cycle regulation, ROS generation, and cell survival in hyperoxic conditions.

  15. Coupling effects of chemical stresses and external mechanical stresses on diffusion

    International Nuclear Information System (INIS)

    Xuan Fuzhen; Shao Shanshan; Wang Zhengdong; Tu Shantung

    2009-01-01

    Interaction between diffusion and stress fields has been investigated extensively in the past. However, most of the previous investigations were focused on the effect of chemical stress on diffusion due to the unbalanced mass transport. In this work, the coupling effects of external mechanical stress and chemical stress on diffusion are studied. A self-consistent diffusion equation including the chemical stress and external mechanical stress gradient is developed under the framework of the thermodynamic theory and Fick's law. For a thin plate subjected to unidirectional tensile stress fields, the external stress coupled diffusion equation is solved numerically with the help of the finite difference method for one-side and both-side charging processes. Results show that, for such two types of charging processes, the external stress gradient will accelerate the diffusion process and thus increase the value of concentration while reducing the magnitude of chemical stress when the direction of diffusion is identical to that of the stress gradient. In contrast, when the direction of diffusion is opposite to that of the stress gradient, the external stress gradient will obstruct the process of solute penetration by decreasing the value of concentration and increasing the magnitude of chemical stress. For both-side charging process, compared with that without the coupling effect of external stress, an asymmetric distribution of concentration is produced due to the asymmetric mechanical stress field feedback to diffusion.

  16. Effect of Heat Stress on Concentrations of Faecal Cortisol Metabolites in Dairy Cows.

    Science.gov (United States)

    Rees, A; Fischer-Tenhagen, C; Heuwieser, W

    2016-06-01

    The negative impact of heat stress on health and productivity of dairy cows is well known. Heat stress can be quantified with the temperature-humidity index (THI) and is defined as a THI ≥ 72. Additionally, animal welfare is affected in cows living under heat stress conditions. Finding a way to quantify heat stress in dairy cows has been of increasing interest over the past decades. Therefore, the objective of this study was to evaluate concentrations of faecal glucocorticoid metabolites [i.e. 11,17-dioxoandrostanes (11,17-DOA)] as an indirect stress parameter in dairy cows without heat stress (DOA 0), with heat stress on a single day (acute heat stress, DOA 1) or with more than a single day of heat stress (chronic heat stress, DOA 2). Cows were housed in five farms under moderate European climates. Two statistical approaches (approach 1 and approach 2) were assessed. Using approach 1, concentrations of faecal 11,17-DOA were compared among DOA 0, DOA 1 and DOA 2 samples regardless of their origin (i.e. cow, unpaired comparison with a one-way anova). Using approach 2, a cow was considered as its own control; that is 11,17-DOA was treated as a cow-specific factor and only paired samples were included in the analysis for this approach (paired comparison with t-tests). In approach 1 (p = 0.006) and approach 2 (p = 0.038), 11,17-DOA values of cows under acute heat stress were higher compared to those of cows without heat stress. Our results also indicate that acute heat stress has to be considered as a confounder in studies measuring faecal glucocorticoid metabolites in cows to evaluate other stressful situations. © 2016 Blackwell Verlag GmbH.

  17. Effect of nitrogen concentration and temperature on the critical resolved shear stress and strain rate sensitivity of vanadium

    International Nuclear Information System (INIS)

    Rehbein, D.K.

    1980-08-01

    The critical resolved shear stress and strain rate sensitivity were measured over the temperature range from 77 to 400 0 K for vanadium-nitrogen alloys containing from 0.0004 to 0.184 atom percent nitrogen. These properties were found to be strongly dependent on both the nitrogen concentration and temperature. The following observations were seen in this investigation: the overall behavior of the alloys for the temperature and concentration range studied follows a form similar to that predicted; the concentration dependence of the critical resolved shear stress after subtracting the hardening due to the pure vanadium lattice obeys Labusch's c/sup 2/3/ relationship above 200 0 K and Fleischer's c/sup 1/2/ relationship below 200 0 K; the theoretical predictions of Fleischer's model for the temperature dependence of the critical resolved shear stress are in marked disagreement with the behavior found; and the strain rate sensitivity, par. delta tau/par. deltaln γ, exhibits a peak at approximately 100 0 K that decreases in height as the nitrogen concentration increases. A similar peak has been observed in niobium by other investigators but the effect of concentration on the peak height is quite different

  18. Stress Concentration Factor and Stress Intensity Factor with U-notch and Crack in the Beam

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Bo Seong; Lee, Kwang Ho [Kyungpook National Univ., Daegu (Korea, Republic of)

    2016-05-15

    The stress concentration factors and stress intensity factors for a simple beam and a cantilever are analyzed by using finite element method and photoelasticity. Using the analyzed results, the estimated graphs on stress concentration factors and stress intensity factors are obtained. To analyze stress concentration factors of notch, the dimensionless notch length H(height of specimen)/h=1.1-2 and dimensionless gap space r(radius at the notch tip)/h=0.1~0.5 are used, where h=H-c and c is the notch length. As the notch gap length increases and the gap decreases, the stress concentration factors increase. Stress concentration factors of a simple beam are greater than those of a cantilever beam. However, actually, the maximum stress values under a load, a notch length and a gap occur more greatly in the cantilever beam than in the simple beam. To analyze stress intensity factors, the normalized crack length α(crack length)/H=0.2~0.5 is used. As the length of the crack increases, the normalized stress intensity factors increase. The stress intensity factors under a constant load and a crack length occur more greatly in the cantilever beam than in the simple beam.

  19. Crack initiation criteria for singular stress concentrations Part I: A universal assessment of singular stress concentrations

    Czech Academy of Sciences Publication Activity Database

    Knésl, Zdeněk; Klusák, Jan; Náhlík, Luboš

    2007-01-01

    Roč. 14, č. 6 (2007), s. 399-408 ISSN 1802-1484 R&D Projects: GA ČR(CZ) GA101/05/0320; GA ČR GA101/05/0227 Institutional research plan: CEZ:AV0Z20410507 Keywords : fracture mechanics * stability criteria * singular stress concentrations * crack initiation * critical stress Subject RIV: JL - Materials Fatigue, Friction Mechanics

  20. EFFECT OF ACUTE STRESS ON PLASMA CONCENTRATIONS OF SEX AND STRESS HORMONES IN JUVENILE ALLIGATORS LIVING IN CONTROL AND CONTAMINATED LAKES

    Science.gov (United States)

    Environmental contaminants can act as stressors, inducing elevated circulating concentrations of stress hormones such as corticosterone and cortisol. Development in contaminated eggs has been reported to modify circulating sex steroid hormone concentrations in alligators (Alligat...

  1. Stress concentration at notches

    CERN Document Server

    Savruk, Mykhaylo P

    2017-01-01

    This book compiles solutions of linear theory of elasticity problems for isotropic and anisotropic bodies with sharp and rounded notches. It contains an overview of established and recent achievements, and presents the authors’ original solutions in the field considered with extensive discussion. The volume demonstrates through numerous, useful examples the effectiveness of singular integral equations for obtaining exact solutions of boundary problems of the theory of elasticity for bodies with cracks and notches. Incorporating analytical and numerical solutions of the problems of stress concentrations in solid bodies with crack-like defects, this volume is ideal for scientists and PhD students dealing with the problems of theory of elasticity and fracture mechanics. Stands as a modern and extensive compendium of solutions to the problems of linear theory of elasticity of isotropic and anisotropic bodies with sharp and rounded notches; Adopts a highly reader-friendly layout of tables, charts, approximation ...

  2. Stress Concentration around Holes in Anistropic Sheets

    DEFF Research Database (Denmark)

    Krenk, Steen

    1979-01-01

    The formulation of stress concentration problems of plane anisotropic elasticity in terms of integral equations is discussed. First the singular solutions of a concentrated force and a dislocation are formulated so that they remain valid in the case of double roots. The distribution of singularit...

  3. Optimization of bolt thread stress concentrations

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard

    2013-01-01

    Designs of threaded fasteners are controlled by different standards, and the number of different thread definitions is large. The most commonly used thread is probably the metric ISO thread, and this design is therefore used in the present paper. Thread root design controls the stress concentration...... are found in the optimized designs leading to the proposal of a new standard. The reductions in the stress are achieved by rather simple changes made to the cutting tool....

  4. Numerical Analysis of Stress Concentration in Isotropic and Laminated Plates with Inclined Elliptical Holes

    Science.gov (United States)

    Khechai, Abdelhak; Tati, Abdelouahab; Belarbi, Mohamed Ouejdi; Guettala, Abdelhamid

    2018-03-01

    The design of high-performance composite structures frequently includes discontinuities to reduce the weight and fastener holes for joining. Understanding the behavior of perforated laminates is necessary for structural design. In the current work, stress concentrations taking place in laminated and isotropic plates subjected to tensile load are investigated. The stress concentrations are obtained using a recent quadrilateral finite element of four nodes with 32 DOFs. The present finite element (PE) is a combination of two finite elements. The first finite element is a linear isoparametric membrane element and the second is a high precision Hermitian element. One of the essential objectives of the current investigation is to confirm the capability and efficiency of the PE for stress determination in perforated laminates. Different geometric parameters, such as the cutout form, sizes and cutout orientations, which have a considerable effect on the stress values, are studied. Using the present finite element formulation, the obtained results are found to be in good agreement with the analytical findings, which validates the capability and the efficiency of the proposed formulation. Finally, to understand the material parameters effect such as the orientation of fibers and degree of orthotropy ratio on the stress values, many figures are presented using different ellipse major to minor axis ratio. The stress concentration values are considerably affected by increasing the orientation angle of the fibers and degree of orthotropy.

  5. Study on fatigue strength of specimens with stress concentrators accounting for inelastic cyclic strains

    International Nuclear Information System (INIS)

    Troshchenko, V.T.; Khamaza, L.A.; Mishchenko, Yu.D.

    1978-01-01

    A possibility of plotting the fatigue curves for structural elements with stress concentrators was examined according to the results of testing smooth specimens made of 1Kh2M steel. The technique has been suggested, based on using the Neuber formula, while taking into account the dependence of the effective coefficient of stresses concentration on the number of cycles prior to failure. A good agreement between the calculated and the experimental data has been obtained

  6. Blood Biochemistry and Plasma Corticosterone Concentration in Broiler Chickens Under Heat Stress

    Directory of Open Access Journals (Sweden)

    Elvis Alexander Díaz López

    2014-07-01

    Full Text Available High ambient temperatures cause susceptibility to heat stress in broiler chickens, generating metabolic changes. This paper seeks to determine the changes in blood biochemistry and plasma corticosterone concentration, as well as in glucose, total protein, albumin, globulin, sodium, chlorine, potassium, magnesium, phosphorus, and calcium in broiler chickens under chronic heat stress and at ambient temperature conditions at the Colombian Amazonian piedmont. 21-days-old male chickens of two lines were studied, distributed in an unrestricted random design, in a two-factor scheme, with four treatments. Five repetitions per treatment were performed, and 25 animals per experimental unit examined. Broilers were fed a basic diet of corn and soybean meal with 3,100 kcal ME and 19.5% protein until they reached 42 days of age. The line factor had no effect on the evaluated variables (p ≥ 0.05. However, there was statistically significant difference (p ≤ 0.05 in all variables when concentrations of metabolites in broilers under chronic heat stress were compared to those of chickens exposed to ambient temperatures at the Colombian Amazon piedmont. In conclusion, blood biochemistry suffered significant changes under both experimental temperatures, with more physiological detriment in broilers under chronic heat stress. Concentration of corticosterone became the most sensitive and consistent indicator of the physiological condition of chronic heat stress.

  7. Geometrically Nonlinear Shell Analysis of Wrinkled Thin-Film Membranes with Stress Concentrations

    Science.gov (United States)

    Tessler, Alexander; Sleight, David W.

    2006-01-01

    Geometrically nonlinear shell finite element analysis has recently been applied to solar-sail membrane problems in order to model the out-of-plane deformations due to structural wrinkling. Whereas certain problems lend themselves to achieving converged nonlinear solutions that compare favorably with experimental observations, solutions to tensioned membranes exhibiting high stress concentrations have been difficult to obtain even with the best nonlinear finite element codes and advanced shell element technology. In this paper, two numerical studies are presented that pave the way to improving the modeling of this class of nonlinear problems. The studies address the issues of mesh refinement and stress-concentration alleviation, and the effects of these modeling strategies on the ability to attain converged nonlinear deformations due to wrinkling. The numerical studies demonstrate that excessive mesh refinement in the regions of stress concentration may be disadvantageous to achieving wrinkled equilibrium states, causing the nonlinear solution to lock in the membrane response mode, while totally discarding the very low-energy bending response that is necessary to cause wrinkling deformation patterns.

  8. Oxidative stress responses of submerged macrophyte Vallisneria asiatica to different concentrations of cyanobacteria

    Science.gov (United States)

    Kang, Caixia; Kuba, Takahiro; Hao, Aimin; Iseri, Yasushi; Li, Chunjie; Zhang, Zhenjia

    2015-03-01

    In a 10-day aquarium experiment, this investigation examines macrophyte restoration in eutrophic Lake Taihu, the physiological effects of different plant biomass levels and of increasing natural cyanobacterial concentrations on a submerged macrophyte, Vallisneria asiatica. Cyanobacterial stress suppressed the superoxide dismutase (SOD) activity of the plant's leaves and induced the catalase (CAT) and peroxidase (POD) activities of its roots. The soluble protein content in V. asiatica decreased with an increase in natural cyanobacterial concentrations, whereas the malonaldehyde (MDA) increased significantly at chlorophyll a (Chl a) concentrations of 222 and 262 μg/L in water. V. asiatica adapted to the stress caused by cyanobacterial concentrations by adjusting its antioxidant defense system to remove the excessive reactive oxygen species when the algal Chl a concentration was >109 μg/L. Additionally, high biomass of V. asiatica (2 222 g FW/m2) can inhibit the reproduction of cyanobacteria more significantly than low biomass (1 111 g FW/m2). High biomass of V. asiatica increased the oxidative stress in an individual plant when the initial Chl a concentration in the water reached 222 and 262 μg/L, as expressed by the increased MDA in leaves, compared with low biomass of V. asiatica. This provides a basis for controlling cyanobacterial concentrations and V. asiatica biomass for the recovery of V. asiatica in eutrophic Lake Taihu.

  9. Effect of prenatal restraint stress and morphine co-administration on plasma vasopressin concentration and anxiety behaviors in adult rat offspring.

    Science.gov (United States)

    Nakhjiri, Elnaz; Saboory, Ehsan; Roshan-Milani, Shiva; Rasmi, Yousef; Khalafkhani, Davod

    2017-03-01

    Stressful events and exposure to opiates during gestation have important effects on the later mental health of the offspring. Anxiety is among the most common mental disorders. The present study aimed to identify effects of prenatal restraint stress and morphine co-administration on plasma vasopressin concentration (PVC) and anxiety behaviors in rats. Pregnant rats were divided into four groups (n = 6, each): saline, morphine, stress + saline and stress + morphine treatment. The stress procedure consisted of restraint twice per day, two hours per session, for three consecutive days starting on day 15 of pregnancy. Rats in the saline and morphine groups received either 0.9% saline or morphine intraperitoneally on the same days. In the morphine/saline + stress groups, rats were exposed to restraint stress and received either morphine or saline intraperitoneally. All offspring were tested in an elevated plus maze (EPM) on postnatal day 90 (n = 6, each sex), and anxiety behaviors of each rat were recorded. Finally, blood samples were collected to determine PVC. Prenatal morphine exposure reduced anxiety-like behaviors. Co-administration of prenatal stress and morphine increased locomotor activity (LA) and PVC. PVC was significantly lower in female offspring of the morphine and morphine + stress groups compared with males in the same group, but the opposite was seen in the saline + stress group. These data emphasize the impact of prenatal stress and morphine on fetal neuroendocrine development, with long-term changes in anxiety-like behaviors and vasopressin secretion. These changes are sex specific, indicating differential impact of prenatal stress and morphine on fetal neuroendocrine system development. Lay Summary Pregnant women are sometimes exposed to stressful and painful conditions which may lead to poor outcomes for offspring. Opiates may provide pain and stress relief to these mothers. In this study, we used an experimental model of

  10. Modified Weibull theory and stress-concentration factors of polycrystalline graphite

    International Nuclear Information System (INIS)

    Ho, F.H.

    1980-12-01

    Stress concentration factors (SCF) due to geometric discontinuities in graphite specimens are observed to be much less than the theoretical SCF in an elastic material. In fact, the experimental SCF is always less than two and sometimes even less than one. A four parameter Weibull theory which recognizes the grain size effect is found to give an adequate explanation of the above observed discrepancies

  11. The effect of acute physical and mental stress on soluble cellular adhesion molecule concentration.

    Science.gov (United States)

    Crabb, E Blake; Franco, R Lee; Caslin, Heather L; Blanks, Anson M; Bowen, Mary K; Acevedo, Edmund O

    2016-07-15

    This study investigated the impact of acute physical and mental stress on serum concentrations of vascular cell adhesion molecule (VCAM)-1 and CX3CL1/fractalkine. Male volunteers (n=20; 21.3±0.55years of age) completed a graded treadmill test to exhaustion and a 20-minute mental stress task (Stroop Color-Word Test, mental arithmetic) on separate, non-consecutive days. Heart rate (HR) was measured at baseline and throughout exercise and mental stress. Blood was collected at baseline (PRE), immediately following (POST) and 30min after (POST30) exercise and mental stress. Soluble VCAM-1 and fractalkine were quantified in participant serum via enzyme-linked immunosorbent assays. Both treadmill exercise and the mental stress task significantly increased participant HR; although, exercise resulted in a substantially greater increase in participant HR compared to mental stress (197.82±11.99 vs. 38.67±3.10% [pstress task did not significantly alter serum VCAM-1 or fractalkine at any time point. In conclusion, maximal aerobic exercise results in a significant elevation of the soluble adhesion molecules VCAM-1 and fractalkine in the serum of adult males that does not occur following laboratory-induced mental stress. The findings of the current investigation may suggest a novel protective role for acute aerobic exercise in vascular health via exercise-induced CAM proteolysis. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Elevated CSF Corticotropin-Releasing Factor Concentrations in Posttraumatic Stress Disorder

    Science.gov (United States)

    Bremner, J. Douglas; Licinio, Julio; Darnell, Adam; Krystal, John H.; Owens, Michael J.; Southwick, Steven M.; Nemeroff, Charles B.; Charney, Dennis S.

    2011-01-01

    Objective Corticotropin-releasing factor (CRF) and somatostatin both play important roles in mediating responses to acute and chronic stress. The purpose of this study was to measure CSF concentrations of CRF and somatostatin in patients with chronic combat-related post-traumatic stress disorder (PTSD) and comparison subjects. Method Lumbar punctures for collection of CSF were performed in Vietnam combat veterans with PTSD (N=11) and comparison subjects (N=17). CSF concentrations of CRF and somatostatin were compared between the two groups. Results CSF concentrations of CRF were higher in the PTSD patients than in the comparison subjects (mean=29.0 pg/ml, SD=7.8, versus mean=21.9 pg/ml, SD=6.0). This group difference remained significant after covariance for age. CSF somatostatin concentrations in PTSD patients were higher than those of the comparison subjects (mean=19.9 pg/ml, SD=5.4, versus mean=13.7 pg/ml, SD=8.0). However, covarying for age reduced the level of significance. Conclusions Higher CSF CRF concentrations in patients with PTSD may reflect alterations in stress-related neurotransmitter systems. The higher CSF CRF concentrations may play a role in disturbances of arousal in patients with PTSD. PMID:9137116

  13. Effect of Crack Tip Stress Concentration Factor on Fracture Resistance in Vacuum Environment

    Science.gov (United States)

    2015-01-20

    indicate: (1) in all alloys, the fracture resistance is highest for blunt-notches (smaller Kt), and is lowest for fatigue -sharpened precracked...paths are transgranular and the fracture mode is ductile void coalescence in all cases, irrespective of the stress concentration factor. 20-01-2015...because of corrosion and/or various loading conditions such as fatigue , fretting, abrasion, etc. Also, the geometry of the structure may cause an

  14. Surplus dietary tryptophan reduces plasma cortisol and noradrenaline concentrations and enhances recovery after social stress in pigs.

    Science.gov (United States)

    Koopmans, Sietse Jan; Ruis, Marko; Dekker, Ruud; van Diepen, Hans; Korte, Mechiel; Mroz, Zdzislaw

    2005-07-21

    Social stress occurs in intensive pig farming due to aggressive behavior. This stress may be reduced at elevated dietary levels of tryptophan (TRP). In this study, we compared the effects of high (13.2%) vs. normal (3.4%) dietary TRP to large neutral amino acid (LNAA) ratios on behavior and stress hormones in catheterized pigs ( approximately 50 kg BW), which were exposed to social stress by placing them twice into the territory of a dominant pig ( approximately 60 kg) for 15 min. Pre-stress plasma TRP concentrations were 156+/-15 vs. 53+/-6 micromol/l (psocial confrontations, pigs on the high vs. normal TRP diets show a tendency towards reduced active avoidance behavior (3.2+/-1.1 vs. 6.7+/-1.2 min, psocial confrontations, the post-stress plasma cortisol, noradrenaline and adrenaline concentrations and/or curves (from +5 min to 2 h) were lower/steeper (psurplus TRP in diets for pigs (1) does not significantly affect behavior when exposed to social stress, (2) reduces basal plasma cortisol and noradrenaline concentrations, (3) does not affect the immediate hormonal response to stress, and (4) reduces the long-term hormonal response to stress. In general, pigs receiving high dietary TRP were found to be less affected by stress.

  15. On the Stress Transfer of Nanoscale Interlayer with Surface Effects

    Directory of Open Access Journals (Sweden)

    Quan Yuan

    2018-01-01

    Full Text Available An improved shear-lag model is proposed to investigate the mechanism through which the surface effect influences the stress transfer of multilayered structures. The surface effect of the interlayer is characterized in terms of interfacial stress and surface elasticity by using Gurtin–Murdoch elasticity theory. Our calculation result shows that the surface effect influences the efficiency of stress transfer. The surface effect is enhanced with decreasing interlayer thickness and elastic modulus. Nonuniform and large residual surface stress distribution amplifies the influence of the surface effect on stress concentration.

  16. Numerical simulation of the double pits stress concentration in a curved casing inner surface

    Directory of Open Access Journals (Sweden)

    Wei Yan

    2016-12-01

    Full Text Available Sour or sweet oil fields development is common in recent years. Casing and tubing are usually subjected to pitting corrosion because of exposure to the strong corrosion species, such as CO2, H2S, and saline water. When the corrosion pits formed in the casing inner surface, localized stress concentration will occur and the casing strength will be degraded. Thus, it is essential to evaluate the degree of stress concentration factor accurately. This article performed a numerical simulation on double pits stress concentration factor in a curved inner surface using the finite element software ABAQUS. The results show that the stress concentration factor of double pits mainly depends on the ratio of two pits distance to the pit radius (L/R. It should not be only assessed by the absolute distance between the two pits. When the two pits are close and tangent, the maximum stress concentration factor will appear on the inner tangential edges. Stress concentration increased by double pits in a curved casing inner surface is more serious than that in a flat surface. A correction factor of 1.9 was recommended in the curved inner surface double pits stress concentration factor predict model.

  17. In vitro potential cytogenetic and oxidative stress effects of roxithromycin.

    Science.gov (United States)

    Arslan, Mehmet; Timocin, Taygun; Ila, Hasan B

    2017-10-01

    Macrolide antibiotic roxithromycin was evaluated in terms of its genotoxic, cytotoxic and oxidative stress effects. For this purpose; 25, 50, 100 and 200 μg/mL concentrations of roxithromycin were dissolved in dimethyl sulfoxide and treated to human peripheral blood lymphocytes for two different treatment periods (24 and 48 h). In chromosome aberration (CA) and micronucleus (MN) tests, roxithromycin did not show genotoxic effect. But it induced sister chromatid exchange (SCE) at the highest concentration (200 μg/mL) for the 24-h treatment period and at all concentrations (except 25 μg/mL) for the 48-h treatment period. Looking at cytotoxic effect of roxithromycin, statistically insignificant decreases on mitotic index and proliferation index were observed. Roxithromycin decreased nuclear division index (NDI) at highest two concentrations (100 and 200 μg/mL) for the 24-h treatment period and at all concentrations (expect 25 μg/mL) for the 48-h treatment period. Total oxidant values, total antioxidant values and oxidative stress index did not change with roxithromycin treatment. Eventually, roxithromycin did not have genotoxic and oxidative stress effects in human-cultured lymphocytes.

  18. Effects of potential and concentration of bicarbonate solution on stress corrosion cracking of annealed carbon steel

    International Nuclear Information System (INIS)

    Haruna, Takumi; Zhu, Liehong; Murakami, Makoto; Shibata, Toshio

    2000-01-01

    Effects of potential and concentration of bicarbonate on stress corrosion cracking (SCC) of annealed SM 400 B carbon steel has been investigated in bicarbonate solutions at 343 K. The surface of annealed specimen had decarburized layer of about 0. 5 mm thickness. A potentiostatic slow strain rate testing apparatus equipped with a charge coupled device camera system was employed to evaluate SCC susceptibility from the viewpoint of the crack behavior. In a constant bicarbonate concentration of 1 M, cracks were observed in the potential range from -800 to 600 mV Ag/ A gCl . and especially, the initiation and the propagation of the cracks were accelerated at -600 mV. At a constant potential of -600 mV, cracks were observed in the concentration range from 0.001 to 1 M, and the initiation and the propagation of the cracks were suppressed as the concentration decreased. Polarization curves for the decarburized surface were measured with two different scan rates. High SCC susceptibility may be expected in the potential range where the difference between the two current densities is large. It was found in this system that the potential with the maximum difference in the current density was -600 mV for 1 M bicarbonate solution, and the potential increased with a decrease in the concentration of bicarbonate. This means that an applied potential of -600 mV provides the highest SCC susceptibility for 1 M bicarbonate solution, and that the SCC susceptibility decreases as the concentration decreases. These findings support the dependence of the actual SCC behavior on the potential and the concentration of bicarbonate. (author)

  19. Micro-buckling of periodically layered composites in regions of stress concentration

    DEFF Research Database (Denmark)

    Poulios, Konstantinos; Niordson, Christian Frithiof

    2016-01-01

    -buckling related failure in regions of stress concentrations. A series of parametric studies show the effect of non-uniform stress distributions due to bending loads and the presence of geometrical features such as notches and holes on the initiation of micro-buckling. The contribution of the bending stiffness...... of the reinforcing layers on the resistance against micro-buckling introduces a dependence on the layer thickness, resulting in size-scale dependent strength limits. Therefore, both the shape and dimensions of the considered geometrical features and the layering thickness of the micro-structure are varied as part...... of the parametric studies. Moreover, the impact of imperfections in the composite micro-structure on the strength of the considered specimens is investigated....

  20. Effectiveness of stress release geometries on reducing residual stress in electroforming metal microstructure

    Science.gov (United States)

    Song, Chang; Du, Liqun; Zhao, Wenjun; Zhu, Heqing; Zhao, Wen; Wang, Weitai

    2018-04-01

    Micro electroforming, as a mature micromachining technology, is widely used to fabricate metal microdevices in micro electro mechanical systems (MEMS). However, large residual stress in the local positions of the micro electroforming layer often leads to non-uniform residual stress distributions, dimension accuracy defects and reliability issues during fabrication of the metal microdevice. To solve this problem, a novel design method of presetting stress release geometries in the topological structure of the metal microstructure is proposed in this paper. First, the effect of stress release geometries (circular shape, annular groove shape and rivet shape) on the residual stress in the metal microstructure was investigated by finite element modeling (FEM) analysis. Two evaluation parameters, stress concentration factor K T and stress non-uniformity factor δ were calculated. The simulation results show that presetting stress release geometries can effectively reduce and homogenize the residual stress in the metal microstructures were measured metal microstructure. By combined use with stress release geometries of annular groove shape and rivet shape, the stress concentration factor K T and the stress non-uniformity factor δ both decreased at a maximum of 49% and 53%, respectively. Meanwhile, the average residual stress σ avg decreased at a maximum of 20% from  -292.4 MPa to  -232.6 MPa. Then, micro electroforming experiments were carried out corresponding to the simulation models. The residual stresses in the metal microstructures were measured by micro Raman spectroscopy (MRS) method. The results of the experiment proved that the stress non-uniformity factor δ and the average residual stress σ avg also decreased at a maximum with the combination use of annular groove shape and rivet shape stress release geometries, which is in agreement with the results of FEM analysis. The stress non-uniformity factor δ has a maximum decrease of 49% and the

  1. Macro design effects on stress distribution around implants: a photoelastic stress analysis.

    Science.gov (United States)

    Ozkir, Serhat Emre; Terzioglu, Hakan

    2012-01-01

    Biomechanics is one of the main factors for achieving long-term success of implant supported prostheses. Long-term failures mostly depend on biomechanical complications. It is important to distinguish the effects of macro design of the implants. In this study, the photoelastic response of four different types of implants that were inserted with different angulations were comparatively analyzed. The implant types investigated were screw cylinder (ITI, Straumann AG, Basel, Switzerland), stepped cylinder (Frialit2, Friadent GmbH, Manheim, Germany), root form (Camlog Rootline, Alatatec, Wilshelm, Germany), and cylindrical implant, with micro-threads on the implant neck (Astra, AstraTech, Mölndal, Sweden). In the test models, one of the implants was inserted straight, while the other one was aligned mesially with 15° angles. The superstructures were prepared as single crowns. A 150N loading was applied to the restorations throughout the test. A comparison of the implant designs showed that there were no significant differences between the straight implants; however, between the inclined implants, the most favorable stress distribution was seen with the stepped cylinder implants. The least favorable stress concentration was observed around the root formed implants. Microthreads around the implant neck appeared to be effective in a homogenous stress distribution. Observations showed that misaligned implants caused less stress than straight implants, but the stress concentrations were not homogenous. As there were observable differences between the implant types, straight placed cylindrical implants showed better stress distribution characteristics, while inclined tapering implants had better stress distribution characteristics.

  2. Investigation of Stress Concentration and Casing Strength Degradation Caused by Corrosion Pits

    Directory of Open Access Journals (Sweden)

    Wei Yan

    2016-01-01

    Full Text Available Downhole casing and tubing are subjected to corrosion in many cases because of the exposure to corrosive environment. A more serious problem is that pitting corrosion occurs in the casing inner surface. Meanwhile, downhole strings are subjected to various forms of mechanical loads, for example, internal pressure load, external collapse load, or both. These loads acting on the corrosion pits will cause stress concentration and degrade the casing strength. Thus, it is essential to evaluate the stress concentration degree reasonably. The SCF (stress concentration factor is usually used to characterize the degree of stress concentration induced by corrosion pits. This paper presented a comparison on the SCFs regarding the analytical method for a single pit and experimental method for double pits. The results show that the SCF of a single pit depends mainly on the depth of the corrosion pit; however, the SCF of the double pits strongly depends on the pits distance. A correction factor of 1.3 was recommended in the double pits SCF prediction model.

  3. Effect of applied stress on the compressive residual stress introduced by laser peening

    International Nuclear Information System (INIS)

    Sumiya, Rie; Tazawa, Toshiyuki; Narazaki, Chihiro; Saito, Toshiyuki; Kishimoto, Kikuo

    2016-01-01

    Peening is the process which is able to be generated compressive residual stress and is known to be effective for preventing SCC initiation and improvement of fatigue strength. Laser peening is used for the nuclear power plant components in order to prevent SCC initiation. Although it is reported that the compressive residual stress decreases due to applied stresses under general operating condition, the change of residual stress might be large under excessive loading such as an earthquake. The objectives of this study are to evaluate the relaxation behavior of the compressive residual stress due to laser peening and to confirm the surface residual stress after loading. Therefore laser peened round bar test specimens of SUS316L which is used for the reactor internals of nuclear power plant were loaded at room temperature and elevated temperature and then surface residual stresses were measured by X-ray diffraction method. In the results of this test, it was confirmed that the compressive residual stress remained after applying uniform stress larger than 0.2% proof stress, and the effect of cyclic loading on the residual stress was small. The effect of applying compressive stress on the residual stress relaxation was confirmed to be less than that of applying tensile stress. Plastic deformation through a whole cross section causes the change in the residual stress distribution. As a result, the surface compressive residual stress is released. It was shown that the effect of specimen size on residual stress relaxation and the residual stress relaxation behavior in the stress concentration region can be explained by assumed stress relaxation mechanism. (author)

  4. Stress reaction in crayfish: chlorides help to withstand stress in high nitrite concentration conditions – preliminary study

    Directory of Open Access Journals (Sweden)

    Kozák P.

    2011-06-01

    Full Text Available A non-invasive method of recording cardiac activity (heart rate – HR and stress reaction (stress index – SI was used to understand the immediate and ongoing stress reaction of crayfish to the chemical stimuli. This method detects changes in the shape and amplitude parameters of the response to the stress factors, which characterized the crayfish functional state. Experimental animals (Astacus leptodactylus were divided to the two groups with (400 mg·L-1 Cl− and without added chlorides and then exposed to a stepwise increased level of nitrite to the final (sublethal-lethal concentration of 60 mg·L-1 N-NO\\hbox{$_{2}^{-}$}−2 within 24 hours. The course of crayfish reaction was evident and provided information about their reaction to the sublethal-lethal concentration over time. As expected, a less prominent stress reaction was detected in the group with chlorides. The non-invasive method successfully evaluated the sensing of chemical stimuli in water through HR and SI changes.

  5. Modelling and simulation of temperature and concentration dispersion in a couple stress nanofluid flow through stenotic tapered arteries

    Science.gov (United States)

    Ramana Reddy, J. V.; Srikanth, D.; Das, Samir K.

    2017-08-01

    A couple stress fluid model with the suspension of silver nanoparticles is proposed in order to investigate theoretically the natural convection of temperature and concentration. In particular, the flow is considered in an artery with an obstruction wherein the rheology of blood is taken as a couple stress fluid. The effects of the permeability of the stenosis and the treatment procedure involving a catheter are also considered in the model. The obtained non-linear momentum, temperature and concentration equations are solved using the homotopy perturbation method. Nanoparticles and the two viscosities of the couple stress fluid seem to play a significant role in the flow regime. The pressure drop, flow rate, resistance to the fluid flow and shear stress are computed and their effects are analyzed with respect to various fluids and geometric parameters. Convergence of the temperature and its dependency on the degree of deformation is effectively depicted. It is observed that the Nusselt number increases as the volume fraction increases. Hence magnification of molecular thermal dispersion can be achieved by increasing the nanoparticle concentration. It is also observed that concentration dispersion is greater for severe stenosis and it is maximum at the first extrema. The secondary flow of the axial velocity in the stenotic region is observed and is asymmetric in the tapered artery. The obtained results can be utilized in understanding the increase in heat transfer and enhancement of mass dispersion, which could be used for drug delivery in the treatment of stenotic conditions.

  6. Two-dimensional concentrated-stress low-frequency piezoelectric vibration energy harvesters

    Energy Technology Data Exchange (ETDEWEB)

    Sharpes, Nathan [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States); Abdelkefi, Abdessattar [Department of Mechanical and Aerospace Engineering, New Mexico State University, Las Cruces, New Mexico 88003 (United States); Priya, Shashank [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States); Bio-Inspired Materials and Devices Laboratory (BMDL), Virginia Tech, Blacksburg, Virginia 24061 (United States)

    2015-08-31

    Vibration-based energy harvesters using piezoelectric materials have long made use of the cantilever beam structure. Surmounting the deficiencies in one-dimensional cantilever-based energy harvesters has been a major focus in the literature. In this work, we demonstrate a strategy of using two-dimensional beam shapes to harvest energy from low frequency excitations. A characteristic Zigzag-shaped beam is created to compare against the two proposed two-dimensional beam shapes, all of which occupy a 25.4 × 25.4 mm{sup 2} area. In addition to maintaining the low-resonance bending frequency, the proposed beam shapes are designed with the goal of realizing a concentrated stress structure, whereby stress in the beam is concentrated in a single area where a piezoelectric layer may be placed, rather than being distributed throughout the beam. It is shown analytically, numerically, and experimentally that one of the proposed harvesters is able to provide significant increase in power production, when the base acceleration is set equal to 0.1 g, with only a minimal change in the resonant frequency compared to the current state-of-the-art Zigzag shape. This is accomplished by eliminating torsional effects, producing a more pure bending motion that is necessary for high electromechanical coupling. In addition, the proposed harvesters have a large effective beam tip whereby large tip mass may be placed while retaining a low-profile, resulting in a low volume harvester and subsequently large power density.

  7. Glutamate/glutamine concentrations in the dorsal anterior cingulate vary with Post-Traumatic Stress Disorder symptoms.

    Science.gov (United States)

    Harnett, Nathaniel G; Wood, Kimberly H; Ference, Edward W; Reid, Meredith A; Lahti, Adrienne C; Knight, Amy J; Knight, David C

    2017-08-01

    Trauma and stress-related disorders (e.g., Acute Stress Disorder; ASD and Post-Traumatic Stress Disorder; PTSD) that develop following a traumatic event are characterized by cognitive-affective dysfunction. The cognitive and affective functions disrupted by stress disorder are mediated, in part, by glutamatergic neural systems. However, it remains unclear whether neural glutamate concentrations, measured acutely following trauma, vary with ASD symptoms and/or future PTSD symptom expression. Therefore, the current study utilized proton magnetic resonance spectroscopy ( 1 H-MRS) to investigate glutamate/glutamine (Glx) concentrations within the dorsal anterior cingulate cortex (ACC) of recently (i.e., within one month) traumatized individuals and non-traumatized controls. Although Glx concentrations within dorsal ACC did not differ between recently traumatized and non-traumatized control groups, a positive linear relationship was observed between Glx concentrations and current stress disorder symptoms in traumatized individuals. Further, Glx concentrations showed a positive linear relationship with future stress disorder symptoms (i.e., assessed 3 months post-trauma). The present results suggest glutamate concentrations may play a role in both acute and future post-traumatic stress symptoms following a traumatic experience. The current results expand our understanding of the neurobiology of stress disorder and suggest glutamate within the dorsal ACC plays an important role in cognitive-affective dysfunction following a traumatic experience. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. High concentrations of Na+ and Cl- ions in soil solution have simultaneous detrimental effects on growth of faba bean under salinity stress.

    Science.gov (United States)

    Tavakkoli, Ehsan; Rengasamy, Pichu; McDonald, Glenn K

    2010-10-01

    Despite the fact that most plants accumulate both sodium (Na(+)) and chloride (Cl(-)) ions to high concentration in their shoot tissues when grown in saline soils, most research on salt tolerance in annual plants has focused on the toxic effects of Na(+) accumulation. There have also been some recent concerns about the ability of hydroponic systems to predict the responses of plants to salinity in soil. To address these two issues, an experiment was conducted to compare the responses to Na(+) and to Cl(-) separately in comparison with the response to NaCl in a soil-based system using two varieties of faba bean (Vicia faba), that differed in salinity tolerance. The variety Nura is a salt-sensitive variety that accumulates Na(+) and Cl(-) to high concentrations while the line 1487/7 is salt tolerant which accumulates lower concentrations of Na(+) and Cl(-). Soils were prepared which were treated with Na(+) or Cl(-) by using a combination of different Na(+) salts and Cl(-) salts, respectively, or with NaCl. While this method produced Na(+)-dominant and Cl(-)-dominant soils, it unavoidably led to changes in the availability of other anions and cations, but tissue analysis of the plants did not indicate any nutritional deficiencies or toxicities other than those targeted by the salt treatments. The growth, water use, ionic composition, photosynthesis, and chlorophyll fluorescence were measured. Both high Na(+) and high Cl(-) reduced growth of faba bean but plants were more sensitive to Cl(-) than to Na(+). The reductions in growth and photosynthesis were greater under NaCl stress and the effect was mainly additive. An important difference to previous hydroponic studies was that increasing the concentrations of NaCl in the soil increased the concentration of Cl(-) more than the concentration of Na(+). The data showed that salinity caused by high concentrations of NaCl can reduce growth by the accumulation of high concentrations of both Na(+) and Cl(-) simultaneously, but

  9. THE CONTAMINANT-ASSOCIATED STRESS RESPONSE AND ITS RELATIONSHIP TO PLASMA STRESS AND SEX STERIOD CONCENTRATIONS IN THE FLORIDA GAR, LEPISOSTEUS PLATYRHINCUS

    Science.gov (United States)

    Contaminants can alter the stress response. This study examined the stress response, defined by plasma cortisol concentration, and its relationship to plasma estradiol-17b and testosterone concentrations in adult gar collected from Lake Apopka, Orange Lake and Lake Woodruff NWR, ...

  10. The effect of couple-stresses on the stress concentration around a moving crack

    Directory of Open Access Journals (Sweden)

    S. Itou

    1981-01-01

    Full Text Available The problem of a uniformly propagating finite crack in an infinite medium is solved within the linearized couple-stress theory. The self-equilibrated system of pressure is applied to the crack surfaces. The problem is reduced to dual integral equations and solved by a series-expansion method. The dynamic stress-intensity factor is computed numerically.

  11. Rennet-induced gelation of concentrated milk in the presence of sodium caseinate: differences between milk concentration using ultrafiltration and osmotic stressing.

    Science.gov (United States)

    Krishnankutty Nair, P; Corredig, M

    2015-01-01

    Concentrating milk is a common unit operation in the dairy industry. With the reduction of water, the particles interact more frequently with each other and the functionality of the casein micelles may depend on the interactions occurring during concentration. The objective of this research was to investigate the effect of concentration on the renneting properties of the casein micelles by comparing 2 concentration methods: ultrafiltration and osmotic stressing. Both methods selectively concentrate the protein fraction of milk, while the composition of the soluble phase is unaltered. To evaluate possible differences in the rearrangements of the casein micelles during concentration, renneting properties were evaluated with or without the addition of soluble caseins, added either before or after concentration. The results indicate that casein micelles undergo rearrangements during concentration and that shear during membrane filtration may play a role in affecting the final properties of the milk. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  12. Social isolation stress and chronic glutathione deficiency have a common effect on the glutamine-to-glutamate ratio and myo-inositol concentration in the mouse frontal cortex.

    Science.gov (United States)

    Corcoba, Alberto; Gruetter, Rolf; Do, Kim Q; Duarte, João M N

    2017-09-01

    Environmental stress can interact with genetic predisposition to increase the risk of developing psychopathology. In this work, we tested the hypothesis that social isolation stress interacts with impaired glutathione synthesis and have cumulative effects on the neurochemical profile of the frontal cortex. A mouse model with chronic glutathione deficit induced by knockout (-/-) of the glutamate-cysteine ligase modulatory subunit (Gclm) was exposed to social isolation stress from weaning to post-natal day 65. Using magnetic resonance methods at high-field (14.1 T), we analysed the neurochemical profile in the frontal cortex, brain size and ventricular volume of adult animals. Glutathione deficit was accompanied by elevated concentrations of N-acetylaspartate, alanine, and glutamine, as well as the ratio of glutamine-to-glutamate (Gln/Glu), and by a reduction in levels of myo-inositol and choline-containing compounds in the frontal cortex of -/- animals with respect to wild-type littermates. Although there was no significant interaction between social isolation stress and glutathione deficiency, mice reared in isolation displayed lower myo-inositol concentration (-8.4%, p social isolation had no effect on these parameters. We conclude that social isolation caused neurochemical alterations that may add to those associated to impaired glutathione synthesis. © 2017 International Society for Neurochemistry.

  13. Stress Concentration and Its Mitigation Techniques in Flat Plate with Singularities - A Critical Review

    Directory of Open Access Journals (Sweden)

    Shubhashish Sanyal

    2012-01-01

    Full Text Available A number of analytical, numerical & experimental techniques are available for the reduction of stress concentration factor around discontinuities. Using various techniques the SCF around different discontinuities in a rectangular plate made up of different materials under different loading conditions have been reported in literature. Mitigation of stress concentration around different types of discontinuity is also reported in literature. This paper is to present an analysis and overview of emerging techniques developed for analysis as well as mitigation of stress concentration. The proposed methods in literature are compared.

  14. Correlation of Stress Concentration Factors for T-Welded Connections – Finite Element Simulations and Fatigue Behavior

    Directory of Open Access Journals (Sweden)

    Gerardo Terán Méndez

    Full Text Available Abstract The stress concentration factors (SCFs in welded connections usually occur at zones with high stress levels. Stress concentrations reduce the fatigue behavior of welded connections in offshore structures and cracking can develop. By using the grinding technique, cracking can be eliminated. Stress concentration factors are defined as a ratio of maximum stress at the intersection to nominal stress on the brace. Defining the stress concentration factor is an important stage in the fatigue behavior of welded connections. Several approaches have evolved for designing structures with the classical S-N approach for estimating total life. This work correlates to the stress concentration factors of T-welded connections and the fatigue behavior. Stress concentration factors were computed with the finite element employing 3D T-welded connections with intact and grinding depth conditions. Then, T-welded connections were constructed with A36 plate steel and welded with E6013 electrodes to obtain the stress-life (S-N approach. The methodology from previous works was used to compute the SCF and fabricate the T-welded connections. The results indicated that the grinding process could restore the fatigue life of the T-welded connections for SCFs values in the range of 1.29. This value can be considered to be a low SCF value in T-welded connection. However, for higher SCF values, the fatigue life decreased, compromising and reducing the structural integrity of the T-welded connections.

  15. Stress concentrations in an impregnated fibre bundle with random fibre packing

    OpenAIRE

    Swolfs, Y.; Gorbatikh, L.; Romanov, V.; Orlova, S.; Lomov, S. V.; Verpoest, I.

    2013-01-01

    The stress redistribution after a single fibre break is a fundamental issue in longitudinal strength models for unidirectional composites. Current models assume hexagonal or square fibre packings. In the present work, random fibre packings were modelled using 3D finite element analysis and compared to ordered fibre packings. Significant differences in the stress redistribution are found. Compared to square and hexagonal packings, random fibre packings result in smaller stress concentration fa...

  16. Effects of dietary selenium on tissue concentrations,pathology, oxidative stress, and immune function in common eiders (Somateria mollissima)

    Science.gov (United States)

    Franson, J. Christian; Hoffman, David; Wells-Berlin, Alicia M.; Perry, Matthew C.; Shearn-Bochsler, Valerie I.; Finley, Daniel L.; Flint, Paul L.; Hollmén, Tuula E.

    2007-01-01

    Common eiders (Somateria mollissima) were fed added Se (as L-selenomethionine) in concentrations increasing from 10 to 80 ppm in a pilot study (Study 1) or 20 (low exposure) and up to 60 (high exposure) ppm Se in Study 2. Body weights of Study 1 ducks and high-exposure ducks in Study 2 declined rapidly. Mean concentrations of Se in blood reached 32.4 ppm wet weight in Study 1 and 17.5 ppm wet weight in high-exposure birds in Study 2. Mean Se concentrations in liver ranged from 351 (low exposure, Study 2) to 1252 ppm dry weight (Study 1). Oxidative stress was evidenced by Se-associated effects on glutathione metabolism. As Se concentrations in liver increased, Se-dependent glutathione peroxidase activity, glutathione reductase activity, oxidized glutathione levels, and the ratio of hepatic oxidized to reduced glutathione increased. In Study 2, the T-cell-mediated immune response was adversely affected in high-exposure eiders, but ducks in the low-exposure group exhibited evidence of an enhanced antibody-mediated immune response. Gross lesions in high-exposure ducks included emaciation, absence of thymus, and loss of nails from digits. Histologic lesions included severe depletion of lymphoid organs, hepatopathy, and necrosis of feather pulp and feather epithelium. Field studies showed that apparently healthy sea ducks generally have higher levels of Se in liver than healthy fresh-water birds, but lower than concentrations found in our study. Data indicate that common eiders and probably other sea ducks possess a higher threshold, or adverse effect level, for Se in tissues than fresh-water species. However, common eiders developed signs of Se toxicity similar to those seen in fresh-water birds.

  17. Dietary supplementation with a superoxide dismutase-melon concentrate reduces stress, physical and mental fatigue in healthy people: a randomised, double-blind, placebo-controlled trial.

    Science.gov (United States)

    Carillon, Julie; Notin, Claire; Schmitt, Karine; Simoneau, Guy; Lacan, Dominique

    2014-06-19

    We aimed to investigate effects of superoxide dismutase (SOD)-melon concentrate supplementation on psychological stress, physical and mental fatigue in healthy people. A randomized, double-blind, placebo-controlled trial was performed on 61 people divided in two groups: active supplement (n = 32) and placebo (n = 29) for 12 weeks. Volunteers were given one small hard capsule per day. One capsule contained 10 mg of SOD-melon concentrate (140 U of SOD) and starch for the active supplement and starch only for the placebo. Stress and fatigue were evaluated using four psychometric scales: PSS-14; SF-36; Stroop tests and Prevost scale. The supplementation with SOD-melon concentrate significantly decreased perceived stress, compared to placebo. Moreover, quality of life was improved and physical and mental fatigue were reduced with SOD-melon concentrate supplementation. SOD-melon concentrate supplementation appears to be an effective and natural way to reduce stress and fatigue. trial approved by the ethical committee of Poitiers (France), and the ClinicalTrials.gov Identifier is NCT01767922.

  18. Effects of Salinity Stress on Gas Exchange, Growth, and Nutrient Concentrations of Two Citrus Rootstocks

    Directory of Open Access Journals (Sweden)

    D. Khoshbakht

    2015-03-01

    Full Text Available A greenhouse study was undertaken to assess the salt tolerance of two citrus rootstocks, namely, Bakraii (Citrus sp. and Trifoliate orange (Poncirus trifoliata. A factorial experiment through a completely randomized design (CRD with three replications and four levels of salt including 0, 20, 40 and 60 mM NaCl was conducted. After eight weeks of treatment, number of leaves, plant height, leaf area, wet and dry weight of leaf, stem and root, length of root, chlorophyll content, net CO2 assimilation rate (ACO2, stomatal conductance (gs, transpiration (E and water use efficiency (WUE and ion concentrations were measured. Salinity decreased growth and net gas exchange. Trifoliate orange showed the most decrease in growth indices and net gas exchange compared with Bakraii. The ability to limit the transfer of sodium to leaves in low levels of salt was observed in Trifoliate orange, but this ability was not observed in high levels of salt. Results showed that accumulation of chloride in leaves and roots were less in Bakraii compared to the Trifoliate orange. The lower Cl- concentration in leaves of Bakraii than trifoliate orange suggests that the salinity tolerance of Bakraii is associated with less transport of Cl- to the leaves. Salinity increased K+ and decreased Mg2+ and Ca2+ concentrations in leaves of both rootstocks. It is proposed that salt stress effect on plant physiological processes such as changes in plant growth, Cl- and Na+ toxicity, and mineral distribution, decreases chlorophyll content and reduces the photosynthetic efficiency of these citrus species.

  19. Nutrients versus emerging contaminants–Or a dynamic match between subsidy and stress effects on stream biofilms

    International Nuclear Information System (INIS)

    Aristi, I.; Casellas, M.; Elosegi, A.; Insa, S.; Petrovic, M.; Sabater, S.; Acuña, V.

    2016-01-01

    Freshwater ecosystems are threatened by multiple anthropogenic stressors, which might be differentiated into two types: those that reduce biological activity at all concentrations (toxic contaminants), and those that subsidize biological activity at low concentrations and reduce it at high concentrations (assimilable contaminants). When occurring in mixtures, these contaminants can have either antagonistic, neutral or synergistic effects; but little is known on their joint effects. We assessed the interaction effects of a mixture of assimilable and toxic contaminants on stream biofilms in a manipulative experiment using artificial streams, and following a factorial design with three nutrient levels (low, medium or high) and either presence or absence of a mixture of emerging contaminants (ciprofloxacin, erythromycin, diclofenac, methylparaben, and sulfamethoxazole). We measured biofilm biomass, basal fluorescence, gross primary production and community respiration. Our initial hypotheses were that biofilm biomass and activity would: increase with medium nutrient concentrations (subsidy effect), but decrease with high nutrient concentrations (stress effect) (i); decrease with emerging contaminants, with the minimum decrease at medium nutrient concentrations (antagonistic interaction between nutrients subsidy and stress by emerging contaminants) and the maximum decrease at high nutrient concentrations (synergistic interaction between nutrients and emerging contaminants stress) (ii). All the measured variables responded linearly to the available nutrients, with no toxic effect at high nutrient concentrations. Emerging contaminants only caused weak toxic effects in some of the measured variables, and only after 3–4 weeks of exposure. Therefore, only antagonistic interactions were observed between nutrients and emerging contaminants, as medium and high nutrient concentrations partly compensated the harmful effects of emerging contaminants during the first weeks of the

  20. Suggested benchmarks for shape optimization for minimum stress concentration

    DEFF Research Database (Denmark)

    Pedersen, Pauli

    2008-01-01

    Shape optimization for minimum stress concentration is vital, important, and difficult. New formulations and numerical procedures imply the need for good benchmarks. The available analytical shape solutions rely on assumptions that are seldom satisfied, so here, we suggest alternative benchmarks...

  1. [Effect of exogenous sucrose on growth and active ingredient content of licorice seedlings under salt stress conditions].

    Science.gov (United States)

    Liu, Fu-zhi; Yang, Jun

    2015-11-01

    Licorice seedlings were taken as experimental materials, an experiment was conducted to study the effects of exogenous sucrose on growth and active ingredient content of licorice seedlings under NaCl stress conditions. The results of this study showed that under salt stress conditions, after adding a certain concentration of exogenous sucrose, the licorice seedlings day of relative growth rate was increasing, and this stress can be a significant weakening effect, indicating that exogenous sucrose salt stress-relieving effect. The total flavonoids and phenylalanine ammonia lyase (PAL) activity were significantly increased, the exogenous sucrose can mitigated the seedling roots under salt stress, the licorice flavonoid content in the enhanced growth was largely due to the activity of PAL an increased, when the concentration of exogenous sucrose wae 10 mmol x L(-1), PAL activity reaching a maximum, when the concentration of exogenous sucrose was 15 mmol x L(-1), PAL activity turned into a downward trend, the results indicating that this mitigation has concentration effect. After applying different concentrations of exogenous sugar, the contents of liquiritin changes with the change of flavonoids content was similar. After applying different concentrations of exogenous sucrose, the content of licorice acid under salt stress was higher than the levels were not reached during salt stress, the impact of exogenous sucrose concentration gradient of licorice acid accumulation was not obvious.

  2. Abiotic stress growth conditions induce different responses in kernel iron concentration across genotypically distinct maize inbred varieties

    Science.gov (United States)

    Kandianis, Catherine B.; Michenfelder, Abigail S.; Simmons, Susan J.; Grusak, Michael A.; Stapleton, Ann E.

    2013-01-01

    The improvement of grain nutrient profiles for essential minerals and vitamins through breeding strategies is a target important for agricultural regions where nutrient poor crops like maize contribute a large proportion of the daily caloric intake. Kernel iron concentration in maize exhibits a broad range. However, the magnitude of genotype by environment (GxE) effects on this trait reduces the efficacy and predictability of selection programs, particularly when challenged with abiotic stress such as water and nitrogen limitations. Selection has also been limited by an inverse correlation between kernel iron concentration and the yield component of kernel size in target environments. Using 25 maize inbred lines for which extensive genome sequence data is publicly available, we evaluated the response of kernel iron density and kernel mass to water and nitrogen limitation in a managed field stress experiment using a factorial design. To further understand GxE interactions we used partition analysis to characterize response of kernel iron and weight to abiotic stressors among all genotypes, and observed two patterns: one characterized by higher kernel iron concentrations in control over stress conditions, and another with higher kernel iron concentration under drought and combined stress conditions. Breeding efforts for this nutritional trait could exploit these complementary responses through combinations of favorable allelic variation from these already well-characterized genetic stocks. PMID:24363659

  3. Effects of Cynodon dactylon on Stress-Induced Infertility in Male Rats

    Science.gov (United States)

    Chidrawar, VR; Chitme, HR; Patel, KN; Patel, NJ; Racharla, VR; Dhoraji, NC; Vadalia, KR

    2011-01-01

    Cynodon dactylon (Family: Poaceae) is known to be a tackler in Indian mythology and is offered to Lord Ganesha. It is found everywhere, even on waste land, road side, dry places, and spreads vigorously on cultivated ground. This study was carried out with an objective to test if the constituents of this plant are useful in coping stress-induced sexual In this study, we considered immobilization stress to induce male infertility and the effect of C. dactylon in restoration of the dysfunction was evaluated by considering sexual behavioral observations, sexual performance, fructose content of the seminal vesicles, epididymal sperm concentration and histopathological examinations as parameters. Treatment of rats under stress with methanolic extract of C. dactylon has shown a promising effect in overcoming stress-induced sexual dysfunction, sexual performance, fructose content, sperm concentration and its effect on accessory sexual organs and body weight. We conclude that active constituents of C. dactylon present in methanolic extract have a potent aphrodisiac and male fertility activity. PMID:21607051

  4. Impacts of simulated drought stress and artificial damage on concentrations of flavonoids in Jatropha curcas (L.), a biofuel shrub.

    Science.gov (United States)

    Lama, Ang Dawa; Kim, Jorma; Martiskainen, Olli; Klemola, Tero; Salminen, Juha-Pekka; Tyystjärvi, Esa; Niemelä, Pekka; Vuorisalo, Timo

    2016-11-01

    We studied the possible roles of flavonoids in the antioxidant and antiherbivore chemistry in Jatropha curcas (L.), a Latin American shrub that holds great potential as a source of biofuel. Changes in flavonoid concentrations in the leaves of J. curcas seedlings exposed to artificial damage and to different rainfall patterns were assessed by applying a 3 2 -factorial experiment in a greenhouse. The concentrations of different flavonoids in the leaves of seedlings were significantly affected by interaction effects of artificial damage, drought stress and age of the seedling. The highest flavonoid concentrations were obtained in seedlings imposed to the highest percentage of artificial damage (50 %) and grown under extreme drought stress (200 mm year -1 ). In this treatment combination, flavonoid concentrations were three-fold as compared to seedlings exposed to the same level of artificial damage but grown in 1900 mm year -1 rainfall application. Without artificial damage, the concentration of flavonoids in the seedlings grown in 200 mm year -1 rainfall application was still two-fold compared to seedlings grown in higher (>800 mm year -1 ) rainfall applications. Thus, the observed flavonoid concentration patterns in the leaves of J. curcas seedlings were primarily triggered by drought stress and light rather than by artificial damage, suggesting that drought causes oxidative stress in J. curcas.

  5. Dietary Supplementation with a Superoxide Dismutase-Melon Concentrate Reduces Stress, Physical and Mental Fatigue in Healthy People: A Randomised, Double-Blind, Placebo-Controlled Trial

    Directory of Open Access Journals (Sweden)

    Julie Carillon

    2014-06-01

    Full Text Available Background: We aimed to investigate effects of superoxide dismutase (SOD-melon concentrate supplementation on psychological stress, physical and mental fatigue in healthy people. Methods: A randomized, double-blind, placebo-controlled trial was performed on 61 people divided in two groups: active supplement (n = 32 and placebo (n = 29 for 12 weeks. Volunteers were given one small hard capsule per day. One capsule contained 10 mg of SOD-melon concentrate (140 U of SOD and starch for the active supplement and starch only for the placebo. Stress and fatigue were evaluated using four psychometric scales: PSS-14; SF-36; Stroop tests and Prevost scale. Results: The supplementation with SOD-melon concentrate significantly decreased perceived stress, compared to placebo. Moreover, quality of life was improved and physical and mental fatigue were reduced with SOD-melon concentrate supplementation. Conclusion: SOD-melon concentrate supplementation appears to be an effective and natural way to reduce stress and fatigue. Trial registration: trial approved by the ethical committee of Poitiers (France, and the ClinicalTrials.gov Identifier is NCT01767922.

  6. Thermal stress effects in intermetallic matrix composites

    Science.gov (United States)

    Wright, P. K.; Sensmeier, M. D.; Kupperman, D. S.; Wadley, H. N. G.

    1993-01-01

    Intermetallic matrix composites develop residual stresses from the large thermal expansion mismatch (delta-alpha) between the fibers and matrix. This work was undertaken to: establish improved techniques to measure these thermal stresses in IMC's; determine residual stresses in a variety of IMC systems by experiments and modeling; and, determine the effect of residual stresses on selected mechanical properties of an IMC. X ray diffraction (XRD), neutron diffraction (ND), synchrotron XRD (SXRD), and ultrasonics (US) techniques for measuring thermal stresses in IMC were examined and ND was selected as the most promising technique. ND was demonstrated on a variety of IMC systems encompassing Ti- and Ni-base matrices, SiC, W, and Al2O3 fibers, and different fiber fractions (Vf). Experimental results on these systems agreed with predictions of a concentric cylinder model. In SiC/Ti-base systems, little yielding was found and stresses were controlled primarily by delta-alpha and Vf. In Ni-base matrix systems, yield strength of the matrix and Vf controlled stress levels. The longitudinal residual stresses in SCS-6/Ti-24Al-llNb composite were modified by thermomechanical processing. Increasing residual stress decreased ultimate tensile strength in agreement with model predictions. Fiber pushout strength showed an unexpected inverse correlation with residual stress. In-plane shear yield strength showed no dependence on residual stress. Higher levels of residual tension led to higher fatigue crack growth rates, as suggested by matrix mean stress effects.

  7. Assessment of fructosamine concentrations in cats with acute and chronic stress

    Directory of Open Access Journals (Sweden)

    Lívia Fagundes Moraes

    2011-10-01

    Full Text Available Fructosamine are glycated serum proteins that are formed continuously due to the reaction between glucose and circulating proteins, and corresponding to the blood glucose control assessment over the last one to two weeks in cats. The fructosamine concentration has been used for differentiation between persistent and transient hyperglycemia. Therefore, the determination of fructosamine is considered the gold standard for monitoring glycemia into control in diabetic cats. The objective of this study was to evaluate the influence of acute and chronic stress of cats on serum fructosamine. 62 cats were selected from the Veterinary Hospital of FMVZ - UNESP, Botucatu campus. They were distributed into three groups: cats with a history of any illness or stress condition, excluding Diabetes Mellitus (DM, for a maximum of 48 hours (Group A, n = 21 or for a period exceeding 120 hours (Group B n = 27. The third group (Group C = control was formed by 14 health cats. The groups were evaluated for serum fructosamine, glucose, protein and albumin. In this study, there was a significant increase in the values of fructosamine in animals subjected to acute and chronic stress, but these values remained within the reference range. The animals were, on average, normoglycemic, despite the positive correlation between fructosamine and glucose concentrations. We conclude that the fructosamine concentration is influenced by acute and chronic stress in cats, remaining, however, within the reference range, and therefore, still useful in the diagnosis of DM.

  8. Immediate and residual effects of heat stress and restricted intake on milk protein and casein composition and energy metabolism.

    Science.gov (United States)

    Cowley, F C; Barber, D G; Houlihan, A V; Poppi, D P

    2015-04-01

    The effects of heat stress on dairy production can be separated into 2 distinct causes: those effects that are mediated by the reduced voluntary feed intake associated with heat stress, and the direct physiological and metabolic effects of heat stress. To distinguish between these, and identify their effect on milk protein and casein concentration, mid-lactation Holstein-Friesian cows (n = 24) were housed in temperature-controlled chambers and either subjected to heat stress [HS; temperature-humidity index (THI) ~78] or kept in a THIheat-stressed cows (TN-R) for 7 d. A control group of cows was kept in a THIheat stress. Heat stress reduced the milk protein concentration, casein number, and casein concentration and increased the urea concentration in milk beyond the effects of restriction of intake. Under HS, the proportion in total casein of αS1-casein increased and the proportion of αS2-casein decreased. Because no effect of HS on milk fat or lactose concentration was found, these effects appeared to be the result of specific downregulation of mammary protein synthesis, and not a general reduction in mammary activity. No residual effects were found of HS or TN-R on milk production or composition after THIHeat-stressed cows had elevated blood concentrations of urea and Ca, compared with TN-R and TN-AL. Cows in TN-R had higher serum nonesterified fatty acid concentrations than cows in HS. It was proposed that HS and TN-R cows may mobilize different tissues as endogenous sources of energy. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  9. Creep cavitation in the neighborhood of stress concentrations

    International Nuclear Information System (INIS)

    Liu, T.S.; Delph, T.J.; Fields, R.J.

    1983-01-01

    The results of several experiments into the formation and distribution of creep cavitation in the neighborhood of stress concentrations is reported. Of particular interest is the use of an image analyzing computer to construct quantitative maps of cavity sizes and distributions. Comparisons are drawn in one case with the results of a finite element simulation, and some degree of overall agreement is noted. (orig.)

  10. Effect of Plant Growth Promoting Rhizobacteria on the Concentration and Uptake of Macro Nutrients by Corn in a Cd-contaminated Calcareous Soil under Drought Stress

    Directory of Open Access Journals (Sweden)

    shahrzad karami

    2017-02-01

    Full Text Available Introduction: Heavy metals such as cadmium (Cd are found naturally in soils, but their amount can be changed by human activities. The study of the uptake and accumulation of heavy metals by plants is done in order to prevent their threats on human and animal’s health.Cadmium is a toxic element for living organisms. Cadmium competes with many of nutrients to be absorbed by the plant and interferes with their biological roles. Water stress affects the cell structure and the food is diverted from its normal metabolic pathway. It also reduces the availability and uptake of nutrients by the plant. One reason for the reduction of plant growth under drought stress is the accumulation of ethylene in plants. There are ways to mitigate the negative effects of drought stress that one of which is the use of Plant Growth Promoting Rhizobacteria(PGPRs to increasing the availability of nutrients. Soil beneficial bacteria play an important role in the biological cycles and have been used to increase plant health and soil fertility over the past few decades.The aim of this study was to investigate theeffect of PGPRson the concentration and uptake of macro nutrients by corn in a Cd-contaminated calcareous soil under drought stress. Materials and Methods: A greenhouse factorial experiment was conducted in a completely randomized design with three replications. The treatments were two levels of bacteria (with and without bacteria, four levels of Cd (5, 10, 20, and 40 mg kg-1, and three levels of drought stress (without stress, 80, and 65% of field capacity. The pots were filled with 3 kg of treated soil. Cd was treated as its sulfate salt in amounts of 5, 10, 20, and 40 mg kg-1. The soil was mixed uniformly with 150 mg N kg-1 as urea, 20 mg P kg-1 as Ca (H2PO42, 5 mg Fe kg-1 as Fe-EDDHA and 10, 10 and 2.5 mg Zn, Mn and Cu kg-1, respectively as their sulfate salt in order to meet plant needs for these nutrients. Six seeds of Zea mays (var. HIDO were planted at

  11. Nutrients versus emerging contaminants-Or a dynamic match between subsidy and stress effects on stream biofilms.

    Science.gov (United States)

    Aristi, I; Casellas, M; Elosegi, A; Insa, S; Petrovic, M; Sabater, S; Acuña, V

    2016-05-01

    Freshwater ecosystems are threatened by multiple anthropogenic stressors, which might be differentiated into two types: those that reduce biological activity at all concentrations (toxic contaminants), and those that subsidize biological activity at low concentrations and reduce it at high concentrations (assimilable contaminants). When occurring in mixtures, these contaminants can have either antagonistic, neutral or synergistic effects; but little is known on their joint effects. We assessed the interaction effects of a mixture of assimilable and toxic contaminants on stream biofilms in a manipulative experiment using artificial streams, and following a factorial design with three nutrient levels (low, medium or high) and either presence or absence of a mixture of emerging contaminants (ciprofloxacin, erythromycin, diclofenac, methylparaben, and sulfamethoxazole). We measured biofilm biomass, basal fluorescence, gross primary production and community respiration. Our initial hypotheses were that biofilm biomass and activity would: increase with medium nutrient concentrations (subsidy effect), but decrease with high nutrient concentrations (stress effect) (i); decrease with emerging contaminants, with the minimum decrease at medium nutrient concentrations (antagonistic interaction between nutrients subsidy and stress by emerging contaminants) and the maximum decrease at high nutrient concentrations (synergistic interaction between nutrients and emerging contaminants stress) (ii). All the measured variables responded linearly to the available nutrients, with no toxic effect at high nutrient concentrations. Emerging contaminants only caused weak toxic effects in some of the measured variables, and only after 3-4 weeks of exposure. Therefore, only antagonistic interactions were observed between nutrients and emerging contaminants, as medium and high nutrient concentrations partly compensated the harmful effects of emerging contaminants during the first weeks of the

  12. Early stress responses in Atlantic salmon (Salmo salar) exposed to environmentally relevant concentrations of uranium

    International Nuclear Information System (INIS)

    Song You; Salbu, Brit; Heier, Lene Sørlie; Teien, Hans-Christian; Lind, Ole-Christian; Oughton, Deborah; Petersen, Karina; Rosseland, Bjørn Olav; Skipperud, Lindis; Tollefsen, Knut Erik

    2012-01-01

    Uranium (U) is a naturally occurring heavy metal widely used in many military and civil applications. Uranium contamination and the associated potential adverse effects of U on the aquatic environment have been debated during recent years. In order to understand the effect and mode of action (MoA) of U in vivo, juvenile Atlantic salmon (Salmo salar) were exposed to 0.25 mg/L, 0.5 mg/L and 1.0 mg/L waterborne depleted uranyl acetate, respectively, in a static system for 48 h. The U concentrations in the gill and liver were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) and the resulting biological effects were determined by a combination of analysis of gene expression and micronuclei formation. The hepatic transcriptional level of 12 biomarker genes from four stress–response categories, including oxidative stress (γ-glutamyl cysteine synthetase (GCS), glutathione reductase (GR), glutathione peroxidase (GPx)), DNA damage and repair (P53, cyclin-dependent kinase inhibitor 1 (P21), growth arrest and DNA damage-inducible gene gamma (Gadd45G), proliferating cell nuclear antigen (PCNA), Rad51), apoptosis (Bcl2-associated X protein (BAX), Bcl-x, Caspase 6A,) and protein degradation (Ubiquitin) were evaluated by quantitative real-time polymerase chain reaction (q-rtPCR). The results clearly showed accumulation of U in the gill and liver with increasing concentrations of U in the exposure water. The effects of U on differential hepatic gene expression also occurred in a concentration-dependent manner, although deviations from ideal concentration–response relationships were observed at the highest U concentration (1.0 mg/L). All the genes tested were found to be up-regulated by U while no significant micronuclei formation was identified. The results suggest that U may cause oxidative stress in fish liver at concentrations greater than 0.25 mg/L, giving rise to clear induction of several toxicologically relevant biomarker genes, although no significant

  13. Three Dimensional Parametric Analyses on Effect of Fibre Orientation for Stress Concentration Factor in Fibrous Composite Cantilever Plate with Central Circular Hole under Transverse Loading

    Directory of Open Access Journals (Sweden)

    Nitin Jain

    2012-10-01

    Full Text Available Normal 0 false false false EN-IN X-NONE X-NONE ABSTRACT: A number of analytical and numerical techniques are available for the two dimensional study of stress concentration around the hole(s in isotropic and composite plates subjected to in-plane or transverse loading conditions. The information on the techniques for three dimensional analyses of stress concentration factor (SCF around the hole in isotropic and composite plates subjected to transverse loading conditions is, however, limited. The present work emphasizes on the effect of fibre orientation (q on the stress concentration factor in fibrous composite plates with central circular hole under transverse static loading condition. The work is carried out for cantilever fibrous composite plates. The effects of thickness -to- width (T/A and diameter-to-width (D/A ratios upon SCF at different fibre orientation are studied. Plates of four different composite materials were considered for hole analysis in order to determine the sensitivity of SCF with elastic constants. Deflections in transverse direction were calculated and analysed. All results are presented in graphical form and discussed. The finite element formulation and its analysis were carried out using ANSYS package.ABSTRAK: Terdapat pelbagai teknik analitikal dan numerical untuk kajian tumpuan tegasan dua dimensi di sekeliling lubang-lubang dalam komposit isotropik dan plat pada satah atau keadaan bebanan melintang. Bagaimanapun, maklumat mengenai kaedah analisis tiga dimensi untuk faktor ketumpatan tegasan (SCF sekitar lubang dalam komposit isotropik dan plat pada keadaan bebanan melintang adalah terhad. Kertas ini menekankan kesan orientasi gentian (q pada faktor tumpuan tegasan dalam komposit plat bergentian dengan lubang berpusat di bawah keadaan bebanan melintang. Kajian ini dilkukan untuk cantilever plat komposit bergentian. Kesan ketebalan terhadap kelebaran plat (T/A dan diameter terhadap kelebaran komposit (D/A dengan SCF

  14. Response of Yield, Yield Components and Nutrient Concentration of Cumin (Cuminum cyminum L. to Mycorrhizal Symbiosis under Salt Stress Conditions

    Directory of Open Access Journals (Sweden)

    M. Bijhani

    2016-01-01

    Full Text Available To study the effects of mycorrhizal inoculation and salinity stress on the growth, yield and nutrient concentrations of cumin (Cuminum cyminum L., an experiment was carried out as split plot in a completely randomized block design at Zabol University Research Farm in 2013. Treatments consisted of three salinity stresses: 1 (control, 5 and 10 dSm-1, was considered as the main treatments, and four levels of mycorrhizal inoculation (Glomus intraradices, G. etanicatum, G. hoi and non-inoculation as control as the sub-treatments. The effects of salinity on all traits under study, except umbers per plant, were significant, and severe stress (10 dSm-1 reduced 100 seed weight, number of seeds per umbel, concentrations of phosphorus, calcium and magnesium in seeds by 17.71, 11.4, 14.95, 46.08, 13.60 %, respectively, as compared to the control. The numbers of seeds per umbel and phosphorus concentration in seed were highest in G. intraradices with 28.4 and 54.4%, respectively as compared to control and umbels per plant was also maximum (9.7 by using G. etanicatum. Mycorrhizal inoculation did not have significant effect on calcium and magnesium concentrations in seeds and 1000 seed weight. However mycorrhiza × salinity stress interaction was significant about concentration of sodium, potassium and sodium to potassium ratio (Na/K in seeds, as well as seed yield and seed number per plant. Among the species of mycorrhiza, applied G. intraradices had better performance in severe salinity (10 dS-1 and increased seed yield and seed number per plant by 28.5 and 47.6%, respectively in comparision control. The results suggested that mycorrhizal inoculation improves water absorption by plant. Yield increases of plants under different salinity regimes dependent on their mycorrhizal inoculation.

  15. Stress concentration factors for an internally pressurized circular vessel containing a radial U-notch

    International Nuclear Information System (INIS)

    Carvalho, E.A. de

    2005-01-01

    This paper evaluates the stress concentration factors for an internally pressurized cylinder containing a radial U-notch along its length. This work studies the cases where the external to internal radius ratio (Ψ) is equal to 1.26, 1.52, 2.00, and 3.00 and the notch radius to internal radius ratio (Φ) is fixed and equal to 0.026. The U-notch depth varies from 0.1 to 0.6 of the wall thickness. Results are also presented for a fixed size semi-circular notch. Hoop stresses at the external wall are presented, showing regions where the stress matches the nominal one and the favourable places to install strain sensors. The finite element method is used to determine the stress concentration factors (K t ) for the above described situations and for a special case where a varying semi-circular notch is present with Ψ=3.00. This notch depth varies from 0.013 to 0.3 of the wall thickness. It is pointed out that even relatively small notches introduce large stress concentrations and disrupt the hoop stress distribution all over the cross section. Results are also compared to an example found in the literature for semi-circular notches and K t curves for both cases present the same shape

  16. Stress distributions due to hydrogen concentrations in electrochemically charged and aged austenitic stainless steel

    International Nuclear Information System (INIS)

    Rozenak, P.; Loew, A.

    2008-01-01

    As a result of hydrogen concentration gradients in type austenitic stainless steels, formed during electrochemical charging and followed by hydrogen loss during aging, at room temperature, surface stresses were developed. These stresses were measured by X-ray technique and the crack formation thus induced could be studied using equilibrium stress equations. After various electrochemical charging and aging times, X-ray diffraction patterns obtained from samples indicated that the reflected and broadened diffraction peaks are the result of the formation of a non-uniform but continuous solid solution in the austenitic matrix. Since both hydrogen penetrations during charging and hydrogen release during aging are diffusion controlled processes and huge hydrogen concentration gradients in the thin surface layer, at depths comparable with the depth of X-ray penetration, are observed. The non-uniform hydrogen concentration in the austenitic matrix, results to the non-uniform expansion of the atomic microstructure and latter inevitably leads to the development of internal stresses. The internal stresses development formulae's are very similar to those relating to non-uniform heating of the materials, where thermal stresses appear due to non-uniform expansion or contraction. The relevant well developed theory is applicable in our case of non-uniform hydrogen concentrations in a solid solution of electrochemically charged and aged austenitic matrix. A few cracks were present on the surface after some minutes of electrochemical charging and the severity of cracking increased as hydrogen was lost during subsequent aging. This is consistent with the expectation of high compressive stresses in the bulk of the specimen during charging and high tensile surface stresses (at the level of 1 x 10 11 Pa) during the aging process. These stresses can induce the formation of surface cracks during the aging process after electrochemical charging in the AISI 316 stainless steel

  17. Relationship between depression anxiety stress scale (DASS) and urinary hydroxyproline and proline concentrations in hospital workers.

    Science.gov (United States)

    Lee, Keou Won; Kim, Soo Jeong; Park, Jae Beom; Lee, Kyung Jong

    2011-01-01

    Although increased reactive oxygen species (ROS) is caused by stress accelerates collagen degradation, there was no data on the relationship between stress and urinary hydroxyproline (Hyp) and proline (Pro), a good marker of collagen degradation. The purpose of this study was to evaluate the relationship between depression, anxiety, and stress (DAS) and concentrations of urinary Hyp and Pro. 97 hospital employees aged 20 to 58 were asked to fill out comprehensive self-administrated questionnaires containing information about their medical history, lifestyle, length of the work year, shift-work and DAS. depression anxiety stress scale (DASS) was applied to evaluate chronic mental disorders. Urine samples were analyzed using high performance liquid chromatography (HPLC) with double derivatization for the assay of hydroxyproline and proline. The mean value of Hyp and Pro concentration in all subjects was 194.1 ± 113.4 μmol/g and 568.2 ± 310.7 μmol/g. DASS values and urinary Pro concentrations were differentiated by sex (female > male, p others, p < 0.05). In the stepwise multiple linear regressions, urinary Hyp and Pro concentrations were influenced by stress (Adjusted r2 = 0.051) and anxiety and job (Adjusted r2 = 0.199), respectively. We found that stress and anxiety were correlated with urinary Hyp and Pro concentrations. To identifying a definite correlation, further study in large populations will be needed.

  18. Effect of Boron Toxicity on Oxidative Stress and Genotoxicity in Wheat (Triticum aestivum L.).

    Science.gov (United States)

    Çatav, Şükrü Serter; Genç, Tuncer Okan; Kesik Oktay, Müjgan; Küçükakyüz, Köksal

    2018-04-01

    Boron (B) toxicity, which occurs in semi-arid and arid environments, can adversely affect the growth and yield of many plants. The aim of this study was to determine the effects of different concentrations of boric acid (3, 6, 9 and 12 mM) on growth, oxidative stress and genotoxicity parameters in root and shoot tissues of wheat seedlings. Our results indicate that B stress inhibits root and shoot growth of wheat in a concentration-dependent manner, and leads to increases in TBARS and H 2 O 2 contents in shoot tissue. Moreover, our findings suggest that high concentrations of B may exert a genotoxic effect on wheat. To the best of our knowledge, this is the first report to evaluate the effect of B stress on genotoxicity in both root and shoot tissues of wheat.

  19. Analysis of stress concentration in the Dutton groove regions of the Super Lightweight External Tank

    Science.gov (United States)

    Ahmed, R.

    1995-05-01

    Because the 2195 aluminum-lithium material of the super lightweight external tank (SLWT ET) has a lower toughness than the 2219 aluminum used in previous ET's, careful attention must be paid to stress concentrations. This report details the analysis performed on some of the stress concentrations in the orthogrid panels of the liquid hydrogen tank.

  20. Effects of silicon on Oryza sativa L. seedling roots under simulated acid rain stress.

    Science.gov (United States)

    Ju, Shuming; Yin, Ningning; Wang, Liping; Zhang, Cuiying; Wang, Yukun

    2017-01-01

    Silicon (Si) has an important function in reducing the damage of environmental stress on plants. Acid rain is a serious abiotic stress factor, and Si can alleviate the stress induced by acid rain on plants. Based on these assumptions, we investigated the effects of silicon on the growth, root phenotype, mineral element contents, hydrogen peroxide (H2O2) and antioxidative enzymes of rice (Oryza sativa L.) seedling roots under simulated acid rain (SAR) stress. The results showed that the combined or single effects of Si and/or SAR on rice roots depend on the concentration of Si and the pH of the SAR. The combined or single effects of a low or moderate concentration of Si (1.0 or 2.0 mM) and light SAR (pH 4.0) enhanced the growth of rice roots, and the combined effects were stronger than those of the single treatment. A high concentration of Si (4.0 mM) or severe SAR (pH 2.0) exerted deleterious effects. The incorporation of Si (1.0, 2.0 or 4.0 mM) into SAR with pH 3.0 or 2.0 promoted the rice root growth, decreased the H2O2 content, increased the Si concentration and the superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX) activities, maintained the balance of mineral element (K, Ca, Mg, Fe, Zn, and Cu) concentrations in the roots of rice seedlings compared with SAR alone. The alleviatory effects observed with a moderate concentration of Si (2.0 mM) were better than the effects obtained with a low or high concentration of Si (1.0 or 4.0 mM). The observed effects were due to disruptions in the absorption and utilization of mineral nutrients and impacts on the activity of antioxidant enzymes in roots, and this conclusion suggests that the degree of rice root damage caused by acid rain might be attributed to not only acid rain but also the level of Si in the soil.

  1. Effects of silicon on Oryza sativa L. seedling roots under simulated acid rain stress

    Science.gov (United States)

    Wang, Liping; Zhang, Cuiying; Wang, Yukun

    2017-01-01

    Silicon (Si) has an important function in reducing the damage of environmental stress on plants. Acid rain is a serious abiotic stress factor, and Si can alleviate the stress induced by acid rain on plants. Based on these assumptions, we investigated the effects of silicon on the growth, root phenotype, mineral element contents, hydrogen peroxide (H2O2) and antioxidative enzymes of rice (Oryza sativa L.) seedling roots under simulated acid rain (SAR) stress. The results showed that the combined or single effects of Si and/or SAR on rice roots depend on the concentration of Si and the pH of the SAR. The combined or single effects of a low or moderate concentration of Si (1.0 or 2.0 mM) and light SAR (pH 4.0) enhanced the growth of rice roots, and the combined effects were stronger than those of the single treatment. A high concentration of Si (4.0 mM) or severe SAR (pH 2.0) exerted deleterious effects. The incorporation of Si (1.0, 2.0 or 4.0 mM) into SAR with pH 3.0 or 2.0 promoted the rice root growth, decreased the H2O2 content, increased the Si concentration and the superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX) activities, maintained the balance of mineral element (K, Ca, Mg, Fe, Zn, and Cu) concentrations in the roots of rice seedlings compared with SAR alone. The alleviatory effects observed with a moderate concentration of Si (2.0 mM) were better than the effects obtained with a low or high concentration of Si (1.0 or 4.0 mM). The observed effects were due to disruptions in the absorption and utilization of mineral nutrients and impacts on the activity of antioxidant enzymes in roots, and this conclusion suggests that the degree of rice root damage caused by acid rain might be attributed to not only acid rain but also the level of Si in the soil. PMID:28291806

  2. Influence of wall couple stress in MHD flow of a micropolar fluid in a porous medium with energy and concentration transfer

    Directory of Open Access Journals (Sweden)

    Asma Khalid

    2018-06-01

    Full Text Available The intention here is to investigate the effects of wall couple stress with energy and concentration transfer in magnetohydrodynamic (MHD flow of a micropolar fluid embedded in a porous medium. The mathematical model contains the set of linear conservation forms of partial differential equations. Laplace transforms and convolution technique are used for computation of exact solutions of velocity, microrotations, temperature and concentration equations. Numerical values of skin friction, couple wall stress, Nusselt and Sherwood numbers are also computed. Characteristics for the significant variables on the physical quantities are graphically discussed. Comparison with previously published work in limiting sense shows an excellent agreement. Keywords: Micropolor fluid, Microrotation, MHD, Porosity, Wall couple stress, Exact solutions

  3. Stress concentrations in keyways and optimization of keyway design

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard

    2010-01-01

    Keys and keyways are one of the most common shaft–hub connections. Despite this fact very little numerical analysis has been reported. The design is often regulated by standards that are almost half a century old, and most results reported in the literature are based on experimental photoelastic...... analysis. The present paper shows how numerical finite element (FE) analysis can improve the prediction of stress concentration in the keyway. Using shape optimization and the simple super elliptical shape, it is shown that the fatigue life of a keyway can be greatly improved with up to a 50 per cent...... reduction in the maximum stress level. The design changes are simple and therefore practical to realize with only two active design parameters....

  4. The Effect of Exogenous Spermidine Concentration on Polyamine Metabolism and Salt Tolerance in Zoysiagrass (Zoysia japonica Steud) Subjected to Short-Term Salinity Stress.

    Science.gov (United States)

    Li, Shucheng; Jin, Han; Zhang, Qiang

    2016-01-01

    Salt stress, particularly short-term salt stress, is among the most serious abiotic factors limiting plant survival and growth in China. It has been established that exogenous spermidine (Spd) stimulates plant tolerance to salt stress. The present study utilized two zoysiagrass cultivars commonly grown in China that exhibit either sensitive (cv. Z081) or tolerant (cv. Z057) adaptation capacity to salt stress. The two cultivars were subjected to 200 mM salt stress and treated with different exogenous Spd concentrations for 8 days. Polyamine [diamine putrescine (Put), tetraamine spermine (Spm), and Spd], H2O2 and malondialdehyde (MDA) contents and polyamine metabolic (ADC, ODC, SAMDC, PAO, and DAO) and antioxidant (superoxide dismutase, catalase, and peroxidase) enzyme activities were measured. The results showed that salt stress induced increases in Spd and Spm contents and ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (SAMDC), and diamine oxidase (DAO) activities in both cultivars. Exogenous Spd application did not alter polyamine contents via regulation of polyamine-degrading enzymes, and an increase in polyamine biosynthetic enzyme levels was observed during the experiment. Increasing the concentration of exogenous Spd resulted in a tendency of the Spd and Spm contents and ODC, SAMDC, DAO, and antioxidant enzyme activities to first increase and then decrease in both cultivars. H2O2 and MDA levels significantly decreased in both cultivars treated with Spd. Additionally, in both cultivars, positive correlations between polyamine biosynthetic enzymes (ADC, SAMDC), DAO, and antioxidant enzymes (SOD, POD, CAT), but negative correlations with H2O2 and MDA levels, and the Spd + Spm content were observed with an increase in the concentration of exogenous Spd.

  5. Effect of transportation stress on heat shock protein 70 concentration and mRNA expression in heart and kidney tissues and serum enzyme activities and hormone concentrations of pigs.

    Science.gov (United States)

    Yu, Hong; Bao, En-Dong; Zhao, Ru-Qian; Lv, Qiong-Xia

    2007-11-01

    To determine the enzymatic and hormonal responses, heat shock protein 70 (Hsp70) production, and Hsp70 mRNA expression in heart and kidney tissues of transport-stressed pigs. 24 pigs (mean weight, 20 +/- 1 kg). Pigs were randomly placed into groups of 12 each. One group was transported for 2 hours. The other group was kept under normal conditions and used as control pigs. Sera were used to detect triiodothyronine, thyroxine, and cortisol concentrations and alanine aminotransferase, aspartate aminotransferase, and creatine kinase activities. The heart and kidneys of anesthetized pigs were harvested and frozen in liquid nitrogen for quantification of Hsp70 and Hsp70 mRNA. No significant differences were detected in serum alanine aminotransferase activity and triiodothyronine and cortisol concentrations between groups; however, the serum creatine kinase and aspartate aminotransferase activities and thyroxine concentrations were higher in transported pigs. Densitometric readings of western blots revealed that the amount of Hsp70 in heart and kidney tissues was significantly higher in transported pigs, compared with control pigs. Results of fluorescence quantitative real-time PCR assay revealed that the Hsp70 mRNA transcription in heart tissue, but not kidney tissue, was significantly higher in transported pigs, compared with control pigs. Transportation imposed a severe stress on pigs that was manifested as increased serum activities of aspartate aminotransferase and creatine kinase and increased amounts of Hsp70 and Hsp70 mRNA expression in heart and kidney tissues. Changes in serum enzyme activities were related to the tissue damage of transport-stressed pigs.

  6. Enhancement of BDNF Concentration and Restoration of the Hypothalamic-Pituitary-Adrenal Axis Accompany Reduced Depressive-Like Behaviour in Stressed Ovariectomised Rats Treated with Either Tualang Honey or Estrogen

    Directory of Open Access Journals (Sweden)

    Badriya Al-Rahbi

    2014-01-01

    Full Text Available A possible interaction between glucocorticoids and estrogen-induced increases in brain-derived-neurotrophic factor (BDNF expression in enhancing depressive-like behaviour has been documented. Here we evaluated the effects of Tualang honey, a phytoestrogen, and 17β-estradiol (E2 on the depressive-like behaviour, stress hormones, and BDNF concentration in stressed ovariectomised (OVX rats. The animals were divided into six groups: (i nonstressed sham-operated control, (ii stressed sham-operated control, (iii nonstressed OVX, (iv stressed OVX, (v stressed OVX treated with E2 (20 μg daily, sc, and (vi stressed OVX treated with Tualang honey (0.2 g/kg body weight daily, orally. Two months after surgery, the animals were subjected to social instability stress procedure followed by forced swimming test. Struggling time, immobility time, and swimming time were scored. Serum adrenocorticotropic hormone (ACTH and corticosterone levels, and the BDNF concentration were determined using commercially available ELISA kits. Stressed OVX rats displayed increased depressive-like behaviour with significantly increased serum ACTH and corticosterone levels, while the BDNF concentration was significantly decreased compared to other experimental groups. These changes were notably reversed by both E2 and Tualang honey. In conclusion, both Tualang honey and E2 mediate antidepressive-like effects in stressed OVX rats, possibly acting via restoration of hypothalamic-pituitary-adrenal axis and enhancement of the BDNF concentration.

  7. Notch size effects on high cycle fatigue limit stress of Udimet 720

    International Nuclear Information System (INIS)

    Ren Weiju; Nicholas, Theodore

    2003-01-01

    Notch size effects on the high cycle fatigue (HCF) limit stress of Ni-base superalloy Udimet 720 were investigated on cylindrical specimens with three notch sizes of the same stress concentration factor K t =2.74. The HCF limit stress corresponding to a life of 10 6 cycles was experimentally determined at a stress ratio of 0.1 and a frequency of 25 Hz at room temperature. The stresses were calculated using finite element analysis (FEA) and the specimens analyzed using scanning electron microscopy (SEM). Test results show that at the same K t value, notch size can slightly affect the HCF limit stress of U720 when notch root plasticity occurs. FEA and SEM results reveal that the notch size effects are influenced by a complicated combination of the stress and plastic strain fields at the notch tip, the nominal stress, and the effects of prior plastic deformation on fatigue crack initiation

  8. Low mercury concentration produces vasoconstriction, decreases nitric oxide bioavailability and increases oxidative stress in rat conductance artery.

    Directory of Open Access Journals (Sweden)

    Núbia Belem Lemos

    Full Text Available Mercury is an environmental pollutant that reduces nitric oxide (NO bioavailability and increases oxidative stress, having a close link with cardiovascular diseases, as carotid atherosclerosis, myocardial infarction, coronary heart disease and hypertension. One of the main sites affected by oxidative stress, which develops atherosclerosis, is the aorta. Under acute exposure to low mercury concentrations reactive oxygen species (ROS production were only reported for resistance vessels but if low concentrations of mercury also affect conductance arteries it is still unclear. We investigated the acute effects of 6 nM HgCl(2 on endothelial function of aortic rings measuring the reactivity to phenylephrine in rings incubated, or not, with HgCl(2 for 45 min, the protein expression for cyclooxygenase 2 (COX-2 and the AT1 receptor. HgCl(2 increased Rmax and pD2 to phenylephrine without changing the vasorelaxation induced by acetylcholine and sodium nitroprusside. Endothelial damage abolished the increased reactivity to phenylephrine. The increase of Rmax and pD2 produced by L-NAME was smaller in the presence of HgCl(2. Enalapril, losartan, indomethacin, furegrelate, the selective COX-2 inhibitor NS 398, superoxide dismutase and the NADPH oxidase inhibitor apocynin reverted HgCl(2 effects on the reactivity to phenylephrine, COX-2 protein expression was increased, and AT1 expression reduced. At low concentration, below the reference values, HgCl(2 increased vasoconstrictor activity by reducing NO bioavailability due to increased ROS production by NADPH oxidase activity. Results suggest that this is due to local release of angiotensin II and prostanoid vasoconstrictors. Results also suggest that acute low concentration mercury exposure, occurring time to time could induce vascular injury due to endothelial oxidative stress and contributing to increase peripheral resistance, being a high risk factor for public health.

  9. The effect of the method of application and concentration of asahi sl on the response of cucumber plants to chilling stress

    Directory of Open Access Journals (Sweden)

    Edward Borowski

    2012-12-01

    Full Text Available In pot experiments conducted on cucumber cv. Śremski F1, the effect was studied of short-term chilling stress on plants which had grown from seeds germinating in the solution of Asahi SL or treated with this biostimulator during the early growth period. The plants were grown in a phytotron at an air temperature of 27/22°C (day/night, using fluorescent light with FAR flux density of 220 μmol x m-2 x s-1 and with a photoperiod of 16/8. The biostimulator was applied using the following methods: a germination of seeds in 0.01% and 0.05% solution, b watering of plants twice with 0.01% or 0.05% solution, c spraying leaves with 0.3% or 0.5% solution. Plants sprayed with distilled water were the control. After 24 hours from foliar or root application of Asahi SL, one half of the plants from each experimental series was treated for a period of 3 days at a temperature of 12/6°C, with all the other growth conditions unchanged. The obtained results show that short-term chilling stress caused a significant increase in electrolyte leakage, free proline content and in the activity of ascorbate peroxidase in leaves, but a decrease in the content of chlorophyll, its maximum fluorescence (Fm and quantum yield (Fv/Fm, carotenoid content, stomatal conductance, transpiration, photosynthesis, leaf biomass and in the activity of catalase in leaves. Foliar or root application of Asahi SL in the pre-stress period decreased the values of the traits which increased as a result of chilling or increased those which decreased. Higher concentrations of the biostimulator solutions, applied using this method, were more effective. The application of the biostimulator during seed germination did not result in significant changes in the response of plants to chilling stress.

  10. Thermodynamic effect of elastic stress on grain boundary segregation of phosphorus in a low alloy steel

    International Nuclear Information System (INIS)

    Zheng, Lei; Lejček, Pavel; Song, Shenhua; Schmitz, Guido; Meng, Ye

    2015-01-01

    Grain boundary (GB) segregation of P in 2.25Cr1Mo steel induced by elastic stress shows that the P equilibrium concentration, after reaching the non-equilibrium concentration maximum at critical time, returns to its initial thermal equilibrium level. This finding confirms the interesting phenomenon that the effect of elastic stress on GB segregation of P is significant in kinetics while slight in thermodynamics. Through extending the “pressure” in classical theory of chemical potential to the “elastic stress”, the thermodynamic effect of elastic stress on GB segregation is studied, and the relationship between elastic stress and segregation Gibbs energy is formulated. The formulas reveal that the difference in the segregation Gibbs energy between the elastically-stressed and non-stressed states depends on the excess molar volume of GB segregation and the magnitude of elastic stress. Model calculations in segregation Gibbs energy confirm that the effect of elastic stress on the thermodynamics of equilibrium GB segregation is slight, and the theoretical analyses considerably agree with the experimental results. The confirmation indicates that the nature of the thermodynamic effect is well captured. - Highlights: • GB segregation of P after stress aging returns to its initial thermal equilibrium level. • Relationship between elastic stress and segregation energy is formulated. • Thermodynamic effect relies on excess molar volume and magnitude of elastic stress. • Effect of elastic stress on Gibbs energy of GB segregation is estimated to be slight. • Complete theory of the effect of elastic stress on grain boundary segregation is setup

  11. Evaluation of local stress and local hydrogen concentration at grain boundary using three-dimensional polycrystalline model

    International Nuclear Information System (INIS)

    Ebihara, Ken-ichi; Itakura, Mitsuhiro; Yamaguchi, Masatake; Kaburaki, Hideo; Suzudo, Tomoaki

    2010-01-01

    The decohesion model in which hydrogen segregating at grain boundaries reduces cohesive energy is considered to explain hydrogen embrittlement. Although there are several experimental and theoretical supports of this model, its total process is still unclear. In order to understand hydrogen embrittlement in terms of the decohesion model, therefore, it is necessary to evaluate stress and hydrogen concentration at grain boundaries under experimental conditions and to verify the grain boundary decohesion process. Under this consideration, we evaluated the stress and the hydrogen concentration at grain boundaries in the three-dimensional polycrystalline model which was generated by the random Voronoi tessellation. The crystallographic anisotropy was given to each grain. As the boundary conditions of the calculations, data extracted from the results calculated in the notched round-bar specimen model under the tensile test condition in which fracture of the steel specimen is observed was given to the polycrystalline model. As a result, it was found that the evaluated stress does not reach the fracture stress which was estimated under the condition of the evaluated hydrogen concentration by first principles calculations. Therefore, it was considered that the initiation of grain boundary fracture needs other factors except the stress concentration due to the crystallographic anisotropy. (author)

  12. Effects of naringin on apoptosis and oxidative stress in type 2 diabetic rats

    Science.gov (United States)

    Adelani, Isaacson; Bankole, Esther; Rotimi, Oluwakemi; Rotimi, Solomon

    2018-04-01

    Oxidative stress and apoptosis have been reported to play major roles in the pathogenesis of Type 2 Diabetes Mellitus (T2DM) through insulin resistance and β-cell dysfunction. Naringin is a citrus derived flavonoid that has been reported for its antioxidant properties. Even though effects of naringin in T2DM related oxidative stress has been reported, varying dose concentration in oxidative stress and mechanism of action involving T2DM related apoptosis is far-fetched. This research studied the effects of naringin at varying dose concentration on apoptosis, biomarkers of organ function and oxidative stress in high fat diet/low-streptozotocin-induced T2DM in albino Wistar rats. Diabetic rats were treated with naringin at 50mg/kg, 100mg/kg and 200mg/kg body weight for 21 days. Some biomarkers of organ function and oxidative stress in the animals were assayed using spectrophotometric techniques. The levels of expression of caspases and apoptotic regulators were quantified using semi-quantitative reverse transcriptase polymerase chain reaction (RT PCR). Enzyme - linked immunosorbent assay was used to determine inducible nitric oxide synthase (iNOS) level. Naringin treatment shows a dose dependent significant (plipid peroxidation, glutathione- s-transferase, glutathione peroxidase and glutathione reductase activities in the liver. Naringin treatment also showed a significant (p<0.05) increase in the expression of caspase 3 and reduction in BCL-2 as against the diabetic control. In addition, there was dose dependent decrease in plasma CO2 concentration and increase in the plasma iNOS concentration as compared to the diabetic control. This result highlights positive effect of naringin as an antioxidant, its role in apoptosis and also reverting the effects of organ damage in type 2 diabetes.

  13. Concentration-dependent metabolic effects of metformin in healthy and Fanconi anemia lymphoblast cells.

    Science.gov (United States)

    Ravera, Silvia; Cossu, Vanessa; Tappino, Barbara; Nicchia, Elena; Dufour, Carlo; Cavani, Simona; Sciutto, Andrea; Bolognesi, Claudia; Columbaro, Marta; Degan, Paolo; Cappelli, Enrico

    2018-02-01

    Metformin (MET) is the drug of choice for patients with type 2 diabetes and has been proposed for use in cancer therapy and for treating other metabolic diseases. More than 14,000 studies have been published addressing the cellular mechanisms affected by MET. However, several in vitro studies have used concentrations of the drug 10-100-fold higher than the plasmatic concentration measured in patients. Here, we evaluated the biochemical, metabolic, and morphologic effects of various concentrations of MET. Moreover, we tested the effect of MET on Fanconi Anemia (FA) cells, a DNA repair genetic disease with defects in energetic and glucose metabolism, as well as on human promyelocytic leukemia (HL60) cell lines. We found that the response of wild-type cells to MET is concentration dependent. Low concentrations (15 and 150 µM) increase both oxidative phosphorylation and the oxidative stress response, acting on the AMPK/Sirt1 pathway, while the high concentration (1.5 mM) inhibits the respiratory chain, alters cell morphology, becoming toxic to the cells. In FA cells, MET was unable to correct the energetic/respiratory defect and did not improve the response to oxidative stress and DNA damage. By contrast, HL60 cells appear sensitive also at 150 μM. Our findings underline the importance of the MET concentration in evaluating the effect of this drug on cell metabolism and demonstrate that data obtained from in vitro experiments, that have used high concentrations of MET, cannot be readily translated into improving our understanding of the cellular effects of metformin when used in the clinical setting. © 2017 Wiley Periodicals, Inc.

  14. Effects of Exogenous Melatonin on Methyl Viologen-Mediated Oxidative Stress in Apple Leaf

    Directory of Open Access Journals (Sweden)

    Zhiwei Wei

    2018-01-01

    Full Text Available Oxidative stress is a major source of damage of plants exposed to adverse environments. We examined the effect of exogenous melatonin (MT in limiting of oxidative stress caused by methyl viologen (MV; paraquatin in apple leaves (Malus domestica Borkh.. When detached leaves were pre-treated with melatonin, their level of stress tolerance increased. Under MV treatment, melatonin effectively alleviated the decrease in chlorophyll concentrations and maximum potential Photosystem II efficiency while also mitigating membrane damage and lipid peroxidation when compared with control leaves that were sprayed only with water prior to the stress experiment. The melatonin-treated leaves also showed higher activities and transcripts of antioxidant enzymes superoxide dismutase, peroxidase, and catalase. In addition, the expression of genes for those enzymes was upregulated. Melatonin-synthesis genes MdTDC1, MdT5H4, MdAANAT2, and MdASMT1 were also upregulated under oxidative stress in leaves but that expression was suppressed in response to 1 mM melatonin pretreatment during the MV treatments. Therefore, we conclude that exogenous melatonin mitigates the detrimental effects of oxidative stress, perhaps by slowing the decline in chlorophyll concentrations, moderating membrane damage and lipid peroxidation, increasing the activities of antioxidant enzymes, and changing the expression of genes for melatonin synthesis.

  15. Chronic stress alters concentrations of corticosterone receptors in a tissue-specific manner in wild house sparrows (Passer domesticus).

    Science.gov (United States)

    Lattin, Christine R; Romero, L Michael

    2014-07-15

    The physiological stress response results in release of glucocorticoid hormones such as corticosterone (CORT). Whereas short-term activation of this response helps animals cope with environmental stressors, chronic activation can result in negative effects including metabolic dysregulation and reproductive failure. However, there is no consensus hormonal profile of a chronically stressed animal, suggesting that researchers may need to look beyond hormone titers to interpret the impacts of chronic stress. In this study, we brought wild house sparrows (Passer domesticus) into captivity. We then compared glucocorticoid and mineralocorticoid receptor concentrations in sparrows exposed either to a standardized chronic stress protocol (n=26) or to standard husbandry conditions (controls; n=20). We used radioligand binding assays to quantify receptors in whole brain, liver, kidneys, spleen, gonads, gastrocnemius and pectoralis muscle, omental and subcutaneous fat, and bib and back skin. In most tissues, CORT receptors did not differ between controls and stressed animals, although we found marginal increases in receptor density in kidney and testes in stressed birds at some time points. Only in pectoralis muscle was there a robust effect of chronic stress, with both receptor types higher in stressed animals. Increased pectoralis sensitivity to CORT with chronic stress may be part of the underlying mechanism for muscle wasting in animals administered exogenous CORT. Furthermore, the change in pectoralis was not paralleled by gastrocnemius receptors. This difference may help explain previous reports of a greater effect of CORT on pectoralis than on other muscle types, and indicate that birds use this muscle as a protein reserve. © 2014. Published by The Company of Biologists Ltd.

  16. Influence of wall couple stress in MHD flow of a micropolar fluid in a porous medium with energy and concentration transfer

    Science.gov (United States)

    Khalid, Asma; Khan, Ilyas; Khan, Arshad; Shafie, Sharidan

    2018-06-01

    The intention here is to investigate the effects of wall couple stress with energy and concentration transfer in magnetohydrodynamic (MHD) flow of a micropolar fluid embedded in a porous medium. The mathematical model contains the set of linear conservation forms of partial differential equations. Laplace transforms and convolution technique are used for computation of exact solutions of velocity, microrotations, temperature and concentration equations. Numerical values of skin friction, couple wall stress, Nusselt and Sherwood numbers are also computed. Characteristics for the significant variables on the physical quantities are graphically discussed. Comparison with previously published work in limiting sense shows an excellent agreement.

  17. Effect of Salinity Stress on Concentrations of Nutrition Elements in Almond (Prunus Dulcis 'Shokofeh', 'Sahand' Cultivars and '13-40' Genotype Budded on GF677 Rootstock

    Directory of Open Access Journals (Sweden)

    A. Momenpour

    2016-02-01

    Full Text Available Introduction: Almond (Prunus amygdalus B. is one of the most important crops consumed as a dry fruit and it is mainly adaptable to arid and semi-arid regions mostly suffering from salinity stress (8. Soils with dry humidity regime are dominant in Iran and in the world at large and mostly include regions with more evaporation than precipitation. This in turn leads to increased salinity of the soil (9 and 10. Based on available reports, roughly 12.5% of land areas in Iran are saline, which overwhelmingly contain sodium, while more than 800 million hectares of land area on the earth (6% of overall global land area are affected by salinity (9 and 10. Therefore, compound of rootstock and scion may be used as one of the influence factors in sensitivity or tolerance to salinity of planted fruit trees including almonds (8 and 11. In recent years, for various reasons including the uniformity of trees, instead of sexual rootstock, vegetative rootstock is used. Rootstock GF677 an inter-specific hybrid (Almond Peach is propagated asexually as clone (8. It has been reported that rootstock GF677 is tolerant to salinity while rootstock nemagard (P. persica X P. davidiana is sensitive to salinity (16. It has been reported that rootstock GF677 tolerated salinity (5.5 ds/m, (19 or 5.2 ds/m (17 and 14.However, as plant species and different cultivars within the same plant species vary considerably in their tolerance to salinity (10, properly selecting plants and/or cultivars that can be grown well under adverse conditions, created in the root zone by salinization, is the most efficient and environmentally friendly agricultural practice for a more permanent solution of the problem of salinity (10. Despite the presence of information on the effect of salinity on concentration of nutrition elements of almond cultivars leaves and roots, tolerantscion/rootstock combinationshave not been introduced for this plant. Therefore, the aim of the present study is to

  18. Chronic stress effects and their reversibility on the Fallopian tubes and uterus in rats.

    Science.gov (United States)

    Divyashree, S; Yajurvedi, H N

    2018-01-01

    The durational effects of chronic stress on the Fallopian tubes and uterus were studied by exposing rats to stressors in the form of restraint (1h) and forced swimming (15min) daily for 4, 8 or 12 weeks. One group of stressed rats from each time period was then maintained without exposure to stressors for a further 4 weeks to assess their ability to recover from stress. All time periods of stress exposure resulted in decreased weight of the body and Fallopian tubes; however, the relative weight of the uterus and serum concentrations of oestradiol and insulin increased significantly. The antioxidant potential was decreased with increased malondialdehyde concentrations in the Fallopian tubes following all durations of exposure and after 4 and 8 weeks of stress exposure in the uterus. Interestingly, rats stressed for 12 weeks showed an increase in serum testosterone concentration and antioxidant enzyme activities with a decrease in malondialdehyde concentration in the uterus. The antioxidant enzyme activities and malondialdehyde concentration in the Fallopian tubes of all recovery group rats were similar to stressed rats. However, in the uterus these parameters were similar to controls in recovery group rats after 4 weeks or 8 weeks of exposure, but after 12 weeks of stress exposure these parameters did not return to control levels following the recovery period. These results reveal, for the first time, that chronic stress elicits an irreversible decrease in antioxidant defence in the Fallopian tubes irrespective of exposure duration, whereas the uterus develops reversible oxidative stress under short-term exposure but increased antioxidant potential with endometrial proliferation following long-term exposure.

  19. Effect of nitrogen concentration on temperature dependent mechanical properties of vanadium

    International Nuclear Information System (INIS)

    Carlson, O.N.; Rehbein, D.K.

    1979-01-01

    The critical resolved shear stress and strain rate sensitivity of vanadium were determined for vanadium-nitrogen alloys over the temperature range of 77K to 400K for concentrations of 1 to 500 wt ppm nitrogen. The concentration dependence of the hardening rate agrees quite well with either the Fleischer or Labusch strengthening model but the combined temperature and concentration dependence follows more closely the form predicted by Ono and Sommer. The strain rate sensitivity exhibits a peak at 140K which decreases with increasing nitrogen content but above 250K there is a reversal in this effect. (orig.) [de

  20. Study of the effect of the stress on CdTe nuclear detectors

    International Nuclear Information System (INIS)

    Ayoub, M.; Radley, I.; Mullins, J. T.; Hage-Ali, M.

    2013-01-01

    CdTe detectors are commonly used for X and γ ray applications. The performance of these detectors is strongly affected by different types of mechanical stress; such as that caused by differential expansion between the semiconductor and its intimate metallic contacts and that caused by applied pressure during the bonding process. The aim of this work was to study the effects of stress on the performance of CdTe detectors. A difference in expansion coefficients induces transverse stress under the metallic contact, while contact pressure induces longitudinal stress. These stresses have been simulated by applying known static pressures. For the longitudinal case, the pressure was applied directly to the metallic contact; while in the transverse case, it was applied to the side. We have studied the effect of longitudinal and transverse stresses on the electrical characteristics including leakage current measurements and γ-ray detection performance. We have also investigated induced defects, their nature, activation energies, cross sections, and concentrations under the applied stress by using photo-induced current transient spectroscopy and thermoelectric effect spectroscopy techniques. The operational stress limit is also given

  1. Study of the effect of the stress on CdTe nuclear detectors

    Energy Technology Data Exchange (ETDEWEB)

    Ayoub, M.; Radley, I.; Mullins, J. T. [Kromek, Thomas Wright way, TS21 3FD, Sedgefield, County Durham (United Kingdom); Hage-Ali, M. [CLEA, Airport road, Beirut (Lebanon)

    2013-09-14

    CdTe detectors are commonly used for X and γ ray applications. The performance of these detectors is strongly affected by different types of mechanical stress; such as that caused by differential expansion between the semiconductor and its intimate metallic contacts and that caused by applied pressure during the bonding process. The aim of this work was to study the effects of stress on the performance of CdTe detectors. A difference in expansion coefficients induces transverse stress under the metallic contact, while contact pressure induces longitudinal stress. These stresses have been simulated by applying known static pressures. For the longitudinal case, the pressure was applied directly to the metallic contact; while in the transverse case, it was applied to the side. We have studied the effect of longitudinal and transverse stresses on the electrical characteristics including leakage current measurements and γ-ray detection performance. We have also investigated induced defects, their nature, activation energies, cross sections, and concentrations under the applied stress by using photo-induced current transient spectroscopy and thermoelectric effect spectroscopy techniques. The operational stress limit is also given.

  2. Effects of Gibberellic Acid and Nitrogen on Some Physiology Parameters and Micronutrients Concentration in Pistachio under Salt Stress

    Directory of Open Access Journals (Sweden)

    vahid mozafari

    2017-02-01

    Full Text Available Introduction: Salinity is one of the main problems which limits crop production, especially in arid and semi-arid areas such as Iran. Iran is the most important producer of pistachio in the world. However, its performance is low in many areas. Most pistachio plantations are irrigated with saline water and with low quality (28. On the other hand, nitrogen is a dynamic element which is a constituent of amino acids, proteins, nucleic acids and Enzymes and it has a vital role in plant physiology, growth, chlorophyll formation and production of fruit and seeds (34. Gibberellic acid is known as phytohormon which varied physiological responses in plants under stress. acid gibberellic increases the photosynthesis and growth under stress and impact on the physiology and metabolism of plant (29. Based on previous studies, production and activity of plant hormones are affected by natural factors and plant nutrient requirements and the nitrogen has an important influence on production and transmission of acid gibberellic plant shoot. Therefore, in this study the effect of acid gibberellic and nitrogen on some characteristics of physiology parameters and micronutrient pistachio seedlings (Cv. Qazvini under saline conditions was studied. Materials and methods: Experiment under greenhouse condition and factorial in a completely randomized design with three replications was conducted in greenhouse agriculture college, Vali-E-Asr University of Rafsanjan. Treatments consisted of three levels of salinity (0, 1000 and 2000 mg of sodium chloride per kg of soil, three levels of nitrogen (0, 75 and 150 mg per kg of ammonium nitrate source and three acid gibberellic levels (0, 250 and 500 mg per liter. Adequate soil with little available salinity conditions was collected from the top 30-cm layer of a pistachio-culture region of Kerman province. After air drying and ground through passing a 2 mm sieve, some of the physical-chemical properties of this soil include pH (7

  3. [Effects of exogenous salicylic acid on seed germination and physiological characteristics of Coronilla varia under drought stress.

    Science.gov (United States)

    Ma, Le Yuan; Chen, Nian Lai; Han, Guo Jun; Li, Liang

    2017-10-01

    This research investigated the effects of different concentrations (0, 0.5, 1.0, 2.0 mmol·L -1 ) of salicylic acid on the seed germination and physiological characteristics of legume forage Coronilla varia (cultivar 'Lvbaoshi') under PEG-6000 (concentration 8% and 12%) simulated drought stress. The results showed that under drought stress, 0.5-1.0 mmol·L -1 salicylic acid significantly increased germination percentage, germination vigour, germination index, vitality index and bud length of C. varia. Under the stress of 12% PEG, the dry mass of C. varia seedlings processed by 1.0 mmol·L -1 salicylic acid was significantly higher than that under drought stress. 0.5-1.0 mmol·L -1 salicylic acid processing significantly increased proline, soluble protein content, the activities of catalase, peroxidase and superoxide dismutase of C. varia seedlings under drought stress, but cell electrolyte permeability, H2O2 content and O2 - · production rate of seedlings were significantly decreased. 1.0 mmol·L -1 salicylic acid produced the best results. When the concentration of salicylic acid was beyond 2.0 mmol·L -1 , no mitigation effect was observed on the seed germination and growth of seedlings under drought stress. It was concluded that salicylic acid at appropriate concentrations could effectively improve osmotic regulation, antioxidation and mitigate the damage of drought stress so as to promote the growth of C. varia seedlings.

  4. Effects of Electromagnetic Radiation Exposure on Stress-Related Behaviors and Stress Hormones in Male Wistar Rats

    Science.gov (United States)

    Mahdavi, Seyed Mohammad; Sahraei, Hedayat; Yaghmaei, Parichehreh; Tavakoli, Hassan

    2014-01-01

    Studies have demonstrated that electromagnetic waves, as the one of the most important physical factors, may alter cognitive and non-cognitive behaviors, depending on the frequency and energy. Moreover, non-ionizing radiation of low energy waves e.g. very low frequency waves could alter this phenomenon via alterations in neurotransmitters and neurohormones. In this study, short, medium, and long-term exposure to the extremely low frequency electromagnetic field (ELF-EMF) (1 and 5 Hz radiation) on behavioral, hormonal, and metabolic changes in male Wistar rats (250 g) were studied. In addition, changes in plasma concentrations for two main stress hormones, noradrenaline and adrenocorticotropic hormone (ACTH) were evaluated. ELF-EMF exposure did not alter body weight, and food and water intake. Plasma glucose level was increased and decreased in the groups which exposed to the 5 and 1Hz wave, respectively. Plasma ACTH concentration increased in both using frequencies, whereas nor-adrenaline concentration showed overall reduction. At last, numbers of rearing, sniffing, locomotor activity was increased in group receiving 5 Hz wave over the time. In conclusions, these data showed that the effects of 1 and 5 Hz on the hormonal, metabolic and stress-like behaviors may be different. Moreover, the influence of waves on stress system is depending on time of exposure. PMID:25489427

  5. Effects of electromagnetic radiation exposure on stress-related behaviors and stress hormones in male wistar rats.

    Science.gov (United States)

    Mahdavi, Seyed Mohammad; Sahraei, Hedayat; Yaghmaei, Parichehreh; Tavakoli, Hassan

    2014-11-01

    Studies have demonstrated that electromagnetic waves, as the one of the most important physical factors, may alter cognitive and non-cognitive behaviors, depending on the frequency and energy. Moreover, non-ionizing radiation of low energy waves e.g. very low frequency waves could alter this phenomenon via alterations in neurotransmitters and neurohormones. In this study, short, medium, and long-term exposure to the extremely low frequency electromagnetic field (ELF-EMF) (1 and 5 Hz radiation) on behavioral, hormonal, and metabolic changes in male Wistar rats (250 g) were studied. In addition, changes in plasma concentrations for two main stress hormones, noradrenaline and adrenocorticotropic hormone (ACTH) were evaluated. ELF-EMF exposure did not alter body weight, and food and water intake. Plasma glucose level was increased and decreased in the groups which exposed to the 5 and 1Hz wave, respectively. Plasma ACTH concentration increased in both using frequencies, whereas nor-adrenaline concentration showed overall reduction. At last, numbers of rearing, sniffing, locomotor activity was increased in group receiving 5 Hz wave over the time. In conclusions, these data showed that the effects of 1 and 5 Hz on the hormonal, metabolic and stress-like behaviors may be different. Moreover, the influence of waves on stress system is depending on time of exposure.

  6. Choir versus Solo Singing: Effects on Mood, and Salivary Oxytocin and Cortisol Concentrations.

    Science.gov (United States)

    Schladt, T Moritz; Nordmann, Gregory C; Emilius, Roman; Kudielka, Brigitte M; de Jong, Trynke R; Neumann, Inga D

    2017-01-01

    The quantification of salivary oxytocin (OXT) concentrations emerges as a helpful tool to assess peripheral OXT secretion at baseline and after various challenges in healthy and clinical populations. Both positive social interactions and stress are known to induce OXT secretion, but the relative influence of either of these triggers is not well delineated. Choir singing is an activity known to improve mood and to induce feelings of social closeness, and may therefore be used to investigate the effects of positive social experiences on OXT system activity. We quantified mood and salivary OXT and cortisol (CORT) concentrations before, during, and after both choir and solo singing performed in a randomized order in the same participants (repeated measures). Happiness was increased, and worry and sadness as well as salivary CORT concentrations were reduced, after both choir and solo singing. Surprisingly, salivary OXT concentrations were significantly reduced after choir singing, but did not change in response to solo singing. Salivary OXT concentrations showed high intra-individual stability, whereas salivary CORT concentrations fluctuated between days within participants. The present data indicate that the social experience of choir singing does not induce peripheral OXT secretion, as indicated by unchanged salivary OXT levels. Rather, the reduction of stress/arousal experienced during choir singing may lead to an inhibition of peripheral OXT secretion. These data are important for the interpretation of future reports on salivary OXT concentrations, and emphasize the need to strictly control for stress/arousal when designing similar experiments.

  7. Effects of work and life stress on semen quality.

    Science.gov (United States)

    Janevic, Teresa; Kahn, Linda G; Landsbergis, Paul; Cirillo, Piera M; Cohn, Barbara A; Liu, Xinhua; Factor-Litvak, Pam

    2014-08-01

    To evaluate associations between work-related stress, stressful life events, and perceived stress and semen quality. Cross-sectional analysis. Northern California. 193 men from the Child Health and Development Studies evaluated between 2005-2008. None. Measures of stress including job strain, perceived stress, and stressful life events; outcome measures of sperm concentration, percentage of motile sperm, and percentage of morphologically normal sperm. We found an inverse association between perceived stress score and sperm concentration (estimated coefficient b=-0.09×10(3)/mL; 95% confidence interval [CI]=-0.18, -0.01), motility (b=-0.39; 95% CI=-0.79, 0.01), and morphology (b=-0.14; 95% CI, -0.25, -0.04) in covariate-adjusted linear regression analyses. Men who experienced two or more stressful life events in the past year compared with no stressful events had a lower percentage of motile sperm (b=-8.22; 95% CI, -14.31, -2.13) and a lower percentage of morphologically normal sperm (b=-1.66; 95% CI, -3.35, 0.03) but a similar sperm concentration. Job strain was not associated with semen parameters. In this first study to examine all three domains of stress, perceived stress and stressful life events but not work-related stress were associated with semen quality. Copyright © 2014 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  8. [Study on the health effect of the occupational stress in aircrew].

    Science.gov (United States)

    Zhou, L P; Tian, H E; Liu, L L; Ma, L; Zhang, H; Zhang, Q D; Zhu, X Y; Zhu, H B

    2017-02-20

    Objective: To explore the relationship between occupational stress and physiological and biochemical indexes, to research the health effect of the occupational stress in aircrew. Methods: 450 aircrews were conducted with the OSI-R questionnaire survey, examine the level of blood pressure, blood routine, ALT and UA. Results: The concentration of HB was positively related with task conflict and entertainment and leisure ( β =0.262 and 0.106, both P stress reactions were negatively related with HB ( β =-0.163, -0.102, and -0.137, all P stress reactions and social support were negatively related with RBC ( β =-0.157, -0.119, and -0.113, all P stress reactions and social support had a negative relationship with ALT ( β =-0.176, -0.096, and -0.102, all P stress reactions and social support were negatively related with SBP ( β =-0.093, -0.103, and -0.111, all P Occupational stress of the aircrew is significantly related with blood pressure, RBC, ALT and UA, occupational stress can make effects on the health of aircrew.

  9. Effects of iron concentration and redox states on failure of boron-free ...

    Indian Academy of Sciences (India)

    Effects of iron concentration and redox states on failure of boron-free E-glass fibres under applied stress in different conditions ... Materials, Donghua University, Shanghai 201620, China; Material Research Center, Missouri University of Science and Technology, Rolla 65409, USA; Fiber Glass Science and Technology, ...

  10. Effects of acute and chronic psychological stress on platelet aggregation in mice.

    Science.gov (United States)

    Matsuhisa, Fumikazu; Kitamura, Nobuo; Satoh, Eiki

    2014-03-01

    Although psychological stress has long been known to alter cardiovascular function, there have been few studies on the effect of psychological stress on platelets, which play a pivotal role in cardiovascular disease. In the present study, we investigated the effects of acute and chronic psychological stress on the aggregation of platelets and platelet cytosolic free calcium concentration ([Ca(2+)]i). Mice were subjected to both transportation stress (exposure to novel environment, psychological stress) and restraint stress (psychological stress) for 2 h (acute stress) or 3 weeks (2 h/day) (chronic stress). In addition, adrenalectomized mice were subjected to similar chronic stress (both transportation and restraint stress for 3 weeks). The aggregation of platelets from mice and [Ca(2+)]i was determined by light transmission assay and fura-2 fluorescence assay, respectively. Although acute stress had no effect on agonist-induced platelet aggregation, chronic stress enhanced the ability of the platelet agonists thrombin and ADP to stimulate platelet aggregation. However, chronic stress failed to enhance agonist-induced increase in [Ca(2+)]i. Adrenalectomy blocked chronic stress-induced enhancement of platelet aggregation. These results suggest that chronic, but not acute, psychological stress enhances agonist-stimulated platelet aggregation independently of [Ca(2+)]i increase, and the enhancement may be mediated by stress hormones secreted from the adrenal glands.

  11. Effect of Camphorquinone Concentration in Physical-Mechanical Properties of Experimental Flowable Resin Composites

    Directory of Open Access Journals (Sweden)

    Dayany da Silva Alves Maciel

    2018-01-01

    Full Text Available The aim of this study was to evaluate the effect of camphorquinone concentration in physical-mechanical properties of experimental flowable composites in order to find the concentration that results in maximum conversion, balanced mechanical strength, and minimum shrinkage stress. Model composites based on BISGMA/TEGDMA with 70% wt filler loading were prepared containing different concentrations of camphorquinone (CQ on resin matrix (0.25%, 0.50%, 1%, 1.50%, and 2% by weight. Degree of conversion was determined by FTIR. Surface hardness was assessed before and after 24 h ethanol storage and softening rate was determined. Depth of cure was determined by Knoop hardness evaluation at different depths. Color was assessed by reflectance spectrophotometer, employing the CIE-Lab system. Flexural strength and elastic modulus were determined by a three-point bending test. Shrinkage stress was determined in a Universal Testing Machine in a high compliance system. Data were submitted to ANOVA and Tukey’s test (α = 0.05. The increase in CQ concentration caused a significant increase on flexural strength and luminosity of composites. Surface hardness was not affected by the concentration of CQ. Composite containing 0.25% wt CQ showed lower elastic modulus and shrinkage stress when compared to others. Depth of cure was 3 mm for composite containing 1% CQ and 2 mm for the other tested composites. Degree of conversion was inversely correlated with softening rate and directly correlated with elastic modulus and shrinkage stress. In conclusion, CQ concentration affects polymerization characteristics and mechanical strength of composites. The concentration of CQ in flowable composite for optimized polymerization and properties was 1% wt of the resin matrix, which allows adequate balance among degree of conversion, depth of cure, mechanical properties, and color characteristics of these materials.

  12. A study on fatigue crack growth behavior subjected to a single tensile overload: Part II. Transfer of stress concentration and its role in overload-induced transient crack growth

    International Nuclear Information System (INIS)

    Lee, S.Y.; Choo, H.; Liaw, P.K.; An, K.; Hubbard, C.R.

    2011-01-01

    The combined effects of overload-induced enlarged compressive residual stresses and crack tip blunting with secondary cracks are suggested to be responsible for the observed changes in the crack opening load and resultant post-overload transient crack growth behavior [Lee SY, Liaw PK, Choo H, Rogge RB, Acta Mater 2010;59:485-94]. In this article, in situ neutron diffraction experiments were performed to quantify the influence of the combined effects by investigating the internal-stress evolution at various locations away from the crack tip. In the overload-retardation period, stress concentration occurs in the crack blunting region (an overload point) until a maximum crack arrest load is reached. The stress concentration is then transferred from the blunting region to the propagating crack tip (following the overload), requiring a higher applied load, as the closed crack is gradually opened. The transfer phenomena of the stress concentration associated with a crack opening process account for the nonlinearity of strain response in the vicinity of the crack tip. The delaying action of stress concentration at the crack tip is understood in conjunction with the concept of a critical stress (i.e. the stress required to open the closed crack behind the crack tip). A linear relationship between Δε eff and ΔK eff provides experimental support for the hypothesis that ΔK eff can be considered as the fatigue crack tip driving force.

  13. Biological effects of laser-induced stress waves

    International Nuclear Information System (INIS)

    Doukas, A.; Lee, S.; McAuliffe, D.

    1995-01-01

    Laser-induced stress waves can be generated by one of the following mechanisms: Optical breakdown, ablation or rapid heating of an absorbing medium. These three modes of laser interaction with matter allow the investigation of cellular and tissue responses to stress waves with different characteristics and under different conditions. The most widely studied phenomena are those of the collateral damage seen in photodisruption in the eye and in 193 run ablation of cornea and skin. On the other hand, the therapeutic application of laser-induced stress waves has been limited to the disruption of noncellular material such as renal stones, atheromatous plaque and vitreous strands. The effects of stress waves to cells and tissues can be quite disparate. Stress waves can fracture tissue, damage cells, and increase the permeability of the plasma membrane. The viability of cell cultures exposed to stress waves increases with the peak stress and the number of pulses applied. The rise time of the stress wave also influences the degree of cell injury. In fact, cell viability, as measured by thymidine incorporation, correlates better with the stress gradient than peak stress. Recent studies have also established that stress waves induce a transient increase of the permeability of the plasma membrane in vitro. In addition, if the stress gradient is below the damage threshhold, the cells remain viable. Thus, stress waves can be useful as a means of drug delivery, increasing the intracellular drug concentration and allowing the use of drugs which are impermeable to the cell membrane. The present studies show that it is important to create controllable stress waves. The wavelength tunability and the micropulse structure of the free electron laser is ideal for generating stress waves with independently adjustable parameters, such as rise time, duration and peak stress

  14. Effects of a chronic stress treatment on vaccinal response in lambs.

    Science.gov (United States)

    Destrez, A; Boissy, A; Guilloteau, L; Andanson, S; Souriau, A; Laroucau, K; Chaillou, E; Deiss, V

    2017-05-01

    Farming systems can expose animals to chronic mild stress which is known to induce negative affective state. Affective state in animals, as in humans, can be assessed through behavioral cues. This study aimed to describe the effect of a chronic mild stress, known to induce a negative affective state, on sheep health through their response to vaccination. The study used 15 lambs subjected to a model of chronic mild stress for 15 weeks and 15 lambs reared under conventional farming as a control group. After 7 weeks of stressful treatment, the lambs were individually exposed to a judgment bias test to assess a putative stress-induced 'pessimism.' After 15 weeks of stressful treatment, antibody immune response was measured after an injection of a live vaccine challenge (Chlamydia abortus attenuated vaccine strain 1B). Stressed lambs displayed a pessimistic-like perception in the judgment bias test, revealing a negative affective state. Stressed and control animals showed different immunological reactions to vaccine challenge: stressed sheep had lower hemoglobin concentrations and higher platelet, granulocyte and acute-phase protein concentrations. Antibody response induced by the vaccine strain was not different between stressed and control sheep. Our results suggest that negative affective state induced by chronic stress treatment may induce a stronger inflammatory response to vaccine challenge in sheep. Improvement of animal health may be achieved through consideration of stressors that may affect the emotional and immunological state of sheep.

  15. The effect of academic stress and attachment stress on stress-eaters and stress-undereaters.

    Science.gov (United States)

    Emond, Michael; Ten Eycke, Kayla; Kosmerly, Stacey; Robinson, Adele Lafrance; Stillar, Amanda; Van Blyderveen, Sherry

    2016-05-01

    It is well established that stress is related to changes in eating patterns. Some individuals are more likely to increase their overall food intake under conditions of stress, whereas others are more likely to consume less food when stressed. Attachment style has been linked to disordered eating and eating disorders; however, comparisons of eating behaviors under attachment versus other types of stress have yet to be explored. The present laboratory study examined the eating patterns in self-identified stress-undereaters and stress-eaters under various types of stress. More specifically, the study examined the effects of academic and attachment stress on calorie, carbohydrate and sugar consumption within these two groups. Under the guise of critiquing student films, university students viewed either one of two stress-inducing videos (academic stress or attachment stress, both designed to be emotionally arousing) or a control video (designed to be emotionally neutral), and their food intake was recorded. Results demonstrated that the video manipulations were effective in inducing stress. Differential patterns of eating were noted based on group and stress condition. Specifically, stress-undereaters ate fewer calories, carbohydrates and sugars than stress-eaters in the academic stress condition, but not in the attachment stress or control condition. Findings suggest that specific types of stressors may influence eating behaviors differently. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Effect of military training stress on plasma adrenomedullin (ADM) levels in recruits

    International Nuclear Information System (INIS)

    Zheng Hong; Luo Nanping

    2009-01-01

    Objective: To investigate the effect of military training stress on the secretion and metabolism of adrenomedullin in recruits. Methods: Plasma ADM (with RIA) and urinary VMA (with colorimetric analysis) contents were determined both before and after 1h strenuous military exercise in 60 newly enlisted soldiers and once in 50 soliders served over 3 years (as controls). Results: For the recruits group, the plasma concentrations of ADM and urinary concentrations of VMA both before and after military training were significantly higher than those in veterans control (P<0.05, P<0.01, P<0.05, P<0.01). High strength military training resulted in significant elevation of concentrations of both ADM and VMA (P<0.01, P<0.05). The elevation of plasma ADM concentration was extremely significant with an amplitude about 9 times (23.72 ± 12.63 pg/ml before training and 214.97 ± 57.75 pg/ml after training). Conclusion: 1) The stress of enrollment and military training may result in increase of secretion of ADM and VMA in recruits. 2) Appropriate stress is beneficial in terms of rapid adaptation for changes of internal and external environment, while excessive acute and repeated stress may be harmful. (authors)

  17. Oxidative stress biomarkers and their relationship with cytokine concentrations in overweight/obese pregnant women and their neonates.

    Science.gov (United States)

    Hernández-Trejo, María; Montoya-Estrada, Araceli; Torres-Ramos, Yessica; Espejel-Núñez, Aurora; Guzmán-Grenfell, Alberto; Morales-Hernández, Rosa; Tolentino-Dolores, Maricruz; Laresgoiti-Servitje, Estibalitz

    2017-01-07

    Oxidative damage present in obese/overweight mothers may lead to further oxidative stress conditions or inflammation in maternal and cord blood samples. Thirty-four pregnant women/newborn pairs were included in this study to assess the presence of oxidative stress biomarkers and their relationship with serum cytokine concentrations. Oxidative stress biomarkers and antioxidant enzymes were compared between the mother/offspring pairs. The presence of 27 cytokines was measured in maternal and cord blood samples. Analyses were initially performed between all mothers and newborns and later between normal weight and mothers with overweight and obesity, and diabetic/non-diabetic women. Significant differences were found in biomarker concentrations between mothers and newborns. Additionally, superoxide-dismutase activity was higher in pre-pregnancy overweight mothers compared to those with normal weight. Activity for this enzyme was higher in neonates born from mothers with normal pregestational weight compared with their mothers. Nitrites in overweight/obese mothers were statistically lower than in their offspring. Maternal free fatty acids, nitrites, carbonylated proteins, malondialdehyde and superoxide dismutase predicted maternal serum concentrations of IL-4, IL-13, IP-10 and MIP-1β. Arginase activity in maternal plasma was related to decreased concentrations of IL-4 and IL-1β in cord arterial blood. Increased maternal malondialdehyde plasma was associated with higher levels of IL-6 and IL-7 in the offspring. Oxidative stress biomarkers differ between mothers and offspring and can predict maternal and newborn cytokine concentrations, indicating a potential role for oxidative stress in foetal metabolic and immunologic programming. Moreover, maternal obesity and diabetes may affect maternal microenvironments, and oxidative stress related to these can have an impact on the placenta and foetal growth.

  18. [Effects of occupational stress on serum tumor necrosis factor-α and interleukins].

    Science.gov (United States)

    Zhou, Wen-Hui; Yu, Shan-Fa; Jiang, Kai-You

    2010-12-01

    To explore the effect of occupational stress on serum tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-2 and IL-4. A cross-sectional epidemiological study was conducted in 200 workers from the refrigerator assembly line in Henan province in China. Psychosocial work conditions were measured by using the job demand-control model, the effort-reward imbalance model questionnaires and occupational stress measurement scale. Serum TNF-α, IL-1β, IL-2, and IL-4 concentrations were measured by radioimmunoassay or immunoradiometric assay method respectively. Serum TNF-α concentration was statistically significantly different between workers with higher affective balance level and control groups [(1.947 ± 0.173) and (2.029 ± 0.240) fmol/ml] (P life stress level and control groups [(1.759 ± 0.361) and (1.606 ± 0.381) ng/ml] (P life stress and role ambiguity were the predictors of serum IL-2 (R(2) was 0.040, 0.078 and 0.104, respectively). Reward was the predictor of serum IL-4 (R(2) = 0.030). Unhealthy psychological stress factor might be induce a marked increase in the concentrations of serum TNF-α, IL-1β, IL-2, as well as IL-4.

  19. Effect of dissolved hydrogen concentration on IASCC initiation susceptibility of type 316 stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Min-Jae; Kim, Sung Woo; Hwang, Seong Sik [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    The effect of DH concentration on PWSCC of nickel based alloys has been studied, higher dissolved hydrogen strategy is being considered to obtain partial mitigation of PWSCC. In the case of stainless steels, it is necessary to research the effect of DH concentration on irradiation assisted stress corrosion cracking(IASCC). In this research, we tried to evaluate the effect of DH concentration on IASCC initiation susceptibility using the proton irradiated type 316 stainless steels under the condition of simulated primary water. The slow strain rate tests were performed using the proton irradiated type 316 stainless steels at the simulated primary water conditions, crack length per unit area for all tested specimens were calculated. IASCC initiation susceptibility was increased by increasing irradiation doses and by increasing DH concentration.

  20. Stress concentration factors for integral and pad reinforced nozzles in spherical pressure vessels subjected to radial load and moment

    International Nuclear Information System (INIS)

    Soliman, S.F.; Gill, S.S.

    1979-01-01

    Charts are presented giving the elastic stress concentration factors in spherical pressure vessels with pad and integral reinforcement for radial branches subjected to radial load and moment. The effect of all the geometrical parameters is discussed, including the limitations of thin shell theory on the validity of the results. (author)

  1. Effect of psychological stress on the L-arginine-nitric oxide pathway and semen quality

    Directory of Open Access Journals (Sweden)

    S. Eskiocak

    2006-05-01

    Full Text Available It has been reported that mental stress causes abnormality of spermiogram parameters. We investigated the effect of psychological stress on the L-arginine-nitric oxide (NO pathway. Semen samples were collected from 29 healthy fourth semester medical students just before (stress and 3 months after (non-stress the final examinations. Psychological stress was measured by the State Anxiety Inventory questionnaire. After standard semen analysis, arginase activity and NO concentration were measured spectrophotometrically in the seminal plasma. Measurements were made in duplicate. During the stress period, sperm concentration (41.28 ± 3.70 vs 77.62 ± 7.13 x 10(6/mL, rapid progressive motility of spermatozoa (8.79 ± 1.66 vs 20.86 ± 1.63% and seminal plasma arginase activity (0.12 ± 0.01 vs 0.22 ± 0.01 U/mL were significantly lower than in the non-stress situation, whereas seminal plasma NO (17.28 ± 0.56 vs 10.02 ± 0.49 µmol/L was higher compared to the non-stress period (P < 0.001 for all. During stress there was a negative correlation between NO concentration and sperm concentration, the percentage of rapid progressive motility and arginase activity (r = -0.622, P < 0.01; r = -0.425, P < 0.05 and r = -0.445, P < 0.05, respectively. These results indicate that psychological stress causes an increase of NO level and a decrease of arginase activity in the L-arginine-NO pathway. Furthermore, poor sperm quality may be due to excessive production of NO under psychological stress. In the light of these results, we suggest that the arginine-NO pathway, together with arginase and NO synthase, are involved in semen quality under stress conditions.

  2. Effect study of multi-bubbles on stress distribution of fuel particle

    International Nuclear Information System (INIS)

    Zhao Yi; Wang Xiaomin; Long Chongsheng

    2015-01-01

    The finite element model was proposed to simulate the process of the UO_2 dispersion fuel particle sustaining the internal pressure of multi-bubbles, and the stress distribution of fuel particle with intra-bubbles was calculated. The results show that when the bubbles line equidistantly along x axis, the max normal stress along y axis increases with the number of bubbles, meanwhile, the increment of the normal stress gradually decreases. There is a limit that the effect of bubble's number imposes on the max normal stress in the fuel particle. When multi-column of bubbles exist, the max normal stress along x axis in the fuel particle increases, and the max normal stress along y axis decreases with the increase of the number of bubble column. The stress concentration in the fuel particle decreases with the spacing radius ratio increasing. (authors)

  3. Concentration of stresses and strains in a notched cyclinder of a viscoplastic material under harmonic loading

    Science.gov (United States)

    Zhuk, Ya A.; Senchenkov, I. K.

    1999-02-01

    Certain aspects of the correct definitions of stress and strain concentration factors for elastic-viscoplastic solids under cyclic loading are discussed. Problems concerning the harmonic kinematic excitation of cylindrical specimens with a lateral V-notch are examined. The behavior of the material of a cylinder is modeled using generalized flow theory. An approximate model based on the concept of complex moduli is used for comparison. Invariant characteristics such as stress and strain intensities and maximum principal stress and strain are chosen as constitutive quantities for concentration-factor definitions. The behavior of time-varying factors is investigated. Concentration factors calculated in terms of the amplitudes of the constitutive quantities are used as representative characteristics over the cycle of vibration. The dependences of the concentration factors on the loads are also studied. The accuracy of Nueber's and Birger's formulas is evaluated. The solution of the problem in the approximate formulation agrees with its solution in the exact formulation. The possibilities of the approximate model for estimating low-cycle fatigue are evaluated.

  4. The Effect of Music on the Human Stress Response

    Science.gov (United States)

    Thoma, Myriam V.; La Marca, Roberto; Brönnimann, Rebecca; Finkel, Linda; Ehlert, Ulrike; Nater, Urs M.

    2013-01-01

    Background Music listening has been suggested to beneficially impact health via stress-reducing effects. However, the existing literature presents itself with a limited number of investigations and with discrepancies in reported findings that may result from methodological shortcomings (e.g. small sample size, no valid stressor). It was the aim of the current study to address this gap in knowledge and overcome previous shortcomings by thoroughly examining music effects across endocrine, autonomic, cognitive, and emotional domains of the human stress response. Methods Sixty healthy female volunteers (mean age = 25 years) were exposed to a standardized psychosocial stress test after having been randomly assigned to one of three different conditions prior to the stress test: 1) relaxing music (‘Miserere’, Allegri) (RM), 2) sound of rippling water (SW), and 3) rest without acoustic stimulation (R). Salivary cortisol and salivary alpha-amylase (sAA), heart rate (HR), respiratory sinus arrhythmia (RSA), subjective stress perception and anxiety were repeatedly assessed in all subjects. We hypothesized that listening to RM prior to the stress test, compared to SW or R would result in a decreased stress response across all measured parameters. Results The three conditions significantly differed regarding cortisol response (p = 0.025) to the stressor, with highest concentrations in the RM and lowest in the SW condition. After the stressor, sAA (p=0.026) baseline values were reached considerably faster in the RM group than in the R group. HR and psychological measures did not significantly differ between groups. Conclusion Our findings indicate that music listening impacted the psychobiological stress system. Listening to music prior to a standardized stressor predominantly affected the autonomic nervous system (in terms of a faster recovery), and to a lesser degree the endocrine and psychological stress response. These findings may help better understanding the

  5. Running Reduces Uncontrollable Stress-Evoked Serotonin and Potentiates Stress-Evoked Dopamine Concentrations in the Rat Dorsal Striatum.

    Directory of Open Access Journals (Sweden)

    Peter J Clark

    Full Text Available Accumulating evidence from both the human and animal literature indicates that exercise reduces the negative consequences of stress. The neurobiological etiology for this stress protection, however, is not completely understood. Our lab reported that voluntary wheel running protects rats from expressing depression-like instrumental learning deficits on the shuttle box escape task after exposure to unpredictable and inescapable tail shocks (uncontrollable stress. Impaired escape behavior is a result of stress-sensitized serotonin (5-HT neuron activity in the dorsal raphe (DRN and subsequent excessive release of 5-HT into the dorsal striatum following exposure to a comparatively mild stressor. However, the possible mechanisms by which exercise prevents stress-induced escape deficits are not well characterized. The purpose of this experiment was to test the hypothesis that exercise blunts the stress-evoked release of 5-HT in the dorsal striatum. Changes to dopamine (DA levels were also examined, since striatal DA signaling is critical for instrumental learning and can be influenced by changes to 5-HT activity. Adult male F344 rats, housed with or without running wheels for 6 weeks, were either exposed to tail shock or remained undisturbed in laboratory cages. Twenty-four hours later, microdialysis was performed in the medial (DMS and lateral (DLS dorsal striatum to collect extracellular 5-HT and DA before, during, and following 2 mild foot shocks. We report wheel running prevents foot shock-induced elevation of extracellular 5-HT and potentiates DA concentrations in both the DMS and DLS approximately 24 h following exposure to uncontrollable stress. These data may provide a possible mechanism by which exercise prevents depression-like instrumental learning deficits following exposure to acute stress.

  6. Effect of Salicylic Acid on the Growth and Physiological Characteristics of Maize under Stress Conditions

    International Nuclear Information System (INIS)

    Manzoor, K.; Ilyas, N.; Batool, N.; Arshad, M.; Ahmad, B.

    2015-01-01

    Salicylic acid (SA) is a naturally occurring signaling molecule and growth regulator that enhances plant growth particularly in stress conditions. The present study was planned to evaluate the effects of different levels of SA on maize growth under drought and salt stress conditions. An experiment was conducted to test the morphological, physiological and biochemical changes in two cultivar of maize D-1184 and TG-8250. Varying levels of salicylic acid, i.e. 5mM, 10mM and 15mM were applied through foliar method. Exogenous applications of salicylic acid were done after 20 days of germination of the maize plants. Salicylic acid significantly affects root and shoot dry matter under drought and salt stress. Foliar application of SA significantly increased proline concentration (11 percentage and 12 percentage), amino acid accumulation (25 percentage and 18 percentage), relative water (17 percentage and 14 percentage) and Chlorophyll content. Overall, it can be concluded that SA at lower concentration is effective to minimize the effect of stress conditions. Maize cultivar TG-8250 showed better tolerance under drought and salt stress condition as compared to D-1184 cultivar. (author)

  7. Overall bolt stress optimization

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard

    2013-01-01

    The state of stress in bolts and nuts with International Organization for Standardization metric thread design is examined and optimized. The assumed failure mode is fatigue, so the applied preload and the load amplitude together with the stress concentrations define the connection strength....... Maximum stress in the bolt is found at the fillet under the head, at the thread start, or at the thread root. To minimize the stress concentration, shape optimization is applied. Nut shape optimization also has a positive effect on the maximum stress. The optimization results show that designing a nut......, which results in a more evenly distribution of load along the engaged thread, has a limited influence on the maximum stress due to the stress concentration at the first thread root. To further reduce the maximum stress, the transition from bolt shank to the thread must be optimized. Stress reduction...

  8. Effects of Cu stress on maize seedlings using X-ray energy spectrum and FTIR spectra methods

    International Nuclear Information System (INIS)

    Qiao Lin; Fu Zhaolin; Qiao Chuanying

    2011-01-01

    The effects of Cu 2+ stress on maize seedlings by using scanning electron microscope, X-ray energy spectrum and Fourier transform infrared attenuated total reflection (FTIR-ATR) spectrometry were investigated, and antioxidative enzymes activities such as SOD, CAT, POD, APX were measured. Results showed that, with the increasing of Cu concentration, the content of chlorophyll decreased, and antioxidative enzyme activities increased at first and then decreased at higher concentration stress. High concentration Cu 2+ treatment twisted the cells' shape and increased copper content on leaf surface, and absorption of other nutrients were also affected. The result of FTIR-ATR analysis showed that the organic content of leaf were changed by Cu 2+ stress. (authors)

  9. Modulating effect of the nootropic drug, piracetam on stress- and subsequent morphine-induced prolactin secretion in male rats.

    Science.gov (United States)

    Matton, A.; Engelborghs, S.; Bollengier, F.; Finné, E.; Vanhaeist, L.

    1996-01-01

    1. The effect of the nootropic drug, piracetam on stress- and subsequent morphine-induced prolactin (PRL) secretion was investigated in vivo in male rats, by use of a stress-free blood sampling and drug administration method by means of a permanent indwelling catheter in the right jugular vein. 2. Four doses of piracetam were tested (20, 100, 200 and 400 mg kg-1), being given intraperitoneally 1 h before blood sampling; control rats received saline instead. After a first blood sample, rats were subjected to immobilization stress and received morphine, 6 mg kg-1, 90 min later. 3. Piracetam had no effect on basal plasma PRL concentration. 4. While in the non-piracetam-treated rats, stress produced a significant rise in plasma PRL concentration, in the piracetam-pretreated rats PRL peaks were attenuated, especially in the group given 100 mg kg-1 piracetam, where plasma PRL concentration was not significantly different from basal values. The dose-response relationship showed a U-shaped curve; the smallest dose had a minor inhibitory effect and the highest dose had no further effect on the PRL rise. 5. In unrestrained rats, morphine led to a significant elevation of plasma PRL concentration. After the application of immobilization stress it lost its ability to raise plasma PRL concentration in the control rats, but not in the piracetam-treated rats. This tolerance was overcome by piracetam in a significant manner but with a reversed dose-response curve; i.e. the smaller the dose of piracetam, the higher the subsequent morphine-induced PRL peak. 6. There is no simple explanation for the mechanism by which piracetam induces these contradictory effects. Interference with the excitatory amino acid system, which is also involved in opiate action, is proposed speculatively as a possible mediator of the effects of piracetam. PMID:8821540

  10. The effect of water stress and salinity on growth and physiology of tomato (Lycopersicon esculentum Mil.

    Directory of Open Access Journals (Sweden)

    Giannakoula Anastasia E.

    2013-01-01

    Full Text Available Carotenoids like lycopene are important pigments found in photosynthetic pigment-protein complexes in plants. They are responsible for the bright colors of fruits and vegetables and perform various functions in photosynthesis. Our research has shown that the application of moderate salt stress on tomato plants can enhance lycopene and potentially other antioxidant concentrations in fruits. The increase in lycopene in response to salt stress in the tomato fruits varied from 20% to 80%. Although the specific biological mechanisms involved in increasing fruit lycopene deposition has not been clearly elucidated, evidence suggests that increasing antioxidant concentrations is a primary physiological response of the plant to salt stress. Additionally drought stress during cultivation increased the antioxidant capacity of tomato fruit while maintaining the lycopene concentration. In addition, the effects of silicium were investigated, added to the nutrient solution either at low concentration or at an increased concentration. The present study clearly indicates that an enhanced silicium supply to tomato increases markedly the lycopene contents, irrespective of the salinity status in the tomato fruit.

  11. Bimodal effect of oxidative stress in internal anal sphincter smooth muscle

    Science.gov (United States)

    Singh, Jagmohan; Kumar, Sumit

    2015-01-01

    Changes in oxidative stress may affect basal tone and relaxation of the internal anal sphincter (IAS) smooth muscle in aging. We examined this issue by investigating the effects of the oxidative stress inducer 6-anilino-5,8-quinolinedione (LY-83583) in basal as well as U-46619-stimulated tone, and nonadrenergic, noncholinergic (NANC) relaxation in rat IAS. LY-83583, which works via generation of reactive oxygen species in living cells, produced a bimodal effect in IAS tone: lower concentrations (0.1 nM to 10 μM) produced a concentration-dependent increase, while higher concentrations (50–100 μM) produced a decrease in IAS tone. An increase in IAS tone by lower concentrations was associated with an increase in RhoA/Rho kinase (ROCK) activity. This was evident by the increase in RhoA/ROCK in the particulate fractions, in ROCK activity, and in the levels of phosphorylated (p) Thr696-myosin phosphatase target subunit 1 and pThr18/Ser19-20-kDa myosin light chain. Conversely, higher concentrations of LY-83583 produced inhibitory effects on RhoA/ROCK. Interestingly, both the excitatory and inhibitory effects of LY-83583 in the IAS were reversed by superoxide dismutase. The excitatory effects of LY-83583 were found to resemble those with neuronal nitric oxide synthase (nNOS) inhibition by l-NNA, since it produced a significant increase in the IAS tone and attenuated NANC relaxation. These effects of LY-83583 and l-NNA were reversible by l-arginine. This suggests the role of nNOS inhibition and RhoA/ROCK activation in the increase in IAS tone by LY-83583. These data have important implications in the pathophysiology and therapeutic targeting of rectoanal disorders, especially associated with IAS dysfunction. PMID:26138467

  12. Remote sensing of soybean stress as an indicator of chemical concentration of biosolid amended surface soils

    Science.gov (United States)

    Sridhar, B. B. Maruthi; Vincent, Robert K.; Roberts, Sheila J.; Czajkowski, Kevin

    2011-08-01

    The accumulation of heavy metals in the biosolid amended soils and the risk of their uptake into different plant parts is a topic of great concern. This study examines the accumulation of several heavy metals and nutrients in soybeans grown on biosolid applied soils and the use of remote sensing to monitor the metal uptake and plant stress. Field and greenhouse studies were conducted with soybeans grown on soils applied with biosolids at varying rates. The plant growth was monitored using Landsat TM imagery and handheld spectroradiometer in field and greenhouse studies, respectively. Soil and plant samples were collected and then analyzed for several elemental concentrations. The chemical concentrations in soils and roots increased significantly with increase in applied biosolid concentrations. Copper (Cu) and Molybdenum (Mo) accumulated significantly in the shoots of the metal-treated plants. Our spectral and Landsat TM image analysis revealed that the Normalized Difference Vegetative Index (NDVI) can be used to distinguish the metal stressed plants. The NDVI showed significant negative correlation with increase in soil Cu concentrations followed by other elements. This study suggests the use of remote sensing to monitor soybean stress patterns and thus indirectly assess soil chemical characteristics.

  13. Beneficial effects of CO2 enrichment to field-grown soybeans under ozone stress

    International Nuclear Information System (INIS)

    Lee, E.H.; Mulchi, C.L.

    1991-01-01

    Damage from gaseous air pollution [e.g. ozone (O 3 ) and sulfur dioxide (SO 2 )] on crops in the US has been estimated to exceed several billion dollars annually. Atmospheric carbon dioxide (CO 2 ) concentrations have increased from about 290 ppm in the late 1800's to current levels of 350 ppm. The combined effects of increased CO 2 and O 3 stress have not been studied under field conditions. The present study was conducted to determine the interactive effects of CO 2 enrichment and O 3 stress on the growth and physiology of 'Clark' soybean, testing the hypothesis that elevated CO 2 will ameliorate the effects of O 3 stress. Experiments with soybeans in open-top field chambers showed that increasing CO 2 levels to 400 parts per million (ppm) negated current ambient ozone harmful effects on soybean yields. When ambient O 3 levels were doubled, it was necessary to increase the atmospheric CO 2 concentration to 500 ppm to negate O 3 damage. Rising CO 2 counteracts O 3 pollution. Reduced stomatal conductance and decreased photosynthesis appear to reverse the CO 2 stimulation

  14. Effects of fiber ellipticity and orientation on dynamic stress concentrations in porous fiber-reinforced composites

    Science.gov (United States)

    Hasheminejad, Seyyed M.; Sanaei, Roozbeh

    2007-11-01

    Interaction of time harmonic fast longitudinal and shear incident plane waves with an elliptical fiber embedded in a porous elastic matrix is studied. The novel features of Biot dynamic theory of poroelasticity along with the classical method of eigen-function expansion and the pertinent boundary conditions are employed to develop a closed form series solution involving Mathieu and modified Mathieu functions of complex arguments. The complications arising due to the non-orthogonality of angular Mathieu functions corresponding to distinct wave numbers in addition to the problems associated with appearance of additional angular dependent terms in the boundary conditions are all avoided by expansion of the angular Mathieu functions in terms of transcendental functions and subsequent integration, leading to a linear set of independent equations in terms of the unknown scattering coefficients. A MATHEMATICA code is developed for computing the Mathieu functions in terms of complex Fourier coefficients which are themselves calculated by numerically solving appropriate sets of eigen-systems. The analytical results are illustrated with numerical examples in which an elastic fiber of elliptic cross section is insonified by a plane fast compressional or shear wave at normal incidence. The effects of fiber cross sectional ellipticity, angle of incidence (fiber two-dimensional orientation), and incident wave polarization (P, SV, SH) on dynamic stress concentrations are studied in a relatively wide frequency range. Limiting cases are considered and fair agreements with well-known solutions are established.

  15. Prenatal maternal stress in relation to the effects of prenatal lead exposure on toddler cognitive development.

    Science.gov (United States)

    Zhou, Leilei; Xu, Jian; Zhang, Jinsong; Yan, Chonghuai; Lin, Yanfen; Jia, Yinan; Hu, Wenjing

    2017-03-01

    To evaluate the effects of maternal lead exposure during pregnancy on toddler cognitive development and the potential effect modification by maternal stress. We conducted a prospective birth-cohort study in Shanghai from 2010 to 2012 and investigated 225 mother-infant pairs. The mothers were recruited in mid-to-late pregnancy and children were followed up until 24-36 months old. A self-administered Symptom Checklist-90-Revised Scale (SCL-90-R) was used to assess maternal emotional stress during pregnancy. Maternal whole blood lead levels were measured during gestational weeks 28-36. The toddlers' cognitive levels were assessed using the Gesell Development Scale. Multiple linear regression models were established to explore the main effects of prenatal lead exposure on toddlers' cognitive abilities and the modifying effects of maternal stress. Covariate information was collected through interviews, questionnaires and medical records. The mean maternal blood lead concentration was 3.30 (95%CI: 3.05, 3.57) μg/dL. After adjusting for relevant confounders, no significant associations of maternal blood lead concentrations with toddlers' cognitive levels were observed in all five domains of the Gesell scale (P>0.05). However, the interaction between prenatal maternal blood lead and stress was significant in the domains of adaptive behavior, language and social behavior. When stratified by maternal stress levels, compared with non-significant associations (P>0.05) among low (P1-P75) prenatal stress group, adverse associations between maternal blood lead concentrations (log10-transformed) and toddlers' cognitive levels were observed among high (P75-P100) prenatal stress group in the domains of language (β=-33.82, 95%CI: -60.04, -7.59), social behavior (β=-41.00, 95%CI: -63.11, -18.89) and adaptive behavior (β=-17.93, 95%CI: -35.83, -0.03). Prenatal maternal stress may exacerbate the deleterious effects of prenatal exposure to lead on toddler cognitive development

  16. Ultraviolet-B and water stress effects on growth, gas exchange and oxidative stress in sunflower plants.

    Science.gov (United States)

    Cechin, Inês; Corniani, Natália; de Fátima Fumis, Terezinha; Cataneo, Ana Catarina

    2008-07-01

    The effects and interaction of drought and UV-B radiation were studied in sunflower plants (Helianthus annuus L. var. Catissol-01), growing in a greenhouse under natural photoperiod conditions. The plants received approximately 1.7 W m(-2) (controls) or 8.6 W m(-2) (+UV-B) of UV-B radiation for 7 h per day. The UV-B and water stress treatments started 18 days after sowing. After a period of 12 days of stress, half of the water-stressed plants (including both UV-B irradiated or non-irradiated) were rehydrated. Both drought and UV-B radiation treatments resulted in lower shoot dry matter per plant, but there was no significant interaction between the two treatments. Water stress and UV-B radiation reduced photosynthesis, stomatal conductance and transpiration. However, the amplitude of the effects of both stressors was dependent on the interactions. This resulted in alleviation of the negative effect of drought on photosynthesis and transpiration by UV-B radiation as the water stress intensified. Intercelluar CO(2) concentration was initially reduced in all treatments compared to control plants but it increased with time. Photosynthetic pigments were not affected by UV-B radiation. Water stress reduced photosynthetic pigments only under high UV-B radiation. The decrease was more accentuated for chlorophyll a than for chlorophyll b. As a measure for the maximum efficiency of photosystem II in darkness F (v)/F (m) was used, which was not affected by drought stress but initially reduced by UV-B radiation. Independent of water supply, UV-B radiation increased the activity of pirogalol peroxidase and did not increase the level of malondialdehyde. On the other hand, water stress did not alter the activity of pirogalol peroxidase and caused membrane damage as assessed by lipid peroxidation. The application of UV-B radiation together with drought seemed to have a protective effect by lowering the intensity of lipid peroxidation caused by water stress. The content of proline

  17. Finite element analysis of stress concentration in three popular brands of fiber posts systems used for maxillary central incisor teeth.

    Science.gov (United States)

    Aggarwal, Shalini; Garg, Vaibhav

    2011-07-01

    To study the stress concentrations in endodontically treated maxillary central incisor teeth restored with 3 different fiber post systems subjected to various oblique occlusal loads. FEM analysis was used to analyze stress concentrations generated in maxillary anterior teeth. Computer aided designing was used to create a 2-D model of an upper central incisor. Post systems analyzed were the DT Light Post (RDT, Bisco), Luscent Anchor (Dentatus) & RelyX (3M-ESPE). The entire design assembly was subjected to analysis by ANSYS for oblique loading forces of 25N, 80N & 125 N RESULTS: The resultant data showed that the RelyX generated the least amount of stress concentration. Minimal stress buildups contribute to the longevity of the restorations. Thus RelyX by virtue of judicious stress distribution is the better option for restoration of grossly decayed teeth.

  18. Effects of dissolved carbon dioxide on energy metabolism and stress responses in European seabass (Dicentrarchus labrax)

    NARCIS (Netherlands)

    Santos, G.A.; Schrama, J.W.; Capelle, J.; Rombout, J.H.W.M.; Verreth, J.A.J.

    2013-01-01

    Elevated carbon dioxide concentrations reduce feed intake and growth in several fish species and induce stress responses. In this study, the effects of moderately elevated CO2 levels on performance, energy partitioning, swimming activity and stress response in European seabass were assessed.

  19. Effect of stress at dosing on organophosphate and heavy metal toxicity

    International Nuclear Information System (INIS)

    Jortner, Bernard S.

    2008-01-01

    This paper reviews recent studies assessing the effect of well-defined, severe, transient stress at dosing on two classical models of toxicity. These are the acute (anticholinesterase) toxicity seen following exposure to the organophosphate insecticide chlorpyrifos, and the nephrotoxicity elicited by the heavy metal depleted uranium, in rats. Stress was induced by periods of restraint and forced swimming in days to weeks preceding toxicant exposure. Forced swimming was far more stressful, as measured by marked, if transient, elevation of plasma corticosterone. This form of stress was administered immediately prior to administration of chlorpyrifos or depleted uranium. Chlorpyrifos (single 60 mg/kg subcutaneously) elicited marked inhibition of brain acetylcholinesterase 4-day post-dosing. Depleted uranium (single intramuscular doses of 0.1, 0.3 or 1.0 mg/kg uranium) elicited dose-dependent increase in kidney concentration of the metal, with associated injury to proximal tubular epithelium and increases in serum blood urea nitrogen and creatinine during the 30-day post-dosing period. Stress at dosing had no effect on these toxicologic endpoints

  20. Effects of different concentrations of pollen extract on brain tissues of Oncorhynchus mykiss

    Directory of Open Access Journals (Sweden)

    Mehmet Fuat Gulhan

    2014-03-01

    Full Text Available Objective: To determine the antioxidant capacities of pollen extract applied at different concentrations on biochemical parameters in brain tissues of rainbow trouts. Methods: The effective concentration of pollen was determined with some biochemical parameters in brain tissues of fish treated at various concentrations of the pollen extract (0.5, 2.5, 5, 10, 20 and 30 mg/L for 96 h. The malondialdehyde levels, total antioxidant status, total oxidant status, oxidative stress index and amounts of total free sulfhydryl groups were analyzed in fish brain. Results: The malondialdehyde levels decreased in groups of 0.5, 2.5, 5, 10, 20 and 30 mg/L pollen-treated compared to control group (P<0.05. The highest level of total antioxidant status (P<0.05 and the lowest value (P<0.05 of the total oxidant status was 10 mg/L concentration of pollen. Oxidative stress index and level of sulfhydryl groups showed lowest values (P<0.05 in 10 mg/L pollen treated group compared with control group. Conclusions: To apply the pollen to fish reduces the detrimental effects and modulates oxidative status via activating antioxidant defense systems at brain tissue. As a result, pollen can be added up to 10 mg/L to the medium of rainbow trout to improve health of fish.

  1. Comparative Salt Stress Study on Intracellular Ion Concentration in Marine and Salt-adapted Freshwater Strains of Microalgae

    Directory of Open Access Journals (Sweden)

    Ahmad Farhad TALEBI

    2013-08-01

    Full Text Available Salinity imposes significant stresses in various living organisms including microalgae. High extracellular concentration of Na+ directly influences ionic balance inside the cell and subsequently the cellular activities. In the present study, the effect of such stress on growth and intracellular ions concentration (IIC of Dunaliella salina and Chlorella Spp. was investigated. IIC was analyzed using Ion chromatography technique. D. salina showed the highest degree of resistance to increase in salinity as little changes occurred both in IIC and in growth parameters. D. salina could maintain the balance of K+ inside the cell and eject the excess Na+ even at NaCl concentrations above 1M. Moreover, D. salina accumulated β-carotene in order to protect its photosynthetic apparatus. Among Chlorella species, C. vulgaris showed signs of adaptation to high content of salinity, though it is a fresh water species by nature. Moreover, the response shown by C. vulgaris to rise in salinity was even stronger than that of C. salina, which is presumably a salt-water resistant species. In fact, C. vulgaris could maintain intracellular K+ better than C. salina in response to increasing salinity, and as a result, it could survive at NaCl concentrations as high as 0.75 M. Marine strains such as D. salina well cope with the fluctuations in salinity through the existing adaptation mechanisms i.e. maintaining the K+/N+ balance inside the cell, K+ accumulation and Na+ ejection, accumulation of photosynthetic pigments like β-carotene.

  2. Effects of high nitrogen concentrations on the growth of submersed macrophytes at moderate phosphorus concentrations.

    Science.gov (United States)

    Yu, Qing; Wang, Hong-Zhu; Li, Yan; Shao, Jian-Chun; Liang, Xiao-Min; Jeppesen, Erik; Wang, Hai-Jun

    2015-10-15

    Eutrophication of lakes leading to loss of submersed macrophytes and higher turbidity is a worldwide phenomenon, attributed to excessive loading of phosphorus (P). However, recently, the role of nitrogen (N) for macrophyte recession has received increasing attention. Due to the close relationship between N and P loading, disentanglement of the specific effects of these two nutrients is often difficult, and some controversy still exists as to the effects of N. We studied the effects of N on submersed macrophytes represented by Vallisneria natans (Lour.) Hara in pots positioned at three depths (0.4 m, 0.8 m, and 1.2 m to form a gradient of underwater light conditions) in 10 large ponds having moderate concentrations of P (TP 0.03 ± 0.04 mg L(-1)) and five targeted concentrations of total nitrogen (TN) (0.5, 2, 10, 20, and 100 mg L(-1)), there were two ponds for each treatment. To study the potential shading effects of other primary producers, we also measured the biomass of phytoplankton (ChlaPhyt) and periphyton (ChlaPeri) expressed as chlorophyll a. We found that leaf length, leaf mass, and root length of macrophytes declined with increasing concentrations of TN and ammonium, while shoot number and root mass did not. All the measured growth indices of macrophytes declined significantly with ChlaPhyt, while none were significantly related to ChlaPeri. Neither ChlaPhyt nor ChlaPeri were, however, significantly negatively related to the various N concentrations. Our results indicate that shading by phytoplankton unrelated to the variation in N loading and perhaps toxic stress exerted by high nitrogen were responsible for the decline in macrophyte growth. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Reliability assessment of stress concentration performance state for a perforated composite plate under traction

    Directory of Open Access Journals (Sweden)

    Jabbouri A.

    2012-07-01

    Full Text Available Considering a perforated sandwich plate made from two elastic homogenous and isotropic layers, and having a square hole, reliability assessment of stress concentration limit state for which the stress should not exceed a given threshold is performed in this work. Assuming that the plate dimensions and the applied loading are deterministic, focus is done on the square hole centre position and edge length considered to be random variables. The means and the standard deviations of these variables are assumed to be known, but no information is so far available about their densities of probabilities. To assess reliability of the performance state, reliability analysis known methods are applied to a response surface representation of the stress concentration factor of the perforated plate which is obtained through quadratic polynomial regression of finite element results. A parametric study is performed regarding the influence of the distributions of probabilities chosen to model the hole dimensions uncertainties. It is shown that the probability of failure depends largely on the selected densities of probabilities.

  4. [Effects of exogenous nitric oxide on physiological characteristics of longan (Dimocarpus longana) seedlings under acid rain stress].

    Science.gov (United States)

    Liu, Jian-fu; Wang, Ming-yuan; Yang, Chen; Zhu, Ai-jun

    2013-08-01

    This paper studied the effects of exogenous nitric oxide donor sodium nitroprusside (SNP) on the chlorophyll content, antioxidant enzyme activities, and osmotic regulation substances of longan (Dimocarpus longana 'Fuyan') seedlings under acid rain (pH 3.0) stress. Under the acid rain stress, the seedling leaf superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities and chlorophyll, soluble protein and soluble sugar contents decreased obviously, while the leaf malondialdedyde content had a remarkable increase, suggesting the toxic effect of the acid rain on the seedlings. Exogenous nitric oxide had dual nature on the physiological characteristics of longan seedlings under acid rain stress. Applying 0.1-0.5 mmol x L(-1) of SNP improved the SOD, POD and CAT activities and the chlorophyll, soluble protein and soluble sugar contents significantly, and decreased the malondialdedyde content. Low concentrations SNP reduced the oxidative damage caused by the acid rain stress, and 0.5 mmol x L(-1) of SNP had the best effect. Under the application of 0.5 mmol x L(-1) of SNP, the total chlorophyll, soluble protein, and soluble sugar contents and the SOD, POD and CAT activities increased by 76.0%, 107.0%, 216.1%, 150. 0%, 350.9% and 97.1%, respectively, and the malondialdedyde content decreased by 46.4%. It was suggested that low concentration (0.1-0.5 mmol x L(-1)) SNP could alleviate the toxic effect of acid rain stress on longan seedlings via activating the leaf antioxidant enzyme activities and reducing oxidative stress, while high concentration SNP (1.0 mmol x L(-1)) lowered the mitigation effect.

  5. Prenatal noise and restraint stress interact to alter exploratory behavior and balance in juvenile rats, and mixed stress reverses these effects.

    Science.gov (United States)

    Badache, Soumeya; Bouslama, Slim; Brahmia, Oualid; Baïri, Abdel Madjid; Tahraoui, Abdel Krim; Ladjama, Ali

    2017-05-01

    We aimed to investigate in adolescent rats the individual and combined effects of prenatal noise and restraint stress on balance control, exploration, locomotion and anxiety behavior. Three groups of pregnant rats were exposed to daily repeated stress from day 11 to day 19 of pregnancy: 3 min noise (Noise Stress, NS); 10 min restraint (restraint stress, RS); or 3 min noise followed by 10 min restraint (mixed stress, MS). On postnatal days (PND) 44, 45 and 46, four groups of male rats (Control, NS, RS:, MS; 16 rats each), were tested as follows: (1) beam walking (BW), (2) open field (OF) and (3) elevated plus maze (EPM). Our results show that the NS group had significantly impaired balance control, locomotion and both horizontal and vertical exploration (p time in EPM open arms: p time to complete BW: p < .05). Hence, combined prenatal stressors exert non-additive effects on locomotion, exploration and balance control, but induce greater anxiety through additive effects. Terminal plasma ACTH concentration was increased by prenatal stress, especially noise, which group had the largest adrenal glands. Overall, contrary to expectation, combined prenatal stressors can interact to increase anxiety level, but diminish alteration of exploration, locomotion and impaired balance control, which were strongly induced by noise stress. Lay summary: Experience of stress in pregnancy can have negative effects on the offspring that are long-lasting. Here, we used laboratory rats to see whether repeated episodes of exposure to loud noise or preventing free movement, alone or together, during pregnancy had different effects on behaviors of the adolescent offspring. Using standard tests, we found the prenatal stresses caused the offspring to be anxious, and not to balance when moving around as well as normal offspring; the degree of impairment depended on the type of stress - loud noise exposure had the greatest effects, but if the stresses were combined the effects

  6. Interactive effects of salinity stress and nicotinamide on physiological and biochemical parameters of Faba bean plant

    International Nuclear Information System (INIS)

    Abdelhamid, Magdi T; Sadak, Mervat Sh; Schmidhalter, Urs; El Saady, Abdel Kareem M.

    2013-01-01

    A possible survival strategy for plants under saline conditions is to use some compounds that could alleviate the salt stress effect. One of these compounds is nicotinamide (vitamin B3/niacin). The effect of exogenous application of nicotinamide with different concentrations (0,200 or 400 mg l-1) on faba bean (Vicia faba L.) plant grown at different NaCl levels (0,50 or 100 mM) was investigated in the wire house of the National Research Centre, Cairo, Egypt. Salinity stress significantly reduced the photosynthetic pigments, polysaccharides, total carbohydrates, total-N contents of shoot, plant height, leaves number, fresh and dry weights of shoot, seed yield, total carbohydrates and total crude protein of the yielded seeds compared with those of the control plants. In contrast, salinity induced marked increases in sucrose, total soluble sugars, total free amino acids, proline, lipid peroxidation product (MDA) and some oxidative enzymes (polyphenol-oxidase and peroxidase). Also, salinity stress increased Na+ contents with the decreases of other macro and micro elements contents (P, K+, Mg_2+, Ca_2+, Fe_2+, Mn_2+, Zn_2+ and Cu_2+) of shoots and the yielded seeds of faba bean. Foliar spraying of nicotinamide alleviated the adverse effects of salinity stress through increased the photosynthetic pigments, polysaccharides, total carbohydrates, total N concentration of shoot, plant height, leaves number, fresh and dry weights of shoot, and seed yield as well as, sucrose, total soluble sugars, total free amino acids and proline, compared with those of the corresponding salinity levels, while decreased lipid peroxidation product as malondialdehyde (MDA) and the oxidative enzymes (polyphenol oxidase and peroxidase enzymes). Nicotinamide inhibited the uptake of Na+ and accelerated the accumulation of P, K+, Mg_2+, Ca_2+, Fe_2+, Mn_2+, Zn_2+ and Cu_2+ concentrations in the shoots of salt stressed plants and enhanced total carbohydrate and total crude protein percentage and

  7. Hydrocortisone at stress-associated concentrations helps maintain human heart rate variability during subsequent endotoxin challenge.

    Science.gov (United States)

    Rassias, Athos J; Guyre, Paul M; Yeager, Mark P

    2011-12-01

    We evaluated the differential impact of stress-associated vs high pharmacologic concentrations of hydrocortisone pretreatment on heart rate variability (HRV) during a subsequent systemic inflammatory stimulus. Healthy volunteers were randomized to receive placebo (Control) and hydrocortisone at 1.5 μg/kg per minute (STRESS) or at 3.0 μg/kg per minute (PHARM) as a 6-hour infusion. The STRESS dose was chosen to replicate the condition of physiologic adrenal cortical output during acute systemic stress. The PHARM dose was chosen to induce a supraphysiologic concentration of cortisol. The next day, all subjects received 2 ng/kg Escherichia coli endotoxin (lipopolysaccharide). Heart rate variability was analyzed with the statistic approximate entropy (ApEn). A lower ApEn correlates with decreased HRV. At the 3-hour nadir, the decrease in ApEn in the STRESS group was significantly less compared to placebo (P statistically different. We also found that the maximal decrease in ApEn preceded maximal increase in heart rate in all groups. The decrease in R-R interval was maximal at 4 hours, whereas the ApEn nadir was 1 hour earlier at 3 hours. Pretreatment with a stress dose of hydrocortisone but not a higher pharmacologic dose maintained a significantly higher ApEn after endotoxin exposure when compared to a placebo. In addition, decreases in ApEn preceded increases in heart rate. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. Estimating water stressed dwarf green bean pigment concentration through hyperspectral indices

    International Nuclear Information System (INIS)

    Koksal, E.S.; Ustrun, H.; Ozcan, H.; Gunturk, A.

    2010-01-01

    In this study, the relationship between leaf pigment concentration (analyzed in the laboratory) and four spectral indexes (measured in the field) was investigated. For this purpose, field experiments consisting of six different irrigation treatments were conducted with dwarf green beans during 2005 growing season. Based on spectral data, spectral indexes were plotted against pigment concentration. Results showed that under water stress, the chlorophyll and carotene contents of green bean leaves rose. According to linear regression analysis between spectral indexes and pigment contents, the Normalized Difference Pigment Chlorophyll Index (NPCI) and Normalized Difference Vegetation Index (NDVI) had the highest correlations with the chlorophyll (a, b and total), and carotene content of leaves. (author)

  9. Aerodynamic effects of trees on pollutant concentration in street canyons.

    Science.gov (United States)

    Buccolieri, Riccardo; Gromke, Christof; Di Sabatino, Silvana; Ruck, Bodo

    2009-09-15

    This paper deals with aerodynamic effects of avenue-like tree planting on flow and traffic-originated pollutant dispersion in urban street canyons by means of wind tunnel experiments and numerical simulations. Several parameters affecting pedestrian level concentration are investigated, namely plant morphology, positioning and arrangement. We extend our previous work in this novel aspect of research to new configurations which comprise tree planting of different crown porosity and stand density, planted in two rows within a canyon of street width to building height ratio W/H=2 with perpendicular approaching wind. Sulfur hexafluoride was used as tracer gas to model the traffic emissions. Complementary to wind tunnel experiments, 3D numerical simulations were performed with the Computational Fluid Dynamics (CFD) code FLUENT using a Reynolds Stress turbulence closure for flow and the advection-diffusion method for concentration calculations. In the presence of trees, both measurements and simulations showed considerable larger pollutant concentrations near the leeward wall and slightly lower concentrations near the windward wall in comparison with the tree-less case. Tree stand density and crown porosity were found to be of minor importance in affecting pollutant concentration. On the other hand, the analysis indicated that W/H is a more crucial parameter. The larger the value of W/H the smaller is the effect of trees on pedestrian level concentration regardless of tree morphology and arrangement. A preliminary analysis of approaching flow velocities showed that at low wind speed the effect of trees on concentrations is worst than at higher speed. The investigations carried out in this work allowed us to set up an appropriate CFD modelling methodology for the study of the aerodynamic effects of tree planting in street canyons. The results obtained can be used by city planners for the design of tree planting in the urban environment with regard to air quality issues.

  10. Stress Concentration Factor of Expanded Aluminum Tubes Using Finite Element Modeling

    Directory of Open Access Journals (Sweden)

    L Mhamdi

    2013-06-01

    Full Text Available This paper discusses the development of semi-empirical relations for the maximum stress concentration factor (SCF around circular holes embedded in aluminum tubes under various expansion ratios and mandrel angles. Finite element models were developed to study the expansion of a typical aluminum tube with embedded holes of various sizes. An elastic perfectly-plastic material behaviour was used to describe the structural response of the tubes under expansion. Various hole-diameter-to-tubewall- thickness ratios, tube expansion ratios, and mandrel angles were considered to determine the stress state around the hole at zero and 90 degree locations from which the maximum SCF was determined. Semi-empirical relations for the maximum SCF using the Lagrange interpolation formulation were developed. The developed relations were found to predict the SCFs accurately.

  11. Subacute stress and chronic stress interact to decrease intestinal barrier function in rats.

    Science.gov (United States)

    Lauffer, Adriana; Vanuytsel, Tim; Vanormelingen, Christophe; Vanheel, Hanne; Salim Rasoel, Shadea; Tóth, Joran; Tack, Jan; Fornari, Fernando; Farré, Ricard

    2016-01-01

    Psychological stress increases intestinal permeability, potentially leading to low-grade inflammation and symptoms in functional gastrointestinal disorders. We assessed the effect of subacute, chronic and combined stress on intestinal barrier function and mast cell density. Male Wistar rats were allocated to four experimental groups (n = 8/group): 1/sham; 2/subacute stress (isolation and limited movement for 24 h); 3/chronic crowding stress for 14 days and 4/combined subacute and chronic stress. Jejunum and colon were collected to measure: transepithelial electrical resistance (TEER; a measure of epithelial barrier function); gene expression of tight junction molecules; mast cell density. Plasma corticosterone concentration was increased in all three stress conditions versus sham, with highest concentrations in the combined stress condition. TEER in the jejunum was decreased in all stress conditions, but was significantly lower in the combined stress condition than in the other groups. TEER in the jejunum correlated negatively with corticosterone concentration. Increased expression of claudin 1, 5 and 8, occludin and zonula occludens 1 mRNAs was detected after subacute stress in the jejunum. In contrast, colonic TEER was decreased only after combined stress, and the expression of tight junction molecules was unaltered. Increased mast cell density was observed in the chronic and combined stress condition in the colon only. In conclusion, our data show that chronic stress sensitizes the gastrointestinal tract to the effects of subacute stress on intestinal barrier function; different underlying cellular and molecular alterations are indicated in the small intestine versus the colon.

  12. Anti-stress effects of human placenta extract: possible involvement of the oxidative stress system in rats.

    Science.gov (United States)

    Park, Hyun-Jung; Shim, Hyun Soo; Lee, Sunyoung; Hahm, Dae Hyun; Lee, Hyejung; Oh, Chang Taek; Han, Hae Jung; Ji, Hyi Jeong; Shim, Insop

    2018-05-08

    Human placenta hydrolysate (hPH) has been utilized to improve menopausal, fatigue, liver function. Its high concentration of bioactive substances is known to produce including antioxidant, anti-inflammatory and anti-nociceptive activities. However, its mechanisms of stress-induced depression remain unknown. The present study examined the effect of hPH on stress-induced depressive behaviors and biochemical parameters in rats. hPH (0.02 ml, 0.2 ml or 1 ml/rat) was injected intravenously 30 min before the daily stress session in male Sprague-Dawley rats exposed to repeated immobilization stress (4 h/day for 7 days). The depressive-like behaviors of all groups were measured by elevated plus maze (EPM) and forced swimming test (FST). After the behavior tests, brain samples of all groups were collected for the analysis of glutathione peroxidase (GPx) and nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) staining. Treatment with hPH produced a significant decrease of immobility time in the FST compared to the controls. Additionally, hPH treatment elicited a slightly decreasing trend in anxiety behavior on the EPM. Furthermore, hPH increased the level of GPx protein in the hippocampus, and decreased the expression of NADPH-d in the paraventricular nucleus (PVN). This study demonstrated that hPH has anti-stress effects via the regulation of nitric oxide (NO) synthase and antioxidant activity in the brain. These results suggest that hPH may be useful in the treatment of stress-related diseases such as chronic fatigue syndrome.

  13. Two-dimensional simulation of the thermal stress effect on static and dynamic VDMOS characteristics

    International Nuclear Information System (INIS)

    Alwan, M.; Beydoun, B.; Ketata, K.; Zoaeter, M.

    2005-01-01

    Using a two-dimensional simulator, the effect of the thermal stress on static and dynamic vertical double-diffusion metal oxide semiconductor (VDMOS) characteristics have been investigated. The use of the device under certain thermal stress conditions can produce modifications of its physical and electrical properties. Based on physics and 2D simulations, this paper proposes an analysis of this stress effect observed on the electrical characteristics of the device. Parameters responsible of these modifications are determined. Approximate expressions of the ionization coefficients and breakdown voltage in terms of temperature are proposed. Non-punch-through junction theory is used to express the breakdown voltage and the space charge extension with respect to the impurity concentration and the temperature. The capacitances of the device have been also studied. The effect of the stress on C-V characteristics is observed and analyzed. We notice that the drain-gate, drain-source and gate-source capacitances are shifted due to the degradation of device physical properties versus thermal stress

  14. Glucose concentration and blood acid-basis status in high-yielding dairy cows during heat stress

    Directory of Open Access Journals (Sweden)

    Vujanac Ivan

    2011-01-01

    Full Text Available The objective of this work was to examine the effect of heat stress on glucose and pH values in blood of high-yielding dairy cows in the early stage of lactation, as well as to determine whether the changes in these parameters are interdependent under such conditions. An experiment was performed on high-yielding dairy cows during the summer and the spring periods. Forty cows were selected, twenty each for the two periods under investigation. In the course of the experiment, the temperature humidity index (THI was determined for the entire period of investigations, and then also the average daily THI, nightmorning THI (average value of hourly THI measured from 22h on the previous day until 10h of the current day, as well as the day-night THI (average value of hourly THI measured during the period from 10h to 22h of the current day. The pH and glucose concentration were determined in blood samples taken in the morning and afternoon of days 30, 60, and 90 of lactation during the spring and summer periods of the investigations. Based on the results for the THI, it was established that the animals were not exposed to the effect of extreme heat stress during the spring period of investigations, while they were periodically exposed to moderate but also extreme heat stress during the summer, in particular in the afternoon hours. It can be concluded from the results obtained for the blood pH that the cows were in respiratory alkalosis during the summer in the morning and afternoon hours on day 30, in the afternoon hours of days 60 and 90 of lactation, as well as in the afternoon on day 90 of lactation during the spring period of investigations. During the summer period, there were no statistically significant differences between the pH value determined in the morning and afternoon hours on day 30 of lactation, while the pH value was significantly higher in the afternoon hours than in the morning hours on days 60 and 90 of lactation. There were no

  15. Effects of organic additives on preferred plane and residual stress of copper electroplated on polyimide

    International Nuclear Information System (INIS)

    Kim, Jongsoo; Kim, Heesan

    2010-01-01

    Effects of the preferred plane and the residual stress of an electroplated copper on polyethylene glycol (PEG) and 3-N,N-dimethylaminodithiocarbamoyl-1-propanesulfonic acid (DPS) were studied. Polyimide film coated with sputtered copper was used as a substrate. Preferred plane, residual stress, and impurity level in the electroplated copper were measured by an X-ray diffractometry (XRD), calculated by Stoney's equation, and analyzed with secondary ion mass spectroscopy (SMS), respectively. With increasing the concentration of PEG, the preferred plane changed in the order (1 0 0) and (1 1 0) while with increasing the concentration of DPS, the preferred plane changed in the order (1 1 0), (1 0 0), and (1 1 1). Based on the modified preferred growth model, where the amount of additive adsorbed on a plane is newly assumed to be proportional to its surface energy in vacuum, the predicted preferred planes correspond to the experimental results. The residual stress of the electroplated copper depended on the type of additive as well as its concentration but was independent of the preferred plane. For example, PEG and DPS induced tensile and compressive residual stresses in the electroplated copper, respectively, and their magnitudes increased with their concentrations. The dependency of residual stress on the additives was explained by the incorporated additives into the electroplated copper.

  16. Effect of salt-stresses on the hormonal regulation of growth, photosynthesis and distribution of 14C - assimilates in bean plants

    International Nuclear Information System (INIS)

    Starck, Z.; Karwowska, R.

    1978-01-01

    The experiments were carried out to study the effect of salt-stresses and ABA on the growth photosynthesis and translocation of assimilates in bean plants. It was planned to reduce the content of GA 3 and cytokinins and increase ABA content in salinized plants. The results show that salt-stress (NaCl and concentrated nutrient solution), reduces all the investigated processes in a different degree. NaCl-stress retarded most seriously growth of apical part and blades in contrast to 7-times concentrated nutrient solution decreasing mainly the rate of root and blade growth. Photosynthesis and 14 C-translocation of 14 C-assimilates were retarded more seriously by NaCl than by 7-times concentrated nutrient solution. In the case of seriously stressed plants GA 3 and cytokinins (more effectively) reversed the negative effect of stress conditions both on the photosynthesis and on the 14 C-translocation. On the basis of the obtained results, it seems that changes in the rate of investigated processes in salinized plants are due to hormonal disturbances which cause directly or indirectly retardation of photosynthesis and translocation of assimilates. (author)

  17. Effect of salt-stresses on the hormonal regulation of growth, photosynthesis and distribution of 14C-assimilates in bean plants

    Directory of Open Access Journals (Sweden)

    Z. Starck

    2015-01-01

    Full Text Available The experiments were carried out to study the effect of salt-stresses and ABA on the growth, photosynthesis and translocation of assimilates in bean plants. It was planed to reduce the content of GA3 and cytokinins and increase ABA content in salinized plants. The results show that salt-stress (NaCl and concentrated nutrient solution, reduce all the investigated processes in a different degree. NaCl-stress retarded most seriously growth of apical part and blades in contrast to 7-times concentrated nutrient solution decreasing mainly the rate of root and blade growth. Photosynthesis and 14C-translocation of 14C-assimilates were retarded more seriously by NaCl than by 7-times concentrated nutrient. solution. In the case of seriously stressed plants GA3 and cytokinins (more effectively reversed the ,negative effect of stress conditions both on the photosynthesis and on the 14C-tramslocation. On the basis of the obtained results, it seemes that changes in the rate of investigated processes in salinized plants are due to hormonal disturbances which cause directly or indirectly retardation of photosynthesis and trans-location of assimilates.

  18. Toxic Stress: Effects, Prevention and Treatment

    Directory of Open Access Journals (Sweden)

    Hillary A. Franke

    2014-11-01

    Full Text Available Children who experience early life toxic stress are at risk of long-term adverse health effects that may not manifest until adulthood. This article briefly summarizes the findings in recent studies on toxic stress and childhood adversity following the publication of the American Academy of Pediatrics (AAP Policy Report on the effects of toxic stress. A review of toxic stress and its effects is described, including factors of vulnerability, resilience, and the relaxation response. An integrative approach to the prevention and treatment of toxic stress necessitates individual, community and national focus.

  19. [MELATONIN CONCENTRATION IN THE BLOOD OF VITILIGO PATIENTS WITH STRESS IN ANAMNESIS].

    Science.gov (United States)

    Tsiskarishvili, N I; Katsitadze, A; Tsiskarishvili, N V; Tsiskarishvil, Ts; Chitanava, L

    2016-05-01

    In recent years, despite some progress in the study of vitiligo many aspects of pathogenesis and treatment of this dermatosis remain unsolved or are highly controversial. It is believed that progression of disease is associated with a genetic predisposition, autoimmune processes and oxidative stress, but the concrete role of stress on the processes having place in the organism of vitiligo patients so far is not investigated. As we know, epiphysis is the main regulator of adaptation of the individual to the environment. An important product of secretion of the pineal gland is the hormone melatonin - a universal regulator of vital functions and biorhythms of the body. Psychoses, neuroses, depression, immunopathology are aspects of disturbances in circadian, seasonal and annual rhythms of the synthesis of this hormone. Clinical and experimental studies indicate that the hormone melatonin, which is one of the links in a stress defense mechanism of the body, has antioxidant and immunomodulatory properties. The purpose of this study was to determine plasma level of melatonin in the blood of vitiligo patients (with stress in anamnesis), depending on the clinical form and duration of the disease. 41 patients with vitiligo (16 with segmental and 25 with non-segmental form) with stress in anamnesis and duration of disease from several months to 20 years were under observation. The level of melatonin in the blood plasma was determined by ELISA (IBL - international - reagent), the results were expressed in units of pg/ml. According to the results of our study, 8 patients with segmental vitiligo had the normal level of plasma melatonin concentration (in the range of 20.2-31.1 pg/ml), in 2 cases - the level was near the norm (19.2 pg/ml). In the group of patients with non-segmental vitiligo, the level of melatonin was below the norm (12.5 pg/ml) and in 2 cases, the content of melatonin was very low - 4.05 pg / ml. Correlation analysis of melatonin levels with duration of disease

  20. Effect of applied environmental stress on growth, photosynthesis, carbon allocation, and hydrocarbon production in Euphorbia lathyris

    International Nuclear Information System (INIS)

    Taylor, S.E.; Calvin, M.

    1988-01-01

    Photosynthetic activity was reduced by salinity stress, but is was found to be less sensitive than growth. Salinity stress also caused changes in the concentrations of specific cations. Moderate water stress had little effect on growth, but large changes in hydrocarbon production were still observed. Carbon allocation experiments with radiolabeled carbon indicated that carbon for latex production was supplied by nearby leaves, with some translocation down the stem also occurring

  1. The Effect of Vermicompost on Reducing the Adverse Effects of Water Stress on Growth and Chemical Composition of Corn in a Calcareous Soil

    Directory of Open Access Journals (Sweden)

    leila zare

    2017-01-01

    Full Text Available Introduction: Vermicompost is one of the important bio-fertilizer which is the product of the process of composting different organic wastes such as manures and crop residues using different earthworms. Vermicomposts, especially those are derived from animal wastes,contain the large amounts of nutrients compaired with the composts prepared from crop residues. Vermicomposts contain plant available form of nutrients such as nitrate nitrogen, exchangeable phosphorus and potassium, calcium and magnesium. Nowadays, the use of vermicompost in sustainable agriculture to improve the growth and quality of fruits and crops is very common. Drought occurs when the amount of moisture in soil and water resources and rainfall is less than what plants need for normal growth and function. Two thirds of farm lands in Iran have been located in arid and semi-arid regions with annual rainfall less than150 mm that has been distributed irregularly and unpredictable during growth season imposing water stress in most crops. It indicates the importance of water management and proposing different strategies for mitigating detrimental effect of water stress in croplands. Due to the fact that crops nutrient management under drought and water stress using organic fertilizers is an effective method in reaching to high yields in sustainable agriculture, the objective of the present study was to investigate the influence of vermicompost application on reducing the adverse effects of water stress on the growth and chemical composition of corn in a calcareous soil. Materials and Methods: In order to study the influence of water stress and application of vermicompost on corn dry matter yield and nutrients concentration of corn shoot, a greenhouse factorial experiment (4×3 in completely randomized design with three replications was conducted in college of agriculture, Shiraz university, Shiraz, Iran. The factors consisted of four vermicompost levels (0, 10, 20 and30g kg-1soil

  2. Effect of heating rate on caustic stress corrosion cracking

    International Nuclear Information System (INIS)

    Indig, M.E.; Hoffman, N.J.

    1977-01-01

    To evaluate effects of a large water leak into the sodium side of a steam generator in a Liquid Metal Fast Breeder Reactor the Liquid Metal Engineering Center (LMEC) at Canoga Park, California, is performing a series of tests in a Large Leak Test Rig (LLTR). This test series involves heating a large steam generator that possibly contains localized pockets of aqueous caustic retained from a previous sodium-water reaction. Such pockets of caustic solution could be in contact with welds and other components that contain residual stresses up to the yield point. The LMEC and General Electric (GE) ran a series of tests to evaluate the effect of heating rate on caustic stress corrosion cracking (SCC) for alloys either used or considered for the LLTR. A summary of the temperatures and caustic concentration ranges that can result in caustic SCC for carbon steel and Type-304 stainless steel is given

  3. Rheology of dilute acid hydrolyzed corn stover at high solids concentration.

    Science.gov (United States)

    Ehrhardt, M R; Monz, T O; Root, T W; Connelly, R K; Scott, C T; Klingenberg, D J

    2010-02-01

    The rheological properties of acid hydrolyzed corn stover at high solids concentration (20-35 wt.%) were investigated using torque rheometry. These materials are yield stress fluids whose rheological properties can be well represented by the Bingham model. Yield stresses increase with increasing solids concentration and decrease with increasing hydrolysis reaction temperature, acid concentration, and rheometer temperature. Plastic viscosities increase with increasing solids concentration and tend to decrease with increasing reaction temperature and acid concentration. The solids concentration dependence of the yield stress is consistent with that reported for other fibrous systems. The changes in yield stress with reaction conditions are consistent with observed changes in particle size. This study illustrates that torque rheometry can be used effectively to measure rheological properties of concentrated biomass.

  4. Use of an integrated biomarker-based strategy to evaluate physiological stress responses induced by environmental concentrations of caffeine in the Mediterranean mussel Mytilus galloprovincialis.

    Science.gov (United States)

    Capolupo, Marco; Valbonesi, Paola; Kiwan, Alisar; Buratti, Sara; Franzellitti, Silvia; Fabbri, Elena

    2016-09-01

    The occurrence of caffeine (CF), a biologically active drug, has widely been documented in coastal waters, and whether its environmental concentrations do represent a threat for marine organisms is unclear. The present study aimed at assessing sub-lethal effects induced by a 7-day exposure to environmentally relevant concentrations of CF (5, 50 and 500ng/L) in the Mediterranean mussel, Mytilus galloprovincialis. CF in water and mussel tissues, and a battery of biomarkers, including lysosomal parameters of general stress, oxidative stress responses and endpoints of neurological and genetic damages, were evaluated and tested for significance vs controls (pemerging contaminants in marine invertebrates. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Impact of trace metal concentrations on coccolithophore growth and morphology: laboratory simulations of Cretaceous stress

    Science.gov (United States)

    Faucher, Giulia; Hoffmann, Linn; Bach, Lennart T.; Bottini, Cinzia; Erba, Elisabetta; Riebesell, Ulf

    2017-07-01

    The Cretaceous ocean witnessed intervals of profound perturbations such as volcanic input of large amounts of CO2, anoxia, eutrophication and introduction of biologically relevant metals. Some of these extreme events were characterized by size reduction and/or morphological changes of a few calcareous nannofossil species. The correspondence between intervals of high trace metal concentrations and coccolith dwarfism suggests a negative effect of these elements on nannoplankton biocalcification processes in past oceans. In order to test this hypothesis, we explored the potential effect of a mixture of trace metals on growth and morphology of four living coccolithophore species, namely Emiliania huxleyi, Gephyrocapsa oceanica, Pleurochrysis carterae and Coccolithus pelagicus. The phylogenetic history of coccolithophores shows that the selected living species are linked to Mesozoic species showing dwarfism under excess metal concentrations. The trace metals tested were chosen to simulate the environmental stress identified in the geological record and upon known trace metal interactions with living coccolithophore algae.Our laboratory experiments demonstrated that elevated trace metal concentrations, similarly to the fossil record, affect coccolithophore algae size and/or weight. Smaller coccoliths were detected in E. huxleyi and C. pelagicus, while coccoliths of G. oceanica showed a decrease in size only at the highest trace metal concentrations. P. carterae coccolith size was unresponsive to changing trace metal concentrations. These differences among species allow discriminating the most- (P. carterae), intermediate- (E. huxleyi and G. oceanica) and least-tolerant (C. pelagicus) taxa. The fossil record and the experimental results converge on a selective response of coccolithophores to metal availability.These species-specific differences must be considered before morphological features of coccoliths are used to reconstruct paleo-chemical conditions.

  6. Impact of trace metal concentrations on coccolithophore growth and morphology: laboratory simulations of Cretaceous stress

    Directory of Open Access Journals (Sweden)

    G. Faucher

    2017-07-01

    Full Text Available The Cretaceous ocean witnessed intervals of profound perturbations such as volcanic input of large amounts of CO2, anoxia, eutrophication and introduction of biologically relevant metals. Some of these extreme events were characterized by size reduction and/or morphological changes of a few calcareous nannofossil species. The correspondence between intervals of high trace metal concentrations and coccolith dwarfism suggests a negative effect of these elements on nannoplankton biocalcification processes in past oceans. In order to test this hypothesis, we explored the potential effect of a mixture of trace metals on growth and morphology of four living coccolithophore species, namely Emiliania huxleyi, Gephyrocapsa oceanica, Pleurochrysis carterae and Coccolithus pelagicus. The phylogenetic history of coccolithophores shows that the selected living species are linked to Mesozoic species showing dwarfism under excess metal concentrations. The trace metals tested were chosen to simulate the environmental stress identified in the geological record and upon known trace metal interactions with living coccolithophore algae.Our laboratory experiments demonstrated that elevated trace metal concentrations, similarly to the fossil record, affect coccolithophore algae size and/or weight. Smaller coccoliths were detected in E. huxleyi and C. pelagicus, while coccoliths of G. oceanica showed a decrease in size only at the highest trace metal concentrations. P. carterae coccolith size was unresponsive to changing trace metal concentrations. These differences among species allow discriminating the most- (P. carterae, intermediate- (E. huxleyi and G. oceanica and least-tolerant (C. pelagicus taxa. The fossil record and the experimental results converge on a selective response of coccolithophores to metal availability.These species-specific differences must be considered before morphological features of coccoliths are used to reconstruct paleo-chemical conditions.

  7. Effect of Chinese traditional medicine anti-fatigue prescription on the concentration of the serum testosterone and cortisol in male rats under stress of maximum intensive training

    International Nuclear Information System (INIS)

    Dong Ling; Si Xulan

    2008-01-01

    Objective: To study the effect of chinese traditional medicine anti-fatigue prescription on the concentration of the serum testosterone (T) and cortisol (C) in male rats under the stress of maximum intensive training. Methods: Wistar male rat models of stress under maximum intensity training were established (n=40) and half of them were treated with Chinese traditional medicine anti-fatigue prescription twenty undisturbed rats served as controls. Testosterone and cortisol serum levels were determined with RIA at the end of the seven weeks' experiment. Results: Maximum intensive training would cause the level of the serum testosterone lowered, the concentration of the cortisol elevated and the ratio of T/C reduced. The serum T levels and T/C ratio were significantly lower and cortisol levels significantly higher in the untreated models than those in the treated models and controls (P<0.01). The levels of the two hormones were markedly corrected in the treated models with no significantly differences from those in the controls. However, the T/C ratio was still significantly lower than that in the controls (P <0.05) due to a relatively slightly greater degree of reduction of T levels. Conclusion: Anti-fatigue prescription can not only promote the recovery of fatigue after the maximum intensive training but also strengthen the anabolism of the rats. (authors)

  8. Independent Effects of Neighborhood Poverty and Psychosocial Stress on Obesity Over Time.

    Science.gov (United States)

    Kwarteng, Jamila L; Schulz, Amy J; Mentz, Graciela B; Israel, Barbara A; Perkins, Denise White

    2017-12-01

    The objective of the study was to examine the independent effects of neighborhood poverty and psychosocial stress on increases in central adiposity over time. Data are from a community sample of 157 Non-Hispanic Black, Non-Hispanic White, and Hispanic adults collected in 2002-2003 and 2007-2008, and from the 2000 Decennial Census. The dependent variable was waist circumference. Independent variables included neighborhood poverty, perceived neighborhood physical environment, family stress, safety stress, everyday unfair treatment, and a cumulative stress index. Weighted 3-level hierarchical linear regression models for a continuous outcome were used to assess the effects of neighborhood poverty and psychosocial stress on central adiposity over time. We also assessed whether psychosocial stress mediated the association between neighborhood poverty and central adiposity. Neighborhood poverty and everyday unfair treatment at baseline were independently associated with increases in central adiposity over time, accounting for the other indicators of stress. Perceptions of the neighborhood physical environment and cumulative stress mediated associations between neighborhood poverty and central adiposity. Results suggest that residing in neighborhoods with higher concentrations of poverty and exposure to everyday unfair treatment independently heighten risk of increased central adiposity over time. Associations between neighborhood poverty and central adiposity were mediated by perceptions of the neighborhood physical environment and by the cumulative stress index. Public health strategies to reduce obesity should consider neighborhood poverty and exposure to multiple sources of psychosocial stress, including everyday unfair treatment.

  9. Effect of salt hyperosmotic stress on yeast cell viability

    Directory of Open Access Journals (Sweden)

    Logothetis Stelios

    2007-01-01

    Full Text Available During fermentation for ethanol production, yeasts are subjected to different kinds of physico-chemical stresses such as: initially high sugar concentration and low temperature; and later, increased ethanol concentrations. Such conditions trigger a series of biological responses in an effort to maintain cell cycle progress and yeast cell viability. Regarding osmostress, many studies have been focused on transcriptional activation and gene expression in laboratory strains of Saccharomyces cerevisiae. The overall aim of this present work was to further our understanding of wine yeast performance during fermentations under osmotic stress conditions. Specifically, the research work focused on the evaluation of NaCl-induced stress responses of an industrial wine yeast strain S. cerevisiae (VIN 13, particularly with regard to yeast cell growth and viability. The hypothesis was that osmostress conditions energized specific genes to enable yeast cells to survive under stressful conditions. Experiments were designed by pretreating cells with different sodium chloride concentrations (NaCl: 4%, 6% and 10% w/v growing in defined media containing D-glucose and evaluating the impact of this on yeast growth and viability. Subsequent fermentation cycles took place with increasing concentrations of D-glucose (20%, 30%, 40% w/v using salt-adapted cells as inocula. We present evidence that osmostress induced by mild salt pre-treatments resulted in beneficial influences on both cell viability and fermentation performance of an industrial wine yeast strain.

  10. Effects of ACTH, capture, and short term confinement on glucocorticoid concentrations in harlequin ducks (Histrionicus histrionicus)

    Science.gov (United States)

    Nilsson, P.B.; Hollmén, Tuula E.; Atkinson, S.; Mashburn, K.L.; Tuomi, P.A.; Esler, Daniel N.; Mulcahy, D.M.; Rizzolo, D.J.

    2008-01-01

    Little is known about baseline concentrations of adrenal hormones and hormonal responses to stress in sea ducks, although significant population declines documented in several species suggest that sea ducks are exposed to increased levels of environmental stress. Such declines have been observed in geographically distinct harlequin duck populations. We performed an adrenocorticotropic hormone (ACTH) challenge to evaluate adrenal function and characterize corticosterone concentrations in captive harlequin ducks and investigated the effects of capture, surgery, and short term confinement on corticosterone concentrations in wild harlequin ducks. Harlequin ducks responded to the ACTH challenge with an average three-fold increase in serum corticosterone concentration approximately 90 min post injection, and a four- to five-fold increase in fecal glucocorticoid concentration 2 to 4 h post injection. Serum corticosterone concentrations in wild harlequin ducks increased within min of capture and elevated levels were found for several hours post capture, indicating that surgery and confinement maintain elevated corticosterone concentrations in this species. Mean corticosterone concentrations in wild harlequin ducks held in temporary captivity were similar to the maximum response levels during the ACTH challenge in captive birds. However, large variation among individuals was observed in responses of wild birds, and we found additional evidence suggesting that corticosterone responses varied between hatch year and after hatch year birds.

  11. Treatment of β-Thalassemia/Hemoglobin E with Antioxidant Cocktails Results in Decreased Oxidative Stress, Increased Hemoglobin Concentration, and Improvement of the Hypercoagulable State

    Directory of Open Access Journals (Sweden)

    Orn-uma Yanpanitch

    2015-01-01

    Full Text Available Studies on the antioxidant treatment for thalassemia have reported variable outcomes. However, treatment of thalassemia with a combination of hydrophobic and hydrophilic antioxidants and an iron chelator has not been studied. This study investigated the effects of antioxidant cocktails for the treatment of β-thalassemia/hemoglobin E (HbE, which is the most common form of β-thalassemia in Southeast Asia. Sixty patients were divided into two groups receiving N-acetylcysteine, deferiprone, and either curcuminoids (CUR or vitamin E (Vit-E, and their hematological parameters, iron load, oxidative stress, and blood coagulation potential were evaluated. Patients were classified as responders if they showed the improvements of the markers of iron load and oxidative stress, otherwise as nonresponders. During treatment, the responders in both groups had significantly decreased iron load, oxidative stress, and coagulation potential and significantly increased antioxidant capacity and hemoglobin concentration. The significantly maximum increase (P<0.01 in hemoglobin concentration was 11% at month 4 in CUR group responders and 10% at month 10 in Vit-E group responders. In conclusion, the two antioxidant cocktails can improve anemia, iron overload, oxidative stress, and hypercoagulable state in β-thalassemia/HbE.

  12. Effect of silicon application on physiological characteristics and growth of wheat (Triticum aestivum L. under drought stress condition

    Directory of Open Access Journals (Sweden)

    A. Karmollachaab

    2016-05-01

    Full Text Available In order to investigate the effect of silicon application on some physiological characteristics and growth of Wheat (Triticum aestivum L. under late drought stress condition, an experiment was conducted at the Agriculture and Natural Resources University of Ramin, Khuzestan during year 2012. The experiment was conducted in the open environment as factorial randomized complete block design with three levels of drought stress (irrigation after 25, 50 and 75% depletion of available water content as the first factor and four levels of silicon (0, 10, 20 and 30 mg Si.kg-1 soil as the second factor with three replications. The results showed that drought stress imposed a negative significant effect on all traits. The drought stress led to increased electrolyte leakage and proline content, cuticular wax, leaf silicon concentration, superoxide dismutase activity (SOD and grain potassium were decreased. The severe drought stress has most effect on electrolyte leakage (up to 53%. The application of silicon except the shoot/root parameter, on all characters have been affected so that application of 30 mg Si.kg-1 soil led to decrease electrolyte leakage up to 22.5% and increased SOD activity, proline content, cuticular wax grain K and flag leaf Si concentration, 25, 12.8, 21, 17 and 30% compared to control, respectively. In general, the results showed a positive effect of silicon on wheat plant under stress conditions that were higher than no stress condition.

  13. Investigation of the effect of biologically active threo-Ds-isocitric acid on oxidative stress in Paramecium caudatum.

    Science.gov (United States)

    Morgunov, Igor G; Karpukhina, Olga V; Kamzolova, Svetlana V; Samoilenko, Vladimir A; Inozemtsev, Anatoly N

    2018-01-02

    The effect of biologically active form (threo-Ds-) of isocitric acid (ICA) on oxidative stress was studied using the infusorian Paramecium caudatum stressed by hydrogen peroxide and salts of some heavy metals (Cu, Pb, Zn, and Cd). ICA at concentrations between 0.5 and 10 mM favorably influenced the infusorian cells with oxidative stress induced by the toxicants studied. The maximal antioxidant effect of ICA was observed at its concentration 10 mM irrespective of the toxicant used (either H 2 O 2 or heavy metal ions). ICA was found to be a more active antioxidant than ascorbic acid. Biologically active pharmaceutically pure threo-Ds-ICA was produced through cultivation of the yeast Yarrowia lipolytica and isolated from the culture liquid in the form of crystalline monopotassium salt with a purity of 99.9%.

  14. Effect of silica Nanoparticles on Basil (Ocimum basilicum Under Salinity Stress

    Directory of Open Access Journals (Sweden)

    Manizheh Kalteh

    2014-08-01

    Full Text Available Application of nanofertilizers is one of the promising methods for increasing resources use efficiency and reducing environmental pollutions. Uncontrolled application of chemical fertilizer and pesticides has caused many problems to human health and domestic animals. Nanofertilizers application could be a suitable way to reduce these problems. Accordingly, in order to assess the silicon nanoparticles effect on some vegetative features of basil under salinity stress, a factorial experiment based on a completely randomized design with three replications was conducted in greenhouse condition. Treatments included different levels of silicon fertilizer (without silicon, normal silicon fertilizer and silicon nanoparticles and salinity stress (1, 3 and 6 ds/m. Physiological traits (chlorophyll and proline content of leaves and morphological traits (shoot fresh weight and dry weight were investigated in this study. Results showed a significant reduction in growth and development indices due to the salinity stress.  Leaf dry and fresh weight reduced by increment in NaCl concentration while significantly (P≤0.01 increased with silicon nanoparticles application. The chlorophyll content reduced in salinity stress, but increased by silicon nanoparticles treatment. Proline content increased under salinity stress which was a response to stress. Moreover, proline increased by silicon nanoparticles which was due to tolerance induction in plant. Silicon nanoparticles application reduced the pollution effects originated from salinity in Basil.

  15. Effect of saline stress on plasma membrane structure and function of barley roots

    International Nuclear Information System (INIS)

    Rahmani, F. H.

    2000-01-01

    Barely (Hordeum vulgare L. c v. Black Local) plants were grown hydroponic ally under different saline stresses (50, 100, 150 And 200 mm NaCI. The adverse effect of each saline stress on the structure and function of root cells plasma membrane was studied in terms of root surface ATPase activation by NaCI in the reaction mixture. Was 0, 50, 100. 150 and 200mM. ATPase activity was found to be increased gradually at certain concentrations of NaCI. For control and 50mM stressed plants, the increase in root surface ATPase activity was started at 150mM NaCI. For 100mM stressed plants it was started at 100mM NaCI. For 150 and 200mM stressed plants it was stated at 50mM NaCI Results indicated that the adverse effect of the growth medium saline stresses on the integrity of the plasma membrane was started at 100mM saline stress. Accordingly the role of plasma membrane bound ATPase in active ion transport was disturbed at 100mM saline stress and may be impaired at 150 and 200mM saline stresses. It was suggested that the lipid environment of the plasma membrane surrounding ATPase was modified by the saline stresses 100-200mM. (author). 38 refs., 2 figs., 2 tabs

  16. Effects of thermal residual stresses and fiber packing on deformation of metal-matrix composites

    International Nuclear Information System (INIS)

    Nakamura, T.; Suresh, S.

    1993-01-01

    The combined effects of thermal residual stresses and fiber spatial distribution on the deformation of a 6061 aluminum alloy containing a fixed concentration unidirectional boron fibers have been analyzed using detailed finite element models. The geometrical structure includes perfectly periodic, uniformly space fiber arrangements in square and hexagonal cells, as well as different cells in which either 30 or 60 fibers are randomly placed in the ductile matrix. The model involves an elastic-plastic matrix, elastic fibers, and mechanically bonded interfaces. The results indicate that both fiber packing and thermal residual stresses can have a significant effect on the stress-strain characteristics of the composite. The thermal residual stresses cause pronounced matrix yielding which also influences the apparent overall stiffness of the composite during the initial stages of subsequent far-field loading along the axial and transverse direction. Furthermore, the thermal residual stresses apparently elevate the flow stress of the composite during transverse tension. Such effects can be traced back to the level of constraint imposed on the matrix by local fiber spacing. The implications of the present results to the processing of the composites are also briefly addressed

  17. Relationships between soluble sugar concentrations in roots and ecosystem stress for first-year sugar maple seedlings

    Energy Technology Data Exchange (ETDEWEB)

    McLaughlin, J.W.; Reed, D.D.; Jurgensen, M.F.; Mroz, G.D.; Bagley, S.T. [Michigan Technological University, Houghton, MI (United States). School of Forestry and Wood Products

    1996-03-01

    Accumulation of reducing sugars (i.e. glucose and fructose) in plant roots has been consistently correlated with forest dieback and decline and, therefore, has potential as a biological indicator of ecosystem stress. In this study, the relationships between acidic deposition and `natural` (temperature, mycorrhizae, and nutrition) factors with first-year sugar maple seedling root sugar concentrations and growth were assessed in two sugar maple dominated forests in Michigan. Seedlings at the southern site (Wellston) had greater root growth, phosphorus, total sugar, and sucrose concentrations in roots, but lower reducing sugar concentration in roots. In addition, percent root length colonized by vesicular-arbuscular mycorrhizal fungi was less than that found for seedlings growing at the northern site (Alberta). Throughfall deposition of nitrate, sulfate, and hydrogen ions was not significantly correlated with seedling total or reducing sugar concentration. Total sugar concentration in seedling roots was positively correlated with air and soil temperatures at the southern site, but not at the northern site. Seedling tissue phosphorus concentration was correlated with total sugars at both sites, with sucrose at the southern site, and reducing sugars at the northern site. Mycorrhizal colonization rates at the Alberta site were positively correlated with reducing sugar concentration in seedling roots and negatively correlated with sucrose concentration. The results suggest that differences in seedling root sugar concentrations in these two forests are related to seedling root growth and are most likely due to ecological variables, such as available soil phosphorus, temperature, and growing season length through some complex interaction with mycorrhizae rather than acidic deposition stress. 56 refs., 3 figs.

  18. Stress-induced endocrine response and anxiety: the effects of comfort food in rats.

    Science.gov (United States)

    Ortolani, Daniela; Garcia, Márcia Carvalho; Melo-Thomas, Liana; Spadari-Bratfisch, Regina Celia

    2014-05-01

    The long-term effects of comfort food in an anxiogenic model of stress have yet to be analyzed. Here, we evaluated behavioral, endocrine and metabolic parameters in rats submitted or not to chronic unpredictable mild stress (CUMS), with access to commercial chow alone or to commercial chow and comfort food. Stress did not alter the preference for comfort food but decreased food intake. In the elevated plus-maze (EPM) test, stressed rats were less likely to enter/remain in the open arms, as well as being more likely to enter/remain in the closed arms, than were control rats, both conditions being more pronounced in the rats given access to comfort food. In the open field test, stress decreased the time spent in the centre, independent of diet; neither stress nor diet affected the number of crossing, rearing or grooming episodes. The stress-induced increase in serum corticosterone was attenuated in rats given access to comfort food. Serum concentration of triglycerides were unaffected by stress or diet, although access to comfort food increased total cholesterol and glucose. It is concluded that CUMS has an anorexigenic effect. Chronic stress and comfort food ingestion induced an anxiogenic profile although comfort food attenuated the endocrine stress response. The present data indicate that the combination of stress and access to comfort food, common aspects of modern life, may constitute a link among stress, feeding behavior and anxiety.

  19. Fluvoxamine maleate effects on dopamine signaling in the prefrontal cortex of stressed Parkinsonian rats: Implications for learning and memory.

    Science.gov (United States)

    Dallé, Ernest; Daniels, Willie M U; Mabandla, Musa V

    2017-06-01

    Parkinson's disease (PD) is also associated with cognitive impairment and reduced extrinsic supply of dopamine (DA) to the prefrontal cortex (PFC). In the present study, we looked at whether exposure to early life stress reduces DA and serotonin (5-HT) concentration in the PFC thus leading to enhanced cognitive impairment in a Parkinsonian rat model. Maternal separation was the stressor used to develop an animal model for early life stress that has chronic effects on brain and behavior. Sprague-Dawley rats were treated with the antidepressant Fluvoxamine maleate (FM) prior to a unilateral 6-hydroxydopamine (6-OHDA) lesion to model motor deficits in rats. The Morris water maze (MWM) and the forelimb use asymmetry (cylinder) tests were used to assess learning and memory impairment and motor deficits respectively. Blood plasma was used to measure corticosterone concentration and prefrontal tissue was collected for lipid peroxidation, DA, and 5-HT analysis. Our results show that animals exposed to early life stress displayed learning and memory impairment as well as elevated basal plasma corticosterone concentration which were attenuated by treatment with FM. A 6-OHDA lesion effect was evidenced by impairment in the cylinder test as well as decreased DA and 5-HT concentration in the PFC. These effects were attenuated by FM treatment resulting in higher DA concentration in the PFC of treated animals than in non-treated animals. This study suggests that DA and 5-HT signaling in the PFC are responsive to FM and may reduce stress-induced cognitive impairment in PD. Copyright © 2017. Published by Elsevier Inc.

  20. Effects of advanced laser processing on the microstructure and residual stresses of H13 tool steel

    OpenAIRE

    Trojan, Karel; Ocelík, Václav; Ganev, Nikolaj; Němeček, Stanislav; Čapek, Jiří

    2017-01-01

    The aim of this paper is to describe the effects of laser processing on the microstructure and residual stresses of laser cladded H13 tool steel on the classical construct steel S355 substrate. This research paper concludes that in this case of laser cladding, phase transformation and not shrinkage is likely to be a dominant effect on the formation of compressive residual stresses along the clad. Furthermore, martensitic structure and unequal concentration of alloying elements was observed on...

  1. Stress Effects on Multiple Memory System Interactions

    Science.gov (United States)

    Ness, Deborah; Calabrese, Pasquale

    2016-01-01

    Extensive behavioural, pharmacological, and neurological research reports stress effects on mammalian memory processes. While stress effects on memory quantity have been known for decades, the influence of stress on multiple memory systems and their distinct contributions to the learning process have only recently been described. In this paper, after summarizing the fundamental biological aspects of stress/emotional arousal and recapitulating functionally and anatomically distinct memory systems, we review recent animal and human studies exploring the effects of stress on multiple memory systems. Apart from discussing the interaction between distinct memory systems in stressful situations, we will also outline the fundamental role of the amygdala in mediating such stress effects. Additionally, based on the methods applied in the herein discussed studies, we will discuss how memory translates into behaviour. PMID:27034845

  2. Stress Effects on Multiple Memory System Interactions.

    Science.gov (United States)

    Ness, Deborah; Calabrese, Pasquale

    2016-01-01

    Extensive behavioural, pharmacological, and neurological research reports stress effects on mammalian memory processes. While stress effects on memory quantity have been known for decades, the influence of stress on multiple memory systems and their distinct contributions to the learning process have only recently been described. In this paper, after summarizing the fundamental biological aspects of stress/emotional arousal and recapitulating functionally and anatomically distinct memory systems, we review recent animal and human studies exploring the effects of stress on multiple memory systems. Apart from discussing the interaction between distinct memory systems in stressful situations, we will also outline the fundamental role of the amygdala in mediating such stress effects. Additionally, based on the methods applied in the herein discussed studies, we will discuss how memory translates into behaviour.

  3. Stress Effects on Multiple Memory System Interactions

    Directory of Open Access Journals (Sweden)

    Deborah Ness

    2016-01-01

    Full Text Available Extensive behavioural, pharmacological, and neurological research reports stress effects on mammalian memory processes. While stress effects on memory quantity have been known for decades, the influence of stress on multiple memory systems and their distinct contributions to the learning process have only recently been described. In this paper, after summarizing the fundamental biological aspects of stress/emotional arousal and recapitulating functionally and anatomically distinct memory systems, we review recent animal and human studies exploring the effects of stress on multiple memory systems. Apart from discussing the interaction between distinct memory systems in stressful situations, we will also outline the fundamental role of the amygdala in mediating such stress effects. Additionally, based on the methods applied in the herein discussed studies, we will discuss how memory translates into behaviour.

  4. Effective stress coefficient for uniaxial strain condition

    DEFF Research Database (Denmark)

    Alam, M.M.; Fabricius, I.L.

    2012-01-01

    one dimensional rock mechanical deformation. We further investigated the effect of boundary condition on the stress dependency of effective stress coefficient and discussed its application in reservoir study. As stress field in the reservoirs are most unlikely to be hydrostatic, effective stress...... determined under uniaxial strain condition will be more relevant in reservoir studies. Copyright 2012 ARMA, American Rock Mechanics Association....

  5. Effect of graphene oxide on copper stress in Lemna minor L.: evaluating growth, biochemical responses, and nutrient uptake.

    Science.gov (United States)

    Hu, Changwei; Liu, Lei; Li, Xiuling; Xu, Yundi; Ge, Zhigang; Zhao, Yongjun

    2018-01-05

    The wide application and unique properties of graphene oxide (GO) make it to interact with other pollutants and subsequently alter their behavior and toxicity. We evaluated the influences of GO at different concentrations (1 and 5mg/L) on copper (Cu) stress in duckweed (Lemna minor L.) GO below a concentration of 5mg/L showed no adverse effects on L. minor. The addition of Cu above 10μM represented a stress condition, which was evidenced by various parameters such as frond number, percent inhibition of growth rate (I r ), total chlorophyll content, dry weight, superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). When L. minor was simultaneously exposed to GO and Cu, especially at a GO concentration of 5mg/L and a Cu level above 10μM, the increase of I r and decrease of chlorophyll content were inhibited, suggesting that the Cu stress was diminished in the presence of GO. The addition of Cu alone, ranging between 5 and 20μM, increased Cu, B, Mn, Fe, Co, and Zn uptake, but decreased P uptake. Our results suggest that GO can lessen Cu stress in L. minor via Cu adsorption, thereby protecting the plants from the damaging effects of high Cu concentrations. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Neighborhood disadvantage and adolescent stress reactivity

    Directory of Open Access Journals (Sweden)

    Daniel A. Hackman

    2012-10-01

    Full Text Available Lower socioeconomic status (SES is associated with higher levels of life stress, which in turn affect stress physiology. SES is related to basal cortisol and diurnal change, but it is not clear if SES is associated with cortisol reactivity to stress. To address this question, we examined the relationship between two indices of SES, parental education and concentrated neighborhood disadvantage, and the cortisol reactivity of African-American adolescents to a modified version of the Trier Social Stress Test. We found that concentrated disadvantage was associated with cortisol reactivity and this relationship was moderated by gender, such that higher concentrated disadvantage predicted higher cortisol reactivity and steeper recovery in boys but not in girls. Parental education, alone or as moderated by gender, did not predict reactivity or recovery, while neither education nor concentrated disadvantage predicted estimates of baseline cortisol. This finding is consistent with animal literature showing differential vulnerability, by gender, to the effects of adverse early experience on stress regulation and the differential effects of neighborhood disadvantage in adolescent males and females. This suggests that the mechanisms underlying SES differences in brain development and particularly reactivity to environmental stressors may vary across genders.

  7. Red blood cells sensitivity to oxidative stress in the presence of low concentrations of uranium compound

    Energy Technology Data Exchange (ETDEWEB)

    Shevchenko, O.G. [Institute of Biology, Komi Scientific Centre, Ural Branch of Russian Academy of Sciences, 167982, Syktyvkar (Russian Federation)

    2014-07-01

    Uranium is a natural radioactive element widespread in biosphere. There are a few works that examined cellular and molecular mechanisms of uranium toxicity. Red blood cells are classical model to investigate toxicity mechanisms on cell membrane system. The aim of present work is to study the effect of uranyl ion in nano-molar concentrations on erythrocytes sensitivity (in vitro) to factors provoking acute oxidative stress. Uranyl ions were added to suspension of mice red blood cells in PBS as UO{sub 2}Cl{sub 2} solution. Samples were incubated in a thermostatic shaker at 37 deg. C during 3-5 hours. Than acute oxidative stress was induced by H{sub 2}O{sub 2} (0.9 mM) or AAPH (5 mM) solutions. Destabilization of the membrane was induced by nonionic detergent Triton X-100. The hemolysis degree and the content of LPO secondary products reacting with 2-thiobarbituric acid in the incubation mixture were determined spectrophotometrically. The ratio of hemoglobin various forms (oxyHb, metHb and ferrylHb) was calculated taking into account extinction coefficients. It was shown that uranyl chloride enhances cell sensitivity to nonionic detergent Triton X-100 effects, indicating alterations of membrane acyl chain order due to contact with the radionuclide ions. Uranium exposure also caused an increase in the cell sensitivity to the AAPH effects, resulted in a decrease in red cell survival rate, a sharp increase in accumulation of hemoglobin oxidation products and a slight increase in the concentration of LPO secondary products. Thus, uranyl ions change physicochemical properties of the erythrocyte membranes that resulted in increased sensitivity to effects of peroxyl radicals formed by thermal decomposition of AAPH. On the contrary, use of another source of free radicals - H{sub 2}O{sub 2} - after uranyl ions exposure resulted in marked decrease of oxidative hemolysis, inhibition of LPO and hemoglobin oxidation. Since the uranium chemical properties similar to properties of

  8. Analysis of the Effects of Cell Stress and Cytotoxicity on In ...

    Science.gov (United States)

    Chemical toxicity can arise from disruption of specific biomolecular functions or through more generalized cell stress and cytotoxicity-mediated processes. Here, concentration-dependent responses of 1063 chemicals including pharmaceuticals, natural products, pesticidals, consumer, and industrial chemicals across a diverse battery of 821 in vitro assay endpoints from 7 high-throughput assay technology platforms were analyzed in order to better distinguish between these types of activities. Both cell-based and cell-free assays showed a rapid increase in the frequency of responses at concentrations where cell stress / cytotoxicity responses were observed in cell-based assays. Chemicals that were positive on at least two viability/cytotoxicity assays within the concentration range tested (typically up to 100 M) activated a median of 12% of assay endpoints while those that were not cytotoxic in this concentration range activated 1.3% of the assays endpoints. The results suggest that activity can be broadly divided into: (1) specific biomolecular interactions against one or more targets (e.g., receptors or enzymes) at concentrations below which overt cytotoxicity-associated activity is observed; and (2) activity associated with cell stress or cytotoxicity, which may result from triggering of specific cell stress pathways, chemical reactivity, physico-chemical disruption of proteins or membranes, or broad low-affinity non-covalent interactions. Chemicals showing a g

  9. Effect of aspartic acid and glutamate on metabolism and acid stress resistance of Acetobacter pasteurianus.

    Science.gov (United States)

    Yin, Haisong; Zhang, Renkuan; Xia, Menglei; Bai, Xiaolei; Mou, Jun; Zheng, Yu; Wang, Min

    2017-06-15

    Acetic acid bacteria (AAB) are widely applied in food, bioengineering and medicine fields. However, the acid stress at low pH conditions limits acetic acid fermentation efficiency and high concentration of vinegar production with AAB. Therefore, how to enhance resistance ability of the AAB remains as the major challenge. Amino acids play an important role in cell growth and cell survival under severe environment. However, until now the effects of amino acids on acetic fermentation and acid stress resistance of AAB have not been fully studied. In the present work the effects of amino acids on metabolism and acid stress resistance of Acetobacter pasteurianus were investigated. Cell growth, culturable cell counts, acetic acid production, acetic acid production rate and specific production rate of acetic acid of A. pasteurianus revealed an increase of 1.04, 5.43, 1.45, 3.30 and 0.79-folds by adding aspartic acid (Asp), and cell growth, culturable cell counts, acetic acid production and acetic acid production rate revealed an increase of 0.51, 0.72, 0.60 and 0.94-folds by adding glutamate (Glu), respectively. For a fully understanding of the biological mechanism, proteomic technology was carried out. The results showed that the strengthening mechanism mainly came from the following four aspects: (1) Enhancing the generation of pentose phosphates and NADPH for the synthesis of nucleic acid, fatty acids and glutathione (GSH) throughout pentose phosphate pathway. And GSH could protect bacteria from low pH, halide, oxidative stress and osmotic stress by maintaining the viability of cells through intracellular redox equilibrium; (2) Reinforcing deamination of amino acids to increase intracellular ammonia concentration to maintain stability of intracellular pH; (3) Enhancing nucleic acid synthesis and reparation of impaired DNA caused by acid stress damage; (4) Promoting unsaturated fatty acids synthesis and lipid transport, which resulted in the improvement of cytomembrane

  10. Most oxidative stress response in water samples comes from unknown chemicals: the need for effect-based water quality trigger values.

    Science.gov (United States)

    Escher, Beate I; van Daele, Charlotte; Dutt, Mriga; Tang, Janet Y M; Altenburger, Rolf

    2013-07-02

    The induction of adaptive stress response pathways is an early and sensitive indicator of the presence of chemical and non-chemical stressors in cells. An important stress response is the Nrf-2 mediated oxidative stress response pathway where electrophilic chemicals or chemicals that cause the formation of reactive oxygen species initiate the production of antioxidants and metabolic detoxification enzymes. The AREc32 cell line is sensitive to chemicals inducing oxidative stress and has been previously applied for water quality monitoring of organic micropollutants and disinfection byproducts. Here we propose an algorithm for the derivation of effect-based water quality trigger values for this end point that is based on the combined effects of mixtures of regulated chemicals. Mixture experiments agreed with predictions by the mixture toxicity concept of concentration addition. The responses in the AREc32 and the concentrations of 269 individual chemicals were quantified in nine environmental samples, ranging from treated effluent, recycled water, stormwater to drinking water. The effects of the detected chemicals could explain less than 0.1% of the observed induction of the oxidative stress response in the sample, affirming the need to use effect-based trigger values that account for all chemicals present.

  11. Effect of Taper on Stress Distribution of All Ceramic Fixed Partial Dentures: a 3D-FEA Study

    Directory of Open Access Journals (Sweden)

    F. Gerami-Panah

    2005-09-01

    Full Text Available Statement of Problem: Mechanical failure of ceramic materials is controlled by brittle fracture, mostly occurred in tension. In 3-unit all-ceramic FPDs the connector area is considered to be at fracture risk because of tensile stress concentrations.Purpose: The aim of this FE analysis was to evaluate the effect of taper on stress distribution in all-ceramic FPDs.Materials and Methods: In this experimental study two 3-D finite element models of thee-unit IPS-Empress 2 FPDs replacing mandible second premolar were created by means of finite element software. The digital images were obtained from CT scan of human skull. Abutment was reduced with 12 and 22 degrees of taper. The cement layer,PDL, cancellous bone and cortical bone were also modeled. Frameworks of core material were fabricated. A static load of 100 N was applied at mid pontic area.Resolved stresses were calculated according to the Von Mises criterion and principal stresses.Results: In both models stresses were concentrated at the connectors. The maximum stresses were lower in the model with larger taper. The maximum Von Mises stress was recorded at the connector region of the premolar and the pontic. In model with larger taper the patterns of stresses were also more distributed and less concentrated.Conclusion: The highest Von Mises and principal stress were recorded at the connectors. Tensile stresses developed at the gingival connector of premolar and pontic was higher than molar. The stress level in model with 22-degree taper was lower compare to 12-degree and the stress pattern was more distributed, lowered the risk ofconcentrations.

  12. Effects of high salinity from desalination brine on growth, photosynthesis, water relations and osmolyte concentrations of seagrass Posidonia australis

    International Nuclear Information System (INIS)

    Cambridge, M L; Zavala-Perez, A; Cawthray, G R; Mondon, J; Kendrick, G A

    2017-01-01

    Highly saline brines from desalination plants expose seagrass communities to salt stress. We examined effects of raised salinity (46 and 54 psu) compared with seawater controls (37 psu) over 6 weeks on the seagrass, Posidonia australis, growing in tanks with the aim of separating effects of salinity from other potentially deleterious components of brine and determining appropriate bioindicators. Plants survived exposures of 2–4 weeks at 54 psu, the maximum salinity of brine released from a nearby desalination plant. Salinity significantly reduced maximum quantum yield of PSII (chlorophyll a fluorescence emissions). Leaf water potential (Ψ w ) and osmotic potential (Ψ π ) were more negative at increased salinity, while turgor pressure (Ψ p ) was unaffected. Leaf concentrations of K + and Ca 2+ decreased, whereas concentrations of sugars (mainly sucrose) and amino acids increased. We recommend leaf osmolarity, ion, sugar and amino acid concentrations as bioindicators for salinity effects, associated with brine released in desalination plant outfalls. - Highlights: • We separated salt effects of desalination brine from other deleterious components. • Sublethal salinity stress depended on both salinity increase and exposure time. • Very effective osmoregulation led to tolerance of short intervals of high salinity.

  13. Effect of temperature and ionic impurities at very low concentrations on stress corrosion cracking of type 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Ruther, W.E.; Soppet, W.K.; Kassner, T.F.

    1984-11-01

    The relative effect of approx. 12 anion species, in conjunction with hydrogen and sodium cations, on the stress-corrosion-cracking (SCC) behavior of lightly sensitized Type 304 stainless steel was investigated in constant-extension-rate-tensile (CERT) tests at 289/sup 0/C in water with 0.2 ppM dissolved oxygen at total conductivity values of less than or equal to 1 ..mu..S/cm. The results show that the sulfur species, either in acid or sodium form, produce the highest degree of IGSCC relative to other anions. The effect of temperature on the SCC behavior of the material was investigated in CERT tests over the range 110 to 320/sup 0/C in high-purity water and in water containing 0.1 and 1.0 ppM sulfate as H/sub 2/SO/sub 4/ at a dissolved oxygen concentration of 0.2 ppM. The CERT parameters were correlated with impurity concentration (i.e., conductivity) and the electrochemical potential of platinum and Type 304 stainless steel electrodes in the high-temperature environments. Maximum IGSCC occurred at temperatures between approx. 200 and 250/sup 0/C in high-purity water, and the addition of sulfate increased the average crack growth rates and the temperature range over which maximum susceptibility occurred. A distinct transition from intergranular to transgranular and ultimately to a ductile failure mode was observed as the temperature increased from approx. 270 to 320/sup 0/C in high-purity water. This transition was attributed to a decrease in the open-circuit corrosion potential of the steel below a critical value of approx. 0 mV(SHE) at the higher temperature. A large decrease in the crack growth rates of fracture-mechanics-type specimens of the steel was also found when the temperature was increased from 289 to 320/sup 0/C in high-purity water with 0.2 ppM dissolved oxygen. 26 references, 8 figures, 6 tables.

  14. Effect of temperature and ionic impurities at very low concentrations on stress corrosion cracking of type 304 stainless steel

    International Nuclear Information System (INIS)

    Ruther, W.E.; Soppet, W.K.; Kassner, T.F.

    1984-11-01

    The relative effect of approx. 12 anion species, in conjunction with hydrogen and sodium cations, on the stress-corrosion-cracking (SCC) behavior of lightly sensitized Type 304 stainless steel was investigated in constant-extension-rate-tensile (CERT) tests at 289 0 C in water with 0.2 ppM dissolved oxygen at total conductivity values of less than or equal to 1 μS/cm. The results show that the sulfur species, either in acid or sodium form, produce the highest degree of IGSCC relative to other anions. The effect of temperature on the SCC behavior of the material was investigated in CERT tests over the range 110 to 320 0 C in high-purity water and in water containing 0.1 and 1.0 ppM sulfate as H 2 SO 4 at a dissolved oxygen concentration of 0.2 ppM. The CERT parameters were correlated with impurity concentration (i.e., conductivity) and the electrochemical potential of platinum and Type 304 stainless steel electrodes in the high-temperature environments. Maximum IGSCC occurred at temperatures between approx. 200 and 250 0 C in high-purity water, and the addition of sulfate increased the average crack growth rates and the temperature range over which maximum susceptibility occurred. A distinct transition from intergranular to transgranular and ultimately to a ductile failure mode was observed as the temperature increased from approx. 270 to 320 0 C in high-purity water. This transition was attributed to a decrease in the open-circuit corrosion potential of the steel below a critical value of approx. 0 mV(SHE) at the higher temperature. A large decrease in the crack growth rates of fracture-mechanics-type specimens of the steel was also found when the temperature was increased from 289 to 320 0 C in high-purity water with 0.2 ppM dissolved oxygen. 26 references, 8 figures, 6 tables

  15. [Study on physiological characteristics and effects of salt stress in Andrographis paniculata].

    Science.gov (United States)

    Chen, Juan; Gu, Wei; Duan, Jin-Ao; Su, Shu-Lan; Shao, Jing; Geng, Chao

    2014-08-01

    To study the physiological characteristics and effects of salt stress in Andrographis paniculata. Andrographis paniculata was treated with NaCl of different concentration. The photosynthetic characteristics and transpiration rate were an- alyzed by LI-6400 Portable Photosynthesis System. The activities of enzymes were studied with kits. The net photosynthetic rate (Pn) and stomatal conductance (Gs) showed a diurnal variation of bimodal curve, the transpiration rate (Tr) and stomatal limitation (Ls) both had a single peak diurnal variation, while the intercellular CO2 concentration (Ci) and the water use efficiency (WUE) presented a single valley type of diurnal variation. With salt concentration rising, Pn, Tr, Ci, Ca and WUE decreased but L, increased, the activities of SOD, CAT and POD increased firstly and then decreased, while the MDA and proline content showed a rising trend. Andrographis paniculata is a type of sun plant. The net photosynthetic rate of Andrographis paniculata leaves has an obvious "midday depression" phenomenon. The results also indicate that Andrographis paniculata has a resistance to salt stress and appropriate shade is good for the quality improvement.

  16. Effects of magnetized walls on the particle structure and the yield stress of magnetorheological fluids

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Jianfeng, E-mail: zhoujianfeng@njtech.edu.cn [School of Mechanical and Power Engineering, Nanjing Tech University, Nanjing 211816, Jiangsu (China); Mo, Jingwen [Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Shao, Chunlei [School of Mechanical and Power Engineering, Nanjing Tech University, Nanjing 211816, Jiangsu (China); Li, Zhigang [Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

    2015-09-01

    In this work, we investigate the quasi-static shear deformation of magnetic particles (MPs) in a Couette flow of magnetorheological (MR) fluids through Stokesian dynamic simulations. The magnetized walls are modeled by a congregation of magnetic dipoles and their effects on the MPs are considered. The simple shear flow of the base fluid with linear velocity distribution is used to generate the shear deformation of the MP structure and the yield stresses under different shear rates are obtained. Comparing with the relatively long chains forming in base fluid without the effect of magnetized walls, the initial structure of MPs is mainly in the form of short chains due to the attractive force of walls. At the beginning of the shear deformation of the MP structure, the concentration of MPs near the walls is found. As the shear deformation develops, however, the chains concentrate at the center of the simulation domain and the MPs near wall boundaries are attracted to the center. The yield stress depends on the initial structure of MPs which is affected by the magnetized walls. It is revealed that the larger shear rate of base fluid results in the larger yield stress, and the effects of the magnetization intensity of the walls and their space distance on the yield stress are also investigated. - Highlights: • We model a Couette flow of magnetorheological fluid considering magnetized walls. • The walls are modeled by a congregation of magnetic dipoles. • Initial structure of MPs is remarkably affected by the walls, so is yield stress. • Larger base fluid shear rate causes the larger shear deformation and larger yield stress.

  17. Effects of magnetized walls on the particle structure and the yield stress of magnetorheological fluids

    International Nuclear Information System (INIS)

    Zhou, Jianfeng; Mo, Jingwen; Shao, Chunlei; Li, Zhigang

    2015-01-01

    In this work, we investigate the quasi-static shear deformation of magnetic particles (MPs) in a Couette flow of magnetorheological (MR) fluids through Stokesian dynamic simulations. The magnetized walls are modeled by a congregation of magnetic dipoles and their effects on the MPs are considered. The simple shear flow of the base fluid with linear velocity distribution is used to generate the shear deformation of the MP structure and the yield stresses under different shear rates are obtained. Comparing with the relatively long chains forming in base fluid without the effect of magnetized walls, the initial structure of MPs is mainly in the form of short chains due to the attractive force of walls. At the beginning of the shear deformation of the MP structure, the concentration of MPs near the walls is found. As the shear deformation develops, however, the chains concentrate at the center of the simulation domain and the MPs near wall boundaries are attracted to the center. The yield stress depends on the initial structure of MPs which is affected by the magnetized walls. It is revealed that the larger shear rate of base fluid results in the larger yield stress, and the effects of the magnetization intensity of the walls and their space distance on the yield stress are also investigated. - Highlights: • We model a Couette flow of magnetorheological fluid considering magnetized walls. • The walls are modeled by a congregation of magnetic dipoles. • Initial structure of MPs is remarkably affected by the walls, so is yield stress. • Larger base fluid shear rate causes the larger shear deformation and larger yield stress

  18. Cognitive control moderates parenting stress effects on children's diurnal cortisol

    OpenAIRE

    Raffington, Laurel; Schmiedek, Florian; Heim, Christine; Shing, Yee Lee

    2018-01-01

    This study investigated associations between parenting stress in parents and self-reported stress in children with children's diurnal cortisol secretion and whether these associations are moderated by known stress-regulating capacities, namely child cognitive control. Salivary cortisol concentrations were assessed from awakening to evening on two weekend days from 53 6-to-7-year-old children. Children completed a cognitive control task and a self-report stress questionnaire with an experiment...

  19. Stress Concentration in the Bulk Cr2O3: Effects of Temperature and Point Defects

    Directory of Open Access Journals (Sweden)

    Mazharul M. Islam

    2017-01-01

    Full Text Available Modeling the growth and failure of passive oxide films formed on stainless steels is of general interest for the use of stainless steel as structural material and of special interest in the context of life time extension of light water reactors in nuclear power plants. Using the DFT+U approach, a theoretical investigation on the resistance to failure of the chromium-rich inner oxide layer formed at the surface of chromium-containing austenitic alloys (stainless steel and nickel based alloys has been performed. The investigations were done for periodic bulk models. The data at the atomic scale were extrapolated by using the Universal Binding Energy Relationships (UBERs model in order to estimate the mechanical behavior of a 10 μm thick oxide scale. The calculated stress values are in good agreement with experiments. Tensile stress for the bulk chromia was observed. The effects of temperature and structural defects on cracking were investigated. The possibility of cracking intensifies at high temperature compared to 0 K investigations. Higher susceptibility to cracking was observed in presence of defects compared to nondefective oxide, in agreement with experimental observation.

  20. Estimation of spacial geo-stress components in rock samples by using the Kaiser effect of acoustic emission

    International Nuclear Information System (INIS)

    Kanagawa, Tadashi; Hayashi, Masao; Nakasa, Hiroyasu.

    1976-01-01

    The spacial remaining stress component of the rock core sample is experimentally obtained by using Kaiser effect of acoustic emission (AE), and the estimated ground pressure is compared with the natural ground pressure measured by the conventional over-coring method, in order to see the feasiblity of AE method. In this experiments of AE, 111 specimens were cut out in all directions of the rock cores (tuff) sampled from the place where the ground pressure was measured by the over-coring method, and the generation of AE caused by the load was measured. Whereby, the stress components in three directions are determined. As a result of comparison, t the AE method is proved to be effective enough to estimate the ground pressure of rock geo-dynamically. In the application of the Kaiser effect to the estimation of the geo-stress in rock samples, one of the most difficult problems is how to eliminate the obstruction of erroneous AE signals caused by the strong stress concentration at the end corners of the rock specimen. As the result of comparison, the values obtained by the AE method have a tendency of greater than the values obtained by the over-coring method. It is conceived that the AE method can easily detect the maximum stress value for geo historical long time, and that the stress concentration is apt to mix in AE method by boring. (Iwakiri, K.)

  1. Effectiveness of a Dental Students Stress Management Program

    Directory of Open Access Journals (Sweden)

    Abdullah M. Alzahem

    2015-12-01

    Full Text Available The dental education stress effects and sources were explored thoroughly in the literature, but the effectiveness of stress management programs received less attention. This study introduced a new stress management program, named Dental Education Stress Management (DESM program. It showed its effectiveness in a quasi-experimental pretest-posttest-follow-up-control group design. The new program was based on the principle of psychoeducation and consisted of three 90-min sessions, to teach dental students how to better deal with their stress symptoms and to reduce their general stress level. Two instruments were used to assess the level of stress of the dental students, namely the Dental Environment Stress questionnaire (DES, and the Psychological Stress Measure (PSM-9. Results show that the DESM program has the desired effect of decreasing the stress levels of its participants, and these effects lasted for at least two weeks. Because of several methodological limitations of the study more research is needed to draw more generalizable conclusions.

  2. Photoelastic investigation of the stresses in a stepped cylinder under internal pressure

    International Nuclear Information System (INIS)

    Sawa, Yoshiaki; Nishida, Masataka

    1985-01-01

    The states of stress distribution of the stepped cylinder under inner-pressure are studied by means of stress freezing photoelastic method. The experimental results reveal that fiber stress concentration occurs on the circular arc and hoop stress concentration occurs at the jointing point of the straight line and the arc and that each maximum value of fiver stress and hoop stress depends very greatly on the diameter of a small cylinder and the radius of curvature. And the relationship between the stress concentration factors and these shape factors are given. Effects of wall thickness on the stress concentration factors are also determined. (author)

  3. Acute effects of nandrolone decanoate on oxidative stress in isolated rat heart

    Directory of Open Access Journals (Sweden)

    Jevđević Maja

    2015-01-01

    Full Text Available Abuse of anabolic-androgenic steroids (AAS produces side effects in different tissues, with oxidative stress linked to their pathophysiology, being involved in fibrosis, cellular proliferation, and tumorigenesis. The aim of this study was to examine the acute effects of nandrolone decanoate (ND on oxidative stress in isolated rat heart. The hearts of male Wistar albino were excised and perfused according to the Langendorff technique at gradually increasing coronary perfusion pressures (40-120 cmH2O. The hearts were perfused with ND at doses of 1, 10 and 100 μM. Oxidative stress markers, including the index of lipid peroxidation (thiobarbituric acid reactive substances (TBARS, nitric oxide (nitrites; NO2-, the superoxide anion radical (O2- and hydrogen peroxide (H2O2 were measured in the coronary venous effluent. Our results showed that acute effects of ND do not promote the production of reactive oxygen species (ROS. Our finding pointed out that the highest concentration of ND may even possess some anti-oxidative potential, which should be examined further.

  4. Stress effects on framed decisions: there are differences for gains and losses

    Directory of Open Access Journals (Sweden)

    Stephan ePabst

    2013-10-01

    Full Text Available Recent studies have shown that acute stress can lead to riskier decision making. Yet, the underlying mechanisms of the stress effects on decisions under risk remain poorly understood. To gain a better understanding of decision-making processes and potential strategy application under stress, we investigated decision making in pure gain and loss domains with unequal expected values across alternatives. We conducted an experimental study with a 2 × 2 design (stress vs. no stress and gain domain vs. loss domain. The Trier Social Stress Test (TSST was utilized to induce acute stress. Controls performed the placebo-TSST. To validate the stress response we measured salivary cortisol and alpha amylase concentrations. We used a modified version of the Game of Dice Task (GDT to assess decision-making performance in a gain and a loss domain. Results showed that non-stressed participants of the gain domain decided less risky compared to those of the loss domain. This behavior is in accordance with previous studies and indicates the stability of the framing effect in even more complex tasks with changing expected values across alternatives. Stress did not alter risk taking behavior in the gain domain. Yet, in the loss domain stressed participants decided less risky compared to controls. Additionally, the data support earlier findings of longer reaction times in loss compared to gain domains due to higher cognitive effort for loss-framed decisions. It is discussed that stress may lead to reduced amygdala activation, which has been found to reduce riskier decisions in a loss domain. With respect to earlier results of riskier decisions in tasks that unite both gain and loss domains, it is discussed whether stress leads to a stronger evaluation of high gains and a neglect of losses.

  5. Stress effects on framed decisions: there are differences for gains and losses.

    Science.gov (United States)

    Pabst, Stephan; Brand, Matthias; Wolf, Oliver T

    2013-01-01

    Recent studies have shown that acute stress can lead to riskier decision making. Yet, the underlying mechanisms of the stress effects on decisions under risk remain poorly understood. To gain a better understanding of decision-making processes and potential strategy application under stress, we investigated decision making in pure gain and loss domains with unequal expected values (EVs) across alternatives. We conducted an experimental study with a 2 × 2 design (stress vs. no stress and gain domain vs. loss domain). The Trier Social Stress Test (TSST) was utilized to induce acute stress. Controls performed the placebo-TSST (p-TSST). To validate the stress response we measured salivary cortisol and alpha-amylase concentrations. We used a modified version of the Game of Dice Task (GDT) to assess decision-making performance in a gain and a loss domain. Results showed that non-stressed participants made less risky decisions in the gain domain compared to those of the loss domain. This behavior is in accordance with previous studies and indicates the stability of the framing effect in even more complex tasks with changing EVs across alternatives. Stress did not alter risk taking behavior in the gain domain. Yet, in the loss domain stressed participants made less risky decisions compared to controls. Additionally, the data support earlier findings of longer reaction times in loss compared to gain domains due to higher cognitive effort for loss-framed decisions. It is discussed that stress may lead to reduced amygdala activation, which has been found to reduce riskier decisions in a loss domain. With respect to earlier results of riskier decisions in tasks that unite both gain and loss domains, it is discussed whether stress leads to a stronger evaluation of high gains and a neglect of losses.

  6. Expectancy of Stress-Reducing Aromatherapy Effect and Performance on a Stress-Sensitive Cognitive Task

    Science.gov (United States)

    Chamine, Irina; Oken, Barry S.

    2015-01-01

    Objective. Stress-reducing therapies help maintain cognitive performance during stress. Aromatherapy is popular for stress reduction, but its effectiveness and mechanism are unclear. This study examined stress-reducing effects of aromatherapy on cognitive function using the go/no-go (GNG) task performance and event related potentials (ERP) components sensitive to stress. The study also assessed the importance of expectancy in aromatherapy actions. Methods. 81 adults were randomized to 3 aroma groups (active experimental, detectable, and undetectable placebo) and 2 prime subgroups (prime suggesting stress-reducing aroma effects or no-prime). GNG performance, ERPs, subjective expected aroma effects, and stress ratings were assessed at baseline and poststress. Results. No specific aroma effects on stress or cognition were observed. However, regardless of experienced aroma, people receiving a prime displayed faster poststress median reaction times than those receiving no prime. A significant interaction for N200 amplitude indicated divergent ERP patterns between baseline and poststress for go and no-go stimuli depending on the prime subgroup. Furthermore, trends for beneficial prime effects were shown on poststress no-go N200/P300 latencies and N200 amplitude. Conclusion. While there were no aroma-specific effects on stress or cognition, these results highlight the role of expectancy for poststress response inhibition and attention. PMID:25802539

  7. Expectancy of Stress-Reducing Aromatherapy Effect and Performance on a Stress-Sensitive Cognitive Task

    Directory of Open Access Journals (Sweden)

    Irina Chamine

    2015-01-01

    Full Text Available Objective. Stress-reducing therapies help maintain cognitive performance during stress. Aromatherapy is popular for stress reduction, but its effectiveness and mechanism are unclear. This study examined stress-reducing effects of aromatherapy on cognitive function using the go/no-go (GNG task performance and event related potentials (ERP components sensitive to stress. The study also assessed the importance of expectancy in aromatherapy actions. Methods. 81 adults were randomized to 3 aroma groups (active experimental, detectable, and undetectable placebo and 2 prime subgroups (prime suggesting stress-reducing aroma effects or no-prime. GNG performance, ERPs, subjective expected aroma effects, and stress ratings were assessed at baseline and poststress. Results. No specific aroma effects on stress or cognition were observed. However, regardless of experienced aroma, people receiving a prime displayed faster poststress median reaction times than those receiving no prime. A significant interaction for N200 amplitude indicated divergent ERP patterns between baseline and poststress for go and no-go stimuli depending on the prime subgroup. Furthermore, trends for beneficial prime effects were shown on poststress no-go N200/P300 latencies and N200 amplitude. Conclusion. While there were no aroma-specific effects on stress or cognition, these results highlight the role of expectancy for poststress response inhibition and attention.

  8. Concentration-dependent toxicity of iron oxide nanoparticles mediated by increased oxidative stress

    Directory of Open Access Journals (Sweden)

    Saba Naqvi

    2010-11-01

    Full Text Available Saba Naqvi1, Mohammad Samim2, MZ Abdin3, Farhan Jalees Ahmed4, AN Maitra5, CK Prashant6, Amit K Dinda61Faculty of Engineering and Interdisciplinary Sciences, 2Department of Chemistry, 3Department of Biotechnology, Faculty of Science, 4Department of Pharmaceutics, Faculty of Pharmacy, Jamia Hamdard, Hamdard University, 5Department of Chemistry, University of Delhi, 6Department of Pathology, All India Institute of Medical Sciences, New Delhi, IndiaAbstract: Iron oxide nanoparticles with unique magnetic properties have a high potential for use in several biomedical, bioengineering and in vivo applications, including tissue repair, magnetic resonance imaging, immunoassay, drug delivery, detoxification of biologic fluids, cell sorting, and hyperthermia. Although various surface modifications are being done for making these nonbiodegradable nanoparticles more biocompatible, their toxic potential is still a major concern. The current in vitro study of the interaction of superparamagnetic iron oxide nanoparticles of mean diameter 30 nm coated with Tween 80 and murine macrophage (J774 cells was undertaken to evaluate the dose- and time-dependent toxic potential, as well as investigate the role of oxidative stress in the toxicity. A 15–30 nm size range of spherical nanoparticles were characterized by transmission electron microscopy and zeta sizer. MTT assay showed >95% viability of cells in lower concentrations (25–200 µg/mL and up to three hours of exposure, whereas at higher concentrations (300–500 µg/mL and prolonged (six hours exposure viability reduced to 55%–65%. Necrosis-apoptosis assay by propidium iodide and Hoechst-33342 staining revealed loss of the majority of the cells by apoptosis. H2DCFDDA assay to quantify generation of intracellular reactive oxygen species (ROS indicated that exposure to a higher concentration of nanoparticles resulted in enhanced ROS generation, leading to cell injury and death. The cell membrane injury

  9. Effect of Nitrogen Nutritional Stress on Some Growth Parameters of Zea mays L. and Vigna unguiculata (L. Walp.

    Directory of Open Access Journals (Sweden)

    Akinbode Foluso OLOGUNDUDU

    2013-02-01

    Full Text Available This study investigated the responses of maize (Zea mays L. and cowpea (Vigna unguiculata L. Walp. seedlings growth parameters to nitrogen nutritional stress. This was with a view to determining whether nitrogen nutritional stress would retard or enhance maize and cowpea growth, partly, wholly or not at all through its effect on biomass accumulation and some morphological parameters. Germination of seeds was done using treated sand in sixty plastic pots. A group of the seedlings was nutrient stressed by administering 200 ml of complete nutrient solution minus nitrogen (-N while the other groups were fed with five times (X5N and ten times (X10N the optimal concentration of nitrogen and the last regime was fed with full nutrient solution (FN. The effects of optimal concentration and nitrogen stress on the growth rates (as measured by their fresh and dry weight were studied. The result of the growth analysis showed that there was increase in shoot height with supraoptimal concentrations of nitrogen treatments (X10N and X5N while there was a decrease in shoot height with minus nitrogen (-N regimes. The observed higher biomass (dry matter yield under the FN regimes in both Zea mays and Vigna unguiculata were attributed to optimal nutrient assimilation rate.

  10. Influence of structural parameter included in nonlocal rock mass model on stress concentration around circular tunnel

    Science.gov (United States)

    Lavrikov, SV; Mikenina, OA; Revuzhenko, AF

    2018-03-01

    A model of elastic body, including local curvature of elementary volume, is matched with a nonlocal model with a linear structural parameter in the differential approximation. The problem on deformation of rock mass around a circular cross section tunnel is solved numerically. The contours of the calculated stresses are plotted. It is shown that inclusion of local bends in the model results in expansion of influence zone of the tunnel and reduces stress concentration factor at the tunnel boundary.

  11. The antioxidative system of Norway spruce: Effects of different stress factors. Das antioxidative System der Fichte: Einfluss von verschiedenen Stressfaktoren

    Energy Technology Data Exchange (ETDEWEB)

    Schittenhelm, J. (Freiburg Univ., Inst. fuer Biologie 2, Abt. Botanik (Germany)); Westphal, S. (Freiburg Univ., Inst. fuer Biologie 2, Abt. Botanik (Germany)); Toder, S. (Freiburg Univ., Inst. fuer Biologie 2, Abt. Botanik (Germany)); Wagner, E. (Freiburg Univ., Inst. fuer Biologie 2, Abt. Botanik (Germany))

    1993-08-01

    The effects of different stress factors on the antioxidative system of 6-year-old Norway spruces of the same clone were examined. Flooding and permanent darkness had only minor effects. On the other hand drought, chilling, intense light, and very high ozone concentrations showed strong but distinct consequences. This indicates that the damages by these stress factors are due to different toxic oxygen species, and that the stress factors could produce synergistic damages under natural field conditions. (orig.)

  12. Serum thiamine concentration and oxidative stress as predictors of mortality in patients with septic shock.

    Science.gov (United States)

    Costa, Nara Aline; Gut, Ana Lúcia; de Souza Dorna, Mariana; Pimentel, José Alexandre Coelho; Cozzolino, Silvia Maria Franciscato; Azevedo, Paula Schmidt; Fernandes, Ana Angélica Henrique; Zornoff, Leonardo Antonio Mamede; de Paiva, Sergio Alberto Rupp; Minicucci, Marcos Ferreira

    2014-04-01

    The purpose of the study is to determine the influence of serum thiamine, glutathione peroxidase (GPx) activity, and serum protein carbonyl concentrations in hospital mortality in patients with septic shock. This prospective study included all patients with septic shock on admission or during intensive care unit (ICU) stay, older than 18 years, admitted to 1 of the 3 ICUs of the Botucatu Medical School, from January to August 2012. Demographic information, clinical evaluation, and blood sample were taken within the first 72 hours of the patient's admission or within 72 hours after septic shock diagnosis for serum thiamine, GPx activity, and protein carbonyl determination. One hundred eight consecutive patients were evaluated. The mean age was 57.5 ± 16.0 years, 63% were male, 54.6% died in the ICU, and 71.3% had thiamine deficiency. Thiamine was not associated with oxidative stress. Neither vitamin B1 levels nor the GPx activity was associated with outcomes in these patients. However, protein carbonyl concentration was associated with increased mortality. In patients with septic shock, oxidative stress was associated with mortality. On the other hand, thiamine was not associated with oxidative stress or mortality in these patients. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Hypothalamic kappa opioid receptor mediates both diet-induced and melanin concentrating hormone-induced liver damage through inflammation and endoplasmic reticulum stress.

    Science.gov (United States)

    Imbernon, Monica; Sanchez-Rebordelo, Estrella; Romero-Picó, Amparo; Kalló, Imre; Chee, Melissa J; Porteiro, Begoña; Al-Massadi, Omar; Contreras, Cristina; Fernø, Johan; Senra, Ana; Gallego, Rosalia; Folgueira, Cintia; Seoane, Luisa M; van Gestel, Margriet; Adan, Roger A; Liposits, Zsolt; Dieguez, Carlos; López, Miguel; Nogueiras, Ruben

    2016-10-01

    The opioid system is widely known to modulate the brain reward system and thus affect the behavior of humans and other animals, including feeding. We hypothesized that the hypothalamic opioid system might also control energy metabolism in peripheral tissues. Mice lacking the kappa opioid receptor (κOR) and adenoviral vectors overexpressing or silencing κOR were stereotaxically delivered in the lateral hypothalamic area (LHA) of rats. Vagal denervation was performed to assess its effect on liver metabolism. Endoplasmic reticulum (ER) stress was inhibited by pharmacological (tauroursodeoxycholic acid) and genetic (overexpression of the chaperone glucose-regulated protein 78 kDa) approaches. The peripheral effects on lipid metabolism were assessed by histological techniques and western blot. We show that in the LHA κOR directly controls hepatic lipid metabolism through the parasympathetic nervous system, independent of changes in food intake and body weight. κOR colocalizes with melanin concentrating hormone receptor 1 (MCH-R1) in the LHA, and genetic disruption of κOR reduced melanin concentrating hormone-induced liver steatosis. The functional relevance of these findings was given by the fact that silencing of κOR in the LHA attenuated both methionine choline-deficient, diet-induced and choline-deficient, high-fat diet-induced ER stress, inflammation, steatohepatitis, and fibrosis, whereas overexpression of κOR in this area promoted liver steatosis. Overexpression of glucose-regulated protein 78 kDa in the liver abolished hypothalamic κOR-induced steatosis by reducing hepatic ER stress. This study reveals a novel hypothalamic-parasympathetic circuit modulating hepatic function through inflammation and ER stress independent of changes in food intake or body weight; these findings might have implications for the clinical use of opioid receptor antagonists. (Hepatology 2016;64:1086-1104). © 2016 The Authors. (Hepatology published by Wiley Periodicals, Inc., on

  14. The effects of stress on nuclear power plant operational decision making and training approaches to reduce stress effects

    International Nuclear Information System (INIS)

    Mumaw, R.J.

    1994-08-01

    Operational personnel may be exposed to significant levels of stress during unexpected changes in plant state an plant emergencies. The decision making that identifies operational actions, which is strongly determined by procedures, may be affected by stress, and performance may be impaired. ER report analyzes potential effects of stress in nuclear power plant (NPP) settings, especially in the context of severe accident management (SAM). First, potential sources of stress in the NPP setting are identified. This analysis is followed by a review of the ways in which stress is likely to affect performance, with an emphasis on performance of cognitive skills that are linked to operational decision making. Finally, potential training approaches for reducing or eliminating stress effects are identified. Several training approaches have the potential to eliminate or mitigate stress effects on cognitive skill performance. First, the use of simulated events for training can reduce the novelty and uncertainty that can lead to stress and performance impairments. Second, training to make cognitive processing more efficient and less reliant on attention and memory resources can offset the reductions in these resources that occur under stressful conditions. Third, training that targets crew communications skills can reduce the likelihood that communications will fail under stress

  15. The effects of stress on nuclear power plant operational decision making and training approaches to reduce stress effects

    Energy Technology Data Exchange (ETDEWEB)

    Mumaw, R.J.

    1994-08-01

    Operational personnel may be exposed to significant levels of stress during unexpected changes in plant state an plant emergencies. The decision making that identifies operational actions, which is strongly determined by procedures, may be affected by stress, and performance may be impaired. ER report analyzes potential effects of stress in nuclear power plant (NPP) settings, especially in the context of severe accident management (SAM). First, potential sources of stress in the NPP setting are identified. This analysis is followed by a review of the ways in which stress is likely to affect performance, with an emphasis on performance of cognitive skills that are linked to operational decision making. Finally, potential training approaches for reducing or eliminating stress effects are identified. Several training approaches have the potential to eliminate or mitigate stress effects on cognitive skill performance. First, the use of simulated events for training can reduce the novelty and uncertainty that can lead to stress and performance impairments. Second, training to make cognitive processing more efficient and less reliant on attention and memory resources can offset the reductions in these resources that occur under stressful conditions. Third, training that targets crew communications skills can reduce the likelihood that communications will fail under stress.

  16. EDXS and XRD Analyses of Coleus with Different Concentration Selenium Supplements Under Lead Stress

    Directory of Open Access Journals (Sweden)

    QIN Hui-yuan

    2014-04-01

    Full Text Available In order to study the changes of the morphologies and element composition in Coleus hlumei Benth(Coleusroots and leaves under1.0 mmol·L-1 Pb2+ stress with selenium ( Setreatments, and to preliminarily investigate the relief mechanism of Se level on lead toxicity from the perspective of spectroscopy, Coleus was cultivated in nutrient solutions with different concentrations of Se. The results showed that the content of C, K and Ca elements in roots decreased, while 0, Mg, Al, Si, Fe and Pb elements increased under Pb stress with Se treatments. In addi-tion, the content of C, Mg, Al, Si, K, Ca and Fe elements in leaves decreased, while 0 and Cl elements increased. The element species and its contents in roots were changed obviously under Pb stress with Se treatments, and crystalline solid and crystal phase in roots were correspond-ingly changed.

  17. Oxidative stress suppresses the cellular bioenergetic effect of the 3-mercaptopyruvate sulfurtransferase/hydrogen sulfide pathway

    International Nuclear Information System (INIS)

    Módis, Katalin; Asimakopoulou, Antonia; Coletta, Ciro; Papapetropoulos, Andreas; Szabo, Csaba

    2013-01-01

    Highlights: •Oxidative stress impairs 3-MST-derived H 2 S production in isolated enzyme and in isolated mitochondria. •This impairs the stimulatory bioenergetic effects of H 2 S in hepatocytes. •This has implications for the pathophysiology of diseases with oxidative stress. -- Abstract: Recent data show that lower concentrations of hydrogen sulfide (H 2 S), as well as endogenous, intramitochondrial production of H 2 S by the 3-mercaptopyruvate (3-MP)/3-mercaptopyruvate sulfurtransferase (3-MST) pathway serves as an electron donor and inorganic source of energy to support mitochondrial electron transport and ATP generation in mammalian cells by donating electrons to Complex II. The aim of our study was to investigate the role of oxidative stress on the activity of the 3-MP/3-MST/H 2 S pathway in vitro. Hydrogen peroxide (H 2 O 2 , 100–500 μM) caused a concentration-dependent decrease in the activity of recombinant mouse 3-MST enzyme. In mitochondria isolated from murine hepatoma cells, H 2 O 2 (50–500 μM) caused a concentration-dependent decrease in production of H 2 S from 3-MP. In cultured murine hepatoma cells H 2 O 2 , (3–100 μM), did not result in overall cytotoxicity, but caused a partial decrease in basal oxygen consumption and respiratory reserve rapacity. The positive bioenergetic effect of 3-MP (100–300 nM) was completely abolished by pre-treatment of the cells with H 2 O 2 (50 μM). The current findings demonstrate that oxidative stress inhibits 3-MST activity and interferes with the positive bioenergetic role of the 3-MP/3-MST/H 2 S pathway. These findings may have implications for the pathophysiology of various conditions associated with increased oxidative stress, such as various forms of critical illness, cardiovascular diseases, diabetes or physiological aging

  18. Opposite Effects of Stress on Pain Modulation Depend on the Magnitude of Individual Stress Response.

    Science.gov (United States)

    Geva, Nirit; Defrin, Ruth

    2018-04-01

    The effect of acute stress on pain threshold and intolerance threshold are reported as producing either hypoalgesia or hyperalgesia. Yet, the contribution of individual stress reactivity in this respect has not been established. The aim was to test 2 pain modulation paradigms under acute stress manipulation, to our knowledge, for the first time, to study whether stress differentially affects pain modulation, and whether the effect is related to individual stress response. Participants were 31 healthy subjects. Conditioned pain modulation (CPM) and pain adaptation were measured before and after inducing an acute stress response using the Montreal Imaging Stress Task. Subjects' stress response was evaluated according to salivary cortisol, autonomic function, and perceived stress and anxiety. The Montreal Imaging Stress Task induced a validated stress response. On a group level, stress induced reduction in CPM magnitude and increase in pain adaptation compared with baseline. These responses correlated with stress reactivity. When the group was subdivided according to stress reactivity, only high stress responders exhibited reduced CPM whereas only low stress responders exhibited increased pain adaptation. The results suggest that acute stress may induce opposite effects on pain modulation, depending on individual stress reactivity magnitude, with an advantage to low stress responders. This study evaluated the effect of acute stress on pain modulation. Pain modulation under stress is affected by individual stress responsiveness; decreased CPM occurs in high stress responders whereas increased pain adaptation occurs in low stress responders. Identification of high stress responders may promote better pain management. Copyright © 2017 The American Pain Society. Published by Elsevier Inc. All rights reserved.

  19. Psychological stress-relieving effects of chewing - Relationship between masticatory function-related factors and stress-relieving effects.

    Science.gov (United States)

    Tasaka, Akinori; Kikuchi, Manaki; Nakanishi, Kousuke; Ueda, Takayuki; Yamashita, Shuichiro; Sakurai, Kaoru

    2018-01-01

    The objective of the present study was to investigate the relationship between masticatory function-related factors (masticatory performance, occlusal contact area, maximum bite force, number of chewing strokes, and muscle activity) and the stress-relieving effects of chewing. A total of 28 healthy male subjects were instructed to rest or chew for 10min after 30min of stress loading with arithmetic calculations. Their stress state was assessed by measuring salivary cortisol levels. Saliva was collected at three time points: before stress loading, immediately after stress loading, and 10min after stress loading. Compared to resting, chewing produced a significantly greater reduction in the rate of change in salivary cortisol levels 10min after stress loading. A negative correlation was observed between the rate of decrease in salivary cortisol levels and the number of chewing strokes. No significant correlation was observed between the rate of decrease in salivary cortisol levels and other measurement items. In healthy dentulous people, the number of chewing strokes has been shown to be a masticatory function-related factor that affects stress relief from chewing, suggesting the possibility that more appropriate chewing would produce a greater effect psychological stress relief. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  20. Effect of Crack Tip Stresses on Delayed Hydride Cracking in Zr-2.5Nb Tubes

    International Nuclear Information System (INIS)

    Kim, Young Suk; Cheong, Yong Moo

    2007-01-01

    Delayed hydride cracking (DHC) tests have shown that the DHC velocity becomes faster in zirconium alloys with a higher yield stress. To account for this yield stress effect on the DHC velocity, they suggested a simple hypothesis that increased crack tip stresses due to a higher yield stress would raise the difference in hydrogen concentration between the crack tip and the bulk region and accordingly the DHC velocity. This hypothesis is also applied to account for a big leap in the DHC velocity of zirconium alloys after neutron irradiation. It should be noted that this is based on the old DHC models that the driving force for DHC is the stress gradient. Puls predicted that an increase in the yield stress of a cold worked Zr-2.5Nb tube due to neutron irradiation by about 300 MPa causes an increase of its DHC velocity by an order of magnitude or 2 to 3 times depending on the accommodation energy values. Recently, we proposed a new DHC model that a driving force for DHC is not the stress gradient but the concentration gradient arising from the stress-induced precipitation of hydrides at the crack tip. Our new DHC model and the supporting experimental results have demonstrated that the DHC velocity is governed primarily by hydrogen diffusion at below 300 .deg. C. Since hydrogen diffusion in Zr-2.5Nb tubes is dictated primarily by the distribution of the β-phase, the DHC velocity of the irradiated Zr-2.5Nb tube must be determined mainly by the distribution of the β-phase, not by the increased yield stress, which is in contrast with the hypothesis of the previous DHC models. In short, a controversy exists as to the effect on the DHC velocity of zirconium alloys of a change in the crack tip stresses by irradiation hardening or cold working or annealing. The aim of this study is to resolve this controversy and furthermore to prove the validity of our DHC model. To this end, we cited Pan et al.'s experiment where the delayed hydride cracking velocity, the tensile strengths

  1. Isolation of Crude Oil from Polluted Waters Using Biosurfactants Pseudomonas Bacteria: Assessment of Bacteria Concentration Effects

    Directory of Open Access Journals (Sweden)

    A. Khalifeh

    2013-04-01

    Full Text Available Biological decomposition techniques and isolation of environmental pollutions using biosurfactants bacteria are effective methods of environmental protection. Surfactants are amphiphilic compounds that are produced by local microorganisms and are able to reduce the surface and the stresses between surfaces. As a result, they will increase solubility, biological activity, and environmental decomposition of organic compounds. This study analyzes the effects of biosurfactants on crude oil recovery and its isolation using pseudomonas sea bacteria species. Preparation of biosurfactants was done in glass flasks and laboratory conditions. Experiments were carried out to obtain the best concentration of biosurfactants for isolating oil from water and destroying oil-in-water or water-in-oil emulsions in two pH ranges and four saline solutions of different concentrations. The most effective results were gained when a concentration of 0.1% biosurfactants was applied.

  2. Effects of rumen-protected γ-aminobutyric acid on performance and nutrient digestibility in heat-stressed dairy cows.

    Science.gov (United States)

    Cheng, J B; Bu, D P; Wang, J Q; Sun, X Z; Pan, L; Zhou, L Y; Liu, W

    2014-09-01

    This experiment was conducted to investigate the effects of rumen-protected γ-aminobutyric acid (GABA) on performance and nutrient digestibility in heat-stressed dairy cows. Sixty Holstein dairy cows (141±15 d in milk, 35.9±4.3kg of milk/d, and parity 2.0±1.1) were randomly assigned to 1 of 4 treatments according to a completely randomized block design. Treatments consisted of 0 (control), 40, 80, or 120mg of true GABA/kg of dry matter (DM). The trial lasted 10wk. The average temperature-humidity indices at 0700, 1400, and 2200h were 78.4, 80.2, and 78.7, respectively. Rectal temperatures decreased linearly at 0700, 1400, and 2200h with increasing GABA concentration. Supplementation of GABA had no effect on respiration rates at any time point. Dry matter intake, energy-corrected milk, 4% fat-corrected milk, and milk fat yield tended to increase linearly with increasing GABA concentration. Supplementation of GABA affected, in a quadratic manner, milk protein and lactose concentrations, and milk protein yield, and the peak values were reached at a dose of 40mg of GABA/kg. Milk urea nitrogen concentration responded quadratically. Total solids content increased linearly with increasing GABA concentration. Supplementation of GABA had no effect on milk yield, lactose production, total solids, milk fat concentration, somatic cell score, or feed efficiency. Apparent total-tract digestibilities of DM, organic matter, crude protein, neutral detergent fiber, and acid detergent fiber were similar among treatments. These results indicate that rumen-protected GABA supplementation to dairy cows can alleviate heat stress by reducing rectal temperature, increase DM intake and milk production, and improve milk composition. The appropriate supplemental GABA level for heat-stressed dairy cows is 40mg/kg of DM. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  3. The effects of therapeutic concentrations ofamisulpride andrisperidone on human plasma lipid peroxidation – invitro studies

    Directory of Open Access Journals (Sweden)

    Anna Dietrich-Muszalska

    2011-09-01

    Full Text Available Introduction: Antipsychotics may in different ways affect the oxidative stress measured by plasma lipid peroxidation. Probably some of them may intensify the oxidative balance disturbances occurring in schizophrenia. The effects of amisulpride and risperidone on redox processes are not known sufficiently yet. Aim of the study: Establishment of the effects of amisulpride and risperidone on human plasma lipid peroxidation measured by determination of the level of thiobarbituric acid-reactive substances (TBARS, in vitro. Material and methods: Blood for the studies was collected from healthy volunteers (aged 24-26 years for ACD solution. Active substances of the examined drugs were dissolved in 0.01% dimethylsulfoxide (DMSO to the final concentrations (of amisulpride 578 ng/ml and risperidone 64 ng/ml and incubated with plasma for 1 and 24 hours at 37ºC. For each experiment the control samples of plasma with DMSO (without the drug were performed. The lipid peroxidation level was measured in plasma by determining the TBARS concentration, using the spectrophotometric method (acc. to Rice-Evans, 1991. The results were analysed using the following statistical methods: the paired Student t-test and ANOVA II variance analysis and NIR test (StatSoft Inc., Statistica v. 6.0. Results: The ANOVA II variance analysis indicated significant differences in the effects of both drugs on TBARS level (F=4.26; df=2, p0.05. Conclusion: Amisulpride and risperidone in concentrations corresponding to doses recommended for treatment of acute episode of schizophrenia do not induce oxidative stress measured by lipid peroxidation. Unlike risperidone, amisulpride exhibits antioxidative effects.

  4. Stress Effects on Multiple Memory System Interactions

    OpenAIRE

    Ness, Deborah; Calabrese, Pasquale

    2016-01-01

    Extensive behavioural, pharmacological, and neurological research reports stress effects on mammalian memory processes. While stress effects on memory quantity have been known for decades, the influence of stress on multiple memory systems and their distinct contributions to the learning process have only recently been described. In this paper, after summarizing the fundamental biological aspects of stress/emotional arousal and recapitulating functionally and anatomically distinct memory syst...

  5. Determining stress fields of shearer-loader picks

    Energy Technology Data Exchange (ETDEWEB)

    Luszczkiewicz, J; Sikora, W

    1987-06-01

    Analyzes factors which influence stress distribution in the NK-4 shearer-loader picks during coal cutting. The AFT optically active cover, 0.0015 mm thick, was used. The pick with the AFT cover was loaded using a force of 33 kN. Isoclinic lines showing stress distribution were photographed. Effects of pick design and its holder type on stress distribution were investigated. Investigations showed that distribution of normal stresses in a pick shaft has a non-linear character. The hole in a pick shaft increased stress concentration in that shaft section. Eliminating the hole reduced stress concentration. Reducing shaft length by about 20 mm did not increase stresses in that shaft zone. 15 refs.

  6. Corrosion in low dielectric constant Si-O based thin films: Buffer concentration effects

    International Nuclear Information System (INIS)

    Zeng, F. W.; Lane, M. W.; Gates, S. M.

    2014-01-01

    Organosilicate glass (OSG) is often used as an interlayer dielectric (ILD) in high performance integrated circuits. OSG is a brittle material and prone to stress-corrosion cracking reminiscent of that observed in bulk glasses. Of particular concern are chemical-mechanical planarization techniques and wet cleans involving solvents commonly encountered in microelectronics fabrication where the organosilicate film is exposed to aqueous environments. Previous work has focused on the effect of pH, surfactant, and peroxide concentration on the subcritical crack growth of these films. However, little or no attention has focused on the effect of the conjugate acid/base concentration in a buffer. Accordingly, this work examines the “strength” of the buffer solution in both acidic and basic environments. The concentration of the buffer components is varied keeping the ratio of acid/base and therefore pH constant. In addition, the pH was varied by altering the acid/base ratio to ascertain any additional effect of pH. Corrosion tests were conducted with double-cantilever beam fracture mechanics specimens and fracture paths were verified with ATR-FTIR. Shifts in the threshold fracture energy, the lowest energy required for bond rupture in the given environment, G TH , were found to shift to lower values as the concentration of the base in the buffer increased. This effect was found to be much larger than the effect of the hydroxide ion concentration in unbuffered solutions. The results are rationalized in terms of the salient chemical bond breaking process occurring at the crack tip and modeled in terms of the chemical potential of the reactive species

  7. The effects of oil sands wastewater on fish resulting from exposure to sub-lethal concentrations

    International Nuclear Information System (INIS)

    Birkholz, D.A.; Goudey, J.S.; Balch, G.C.; Nelson, L.R.; MacKinnon, M.

    1995-01-01

    Rainbow trout, Oncorhynchus mykiss, were exposed to sub-lethal concentrations of oil sands wastewater in flow through laboratory experiments as well as to artificial ponds containing sub-lethal concentrations of tailings pond water and fine tails in order to study the viability of the wet landscape remediation option. Large (200--300 g) fish were used for all the exposures in this preliminary study and the following data were collected: blood cell counts, sex hormone concentrations, sexual maturation, stress protein concentrations, PAH-metabolites in bile, condition factors, liver somatic indices, mixed function oxygenase induction, PAHs in muscle, external condition and the condition of internal organs. The data obtained from this study revealed no adverse effects upon fish during extended field exposures. Given similar exposure conditions in the release waters of a wet landscape reclamation, the data suggest that there may be no adverse effects upon fish, however, longer term studies, other indicator organisms and additional chronic tests should be conducted

  8. [Effect of melafen on expression of Elip1 and Elip2 genes encoding chloroplast light-induced stress proteins in barley].

    Science.gov (United States)

    Osipenkova, O V; Ermokhina, O V; Belkina, G G; Oleskina, Iu P; Fattakhov, S G; Iurina, N P

    2008-01-01

    The effect of melafen, a plant growth regulator of a new generation, on the growth, pigment composition, and expression of nuclear genes Elip1 and Elip2 encoding chloroplast light-stress proteins in barley (Hordeum vulgare L) seedlings was studied. It is shown that the height of seedlings treated with melafen at concentrations of 0.5 x 10(-10) and 0.5 x 10(-8) M increased by approximately 10 and 20%, respectively, as compared to the control. At high concentrations (10(-5) and 10(-3) M), melafen had no effect on the growth of seedlings. The content of chlorophylls and carotenoids in chloroplasts barely differed from the control at all melafen concentrations tested. Reverse transcription-polymerase chain reaction (RT-PCR) showed that melafen did not influence the expression of the nuclear gene encoding the low-molecular-weight plastid stress protein ELIP1. At the same time, the expression of the nuclear gene encoding the high-molecular-weight light-inducible stress protein ELIP2 in the plants treated with melafen at a concentration of 0.5 x 10(-8) M, increased by approximately 70 %. At higher concentrations, melafen suppressed the Elip2 gene expression. Thus, melafen affects the expression of the Elip2 gene, which is involved in the regulation of chlorophyll synthesis and chloroplast biogenesis, which, in turn, may lead to changes in the resistance of plants to light-induced stress.

  9. Effects of stress temperatures of germination on polyamine titers of soybean seeds

    Science.gov (United States)

    Pineda-Mejia, Renan

    High and low stress temperatures during seed germination and seedling development limit total germination and the rate of germination and growth. Changes in polyamine (PA) concentrations in seeds of different species have been associated with germination, growth and environmental stresses such as temperature, drought, oxygen, chilling injury and osmotic conditions. Two studies were conducted to determine the effect of stress temperatures during germination and seedling development on polyamine titers in soybean seeds. Three germination temperatures, 25, 30, and 36°C were used in the first study to evaluate their influence on changes in polyamine concentrations in soybean seeds germinated at 76 and 90 hours. The polyamines (PAs), cadaverine (Cad), putrescine (Put), spermidine (Spd), agmatine (Agm), and spermine (Spin) were quantified by HPLC using a cation exchange column and an electrochemical detector. Cad, Put, Agm, and Spd declined as the germination temperatures increased from 25 to 36°C. Conversely, Spin increased considerably with an increase in temperature. Total germination was reduced from 97.2 to 92.5% as germination temperatures increased from 25 to 36°C. Germination time did not affect Cad, Agm and Spm, and total germination, however, the interaction between temperature and germination time for Put and Spd concentrations was significant. In the second study, changes in PA concentrations, seedling growth, germination time (t50), fresh and dry weight, and moisture content were measured in the embryonic axis and cotyledons of soybean seeds germinated at 10 and 25°C through six stages of germination dry seed (DS), testa split (TS), radicle at 10 mm (Ra-10), root hairs visible (RHV), secondary root primordia (SRP), and complete seedling (CS). The concentrations of Cad and Put in the embryonic axis, were significantly higher in seeds germinated under low temperature than in seeds at 25°C (approximately 10 and 3 fold respectively). However, this

  10. On a class of problems on interaction of stress concentrators of different types with an elastic semi-infinite plate

    Science.gov (United States)

    Mkhitaryan, S. M.

    2018-04-01

    A class of mixed boundary-value problems of mathematical theory of elasticity dealing with interaction between stress concentrators of different types (such as cracks, absolutely rigid thin inclusions, punches, and stringers) and an elastic semi-infinite plate is considered. The method of Mellin integral transformation is used to reduce solving these problems to solving singular integral equations (SIE). After the governing SIE are solved, the following characteristics of the problem are determined: tangential contact stresses under stringers, dislocation density on the crack edges, breaking stresses outside the cracks on their line of location, the stress intensity factor (SIF), crack openings, jumps of contact stresses on the edges of inclusions.

  11. Rheology of concentrated biomass

    Science.gov (United States)

    J.R. Samaniuk; J. Wang; T.W. Root; C.T. Scott; D.J. Klingenberg

    2011-01-01

    Economic processing of lignocellulosic biomass requires handling the biomass at high solids concentration. This creates challenges because concentrated biomass behaves as a Bingham-like material with large yield stresses. Here we employ torque rheometry to measure the rheological properties of concentrated lignocellulosic biomass (corn stover). Yield stresses obtained...

  12. Effect of Foliar Application of Chitosan on Growth and Biochemical Characteristics of Safflower (Carthamus tinctorius L. under Water Deficit Stress

    Directory of Open Access Journals (Sweden)

    batool mahdavi

    2014-09-01

    Full Text Available In order to study the effects of water deficit stress and foliar application of chitosan in safflower (Carthamus tinctorius L., a pot experiment was conducted in 2009. Experimental design was a randomized complete block in factorial arrangement with three replications. Experimental factors were water deficit levels (unstressed (control and 70% available water depletion from soil (water deficit stress, chitosan concentrations (0, 0.05, 0.1%, all dissolved in 1% acetic acid along with an additional treatment of distilled water and foliar application times (before and during stem elongation. The results showed that water deficit stress reduced plant height, leaf area, shoot and root dry weight, root height and volume. Whereas, foliar application of chitosan increased mentioned traits. In addition, water deficit stress decreased chlorophyll fluorescence, chlorophyll concentration and relative water content. Carotenoid, proline and malondialdehyde (MDA content were increased in response to stress. Foliar application of chitosan increased chlorophyll fluorescence, relative water content (68.77% and chlorophyll b in the water deficit stressed plants, whereas decreased MDA content. The results of the present study indicate that application of chitosan can reduce the harmful effects of water deficit and improve plant growth.

  13. Effect of adaptation and heat stress on reproductive performances of fat-tail Awassi rams in eastern mediterranean

    International Nuclear Information System (INIS)

    Abi Saab, S.; Darwish, W.Y.; Aad, P.; Sleiman, F.T.; Kallassy, N.; Aad, Y.

    2011-01-01

    The Awassi fat-tail sheep is desired in the Middle East and Sahara for its hardiness and resistance. In this region, the adaptability of Awassi rams to elevated heat stress is controversial. The objective of this study was to assess the effect of ambient or testicular 43 deg C heat on semen characteristics. 12 Awassi rams of 1.2 to 2 years were allowed an initial adaptation period (P0), followed by two experimental phases (P1 and P2), each including a period of heat stress (HS1 and HS2) followed by a period of recovery from heat stress (R1and R2). Heat stress conditions were considered when ambient temperature (Group 2) or testicular environment (Group 3) reached 42 to 44 deg C. Control animals (Group 1) were exposed to ambient environmental conditions. Temperature-humidity index (THI) as a relationship of ambient temperature, wet and dry humidity effect along with respiration and pulse rate, body temperature and live body weight (BW) were measured weekly as adaptation parameters. Reproductive parameters assessed included scrotum circumference and testicular volume measured twice per heat stress period, whereas semen volume density,concentration and motility were measured twice weekly. Data were analyzed using the mixed procedure of SAS under a time series analysis model, with treatment and time nested within period as main effects, and treatment by time within period as interaction terms. Treatment means were separated using Fisher protected LSD. Results showed a THI of 25.7 during therest periods (R1 and R2), 30 during HS1 and 28 during HS2. BW decreased with ambient stress, whereas respiration rate increased during heat stress periods (HS1 and HS2). Testes volume decreased with both ambient and testicular heat stress, whereas testicular circumference was not affected by these conditions. Semen concentration decreased whereas semen volume increased with ambient but not testicular heat stress. Spermatozoa abnormalities increased in R1 following heat stress (HS1

  14. The effects of exogenous proline and osmotic stress on morpho ...

    African Journals Online (AJOL)

    USER

    2010-06-21

    Jun 21, 2010 ... For evaluation of growth parameters of strawberry callus under osmotic stress and exogenous proline, embryonic calli were transferred to Murashige and Skoog (MS) medium containing four sucrose. (osmotic stress) treatments including 3, 6, 9 and 12% and various concentrations of exogenous L- proline ...

  15. Approximate methods and working rules for peak stress effects

    International Nuclear Information System (INIS)

    Jobson, D.A.

    1983-01-01

    In order to assess stress concentration effects and associated strain intensification at notches, Neuber's work on this subject is used frequently. Neuber refers to a particular nonlinear stress-strain relation which, he observed, led to the same deferential equation for the lateral displacements as that found by Chaplygin for the velocity potential of compressible flow. for a linearized adiabatic law. This finding has been examined by studying torsion problems, which Involve warping displacements. Although a deformation law of the type τ(γ) has been assumed, the shear strain components remain 'proportional' to the corresponding stress components for problems of the type considered. It has been found that the governing equations and boundary conditions for φ may be made completely analogous to those for the velocity potential of a corresponding compressible flow in a prismatic cylinder of the same shape as that of the solid bar, provided that the constitutive equation. for the solid and the gas correspond in a defined sense. This embodied Neuber's observation, which was restricted to a particular stress strain law, namely that which corresponded to a linear adiabatic gas relationship. The above finding also assimilates a well-known hydrodynamic analogy, to which it reduces for linearly elastic materials. Corresponding governing equations have further been established for the stress function and these have similarly been related to those for an analogous stream function, defined by reference to the flow density of the corresponding compressible fluid

  16. Effects of supplemental feeding and aggregation on fecal glucocorticoid metabolite concentrations in elk

    Science.gov (United States)

    Forristal, Victoria E.; Creel, Scott; Taper, Mark L.; Scurlock, Brandon M.; Cross, Paul C.

    2012-01-01

    Habitat modifications and supplemental feeding artificially aggregate some wildlife populations, with potential impacts upon contact and parasite transmission rates. Less well recognized, however, is how increased aggregation may affect wildlife physiology. Crowding has been shown to induce stress responses, and increased glucocorticoid (GC) concentrations can reduce immune function and increase disease susceptibility. We investigated the effects of supplemental feeding and the aggregation that it induces on behavior and fecal glucocorticoid metabolite concentrations (fGCM) in elk (Cervus elaphus) using observational and experimental approaches. We first compared fGCM levels of elk on supplemental feedgrounds to neighboring elk populations wintering in native habitats using data from 2003 to 2008. We then experimentally manipulated the distribution of supplemental food on feedgrounds to investigate whether more widely distributed food would result in lower rates of aggression and stress hormone levels. Contrary to some expectations that fed elk may be less stressed than unfed elk during the winter, we found that elk on feedgrounds had fecal GC levels at least 31% higher than non-feedground populations. Within feedgrounds, fGCM levels were strongly correlated with local measures of elk density (r2 = 0.81). Dispersing feed more broadly, however, did not have a detectable effect on fGCM levels or aggression rates. Our results suggest that increases in aggregation associated with winter feedgrounds affects elk physiology, and the resulting increases in fGCM levels are not likely to be mitigated by management efforts that distribute the feed more widely. Additional research is needed to assess whether these increases in fGCMs directly alter parasite transmission and disease dynamics.

  17. Effective stress law for anisotropic elastic deformation

    International Nuclear Information System (INIS)

    Carroll, M.M.

    1979-01-01

    An effective stress law is derived analytically to describe the effect of pore fluid pressure on the linearly elastic response of saturated porous rocks which exhibit anisotropy. For general anisotropy the difference between the effective stress and the applied stress is not hydrostatic. The effective stress law involves two constants for transversely isotropic response and three constants for orthotropic response; these constants can be expressed in terms of the moduli of the porous material and of the solid material. These expressions simplify considerably when the anisotropy is structural rather than intrinsic, i.e., in the case of an isotropic solid material with an anisotropic pore structure. In this case the effective stress law involves the solid or grain bulk modulus and two or three moduli of the porous material, for transverse isotropy and orthotropy, respectively. The law reduces, in the case of isotropic response, to that suggested by Geertsma (1957) and by Skempton (1961) and derived analytically by Nur and Byerlee

  18. The effect of acute exercise and psychosocial stress on fine motor skills and testosterone concentration in the saliva of high school students.

    Directory of Open Access Journals (Sweden)

    Mirko Wegner

    Full Text Available Little is known about the influence of different stressors on fine motor skills, the concentration of testosterone (T, and their interaction in adolescents. Therefore, 62 high school students aged 14-15 years were randomly assigned to two experimental groups (exercise, psychosocial stress and a control group. Exercise stress was induced at 65-75% of the maximum heart rate by running for 15 minutes (n = 24. Psychosocial stress was generated by an intelligence test (HAWIK-IV, which was uncontrollable and characterized by social-evaluative-threat to the students (n = 21. The control group followed was part of a regular school lesson with the same duration (n = 28. Saliva was collected after a normal school lesson (pre-test as well as after the intervention/control period (post-test and was analyzed for testosterone. Fine motor skills were assessed pre- and post-intervention using a manual dexterity test (Flower Trail from the Movement Assessment Battery for Children-2. A repeated measure ANCOVA including gender as a covariate revealed a significant group by test interaction, indicating an increase in manual dexterity only for the psychosocial stress group. Correlation analysis of all students shows that the change of testosterone from pre- to post-test was directly linked (r = -.31, p = .01 to the changes in manual dexterity performance. Participants showing high increases in testosterone from pre- to post-test made fewer mistakes in the fine motor skills task. Findings suggest that manual dexterity increases when psychosocial stress is induced and that improvement of manual dexterity performance corresponds with the increase of testosterone.

  19. Effects of Cadmium Stress on Seed Germination, Seedling Growth and Seed Amylase Activities in Rice (Oryza sativa

    Directory of Open Access Journals (Sweden)

    Jun-yu HE

    2008-12-01

    Full Text Available Two rice varieties, Xiushui 110 with high cadmium (Cd tolerance and Xiushui 11 with low Cd tolerance were used to study the effects of Cd stress on seed germination, seedling growth and amylase activities. The low cadmium concentration had little effect on seed germination rate. However, cadmium stress could significantly inhibit plumule and radicle growth, especially for radicle growth. Germination index, vigour index, radicle length and amylase activities of Xiushui 11 decreased more significantly with the increasing cadmium level compared with Xiushui 110. The cadmium content in seedlings of Xiushui 11 was higher than that in Xiushui 110 when the cadmium concentration exceeded 5 μmol/L, which caused lower mitotic index in root tips and amylase activities, and more serious cadmium toxicity in Xiushui 11.

  20. The effects of exogenous proline and osmotic stress on morpho ...

    African Journals Online (AJOL)

    For evaluation of growth parameters of strawberry callus under osmotic stress and exogenous proline, embryonic calli were transferred to Murashige and Skoog (MS) medium containing four sucrose (osmotic stress) treatments including 3, 6, 9 and 12% and various concentrations of exogenous Lproline (0, 2.5, 5 and 10 ...

  1. Effects of Salt Stress on Three Ecologically Distinct Plantago Species.

    Science.gov (United States)

    Al Hassan, Mohamad; Pacurar, Andrea; López-Gresa, María P; Donat-Torres, María P; Llinares, Josep V; Boscaiu, Monica; Vicente, Oscar

    2016-01-01

    Comparative studies on the responses to salt stress of taxonomically related taxa should help to elucidate relevant mechanisms of stress tolerance in plants. We have applied this strategy to three Plantago species adapted to different natural habitats, P. crassifolia and P. coronopus-both halophytes-and P. major, considered as salt-sensitive since it is never found in natural saline habitats. Growth inhibition measurements in controlled salt treatments indicated, however, that P. major is quite resistant to salt stress, although less than its halophytic congeners. The contents of monovalent ions and specific osmolytes were determined in plant leaves after four-week salt treatments. Salt-treated plants of the three taxa accumulated Na+ and Cl- in response to increasing external NaCl concentrations, to a lesser extent in P. major than in the halophytes; the latter species also showed higher ion contents in the non-stressed plants. In the halophytes, K+ concentration decreased at moderate salinity levels, to increase again under high salt conditions, whereas in P. major K+ contents were reduced only above 400 mM NaCl. Sorbitol contents augmented in all plants, roughly in parallel with increasing salinity, but the relative increments and the absolute values reached did not differ much in the three taxa. On the contrary, a strong (relative) accumulation of proline in response to high salt concentrations (600-800 mM NaCl) was observed in the halophytes, but not in P. major. These results indicate that the responses to salt stress triggered specifically in the halophytes, and therefore the most relevant for tolerance in the genus Plantago are: a higher efficiency in the transport of toxic ions to the leaves, the capacity to use inorganic ions as osmotica, even under low salinity conditions, and the activation, in response to very high salt concentrations, of proline accumulation and K+ transport to the leaves of the plants.

  2. Stress and Memory: Behavioral Effects and Neurobiological Mechanisms

    Directory of Open Access Journals (Sweden)

    M. Teresa Pinelo-Nava

    2007-04-01

    Full Text Available Stress is a potent modulator of learning and memory processes. Although there have been a few attempts in the literature to explain the diversity of effects (including facilitating, impairing, and lack of effects described for the impact of stress on memory function according to single classification criterion, they have proved insufficient to explain the whole complexity of effects. Here, we review the literature in the field of stress and memory interactions according to five selected classifying factors (source of stress, stressor duration, stressor intensity, stressor timing with regard to memory phase, and learning type in an attempt to develop an integrative model to understand how stress affects memory function. Summarizing on those conditions in which there was enough information, we conclude that high stress levels, whether intrinsic (triggered by the cognitive challenge or extrinsic (induced by conditions completely unrelated to the cognitive task, tend to facilitate Pavlovian conditioning (in a linear-asymptotic manner, while being deleterious for spatial/explicit information processing (which with regard to intrinsic stress levels follows an inverted U-shape effect. Moreover, after reviewing the literature, we conclude that all selected factors are essential to develop an integrative model that defines the outcome of stress effects in memory processes. In parallel, we provide a brief review of the main neurobiological mechanisms proposed to account for the different effects of stress in memory function. Glucocorticoids were found as a common mediating mechanism for both the facilitating and impairing actions of stress in different memory processes and phases. Among the brain regions implicated, the hippocampus, amygdala, and prefrontal cortex were highlighted as critical for the mediation of stress effects.

  3. Recovery of normal testicular temperature after scrotal heat stress in rams assessed by infrared thermography and its effects on seminal characteristics and testosterone blood serum concentration.

    Science.gov (United States)

    Alves, Maíra Bianchi Rodrigues; Andrade, André Furugen Cesar de; Arruda, Rubens Paes de; Batissaco, Leonardo; Florez-Rodriguez, Shirley Andrea; Oliveira, Bruna Marcele Martins de; Torres, Mariana Andrade; Lançoni, Renata; Ravagnani, Gisele Mouro; Prado Filho, Roberto Romano do; Vellone, Vinícius Silva; Losano, João Diego de Agostini; Franci, Celso Rodrigues; Nichi, Marcílio; Celeghini, Eneiva Carla Carvalho

    2016-08-01

    Reestablishment of testicular normal temperature after testicular heat stress is unknown and its effect varies widely. The aim of this study was to investigate the impact of scrotal insulation (IN) on testicular temperature and its relation to semen quality and testosterone blood serum concentration. For this, 33 rams were used; 17 submitted to IN for 72 hours (using bags involving the testes) and 16 not submitted to IN (control group). The experiment was performed between August and December 2013 in Pirassununga, Brazil (21°56″13″ South/47°28'24″ West). Seminal characteristics, testosterone blood serum concentration, rectal temperature (RT), respiratory frequency, scrotal superficies mean temperature (SSMT), and eye area mean temperature (EAMT) were analyzed 7 days before IN and 21, 35, 49, 63, and 90 days afterward. Scrotal superficies mean temperature and EAMT were measured by thermography camera FLIR T620. Testosterone was evaluated by radioimmunoassay. Analysis of variance was used to determine the main effects of treatment, time, and treatment-by-time interaction using PROC MIXED of SAS software adding command REPEAT. Pearson correlation test was used to verify correlation between SSMT, EAMT, RT, and respiratory frequency. Significant difference was considered when P ≤ 0.05. At the end of IN, SSMT was higher (P blood serum concentration was lesser in insulated rams (P = 0.03). Thus, the difference of 1.12 °C between RT and testicular temperature impacts semen quality and testosterone blood serum concentration. Moreover, this study shows that rams can recover testes temperature efficiently toward IN and that infrared thermography is an efficient tool to identify differences on SSMT. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Hematological and immunological effects of stress of air traffic controllers in northeastern Brazil

    Directory of Open Access Journals (Sweden)

    Valdenilson Ribeiro Ribas

    2011-06-01

    Full Text Available BACKGROUND: Several studies have shown that stress and emotional reactions can affect immune responses in animals and humans. OBJECTIVE: The aim of this study was to evaluate hematological and immunological effects of stress on air traffic controllers. METHODS: Thirty air traffic controllers and 15 aeronautical information service operators were evaluated. The groups were divided as information service operators with 10 years or more of experience (AIS>10 and with less than 10 years in the profession (AIS10 and with less than 10 years in the profession (ATCo10 group presented a significantly lower phagocytosis rate of monocytes at 2:00 p.m. compared to 8:00 a.m. Moreover, the ATCo>10 group presented lower hemoglobin, mean corpuscular hemoglobin concentration, platelet and leukocyte levels, and increased cortisol concentrations at 8:00 a.m. compared to the other groups. Additionally, this group had lower phagocytosis rate of monocytes, and hemoglobin, platelet, leukocyte, basophils and nitric oxide levels at 2:00 p.m. compared to the other groups. CONCLUSION: Stress seems to greatly affect immune responses of air traffic controllers with more than ten years of experience.

  5. Greater physiological and behavioral effects of interrupted stress pattern compared to daily restraint stress in rats.

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    Full Text Available Repeated stress can trigger a range of psychiatric disorders, including anxiety. The propensity to develop abnormal behaviors after repeated stress is related to the severity, frequency and number of stressors. However, the pattern of stress exposure may contribute to the impact of stress. In addition, the anxiogenic nature of repeated stress exposure can be moderated by the degree of coping that occurs, and can be reflected in homotypic habituation to the repeated stress. However, expectations are not clear when a pattern of stress presentation is utilized that diminishes habituation. The purpose of these experiments is to test whether interrupted stress exposure decreases homotypic habituation and leads to greater effects on anxiety-like behavior in adult male rats. We found that repeated interrupted restraint stress resulted in less overall homotypic habituation compared to repeated daily restraint stress. This was demonstrated by greater production of fecal boli and greater corticosterone response to restraint. Furthermore, interrupted restraint stress resulted in a lower body weight and greater adrenal gland weight than daily restraint stress, and greater anxiety-like behavior in the elevated plus maze. Control experiments demonstrated that these effects of the interrupted pattern could not be explained by differences in the total number of stress exposures, differences in the total number of days that the stress periods encompased, nor could it be explained as a result of only the stress exposures after an interruption from stress. These experiments demonstrate that the pattern of stress exposure is a significant determinant of the effects of repeated stress, and that interrupted stress exposure that decreases habituation can have larger effects than a greater number of daily stress exposures. Differences in the pattern of stress exposure are therefore an important factor to consider when predicting the severity of the effects of repeated

  6. Modeling the Effects of Stress: An Approach to Training

    Science.gov (United States)

    Cuper, Taryn

    2010-01-01

    Stress is an integral element of the operational conditions experienced by combat medics. The effects of stress can compromise the performance of combat medics who must reach and treat their comrades under often threatening circumstances. Examples of these effects include tunnel vision, loss of motor control, and diminished hearing, which can result in an inability to perceive further danger, satisfactorily treat the casualty, and communicate with others. While many training programs strive to recreate this stress to aid in the experiential learning process, stress inducement may not always be feasible or desired. In addition, live simulations are not always a practical, convenient, and repeatable method of training. Instead, presenting situational training on a personal computer is proposed as an effective training platform in which the effects of stress can be addressed in a different way. We explore the cognitive and motor effects of stress, as well as the benefits of training for mitigating these effects in real life. While many training applications focus on inducing stress in order to "condition" the stress response, the author explores the possibilities of modeling stress to produce a similar effect. Can presenting modeled effects of stress help prepare or inoculate soldiers for stressful situations in which they must perform at a high level? This paper investigates feasibility of modeling stress and describes the preliminary design considerations of a combat medic training system that utilizes this method of battlefield preparation.

  7. Stress effects on memory : An update and integration

    NARCIS (Netherlands)

    Schwabe, Lars; Joëls, Marian; Roozendaal, Benno; Wolf, Oliver T.; Oitzl, Melly S.

    It is well known that stressful experiences may affect learning and memory processes. Less clear is the exact nature of these stress effects on memory: both enhancing and impairing effects have been reported. These opposite effects may be explained if the different time courses of stress hormone, in

  8. Stress effects on memory: an update and integration

    NARCIS (Netherlands)

    Schwabe, L.; Joëls, M.; Roozendaal, B.; Wolf, O.T.; Oitzl, M.S.

    2012-01-01

    It is well known that stressful experiences may affect learning and memory processes. Less clear is the exact nature of these stress effects on memory: both enhancing and impairing effects have been reported. These opposite effects may be explained if the different time courses of stress hormone, in

  9. Cortisol and ghrelin concentrations following a cold pressor stress test in overweight individuals with and without night eating.

    Science.gov (United States)

    Geliebter, A; Carnell, S; Gluck, M E

    2013-08-01

    To explore appetite-related hormones following stress in overweight individuals, and their relationship with night eating (NE) status. We measured plasma cortisol and ghrelin concentrations, and recorded ratings of stress and hunger in response to a physiological laboratory stressor (cold pressor test, CPT), in overweight women with (n=11; NE) and without (n=17; non-NE) NE. Following the CPT, cortisol (Plevels increased, as did stress and hunger ratings (all Pcortisol (Plevels than non-NE. NE also had greater cortisol area under the curve (AUC) than non-NE (P=0.019), but not when controlling for baseline cortisol levels. Ghrelin baseline and AUC did not differ between groups. NE showed higher AUC stress (Pcortisol, ghrelin, stress and hunger following a laboratory stressor, and there was some evidence for greater increases in cortisol and subjective stress among NE. The greater AUC cortisol level in NE was due to higher baseline levels, but the group difference in stress was in direct response to the stressor. Our results support a role for cortisol and stress in NE.

  10. Antioxidant and neuroprotective effects of Scrophularia striata extract against oxidative stress-induced neurotoxicity.

    Science.gov (United States)

    Azadmehr, Abbas; Oghyanous, Keyvan Alizadeh; Hajiaghaee, Reza; Amirghofran, Zahra; Azadbakht, Mohammad

    2013-11-01

    In this study, the neuroprotective effect of Scrophularia striata Boiss (Scrophulariaceae) extract, a plant growing in northeastern of Iran, against oxidative stress-induced neurocytotoxicity in PC12 was evaluated. The PC12 cell line pretreated with different concentrations (10, 50, 100, and 200 μg/ml) of the extract and then treated with H2O2 to induce oxidative stress and neurotoxicity. Survival of the cells, reactive oxygen species (ROS) generation, and apoptosis were measured using MTT assay, fluorescent probe 2',7'-dichlorofluorescein diacetate, and annexin V/propidium iodide, respectively. Moreover, the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) was used to evaluate the antioxidant capacity of the plant extract. Phytochemical assay by thin layer chromatography showed that the main components, including phenolic compounds, phenyl propanoids and flavonoids, were presented in the S. striata extract. The extract in concentrations of 50-200 μg/ml protected PC12 cells from H2O2-induced toxicity. The survival of the cells at concentration of 200 μg/ml was 64 % compared to that of H2O2 alone-treated cells (48 %) (p extract also dose-dependently reduced intracellular ROS production (p extract showed antioxidative effects and decreased apoptotic cells. Collectively, these findings indicated the ability of S. striata to decrease ROS generation and cell apoptosis and also suggest the presence of the neuroprotective agents in this plant.

  11. Effects of Pluronic F-68 on Tetrahymena cells: protection against chemical and physical stress and prolongation of survival under toxic conditions

    DEFF Research Database (Denmark)

    Hellung-Larsen, P; Assaad, F; Pankratova, Stanislava

    2000-01-01

    exposed to hyperthermia (43 degrees C). The cellular survival is increased at reduced temperatures (e.g. 4 degrees C instead of 36 degrees C) and at increased cellular concentrations (e.g. 100 cells ml(-1) instead of 25 or 10 cells ml(-1)). There is no effect of pre-incubation with Pluronic......The effects of the non-ionic surfactant Pluronic F-68 (0.01% w/v) on Tetrahymena cells have been studied. A marked protection against chemical and physical stress was observed. The chemical stress effects were studied in cells suspended in buffer (starvation) or in buffers with added ingredients....... The protective effect of Pluronic towards Tetrahymena is observed for concentrations in the range from 0.001 to 0.1% w/v....

  12. Possible GABAergic modulation in the protective effect of zolpidem in acute hypoxic stress-induced behavior alterations and oxidative damage.

    Science.gov (United States)

    Kumar, Anil; Goyal, Richa

    2008-03-01

    Hypoxia is an environmental stressor that is known to elicit alterations in both the autonomic nervous system and endocrine functions. The free radical or oxidative stress theory holds that oxidative reactions are mainly underlying neurodegenerative disorders. In fact among complex metabolic reactions occurring during hypoxia, many could be related to the formation of oxygen derived free radicals, causing a wide spectrum of cell damage. In present study, we investigated possible involvement of GABAergic mechanism in the protective effect of zolpidem against acute hypoxia-induced behavioral modification and biochemical alterations in mice. Mice were subjected to acute hypoxic stress for a period of 2 h. Acute hypoxic stress for 2 h caused significant impairment in locomotor activity, anxiety-like behavior, and antinocioceptive effect in mice. Biochemical analysis revealed a significant increased malondialdehyde, nitrite concentrations and depleted reduced glutathione and catalase levels. Pretreatment with zolpidem (5 and 10 mg/kg, i.p.) significantly improved locomotor activity, anti-anxiety effect, reduced tail flick latency and attenuated oxidative damage (reduced malondialdehyde, nitrite concentration, and restoration of reduced glutathione and catalase levels) as compared to stressed control (hypoxia) (P zolpidem (5 mg/kg) was blocked significantly by picrotoxin (1.0 mg/kg) or flumazenil (2 mg/kg) and potentiated by muscimol (0.05 mg/kg) in hypoxic animals (P zolpidem (5 mg/kg) per se (P zolpidem against hypoxic stress.

  13. Stress effects on mood, HPA axis, and autonomic response: comparison of three psychosocial stress paradigms.

    Directory of Open Access Journals (Sweden)

    Grace E Giles

    Full Text Available Extensive experimental psychology research has attempted to parse the complex relationship between psychosocial stress, mood, cognitive performance, and physiological changes. To do so, it is necessary to have effective, validated methods to experimentally induce psychosocial stress. The Trier Social Stress Test (TSST is the most commonly used method of experimentally inducing psychosocial stress, but it is resource intensive. Less resource intense psychosocial stress tasks include the Socially Evaluative Cold Pressor Task (SECPT and a computerized mental arithmetic task (MAT. These tasks effectively produce a physiological and psychological stress response and have the benefits of requiring fewer experimenters and affording data collection from multiple participants simultaneously. The objective of this study was to compare the magnitude and duration of these three experimental psychosocial stress induction paradigms. On each of four separate days, participants completed either a control non-stressful task or one of the three experimental stressors: the TSST, SECPT, or MAT. We measured mood, working memory performance, salivary cortisol and alpha-amylase (AA, and heart rate. The TSST and SECPT exerted the most robust effects on mood and physiological measures. TSST effects were generally evident immediately post-stress as well as 10- and 20-minutes after stress cessation, whereas SECPT effects were generally limited to the duration of the stressor. The stress duration is a key determinant when planning a study that utilizes an experimental stressor, as researchers may be interested in collecting dependent measures prior to stress cessation. In this way, the TSST would allow the investigator a longer window to administer tasks of interest.

  14. THE COMBINED EFFECTS OF STRESS CONCENTRATION AND TENSILE STRESSES FROM AUTOFRETTAGE ON THE LIFE OF PRESSURE VESSELS

    Science.gov (United States)

    2017-02-22

    information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing ... hydraulically or mechanically overstrained in order to impart favorable near bore residual compressive hoop stresses in an attempt to enhance fatigue life. As a...detrimental. In the early stages of development of each system, multiple full size vessels are hydraulically fatigue tested and a safe life is

  15. Dynamics of a Lüders Band and Destruction of an Aluminum-Magnesium Alloy, Initiated by a Stress Concentrator

    Science.gov (United States)

    Shibkov, A. A.; Zheltov, M. A.; Gasanov, M. F.; Zolotov, A. E.

    2018-02-01

    Spatio-temporal localization of deformation and the rupture of the aluminum-magnesium AlMg6 alloy, initiated by a geometrical stress concentrator, are studied in situ by video recording at a speed of 500 to 20000 frames/s. It is established that a stress concentrator in the form of a small notch with a depth about 1% of the width of a flat specimen is an attractor of bands of macrolocalized plastic deformation, starting from a Lüders band and ending with the start of the main crack. The key role of intersecting deformation macrobands in the development of the main crack is revealed. Possible micromechanisms of viscous destruction associated with the dynamics of the intersection of deformation bands are discussed.

  16. The effect of stress on men's food selection.

    Science.gov (United States)

    Zellner, Debra A; Saito, Shin; Gonzalez, Johanie

    2007-11-01

    This study investigates the effect of stress on food choice among men. Two groups of men were given either solvable (no-stress) or unsolvable (stress) anagrams to solve. Four bowls of snack foods-two healthy (peanuts and grapes) and two unhealthy (potato chips and M&M chocolate candies)-were available and subjects were invited to snack on them. Men in the no-stress group ate significantly more of the unhealthy foods than did men in the stress group. This finding is quite different from that found with women [Zellner et al. (2006). Food selection changes under stress. Physiology & Behavior, 87, 789-793]. Women tended to eat more grapes when not stressed than when stressed and more M&Ms when stressed than when not stressed. Thus, the effect of stress level on food choice is different for men and women.

  17. Straightened cervical lordosis causes stress concentration: a finite element model study

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Wei; Shi, Shiyuan; Fei, Jun; Wang, Yifan; Chen, Chunyue [Hangzhou Red Cross Hospital, Hangzhou, Zhejiang, (China); Liao, Shenhui [School of Information Science and Engineering, Central South University, Changsha, Hunan (China)

    2013-03-15

    In this study, we propose a finite element analysis of the complete cervical spine with straightened and normal physiological curvature by using a specially designed modelling system. An accurate finite element model is established to recommend plausible approaches to treatment of cervical spondylosis through the finite element analysis results. There are few reports of biomechanics influence of the straightened cervical curve. It is difficult to measure internal responses of cervical spine directly. However, the finite element method has been reported to have the capability to quantify both external and internal responses to mechanical loading, such as the strain and stress distribution of spinal components. We choose a subject with a straightened cervical spine from whom to collect the CT scan data, which formed the basis of the finite element analysis. By using a specially designed modelling system, a high quality finite element model of the complete cervical spine with straightened curvature was generated, which was then mapped to reconstruct a normal physiological curvature model by a volumetric mesh deformation method based on discrete differential properties. Then, the same boundary conditions were applied to do a comparison. The result demonstrated that the active movement range of straightened cervical spine decreased by 24–33 %, but the stress increased by 5–95 %. The stress was concentrated at the facet joint cartilage, uncovertebral joint and the disk. The results suggest that cervical lordosis may have a direct impact on cervical spondylosis treatment. These results may be useful for clinical treatment of cervical spondylosis with straightened curvature.

  18. Straightened cervical lordosis causes stress concentration: a finite element model study

    International Nuclear Information System (INIS)

    Wei, Wei; Shi, Shiyuan; Fei, Jun; Wang, Yifan; Chen, Chunyue; Liao, Shenhui

    2013-01-01

    In this study, we propose a finite element analysis of the complete cervical spine with straightened and normal physiological curvature by using a specially designed modelling system. An accurate finite element model is established to recommend plausible approaches to treatment of cervical spondylosis through the finite element analysis results. There are few reports of biomechanics influence of the straightened cervical curve. It is difficult to measure internal responses of cervical spine directly. However, the finite element method has been reported to have the capability to quantify both external and internal responses to mechanical loading, such as the strain and stress distribution of spinal components. We choose a subject with a straightened cervical spine from whom to collect the CT scan data, which formed the basis of the finite element analysis. By using a specially designed modelling system, a high quality finite element model of the complete cervical spine with straightened curvature was generated, which was then mapped to reconstruct a normal physiological curvature model by a volumetric mesh deformation method based on discrete differential properties. Then, the same boundary conditions were applied to do a comparison. The result demonstrated that the active movement range of straightened cervical spine decreased by 24–33 %, but the stress increased by 5–95 %. The stress was concentrated at the facet joint cartilage, uncovertebral joint and the disk. The results suggest that cervical lordosis may have a direct impact on cervical spondylosis treatment. These results may be useful for clinical treatment of cervical spondylosis with straightened curvature.

  19. Isoprene in poplar emissions: effects on new particle formation and OH concentrations

    Science.gov (United States)

    Kiendler-Scharr, A.; Andres, S.; Bachner, M.; Behnke, K.; Broch, S.; Hofzumahaus, A.; Holland, F.; Kleist, E.; Mentel, T. F.; Rubach, F.; Springer, M.; Steitz, B.; Tillmann, R.; Wahner, A.; Schnitzler, J.-P.; Wildt, J.

    2012-01-01

    Stress-induced volatile organic compound (VOC) emissions from transgenic Grey poplar modified in isoprene emission potential were used for the investigation of photochemical secondary organic aerosol (SOA) formation. In poplar, acute ozone stress induces the emission of a wide array of VOCs dominated by sesquiterpenes and aromatic VOCs. Constitutive light-dependent emission of isoprene ranged between 66 nmol m-2 s-1 in non-transgenic controls (wild type WT) and nearly zero (plants (line RA22), respectively. Nucleation rates of up to 3600 cm-3 s-1 were observed in our experiments. In the presence of isoprene new particle formation was suppressed compared to non-isoprene containing VOC mixtures. Compared to isoprene/monoterpene systems emitted from other plants the suppression of nucleation by isoprene was less effective for the VOC mixture emitted from stressed poplar. This is explained by the observed high efficiency of new particle formation for emissions from stressed poplar. Direct measurements of OH in the reaction chamber revealed that the steady state concentration of OH is lower in the presence of isoprene than in the absence of isoprene, supporting the hypothesis that isoprenes' suppressing effect on nucleation is related to radical chemistry. In order to test whether isoprene contributes to SOA mass formation, fully deuterated isoprene (C5D8) was added to the stress-induced emission profile of an isoprene free poplar mutant. Mass spectral analysis showed that, despite the isoprene-induced suppression of particle formation, fractions of deuterated isoprene were incorporated into the SOA. A fractional mass yield of 2.3% of isoprene was observed. Future emission changes due to land use and climate change may therefore affect both gas phase oxidation capacity and new particle number formation.

  20. Oxidative stress mediated toxicity of TiO2 nanoparticles after a concentration and time dependent exposure of the aquatic macrophyte Hydrilla verticillata.

    Science.gov (United States)

    Spengler, Annette; Wanninger, Lena; Pflugmacher, Stephan

    2017-09-01

    The present study focused on oxidative stress effects in the aquatic macrophyte Hydrilla verticillata after exposure to titanium dioxide nanoparticles (TiO 2 -NPs). Experiments were conducted with different TiO 2 -NPs and concentrations (0.1 mg/L and 10 mg/L) in a time-dependent manner (0 h, 24 h, 48 h, 96 h, 168 h). To assess various levels of the oxidative stress response in H. verticillata, the level of hydrogen peroxide (H 2 O 2 ), the ratio of reduced to oxidized glutathione (GSH/GSSG), and activities of the antioxidative enzymes catalase (CAT) and glutathione reductase (GR) were evaluated. Study results imply oxidative stress effects after TiO 2 -NP exposure as adaptations in plant metabolism became apparent to counteract increased ROS formation. All TiO 2 -NPs caused elevated activities of the enzymes CAT and GR. Moreover, decreased ratios of GSH/GSSG indicated an activation of GSH-dependent pathways counteracting ROS formation. Plants exposed to a bulk-sized control revealed a size-dependent influence on the antioxidative stress response. As H 2 O 2 level increases were solely detected after exposure to 10 mg/L TiO 2 -NPs and nano-exposed plants showed normalization in its antioxidative stress response after 168h of exposure, it can be suggested that macrophytes are able to cope with currently predicted low-level exposures to TiO 2 -NPs. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Effect of cycocel on photosynthetic activity and essential oil of fennel (Foeniculum vulgare Mill. under drought stress

    Directory of Open Access Journals (Sweden)

    Fatemeh Nouri

    2014-12-01

    Full Text Available Drought stress is one of the most important and most common environmental stresses that limit plant growth. Photosynthesis is the main determinant of plant growth and its retention ability under environmental stress condition is important for preservation of growth stability. To study the effect of spraying CCC on photosynthesis activity and essential oil content on 'Foeniculum vulgare', an experiment was done in split plot design based on complete block with four replications in research field of University of Zanjan in 2011. Levels of drought stress included, control, soft stress (when 30% of available water was out of soil, severe stress (when 90% of available water was out of soil, and three concentration of CCC 0, 1500 and 3000 mg/L. The results showed that between rates foliar application on physiologic characteristics as photosynthesis rate, transpiration severity, RWC and TΔ intercellular (Ci, stomata conductivity, mesophyll conductivity and essential oil content was significant. By spraying 3000 mg/L CCC, balanced the plant position against drought stress and could reduce negative effect. Foliar application of CCC caused significant increase in photosynthesis rate, mesophyll conductivity and significant decrease stomata conductivity, transpiration severity under drought stress and could increase essential oil content under soft stress. In this study, foliar application of CCC to content 3000 mg/L had the highest effect on this characters.

  2. Oxidative stress suppresses the cellular bioenergetic effect of the 3-mercaptopyruvate sulfurtransferase/hydrogen sulfide pathway

    Energy Technology Data Exchange (ETDEWEB)

    Módis, Katalin [Department of Anesthesiology, University of Texas Medical Branch and Shriners Burns Hospital for Children, Galveston, TX (United States); Asimakopoulou, Antonia [Laboratory of Molecular Pharmacology, Department of Pharmacy, University of Patras, Patras (Greece); Coletta, Ciro [Department of Anesthesiology, University of Texas Medical Branch and Shriners Burns Hospital for Children, Galveston, TX (United States); Papapetropoulos, Andreas [Department of Anesthesiology, University of Texas Medical Branch and Shriners Burns Hospital for Children, Galveston, TX (United States); Laboratory of Molecular Pharmacology, Department of Pharmacy, University of Patras, Patras (Greece); Szabo, Csaba, E-mail: szabocsaba@aol.com [Department of Anesthesiology, University of Texas Medical Branch and Shriners Burns Hospital for Children, Galveston, TX (United States)

    2013-04-19

    Highlights: •Oxidative stress impairs 3-MST-derived H{sub 2}S production in isolated enzyme and in isolated mitochondria. •This impairs the stimulatory bioenergetic effects of H{sub 2}S in hepatocytes. •This has implications for the pathophysiology of diseases with oxidative stress. -- Abstract: Recent data show that lower concentrations of hydrogen sulfide (H{sub 2}S), as well as endogenous, intramitochondrial production of H{sub 2}S by the 3-mercaptopyruvate (3-MP)/3-mercaptopyruvate sulfurtransferase (3-MST) pathway serves as an electron donor and inorganic source of energy to support mitochondrial electron transport and ATP generation in mammalian cells by donating electrons to Complex II. The aim of our study was to investigate the role of oxidative stress on the activity of the 3-MP/3-MST/H{sub 2}S pathway in vitro. Hydrogen peroxide (H{sub 2}O{sub 2}, 100–500 μM) caused a concentration-dependent decrease in the activity of recombinant mouse 3-MST enzyme. In mitochondria isolated from murine hepatoma cells, H{sub 2}O{sub 2} (50–500 μM) caused a concentration-dependent decrease in production of H{sub 2}S from 3-MP. In cultured murine hepatoma cells H{sub 2}O{sub 2}, (3–100 μM), did not result in overall cytotoxicity, but caused a partial decrease in basal oxygen consumption and respiratory reserve rapacity. The positive bioenergetic effect of 3-MP (100–300 nM) was completely abolished by pre-treatment of the cells with H{sub 2}O{sub 2} (50 μM). The current findings demonstrate that oxidative stress inhibits 3-MST activity and interferes with the positive bioenergetic role of the 3-MP/3-MST/H{sub 2}S pathway. These findings may have implications for the pathophysiology of various conditions associated with increased oxidative stress, such as various forms of critical illness, cardiovascular diseases, diabetes or physiological aging.

  3. Effect of Thickness Stress in Stretch-Bending

    NARCIS (Netherlands)

    van den Boogaard, Antonius H.; Emmens, W.C.; Huetink, Han; Barlat, F; Moon, Y.H.; Lee, M.G.

    2010-01-01

    In any situation where a strip is pulled over a curved tool, locally a contact stress acts on the strip in thickness direction. This contact stress changes the stress state in the material, which will influence the deformation. One effect is that the yield stress in the plane of the strip is

  4. The concentration of fear: mice's behavioural and physiological stress responses to different degrees of predation risk

    Science.gov (United States)

    Sánchez-González, Beatriz; Planillo, Aimara; Navarro-Castilla, Álvaro; Barja, Isabel

    2018-02-01

    Predation is an unavoidable and dangerous fact in the lifetime of prey animals and some sign of the proximity of a predator may be enough to trigger a response in the prey. We investigated whether different degrees of predation risk by red foxes ( Vulpes vulpes) evoke behavioural and physiological stress responses in wood mice ( Apodemus sylvaticus) . We examined the variation in mice responses due to individual factors (sex and reproductive status) and related them to the concentration of the volatile compounds from fox faeces over time. In our experiment, we introduced predation cues into four plots, each subjected to a different concentration treatment (0, 10, 50 and 100% concentration of fresh faeces of red fox), based on the following outline: initial odourless phase 0, phase1 in which predation treatment was renewed daily, and phase 2 in which we renewed the treatment only on the first day. Wood mice were live trapped during all three phases and the physiological response was measured non-invasively by analysing faecal corticosterone metabolites (FCM) in freshly collected faeces. Data were analysed by Generalized Linear Mixed Models. Overall, males were trapped less often than females, and reproductively active individuals from both sexes avoided traps more than non-reproductively active individuals, especially in medium- and high- concentration plots. Variations in FCM concentrations were explained by plot, the interaction between plot and treatment phase, and the interaction between the treatment phase and the reproductive status. During phase 1, we detected a significant rise in FCM levels that increased with predator faecal odour concentration. Additionally, reproductively active individuals showed a strong physiological response during both phases 1 and 2 in all plots, except the control plot. Our results indicated that wood mice are able to discriminate different degrees of predation risk, which allows them to trigger gradual changes in their

  5. An Investigation of the Combined Effect of Stress, Fatigue and Workload on Human Performance: Position Paper

    Science.gov (United States)

    Mock, Jessica

    2005-01-01

    Stress, fatigue, and workload affect worker performance. NSF reported that 61% of respondents state losing concentration at work while 79% occasionally or frequently made errors as a result of being fatigued. Shift work, altered work schedules, long hours of continuous wakefulness, and sleep loss can create sleep and circadian disruptions that degrade waking fundions causing stress and fatigue. Review of the literature has proven void of information that links the combined effects of fatigue, stress, and workload to human performance. This paper will address which occupational factors within stress, fatigue, and workload were identified as occupational contributors to performance changes. The results of this research will be apglied to underlying models and algorithms that will help predict performance changes in control room operators.

  6. Effect of elasticity on stress distribution in CAD/CAM dental crowns: Glass ceramic vs. polymer-matrix composite.

    Science.gov (United States)

    Duan, Yuanyuan; Griggs, Jason A

    2015-06-01

    Further investigations are required to evaluate the mechanical behaviour of newly developed polymer-matrix composite (PMC) blocks for computer-aided design/computer-aided manufacturing (CAD/CAM) applications. The purpose of this study was to investigate the effect of elasticity on the stress distribution in dental crowns made of glass-ceramic and PMC materials using finite element (FE) analysis. Elastic constants of two materials were determined by ultrasonic pulse velocity using an acoustic thickness gauge. Three-dimensional solid models of a full-coverage dental crown on a first mandibular molar were generated based on X-ray micro-CT scanning images. A variety of load case-material property combinations were simulated and conducted using FE analysis. The first principal stress distribution in the crown and luting agent was plotted and analyzed. The glass-ceramic crown had stress concentrations on the occlusal surface surrounding the area of loading and the cemented surface underneath the area of loading, while the PMC crown had only stress concentration on the occlusal surface. The PMC crown had lower maximum stress than the glass-ceramic crown in all load cases, but this difference was not substantial when the loading had a lateral component. Eccentric loading did not substantially increase the maximum stress in the prosthesis. Both materials are resistant to fracture with physiological occlusal load. The PMC crown had lower maximum stress than the glass-ceramic crown, but the effect of a lateral loading component was more pronounced for a PMC crown than for a glass-ceramic crown. Knowledge of the stress distribution in dental crowns with low modulus of elasticity will aid clinicians in planning treatments that include such restorations. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Work-related social support modulates effects of early life stress on limbic reactivity during stress.

    Science.gov (United States)

    Leicht-Deobald, Ulrich; Bruch, Heike; Bönke, Luisa; Stevense, Amie; Fan, Yan; Bajbouj, Malek; Grimm, Simone

    2017-12-15

    Early life stress (ELS) affects stress- reactivity via limbic brain regions implicated such as hippocampus and amygdala. Social support is a major protective factor against ELS effects, while subjects with ELS experience reportedly perceive less of it in their daily life. The workplace, where most adults spend a substantial amount of time in their daily lives, might serve as a major resource for social support. Since previous data demonstrated that social support attenuates stress reactivity, we here used a psychosocial stress task to test the hypothesis that work-related social support modulates the effects of ELS. Results show decreased amygdala reactivity during stress in ELS subjects who report high levels of work- related social support, thereby indicating a signature for reduced stress reactivity. However, this effect was only observable on the neural, but not on the behavioral level, since social support had no buffering effect regarding the subjective experience of stress in daily life as well as regarding feelings of uncontrollability induced by the stress task. Accordingly, our data suggest that subjects with ELS experiences might benefit from interventions targeted at lowering their subjective stress levels by helping them to better perceive the availability of social support in their daily lives.

  8. Short communication: Effect of maternal heat stress in late gestation on blood hormones and metabolites of newborn calves.

    Science.gov (United States)

    Guo, J-R; Monteiro, A P A; Weng, X-S; Ahmed, B M; Laporta, J; Hayen, M J; Dahl, G E; Bernard, J K; Tao, S

    2016-08-01

    Maternal heat stress alters immune function of the offspring, as well as metabolism and future lactational performance, but its effect on the hormonal and metabolic responses of the neonate immediately after birth is still not clear. The objective of this study was to investigate the blood profiles of hormones and metabolites of calves born to cows that were cooled (CL) or heat-stressed (HS) during the dry period. Within 2 h after birth, but before colostrum feeding, blood samples were collected from calves [18 bulls (HS: n=10; CL: n=8) and 20 heifers (HS: n=10; CL: n=10)] born to CL or HS dry cows, and hematocrit and plasma concentrations of total protein, prolactin, insulin-like growth factor-I, insulin, glucose, nonesterified fatty acid, and β-hydroxybutyrate were measured. Compared with CL, HS calves had lower hematocrit and tended to have lower plasma concentrations of insulin, prolactin, and insulin-like growth factor-I. However, maternal heat stress had no effect on plasma levels of total protein, glucose, fatty acid, and β-hydroxybutyrate immediately after birth. These results suggest that maternal heat stress desensitizes a calf's stress response and alters the fetal development by reducing the secretion of insulin-like growth factor-I, prolactin, and insulin. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  9. Impact of chronic maternal stress during early gestation on maternal-fetal stress transfer and fetal stress sensitivity in sheep.

    Science.gov (United States)

    Dreiling, Michelle; Schiffner, Rene; Bischoff, Sabine; Rupprecht, Sven; Kroegel, Nasim; Schubert, Harald; Witte, Otto W; Schwab, Matthias; Rakers, Florian

    2018-01-01

    Acute stress-induced reduction of uterine blood flow (UBF) is an indirect mechanism of maternal-fetal stress transfer during late gestation. Effects of chronic psychosocial maternal stress (CMS) during early gestation, as may be experienced by many working women, on this stress signaling mechanism are unclear. We hypothesized that CMS in sheep during early gestation augments later acute stress-induced decreases of UBF, and aggravates the fetal hormonal, cardiovascular, and metabolic stress responses during later development. Six pregnant ewes underwent repeated isolation stress (CMS) between 30 and 100 days of gestation (dGA, term: 150 dGA) and seven pregnant ewes served as controls. At 110 dGA, ewes were chronically instrumented and underwent acute isolation stress. The acute stress decreased UBF by 19% in both the CMS and control groups (p stress-induced cortisol and norepinephrine concentrations indicating a hyperactive hypothalamus-pituitary-adrenal (HPA)-axis and sympathetic-adrenal-medullary system. Increased fetal norepinephrine is endogenous as maternal catecholamines do not cross the placenta. Cortisol in the control but not in the CMS fetuses was correlated with maternal cortisol blood concentrations; these findings indicate: (1) no increased maternal-fetal cortisol transfer with CMS, (2) cortisol production in CMS fetuses when the HPA-axis is normally inactive, due to early maturation of the fetal HPA-axis. CMS fetuses were better oxygenated, without shift towards acidosis compared to the controls, potentially reflecting adaptation to repeated stress. Hence, CMS enhances maternal-fetal stress transfer by prolonged reduction in UBF and increased fetal HPA responsiveness.

  10. Bifenthrin-induced oxidative stress in human erythrocytes in vitro and protective effect of selected flavonols.

    Science.gov (United States)

    Sadowska-Woda, Izabela; Popowicz, Diana; Karowicz-Bilińska, Agata

    2010-03-01

    Bifenthrin is a synthetic pyrethroid with a broad spectrum of insecticidal and acaricidal activity used to control wide range of insect pests in a variety of applications. This investigation was designed to examine (1) bifenthrin as an inducer of oxidative stress in human erythrocytes in vitro through effects on catalase (CAT) and superoxide dismutase (SOD) activities, and (2) the role of the flavonoids quercetin (Q, 40 and 80microM) and rutin (R, 80microM) in alleviating the effects of bifenthrin. Erythrocytes were divided into portions. The first portion was incubated for 4h at 37 degrees C with different concentrations (0, 42.2, 211, 1055ppm) of bifenthrin. The other portions were preincubated with Q or R for 30min, followed incubation with bifenthrin for 4h. The influence of solvent (ethanol) was also checked on the parameters studied. Malondialdehyde (MDA) concentrations, CAT and SOD activities were measured in all treatment portions of erythrocytes. Our results demonstrated that bifenthrin-induced oxidative stress causes enhanced lipid peroxidation and decreased antioxidative enzyme activities in human peripheral blood. R pretreated erythrocytes were protected against the increase of MDA induced by bifenthrin. Q (80microM) and R pretreated erythrocytes were protected against the inhibition of CAT activity induced by bifenthrin. The protective action against the inhibition of SOD activity of Q was greater than that of R at the same concentration. These results suggest that Q and R may play a role in reducing bifenthrin-induced oxidative stress in vitro. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

  11. Photoelastic investigation of the stresses in mitred bent-cylinders under bending, 2

    International Nuclear Information System (INIS)

    Sawa, Yoshiaki

    1984-01-01

    The states of stress distribution in mitred bend subjected to inplane uniform bending moment have been studied systematically by means of photoelastic stress freezing method. The relations between the stress concentration factor of fiber stress σsub(l) and of hoop stress σsub(theta) near the bent part and the angle of mitred bend are thoroughly investigated. The effects of fillet radius of the bent-part and wall thickness on the stress concentration factors are also discussed. (author)

  12. Pre-slaughter stress and pork quality

    Science.gov (United States)

    Stajković, S.; Teodorović, V.; Baltić, M.; Karabasil, N.

    2017-09-01

    Stress is an inevitable consequence of handling of animals for slaughter. Stress conditions during transport, lairage and at slaughter induce undesirable effects on the end quality of meat such as pale, soft, exudative meat and dark firm dry meat. Hence, it is very important to define appropriate parameters for objective assessment of level of stress. Attempts to define measures of stress have been difficult and no physiological parameter has been successfully used to evaluate stress situations. One physiological change in swine associated with animal handling stress and with pork quality is an increase in blood lactate concentration. Plasma cortisol was thought to be an appropriate indicator of stress, but the concentration was not consistently changed by different stressors. Therefore, finding alternative parameters reacting to stressors, such as acute phase proteins, would be of great value for the objective evaluation of level of stress and meat quality. As the stress during pre-slaughter handling is unavoidable, the final goal is to improve transport and slaughter conditions for the animal and, as a consequence, meat quality and animal welfare.

  13. Effect of modest caloric restriction on oxidative stress in women, a randomized trial.

    Science.gov (United States)

    Buchowski, Maciej S; Hongu, Nobuko; Acra, Sari; Wang, Li; Warolin, Joshua; Roberts, L Jackson

    2012-01-01

    It is not established to what extent caloric intake must be reduced to lower oxidative stress in humans. The aim of this study was to determine the effect of short-term, moderate caloric restriction on markers of oxidative stress and inflammation in overweight and obese premenopausal women. Randomized trial comparison of 25% caloric restriction (CR) or control diet in 40 overweight or obese women (body mass index 32±5.8 kg/m(2)) observed for 28 days and followed for the next 90 days. Weight, anthropometry, validated markers of oxidative stress (F(2)-isoprostane) and inflammation (C-reactive protein), adipokines, hormones, lipids, interleukins, and blood pressure were assessed at baseline, during the intervention, and at follow-up. Baseline median F(2)-isoprostane concentration (57.0, IQR = 40.5-79.5) in the CR group was 1.75-fold above average range for normal weight women (32.5 pg/ml). After starting of the caloric restriction diet, F(2)-isoprostane levels fell rapidly in the CR group, reaching statistical difference from the control group by day 5 (median 33.5, IQR = 26.0-48.0, Prestriction diet. Three months after resuming a habitual diet, concentrations of F(2)-isoprostane returned to baseline elevated levels in ∼80% of the women. Oxidative stress can be rapidly reduced and sustained through a modest reduction in caloric intake suggesting potential health benefits in overweight and obese women. Clinicaltrials.gov NCT00808275.

  14. Effects of stress typicality during speeded grammatical classification.

    Science.gov (United States)

    Arciuli, Joanne; Cupples, Linda

    2003-01-01

    The experiments reported here were designed to investigate the influence of stress typicality during speeded grammatical classification of disyllabic English words by native and non-native speakers. Trochaic nouns and iambic gram verbs were considered to be typically stressed, whereas iambic nouns and trochaic verbs were considered to be atypically stressed. Experiments 1a and 2a showed that while native speakers classified typically stressed words individual more quickly and more accurately than atypically stressed words during differences reading, there were no overall effects during classification of spoken stimuli. However, a subgroup of native speakers with high error rates did show a significant effect during classification of spoken stimuli. Experiments 1b and 2b showed that non-native speakers classified typically stressed words more quickly and more accurately than atypically stressed words during reading. Typically stressed words were classified more accurately than atypically stressed words when the stimuli were spoken. Importantly, there was a significant relationship between error rates, vocabulary size and the size of the stress typicality effect in each experiment. We conclude that participants use information about lexical stress to help them distinguish between disyllabic nouns and verbs during speeded grammatical classification. This is especially so for individuals with a limited vocabulary who lack other knowledge (e.g., semantic knowledge) about the differences between these grammatical categories.

  15. Effects of the implant design on peri-implant bone stress and abutment micromovement: three-dimensional finite element analysis of original computer-aided design models.

    Science.gov (United States)

    Yamanishi, Yasufumi; Yamaguchi, Satoshi; Imazato, Satoshi; Nakano, Tamaki; Yatani, Hirofumi

    2014-09-01

    Occlusal overloading causes peri-implant bone resorption. Previous studies examined stress distribution in alveolar bone around commercial implants using three-dimensional (3D) finite element analysis. However, the commercial implants contained some different designs. The purpose of this study is to reveal the effect of the target design on peri-implant bone stress and abutment micromovement. Six 3D implant models were created for different implant-abutment joints: 1) internal joint model (IM); 2) external joint model (EM); 3) straight abutment (SA) shape; 4) tapered abutment (TA) shapes; 5) platform switching (PS) in the IM; and 6) modified TA neck design (reverse conical neck [RN]). A static load of 100 N was applied to the basal ridge surface of the abutment at a 45-degree oblique angle to the long axis of the implant. Both stress distribution in peri-implant bone and abutment micromovement in the SA and TA models were analyzed. Compressive stress concentrated on labial cortical bone and tensile stress on the palatal side in the EM and on the labial side in the IM. There was no difference in maximum principal stress distribution for SA and TA models. Tensile stress concentration was not apparent on labial cortical bone in the PS model (versus IM). Maximum principal stress concentrated more on peri-implant bone in the RN than in the TA model. The TA model exhibited less abutment micromovement than the SA model. This study reveals the effects of the design of specific components on peri-implant bone stress and abutment displacement after implant-supported single restoration in the anterior maxilla.

  16. Effect of Drying Temperature on Rosmarinic Acid and Sinensetin Concentration in Orthosiphon stamineus Herbal Leaves

    Science.gov (United States)

    Abdullah, Sriyana; Razak Shaari, Abdul; Hajar Rukunudin, Ibni; Syarhabil Ahmad, Muhammad

    2018-03-01

    The objective of this work was to investigate the effects of drying temperature on the concentration of O rthosiphon stamineus biomarker compounds which were rosmarinic acid (RA) and sinensetin (SEN). The thin layer drying approach was used to dry O. stamineus leaves at various temperatures of 30, 40 and 50°C using a laboratory scale hot air dryer. The dried leaves were then extracted using 60% aqueous methanol prior to quantification. The RA and SEN concentrations in the dried leaves extracts were quantified by the high performance liquid chromatography. The concentration of RA for the dried leaves at 30 and 40°C were higher as compared to that of the fresh leaves. This may due to the response of the plant cells to abiotic stress. The concentration of RA also showed a significant reduction when the temperature was increased to 50°C. In contrast, the SEN concentration in O. stamineus dried leaf extract was lower than that of the fresh samples. The concentrations of SEN depicted insignificant effects by drying at 30 and 50°C, and the highest value was obtained in the samples dried at 40°C. Results showed that the drying process was found to affect the concentration of both compounds; therefore suitable drying conditions should be adopted to enhance the medicinal values of the plant species.

  17. Pro-oxidant effects in the brain of rats concurrently exposed to uranium and stress

    International Nuclear Information System (INIS)

    Linares, Victoria; Sanchez, Domenec J.; Belles, Montserrat; Albina, Luisa; Gomez, Mercedes; Domingo, Jose L.

    2007-01-01

    Metal toxicity may be associated with increased rates of reactive oxygen species (ROS) generation within the central nervous system (CNS). Although the kidney is the main target organ for uranium (U) toxicity, this metal can also accumulate in brain. In this study, we investigated the modifications on endogenous antioxidant capacity and oxidative damage in several areas of the brain of U-exposed rats. Eight groups of adult male rats received uranyl acetate dihydrate (UAD) in the drinking water at 0, 10, 20, and 40 mg/kg/day for 3 months. Animals in four groups were concurrently subjected to restraint stress during 2 h/day throughout the study. At the end of the experimental period, cortex, hippocampus and cerebellum were removed and processed to examine the following stress markers: reduced glutathione (GSH), oxidized glutathione (GSSG), glutathione reductase (GR), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT), thiobarbituric acid reactive substances (TBARS), as well as U concentrations. The results show that U significantly accumulated in hippocampus, cerebellum and cortex after 3 months of exposure. Moreover, UAD exposure promoted oxidative stress in these cerebral tissues. In cortex and cerebellum, TBARS levels were positively correlated with the U content, while in cerebellum GSSG and GSH levels were positively and negatively correlated, respectively, with U concentrations. In hippocampus, CAT and SOD activities were positively correlated with U concentration. The present results suggest that chronic oral exposure to UAD can cause progressive perturbations on physiological brain levels of oxidative stress markers. Although at the current UAD doses restraint scarcely showed additional adverse effects, its potential influence should not be underrated

  18. Intrinsic stress of bismuth oxide thin films: effect of vapour chopping and air ageing

    International Nuclear Information System (INIS)

    Patil, R B; Puri, R K; Puri, V

    2008-01-01

    Bismuth oxide thin films of thickness 1000 A 0 have been prepared by thermal oxidation (in air) of vacuum evaporated bismuth thin films (on glass substrate) at different oxidation temperatures and duration. Both the vapour chopped and nonchopped bismuth oxide thin films showed polycrystalline and polymorphic structure. The monoclinic bismuth oxide was found to be predominant in both the cases. The effect of vapour chopping and air exposure for 40 days on the intrinsic stress of bismuth oxide thin films has been studied. The vapour chopped films showed low (3.92 - 4.80 x 10 9 N/m 2 ) intrinsic stress than those of nonchopped bismuth oxide thin films (5.77 - 6.74 x 10 9 N/m 2 ). Intrinsic stress was found to increase due to air ageing. The effect of air ageing on the vapour chopped films was found low. The vapour chopped films showed higher packing density. Higher the packing density, lower the film will age. The process of chopping vapour flow creates films with less inhomogenety i.e. a low concentration of flaws and non-planar defects which results in lower intrinsic stress

  19. Protective effects of carnosol against oxidative stress induced brain damage by chronic stress in rats.

    Science.gov (United States)

    Samarghandian, Saeed; Azimi-Nezhad, Mohsen; Borji, Abasalt; Samini, Mohammad; Farkhondeh, Tahereh

    2017-05-04

    Oxidative stress through chronic stress destroys the brain function. There are many documents have shown that carnosol may have a therapeutic effect versus free radical induced diseases. The current research focused the protective effect of carnosol against the brain injury induced by the restraint stress. The restraint stress induced by keeping animals in restrainers for 21 consecutive days. Thereafter, the rats were injected carnosol or vehicle for 21 consecutive days. At the end of experiment, all the rats were subjected to his open field test and forced swimming test. Afterwards, the rats were sacrificed for measuring their oxidative stress parameters. To measure the modifications in the biochemical aspects after the experiment, the activities of malondialdehyde (MDA), reduced glutathione (GSH), as well as superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and catalase (CAT) were evaluated in the whole brain. Our data showed that the animals received chronic stress had a raised immobility time versus the non-stressed animals (p < 0.01). Furthermore, chronic stress diminished the number of crossing in the animals that were subjected to the chronic stress versus the non-stressed rats (p < 0.01). Carnosol ameliorated this alteration versus the non-treated rats (p < 0.05). In the vehicle treated rats that submitted to the stress, the level of MDA levels was significantly increased (P < 0.001), and the levels of GSH and antioxidant enzymes were significantly decreased versus the non-stressed animals (P < 0.001). Carnosol treatment reduced the modifications in the stressed animals as compared with the control groups (P < 0.001). All of these carnosol effects were nearly similar to those observed with fluoxetine. The current research shows that the protective effects of carnosol may be accompanied with enhanced antioxidant defenses and decreased oxidative injury.

  20. Stress vulnerability and the effects of moderate daily stress on sleep polysomnography and subjective sleepiness.

    Science.gov (United States)

    Petersen, Helena; Kecklund, Göran; D'Onofrio, Paolo; Nilsson, Jens; Åkerstedt, Torbjörn

    2013-02-01

    The purpose of this study was to investigate if and how sleep physiology is affected by naturally occurring high work stress and identify individual differences in the response of sleep to stress. Probable upcoming stress levels were estimated through weekly web questionnaire ratings. Based on the modified FIRST-scale (Ford insomnia response to stress) participants were grouped into high (n = 9) or low (n = 19) sensitivity to stress related sleep disturbances (Drake et al., 2004). Sleep was recorded in 28 teachers with polysomnography, sleep diaries and actigraphs during one high stress and one low stress condition in the participants home. EEG showed a decrease in sleep efficiency during the high stress condition. Significant interactions between group and condition were seen for REM sleep, arousals and stage transitions. The sensitive group had an increase in arousals and stage transitions during the high stress condition and a decrease in REM, whereas the opposite was seen in the resilient group. Diary ratings during the high stress condition showed higher bedtime stress and lower ratings on the awakening index (insufficient sleep and difficulties awakening). Ratings also showed lower cognitive function and preoccupation with work thoughts in the evening. KSS ratings of sleepiness increased during stress for the sensitive group. Saliva samples of cortisol showed no effect of stress. It was concluded that moderate daily stress is associated with a moderate negative effect on sleep sleep efficiency and fragmentation. A slightly stronger effect was seen in the sensitive group. © 2012 European Sleep Research Society.

  1. Atorvastatin reduces malondialdehyde concentrations in patients with polycystic ovary syndrome.

    Science.gov (United States)

    Sathyapalan, Thozhukat; Shepherd, John; Coady, Anne-Marie; Kilpatrick, Eric S; Atkin, Stephen L

    2012-11-01

    It has been shown that there is an increase in oxidative stress in polycystic ovary syndrome (PCOS). Statins are considered to have a pleiotropic effect other than their lipid-lowering effect. These effects may be mediated in part by reducing oxidative stress. This randomized, double-blind, placebo-controlled study was conducted to assess the effect of atorvastatin on serum malondialdehyde (MDA) concentrations as a marker of oxidative stress in patients with PCOS. Forty medication-naïve patients with PCOS were randomized to either atorvastatin 20 mg daily or placebo for 3 months. A 3-month extension study for both groups of patients was undertaken with metformin 1500 mg daily after completing initial 3 months of atorvastatin or placebo. There was a significant decrease of MDA concentrations with atorvastatin [mean (sem)] [0.29 (0.04) vs. 0.25 (0.02) μmol/liter; P polycystic ovary syndrome that was independently predicted by changes in testosterone, 25OHD, and high-sensitivity C-reactive protein.

  2. Effect of stress management interventions on job stress among nurses working in critical care units.

    Science.gov (United States)

    Light Irin, C; Bincy, R

    2012-01-01

    Stress in nurses affects their health and increases absenteeism, attrition rate, injury claims, infection rates and errors in treating patients. This in turn significantly increases the cost of employment in healthcare units. Proper management of stress ensures greater efficiency at work place and improved wellbeing of the employee. Therefore, a pre-experimental study was conducted among 30 Critical Care Unit nurses working inMedical College Hospital, Thiruvananthapuram, (Kerala) to assess the effect of stress management interventions such as Job Stress Awareness, Assertiveness Training, Time Management, andProgressive Muscle Relaxation on job stress. The results showed that caring for patients, general job requirements and workload were the major sources of stress for the nurses. The level of severe stress was reduced from 60 percent to 20 percent during post-test. The Stress Management Interventions were statistically effective in reducing the stress of nurses at p<0.001 level.

  3. No effects of psychosocial stress on intertemporal choice.

    Directory of Open Access Journals (Sweden)

    Johannes Haushofer

    Full Text Available Intertemporal choices - involving decisions which trade off instant and delayed outcomes - are often made under stress. It remains unknown, however, whether and how stress affects intertemporal choice. We subjected 142 healthy male subjects to a laboratory stress or control protocol, and asked them to make a series of intertemporal choices either directly after stress, or 20 minutes later (resulting in four experimental groups. Based on theory and evidence from behavioral economics and cellular neuroscience, we predicted a bidirectional effect of stress on intertemporal choice, with increases in impatience or present bias immediately after stress, but decreases in present bias or impatience when subjects are tested 20 minutes later. However, our results show no effects of stress on intertemporal choice at either time point, and individual differences in stress reactivity (changes in stress hormone levels over time are not related to individual differences in intertemporal choice. Together, we did not find support for the hypothesis that psychosocial laboratory stressors affect intertemporal choice.

  4. Effect of heavy metal stress on the catalase activity and expression of isozymes in the leaves of rice seedling

    International Nuclear Information System (INIS)

    Ge Cailin; Yang Xiaoyong; Zhu Hongxia; Wang Zegang; Luo Shishi; Ma Fei; Sun Jinhe

    2002-01-01

    The effect of heavy metal stress on the catalase (CAT) activity and expression of isozymes in the leaves of rice (Wuyujing, Yangdao 6, Shanyou 818) seedling was measured and analyzed. The results showed as follows. (1) When the concentration of Cu, Cd and Hg was in the range of 0.05-2.0 mM, the CAT activity decreased continuously with the concentration of Cu and Cd increasing. However, with the concentration of Hg increasing the CAT activity rapidly decreased first, and then increased slightly, and again decreased obviously, indicating that the Cu, Cd and Hg of 0.05-2.0 mM inhibited the CAT activity in the leaves of rice seedling. (2) The results by using polyacrylamide concentration gradient gel electrophoresis technique to analyze the CAT isozymes indicated that, on the normal condition, there were 1 to 2 CAT isozymes being expressed in the rice leaves (2 CAT isozymes being expressed in Wuyujing leaves, 1 CAT isozymes in Yangdao 6 and Shanyou 818 leaves). 0.1 mM Cd stress induced Wuyujing leaves to express 1 new CAT isozymes, 0.1 mM Cd and Hg stress also induced Yangdao 6 leaves to express 1 new CAT isozymes, but the expression of CAT isozymes, which were expressed in normal condition, were inhibited by Cu, Cd and Hg stress

  5. Method for automatic determination of soybean actual evapotranspiration under open top chambers (OTC) subjected to effects of water stress and air ozone concentration.

    Science.gov (United States)

    Rana, Gianfranco; Katerji, Nader; Mastrorilli, Marcello

    2012-10-01

    The present study describes an operational method, based on the Katerji et al. (Eur J Agron 33:218-230, 2010) model, for determining the daily evapotranspiration (ET) for soybean inside open top chambers (OTCs). It includes two functions, calculated day par day, making it possible to separately take into account the effects of concentrations of air ozone and plant water stress. This last function was calibrated in function of the daily values of actual water reserve in the soil. The input variables of the method are (a) the diurnal values of global radiation and temperature, usually measured routinely in a standard weather station; (b) the daily values of the AOT40 index accumulated (accumulated ozone over a threshold of 40 ppb during daylight hours, when global radiation exceeds 50 Wm(-2)) determined inside the OTC; and (c) the actual water reserve in the soil, at the beginning of the trial. The ensemble of these input variables can be automatable; thus, the proposed method could be applied in routine. The ability of the method to take into account contrasting conditions of ozone air concentration and water stress was evaluated over three successive years, for 513 days, in ten crop growth cycles, excluding the days employed to calibrate the method. Tests were carried out in several chambers for each year and take into account the intra- and inter-year variability of ET measured inside the OTCs. On the daily scale, the slope of the linear regression between the ET measured by the soil water balance and that calculated by the proposed method, under different water conditions, are 0.98 and 1.05 for the filtered and unfiltered (or enriched) OTCs with root mean square error (RMSE) equal to 0.77 and 1.07 mm, respectively. On the seasonal scale, the mean difference between measured and calculated ET is equal to +5% and +11% for the filtered and unfiltered OTCs, respectively. The ability of the proposed method to estimate the daily and seasonal ET inside the OTCs is

  6. The Dichotomous Effect of Chronic Stress on Obesity.

    Science.gov (United States)

    Razzoli, Maria; Bartolomucci, Alessandro

    2016-07-01

    Obesity and metabolic diseases are linked to chronic stress and low socioeconomic status. The mechanistic link between stress and obesity has not been clarified, partly due to the inherent complexity exemplified by the bidirectional effect of stress on eating and body weight. Recent studies focusing on adaptive thermogenesis and brown adipose tissue (BAT) function support a dichotomous relation to explain the impact of stress on obesity: stress promotes obesity in the presence of hyperphagia and unchanged BAT function; stress results in weight loss and/or obesity resistance in the presence of hypophagia, or when hyperphagia is associated with BAT recruitment and enhanced thermogenesis. Mechanistically dissecting the bidirectional effects of stress on metabolic outcomes might open new avenues for innovative pharmacotherapies for the treatment of obesity-associated diseases. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Extraversion and cardiovascular responses to recurrent social stress: Effect of stress intensity.

    Science.gov (United States)

    Lü, Wei; Xing, Wanying; Hughes, Brian M; Wang, Zhenhong

    2017-10-28

    The present study sought to establish whether the effects of extraversion on cardiovascular responses to recurrent social stress are contingent on stress intensity. A 2×5×1 mixed-factorial experiment was conducted, with social stress intensity as a between-subject variable, study phase as a within-subject variable, extraversion as a continuous independent variable, and cardiovascular parameter (HR, SBP, DBP, or RSA) as a dependent variable. Extraversion (NEO-FFI), subjective stress, and physiological stress were measured in 166 undergraduate students randomly assigned to undergo moderate (n=82) or high-intensity (n=84) social stress (a public speaking task with different levels of social evaluation). All participants underwent continuous physiological monitoring while facing two consecutive stress exposures distributed across five laboratory phases: baseline, stress exposure 1, post-stress 1, stress exposure 2, post-stress 2. Results indicated that under moderate-intensity social stress, participants higher on extraversion exhibited lesser HR reactivity to stress than participants lower on extraversion, while under high-intensity social stress, they exhibited greater HR, SBP, DBP and RSA reactivity. Under both moderate- and high-intensity social stress, participants higher on extraversion exhibited pronounced SBP and DBP response adaptation to repeated stress, and showed either better degree of HR recovery or greater amount of SBP and DBP recovery after stress. These findings suggest that individuals higher on extraversion exhibit physiological flexibility to cope with social challenges and benefit from adaptive cardiovascular responses. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Dependence of Shear and Concentration on Fouling in a Membrane Bioreactor with Rotating Membrane Discs

    DEFF Research Database (Denmark)

    Jørgensen, Mads Koustrup; Pedersen, Malene Thostrup; Christensen, Morten Lykkegaard

    2014-01-01

    Rotating ceramic membrane discs were fouled with lab-scale membrane bioreactors (MBR) sludge. Sludge filtrations were performed at varying rotation speeds and in different concentric rings of the membranes on different sludge concentrations. Data showed that the back transport expressed by limiting...... flux increased with rotation speed and distance from membrane center as an effect of shear. Further, the limiting flux decreased with increasing sludge concentration. A model was developed to link the sludge concentration and shear stress to the limiting flux. The model was able to simulate the effect...... of shear stress and sludge concentration on the limiting flux. The model was developed by calculating the shear rate at laminar flow regime at different rotation speeds and radii on the membrane. Furthermore, through the shear rate and shear stress, the non-Newtonian behavior of MBR sludge was addressed...

  9. Effect of Layer-Graded Bond Coats on Edge Stress Concentration and Oxidation Behavior of Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dongming; Ghosn, Louis J.; Miller, Robert A.

    1998-01-01

    Thermal barrier coating (TBC) durability is closely related to design, processing and microstructure of the coating Z, tn systems. Two important issues that must be considered during the design of a thermal barrier coating are thermal expansion and modulus mismatch between the substrate and the ceramic layer, and substrate oxidation. In many cases, both of these issues may be best addressed through the selection of an appropriate bond coat system. In this study, a low thermal expansion and layer-graded bond coat system, that consists of plasma-sprayed FeCoNiCrAl and FeCrAlY coatings, and a high velocity oxyfuel (HVOF) sprayed FeCrAlY coating, is developed to minimize the thermal stresses and provide oxidation resistance. The thermal expansion and oxidation behavior of the coating system are also characterized, and the strain isolation effect of the bond coat system is analyzed using the finite element method (FEM). Experiments and finite element results show that the layer-graded bond coat system possesses lower interfacial stresses. better strain isolation and excellent oxidation resistance. thus significantly improving the coating performance and durability.

  10. The Effects of Foliar Application of Methanol on Morphological Characteristics of Bean (Phaseolus vulgaris L. under Drought Stress Condition

    Directory of Open Access Journals (Sweden)

    N. Armand

    2016-02-01

    Full Text Available Introduction Available water is an important factor for plant growth in arid environments. Results indicated that foliar application of methanol is believed to be more important than the drought tolerance in C3 plant. Since bean is a C3 plant, it performs light respiration under intense heat, light and water stress due to internal leaf CO2 concentration reduction and oxygen concentration increase. Light respiration can cause up to 20% loss of carbon in plants and decrease the yield. Increasing concentration of carbon dioxide can neutralize the effect caused by drought stress. Thus, the use of substances that can cause an increase in the concentration of carbon dioxide in the plant, leads to improving the yield under the drought conditions. One of the ways of increasing the concentration of carbon dioxide in plants is by using compounds such as methanol, ethanol, propanol, butanol as well as use of the amino acids of glycine, glutamate and aspartate. Plants can easily absorb methanol sprayed on leaves and use it as a carbon source added to atmospheric carbon. Methanol is relatively smaller compared to the CO2 molecules, so it can be easily absorbed and utilized by plants. Materials and Methods In order to evaluate the effects of foliar application of methanol on some morphological characteristics of bean under drought stress, a factorial experiment was conducted based on completely randomized block design with three replications in 2014 at the Khatam Alanbia University of Behbahan. The treatment of spraying methanol was at 4 levels include control (without spraying, 10, 20 and 30% v/v methanol which added 2 g l-1 glycine to each of solutions. Adding glycine to aqueous solution of methanol leads to prevention of damages caused by the toxicity of methanol. The drought factors including control (100% field of capacity, moderate drought stress (50% field of capacity and severe drought stress (25% field of capacity were considered. In this experiment

  11. The distorting effect of varying diets on fecal glucocorticoid measurements as indicators of stress

    DEFF Research Database (Denmark)

    Kalliokoski, Otto; Teilmann, A. Charlotte; Abelson, Klas S. P.

    2015-01-01

    The physiological stress response is frequently gauged in animals, non-invasively, through measuring glucocorticoids in excreta. A concern with this method is, however, the unknown effect of variations in diets on the measurements. With an energy dense diet, leading to reduced defecation, will low...... concentrations of glucocorticoids be artificially inflated? Can this effect be overcome by measuring the total output of glucocorticoids in excreta? In a controlled laboratory setting we explored the effect in mice. When standard mouse chow – high in dietary fiber – was replaced with a 17% more energy-dense diet...

  12. Effect of clear bands on intergranular stresses and IASCC early damage - 04002

    International Nuclear Information System (INIS)

    Sauzay, M.; Ould Moussa, M.; Diawara, B.; Lebreau, F.

    2016-01-01

    Slip localization is a common feature in post-irradiated metallic poly-crystals undergoing tensile straining. This effect takes place for instance in the form of thin slip bands called channels or clear bands, formed after the local vanishing of irradiation defects induced interactions with gliding dislocations. Channel impingement towards grain boundaries (GBs) should induce local stress concentrations along GBs, in the quasi-elastic surrounding matrix. It has been shown extensively that this trigger GB crack initiation. Grain boundary fracture is simulated using a double criterion based on both critical normal stress and fracture energy as deduced from atomistic computations of GB fracture. The critical stress is deduced from the fracture energy using the universal-binding-energy relationship (UBER). In the case of brittle fracture, the fracture energy is defined as the two fresh free surface energy values minus the GB energy. In relationship with the more complex topic of irradiation induced stress corrosion cracking (IASCC) occurring in-service conditions, the influence of irradiation dose, strain rate and irradiation creep is discussed. Due to the complex loading history highlighted by structural finite element analysis, strain peaks may induce the formation of clear bands or twin bands. The study of the effect of irradiation creep on the relaxation of the induced GB stress fields shows clearly that the relaxation requires many months due to the linear irradiation creep law. Such durations allows GB oxidation mechanisms to occur leading to a weakening of the GB fracture parameters in the vicinity of the free surfaces. This short paper is followed by the slides of the presentation

  13. Relationship between general intelligence, emotional intelligence, stress levels and stress reactivity.

    Science.gov (United States)

    Singh, Yogesh; Sharma, Ratna

    2012-07-01

    Stressful life events and daily life stresses have both deleterious and cumulative effects on human body. In several studies, stress has been shown to affect various parameter of higher mental function like attention, concentration, learning and memory. Present study was designed to explore the relationship among GI level, EI level, psychological stress levels and acute stress reactivity in young normal healthy subjects. The study was conducted on thirty four healthy male student volunteers to study a) acute stress reactivity in subjects with varying levels of General Intelligence (GI) and Emotional Intelligence (EI) and b) correlation between GI, EI, acute stress and perceived stress. Baseline GI and EI and acute stress and perceived stress scores were measured by standard assessment scales. Using median value of GI and EI scores as cutoff values, subjects were categorized into four groups. Among different GI-EI groups, acute stress reactivity was similar but salivary Cortisol (especially post stressor level) and perceived stress level was a differentiating factor. High level of EI was associated inversely with acute and chronic perceived stress level. Significant correlation was found between acute and chronic perceived stress levels. Level of general intelligence showed no relation to acute or chronic stress levels as well as acute stress reactivity. The differences in various groups of GI and EI had no effect on the baseline and post stress performance on Sternberg memory test and all the three conditions of Stroop test. In conclusion emotional intelligence as an attribute is better suited to handle day to day acute stress and chronic perceived stress.

  14. Effect of aspartame on biochemical and oxidative stress parameters in rat blood

    Directory of Open Access Journals (Sweden)

    Prokić Marko D.

    2015-01-01

    Full Text Available Aspartame (ASP is one of the most widely used nonnutritive sweeteners. This study investigates the chronic effects of ASP on hematological and biochemical parameters, and its effects on the oxidative/antioxidative status in the red blood cells of Wistar albino rats. Rats were provided with ASP (40 mg/kg/daily for six weeks in drinking water. Increased food and fluid intake was observed in the ASP-treated rats. Total body mass was significantly decreased in the ASP-treated rats. Treatment with ASP caused an increase in the concentrations of glucose, cholesterol, LDL-cholesterol, and in the activities of alanine aminotransferase (ALT, aspartate aminotransferase (AST and lactate dehydrogenase (LDH, as well as a decrease in the levels of HDL-cholesterol in the serum. A significant decline in the number of white blood cells (WBC was observed after ASP uptake. Based on the results we conclude that ASP induces oxidative stress, observed as an alteration of the glutathione redox status, which leads to increased concentrations of nitric oxide (NO and lipid peroxides (LPO in the red blood cells. Changes in biochemical parameters, lipid metabolism, as well as changes in the levels of oxidative stress markers and the appearance of signs of liver damage indicate that chronic use of ASP can lead to the development of hyperglycemia, hypercholesterolemia and associated diseases. [Projekat Ministarstva nauke Republike Srbije, br. 173041

  15. Overcoming the effects of stress on reactor operator performance

    International Nuclear Information System (INIS)

    He Xuhong; Wei Li; Zhao Bingquan

    2003-01-01

    Reactor operators may be exposed to significant levels of stress during plant emergencies and their performance may be affected by the stress. This paper first identified the potential sources of stress in the nuclear power plant, then discussed the ways in which stress is likely to affect the reactor operators, and finally identified several training approaches for reducing or eliminating stress effects. The challenges for effective stress reducing training may seem daunting, yet the challenges are real and must be addressed. This paper reviewed researches in training design, knowledge and skill acquisition, and training transfer point to a number of strategies that can be used to address these challenges and lead to more effective training and development. (author)

  16. Overcoming the effects of stress on reactor operator performance

    Energy Technology Data Exchange (ETDEWEB)

    He Xuhong; Wei Li; Zhao Bingquan [Tsinghua Univ., Nuclear Power Plant Simulation Training Center, Beijing (China)

    2003-03-01

    Reactor operators may be exposed to significant levels of stress during plant emergencies and their performance may be affected by the stress. This paper first identified the potential sources of stress in the nuclear power plant, then discussed the ways in which stress is likely to affect the reactor operators, and finally identified several training approaches for reducing or eliminating stress effects. The challenges for effective stress reducing training may seem daunting, yet the challenges are real and must be addressed. This paper reviewed researches in training design, knowledge and skill acquisition, and training transfer point to a number of strategies that can be used to address these challenges and lead to more effective training and development. (author)

  17. Neuroprotective effect of a new variant of Epo nonhematopoietic against oxidative stress

    Directory of Open Access Journals (Sweden)

    C. Castillo

    2018-04-01

    Full Text Available Human erythropoietin is mainly recognized for its hematopoietic function; however, by binding to its receptor (EpoR, it can activate different signaling pathways as STAT, PI3K, MAPK and RAS to increase cellular differentiation or provide neuroprotective effects, among others. A recombinant human erythropoietin variant with low glycosylation and without hematopoietic effect (EpoL was purified from skimmed goat milk. Recombinant human erythropoietin (Epo was obtained from CHO cell line and used as control to compare EpoL effects. Neuroprotection studies were performed in PC12 cells and rat hippocampal slices. Cells were pretreated during 1 h with EpoL or Epo and exposed to oxidative agents (H2O2 or FCCP; cell viability was assayed at the end of the experiment by the MTT method. Hippocampal slices were exposed to 15 min of oxygen and glucose deprivation (OGD and the neuroprotective drugs EpoL or Epo were incubated for 2 h post-OGD in re-oxygenated medium. Cell cultures stressed with oxidative agents, and pretreated with EpoL, showed neuroprotective effects of 30% at a concentration 10 times lower than that of Epo. Moreover, similar differences were observed in OGD ex vivo assays. Neuroprotection elicited by EpoL was lost when an antibody against EpoR was present, indicating that its effect is EpoR-dependent. In conclusion, our results suggest that EpoL has a more potent neuroprotective profile than Epo against oxidative stress, mediated by activation of EpoR, thus EpoL represents an important target to develop a potential biopharmaceutical to treat different central nervous system pathologies related to oxidative stress such as stroke or neurodegenerative diseases. Keywords: Erythropoietin, Erythropoietin receptor, Neuroprotection, Oxidative stress

  18. Stress hormone epinephrine (adrenaline) and norepinephrine (noradrenaline) effects on the anaerobic bacteria.

    Science.gov (United States)

    Boyanova, Lyudmila

    2017-04-01

    Microbial endocrinology is a relatively new research area that already encompasses the anaerobes. Stress hormones, epinephrine and norepinephrine, can affect the growth of anaerobic bacteria such as Fusobacterium nucleatum, Prevotella spp., Porhyromonas spp., Tanerella forsythia and Propionibacterium acnes and can increase virulence gene expression, iron acquisition and many virulence factors of some anaerobic species such as Clostridium perfringens, Porphyromonas gingivalis and Brachyspira pilosicoli. Epinephrine and norepinephrine effects can lead to a growth increase or decrease, or no effect on the growth of the anaerobes. The effects are species-specific and perhaps strain-specific. Discrepancies in the results of some studies can be due to the different methods and media used, catecholamine concentrations, measurement techniques and the low number of strains tested. Biological effects of the stress hormones on the anaerobes may range from halitosis and a worsening of periodontal diseases to tissue damages and atherosclerotic plaque ruptures. Optimizations of the research methods and a detailed assessment of the catecholamine effects in conditions mimicking those in affected organs and tissues, as well as the effects on the quorum sensing and virulence of the anaerobes and the full spectrum of biological consequences of the effects are interesting topics for further evaluation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Study of stress, self-esteem and depression in medical students and effect of music on perceived stress.

    Science.gov (United States)

    Baste, Vrushali S; Gadkari, Jayashree V

    2014-01-01

    Medical students are exposed to many stressors and if stress is perceived negatively or becomes excessive can affect academic performance and health adversely. The objective of this study was to assess stress, predominant stressor and effect of music on perceived stress. 90 undergraduate students were selected randomly. A written questionnaire about personal information, stressful factors, ways to cope up stress, Rosenberg self-esteem scale (Rosenberg, 1965) and 'Quick Inventory of Depressive Symptomatology' self-rated 16 (QIDS-SR-16) was given.45.6% Students had mild stress, 7.7% students had moderate stress and 1.1% students had severe stress. Academic factors were the predominant cause of stress in most students, followed by physical, social and emotional. On Rosenberg self-esteem scale (Rosenberg, 1965) 85.6% students had high self-esteem and on QIDS-SR16 50% students had depression. Effect of music on perceived stress was statistically significant. Medical curriculum is associated with increased stress in students. Music can be used as simple, inexpensive and effective therapy for stress.

  20. Immediate recall influences the effects of pre-encoding stress on emotional episodic long-term memory consolidation in healthy young men.

    Science.gov (United States)

    Wolf, Oliver T

    2012-05-01

    The stress-associated activation of the hypothalamus-pituitary-adrenal axis influences memory. Several studies have supported the notion that post-learning stress enhances memory consolidation, while pre-retrieval stress impairs retrieval. Findings regarding the effects of pre-encoding stress, in contrast, have been rather inconsistent. In the current two studies, the impact of an immediate retrieval task on these effects was explored. In the first study, 24 healthy young male participants were exposed to a psychosocial laboratory stressor (Trier Social Stress Test) or a control condition before viewing positive, negative, and neutral photographs, which were accompanied by a brief narrative. Immediate as well as delayed (24 h later) free recall was assessed. Stress was expected to enhance emotional long-term memory without affecting immediate recall performance. Stress caused a significant increase in salivary cortisol concentrations but had no significant effects on immediate or delayed retrieval performance, even though a trend toward poorer memory of the stress group was apparent. Based on these findings, the second experiment tested the hypothesis that the beneficial effects of stress on emotional long-term memory performance might be abolished by an immediate recall test. In the second study (n = 32), the same design was used, except for the omission of the immediate retrieval test. This time stressed participants recalled significantly more negative photographs compared to the control group. The present study indicates that an immediate retrieval attempt of material studied after stress exposure can prevent or even reverse the beneficial effects of pre-encoding stress on emotional long-term memory consolidation.

  1. Effects of stress on heart rate complexity--a comparison between short-term and chronic stress.

    Science.gov (United States)

    Schubert, C; Lambertz, M; Nelesen, R A; Bardwell, W; Choi, J-B; Dimsdale, J E

    2009-03-01

    This study examined chronic and short-term stress effects on heart rate variability (HRV), comparing time, frequency and phase domain (complexity) measures in 50 healthy adults. The hassles frequency subscale of the combined hassles and uplifts scale (CHUS) was used to measure chronic stress. Short-term stressor reactivity was assessed with a speech task. HRV measures were determined via surface electrocardiogram (ECG). Because respiration rate decreased during the speech task (pshort-term stress decreased HR D2 (calculated via the pointwise correlation dimension PD2) (pshort-term stress. Partial correlation adjusting for respiration rate showed that HR D2 was associated with chronic stress (r=-.35, p=.019). Differential effects of chronic and short-term stress were observed on several HRV measures. HR D2 decreased under both stress conditions reflecting lowered functionality of the cardiac pacemaker. The results confirm the importance of complexity metrics in modern stress research on HRV.

  2. When does stress help or harm? The effects of stress controllability and subjective stress response on Stroop performance.

    OpenAIRE

    Roselinde Kaiser Henderson; Hannah R. Snyder; Tina eGupta; Marie T. Banich; Marie T. Banich

    2012-01-01

    The ability to engage in goal-directed behavior despite exposure to stress is critical to resilience. Questions of how stress can impair or improve behavioral functioning are important in diverse settings, from athletic competitions to academic testing to clinical therapy. Previous research suggests that controllability is a key factor in the impact of stress on behavior: learning how to control stressors buffers people from the negative effects of stress on subsequent cognitively demanding ...

  3. When Does Stress Help or Harm? The Effects of Stress Controllability and Subjective Stress Response on Stroop Performance

    OpenAIRE

    Henderson, Roselinde K.; Snyder, Hannah R.; Gupta, Tina; Banich, Marie T.

    2012-01-01

    The ability to engage in goal-directed behavior despite exposure to stress is critical to resilience. Questions of how stress can impair or improve behavioral functioning are important in diverse settings, from athletic competitions to academic testing. Previous research suggests that controllability is a key factor in the impact of stress on behavior: learning how to control stressors buffers people from the negative effects of stress on subsequent cognitively demanding tasks. In addition, r...

  4. Acute stress does not affect the impairing effect of chronic stress on memory retrieval

    Science.gov (United States)

    Ozbaki, Jamile; Goudarzi, Iran; Salmani, Mahmoud Elahdadi; Rashidy-Pour, Ali

    2016-01-01

    Objective(s): Due to the prevalence and pervasiveness of stress in modern life and exposure to both chronic and acute stresses, it is not clear whether prior exposure to chronic stress can influence the impairing effects of acute stress on memory retrieval. This issue was tested in this study. Materials and Methods: Adult male Wistar rats were randomly assigned to the following groups: control, acute, chronic, and chronic + acute stress groups. The rats were trained with six trials per day for 6 consecutive days in the water maze. Following training, the rats were either kept in control conditions or exposed to chronic stress in a restrainer 6 hr/day for 21 days. On day 22, a probe test was done to measure memory retention. Time spent in target and opposite areas, platform location latency, and proximity were used as indices of memory retention. To induce acute stress, 30 min before the probe test, animals received a mild footshock. Results: Stressed animals spent significantly less time in the target quadrant and more time in the opposite quadrant than control animals. Moreover, the stressed animals showed significantly increased platform location latency and proximity as compared with control animals. No significant differences were found in these measures among stress exposure groups. Finally, both chronic and acute stress significantly increased corticosterone levels. Conclusion: Our results indicate that both chronic and acute stress impair memory retrieval similarly. Additionally, the impairing effects of chronic stress on memory retrieval were not influenced by acute stress. PMID:27635201

  5. [Effects of exogenous spermidine on Cucumis sativus L. seedlings photosynthesis under root zone hypoxia stress].

    Science.gov (United States)

    Wang, Tian; Wang, Suping; Guo, Shirong; Sun, Yanjun

    2006-09-01

    With water culture, this paper studied the effects of exogenous spermidine (Spd) on the net photosynthetic rate (Pn), intercellular CO2 concentrations (Ci), stomatal conductance (Gs), transpiration rate (Tr), apparent quantum yield (phi c), and carboxylation efficiency (CE) of cucumber seedlings tinder hypoxia stress. The results showed that the Pn decreased gradually under hypoxia stress, and reached the minimum 10 days after by 63. 33% of the control. Compared with that of hypoxia-stressed plants, the Pn after 10 days application of exogenous Spd increased 1.25 times. A negative correlation (R2 = 0.4730 - 0.7118) was found between Pn and Ci. Gs and Tr changed in wider ranges, which decreased under hypoxia-stress, but increased under hypoxia-stress plus exogenous Spd application. There was a significant positive correlation between Gs and Tr (R2 = 0.7821 - 0.9458), but these two parameters had no significant correlation with Pn; Hypoxia stress induced a decrease of phi c and CE by 63.01% and 72.33%, respectively, while hypoxia stress plus exogenous Spd application made phi c and CE increase by 23% and 14%, respectively. The photo-inhibition of cucumber seedlings under hypoxia stress was mainly caused by non-stomatal limitation, while exogenous Spd alleviated the hypoxia stress by repairing photosynthesis system.

  6. Isoprene in poplar emissions: effects on new particle formation and OH concentrations

    Directory of Open Access Journals (Sweden)

    A. Kiendler-Scharr

    2012-01-01

    Full Text Available Stress-induced volatile organic compound (VOC emissions from transgenic Grey poplar modified in isoprene emission potential were used for the investigation of photochemical secondary organic aerosol (SOA formation. In poplar, acute ozone stress induces the emission of a wide array of VOCs dominated by sesquiterpenes and aromatic VOCs. Constitutive light-dependent emission of isoprene ranged between 66 nmol m−2 s−1 in non-transgenic controls (wild type WT and nearly zero (<0.5 nmol m−2 s−1 in isoprene emission-repressed plants (line RA22, respectively. Nucleation rates of up to 3600 cm−3 s−1 were observed in our experiments. In the presence of isoprene new particle formation was suppressed compared to non-isoprene containing VOC mixtures. Compared to isoprene/monoterpene systems emitted from other plants the suppression of nucleation by isoprene was less effective for the VOC mixture emitted from stressed poplar. This is explained by the observed high efficiency of new particle formation for emissions from stressed poplar. Direct measurements of OH in the reaction chamber revealed that the steady state concentration of OH is lower in the presence of isoprene than in the absence of isoprene, supporting the hypothesis that isoprenes' suppressing effect on nucleation is related to radical chemistry. In order to test whether isoprene contributes to SOA mass formation, fully deuterated isoprene (C5D8 was added to the stress-induced emission profile of an isoprene free poplar mutant. Mass spectral analysis showed that, despite the isoprene-induced suppression of particle formation, fractions of deuterated isoprene were incorporated into the SOA. A fractional mass yield of 2.3% of isoprene was observed. Future emission changes due to land use and climate change may therefore affect both gas phase oxidation capacity and new particle number formation.

  7. Sex differences in stress effects on emotional learning.

    Science.gov (United States)

    Merz, Christian J; Wolf, Oliver T

    2017-01-02

    Stress influences emotional learning and memory processes. These effects are thought to underlie stress-associated mental disorders. Sex differences in stress reactivity and in central nervous system stress sensitivity illustrate the important modulatory role of sex hormones. This Review outlines how stress hormones influence different stages of the fear conditioning process, such as fear acquisition, extinction, and retrieval. Results will be compared with findings on the impact of stress on episodic memory. The focus is on the available human data on sex differences and the impact sex hormones have on the stress effects on emotional learning and memory. It will become apparent that the menstrual cycle but also the intake of hormonal contraceptives modulates the impact of stress on brain and behavior. Additional basic research is needed for a deeper insight regarding the interplay between stress and sex hormones in emotion and cognition. In addition, new treatment options might be derived to optimize existing strategies such as exposure therapy, which relies on the principles of fear conditioning. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  8. Stress Symptoms: Effects on Your Body and Behavior

    Science.gov (United States)

    ... heart disease, obesity and diabetes. Common effects of stress on your body Headache Muscle tension or pain ... drive Stomach upset Sleep problems Common effects of stress on your mood Anxiety Restlessness Lack of motivation ...

  9. Effect of NaCl-Stress on Metabolism of NO3-, NH4+ and NO2- at Several Rice Varieties

    Directory of Open Access Journals (Sweden)

    M Zulman Harja Utama

    2010-09-01

    Full Text Available This study was conducted to evaluate the effect of NaCl-stress on metabolism of NO3-, NH4+ and NO2- at several rice varieties. The results showed that an addition of NaCl had lesser effect on NaCl-tolerant varieties as compared to NaCl-sensitive in term of reduction in NO3-, NH4+, and NO2- uptake. Rice adaptation ability to NaCl stress occurred through the mechanism of NO3-, NH4+, and N02- metabolism physiology. It was indicated by the difference concentration of NO3-, NH4+ and N02- between the tolerant (Cisadane, moderate (Batang Lembang, Rendah Kuning, and Batang Piaman and sensitive (IR 66 varieties. Concentration of NH4+ and N02- of tolerant rice (Cisadane at NaCl treatment were about 1.16 and 2.6 times higher than that at control, respectively, while concentration of NO3- was only 0.03 times lower than control. In contrast, concentration of NO3-, NH4+, and N02- of sensitive rice (IR 66, were about 0.09, 0.27, and 0.41 times lower than that in control respecting at NaCl treatment, respectively.

  10. Beneficial effect of hot spring bathing on stress levels in Japanese macaques.

    Science.gov (United States)

    Takeshita, Rafaela S C; Bercovitch, Fred B; Kinoshita, Kodzue; Huffman, Michael A

    2018-05-01

    The ability of animals to survive dramatic climates depends on their physiology, morphology and behaviour, but is often influenced by the configuration of their habitat. Along with autonomic responses, thermoregulatory behaviours, including postural adjustments, social aggregation, and use of trees for shelter, help individuals maintain homeostasis across climate variations. Japanese macaques (Macaca fuscata) are the world's most northerly species of nonhuman primates and have adapted to extremely cold environments. Given that thermoregulatory stress can increase glucocorticoid concentrations in primates, we hypothesized that by using an available hot spring, Japanese macaques could gain protection against weather-induced cold stress during winter. We studied 12 adult female Japanese macaques living in Jigokudani Monkey Park, Japan, during the spring birth season (April to June) and winter mating season (October to December). We collected faecal samples for determination of faecal glucocorticoid (fGC) metabolite concentrations by enzyme immunoassay, as well as behavioural data to determine time spent in the hot springs, dominance rank, aggression rates, and affiliative behaviours. We used nonparametric statistics to examine seasonal changes in hot spring bathing, and the relationship between rank and air temperature on hot spring bathing. We used general linear mixed-effect models to examine factors impacting hormone concentrations. We found that Japanese macaques use hot spring bathing for thermoregulation during the winter. In the studied troop, the single hot spring is a restricted resource favoured by dominant females. High social rank had both costs and benefits: dominant females sustained high fGC levels, which were associated with high aggression rates in winter, but benefited by priority of access to the hot spring, which was associated with low fGC concentrations and therefore might help reduce energy expenditure and subsequent body heat loss. This unique

  11. Subinhibitory concentrations of antibiotics affect stress and virulence gene expression in Listeria monocytogenes and cause enhanced stress sensitivity but do not affect Caco‐2 cell invasion

    DEFF Research Database (Denmark)

    Knudsen, Gitte Maegaard; Holch, Anne; Gram, Lone

    2012-01-01

    with promoter fusions, 14 of 16 antibiotics induced or repressed expression of one or more stress and/or virulence genes. Despite ampicillin‐induced up‐regulation of PinlA‐lacZ expression, Caco‐2 cell invasion was not affected. Subinhibitory concentrations of ampicillin and tetracycline caused up‐ and down...

  12. Effect of Oval Posts on Stress Distribution in Endodontically Treated Teeth: A Three-Dimensional Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Mojtaba Mahmoodi

    2017-09-01

    Full Text Available Introduction: In post-core crown restorations, the use of prefabricated composite posts concentrate stress at the cervical region and the use of metal posts (prefabricated and customized posts concentrates stress at the interfaces. Fiber reinforced composite posts (FRCs with oval cross-section (oval posts were proposed for post-core crown restorations to reduce the stress levels at the cervical region. The aim of the present study was to investigate the impact of oval cross-section composite posts on stress distribution of premolar with oval-shaped canal by using three-dimensional (3D finite element analysis. Materials and Methods: An extracted premolar tooth was mounted, sectioned, and photographed to create a 3D model. The surrounding tissues of the tooth, periodontal ligament, as well as cortical and trabecular bones were modeled. Seven taper posts with two different cross-section geometries (circular and oval shapes were modeled, as well. Then, the effect of post geometry, post material (carbon fiber and fiberglass, and cement material were investigated by 3D finite element analysis and the stress distribution results were compared. Results: In all the models, the highest stress levels of the dentin were accumulated at the coronal third of the root, and the highest stress levels at the bonding layers were accumulated at the cervical margin. Narrow circular posts induced the highest stress levels, whereas the stress levels were reduced by using thick oval posts. Application of elastic cement reduces the stress at the bonding layers but increases stress at the dentin. Conclusion: Finite element analysis showed that prefabricated oval posts are superior to traditional circular ones. The use of cement with low elastic modulus reduces the risk of debonding but raises the risk of root fracture.

  13. Stretching the stress boundary: Linking air pollution health effects to a neurohormonal stress response.

    Science.gov (United States)

    Kodavanti, Urmila P

    2016-12-01

    Inhaled pollutants produce effects in virtually all organ systems in our body and have been linked to chronic diseases including hypertension, atherosclerosis, Alzheimer's and diabetes. A neurohormonal stress response (referred to here as a systemic response produced by activation of the sympathetic nervous system and hypothalamus-pituitary-adrenal (HPA)-axis) has been implicated in a variety of psychological and physical stresses, which involves immune and metabolic homeostatic mechanisms affecting all organs in the body. In this review, we provide new evidence for the involvement of this well-characterized neurohormonal stress response in mediating systemic and pulmonary effects of a prototypic air pollutant - ozone. A plethora of systemic metabolic and immune effects are induced in animals exposed to inhaled pollutants, which could result from increased circulating stress hormones. The release of adrenal-derived stress hormones in response to ozone exposure not only mediates systemic immune and metabolic responses, but by doing so, also modulates pulmonary injury and inflammation. With recurring pollutant exposures, these effects can contribute to multi-organ chronic conditions associated with air pollution. This review will cover, 1) the potential mechanisms by which air pollutants can initiate the relay of signals from respiratory tract to brain through trigeminal and vagus nerves, and activate stress responsive regions including hypothalamus; and 2) the contribution of sympathetic and HPA-axis activation in mediating systemic homeostatic metabolic and immune effects of ozone in various organs. The potential contribution of chronic environmental stress in cardiovascular, neurological, reproductive and metabolic diseases, and the knowledge gaps are also discussed. This article is part of a Special Issue entitled Air Pollution, edited by Wenjun Ding, Andrew J. Ghio and Weidong Wu. Published by Elsevier B.V.

  14. Cytoprotective Effects of Pumpkin (Cucurbita Moschata) Fruit Extract against Oxidative Stress and Carbonyl Stress.

    Science.gov (United States)

    Shayesteh, Reyhaneh; Kamalinejad, Mohammad; Adiban, Hasan; Kardan, Azin; Keyhanfar, Fariborz; Eskandari, Mohammad Reza

    2017-10-01

    Background Diabetes mellitus is a chronic endocrine disorder that is associated with significant mortality and morbidity due to microvascular and macrovascular complications. Diabetes complications accompanied with oxidative stress and carbonyl stress in different organs of human body because of the increased generation of free radicals and impaired antioxidant defense systems. In the meantime, reactive oxygen species (ROS) and reactive carbonyl species (RCS) have key mediatory roles in the development and progression of diabetes complications. Therapeutic strategies have recently focused on preventing such diabetes-related abnormalities using different natural and chemical compounds. Pumpkin ( Cucurbita moschata ) is one of the most important vegetables in the world with a broad-range of pharmacological activities such as antihyperglycemic effect. Methods In the present study, the cytoprotective effects of aqueous extract of C. moschata fruit on hepatocyte cytotoxicity induced by cumene hydroperoxide (oxidative stress model) or glyoxal (carbonylation model) were investigated using freshly isolated rat hepatocytes. Results The extract of C. moschata (50 μg/ml) excellently prevented oxidative and carbonyl stress markers, including hepatocyte lysis, ROS production, lipid peroxidation, glutathione depletion, mitochondrial membrane potential collapse, lysosomal damage, and cellular proteolysis. In addition, protein carbonylation was prevented by C. moschata in glyoxal-induced carbonyl stress. Conclusion It can be concluded that C. moschata has cytoprotective effects in oxidative stress and carbonyl stress models and this valuable vegetable can be considered as a suitable herbal product for the prevention of toxic subsequent of oxidative stress and carbonyl stress seen in chronic hyperglycemia. © Georg Thieme Verlag KG Stuttgart · New York.

  15. Effect of the weld joint configuration on stressed components, residual stresses and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Cevik, Bekir; Oezer, Alpay; Oezcatalbas, Yusuf [Gazi Univ., Ankara (Turkey)

    2014-03-01

    The effect of the weld joint configuration on components has been studied, which are under service loads, under repair or construction and the residual stresses as well as the mechanical properties of the joint have been determined. For this purpose, a horizontal positioned tensile testing device and a semi-automatic MIG welding machine have been used and then the weld joints of the plates were subjected to different elastic stresses. When the temperature of the joined elements decreased to room temperature, applied elastic stresses were released. By this means, the effects of the existing tensile stresses in the joined parts and the tensile stresses created by the welding processes were investigated. The tensile stresses occurring in the joined elements were determined by using the photo-elasticity analysis method and the hole-drilling method. Also, tensile-shear tests were applied in order to determine the effect of permanent tensile loads on the mechanical properties of the joint. Experimental results showed that the application of corner welded lap joints for components under tensile loading significantly decrease the shear strength and yielding capacities of the joint. (orig.)

  16. Changes in polyphenol and sugar concentrations in wild type and genetically modified Nicotiana langsdorffii Weinmann in response to water and heat stress.

    Science.gov (United States)

    Ancillotti, Claudia; Bogani, Patrizia; Biricolti, Stefano; Calistri, Elisa; Checchini, Leonardo; Ciofi, Lorenzo; Gonnelli, Cristina; Del Bubba, Massimo

    2015-12-01

    In this study wild type Nicotiana langsdorffii plants were genetically transformed by the insertion of the rat gene (gr) encoding the glucocorticoid receptor or the rolC gene and exposed to water and heat stress. Water stress was induced for 15 days by adding 20% PEG 6000 in the growth medium, whereas the heat treatment was performed at 50 °C for 2 h, after that a re-growing capability study was carried out. The plant response to stress was investigated by determining electrolyte leakage, dry weight biomass production and water content. These data were evaluated in relation to antiradical activity and concentrations of total polyphenols, selected phenolic compounds and some soluble sugars, as biochemical indicators of metabolic changes due to gene insertion and/or stress treatments. As regards the water stress, the measured physiological parameters evidenced an increasing stress level in the order rolC < gr < WT plants (e.g. about 100% and 50% electrolyte leakage increase in WT and gr samples, respectively) and complied with the biochemical pattern, which consisted in a general decrease of antiradical activity and phenolics, together with an increase in sugars. As regard heat stress, electrolyte leakage data were only in partial agreement with the re-growing capability study. In fact, according to this latter evaluation, gr was the genotype less affected by the heat shock. In this regard, sugars and especially phenolic compounds are informative of the long-term effects due to heat shock treatment. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  17. Effects of stress on nursing integrity.

    Science.gov (United States)

    McIntosh, Bryan; Sheppy, Bruce

    This article looks at the relationship between stress, nursing integrity and patient care. It has been argued that the professional integrity of nurses has been eroded and consequently they have become more susceptible to anxiety, stress and exhaustion, potentially affecting care delivery. The authors suggest that the goal of providing high professional standards is threatened by increased service demands, and there is therefore a need for nurses to develop effective coping strategies to manage stress resulting from competing tensions in the workplace.

  18. Adverse effects of stress on microbiota

    Science.gov (United States)

    The complex communities of microorganisms that colonize the gastrointestinal tract impact the health status of an animal. The health of an animal as well as production traits are also affected by exposure to stress. The aim of present study was to evaluate the effects of dehorning stress on the gut ...

  19. Nitrogen nutrition and drought hardening exert opposite effects on the stress tolerance of Pinus pinea L. seedlings.

    Science.gov (United States)

    Villar-Salvador, Pedro; Peñuelas, Juan L; Jacobs, Douglass F

    2013-02-01

    Functional attributes determine the survival and growth of planted seedlings in reforestation projects. Nitrogen (N) and water are important resources in the cultivation of forest species, which have a strong effect on plant functional traits. We analyzed the influence of N nutrition on drought acclimation of Pinus pinea L. seedlings. Specifically, we addressed if high N fertilization reduces drought and frost tolerance of seedlings and whether drought hardening reverses the effect of high N fertilization on stress tolerance. Seedlings were grown under two N fertilization regimes (6 and 100 mg N per plant) and subjected to three drought-hardening levels (well-watered, moderate and strong hardening). Water relations, gas exchange, frost damage, N concentration and growth at the end of the drought-hardening period, and survival and growth of seedlings under controlled xeric and mesic outplanting conditions were measured. Relative to low-N plants, high-N plants were larger, had higher stomatal conductance (27%), residual transpiration (11%) and new root growth capacity and closed stomata at higher water potential. However, high N fertilization also increased frost damage (24%) and decreased plasmalemma stability to dehydration (9%). Drought hardening reversed to a great extent the reduction in stress tolerance caused by high N fertilization as it decreased frost damage, stomatal conductance and residual transpiration by 21, 31 and 24%, respectively, and increased plasmalemma stability to dehydration (8%). Drought hardening increased tissue non-structural carbohydrates and N concentration, especially in high-fertilized plants. Frost damage was positively related to the stability of plasmalemma to dehydration (r = 0.92) and both traits were negatively related to the concentration of reducing soluble sugars. No differences existed between moderate and strong drought-hardening treatments. Neither N nutrition nor drought hardening had any clear effect on seedling

  20. Effects of Humic Acid on the Germination Traits of Pumpkin Seeds under Cadmium Stress

    Directory of Open Access Journals (Sweden)

    Maasoumeh ASADI

    2013-12-01

    Full Text Available The study tackled the effect of humic acid and cadmium concentrations on the pumpkin seed germination characteristics throughout were studied. Treatments were cadmium concentrations on three levels: 0, 100 and 200 ppm and humic acid concentration of 0, 100, 200, 300 and 400 mg lit-1. Results showed that interaction of humic acid and cadmium was not significant on germination traits, but there was a significant effect on seedling growth indexes. Radicle and plumule length increased by 86 and 192% in comparison with control, of the mixture of 200 ppm cadmium and 300 mg lit-1 of humic acid. Cadmium had stimulatory effect on radicle and cotyledon dry weight and the highest values obtained with 200 ppm in mixture with 200 mg lit-1 of humic acid. Also, maximum plumule dry weight was recorded in 200 ppm cadmium and 300 mg lit-1 of humic acid. The highest of indexes were observed of 200 ppm cadmium and 400 mg lit-1 humic acid. In conclusion, the humic acid had detoxifying effect on cadmium stress in the culture and responded antagonistically against cadmium, but it seems that these concentrations of cadmium are low for the pumpkin seed and can be increased in order to reach the toxicity level.

  1. Oxidative stress and antioxidant responses to increasing concentrations of trivalent chromium in the Andean crop species Chenopodium quinoa Willd.

    Science.gov (United States)

    Scoccianti, Valeria; Bucchini, Anahi E; Iacobucci, Marta; Ruiz, Karina B; Biondi, Stefania

    2016-11-01

    Quinoa (Chenopodium quinoa Willd), an ancient Andean seed crop, exhibits exceptional nutritional properties and resistance to abiotic stress. The species' tolerance to heavy metals has, however, not yet been investigated nor its ability to take up and translocate chromium (Cr). This study aimed to investigate the metabolic adjustments occurring upon exposure of quinoa to several concentrations (0.01-5mM) of CrCl3. Young hydroponically grown plants were used to evaluate Cr uptake, growth, oxidative stress, and other biochemical parameters three and/or seven days after treatment. Leaves accumulated the lowest amounts of Cr, while roots and stems accumulated the most at low and at high metal concentrations, respectively. Fresh weight and photosynthetic pigments were reduced only by the higher Cr(III) doses. Substantially increased lipid peroxidation, hydrogen peroxide, and proline levels were observed only with 5mM Cr(III). Except for a significant decrease at day 7 with 5mM Cr(III), total polyphenols and flavonoids maintained control levels in Cr(III)-treated plants, whereas antioxidant activity increased in a dose-dependent manner. Maximum polyamine accumulation was observed in 1mM CrCl3-treated plants. Even though α- and γ-tocopherols also showed enhanced levels only with the 1mM concentration, tyrosine aminotransferase (TAT, EC 2.6.1.5) activity increased under Cr(III) treatment in a dose- and time-dependent manner. Taken together, results suggest that polyamines, tocopherols, and TAT activity could contribute to tolerance to 1mM Cr(III), but not to the highest concentration that, instead, generated oxidative stress. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Stress corrosion cracking of X80 pipeline steel exposed to high pH solutions with different concentrations of bicarbonate

    Science.gov (United States)

    Fan, Lin; Du, Cui-wei; Liu, Zhi-yong; Li, Xiao-gang

    2013-07-01

    Susceptibilities to stress corrosion cracking (SCC) of X80 pipeline steel in high pH solutions with various concentrations of HCO{3/-} at a passive potential of -0.2 V vs. SCE were investigated by slow strain rate tensile (SSRT) test. The SCC mechanism and the effect of HCO{3/-} were discussed with the aid of electrochemical techniques. It is indicated that X80 steel shows enhanced susceptibility to SCC with the concentration of HCO{3/-} increasing from 0.15 to 1.00 mol/L, and the susceptibility can be evaluated in terms of current density at -0.2 V vs. SCE. The SCC behavior is controlled by the dissolution-based mechanism in these circumstances. Increasing the concentration of HCO{3/-} not only increases the risk of rupture of passive films but also promotes the anodic dissolution of crack tips. Besides, little susceptibility to SCC is found in dilute solution containing 0.05 mol/L HCO{3/-} for X80 steel. This can be attributed to the inhibited repassivation of passive films, manifesting as a more intensive dissolution in the non-crack tip areas than at the crack tips.

  3. When does stress help or harm? The effects of stress controllability and subjective stress response on stroop performance.

    Science.gov (United States)

    Henderson, Roselinde K; Snyder, Hannah R; Gupta, Tina; Banich, Marie T

    2012-01-01

    The ability to engage in goal-directed behavior despite exposure to stress is critical to resilience. Questions of how stress can impair or improve behavioral functioning are important in diverse settings, from athletic competitions to academic testing. Previous research suggests that controllability is a key factor in the impact of stress on behavior: learning how to control stressors buffers people from the negative effects of stress on subsequent cognitively demanding tasks. In addition, research suggests that the impact of stress on cognitive functioning depends on an individual's response to stressors: moderate responses to stress can lead to improved performance while extreme (high or low) responses can lead to impaired performance. The present studies tested the hypothesis that (1) learning to behaviorally control stressors leads to improved performance on a test of general executive functioning, the color-word Stroop, and that (2) this improvement emerges specifically for people who report moderate (subjective) responses to stress. Experiment 1: Stroop performance, measured before and after a stress manipulation, was compared across groups of undergraduate participants (n = 109). People who learned to control a noise stressor and received accurate performance feedback demonstrated reduced Stroop interference compared with people exposed to uncontrollable noise stress and feedback indicating an exaggerated rate of failure. In the group who learned behavioral control, those who reported moderate levels of stress showed the greatest reduction in Stroop interference. In contrast, in the group exposed to uncontrollable events, self-reported stress failed to predict performance. Experiment 2: In a second sample (n = 90), we specifically investigated the role of controllability by keeping the rate of failure feedback constant across groups. In the group who learned behavioral control, those who reported moderate levels of stress showed the greatest Stroop

  4. European bond markets: do illiquidity and concentration aggravate price shocks?

    NARCIS (Netherlands)

    Boermans, M.A.; Frost, Jon; Steins Bisschop, Sophie

    2016-01-01

    We study the effects of market liquidity and ownership concentration of European bonds on price volatility during periods of market stress. Specifically, using security-by-security data from euro area investors we examine if market illiquidity and concentrated holdings explain the large price shocks

  5. Pro-inflammatory effects and oxidative stress in lung macrophages and epithelial cells induced by ambient particulate matter.

    Science.gov (United States)

    Michael, S; Montag, M; Dott, W

    2013-12-01

    The objective of this study was to compare the toxicological effects of different source-related ambient PM10 samples in regard to their chemical composition. In this context we investigated airborne PM from different sites in Aachen, Germany. For the toxicological investigation human alveolar epithelial cells (A549) and murine macrophages (RAW264.7) were exposed from 0 to 96 h to increasing PM concentrations (0-100 μg/ml) followed by analyses of cell viability, pro-inflammatory and oxidative stress responses. The chemical analysis of these particles indicated the presence of 21 elements, water-soluble ions and PAHs. The toxicological investigations of the PM10 samples demonstrated a concentration- and time-dependent decrease in cell viability and an increase in pro-inflammatory and oxidative stress markers. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Effect of Salt Stress on Growth and Antioxidant Enzymes in Two Cultivars of Maize (Zea Mays L.)

    International Nuclear Information System (INIS)

    Saddiqe, Z.; Javeria, S; Khalid, H; Farooq, A.

    2016-01-01

    The effect of various concentrations of NaCl (50, 75, 100, 125, 150 mM ) was determined on the growth and biochemistry of two maize (Zea mays L.) cultivars (Pioneer X8F932 and DK -C61-42). Seed germination under salt stress conditions was more affected in cv. Pioneer X8F932 than cv. DK-C61-42. A significant reduction (p<0.05) in root and shoot growth was observed at 100, 125 and 150 mM salt concentrations in both the cultivars. Salt stress also caused a decrease in fresh weight of seedlings in a dose dependant manner (p=0.05). Among the two cultivars DK-C61-42 showed better tolerance towards salt stress (tolerance index = 105.4 at 75 mM) compared to Pioneer X8F932 (tolerance index = 76 at 50 mM). Total soluble protein content increased in both the cultivars under salt stress in a dose dependant manner with maximum protein content at 150 mM (6.004 mg/g tissue in DK-C61-42 and 7.375 mg/g tissue in cv. Pioneer X8F932). In DK-C61-42 highest peroxidase activity was at 125 mM (0.017 mg/g tissue) while in Pioneer X8F932 highest peroxidase activity was at 50 mM (0.006 mg/g tissue). The difference in enzyme activity between control and salt treated seedlings was significant (p<0.05). The catalase activity decreased under salt stress conditions in case of DK-C61-42 while an increase in activity of the enzyme was observed in Pioneer X8F932 at high salt concentrations. Among the two cultivars DK-C61-42 was better adapted towards salinity stress. (author)

  7. The salicylic acid effect on the tomato (lycopersicum esculentum Mill. germination, growth and photosynthetic pigment under salinity stress (NaCl

    Directory of Open Access Journals (Sweden)

    Shahba Zahra

    2010-09-01

    Full Text Available Soil salinity is a serious environmental problem that has negative effect on plant growth, production and photosynthesis. Fresh and dry plant weights decreases with salinity treatments. The very important role of salicylic acid (SA in response to different stress and modification and decline damages due to stresses has established in different studies. In this research tomato seeds planted in pots containing perlite in a growth chamber under controlled conditions of 27±2°c and 23±2°c temperature , 16h lightness and 8h darkness respectively, 15 Klux light intensity and 75% humidity; NaCl concentration of 0, 25, 50, 75 and 100 mM and salicylic acid concentration of 0, 0.5, 1 and 1.5 mM were used in the form of factorial experiment in a complete randomized design (CRD. Results show that germination was decreased with salinity increasing. At low levels of salinity, SA leads to decrease in germination and had no effect in high levels of salinity. The length of shoot were not effected by salinity but decrease with increase in SA concentration. Low salinity concentrations led to significant increase in root length and high concentrations don’t have significant difference with control. SA also had no effect on it. The highest amount of a, b, c and total chlorophyll and carotenoid was show in 50 mM salinity levels.

  8. Life span effects of Hypericum perforatum extracts on Caenorhabditis elegans under heat stress.

    Science.gov (United States)

    Kılıçgün, Hasan; Göksen, Gülden

    2012-10-01

    The beneficial effects of antioxidants in plants are mainly extrapolated from in vitro studies or short-term dietary supplementation studies. Due to cost and duration, relatively little is known about whether dietary antioxidants are beneficial in whole animals' life span or not. To address this question, under heat stress (35°C), Hypericum perforatum was extracted with petroleum ether and the nematodes Caenorhabditis elegans exposed to three different extract concentrations (1mg/mL, 0.1mg/mL, 0.01mg/mL) of H. perforatum. We report that Hypericum perforatum extracts did not increase life span and slow aging related increase in C. elegans. Moreover, one fraction (1mg/mL) increased declines of C. elegans life span and thermotolerance. Given this mounting evidence for life span role of H. perforatum in the presence of heat stress in vivo, the question whether H. perforatum acts as a prooxidant or an antioxidant in vivo under heat stress arises.

  9. Effect of N-acetylcysteine treatment on oxidative stress and inflammation after severe burn.

    Science.gov (United States)

    Csontos, C; Rezman, B; Foldi, V; Bogar, L; Drenkovics, L; Röth, E; Weber, G; Lantos, J

    2012-05-01

    Oxidative stress and inflammation generate edema in burns. The aim of our study was to assess effect of N-acetylcysteine (NAC) on oxidative stress, inflammation, fluid requirement, multiple organ dysfunction (MOD) score and vasoactive drug requirement. In this study 15 patients were on standard therapy, whereas for other 15 patients NAC was supplemented. Blood samples were taken on admission and on the next five consecutive mornings. Levels of malondialdehyde, protein sulfhydril (PSH) groups, reduced gluthation (GSH), activity of myeloperoxidase, catalase and superoxide dismutase enzymes and induced free radical generating capacity were measured as well as concentrations of TNF-α, IL-6, IL-8, and IL-10. MOD score, use of vasopressor agents and fluid utilisation were recorded daily. NAC treatment increased GSH level on days 4-5 (ptreatment is associated with a diminished oxidative stress reflected in preserved antioxidant levels, lower inflammation mirrored in lower interleukin levels and less vasopressor requirement. Copyright © 2011 Elsevier Ltd and ISBI. All rights reserved.

  10. Effects of maternal cortisol treatment on offspring size, responses to stress, and anxiety-related behavior in wild largemouth bass (Micropterus salmoides).

    Science.gov (United States)

    Redfern, Julia C; Cooke, Steven J; Lennox, Robert J; Nannini, Michael A; Wahl, David H; Gilmour, Kathleen M

    2017-10-15

    Cortisol, the main glucocorticoid stress hormone in teleost fish, is of interest as a mediator of maternal stress on offspring characteristics because it plays an organizational role during early development. The present study tested the hypothesis that maternal exposure to cortisol treatment prior to spawn affects offspring phenotype using wild largemouth bass (Micropterus salmoides). Baseline and stress-induced cortisol concentrations, body size (i.e. length and mass), and behavior (i.e. anxiety, exploration, boldness, and aggression) were assessed at different offspring life-stages and compared between offspring of control and cortisol-treated females. Cortisol administration did not affect spawning success or timing, nor were whole-body cortisol concentrations different between embryos from cortisol-treated and control females. However, maternal cortisol treatment had significant effects on offspring stress responsiveness, mass, and behavior. Compared to offspring of control females, offspring of cortisol-treated females exhibited larger mass right after hatch, and young-of-the-year mounted an attenuated cortisol response to an acute stressor, and exhibited less thigmotaxic anxiety, exploratory behavior, boldness and aggression. Thus, offspring phenotype was affected by elevated maternal cortisol levels despite the absence of a significant increase in embryo cortisol concentrations, suggesting that a mechanism other than the direct deposition of cortisol into eggs mediates effects on offspring. The results of the present raise questions about the mechanisms through which maternal stress influences offspring behavior and physiology, as well as the impacts of such phenotypic changes on offspring fitness. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Markers of Oxidative Stress in Dogs with Myxomatous Mitral Valve Disease are Influenced by Sex, Neuter Status, and Serum Cholesterol Concentration

    DEFF Research Database (Denmark)

    Reimann, M J; Häggström, J; Møller, J E

    2017-01-01

    -tocopherol [P = .003]) was associated with body condition score (BCS), but the association disappeared when cholesterol was included in the analyses. All markers of oxidative stress (MDA, oxLDL, and vitamin E) were positively associated with serum cholesterol concentration (P ≤ .04), but none were associated...... with clinical stage of MMVD. CONCLUSIONS: In conclusion, markers of oxidative stress are associated with sex, BCS, neuter status, and cholesterol. The results cannot confirm a relationship between oxidative stress and clinical stage of the disease in dogs with MMVD....

  12. Dose-Response Effect of Tualang Honey on Postprandial Antioxidant Activity and Oxidative Stress in Female Athletes: A Pilot Study.

    Science.gov (United States)

    Ahmad, Nur Syamsina; Abdul Aziz, Azlina; Kong, Kin Weng; Hamid, Mohamad Shariff A; Cheong, Jadeera Phaik Geok; Hamzah, Sareena Hanim

    2017-12-01

    Tualang honey (TH) contains antioxidants such as ascorbic acid, phenolic acids, and flavonoids that may be protective against oxidative stress of exercise. The aim of this study was to examine the postprandial antioxidant activity and oxidative stress after ingestion of high and low dosages of TH in female athletes. Twenty female athletes (aged 21.3 [2.1] years; body weight [BW] 54.1 [5.7] kg) were randomly assigned into two groups and consumed either 1.5 g/kg BW TH (high honey; HH; n = 10) or 0.75 g/kg BW TH (low honey; LH; n = 10). Blood sample was collected at fasting and at 0.5, 1, 2, and 3 h after TH consumption. Plasma was analyzed for total phenolic content (TPC), antioxidant activity (ferric reducing antioxidant power [FRAP]), and oxidative stress biomarkers (malondialdehyde [MDA] and reactive oxygen species [ROS]). The 3-h area under the curve (AUC) for MDA was significantly lower in the LH group compared with HH group, suggesting less oxidative stress in the LH group. However, the AUCs for TPC, FRAP, and ROS were not affected by the dosages. The concentrations of TPC and FRAP increased from baseline to 2 and 1 h after TH consumption, respectively, and concentrations returned toward baseline at 3 h in both LH and HH groups. MDA concentration significantly decreased (p antioxidant activity and suppressing oxidative stress in female athletes. The time-course effect of TH that provides optimal antioxidant activity and oxidative stress protection was between 1 and 2 h after its consumption.

  13. Effects of exogenous epibrassinolide on photosynthetic characteristics in tomato (Lycopersicon esculentum Mill) seedlings under weak light stress.

    Science.gov (United States)

    Wang, Ming; Jiang, Weijie; Yu, Hongjun

    2010-03-24

    The effects of three concentrations (0.1, 0.01, 0.001 mg/kg) of exogenous 24-epibrassinolide on leaf photosynthesis, chlorophyll content, chlorophyll fluorescence, and parameters of light response curve in tomato seedlings under 150 micromol x m(-2) x s(-1) weak light stress were studied, with two tomato cultivars, 'Zhongza9', tolerant, and 'Zhongshu6', sensitive to weak light stress. The results showed that the net photosynthetic rate (Pn), maximal photochemical quantum efficiency of PSII (Fv/Fm), light saturation point (LSP), and dark respiration rate (Rd) decreased remarkably under weak light, but the chlorophyll content, especially chlorophyll b (chlb) content, increased obviously compared with normal light intensity control. However, exogenous 24-epibrassinolide alleviated the decrease of leaf Pn and Fv/Fm and induced the further increase of chlb content as well as the further decrease of Rd and chla/chlb under weak light stress, which indicated that exogenous 24-epibrassinolide could enhance plant tolerance to weak light and diminish damage from weak light. However, the optimum concentrations were different between the two cultivars; 0.1 mg/kg 24-epibrassinolide showed the best induction effects in 'Zhongshu6', and the best level for 'Zhongza9' was 0.01 mg/kg 24-epibrassinolide.

  14. Pro-inflammatory effects and oxidative stress in lung macrophages and epithelial cells induced by ambient particulate matter

    International Nuclear Information System (INIS)

    Michael, S.; Montag, M.; Dott, W.

    2013-01-01

    The objective of this study was to compare the toxicological effects of different source-related ambient PM10 samples in regard to their chemical composition. In this context we investigated airborne PM from different sites in Aachen, Germany. For the toxicological investigation human alveolar epithelial cells (A549) and murine macrophages (RAW264.7) were exposed from 0 to 96 h to increasing PM concentrations (0–100 μg/ml) followed by analyses of cell viability, pro-inflammatory and oxidative stress responses. The chemical analysis of these particles indicated the presence of 21 elements, water-soluble ions and PAHs. The toxicological investigations of the PM10 samples demonstrated a concentration- and time-dependent decrease in cell viability and an increase in pro-inflammatory and oxidative stress markers. -- Highlights: ► The study compares the toxicological effects of different source-related particles with regard to their chemical composition. ► The chemical characterization of the coarse particles revealed clear differences in elemental, TC and PAH composition. ► Equal mass concentrations of urban traffic and rural PM caused different toxicological responses. ► The observations confirm the hypothesis that particle composition, as well as origin, influence the PM-induced toxicity. -- The toxicological responses of lung epithelial cells and macrophages differ significantly after an exposure to equal mass concentrations of urban traffic and rural PM

  15. DPP4 deficiency exerts protective effect against H2O2 induced oxidative stress in isolated cardiomyocytes.

    Directory of Open Access Journals (Sweden)

    Hui-Chun Ku

    Full Text Available Apart from the antihyperglycemic effects, DPP4 inhibitors and GLP-1 molecules are involved in the preservation of cardiac functions. We have demonstrated that DPP4-deficient rats possess resistance to endotoxemia and ischemia/reperfusion stress. However, whether the decrease of DPP4 activity simply augmented the GLP-1 signaling or that such decrease resulted in a change of cellular function remain unclear. Accordingly, we investigated the responses of H(2O(2-induced oxidative stress in adult wild-type and DPP4-deficient rats isolated cardiomyocytes. The coadministration of GLP-1 or DPP4 inhibitor was also performed to define the mechanisms. Cell viability, ROS concentration, catalase activity, glucose uptake, prosurvival, proapoptotic signaling, and contractile function were examined after cells exposed to H(2O(2. DPP4-deficient cardiomyocytes were found to be resistant to H(2O(2-induced cell death via activating AKT signaling, enhancing glucose uptake, preserving catalase activity, diminishing ROS level and proapoptotic signaling. GLP-1 concentration-dependently improved cell viability in wild-type cardiomyocyte against ROS stress, and the ceiling response concentration (200 nM was chosen for studies. GLP-1 was shown to decrease H(2O(2-induced cell death by its receptor-dependent AKT pathway in wild-type cardiomyocytes, but failed to cause further activation of AKT in DPP4-deficient cardiomyocytes. Acute treatment of DPP4 inhibitor only augmented the protective effect of low dose GLP-1, but failed to alter fuel utilization or ameliorate cell viability in wild-type cardiomyocytes after H(2O(2 exposure. The improvement of cell viability after H(2O(2 exposure was correlated with the alleviation of cellular contractile dysfunction in both DPP4-deficient and GLP-1 treated wild-type cardiomyocytes. These findings demonstrated that GLP-1 receptor-dependent pathway is important and exert protective effect in wild-type cardiomyocyte. Long term loss of

  16. Effects of two-hour exposure to environmental and high concentrations of methylmercury on the transcriptome of the macrophyte Elodea nuttallii.

    Science.gov (United States)

    Beauvais-Flück, Rebecca; Slaveykova, Vera I; Cosio, Claudia

    2018-01-01

    The effects of two methylmercury (CH 3 Hg + , MeHg) concentrations, representative of environmental level and extreme contamination, were investigated on the macrophyte Elodea nuttallii during a 2h-exposure combining transcriptomic (RNA-Seq), physiological endpoints (pigment contents, activity of anti-oxidative stress enzymes) and bioaccumulation. Exposure to MeHg induced the up- and down-regulation of numerous genes (4389 and 16853 for 10ngL -1 and 10μgL -1 MeHg exposure, respectively) involved in sugar, amino acid and secondary metabolism (e.g. cinnamic acid, flavonoids) at both concentrations. Genes coding for photosynthesis, membrane integrity, metal homeostasis, water transport and anti-oxidative enzymes were additionally up- and down-regulated at the higher concentration. At the physiological level, exposure to both MeHg concentrations resulted in a strong increase of anthocyanin content in shoots. Chlorophyll content and antioxidant enzyme activities were unchanged. The data suggest that the macrophyte was able to efficiently cope with the stress resulting from MeHg exposure, possibly by using anthocyanin as anti-oxidant and S-rich amino acids (such as cysteine and methionine) as chelators. Transcriptomics analysis enabled gaining novel insights on molecular effects of MeHg in primary producers, which are one of the main entry pathway of hazardous MeHg in aquatic food webs. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. High Pb concentration stress on Typha latifolia growth and Pb removal in microcosm wetlands.

    Science.gov (United States)

    Han, Jianqiu; Chen, Fengzhen; Zhou, Yumei; Wang, Chaohua

    2015-01-01

    When constructed wetlands are used to treat high-Pb wastewater, Pb may become a stress to wetland plants, which subsequently reduces treatment performance and the other ecosystem services. To facilitate the design and operation of constructed wetlands for treatment of Pb-rich wastewater, we investigated the irreversible inhibitory level of Pb for Typha latifolia through experiments in microcosm wetlands. Seven horizontal subsurface flow constructed wetlands were built with rectangular plastic tanks and packed with marble chips and sand. All wetlands were transplanted with nine stems of Typha latifolia each. The wetlands were batch operated in a greenhouse with artificial wastewater (10 L each) for 12 days. Influent to the seven wetlands had different concentrations of Pb: 0 mg/L, 10 mg/L, 25 mg/L, 50 mg/L, 100 mg/L, 200 mg/L, and 500 mg/L, respectively. The results suggested that leaf chlorophyll relative content, relative growth rate, photosynthetic characteristics, activities of superoxide dismutase, peroxidase, and content of malondialdehyde were not affected when initial Pb concentration was at 100 mg/L and below. But when initial Pb concentration was above 100 mg/L, all of them were seriously affected. We conclude that high Pb concentrations wastewater could inhibit the growth of Typha latifolia and decrease the removal rate of wetlands.

  18. Effects of mindfulness-based stress reduction on depression, anxiety, stress and mindfulness in Korean nursing students.

    Science.gov (United States)

    Song, Yeoungsuk; Lindquist, Ruth

    2015-01-01

    Nursing students often experience depression, anxiety, stress and decreased mindfulness which may decrease their patient care effectiveness. Mindfulness-based stress reduction (MBSR) effectively reduced depression, anxiety and stress, and increased mindfulness in previous research with other populations, but there is sparse evidence regarding its effectiveness for nursing students in Korea. To examine the effects of MBSR on depression, anxiety, stress and mindfulness in Korean nursing students. A randomized controlled trial. Fifty (50) nursing students at KN University College of Nursing in South Korea were randomly assigned to two groups. Data from 44 students, MBSR (n=21) and a wait list (WL) control (n=23) were analyzed. The MBSR group practiced mindfulness meditation for 2 h every week for 8 weeks. The WL group did not receive MBSR intervention. Standardized self-administered questionnaires of depression, anxiety, stress and mindfulness were administered at the baseline prior to the MBSR program and at completion (at 8 weeks). Compared with WL participants, MBSR participants reported significantly greater decreases in depression, anxiety and stress, and greater increase in mindfulness. A program of MBSR was effective when it was used with nursing students in reducing measures of depression, anxiety and stress, and increasing their mindful awareness. MBSR shows promise for use with nursing students to address their experience of mild depression, anxiety and stress, and to increase mindfulness in academic and clinical work, warranting further study. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Antidepressant effects of exercise are produced via suppression of hypocretin/orexin and melanin-concentrating hormone in the basolateral amygdala.

    Science.gov (United States)

    Kim, Tae-Kyung; Kim, Ji-Eun; Park, Jin-Young; Lee, Jung-Eun; Choi, Juli; Kim, Hannah; Lee, Eun-Hwa; Kim, Seung-Woo; Lee, Ja-Kyeong; Kang, Hyun-Sik; Han, Pyung-Lim

    2015-07-01

    Physical exercise is considered beneficial in the treatment of depression, but the underlying mechanism is not clearly understood. In the present study, we investigated the mechanism regulating antidepressant effects of exercise by focusing on the role of the amygdala using a well-defined animal model of depression. C57BL/6 mice treated with repeated restraint showed depression-like behaviors, which was counteracted by post-stress treatment with physical exercise. The two neuropeptides hypocretin/orexin (Hcrt/Orx) and melanin-concentrating hormone (MCH) were transcriptionally upregulated in the BLA after repeated stress, and their enhanced expression was downregulated by treatment with exercise, mirroring stress-induced depression-like behaviors and their reversal by exercise. Stereotaxic injection of either Hcrt/Orx peptide or MCH peptide within the BLA commonly increased phospho-CaMKIIα level and produced depression-like behaviors, mimicking the neural states in the BLA of mice subjected to repeated stress. In contrast, siRNA-mediated suppression of Hcrt/Orx or MCH in the BLA blocked stress-induced depression-like behaviors. Furthermore, siRNA-mediated inhibition of CaMKIIα in the BLA also counteracted stress-induced depression-like behaviors. Local injection of Hcrt/Orx peptide or MCH peptide within the BLA in exercise-treated animals blocked antidepressant-like effects of exercise. Together these results suggest that exercise produces antidepressant effects via suppression of Hcrt/Orx and MCH neural systems in the BLA. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Stress in telephone helpline nurses is associated with failures of concentration, attention and memory, and with more conservative referral decisions.

    Science.gov (United States)

    Allan, Julia L; Farquharson, Barbara; Johnston, Derek W; Jones, Martyn C; Choudhary, Carolyn J; Johnston, Marie

    2014-05-01

    Nurses working for telephone-based medical helplines must maintain attentional focus while quickly and accurately processing information given by callers to make safe and appropriate treatment decisions. In this study, both higher levels of general occupational stress and elevated stress levels on particular shifts were associated with more frequent failures of attention, memory, and concentration in telephone nurses. Exposure to a stressful shift was also associated with a measurable increase in objectively assessed information-processing errors. Nurses who experienced more frequent cognitive failures at work made more conservative decisions, tending to refer patients on to other health professionals more often than other nurses. As stress is associated with cognitive performance decrements in telephone nursing, stress-reduction interventions could improve the quality and safety of care that callers to medical helplines receive. © 2013 The British Psychological Society.

  1. Fish oil consumption prevents glucose intolerance and hypercorticosteronemy in footshock-stressed rats

    Directory of Open Access Journals (Sweden)

    Spadari-Bratfisch Regina C

    2011-05-01

    Full Text Available Abstract Background Environmental stress plays an important role in the development of glucose intolerance influencing lipid and glucose metabolism through sympathetic nervous system, cytokines and hormones such as glucocorticoids, catecholamines and glucagon. Otherwise, fish oil prevents glucose intolerance and insulin resistance. Although the mechanisms involved are not fully understood, it is known that sympathetic and HPA responses are blunted and catecholamines and glucocorticoids concentrations can be modulated by fish consumption. The aim of the present study was to evaluate whether fish oil, on a normal lipidic diet: 1 could prevent the effect of footshock-stress on the development of glucose intolerance; 2 modified adiponectin receptor and serum concentration; and 3 also modified TNF-α, IL-6 and interleukin-10 (IL-10 levels in adipose tissue and liver. The study was performed in thirty day-old male Wistar randomly assigned into four groups: no stressed (C and stressed (CS rats fed with control diet, and no stressed (F and stressed (FS rats fed with a fish oil rich diet. The stress was performed as a three daily footshock stress sessions. Results Body weight, carcass fat and protein content were not different among groups. FS presented a reduction on the relative weight of RET. Basal serum glucose levels were higher in CS and FS but 15 min after glucose load just CS remained with higher levels than other groups. Serum corticosterone concentration was increased in CS, this effect was inhibited in FS. However, 15 min after footshock-stress, corticosterone levels were similar among groups. IL-6 was increased in EPI of CS but fish oil consumption prevented IL-6 increase in FS. Similar levels of TNF-α and IL-10 in RET, EPI, and liver were observed among groups. Adipo R1 protein concentration was not different among groups. Footshock-stress did not modify AdipoR2 concentration, but fish oil diet increases AdipoR2 protein concentration

  2. Silicon improves seed germination and alleviates oxidative stress of bud seedlings in tomato under water deficit stress.

    Science.gov (United States)

    Shi, Yu; Zhang, Yi; Yao, Hejin; Wu, Jiawen; Sun, Hao; Gong, Haijun

    2014-05-01

    The beneficial effects of silicon on plant growth and development under drought have been widely reported. However, little information is available on the effects of silicon on seed germination under drought. In this work, the effects of exogenous silicon (0.5 mM) on the seed germination and tolerance performance of tomato (Solanum lycopersicum L.) bud seedlings under water deficit stress simulated by 10% (w/v) polyethylene glycol (PEG-6000) were investigated in four cultivars ('Jinpengchaoguan', 'Zhongza No.9', 'Houpi L402' and 'Oubao318'). The results showed that the seed germination percentage was notably decreased in the four cultivars under water stress, and it was significantly improved by added silicon. Compared with the non-silicon treatment, silicon addition increased the activities of superoxide dismutase (SOD) and catalase (CAT), and decreased the production of superoxide anion (O2·) and hydrogen peroxide (H2O2) in the radicles of bud seedlings under water stress. Addition of silicon decreased the total phenol concentrations in radicles under water stress, which might contribute to the decrease of peroxidase (POD) activity, as observed in the in vivo and in vitro experiments. The decrease of POD activity might contribute to a less accumulation of hydroxyl radical (·OH) under water stress. Silicon addition also decreased the concentrations of malondialdehyde (MDA) in the radicles under stress, indicating decreased lipid peroxidation. These results suggest that exogenous silicon could improve seed germination and alleviate oxidative stress to bud seedling of tomato by enhancing antioxidant defense. The positive effects of silicon observed in a silicon-excluder also suggest the active involvement of silicon in biochemical processes in plants. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  3. Prenatal exposure to escitalopram and/or stress in rats: a prenatal stress model of maternal depression and its treatment

    Science.gov (United States)

    Bourke, Chase H.; Capello, Catherine F.; Rogers, Swati M.; Yu, Megan L.; Boss-Williams, Katherine A.; Weiss, Jay M.; Stowe, Zachary N.; Owens, Michael J.

    2014-01-01

    Rationale A rigorously investigated model of stress and antidepressant administration during pregnancy is needed to evaluate possible effects on the mother. Objective The objective of this study was to develop a model of clinically relevant prenatal exposure to an antidepressant and stress during pregnancy to evaluate the effects on maternal care behavior. Results Female rats implanted with 28 day osmotic minipumps delivering the SSRI escitalopram throughout pregnancy had serum escitalopram concentrations in a clinically observed range (17-65 ng/mL). A separate cohort of pregnant females exposed to a chronic unpredictable mild stress paradigm on gestational days 10-20 showed elevated baseline (305 ng/mL), and acute stress-induced (463 ng/mL), plasma corticosterone concentrations compared to unstressed controls (109 ng/mL). A final cohort of pregnant dams were exposed to saline (control), escitalopram, stress, or stress and escitalopram to determine the effects on maternal care. Maternal behavior was continuously monitored over the first 10 days post parturition. A reduction of 35% in maternal contact and 11% in nursing behavior was observed due to stress during the light cycle. Licking and grooming behavior was unaffected by stress or drug exposure in either the light or dark cycle. Conclusions These data indicate that: 1) clinically relevant antidepressant treatment during human pregnancy can be modeled in rats using escitalopram; 2) chronic mild stress can be delivered in a manner that does not compromise fetal viability; and 3) neither of these prenatal treatments substantially altered maternal care post parturition. PMID:23436130

  4. Cortisol stress response in post-traumatic stress disorder, panic disorder, and major depressive disorder patients.

    Science.gov (United States)

    Wichmann, Susann; Kirschbaum, Clemens; Böhme, Carsten; Petrowski, Katja

    2017-09-01

    Previous research has focussed extensively on the distinction of HPA-axis functioning between patient groups and healthy volunteers, with relatively little emphasis on a direct comparison of patient groups. The current study's aim was to analyse differences in the cortisol stress response as a function of primary diagnosis of panic disorder (PD), post-traumatic stress disorder (PTSD), and major depressive disorder (MDD). A total of n=30 PD (mean age±SD: 36.07±12.56), n=23 PTSD (41.22±10.17), n=18 MDD patients (39.00±14.93) and n=47 healthy control (HC) individuals (35.51±13.15) participated in this study. All the study participants were female. The Trier Social Stress Test (TSST) was used for reliable laboratory stress induction. Blood sampling accompanied the TSST for cortisol and ACTH assessment. Panic-related, PTSD-specific questionnaires and the Beck Depression Inventory II were handed out for the characterisation of the study groups. Repeated measure ANCOVAs were conducted to test for main effects of time or group and for interaction effects. Regression analyses were conducted to take comorbid depression into account. 26.7% of the PD patients, 43.5% of the PTSD patients, 72.2% of the MDD patients and 80.6% of the HC participants showed a cortisol stress response upon the TSST. ANCOVA revealed a cortisol hypo-responsiveness both in PD and PTSD patients, while no significant group differences were seen in the ACTH concentrations. Additional analyses showed no impact of comorbid depressiveness on the cortisol stress response. MDD patients did not differ in the hormonal stress response neither compared to the HC participants nor to the PD and PTSD patients. Our main findings provide evidence of a dissociation between the cortisol and ACTH concentrations in response to the TSST in PTSD and in PD patients, independent of comorbid depression. Our results further support overall research findings of a cortisol hypo-responsiveness in PD patients. A hypo

  5. The dichotomous effect of chronic stress on obesity

    OpenAIRE

    Razzoli, Maria; Bartolomucci, Alessandro

    2016-01-01

    Obesity and metabolic diseases are linked to chronic stress and low socio-economic status. The mechanistic link between stress and obesity has not been clarified, partly due to the inherent complexity exemplified by the bidirectional effect of stress on eating and body weight. Recent studies focusing on adaptive-thermogenesis and brown adipose tissue (BAT) function support a dichotomous relationship to explain the impact of stress on obesity: stress promotes obesity in the presence of hyperph...

  6. SvO(2)-guided resuscitation for experimental septic shock: effects of fluid infusion and dobutamine on hemodynamics, inflammatory response, and cardiovascular oxidative stress.

    Science.gov (United States)

    Rosário, André Loureiro; Park, Marcelo; Brunialti, Milena Karina; Mendes, Marialice; Rapozo, Marjorie; Fernandes, Denise; Salomão, Reinaldo; Laurindo, Francisco Rafael; Schettino, Guilherme Paula; Azevedo, Luciano Cesar P

    2011-12-01

    The pathogenetic mechanisms associated to the beneficial effects of mixed venous oxygen saturation (SvO(2))-guided resuscitation during sepsis are unclear. Our purpose was to evaluate the effects of an algorithm of SvO(2)-driven resuscitation including fluids, norepinephrine and dobutamine on hemodynamics, inflammatory response, and cardiovascular oxidative stress during a clinically resembling experimental model of septic shock. Eighteen anesthetized and catheterized pigs (35-45 kg) were submitted to peritonitis by fecal inoculation (0.75 g/kg). After hypotension, antibiotics were administered, and the animals were randomized to two groups: control (n = 9), with hemodynamic support aiming central venous pressure 8 to 12 mmHg, urinary output 0.5 mL/kg per hour, and mean arterial pressure greater than 65 mmHg; and SvO(2) (n = 9), with the goals above, plus SvO(2) greater than 65%. The interventions lasted 12 h, and lactated Ringer's and norepinephrine (both groups) and dobutamine (SvO(2) group) were administered. Inflammatory response was evaluated by plasma concentration of cytokines, neutrophil CD14 expression, oxidant generation, and apoptosis. Oxidative stress was evaluated by plasma and myocardial nitrate concentrations, myocardial and vascular NADP(H) oxidase activity, myocardial glutathione content, and nitrotyrosine expression. Mixed venous oxygen saturation-driven resuscitation was associated with improved systolic index, oxygen delivery, and diuresis. Sepsis induced in both groups a significant increase on IL-6 concentrations and plasma nitrate concentrations and a persistent decrease in neutrophil CD14 expression. Apoptosis rate and neutrophil oxidant generation were not different between groups. Treatment strategies did not significantly modify oxidative stress parameters. Thus, an approach aiming SvO(2) during sepsis improves hemodynamics, without any significant effect on inflammatory response and oxidative stress. The beneficial effects associated

  7. DISTRIBUTION OF THE EFFECTS OF BREWING INDUSTRY CONCENTRATION AMONG LARGE AND SMALL COMPANIES OPERATING ON THE POLISH MARKET IN 2004-2011 PERIOD

    Directory of Open Access Journals (Sweden)

    Krzysztof Łobos

    2013-12-01

    Full Text Available Polish beer market is characterised by a high degree of concentration. The market share of Kompania Piwowarska, Grupa Żywiec and Carlsberg Polska is 90%. Many authors stress concentration as an important factor when explaining why various industries are more or less effective or more or less profitable. Firms from concentrated industries report, on average, higher profitability than those in non-concentrated industries. The aim of this paper is to analyse the differences of economic efficiency of large (group I and small (group II entities involved in the production of beer. Evaluation of the effectiveness of the test group of companies was based on selected financial ratios (return on assets, return on sales, inventory turnover, total debt ratio.

  8. Ability of multiaxial fatigue criteria accounting for stress gradient effect for surface defective material

    Directory of Open Access Journals (Sweden)

    Niamchaona Wichian

    2018-01-01

    Full Text Available New high strength steels are widely used nowadays in many industrial areas as in automotive industry. These steels are more resistant and provide higher fatigue limits than latter ones but they are also more sensible to small defects. Natural defects that outcome from metallurgy (as shrinkage, inclusion, void are not considered in this study. We focus on small manufacturing defects such as cutting edge defects generated by punching or other surface defects due to stamping. These defects are harmful on the material fatigue behaviour due to high stress concentration at defects root. They also generate stress gradient that is beneficial from the fatigue strength point of view. This study focusses on the stress gradient (it does not account for the size effect from cylindrical defect on specimen edge. Practically a normal stress gradient is added in multiaxial fatigue criteria formulation. Both critical plane approach and integral approach are involved in the present study. This gradient is calculated from stress states at defects root by using FEM. Criteria fatigue function at N cycles is used to assess the material fatigue strength. Obviously multiaxial fatigue criteria accounting for stress gradient give more precise fatigue functions than criteria that do not consider the gradient influence.

  9. Leptin inhibits and ghrelin augments hypothalamic noradrenaline release after stress.

    Science.gov (United States)

    Kawakami, Akio; Okada, Nobukazu; Rokkaku, Kumiko; Honda, Kazufumi; Ishibashi, Shun; Onaka, Tatsushi

    2008-09-01

    Metabolic conditions affect hypothalamo-pituitary-adrenal responses to stressful stimuli. Here we examined effects of food deprivation, leptin and ghrelin upon noradrenaline release in the hypothalamic paraventricular nucleus (PVN) and plasma adrenocorticotropic hormone (ACTH) concentrations after stressful stimuli. Food deprivation augmented both noradrenaline release in the PVN and the increase in plasma ACTH concentration following electrical footshocks (FSs). An intracerebroventricular injection of leptin attenuated the increases in hypothalamic noradrenaline release and plasma ACTH concentrations after FSs, while ghrelin augmented these responses. These data suggest that leptin inhibits and ghrelin facilitates neuroendocrine stress responses via noradrenaline release and indicate that a decrease in leptin and an increase in ghrelin release after food deprivation might contribute to augmentation of stress-induced ACTH release in a fasting state.

  10. Acute restraint stress induces endothelial dysfunction: role of vasoconstrictor prostanoids and oxidative stress.

    Science.gov (United States)

    Carda, Ana P P; Marchi, Katia C; Rizzi, Elen; Mecawi, André S; Antunes-Rodrigues, José; Padovan, Claudia M; Tirapelli, Carlos R

    2015-01-01

    We hypothesized that acute stress would induce endothelial dysfunction. Male Wistar rats were restrained for 2 h within wire mesh. Functional and biochemical analyses were conducted 24 h after the 2-h period of restraint. Stressed rats showed decreased exploration on the open arms of an elevated-plus maze (EPM) and increased plasma corticosterone concentration. Acute restraint stress did not alter systolic blood pressure, whereas it increased the in vitro contractile response to phenylephrine and serotonin in endothelium-intact rat aortas. NG-nitro-l-arginine methyl ester (l-NAME; nitric oxide synthase, NOS, inhibitor) did not alter the contraction induced by phenylephrine in aortic rings from stressed rats. Tiron, indomethacin and SQ29548 reversed the increase in the contractile response to phenylephrine induced by restraint stress. Increased systemic and vascular oxidative stress was evident in stressed rats. Restraint stress decreased plasma and vascular nitrate/nitrite (NOx) concentration and increased aortic expression of inducible (i) NOS, but not endothelial (e) NOS. Reduced expression of cyclooxygenase (COX)-1, but not COX-2, was observed in aortas from stressed rats. Restraint stress increased thromboxane (TX)B(2) (stable TXA(2) metabolite) concentration but did not affect prostaglandin (PG)F2α concentration in the aorta. Restraint reduced superoxide dismutase (SOD) activity, whereas concentrations of hydrogen peroxide (H(2)O(2)) and reduced glutathione (GSH) were not affected. The major new finding of our study is that restraint stress increases vascular contraction by an endothelium-dependent mechanism that involves increased oxidative stress and the generation of COX-derived vasoconstrictor prostanoids. Such stress-induced endothelial dysfunction could predispose to the development of cardiovascular diseases.

  11. [Effect of cadmium stress on physiological characteristics of garlic seedlings and the alleviation effects of exogenous calcium].

    Science.gov (United States)

    Li, He; Lian, Hai-feng; Liu, Shi-qi; Yu, Xin-hui; Sun, Ya-li; Guo, Hui-ping

    2015-04-01

    In the experiment, the effects of exogenous cadmium (Cd2+) and calcium (Ca2+) in nutrient solution on growth, photosynthetic characteristics, enzymes activities, main mineral elements absorption of garlic seedlings were studied. The results showed that cadmium could obviously inhibit the growth of garlic seedlings, decrease the pigment contents and photosynthetic parameters (P(n), E, g(s)) of leaves, reduced the enzymes (SOD, POD, CAT) activities and increase the MDA content of leaves, and also could reduce the N, P, K, Ca, Mg contents and increase the Cd content of roots. The growth was promoted after adding exogenous calcium to garlic seedlings under cadmium stress, which reflected that the morphological indexes were increased at first and then decreased with the increase of exogenous calcium concentrations, and were maximized when the exogenous calcium was 2 or 3 mmol x L(-1). At the same time, the pigment contents and photosynthetic parameters (P(n), E, g(s)) of leaves showed a similar tendency with the morphological indexes, and they were the highest when the exogenous calcium was 2 or 3 mmol x L(-1). In addition, adding exogenous calcium to garlic seedlings under cadmium stress enhanced the enzymes (SOD, POD, CAT) activities and decreased the MDA content of leaves, also added the N, P, K, Ca, Mg contents and reduced the Cd content of roots, and the effect was best when the exogenous calcium concentration was 2 or 3 mmol x L(-1).

  12. Relaxin and atrial natriuretic peptide pathways participate in the anti-fibrotic effect of a melon concentrate in spontaneously hypertensive rats

    Directory of Open Access Journals (Sweden)

    Julie Carillon

    2016-04-01

    Full Text Available Background: In spontaneously hypertensive rats (SHR, a model of human essential hypertension, oxidative stress is involved in the development of cardiac hypertrophy and fibrosis associated with hypertension. Dietary supplementation with agents exhibiting antioxidant properties could have a beneficial effect in remodeling of the heart. We previously demonstrated a potent anti-hypertrophic effect of a specific melon (Cucumis melo L. concentrate with antioxidant properties in spontaneously hypertensive rats. Relaxin and atrial natriuretic peptide (ANP were reported to reduce collagen deposition and fibrosis progression in various experimental models. Objective: The aim of the present investigation was to test the hypothesis that, beside reduction in oxidative stress, the melon concentrate may act through relaxin, its receptor (relaxin/insulin-like family peptide receptor 1, RXFP1, and ANP in SHR. Design and results: The melon concentrate, given orally during 4 days, reduced cardiomyocyte size (by 25% and totally reversed cardiac collagen content (Sirius red staining in SHR but not in their normotensive controls. Treatment with the melon concentrate lowered cardiac nitrotyrosine-stained area (by 45% and increased by 17–19% the cardiac expression (Western blot of superoxide dismutase (SOD and glutathione peroxidase. In addition, plasma relaxin concentration was normalized while cardiac relaxin (Western blot was lowered in treated SHR. Cardiac relaxin receptor level determined by immunohistochemical analysis increased only in treated SHR. Similarly, the melon concentrate reversed the reduction of plasma ANP concentration and lowered its cardiac expression. Conclusions: The present results demonstrate that reversal of cardiac fibrosis by the melon concentrate involves antioxidant defenses, as well as relaxin and ANP pathways restoration. It is suggested that dietary SOD supplementation could be a useful additional strategy against cardiac hypertrophy

  13. Fatigue life estimation of welded components considering welding residual stress relaxation and its mean stress effect

    International Nuclear Information System (INIS)

    Han, Seung Ho; Han, Jeong Woo; Shin, Byung Chun; Kim, Jae Hoon

    2003-01-01

    The fatigue life of welded joints is sensitive to welding residual stress and complexity of their geometric shapes. To predict the fatigue life more reasonably, the effects of welding residual stress and its relaxation on their fatigue strengths should be considered quantitatively, which are often regarded to be equivalent to the effects of mean stresses by external loads. The hot-spot stress concept should be also adopted which can reduce the dependence of fatigue strengths for various welding details. Considering the factors mentioned above, a fatigue life prediction model using the modified Goodman's diagram was proposed. In this model, an equivalent stress was introduced which is composed of the mean stress based on the hot-spot stress concept and the relaxed welding residual stress. From the verification of the proposed model to real welding details, it is proved that this model can be applied to predict reasonably their fatigue lives

  14. Effect of salinity stress on growth, lipid productivity, fatty acid composition, and biodiesel properties in Acutodesmus obliquus and Chlorella vulgaris.

    Science.gov (United States)

    Pandit, Priti Raj; Fulekar, Madhusudan H; Karuna, Mallampalli Sri Lakshmi

    2017-05-01

    Two microalgae strains including Chlorella vulgaris and Acutodesmus obliquus were grown on BG11 medium with salinity stress ranging from 0.06 to 0.4 M NaCl. Highest lipid content in C. vulgaris and A. obliquus was 49 and 43% in BG11 amended with 0.4 M NaCl. The microalgal strains C. vulgaris and A. obliquus grow better at 0.06 M NaCl concentration than control condition. At 0.06 M NaCl, improved dry biomass content in C. vulgaris and A. obliquus was 0.92 and 0.68 gL -1 , respectively. Stress biomarkers like reactive oxygen species, antioxidant enzyme catalase, and ascorbate peroxidase were also lowest at 0.06 M NaCl concentration revealing that both the microalgal strains are well acclimatized at 0.06 M NaCl concentration. The fatty acid composition of the investigated microalgal strains was also improved by increased NaCl concentration. At 0.4 M NaCl, palmitic acid (37%), oleic acid (15.5%), and linoleic acid (20%) were the dominant fatty acids in C. vulgaris while palmitic acid (54%) and stearic acid (26.6%) were major fatty acids found in A. obliquus. Fatty acid profiling of C. vulgaris and A. obliquus significantly varied with salinity concentration. Therefore, the study showed that salt stress is an effective stress that could increase not only the lipid content but also improved the fatty acid composition which could make C. vulgaris and A. obliquus potential strains for biodiesel production.

  15. Effects of stress on health and aging: Two paradoxes

    OpenAIRE

    Aldwin, Carolyn M; Yancura, Loriena A.

    2010-01-01

    Although older adults are thought to experience more stress and to be more vulnerable to its adverse effects, they often report less stress than younger adults and sometimes show more resilience. Paradoxically, while stress sometimes has long-term positive effects on well-being, studies differ as to whether this increases or decreases with age. We conclude that older individuals have learned to appraise and cope differently with stress. This protects them in spite of their increased physiolog...

  16. Effect of stress on turbine fish passage mortality estimates

    International Nuclear Information System (INIS)

    Ruggles, C.P.

    1993-01-01

    Tests were conducted with juvenile alewife to determine the effects of four experimental protocols upon turbine fish passage mortality estimates. Three protocols determined the effect of cumulative stresses upon fish, while the fourth determined the effect of long range truck transportation prior to release into the penstock or tailrace. The wide range in results were attributed to the presence or absence of additional stress factors associated with the experiments. For instance, fish may survive passage through a turbine, or non-turbine related stresses imposed by the investigator; however, when both are imposed, the cumulative stresses may be lethal. The impact of protocol stress on turbine mortality estimates becomes almost exponential after control mortality exceeds 10%. Valid turbine related mortalities may be determined only after stresses associated with experimental protocol are adequately reduced. This is usually indicated by a control mortality of less than 10%. 14 refs., 5 figs., 6 tabs

  17. Effects of heavy metals on biomarkers for oxidative stress in Griffon vulture (Gyps fulvus)

    International Nuclear Information System (INIS)

    Espín, Silvia; Martínez-López, Emma; Jiménez, Pedro; María-Mojica, Pedro; García-Fernández, Antonio J.

    2014-01-01

    Metals are involved in the formation of reactive oxygen species (ROS) which may result in metal-related oxidative stress that can lead to oxidative damage to lipids, DNA and proteins. It is necessary to understand the mechanisms of metal toxicity in wild birds, and the concentrations that cause effects on oxidative stress biomarkers. The aim of this study is to assess the concentrations of lead (Pb), cadmium (Cd), mercury (Hg), copper (Cu) and zinc (Zn) with regards to oxidative stress in blood samples of 66 Griffon vultures (Gyps fulvus) from two areas of the Autonomous Community of Valencia (East of Spain). The two study areas (Alcoy n=36 and Cinctorres n=30) were selected as random locations of interest that had not yet been studied, and are feeding stations where supplementary food, mainly of pork origin, is provided for vultures. Given that the two study areas are not considered polluted sites, we expected to find low metal concentrations. However, there are no known threshold concentrations at which metals can affect antioxidant systems, and low metal levels may have an effect on antioxidant biomolecules. In this study, since sampling was done at the beginning of the hunting season, the low Pb levels found in most Griffon vultures from Alcoy and Cinctorres (median=12.37 and 16.26 μg/dl, respectively) are suggestive of background levels usually found in vultures that feed on pork carcasses all year round. The ingestion of game meat with bullet fragments in carcasses or with Pb shots embedded in the flesh could be the cause of the high blood Pb concentrations found in three vultures from Cinctorres (83, 290 and 362 μg/dl). Griffon vultures feeding in Cinctorres had enhanced CAT and GST activities and tGSH concentrations, which may be interpreted as protective response against the higher TBARS levels. This study provides threshold concentrations at which metals affect antioxidant system derived from 66 samples of Griffon vulture. Blood Cd concentrations

  18. Effects of heavy metals on biomarkers for oxidative stress in Griffon vulture (Gyps fulvus)

    Energy Technology Data Exchange (ETDEWEB)

    Espín, Silvia, E-mail: silvia.espin@um.es [Department of Toxicology, Faculty of Veterinary Medicine, University of Murcia, Campus de Espinardo, 30100 Murcia (Spain); Martínez-López, Emma, E-mail: emmaml@um.es [Department of Toxicology, Faculty of Veterinary Medicine, University of Murcia, Campus de Espinardo, 30100 Murcia (Spain); Jiménez, Pedro, E-mail: pjjm@um.es [Department of Toxicology, Faculty of Veterinary Medicine, University of Murcia, Campus de Espinardo, 30100 Murcia (Spain); María-Mojica, Pedro, E-mail: pmmojica@um.es [Department of Toxicology, Faculty of Veterinary Medicine, University of Murcia, Campus de Espinardo, 30100 Murcia (Spain); “Santa Faz” Wildlife Recovery Centre, Comunidad Valenciana, Alicante (Spain); García-Fernández, Antonio J., E-mail: ajgf@um.es [Department of Toxicology, Faculty of Veterinary Medicine, University of Murcia, Campus de Espinardo, 30100 Murcia (Spain)

    2014-02-01

    Metals are involved in the formation of reactive oxygen species (ROS) which may result in metal-related oxidative stress that can lead to oxidative damage to lipids, DNA and proteins. It is necessary to understand the mechanisms of metal toxicity in wild birds, and the concentrations that cause effects on oxidative stress biomarkers. The aim of this study is to assess the concentrations of lead (Pb), cadmium (Cd), mercury (Hg), copper (Cu) and zinc (Zn) with regards to oxidative stress in blood samples of 66 Griffon vultures (Gyps fulvus) from two areas of the Autonomous Community of Valencia (East of Spain). The two study areas (Alcoy n=36 and Cinctorres n=30) were selected as random locations of interest that had not yet been studied, and are feeding stations where supplementary food, mainly of pork origin, is provided for vultures. Given that the two study areas are not considered polluted sites, we expected to find low metal concentrations. However, there are no known threshold concentrations at which metals can affect antioxidant systems, and low metal levels may have an effect on antioxidant biomolecules. In this study, since sampling was done at the beginning of the hunting season, the low Pb levels found in most Griffon vultures from Alcoy and Cinctorres (median=12.37 and 16.26 μg/dl, respectively) are suggestive of background levels usually found in vultures that feed on pork carcasses all year round. The ingestion of game meat with bullet fragments in carcasses or with Pb shots embedded in the flesh could be the cause of the high blood Pb concentrations found in three vultures from Cinctorres (83, 290 and 362 μg/dl). Griffon vultures feeding in Cinctorres had enhanced CAT and GST activities and tGSH concentrations, which may be interpreted as protective response against the higher TBARS levels. This study provides threshold concentrations at which metals affect antioxidant system derived from 66 samples of Griffon vulture. Blood Cd concentrations

  19. Effects of Stress Inoculation Training on Anxiety, Stress, and Academic Performance among Adolescents.

    Science.gov (United States)

    Kiselica, Mark S.; And Others

    1994-01-01

    Examined effectiveness of preventive stress inoculation program for adolescents (n=48) that consisted of progressive muscle relaxation, cognitive restructuring, and assertiveness training. Compared with control subjects, trainees showed significantly greater improvements on self-report measures of trait anxiety and stress-related symptoms at…

  20. Effect of interfacial stresses in an elastic body with a nanoinclusion

    Science.gov (United States)

    Vakaeva, Aleksandra B.; Grekov, Mikhail A.

    2018-05-01

    The 2-D problem of an infinite elastic solid with a nanoinclusion of a different from circular shape is solved. The interfacial stresses are acting at the interface. Contact of the inclusion with the matrix satisfies the ideal conditions of cohesion. The generalized Laplace - Young law defines conditions at the interface. To solve the problem, Gurtin - Murdoch surface elasticity model, Goursat - Kolosov complex potentials and the boundary perturbation method are used. The problem is reduced to the solution of two independent Riemann - Hilbert's boundary problems. For the circular inclusion, hypersingular integral equation in an unknown interfacial stress is derived. The algorithm of solving this equation is constructed. The influence of the interfacial stress and the dimension of the circular inclusion on the stress distribution and stress concentration at the interface are analyzed.

  1. Resistance to early-life stress in mice: effects of genetic background and stress duration

    Directory of Open Access Journals (Sweden)

    Helene M. Savignac

    2011-04-01

    Full Text Available Early-life stress can induce marked behavioural and physiological impairments in adulthood including cognitive deficits, depression, anxiety and gastrointestinal dysfunction. Although robust rat models of early-life stress exist there are few established effective paradigms in the mouse. Genetic background and protocol parameters used are two critical variables in such model development.Thus we investigated the impact of two different early-life stress protocols in two commonly used inbred mouse strains. C57BL/6 and innately anxious BALB/c male mice were maternally deprived 3 hrs daily, either from postnatal day 1 to 14 (Protocol 1 or 6 to 10 (Protocol 2. Animals were assessed in adulthood for cognitive performance (spontaneous alternation behaviour test, anxiety (open field, light/dark box and elevated plus maze tests and depression-related behaviours (forced swim test in addition to stress-sensitive physiological changes. Overall, the results showed that early-life stressed mice from both strains displayed good cognitive ability and no elevations in anxiety. However, paradoxical changes occurred in C57BL/6 mice as the longer protocol (protocol 1 decreased anxiety in the light-dark box and increased exploration in the elevated plus maze. In BALB/c mice there were also limited effects of maternal separation with both separation protocols inducing reductions in stress-induced defecation and protocol 1 reducing the colon length. These data suggest that, independent of stress duration, mice from both strains were on the whole resilient to the maladaptive effects of early-life stress. Thus maternal-separation models of brain-gut axis dysfunction should rely on either different stressor protocols or other strains of mice.

  2. No effect of stress on false recognition.

    Science.gov (United States)

    Beato, María Soledad; Cadavid, Sara; Pulido, Ramón F; Pinho, María Salomé

    2013-02-01

    The present study aimed to analyze the effect of acute stress on false recognition in the Deese/Roediger-McDermott (DRM) paradigm. In this paradigm, lists of words associated with a non-presented critical lure are studied and, in a subsequent memory test, critical lures are often falsely remembered. In two experiments, participants were randomly assigned to either the stress group (Trier Social Stress Test) or the no-stress control group. Because we sought to control the level-of-processing at encoding, in Experiment 1, participants created a visual mental image for each presented word (deep encoding). In Experiment 2, participants performed a shallow encoding (to respond whether each word contained the letter "o"). The results indicated that, in both experiments, as predicted, heart rate and STAI-S scores increased only in the stress group. However, false recognition did not differ across stress and no-stress groups. Results suggest that, although psychosocial stress was successfully induced, it does not enhance the vulnerability of individuals with acute stress to DRM false recognition, regardless of the level of processing.

  3. Antioxidant effect of mogrosides against oxidative stress induced by palmitic acid in mouse insulinoma NIT-1 cells

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Q.; Chen, S.Y.; Deng, L.D.; Feng, L.P.; Huang, L.Z.; Yu, R.R. [Department of Pharmacy, Guilin Medical University, Guilin (China)

    2013-11-18

    Excessive oxidative stress in pancreatic β cells, caused by glucose and fatty acids, is associated with the pathogenesis of type 2 diabetes. Mogrosides have shown antioxidant and antidiabetic activities in animal models of diabetes, but the underlying mechanisms remain unclear. This study evaluated the antioxidant effect of mogrosides on insulinoma cells under oxidative stress caused by palmitic acid, and investigated the underlying molecular mechanisms. Mouse insulinoma NIT-1 cells were cultured in medium containing 0.75 mM palmitic acid, mimicking oxidative stress. The effects of 1 mM mogrosides were determined with the dichlorodihydrofluorescein diacetate assay for intracellular reactive oxygen species (ROS) and FITC-Annexin V/PI assay for cell apoptosis. Expression of glucose transporter-2 (GLUT2) and pyruvate kinase was determined by semi-quantitative reverse-transcription polymerase chain reaction. Palmitic acid significantly increased intracellular ROS concentration 2-fold (P<0.05), and decreased expression of GLUT2 (by 60%, P<0.05) and pyruvate kinase (by 80%, P<0.05) mRNAs in NIT-1 cells. Compared with palmitic acid, co-treatment with 1 mM mogrosides for 48 h significantly reduced intracellular ROS concentration and restored mRNA expression levels of GLUT2 and pyruvate kinase. However, mogrosides did not reverse palmitic acid-induced apoptosis in NIT-1 cells. Our results indicate that mogrosides might exert their antioxidant effect by reducing intracellular ROS and regulating expression of genes involved in glucose metabolism. Further research is needed to achieve a better understanding of the signaling pathway involved in the antioxidant effect of mogrosides.

  4. Interactive effects of chronic stress and a high-sucrose diet on nonalcoholic fatty liver in young adult male rats.

    Science.gov (United States)

    Corona-Pérez, Adriana; Díaz-Muñoz, Mauricio; Cuevas-Romero, Estela; Luna-Moreno, Dalia; Valente-Godínez, Héctor; Vázquez-Martínez, Olivia; Martínez-Gómez, Margarita; Rodríguez-Antolín, Jorge; Nicolás-Toledo, Leticia

    2017-11-01

    Glucocorticoids have been implicated in nonalcoholic fatty liver diseases (NAFLD). The influence of a palatable diet on the response to stress is controversial. This study explored whether a high-sucrose diet could protect from hepatic steatosis induced by chronic restraint stress in young adult rats. Male Wistar rats aged 21 days were allocated into four groups (n = 6-8 per group): control, chronic restraint stress, 30% sucrose diet, and 30% sucrose diet plus chronic restraint stress. After being exposed to either tap water or sucrose solution during eight weeks, half of the rats belonging to each group were subject or not to repeated restraint stress (1 h per day, 5 days per week) during four weeks. Triacylglycerol (TAG), oxidative stress, activity of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD-1), infiltration of immune cells, and glycogen amount in the liver were quantified. Serum concentrations of corticosterone and testosterone were also measured. The stressed group showed normal serum concentrations of corticosterone and did not have hepatic steatosis. However, this group showed increased glycogen, inflammation, mild fibrosis, oxidative stress, and a high activity of 11β-HSD-1 in the liver. The group exposed to the high-sucrose diet had lower concentrations of corticosterone, hepatic steatosis and moderate fibrosis. The group subject to high-sucrose diet plus chronic restraint stress showed low concentrations of corticosterone, hepatic steatosis, oxidative stress, and high concentrations of testosterone. Thus, restraint stress and a high-sucrose diet each generate different components of nonalcoholic fatty liver in young adult rats. The combination of both the factors could promote a faster development of NAFLD.

  5. Metabolic and behavioral effects of ractopamine at continuous low levels in rats under stress

    Directory of Open Access Journals (Sweden)

    Edna Lopes

    2015-06-01

    Full Text Available This study aimed at evaluating the effect of ractopamine (RAC on metabolism, zootechnical performance, body composition, and behavior in Wistar rats submitted to acute and chronic restrain stress. The oral dose of 5 mg/kg of RAC was administered in periods of 0, 7, 14, 21, and 28 days. The elevated plus-maze test (EPMT was used for behavioral assessment. Blood, carcass and viscera characteristics were evaluated. Insulin-dependent glucose transporters (GLUT-4 were semi-quantified by Western Blot in epididymal adipocytes. RAC periods associated with chronic stress increased the GLUT-4 protein expression in adipose tissue in a time-dependent manner (P=0.01, i.e., the longer the RAC addition period, the higher the GLUT-4 concentration in chronically stressed animals (0=1.42; 7=1.19; 14=2.03; 21=1.59; 28=2.35. The stress periods combined with RAC increased the time spent in the opened arms of the maze (Chronic stress: 0=10.6; 7=8.7; 14=5.9; 21=12.3; 28=4.0; Acute stress 0=3.1; 7= 4.7; 14=7.5; 21=0.0; 28=2.8 (P=0.04. Chronic (entries on the closed arms [ECA]=3.60 and acute (ECA=3.80 stress reduced locomotive activity in the maze (P=0.03. The results suggested that stress could negatively affect the possible benefits offered by the RAC, mainly impairing the adipose tissue metabolism and behavior in the animals.

  6. The Effects of Season of Birth on the Inflammatory Response to Psychological Stress in Hainan Island, China.

    Directory of Open Access Journals (Sweden)

    Aki Yazawa

    Full Text Available Season of birth (SOB has been investigated as one of the environmental factors that might epigenetically determine the physiology of individuals. This study investigated the role of SOB in the association between Quality of Life (QOL, a proxy of psychological stress status, and C-reactive protein (CRP concentration (i.e., inflammatory status among 1,085 adults (aged 20-57 years old in Hainan Island, China. High sensitivity CRP concentration was measured in dried blood spot samples, while the abbreviated version of the World Health Organization's QOL questionnaire was used to gather information on six QOL domains. Analysis stratified by three historically distinct age groups revealed a significant association between CRP concentration, SOB, QOL and an interaction between SOB and QOL among the youngest and oldest groups. In the oldest group, those born in the dry season had a higher CRP concentration with worse QOL whereas in the youngest group, there was a higher CRP concentration with better QOL. Annual per capita rice production, a proxy of population nutritional status in the year of birth, was found to predict CRP concentration only among the second oldest group. These findings suggest that the early environment might affect the immune response to psychological stress in adulthood and that its effect may differ by the time period in which people were born.

  7. The Effects of Season of Birth on the Inflammatory Response to Psychological Stress in Hainan Island, China.

    Science.gov (United States)

    Yazawa, Aki; Inoue, Yosuke; Stickley, Andrew; Li, Dandan; Du, Jianwei; Watanabe, Chiho

    2015-01-01

    Season of birth (SOB) has been investigated as one of the environmental factors that might epigenetically determine the physiology of individuals. This study investigated the role of SOB in the association between Quality of Life (QOL), a proxy of psychological stress status, and C-reactive protein (CRP) concentration (i.e., inflammatory status) among 1,085 adults (aged 20-57 years old) in Hainan Island, China. High sensitivity CRP concentration was measured in dried blood spot samples, while the abbreviated version of the World Health Organization's QOL questionnaire was used to gather information on six QOL domains. Analysis stratified by three historically distinct age groups revealed a significant association between CRP concentration, SOB, QOL and an interaction between SOB and QOL among the youngest and oldest groups. In the oldest group, those born in the dry season had a higher CRP concentration with worse QOL whereas in the youngest group, there was a higher CRP concentration with better QOL. Annual per capita rice production, a proxy of population nutritional status in the year of birth, was found to predict CRP concentration only among the second oldest group. These findings suggest that the early environment might affect the immune response to psychological stress in adulthood and that its effect may differ by the time period in which people were born.

  8. Effect of Seed Priming on Growth and Some Physiological Characteristics of Sesame (Sesamum indicum L. under salinity Stress Condition caused by Alkali Salts

    Directory of Open Access Journals (Sweden)

    H. Bekhrad

    2016-02-01

    the pot were created by adding NaHCO3, to half strength Hoagland’s solution. Control plants were only irrigated with half strength Hoagland’s solution. Plants were harvested after 45 days of seed sowing. After forty five days, shoot and root height, shoot and root dry weight, relative water content, Fv/Fm, chla, chlb, total chlorophyll, cartonoied content, potassium, sodium content and sodium to potassium, calcium and magnesium content were measured. Results and Discussion Results showed that salinity stress decreased shoot and root height and also shoot dry weight. Valdez-Aguilar and Reed (33 reported a decrease in Phasaeolus vulgaris L. growth with increasing sodium bicarbonate salt. By increasing sodium bicarbonate, salt relative water content decreased. Also, the decreases in relative water content have been reported in wheat under salinity stress caused by alkali condition (15. Salinity stress decreased leaf chlorophyll content and Fv/Fm. Similarly, Guo et al., (16 observed a decrease in leaf chlorophyll content and Fv/Fm with increasing sodium bicarbonate salt. Different treatments of priming increased root height and shoot dry weight compared with unprimed treatment with increasing salinity stress. Iqbal and Ashraf (18 indicated that priming increased growth in wheat under salinity stress caused by alkali condition. Moreover, relative water content, chlb content and Fv/Fm increased under different treatments of priming and stress. It seem that under stress condition, plants with maintain relative water content, chlb content and Fv/Fm, decreased the harmful effect stress. The highest shoot dry weight, relative water content, chlb content and Fv/Fm was observed at hydropriming treatment. Although salinity stress decreased K+ concentration and K+/Na+, but the Na+, Ca2+ and Mg2+ concentration increased. Zhang and Chun-Sheng (39 concluded that by increasing sodium bicarbonate salt, potassium content decreased in Lathyrus quinquenervius, whereas sodium and sodium

  9. The Effect of Pigment Volume Concentration on Film Formation and the Mechanical Properties of Coatings Based on Water-Dispersion Paint and Varnish Materials

    Science.gov (United States)

    Kasyanenko, I. M.; Kramarenko, V. Yu.

    2018-01-01

    The effect of pigment volume concentration (PVC) on the film formation process and properties of coatings based on the water dispersion of an Acronal 290D styrene-acrylate copolymer and a pigment/filler system used for paint materials in construction was investigated. An analysis of the results obtained is performed within the framework of the concept of the critical PVC. It is shown that the initiation and development of internal stresses occurs the faster, the higher the PVC, but the position of the maximum or the inflection point of the internal stress-drying time curve complies with a universal value of the solid volume content in the compositions. It is found that the internal stresses and Young's modulus of coatings are characterized by an extreme concentration relation that, for the reduced elastic modulus, can be described by a system of equations based on the Halpin-Tsai equation.

  10. Response of plants to high concentrations of uranium stress and the screening of remediation plants

    International Nuclear Information System (INIS)

    Tang Yongjin; Luo Xuegang; Zeng Feng; Jiang Shijie

    2013-01-01

    Studies of the resistance and accumulation ability of different plant species to uranium (U) has important influence on the bioremediation of U contaminated soil. The resistance and enrichment ability of high concentrations of U (500 mg · kg"-"1 soil) in fourteen plant species were investigated and evaluated in this study in order to screen remediation plants for governance soil U contamination. The results showed that: (1) high concentrations of U stress had different effects on the emergence and survival of the different plants. The seed emergence of Hibiscus esculentus was reduced by 2/3, but the seed emergence of Gynura cusimbua (D. Don) S. Moore, Chenopodium album L. and Phaseolus vulgaris var. humilis Alef were not reduced. Under the contaminated soil, all the sesamum indicum died within a month after the emergence and the survival number of Amaranth and Iresine herbstii 'Aureo-reticulata' reduced by about 80%. But the survival number of Alternanthera philoxeroides (Mart.) Griseb., Chenopodium album L. and Phaseolus vulgaris var. humilis Alef were not influenced. (2) The biomass of the plants would be reduced by 8-99% in the uranium-contaminated soil. The anti-stress ability of Phaseolus vulgaris var. humilis Alef was the strongest in the fourteen plants, and Cucurbita pepo L., Sorghumbicolor (L.) Moench, Ipomoea aquatica Forsk, Helianthus annuus, Chenopodium album L. and Alternanthera philoxeroides (Mart.) Griseb. showed some the anti-stress ability. (3) Significant differences were found in the capacity of plants to absorb uranium between under high-uranium contaminated soil and under the non-uranium contaminated soil were. The plants with higher uranium content in thenon-contaminated soil were Gomphrena globosa, and Cucurbita pepo L., which were 2.249 mg · kg"-"1 DW and 1.620 mg · kg"-"1 DW, respectively. But the plants with higher uranium content in the high uranium contaminated soil were Cichorium intybus L., Amaranth and Ipomoea aquatica Forsk, which

  11. Zeolites relieves inhibitory stress from high concentrations of long chain fatty acids.

    Science.gov (United States)

    Nordell, Erik; Hansson, Anna B; Karlsson, Martin

    2013-12-01

    Protein and fat rich slaughterhouse waste is a very attractive waste stream for the production of biogas because of the high biochemical methane potential of the substrate. The material has however some drawbacks as the sole material for biogas production due to the production of several process disturbing metabolites such as ammonia, sulfides and long chain fatty acids. We can in this work present results that show that zeolites have the potential to relieve inhibitory stress from the presence of long chain fatty acids. Moreover, the results strongly indicate that it is mainly acetic acid consumers that are most negatively affected by long chain fatty acids and that the mechanism of stress relief is an adsorption of long chain fatty acids to the zeolites. In addition to this, it is shown that the effect is immediate and that only a small amount of zeolites is necessary to cancel the inhibitory effect of long chain fatty acids. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Hormetic effects of noncoplanar PCB exposed to human lung fibroblast cells (HELF) and possible role of oxidative stress.

    Science.gov (United States)

    Hashmi, Muhammad Zaffar; Khan, Kiran Yasmin; Hu, Jinxing; Naveedullah; Su, Xiaomei; Abbas, Ghulam; Yu, Chunna; Shen, Chaofeng

    2015-12-01

    Hormesis, a biphasic dose-response phenomenon, which is characterized by stimulation of an end point at a low-dose and inhibition at a high-dose. In the present study we used human lungs fibroblast (HELF) cells as a test model to evaluate the role of oxidative stress (OS) in hormetic effects of non coplanar PCB 101. Results from 3-(4,5-dime-thylthiazol-2-yl)-2,5-diphenyltetrazo-lium bromide (MTT) assay indicated that PCB101 at lower concentrations (10(-5) to 10(-1) μg mL(-1) ) stimulated HELF cell proliferation and inhibited at high concentrations (1, 5, 10, and 20 μg mL(-1) ) in a dose- and time-dependent manner. Reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD) (except 48 h) showed a significant increase at higher concentrations of PCB 101 than those at the lower concentrations with the passage of time. Antioxidant enzymes such as glutathione peroxidase (GSH-Px) exhibited decreasing trends in dose and time dependent manner. Lipid peroxidation assay resulted in a significant increase (P PCB 101-treated HELF cells compared with controls, suggesting that OS plays a key role in PCB 101-induced toxicity. Comet assay indicated a significant increase in genotoxicity at higher concentrations of PCB 101 exposure compared to lower concentrations. Overall, we found that HELF cell proliferation was higher at low ROS level and vice versa, which revealed activation of cell signaling-mediated hormetic mechanisms. The results suggested that PCB 101 has hormetic effects to HELF cells and these were associated with oxidative stress. © 2014 Wiley Periodicals, Inc.

  13. Effects of high salinity from desalination brine on growth, photosynthesis, water relations and osmolyte concentrations of seagrass Posidonia australis.

    Science.gov (United States)

    Cambridge, M L; Zavala-Perez, A; Cawthray, G R; Mondon, J; Kendrick, G A

    2017-02-15

    Highly saline brines from desalination plants expose seagrass communities to salt stress. We examined effects of raised salinity (46 and 54psu) compared with seawater controls (37psu) over 6weeks on the seagrass, Posidonia australis, growing in tanks with the aim of separating effects of salinity from other potentially deleterious components of brine and determining appropriate bioindicators. Plants survived exposures of 2-4weeks at 54psu, the maximum salinity of brine released from a nearby desalination plant. Salinity significantly reduced maximum quantum yield of PSII (chlorophyll a fluorescence emissions). Leaf water potential (Ψ w ) and osmotic potential (Ψ π ) were more negative at increased salinity, while turgor pressure (Ψ p ) was unaffected. Leaf concentrations of K + and Ca 2+ decreased, whereas concentrations of sugars (mainly sucrose) and amino acids increased. We recommend leaf osmolarity, ion, sugar and amino acid concentrations as bioindicators for salinity effects, associated with brine released in desalination plant outfalls. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Regulation of water, salinity, and cold stress responses by salicylic acid

    Directory of Open Access Journals (Sweden)

    Kenji eMiura

    2014-01-01

    Full Text Available Salicylic acid (SA is a naturally occurring phenolic compound. SA plays an important role in the regulation of plant growth, development, ripening, and defense responses. The role of SA in the plant-pathogen relationship has been extensively investigated. In addition to defense responses, SA plays an important role in the response to abiotic stresses, including drought, low temperature, and salinity stresses. It has been suggested that SA has great agronomic potential to improve the stress tolerance of agriculturally important crops. However, the utility of SA is dependent on the concentration of the applied SA, the mode of application, and the state of the plants (e.g., developmental stage and acclimation. Generally, low concentrations of applied SA alleviate the sensitivity to abiotic stresses, and high concentrations of applied induce high levels of oxidative stress, leading to a decreased tolerance to abiotic stresses. In this chapter, the effects of SA on the water stress responses and regulation of stomatal closure are reviewed.

  15. Effect of external stress on deuteride (hydride) precipitation in Zircaloy-4 using in situ neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jun-li [Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); An, Ke; Stoica, Alexandru D. [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Heuser, Brent J., E-mail: bheuser@illinois.edu [Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)

    2017-04-15

    In situ neutron diffraction is utilized to study the deuteride (hydride) precipitation behavior in a cold-worked stress-relieved (CWSR) Zircaloy-4 material upon cooling from 420 °C to room temperature with a 78 MPa external stress applied along the rolling direction (RD) of the material. Two banks detector capture the diffraction signal from two principal directions of the specimen, the normal direction (ND) and the rolling direction (RD). The evolution of deuterium concentration in zirconium solid solution along the two specimen directions is measured by studying the δ-(220) peak intensity, applying the Rietveld refinement method to the diffraction data and using the measured zirconium c-axis lattice distortion. The deuterium concentration is observed to be higher for zirconium grains in the ND than the RD. The terminal solid solubility of precipitation (TSSp) for deuterium in the solution is then described using the Arrhenius equation. It is observed that the applied stress reduces the energy term Q in the Arrhenius equation when compared with the unstressed Q values from the work of others. A model by Puls is applied to study the effect of stress on deuterium solubility, with polycrystalline hydride precipitation strain calculated using the Kearns factor representative of the studied material. The experimental result does not agree with the model prediction of Puls.

  16. Long-Term Effectiveness of Stress Management at Work: Effects of the Changes in Perceived Stress Reactivity on Mental Health and Sleep Problems Seven Years Later.

    Science.gov (United States)

    Herr, Raphael M; Barrech, Amira; Riedel, Natalie; Gündel, Harald; Angerer, Peter; Li, Jian

    2018-02-03

    The reduction of stress reactivity resulting from stress management interventions prevents disorders and improves mental health, however, its long-term sustainability has been little examined. The objective of this study was, therefore, to determine the effectiveness of a stress management intervention, designed to improve stress reactivity, for mental health and sleep problems seven years later, using longitudinal data from 101 male industrial workers. Linear regressions estimated the adjusted effects of the changes in stress reactivity in general as well as in its six subdimensions (work overload, social conflict, social stress, failure at work, and anticipatory and prolonged reactivity) on depression, anxiety, and sleep problems seven years later. The improvement of the prolonged reactivity had positive effects on depression, anxiety, and sleep problems (unstandardized regression coefficients [ Bs ] ≥ 0.35, all p -values ≤ 0.01). Depression and sleep problems were further improved by a reduction of the reactivity to social conflicts ( Bs ≥ 0.29, p -values stress reactivity resulting from a work stress intervention was effective and generally long-lasting in preventing mental health and sleep problems. The reduction of the prolonged reactivity seems of particular importance and efficient in inhibiting negative stress manifestations.

  17. Physiological Response of Lactobacillus plantarum to Salt and Nonelectrolyte Stress

    Science.gov (United States)

    Glaasker, Erwin; Tjan, Frans S. B.; Ter Steeg, Pieter F.; Konings, Wil N.; Poolman, Bert

    1998-01-01

    In this report, we compared the effects on the growth of Lactobacillus plantarum of raising the medium molarity by high concentrations of KCl or NaCl and iso-osmotic concentrations of nonionic compounds. Analysis of cellular extracts for organic constituents by nuclear magnetic resonance spectroscopy showed that salt-stressed cells do not contain detectable amounts of organic osmolytes, whereas sugar-stressed cells contain sugar (and some sugar-derived) compounds. The cytoplasmic concentrations of lactose and sucrose in growing cells are always similar to the concentrations in the medium. By using the activity of the glycine betaine transport system as a measure of hyperosmotic conditions, we show that, in contrast to KCl and NaCl, high concentrations of sugars (lactose or sucrose) impose only a transient osmotic stress because external and internal sugars equilibrate after some time. Analysis of lactose (and sucrose) uptake also indicates that the corresponding transport systems are neither significantly induced nor activated directly by hyperosmotic conditions. The systems operate by facilitated diffusion and have very high apparent affinity constants for transport (>50 mM for lactose), which explains why low sugar concentrations do not protect against hyperosmotic conditions. We conclude that the more severe growth inhibition by salt stress than by equiosmolal concentrations of sugars reflects the inability of the cells to accumulate K+ (or Na+) to levels high enough to restore turgor as well as deleterious effects of the electrolytes intracellularly. PMID:9721316

  18. Numerical Investigation on Stress Concentration of Tension Steel Bars with One or Two Corrosion Pits

    Directory of Open Access Journals (Sweden)

    Jian Hou

    2015-01-01

    Full Text Available Pitting corrosion has been observed in steel bars of existing reinforced concrete (RC structures in different erosion environments and has been identified as a potential origin for fatigue crack nucleation. In the present study, under uniaxial tension loading, stress distribution in the steel bars with one or two semiellipsoidal corrosion pits has systematically been investigated by conducting a series of three-dimensional semiellipsoidal pitted models. Based on the finite element analyses, it is shown that stress concentration factor (SCF increases linearly with increasing pit aspect ratio (a/b and increases nonlinearly with increasing pit relative depth (a/R for single corrosion pit problem. For double corrosion pits problem, the SCF decreases nonlinearly with increasing angle of two transverse pits (θ. The interaction of two longitudinal pits can be ignored in the calculation of SCF even if the distance of two pits (d is very small.

  19. Surplus dietary tryptophan reduces plasma cortisol and noradrenaline concentrations and enhances recovery after social stress in pigs

    NARCIS (Netherlands)

    Koopmans, S.J.; Ruis, M.A.W.; Dekker, R.A.; Diepen, van J.T.M.; Korte, S.M.; Mroz, Z.

    2005-01-01

    Social stress occurs in intensive pig farming due to aggressive behavior. This stress may be reduced at elevated dietary levels of tryptophan (TRP). In this study, we compared the effects of high (13.2%) vs. normal (3.4%) dietary TRP to large neutral amino acid (LNAA) ratios on behavior and stress

  20. Water stress mitigates the negative effects of ozone on photosynthesis and biomass in poplar plants.

    Science.gov (United States)

    Gao, Feng; Catalayud, Vicent; Paoletti, Elena; Hoshika, Yasutomo; Feng, Zhaozhong

    2017-11-01

    Tropospheric ozone (O 3 ) pollution frequently overlaps with drought episodes but the combined effects are not yet understood. We investigated the physiological and biomass responses of an O 3 sensitive hybrid poplar clone ('546') under three O 3 levels (charcoal-filtered ambient air, non-filtered ambient air (NF), and NF plus 40 ppb) and two watering regimes (well-watered (WW) and reduced watering (RW), i.e. 40% irrigation) for one growing season. Water stress increased chlorophyll and carotenoid contents, protecting leaves from pigment degradation by O 3 . Impairment of photosynthesis by O 3 was also reduced by stomatal closure due to water stress, which preserved light-saturated CO 2 assimilation rate, and the maximum carboxylation efficiency. Water stress increased water use efficiency of the leaves while O 3 decreased it, showing significant interactions. Effects were more evident in older leaves than in younger leaves. Water stress reduced biomass production, but the negative effects of O 3 were less in RW than in WW for total biomass per plant. A stomatal O 3 flux-based dose-response relationship was parameterized considering water stress effects, which explained biomass losses much better than a concentration-based approach. The O 3 critical level of Phytotoxic Ozone Dose over a threshold of 7 nmol O 3 .m -2 .s -1 (POD 7 ) for a 4% biomass loss in this poplar clone under different water regimes was 4.1 mmol m -2 . Our results suggest that current O 3 levels in most parts of China threaten poplar growth and that interaction with water availability is a key factor for O 3 risk assessment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Environmental stresses can alleviate the average deleterious effect of mutations

    Directory of Open Access Journals (Sweden)

    Leibler Stanislas

    2003-05-01

    Full Text Available Abstract Background Fundamental questions in evolutionary genetics, including the possible advantage of sexual reproduction, depend critically on the effects of deleterious mutations on fitness. Limited existing experimental evidence suggests that, on average, such effects tend to be aggravated under environmental stresses, consistent with the perception that stress diminishes the organism's ability to tolerate deleterious mutations. Here, we ask whether there are also stresses with the opposite influence, under which the organism becomes more tolerant to mutations. Results We developed a technique, based on bioluminescence, which allows accurate automated measurements of bacterial growth rates at very low cell densities. Using this system, we measured growth rates of Escherichia coli mutants under a diverse set of environmental stresses. In contrast to the perception that stress always reduces the organism's ability to tolerate mutations, our measurements identified stresses that do the opposite – that is, despite decreasing wild-type growth, they alleviate, on average, the effect of deleterious mutations. Conclusions Our results show a qualitative difference between various environmental stresses ranging from alleviation to aggravation of the average effect of mutations. We further show how the existence of stresses that are biased towards alleviation of the effects of mutations may imply the existence of average epistatic interactions between mutations. The results thus offer a connection between the two main factors controlling the effects of deleterious mutations: environmental conditions and epistatic interactions.

  2. Effects of stress on swelling in reactor fuel cladding

    International Nuclear Information System (INIS)

    Bates, J.F.; Gilbert, E.R.

    1977-01-01

    The purpose of this report is to describe the effect of stress on swelling in both annealed and 20% cold worked 316 stainless steel. An effect of stress on swelling in irradiated metals has been postulated for some time. Low fluence data confirmed that indeed a tensile stress can increase swelling in irradiated annealed 316 stainless steel and that the maximum swelling occurs at an intermediate stress level which is approximately equal to the proportional elastic limit of the material. The specimens discussed above were examined by transmission electron microscopy and an effect of stress on the microstructure of the annealed and 20% cold worked 316 specimens has been observed. Howver, as yet, copious swelling had not occurred in the 20% cold worked material. Specimens of 20% cold worked 316 fabricated from the same heat of material as those described above have now been irradiated to sufficiently high neutron fluences that swelling has occurred in both the annealed and cold worked conditions. Swelling increases linearly with stress for both materials. However, for solution annealed 316, swelling reaches a maximum at approximately 136 MPa, whereupon further increases in stress result in reduced swelling. It is felt that this reduction in swelling is related to the onset of plastic yielding in the material. The swelling observed in the 20% CW 316 and the solution annealed 316 below the maximum swelling stress can be adequately described by an equation of the form: S = S 0 (1 + Psigma). No strong effect of stress on changing the incubation period associated with void nucleation was found. (Auth.)

  3. Friction stress effects on mode I crack growth predictions

    NARCIS (Netherlands)

    Chen, Q.; Deshpande, V.S.; Giessen, E. van der; Needleman, A.

    2003-01-01

    The effect of a lattice friction stress on the monotonic growth of a plane strain mode I crack under small-scale yielding conditions is analyzed using discrete dislocation plasticity. When the friction stress is increased from zero to half the dislocation nucleation stress, the crack tip stress

  4. The effects of strain rate and carbon concentration on the dynamic strain aging of cold rolled Ni-based alloy in high temperature water

    International Nuclear Information System (INIS)

    Kuang, Wenjun; Was, Gary S.

    2015-01-01

    Graphical abstract: The stress amplitude of serrations first increases with decreasing strain rate and then gradually saturates. The matrix carbon concentration affects the stress amplitude and the tendency to saturation. - Abstract: The effect of strain rate on dynamic strain aging of cold-rolled Ni-based alloy was investigated. With decreasing strain rate, the stress amplitude of serrations first increased and then saturated. Compared with the solution-annealed condition, the thermally-treated condition produced smaller stress amplitudes that saturated at a lower strain rate. Observations are consistent with a mechanism in which the locking strength of solute atmospheres first increases with increasing solute atom arrival at dislocations and gradually saturates as solute reaches a critical level

  5. Effects of concentrated sunlight on organic photovoltaics

    DEFF Research Database (Denmark)

    Tromholt, Thomas; Katz, Eugene A.; Hirsch, Baruch

    2010-01-01

    We report the effects of concentrated sunlight on key photovoltaic parameters and stability of organic photovoltaics (OPV). Sunlight collected and concentrated outdoors was focused into an optical fiber and delivered onto a 1 cm2 bulk-heterojunction cell. Sunlight concentration C was varied gradu...

  6. The influence of discontinuity and orthotropy of fracture toughness on conditions of fracture initiation in singular stress concentrators

    Czech Academy of Sciences Publication Activity Database

    Klusák, Jan; Profant, T.; Knésl, Zdeněk; Kotoul, M.

    2013-01-01

    Roč. 110, SEP (2013), s. 438-447 ISSN 0013-7944 R&D Projects: GA ČR GAP108/10/2049 Institutional support: RVO:68081723 Keywords : Stability criterion of notch es * crack initiation * Singular stress concentrators * bi-material notch Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.662, year: 2013

  7. Correlates of cortisol in human hair: implications for epidemiologic studies on health effects of chronic stress.

    Science.gov (United States)

    Wosu, Adaeze C; Valdimarsdóttir, Unnur; Shields, Alexandra E; Williams, David R; Williams, Michelle A

    2013-12-01

    Assessment of cortisol concentrations in hair is one of the latest innovations for measuring long-term cortisol exposure. We performed a systematic review of correlates of cortisol in human hair to inform the design, analysis, and interpretation of future epidemiologic studies. Relevant publications were identified through electronic searches on PubMed, WorldCat, and Web of Science using keywords, "cortisol," "hair," "confounders," "chronic," "stress," and "correlates." Thirty-nine studies were included in this review. Notwithstanding scarce data and some inconsistencies, investigators have found hair cortisol concentrations to be associated with stress-related psychiatric symptoms and disorders (e.g., post-traumatic stress disorder), medical conditions indicating chronic activation of the hypothalamic-pituitary-adrenal axis (e.g., Cushing's syndrome), and other life situations associated with elevated risk of chronic stress (e.g., shiftwork). Results from some studies suggest that physical activity, adiposity, and substance abuse may be correlates of hair cortisol concentrations. In contrast to measures of short-term cortisol release (saliva, blood, and urine), cigarette smoking and use of oral contraceptives appear not to be associated with hair cortisol concentrations. Studies of pregnant women indicate increased hair cortisol concentrations across successive trimesters. The study of hair cortisol presents a unique opportunity to assess chronic alterations in cortisol concentrations in epidemiologic studies. Copyright © 2013 Elsevier Inc. All rights reserved.

  8. Optimization of Bolt Stress

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard

    2013-01-01

    The state of stress in bolts and nuts with ISO metric thread design is examined and optimized. The assumed failure mode is fatigue so the applied preload and the load amplitude together with the stress concentrations define the connection strength. Maximum stress in the bolt is found at, the fillet...... under the head, at the thread start or at the thread root. To minimize the stress concentration shape optimization is applied....

  9. EFFECT OF SHORT-TERM CAFFEINE SUPPLEMENTATION ON STRESS RESPONSE AND IMMUNE SYSTEM OF MALE ATHLETES

    Directory of Open Access Journals (Sweden)

    Asghar Tofighi

    2014-03-01

    Full Text Available Vigorous exercise stress might be leading cause of immune system disorders and appearance of acute and chronic inflammation in human body. Caffeine supplementation prior to exercise can be effective on body immune response. This study aimed to evaluate the effect of short-term caffeine supplementation on immune response and stress index in male athletes after an exhaustive aerobic exercise. Materials and methods : In a double-blind study 24 male athletes (endurance runner and triathlon randomly divided in Caffeine supplementation (CAF and Placebo (CON groups. One hour prior to main exhaustive treadmill test (Bruce test CAF group consumed caffeine (6 Mg/BW and CON group received placebo. Blood samples were collected before and immediately after exercise test from anticubital vein. After supplying serum; Cortisol, leukocyte and serum Heat shock protein 72 (Hsp72 concentrations were determined using ELISA method. Paired and independent t student test was used for analysis of inter and intra group differences respectively. Results: serum cortisol and Hsp72 concentrations in CON group was significantly higher than CAF group (P0.05. In addition Mean of variation in CON group was significantly higher than CAF group (P<0.05. Conclusions: Based on study results caffeine supplementation prior to short-term exhaustive aerobic exercise has positive effect on innate immunity and body defensive system.

  10. EFFECT OF SHORT-TERM CAFFEINE SUPPLEMENTATION ON STRESS RESPONSE AND IMMUNE SYSTEM OF MALE ATHLETES

    Directory of Open Access Journals (Sweden)

    Asghar Tofighi

    2014-04-01

    Full Text Available Vigorous exercise stress might be leading cause of immune system disorders and appearance of acute and chronic inflammation in human body. Caffeine supplementation prior to exercise can be effective on body immune response. This study aimed to evaluate the effect of short-term caffeine supplementation on immune response and stress index in male athletes after an exhaustive aerobic exercise. Materials and methods : In a double-blind study 24 male athletes (endurance runner and triathlon randomly divided in Caffeine supplementation (CAF and Placebo (CON groups. One hour prior to main exhaustive treadmill test (Bruce test CAF group consumed caffeine (6 Mg/BW and CON group received placebo. Blood samples were collected before and immediately after exercise test from anticubital vein. After supplying serum; Cortisol, leukocyte and serum Heat shock protein 72 (Hsp72 concentrations were determined using ELISA method. Paired and independent t student test was used for analysis of inter and intra group differences respectively. Results: serum cortisol and Hsp72 concentrations in CON group was significantly higher than CAF group (P0.05. In addition Mean of variation in CON group was significantly higher than CAF group (P<0.05. Conclusions: Based on study results caffeine supplementation prior to short-term exhaustive aerobic exercise has positive effect on innate immunity and body defensive system.

  11. The effective stress concept in saturated sand-clay buffer

    International Nuclear Information System (INIS)

    Graham, J.; Oswell, J.M.; Gray, M.N.

    1992-01-01

    Tests were performed on mixtures of sand and bentonite, to investigate whether the behavior of the mixture can be expressed in terms of effective stresses, defined as the tensor difference between externally applied total stresses and pore water pressures measured outside the cell. Within acceptable bounds of experimental error, the tests show that effective stress can be used to describe consolidation and shear behaviour. However, because part of the effective stress in the clay is derived from net interparticle repulsive (unit) forces seated in diffuse double layers around aggregations of bentonite particles, the applicability of the concept has at this stage been restricted to conditions of constant volume (or possibly constant straining rate), constant chemistry, and constant temperature

  12. Individual and crossover effects of stress on adjustment in medical student marriages.

    Science.gov (United States)

    Katz, J; Monnier, J; Libet, J; Shaw, D; Beach, S R

    2000-07-01

    High-stress individuals may benefit from social support, although their support providers may be adversely affected via stress crossover effects. Individual and crossover effects of perceived stress within medical student marriages (n = 30) were investigated. Perceived spousal support was positively associated with individuals' own marital and emotional adjustment, attenuating stress effects. With regard to crossover effects, medical students' perceived stress was significantly associated with their spouses' emotional adjustment. Further, medical students' own emotional adjustment fully mediated this crossover effect. Results suggest that the contagion of negative affect may serve as a key mechanism through which stress crossover effects operate in marriage.

  13. Interactive effect of biochar and plant growth-promoting bacterial endophytes on ameliorating salinity stress in maize

    DEFF Research Database (Denmark)

    Saleem Akhtar, Saqib; Andersen, Mathias Neumann; Naveed, Muhammad

    2015-01-01

    The objective of this work was to study the interactive effect of biochar and plant growth-promoting endophytic bacteria containing 1-aminocyclopropane-1-carboxylate deaminase and exopolysaccharide activity on mitigating salinity stress in maize (Zea mays L.). The plants were grown in a greenhouse...... under controlled conditions, and were subjected to separate or combined treatments of biochar (0% and 5%, w/w) and two endophytic bacterial strains (Burkholderia phytofirmans (PsJN) and Enterobacter sp. (FD17)) and salinity stress. The results indicated that salinity significantly decreased the growth...... of maize, whereas both biochar and inoculation mitigated the negative effects of salinity on maize performance either by decreasing the xylem Na+ concentration ([Na+]xylem) uptake or by maintaining nutrient balance within the plant, especially when the two treatments were applied in combination. Moreover...

  14. Mental Health Effects of Stress over the Life Span of Refugees.

    Science.gov (United States)

    Hollifield, Michael; Warner, Teddy D; Krakow, Barry; Westermeyer, Joseph

    2018-02-06

    Information about the relative impact of stressful events across the lifespan on the mental health of refugees is needed. Cross-sectional data from a community sample of 135 Kurdish and 117 Vietnamese refugees were fit to a path model about the effects of non-war stress, war-related stress, and post-migration stress on mental health. Kurdish and Vietnamese data were generally consistent with the model. However, war-related stress produced no direct but a large indirect effect through post-migration stress on mental health in Kurds. Vietnamese data indicated a modest direct war-related stress effect but no indirect influence through post-migration stress. Different types of stressful events lead to adverse mental health of displaced refugees in a somewhat group-dependent manner. Implications for prevention and treatment are discussed.

  15. Mental Health Effects of Stress over the Life Span of Refugees

    Directory of Open Access Journals (Sweden)

    Michael Hollifield

    2018-02-01

    Full Text Available Information about the relative impact of stressful events across the lifespan on the mental health of refugees is needed. Cross-sectional data from a community sample of 135 Kurdish and 117 Vietnamese refugees were fit to a path model about the effects of non-war stress, war-related stress, and post-migration stress on mental health. Kurdish and Vietnamese data were generally consistent with the model. However, war-related stress produced no direct but a large indirect effect through post-migration stress on mental health in Kurds. Vietnamese data indicated a modest direct war-related stress effect but no indirect influence through post-migration stress. Different types of stressful events lead to adverse mental health of displaced refugees in a somewhat group-dependent manner. Implications for prevention and treatment are discussed.

  16. Stress State Analysis and Failure Mechanisms of Masonry Columns Reinforced with FRP under Concentric Compressive Load

    Directory of Open Access Journals (Sweden)

    Jiří Witzany

    2016-04-01

    Full Text Available The strengthening and stabilization of damaged compressed masonry columns with composites based on fabrics of high-strength fibers and epoxy resin, or polymer-modified cement mixtures, belongs to novel, partially non-invasive and reversible progressive methods. The stabilizing and reinforcing effect of these fabrics significantly applies to masonry structures under concentric compressive loading whose failure mechanism is characterized by the appearance and development of vertical tensile cracks accompanied by an increase in horizontal masonry strain. During the appearance of micro and hairline cracks (10−3 to 10−1 mm, the effect of non-pre-stressed wrapping composite is very small. The favorable effect of passive wrapping is only intensively manifested after the appearance of cracks (10−1 mm and bigger at higher loading levels. In the case of “optimum” reinforcement of a masonry column, the experimental research showed an increase in vertical displacements δy (up to 247%, horizontal displacements δx (up to 742% and ultimate load-bearing capacity (up to 136% compared to the values reached in unreinforced masonry columns. In the case of masonry structures in which no intensive “bed joint filler–masonry unit” interaction occurs, e.g., in regular coursed masonry with little differences in the mechanical characteristics of masonry units and the binder, the reinforcing effect of the fabric applies only partially.

  17. Effects of cadmium on life-cycle parameters in a multi-generation study with Chironomus riparius following a pre-exposure of populations to two different tributyltin concentrations for several generations.

    Science.gov (United States)

    Vogt, Christian; Hess, Maren; Nowak, Carsten; Diogo, João Barateiro; Oehlmann, Jörg; Oetken, Matthias

    2010-10-01

    So far only a few studies have been performed to assess the effects of dynamic pollutant exposure on life-history parameters of invertebrates. In a previous multi-generation approach with the midge Chironomus riparius we tested if a chronic tributyltin pre-exposure alters the ability of a population to cope with subsequent cadmium stress. In the experiment two separate chironomid populations were exposed via sediments to different TBT-concentrations (4.46 and 8.93 μg Sn/kg dw) for several generations, followed by subsequent cadmium exposure (1.2 mg Cd/kg dw) for three generations. While the TBT-exposure to 4.46 μg Sn/kg dw had only small effects on the development and reproduction of C. riparius the higher TBT-concentration of 8.93 μg Sn/kg dw led to negative effects on life-history traits. Therefore, a higher adverse effect of the higher TBT-concentration and thus a higher susceptibility to other stressors could be assumed. Within, this paper only the results of the second stressor experiment were presented; clear effects of Cd on development and reproduction of C. riparius were determined independent of the pre-exposure scenario. While no differences in Cd-sensitivity were found between the population without pre-exposure to TBT and the population pre-exposed to the low TBT-concentration (4.46 μg Sn/kg dw), the pre-exposure of midges to the higher TBT-concentration (8.93 μg Sn/kg dw) resulted in a significantly higher susceptibility to subsequent Cd-stress. These results document that the exposure history may influence the reaction to altered chemical stress. Our findings are relevant to understand and predict the evolutionary fate of populations in rapidly changing, human-impacted environments. However, the fact that chemical-induced reduced genetic diversity, which is not necessarily linked to genetic adaptation, leads to a reduced fitness under altered stress conditions, is to our knowledge a novel finding.

  18. Labour analgesia with intrathecal fentanyl decreases maternal stress.

    Science.gov (United States)

    Cascio, M; Pygon, B; Bernett, C; Ramanathan, S

    1997-06-01

    Lumbar epidural analgesia (LEA) decreases maternal stress as measured by maternal circulating plasma catecholamine concentrations. Intrathecal fentanyl (ITF) provides effective labour analgesia but its effect on maternal epinephrine (Epi) and norepinephrine (NE) concentrations is not known. This study assesses whether ITF reduces maternal stress in the same manner as conventional LEA. Twenty-four healthy women in active labour received either 25 micrograms ITF (n = 12) or epidural lidocaine 1.5% (n = 12) for analgesia. Venous blood samples were collected before anaesthesia and at five minute intervals for 30 min following anaesthesia for the measurement of plasma Epi and NE by high performance liquid chromatography. Maternal blood pressure (BP), heart rate (HR), visual analog scores (VAS) to pain and pruritus were recorded at the same time. Both ITF and LEA decreased pain VAS scores, maternal BP, and plasma Epi concentrations with only minimal effects on plasma NE concentrations. Intrathecal fentanyl (ITF) and LEA reduced plasma epi to a similar extent, with ITF reducing the levels slightly faster than LEA. Intrathecal fentanyl(ITF) and LEA reduced plasma Epi concentrations by 52% and 51%, respectively (P value < 0.01). We conclude that ITF is as effective as LEA in producing pain relief in the labouring patient. Intrathecal Fentanyl (ITF) is also capable of reducing maternal plasma epinephrine concentration, thus avoiding the possibly deleterious side effects of excess amounts of this catecholamine during labour.

  19. Prosocial Behavior Mitigates the Negative Effects of Stress in Everyday Life.

    Science.gov (United States)

    Raposa, Elizabeth B; Laws, Holly B; Ansell, Emily B

    2016-07-01

    Recent theories of stress reactivity posit that, when stressed, individuals tend to seek out opportunities to affiliate with and nurture others in order to prevent or mitigate the negative effects of stress. However, few studies have tested empirically the role of prosocial behavior in reducing negative emotional responses to stress. The current analyses used daily diary data to investigate whether engaging in prosocial behavior buffered the negative effects of naturally-occurring stressors on emotional well-being. Results showed that on a given day, prosocial behavior moderated the effects of stress on positive affect, negative affect, and overall mental health. Findings suggest that affiliative behavior may be an important component of coping with stress, and indicate that engaging in prosocial behavior might be an effective strategy for reducing the impact of stress on emotional functioning.

  20. Asymmetrical cross-talk between the endoplasmic reticulum stress and oxidative stress caused by dextrose.

    Science.gov (United States)

    Mooradian, Arshag D; Onstead-Haas, Luisa; Haas, Michael J

    2016-01-01

    Oxidative and endoplasmic reticulum (ER) stresses are implicated in premature cardiovascular disease in people with diabetes. The aim of the present study was to characterize the nature of the interplay between the oxidative and ER stresses to facilitate the development of therapeutic agents that can ameliorate these stresses. Human coronary artery endothelial cells were treated with varying concentrations of dextrose in the presence or absence of three antioxidants (alpha tocopherol, ascorbate and ebselen) and two ER stress modifiers (ERSMs) (4-phenylbutyrate and taurodeoxycholic acid). ER stress was measured using the placental alkaline phosphatase assay and superoxide (SO) generation was measured using the superoxide-reactive probe 2-methyl-6-(4-methoxyphenyl)-3,7-dihydroimidazo[1,2-A]pyrazin-3-one hydrochloride chemiluminescence. The SO generation was increased with increasing concentrations of dextrose. The ER stress was increased with both low (0 and 2.75 mM) and high (13.75 and 27.5 mM) concentrations of dextrose. The antioxidants inhibited the dextrose induced SO production while in high concentrations they aggravated ER stress. The ERSM reduced ER stress and potentiated the efficacy of the three antioxidants. Tunicamycin-induced ER stress was not associated with increased SO generation. Time course experiments with a high concentration of dextrose or by overexpressing glucose transporter one in endothelial cells revealed that dextrose induced SO generation undergoes adaptive down regulation within 2 h while the ER stress is sustained throughout 72 h of observation. The nature of the cross talk between oxidative stress and ER stress induced by dextrose may explain the failure of antioxidant therapy in reducing diabetes complications. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Effects of combined drought and heavy metal stresses on xylem structure and hydraulic conductivity in red maple (Acer rubrum L.).

    Science.gov (United States)

    de Silva, Nayana Dilini Gardiyehewa; Cholewa, Ewa; Ryser, Peter

    2012-10-01

    The effects of heavy metal stress, drought stress, and their combination on xylem structure in red maple (Acer rubrum) seedlings were investigated in an outdoor pot experiment. As metal-contaminated substrate, a mixture of 1.5% slag with sand was used, with Ni, Cu, Co, and Cr as the main contaminants. Plants grown on contaminated substrate had increased leaf metal concentrations. The two stresses reduced plant growth in an additive manner. The effects of metal and drought stresses on xylem characteristics were similar to each other, with a reduced proportion of xylem tissue, reduced conduit density in stems, and reduced conduit size in the roots. This resulted, in both stems and roots, in reductions in hydraulic conductance, xylem-specific conductivity, and leaf-specific conductivity. The similarity of the responses to the two stresses suggests that the plants' response to metals was actually a drought response, probably due to the reduced water uptake capacity of the metal-exposed roots. The only plant responses specific to metal stress were decreasing trends of stomatal density and chlorophyll content. In conclusion, the exposure to metals aggravates water stress in an additive manner, making the plants more vulnerable to drought.

  2. Interaction between diffusion and chemical stresses

    International Nuclear Information System (INIS)

    Yang Fuqian

    2005-01-01

    The present work studies the interaction between chemical stresses and diffusion. A new relation between hydrostatic stress and concentration of solute atoms is established. For a solid free of action of body force, the Laplacian of the hydrostatic stress is proportional to the Laplacian of the concentration of solute atoms, that is, deviation of the hydrostatic stress from its local average is proportional to deviation of the local concentration of solute atoms. A general relationship among surface concentration of solute atoms, normal stress and surface deformation of a solid is then derived, in which the normal stress is dependent on the mean curvature of the undeformed surface and tangential components of the surface displacement. A closed-form solution of the steady state concentration of solute atoms in a thin plate is obtained. It turns out that linear distribution of solute atoms in the plate is non-existent due to the interaction between chemical stresses and diffusion

  3. Protective Effect of Humic acid and Chitosan on Radish (Raphanus sativus, L. var. sativus Plants Subjected to Cadmium Stress

    Directory of Open Access Journals (Sweden)

    A.M. EL-Gahmery

    2011-05-01

    Full Text Available BackgroundHumic acid or chitosan has been shown to increase plant growth, yield and improving physiological processes in plant, but its roles on alleviating the harmful effect of cadmium on plant growth and some physiological processes in plants is very rare. Pot experiments were conducted to study the role of 100 and 200 mg/kg dry soil from either humic acid or chitosan on counteracted the harmful effects of cadmium levels (100 and 150 mg/kg dry soil on radish plant growth and some physiological charactersResultsCadmium at 100 and 150 mg kg-1 soil decreased significantly length, fresh and dry weights of shoot and root systems as well as leaf number per plant in both seasons. Chlorophyll, total sugars, nitrogen, phosphorus, potassium, relative water content, water deficit percentage and soluble proteins as well as total amino acids contents were also decreased. Meanwhile, cadmium concentration in plants was increased. On the other hand, application of chitosan or humic acid as soil addition at the concentration of 100 or 200 mg kg-1 increased all the above mentioned parameters and decreased cadmium concentrations in plant tissues. Chitosan at 200 mg kg-1 was the most effective than humic acid at both concentrations in counteracting the harmful effect of cadmium stress on radish plant growth.ConclusionIn conclusion, both natural chelators, in particular, chitosan at 200 mg/kg dry soil can increase the capacity of radish plant to survive under cadmium stress due to chelating the Cd in the soil, and then reduced Cd bio-availability.

  4. ANSYS Modeling of Hydrostatic Stress Effects

    Science.gov (United States)

    Allen, Phillip A.

    1999-01-01

    Classical metal plasticity theory assumes that hydrostatic pressure has no effect on the yield and postyield behavior of metals. Plasticity textbooks, from the earliest to the most modem, infer that there is no hydrostatic effect on the yielding of metals, and even modem finite element programs direct the user to assume the same. The object of this study is to use the von Mises and Drucker-Prager failure theory constitutive models in the finite element program ANSYS to see how well they model conditions of varying hydrostatic pressure. Data is presented for notched round bar (NRB) and "L" shaped tensile specimens. Similar results from finite element models in ABAQUS are shown for comparison. It is shown that when dealing with geometries having a high hydrostatic stress influence, constitutive models that have a functional dependence on hydrostatic stress are more accurate in predicting material behavior than those that are independent of hydrostatic stress.

  5. The effect of obesity on inflammatory cytokine and leptin production following acute mental stress.

    Science.gov (United States)

    Caslin, H L; Franco, R L; Crabb, E B; Huang, C J; Bowen, M K; Acevedo, E O

    2016-02-01

    Obesity may contribute to cardiovascular disease (CVD) risk by eliciting chronic systemic inflammation and impairing the immune response to additional stressors. There has been little assessment of the effect of obesity on psychological stress, an independent risk factor for CVD. Therefore, it was of interest to examine interleukin-6, tumor necrosis factor-α, interleukin-1β (IL-1β), interleukin-1 receptor antagonist (IL-1Ra), and leptin following an acute mental stress task in nonobese and obese males. Twenty college-aged males (21.3 ± 0.56 years) volunteered to participate in a 20-min Stroop color-word and mirror-tracing task. Subjects were recruited for obese (body mass index: BMI > 30) and nonobese (BMI stress task elicited an increase in heart rate, catecholamines, and IL-1β in all subjects. Additionally, acute mental stress increased cortisol concentrations in the nonobese group. There was a significant reduction in leptin in obese subjects 30 min posttask compared with a decrease in nonobese subjects 120 min posttask. Interestingly, the relationship between the percent change in leptin and IL-1Ra at 120 min posttask in response to an acute mental stress task was only observed in nonobese individuals. This is the first study to suggest that adiposity in males may impact leptin and inflammatory signaling mechanisms following acute mental stress. © 2015 Society for Psychophysiological Research.

  6. Nuclear waste treatment - Studying the mixed ion type effects and concentration on the behaviour of oxide dispersions

    International Nuclear Information System (INIS)

    Omokanye, Qanitalillahi; Biggs, Simon

    2007-01-01

    In order to gain good control over a particulate dispersion it is necessary to accurately characterise the strength of inter-particle forces that may be operating. Such control is not routinely used, as yet, in the nuclear industry despite the possible benefits. We are investigating the impact of mixed electrolyte systems, for example NaCl and Na 2 SO 4 , on the stability of oxide simulant particle dispersions. The electro-acoustic zeta potentials and shear yield stresses for concentrated dispersions have been measured across a range of pH conditions and electrolyte concentrations (0.001 M - 1.0 M). This paper summarizes initial data from these studies showing how the shear yield stress of concentrated aqueous oxide particle dispersions, can be adjusted through regulation of pH and the addition of background electrolytes (salt). The yield stress as a function of pH for these dispersions in mixed electrolytes showed a direct correlation with corresponding measurements of the zeta potential. Changes in the background electrolyte concentration or type were seen to cause a shift in the position of the isoelectric point (iep). Measurements of the shear yield stress showed a maximum at the iep corresponding to the position of maximum instability in the suspension. The consequences of these data for the efficient treatment of solid-liquid systems will be discussed. (authors)

  7. Can heavy metal pollution defend seed germination against heat stress? Effect of heavy metals (Cu(2+), Cd(2+) and Hg(2+)) on maize seed germination under high temperature.

    Science.gov (United States)

    Deng, Benliang; Yang, Kejun; Zhang, Yifei; Li, Zuotong

    2016-09-01

    Heavy metal pollution, as well as greenhouse effect, has become a serious threat today. Both heavy metal and heat stresses can arrest seed germination. What response can be expected for seed germination under both stress conditions? Here, the effects of heavy metals (Cu(2+), Cd(2+) and Hg(2+)) on maize seed germination were investigated at 20 °C and 40 °C. Compared with 20 °C, heat stress induced thermodormancy. However, this thermodormancy could be significantly alleviated by the addition of a low concentration of heavy metals. Heavy metals, as well as heat stress induced H2O2 accumulation in germinating seeds. Interestingly, this low concentration of heavy metal that promoted seed germination could be partly blocked by DMTU (a specific ROS scavenger), irrespective of temperature. Accordingly, H2O2 addition reinforced this promoting effect on seed germination, which was induced by a low concentration of heavy metal. Furthermore, we found that the NADPH oxidase derived ROS was required for seed germination promoted by the heavy metals. Subsequently, treatment of seeds with fluridone (a specific inhibitor of ABA) or ABA significantly alleviated or aggravated thermodormancy, respectively. However, this alleviation or aggravation could be partly attenuated by a low concentration of heavy metals. In addition, germination that was inhibited by high concentrations of heavy metals was also partly reversed by fluridone. The obtained results support the idea that heavy metal-mediated ROS and hormone interaction can finally affect the thermodormancy release or not. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Better executive function under stress mitigates the effects of recent life stress exposure on health in young adults.

    Science.gov (United States)

    Shields, Grant S; Moons, Wesley G; Slavich, George M

    2017-01-01

    Executive function is a neuropsychological construct that enables controlled cognitive processing, which has been hypothesized to enhance individuals' resilience to stress. However, little empirical work has directly examined how executive function under different conditions mitigates the negative effects of stress exposure on health. To address this issue, we recruited 110 healthy young adults and assessed their recent life stress exposure, executive function in either a stressful or non-stressful context, and current health complaints. Based on existing research, we hypothesized that individuals exhibiting better executive function following a laboratory-based stressor (but not a control task) would demonstrate weaker associations between recent stress exposure and health because they perceived recent life stressors as being less severe. Consistent with this hypothesis, better executive function during acute stress, but not in the absence of stress, was associated with an attenuated link between participants' recent life stress exposure and their current health complaints. Moreover, this attenuating effect was mediated by lesser perceptions of stressor severity. Based on these data, we conclude that better executive function under stress is associated with fewer health complaints and that these effects may occur by reducing individuals' perceptions of stressor severity. The data thus suggest the possibility of reducing stress-related health problems by enhancing executive function.

  9. Effective stress, friction and deep crustal faulting

    Science.gov (United States)

    Beeler, N.M.; Hirth, Greg; Thomas, Amanda M.; Burgmann, Roland

    2016-01-01

    Studies of crustal faulting and rock friction invariably assume the effective normal stress that determines fault shear resistance during frictional sliding is the applied normal stress minus the pore pressure. Here we propose an expression for the effective stress coefficient αf at temperatures and stresses near the brittle-ductile transition (BDT) that depends on the percentage of solid-solid contact area across the fault. αf varies with depth and is only near 1 when the yield strength of asperity contacts greatly exceeds the applied normal stress. For a vertical strike-slip quartz fault zone at hydrostatic pore pressure and assuming 1 mm and 1 km shear zone widths for friction and ductile shear, respectively, the BDT is at ~13 km. αf near 1 is restricted to depths where the shear zone is narrow. Below the BDT αf = 0 is due to a dramatically decreased strain rate. Under these circumstances friction cannot be reactivated below the BDT by increasing the pore pressure alone and requires localization. If pore pressure increases and the fault localizes back to 1 mm, then brittle behavior can occur to a depth of around 35 km. The interdependencies among effective stress, contact-scale strain rate, and pore pressure allow estimates of the conditions necessary for deep low-frequency seismicity seen on the San Andreas near Parkfield and in some subduction zones. Among the implications are that shear in the region separating shallow earthquakes and deep low-frequency seismicity is distributed and that the deeper zone involves both elevated pore fluid pressure and localization.

  10. Markers of Oxidative Stress in Dogs with Myxomatous Mitral Valve Disease are Influenced by Sex, Neuter Status, and Serum Cholesterol Concentration

    DEFF Research Database (Denmark)

    Reimann, M. J.; Haggstrom, J.; Moller, J. E.

    2017-01-01

    Background Cardiovascular disease has been associated with oxidative stress, which has been suggested to contribute to myocardial remodeling in human patients. Little is known about the relationship between myxomatous mitral valve disease (MMVD) and oxidative stress in dogs. Objective To determin...... with clinical stage of MMVD. Conclusions In conclusion, markers of oxidative stress are associated with sex, BCS, neuter status, and cholesterol. The results cannot confirm a relationship between oxidative stress and clinical stage of the disease in dogs with MMVD.......Background Cardiovascular disease has been associated with oxidative stress, which has been suggested to contribute to myocardial remodeling in human patients. Little is known about the relationship between myxomatous mitral valve disease (MMVD) and oxidative stress in dogs. Objective To determine...... whether clinical stage of MMVD is associated with changes in the plasma concentrations of certain markers of oxidative stress in clinically healthy dogs and dogs with MMVD. Animals Seventy five privately owned dogs: 59 cavalier King Charles Spaniels (CKCS) with different severities of MMVD and 16 dogs...

  11. Effects of prenatal stress on vulnerability to stress in prepubertal and adult rats.

    Science.gov (United States)

    Fride, E; Dan, Y; Feldon, J; Halevy, G; Weinstock, M

    1986-01-01

    This study investigated the hypotheses that unpredictable prenatal stress has effects on the offspring, similar to those induced by perinatal administration of glucocorticoids and increases the vulnerability to stressful situations at adulthood. Rats were exposed to random noise and light stress throughout pregnancy. Offspring were tested for the development of spontaneous alternation behavior (SA) and at adulthood, their response to novel or aversive situations, open field, extinction and punishment following acquisition of an appetitive response and two-way active avoidance, were assessed. In prenatally stressed rats, the development of SA was significantly delayed. On repeated exposure to an open field they were less active; control rats had elevated plasma corticosterone (CCS) on days 2 and 4 of open field exposure, while prenatally stressed rats had significantly raised plasma CCS after each exposure (days 1-8). Furthermore, punishment-induced suppression of an appetitive response was enhanced. Acquisition of active avoidance was faciliated in female but reduced in male prenatally stressed offspring. It is suggested that random prenatal noise and light stress may cause impairment of development of hippocampal function which lasts into adulthood. This impairment is manifested as an increase in vulnerability and a decrease in habituation to stressful stimuli.

  12. Effects of ventilation on hyaluronan and protein concentration in pleural liquid of anesthetized and conscious rabbits.

    Science.gov (United States)

    Wang, P M; Lai-Fook, S J

    1998-01-01

    The hypothesis of this study is that pleural lubrication is enhanced by hyaluronan acting as a boundary lubricant in pleural liquid and by pleural filtration as reflected in changes in protein concentration with ventilation. Anesthetized rabbits were injected intravenously with Evans blue dye and ventilated with 100% O2 at either of two levels of ventilation for 6 h. Postmortem values of hyaluronan, total protein, and Evans blue-dyed albumin (EBA) concentrations in pleural liquid were greater at the higher ventilation, consistent with increases in boundary lubrication, pleural membrane permeability, and pleural filtration. To determine whether these effects were caused by hyperoxia or anesthesia, conscious rabbits were ventilated with either 3% CO2 or room air in a box for 6, 12, or 24 h. Similar to the anesthetized rabbits, pleural liquid hyaluronan concentration after 24 h was higher in the conscious rabbits with the hypercapnic-induced greater ventilation. By contrast, the time course of total protein and EBA in pleural liquid was similar in both groups of conscious rabbits, indicating no effect of ventilation on pleural permeability. The increase in pleural liquid hyaluronan concentration might be the result of mesothelial cell stimulation by a ventilation-induced increase in pleural liquid shear stress.

  13. Stress Associated With Habitat Quality And Group Living In Ravens

    OpenAIRE

    Mueller, Thomas; Selva, Nuria; Cortes-Avizanda, Ainara; Lemus, Jesús Angel; Blanco, Guillermo; Heinrich, Bernd; Pugacewicz, Eugeniuz; Prins, Erik; Donázar, José A.

    2011-01-01

    Many long-lived avian species adopt life strategies that involve a gregarious way of life at juvenile and sub-adult stages and territoriality during adulthood. However, the potential associated costs of these life styles, such as stress, are poorly understood. Likewise the effects of habitat quality on stress are not well understood. We examined the effects of group living, habitat quality, sex, and parasite load on the baseline concentration of faecal stress hormone (corticosterone) metaboli...

  14. Restraint stress in lactating mice alters the levels of sulfur-containing amino acids in milk.

    Science.gov (United States)

    Nishigawa, Takuma; Nagamachi, Satsuki; Ikeda, Hiromi; Chowdhury, Vishwajit S; Furuse, Mitsuhiro

    2018-03-30

    It is well known that maternal stress during the gestation and lactation periods induces abnormal behavior in the offspring and causes a lowering of the offspring's body weight. Various causes of maternal stress during the lactation period, relating to, for example, maternal nutritional status and reduced maternal care, have been considered. However, little is known about the effects on milk of maternal stress during the lactation period. The current study aimed to determine whether free amino acids, with special reference to sulfur-containing amino acids in milk, are altered by restraint stress in lactating mice. The dams in the stress group were restrained for 30 min at postnatal days 2, 4, 6, 8, 10 and 12. Restraint stress caused a reduction in the body weight of lactating mice. The concentration of taurine and cystathionine in milk was significantly higher in the stress group, though stress did not alter their concentration in maternal plasma. The ratio of taurine concentration in milk to its concentration in maternal plasma was significantly higher in the stress group, suggesting that stress promoted taurine transportation into milk. Furthermore, taurine concentration in milk was positively correlated with corticosterone levels in plasma. In conclusion, restraint stress in lactating mice caused the changes in the metabolism and in the transportation of sulfur-containing amino acids and resulted in higher taurine concentration in milk. Taurine concentration in milk could also be a good parameter for determining stress status in dams.

  15. Effects of heat stress on baroreflex function in humans

    Science.gov (United States)

    Crandall, Craig G.; Cui, Jian; Wilson, Thad E.

    2003-01-01

    INTRODUCTION: Heat stress significantly reduces orthostatic tolerance in humans. The mechanism(s) causing this response remain unknown. The purpose of this review article is to present data pertaining to the hypothesis that reduced orthostatic tolerance in heat stressed individuals is a result of heat stress induced alterations in baroflex function. METHODS: In both normothermic and heat stressed conditions baroreflex responsiveness was assessed via pharmacological and non-pharmacological methods. In addition, the effects of heat stress on post-synaptic vasoconstrictor responsiveness were assessed. RESULTS: Generally, whole body heating did not alter baroreflex sensitivity defined as the gain of the linear portion of the baroreflex curve around the operating point. However, whole body heating shifted the baroreflex curve to the prevailing (i.e. elevated) heart rate and muscle sympathetic nerve activity. Finally, the heat stress impaired vasoconstrictor responses to exogenous administration of adrenergic agonists. CONCLUSION: Current data do not support the hypothesis that reduced orthostatic tolerance associated with heat stress in humans is due to impaired baroreflex responsiveness. This phenomenon may be partially due to the effects of heat stress on reducing vasoconstrictor responsiveness.

  16. Toxic and genotoxic effects of Roundup on tadpoles of the Indian skittering frog (Euflictis cyanophlyctis) in the presence and absence of predator stress.

    Science.gov (United States)

    Yadav, Sushama Singh; Giri, Sarbani; Singha, Utsab; Boro, Freeman; Giri, Anirudha

    2013-05-15

    Glyphosate, a post emergent herbicide, has become the backbone of no-till agriculture and is considered safe for animals. However, the impact of glyphosate on non-target organisms, especially on amphibians, is the subject of major concern and debate in recent times. We examined the toxic and genotoxic effects of Roundup, a commercial formulation of glyphosate, in the tadpoles of the Indian skittering frog (Euflictis cyanophlyctis). Roundup at different concentrations (0, 1, 2, 3, 4 and 8mg acid equivalent (ae)/L), tested in a 2×6 factorial design in the presence and absence of predator stress, induced concentration-dependent lethality in tadpoles. The 96-h LC50 for Roundup in the absence and presence of predator stress were 3.76mgae/L and 3.39mgae/L, respectively. The 10-day LC50 value for Roundup was significantly lower, 2.12mgae/L and 1.91mgae/L in the absence and presence of predator stress, respectively. Lower concentrations of Roundup (1, 2 and 3mgae/L) induced the formation of micronuclei (MN) in the erythrocytes of tadpoles at 24-h (F3,56=10.286, p<0.001), 48-h (F3,56=48.255, p<0.001), 72-h (F3,56=118.933, p<0.001) and 96-h (F3,56=85.414, p<0.001) in a concentration-dependent manner. Presence of predator stress apparently increased the toxicity and genotoxicity of Roundup; but these effects were not statistically significant. These findings suggest that Roundup at environmentally relevant concentrations has lethal and genotoxic impact on E. cyanophlyctis; which may have long-term fitness consequence to the species. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Stress Effects on Stop Bursts in Five Languages

    Directory of Open Access Journals (Sweden)

    Marija Tabain

    2016-11-01

    Full Text Available This study examines the effects of stress on the stop burst in five languages differing in number of places of articulation, as reflected in burst duration, spectral centre of gravity, and ­spectral standard deviation. The languages studied are English (three places of articulation /p t k/, the Indonesian language Makasar (four places /p t c k/, and the Central Australian languages ­Pitjantjatjara, Warlpiri (both five places /p t ʈ c k/, and Arrernte (six places /p t̪ t ʈ c k/. We find that languages differ in how they manifest stress on the consonant, with Makasar not ­showing any effect of stress at all, and Warlpiri showing an effect on burst duration, but not on the ­spectral measures. For the other languages, the velar /k/ has a “darker” quality (i.e., lower spectral centre of gravity, and/or a less diffuse spectrum (i.e., lower standard deviation under stress; while the alveolar /t/ has a “lighter” quality under stress. In addition, the dental /t̪/ has a more diffuse spectrum under stress. We suggest that this involves enhancement of the features [grave] and [diffuse] under stress, with velars being [+grave] and [–diffuse], alveolars being [–grave], and dentals being [+diffuse]. We discuss the various possible spectral effects of enhancement of these features. Finally, in the languages with five or six places of articulation, the stop burst is longer only for the palatal /c/ and the velar /k/, which have intrinsically long burst durations, and not for the anterior coronals /t̪ t ʈ/, which have intrinsically short burst durations. We suggest that in these systems, [burst duration] is a feature that separates these two groups of consonants.

  18. Influence of effective stress on swelling pressure of expansive soils

    Directory of Open Access Journals (Sweden)

    Baille Wiebke

    2016-01-01

    Full Text Available The volume change and shear strength behaviour of soils are controlled by the effective stress. Recent advances in unsaturated soil mechanics have shown that the effective stress as applicable to unsaturated soils is equal to the difference between the externally applied stress and the suction stress. The latter can be established based on the soil-water characteristic curve (SWCC of the soil. In the present study, the evolution of swelling pressure in compacted bentonite-sand mixtures was investigated. Comparisons were made between magnitudes of applied suction, suction stress, and swelling pressure.

  19. Grain boundary chromium concentration effects on the IGSCC and IASCC of austenitic stainless steels

    International Nuclear Information System (INIS)

    Bruemmer, S.M.; Arey, B.W.; Charlot, L.A.

    1993-08-01

    Comparisons are made between grain boundary composition and intergranular stress corrosion cracking (IGSCC) of 304 and 309 austenitic stainless steels in high-temperature water environments. Chromium depletion had the dominant effect on cracking resistance with the extent of IG cracking controlled by the interfacial chromium concentration. The minimum chromium concentration required to promote cracking was a function of the applied strain rate during slow-strain-rate tensile tests in 288 C air-saturated water. Depletion from bulk levels of 18 wt% to ∼13.5 wt% Cr at grain boundaries prompted 100% IG cracking at a strain rate of 1 x 10 -6 s -1 , while embrittlement was observed with only a slight depletion to ∼17 wt% at 2 x 10 -7 s -1 . Insights into critical interfacial compositions promoting IGSCC are discussed in reference to cracking of irradiated stainless steel nuclear reactor core components

  20. Mean stress effects on high-cycle fatigue of Alloy 718

    International Nuclear Information System (INIS)

    Korth, G.E.

    1980-07-01

    This report covers an investigation of the effects of tensile mean stress on the high-cycle fatigue properties of Alloy 718. Three test temperatures (24, 427, and 649 degree C) were employed, and there were tests in both strain and load control. Results were compared with three different models: linear Modified-Goodman, Peterson cubic, and stress-strain parameter. The linear Modified-Goodman model gave good correlation with actual test data for low and moderate mean stress values, but the stress-strain parameter showed excellent correlation over the entire range of possible mean stresses and therefore is recommended for predicting mean stress effects of Alloy 718. 13 refs., 12 figs

  1. Effect of Filter Cake on Physiological Traits and Ear Yield of Sweet Corn under Late Drought Stress Condition

    Directory of Open Access Journals (Sweden)

    aziz karmollachaab

    2017-10-01

    different levels of Filter Cake significantly reduced the plant’s height. Although Mild stress did not have a significant effect on membrane stability index, severe drought stress reduced it about 17.5% compared with non-stress treatments. The osmotic potential in normal conditions was the highest, however, it was decreased with increasing stress. Therefore, in severe stress conditions and treatment without Filter Cake, osmotic potential was -1.71 MPa. Mild and severe drought stress significantly reduced soluble proteins of the leaf by 12.5% and 17.1%, respectively compared with the control. Application of 10 tons per hectare of Filter Cake had no significant effect on sodium ion concentration, but using 20 and 30 tons per hectare of Filter Cake increased the concentration by 39% and 44%, respectivelycompared with the control. The use of 10 tons of Filter Cake in non-stress conditions had no significant effect on Na, but using 20 and 30 tons per hectare of Filter Cake increased the amount of Na by 10% and 13.7%,, respectively compared with the control. In severe stress conditions, the use of 20 and 30 tons per hectare of Filter Cake decreased fresh weight yield by 9% and 14.5%,, respectively. Under non-stress conditions, the use of Filter Cake led to increased dry matter production. In severe stress conditions the use of 10 tons per hectare of Filter Cake did not have significant effects on biological yield, but application of 20 and 30 tons per hectare of Filter Cake decreased biological yield by19% and 23%, respectively compared with treatment without Filter Cake. Conclusion The results showed that: (1 Drought stress reduces the growth and yield of sweet corn and economic benefit in spring planting in Khuzestan province. (2 The use of Filter Cake through physical modification of the soil, causes uniformity of germination and early growth acceleration of product, and in non-stress conditions increases economic performance. (3 In drought stress conditions, the use of

  2. Effect of potassium application in drought-stressed tobacco (Nicotiana rustica L. plants: Comparison of root with foliar application

    Directory of Open Access Journals (Sweden)

    Sara Bahrami-Rad

    2017-12-01

    Full Text Available Effect of potassium (K application through leaves (LA or roots (RA was studied in tobacco plants grown under K deficiency and drought stress conditions. Application of K was effective in improving the shoot growth only under drought conditions, whereas root biomass and length responded under both watering regimes. Under drought conditions, photosynthesis and transpiration activities increased upon K application leading to a reduced water use efficiency. Both RA and LA increased the leaf water potential, relative water content and turgor under both well-watered and drought conditions; RA was more effective than LA in the recovery of leaf turgor. Analyses of water relation parameters in different aged leaves showed lower susceptibility of the middle-aged leaves to both K deficiency and drought stresses than the upper and lower leaves; this phenomenon was accompanied by a more conservative control of water loss in the middle-aged leaves. In contrast, proline was accumulated in the young leaves, and K application increased it further. Although various organic osmolytes were accumulated under the combinative effect of K deficiency and drought stress, they did not exceed the amounts found in the control (well-watered +K plants and were merely a result of the concentration effect. Collectively, our results revealed that the majority of leaf biochemical responses to drought stress are developmentally regulated processes. In addition, the alleviating effect of both RA and LA despite higher water loss indicated that an improved stomatal function upon K application allowed carbohydrates synthesis, thus, enhancing plant growth under water stress.

  3. Targeting the Microbiota-Gut-Brain Axis: Prebiotics Have Anxiolytic and Antidepressant-like Effects and Reverse the Impact of Chronic Stress in Mice.

    Science.gov (United States)

    Burokas, Aurelijus; Arboleya, Silvia; Moloney, Rachel D; Peterson, Veronica L; Murphy, Kiera; Clarke, Gerard; Stanton, Catherine; Dinan, Timothy G; Cryan, John F

    2017-10-01

    The realization that the microbiota-gut-brain axis plays a critical role in health and disease, including neuropsychiatric disorders, is rapidly advancing. Nurturing a beneficial gut microbiome with prebiotics, such as fructo-oligosaccharides (FOS) and galacto-oligosaccharides (GOS), is an appealing but underinvestigated microbiota manipulation. Here we tested whether chronic prebiotic treatment modifies behavior across domains relevant to anxiety, depression, cognition, stress response, and social behavior. C57BL/6J male mice were administered FOS, GOS, or a combination of FOS+GOS for 3 weeks prior to testing. Plasma corticosterone, microbiota composition, and cecal short-chain fatty acids were measured. In addition, FOS+GOS- or water-treated mice were also exposed to chronic psychosocial stress, and behavior, immune, and microbiota parameters were assessed. Chronic prebiotic FOS+GOS treatment exhibited both antidepressant and anxiolytic effects. Moreover, the administration of GOS and the FOS+GOS combination reduced stress-induced corticosterone release. Prebiotics modified specific gene expression in the hippocampus and hypothalamus. Regarding short-chain fatty acid concentrations, prebiotic administration increased cecal acetate and propionate and reduced isobutyrate concentrations, changes that correlated significantly with the positive effects seen on behavior. Moreover, FOS+GOS reduced chronic stress-induced elevations in corticosterone and proinflammatory cytokine levels and depression-like and anxiety-like behavior in addition to normalizing the effects of stress on the microbiota. Taken together, these data strongly suggest a beneficial role of prebiotic treatment for stress-related behaviors. These findings strengthen the evidence base supporting therapeutic targeting of the gut microbiota for brain-gut axis disorders, opening new avenues in the field of nutritional neuropsychopharmacology. Copyright © 2017 Society of Biological Psychiatry. Published by

  4. Social support moderates the effects of stress on sleep in adolescents.

    Science.gov (United States)

    van Schalkwijk, Frank J; Blessinga, Agaath N; Willemen, Agnes M; Van Der Werf, Ysbrand D; Schuengel, Carlo

    2015-08-01

    Academic expectations and demands become primary sources of stress during adolescence, negatively affecting sleep. To cope with stress, adolescents may turn to social support figures. The present study tested the extent of main and moderating effects of various sources of social support on the association between stress and sleep. Adolescents (n = 202, meanage 14.6 years, standard deviation = 0.71) reported on academic stress, sleep, and support using questionnaires during a low- and high-stress period, defined by the absence or presence of examinations, respectively. Inquiries were made regarding social support from parents, friends, and class supervisor. During both stress periods, academic stress was associated negatively with sleep quality and positively with sleep reduction. Social support increased sleep quality and lowered sleep reduction. In addition, social support moderated the effects of academic stress on sleep, thus improving sleep quality and lowering sleep reduction. Moderating effects were stronger during a period of high stress. The present study showed that adolescents can benefit from stress moderation through social support by improvements of sleep quality and sleep reduction. Such moderating effects should be taken into account when studying stress and sleep. Implications and recommendations based on these findings are discussed. © 2015 European Sleep Research Society.

  5. Cadmium stress in wheat seedlings: growth, cadmium accumulation and photosynthesis

    DEFF Research Database (Denmark)

    Ci, Dunwei; Jiang, Dong; Wollenweber, Bernd

    2010-01-01

    parameters were generally depressed by Cd stress, especially under the high Cd concentrations. Cd concentration and accumulation in both shoots and roots increased with increasing external Cd concentrations. Relationships between corrected parameters of growth, photosynthesis and fluorescence and corrected......Seedlings of wheat (Triticum aestivum L.) cultivars Jing 411, Jinmai 30 and Yangmai 10 were exposed to 0, 10, 20, 30, 40 or 50 μM of CdCl2 in a solution culture experiment. The effects of cadmium (Cd) stress on wheat growth, leaf photon energy conversion, gas exchange, and Cd accumulation in wheat...

  6. Delayed memory effects after intense stress in Special Forces candidates: exploring path processes between cortisol secretion and memory recall.

    Science.gov (United States)

    Taverniers, John; Taylor, Marcus K; Smeets, Tom

    2013-05-01

    The aim of this paper is twofold. First, it explores delayed effects of high endogenously evoked cortisol concentrations on visuo-spatial declarative memory. Subsequently, it applies multiple mediation (MM) analyses to reveal path processes between stress and cognitive performance in a sample of 24 male Special Forces (SF) candidates (mean age = 27.0 years, SD = 4.1). The SF candidates were randomly assigned to a control (n = 12) or an intense stress group (n = 12), and cortisol secretion for the intense stress condition was triggered by a brusque 60 min prisoner of war exercise. Stress exposure provoked robust increases in cortisol concentrations and a significant decline in immediate recall performance, measured with the Rey-Osterrieth Complex Figure (ROCF). The relative retrieval differences in regard to the ROCF persisted even after a recovery period of 24 h, as both groups showed similar levels of memory decline over 24 h. Next, the study applied a MM design that involved distribution-independent asymptotic and resampling strategies to extend traditional bivariate analyses. MM results showed that ROCF performance was mediated by increases in cortisol concentrations. Considering the studied variables, the current analysis was the first to provide statistical support for the generally accepted thesis that cortisol secretion in itself, rather than subjective strain or the experimental treatment, affects cognitive performance. The revelation of such path processes is important because it establishes process identification and may refine existing paradigms.

  7. Effects of nutrient and light stress on some morphological ...

    African Journals Online (AJOL)

    Tomato seedlings were subjected to light and nutrient stress to determine the effects of each of these stress factors as well as their combined effects on some morphological parameters of the plant. A two-way Analysis of Variance (ANOVA) carried out on the data obtained showed that light produced significant effect on all ...

  8. Behavioral effects of chronic adolescent stress are sustained and sexually dimorphic

    Science.gov (United States)

    Bourke, Chase H.; Neigh, Gretchen N.

    2011-01-01

    Evidence suggests that women are more susceptible to stress-related disorders than men. Animal studies demonstrate a similar female sensitivity to stress and have been used to examine the underlying neurobiology of sex-specific effects of stress. Although our understanding of the sex-specific effects of chronic adolescent stress has grown in recent years, few studies have reported the effects of adolescent stress on depressive-like behavior. The purpose of this study was to determine if a chronic mixed modality stressor (consisting of isolation, restraint, and social defeat) during adolescence (PND37-49) resulted in differential and sustained changes in depressive-like behavior in male and female Wistar rats. Female rats exposed to chronic adolescent stress displayed decreased sucrose consumption, hyperactivity in the elevated plus maze, decreased activity in the forced swim test, and a blunted corticosterone response to an acute forced swim stress compared to controls during both adolescence (PND48-57) and adulthood (PND96-104). Male rats exposed to chronic adolescent stress did not manifest significant behavioral changes at either the end of adolescence or in adulthood. These data support the proposition that adolescence may be a stress sensitive period for females and exposure to stress during adolescence results in behavioral effects that persist in females. Studies investigating the sex-specific effects of chronic adolescent stress may lead to a better understanding of the sexually dimorphic incidence of depressive and anxiety disorders in humans and ultimately improve prevention and treatment strategies. PMID:21466807

  9. Micromagnetic modeling of the effects of stress on magnetic properties

    International Nuclear Information System (INIS)

    Zhu, B.; Lo, C. C. H.; Lee, S. J.; Jiles, D. C.

    2001-01-01

    A micromagnetic model has been developed for investigating the effect of stress on the magnetic properties of thin films. This effect has been implemented by including the magnetoelastic energy term into the Landau - Lifshitz - Gilbert equation. Magnetization curves of a nickel film were calculated under both tensile and compressive stresses of various magnitudes applied along the field direction. The modeling results show that coercivity increased with increasing compressive stress while remanence decreased with increasing tensile stress. The results are in agreement with the experimental data in the literature and can be interpreted in terms of the effects of the applied stress on the irreversible rotation of magnetic moments during magnetization reversal under an applied field. [copyright] 2001 American Institute of Physics

  10. Protective Effects of Maillard Reaction Products of Whey Protein Concentrate against Oxidative Stress through an Nrf2-Dependent Pathway in HepG2 Cells.

    Science.gov (United States)

    Pyo, Min Cheol; Yang, Sung-Yong; Chun, Su-Hyun; Oh, Nam Su; Lee, Kwang-Won

    2016-09-01

    Whey protein concentrate (WPC), which contains α-lactalbumin and β-lactoglobulin, is utilized widely in the food industry. The Maillard reaction is a complex reaction that produces Maillard reaction products (MRPs), which are associated with the formation of antioxidant compounds. In this study, the hepatoprotection activity of MRPs of WPC against oxidative stress through the nuclear factor-E2-related factor 2 (Nrf2)-dependent antioxidant pathway in HepG2 cells was examined. Glucose-whey protein concentrate conjugate (Glc-WPC) was obtained from Maillard reaction between WPC and glucose. The fluorescence intensity of Glc-WPC increased after 7 d compared to native WPC, and resulted in loss of 48% of the free amino groups of WPC. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns of Glc-WPC showed the presence of a high-molecular-weight portion. Treatment of HepG2 cells with Glc-WPC increased cell viability in the presence of oxidative stress, inhibited the generation of intracellular reactive oxygen species by tert-butyl hydroperoxide (t-BHP), and increased the glutathione level. Nrf2 translocation and Nrf2, reduced nicotinamide adenine dinucleotide phosphate (NAD(P)H)-quinone oxidoreductase 1 (NOQ1), heme oxygenase-1 (HO-1), glutamate-L-cysteine ligase (GCL)M and GCLC mRNA levels were increased by Glc-WPC. Also, Glc-WPC increased the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 and c-Jun N-terminal kinase (JNK). The results of this study demonstrate that Glc-WPC activates the Nrf2-dependent pathway through the phosphorylation of ERK1/2 and JNK in HepG2 cells, and induces production of antioxidant enzymes and phase II enzymes.

  11. Nature-Based Stress Management Course for Individuals at Risk of Adverse Health Effects from Work-Related Stress—Effects on Stress Related Symptoms, Workability and Sick Leave

    Directory of Open Access Journals (Sweden)

    Eva Sahlin

    2014-06-01

    Full Text Available Sick leave due to stress-related disorders is increasing in Sweden after a period of decrease. To avoid that individuals living under heavy stress develop more severe stress-related disorders, different stress management interventions are offered. Self-assessed health, burnout-scores and well-being are commonly used as outcome measures. Few studies have used sick-leave to compare effects of stress interventions. A new approach is to use nature and garden in a multimodal stress management context. This study aimed to explore effects on burnout, work ability, stress-related health symptoms, and sick leave for 33 women participating in a 12-weeks nature based stress management course and to investigate how the nature/garden activities were experienced. A mixed method approach was used. Measures were taken at course start and three follow-ups. Results showed decreased burnout-scores and long-term sick leaves, and increased work ability; furthermore less stress-related symptoms were reported. Tools and strategies to better handle stress were achieved and were widely at use at all follow-ups. The garden and nature content played an important role for stress relief and for tools and strategies to develop. The results from this study points to beneficial effects of using garden activities and natural environments in a stress management intervention.

  12. Nature-Based Stress Management Course for Individuals at Risk of Adverse Health Effects from Work-Related Stress—Effects on Stress Related Symptoms, Workability and Sick Leave

    Science.gov (United States)

    Sahlin, Eva; Ahlborg, Gunnar; Vega Matuszczyk, Josefa; Grahn, Patrik

    2014-01-01

    Sick leave due to stress-related disorders is increasing in Sweden after a period of decrease. To avoid that individuals living under heavy stress develop more severe stress-related disorders, different stress management interventions are offered. Self-assessed health, burnout-scores and well-being are commonly used as outcome measures. Few studies have used sick-leave to compare effects of stress interventions. A new approach is to use nature and garden in a multimodal stress management context. This study aimed to explore effects on burnout, work ability, stress-related health symptoms, and sick leave for 33 women participating in a 12-weeks nature based stress management course and to investigate how the nature/garden activities were experienced. A mixed method approach was used. Measures were taken at course start and three follow-ups. Results showed decreased burnout-scores and long-term sick leaves, and increased work ability; furthermore less stress-related symptoms were reported. Tools and strategies to better handle stress were achieved and were widely at use at all follow-ups. The garden and nature content played an important role for stress relief and for tools and strategies to develop. The results from this study points to beneficial effects of using garden activities and natural environments in a stress management intervention. PMID:25003175

  13. Biological effects of environmentally relevant concentrations of the pharmaceutical Triclosan in the marine mussel Perna perna (Linnaeus, 1758)

    Energy Technology Data Exchange (ETDEWEB)

    Sanzi Cortez, Fernando, E-mail: lecotox@unisanta.br [Instituto de Pesquisas Energeticas e Nucleares IPEN-CNEN/SP, 05508-000 Sao Paulo, SP (Brazil); Laboratorio de Ecotoxicologia, Universidade Santa Cecilia, 11045-907 Santos, SP (Brazil); Dias Seabra Pereira, Camilo [Laboratorio de Ecotoxicologia, Universidade Santa Cecilia, 11045-907 Santos, SP (Brazil); Instituto do Mar, Universidade Federal de Sao Paulo, 11030-400 Santos, SP (Brazil); Ramos Santos, Aldo Ramos [Laboratorio de Ecotoxicologia, Universidade Santa Cecilia, 11045-907 Santos, SP (Brazil); Cesar, Augusto; Choueri, Rodrigo Brasil [Laboratorio de Ecotoxicologia, Universidade Santa Cecilia, 11045-907 Santos, SP (Brazil); Instituto do Mar, Universidade Federal de Sao Paulo, 11030-400 Santos, SP (Brazil); Martini, Gisela de Assis [Laboratorio de Ecotoxicologia, Universidade Santa Cecilia, 11045-907 Santos, SP (Brazil); Bohrer-Morel, Maria Beatriz [Instituto de Pesquisas Energeticas e Nucleares IPEN-CNEN/SP, 05508-000 Sao Paulo, SP (Brazil)

    2012-09-15

    Triclosan (5-Chloro-2-(2,4-dichlorophenoxy) phenol) is an antibacterial compound widely employed in pharmaceuticals and personal care products. Although this emerging compound has been detected in aquatic environments, scarce information is found on the effects of Triclosan to marine organisms. The aim of this study was to evaluate the toxicity of a concentration range of Triclosan through fertilization assay (reproductive success), embryo-larval development assay (early life stage) and physiological stress (Neutral Red Retention Time assay - NRRT) (adult stage) in the marine sentinel organism Perna perna. The mean inhibition concentrations for fertilization (IC{sub 50} = 0.490 mg L{sup -1}) and embryo-larval development (IC{sub 50} = 0.135 mg L{sup -1}) tests were above environmental relevant concentrations (ng L{sup -1}) given by previous studies. Differently, significant reduction on NRRT results was found at 12 ng L{sup -1}, demonstrating the current risk of the continuous introduction of Triclosan into aquatic environments, and the need of ecotoxicological studies oriented by the mechanism of action of the compound. - Highlights: Black-Right-Pointing-Pointer Triclosan causes biological adverse effects at environmental relevant concentrations. Black-Right-Pointing-Pointer Mechanisms of action oriented assays were more sensitive to detect biological damages. Black-Right-Pointing-Pointer Currently there is environmental risks concerned Triclosan in aquatic ecosystems. - Triclosan causes biological adverse effects at environmentally relevant concentrations.

  14. Biological effects of environmentally relevant concentrations of the pharmaceutical Triclosan in the marine mussel Perna perna (Linnaeus, 1758)

    International Nuclear Information System (INIS)

    Sanzi Cortez, Fernando; Dias Seabra Pereira, Camilo; Ramos Santos, Aldo Ramos; Cesar, Augusto; Choueri, Rodrigo Brasil; Martini, Gisela de Assis; Bohrer-Morel, Maria Beatriz

    2012-01-01

    Triclosan (5-Chloro-2-(2,4-dichlorophenoxy) phenol) is an antibacterial compound widely employed in pharmaceuticals and personal care products. Although this emerging compound has been detected in aquatic environments, scarce information is found on the effects of Triclosan to marine organisms. The aim of this study was to evaluate the toxicity of a concentration range of Triclosan through fertilization assay (reproductive success), embryo-larval development assay (early life stage) and physiological stress (Neutral Red Retention Time assay - NRRT) (adult stage) in the marine sentinel organism Perna perna. The mean inhibition concentrations for fertilization (IC 50 = 0.490 mg L −1 ) and embryo-larval development (IC 50 = 0.135 mg L −1 ) tests were above environmental relevant concentrations (ng L −1 ) given by previous studies. Differently, significant reduction on NRRT results was found at 12 ng L −1 , demonstrating the current risk of the continuous introduction of Triclosan into aquatic environments, and the need of ecotoxicological studies oriented by the mechanism of action of the compound. - Highlights: ► Triclosan causes biological adverse effects at environmental relevant concentrations. ► Mechanisms of action oriented assays were more sensitive to detect biological damages. ► Currently there is environmental risks concerned Triclosan in aquatic ecosystems. - Triclosan causes biological adverse effects at environmentally relevant concentrations.

  15. Effect of transient scrotal hyperthermia on sperm parameters, seminal plasma biochemical markers, and oxidative stress in men

    Directory of Open Access Journals (Sweden)

    Meng Rao

    2015-01-01

    Full Text Available In this experimental prospective study, we aimed to analyze the effect of transient scrotal hyperthermia on the male reproductive organs, from the perspective of sperm parameters, semen plasma biochemical markers, and oxidative stress, to evaluate whether different frequencies of heat exposure cause different degrees of damage to spermatogenesis. Two groups of volunteers (10 per group received testicular warming in a 43°C water bath 10 times, for 30 min each time: group 1: 10 consecutive days; group 2: once every 3 days. Sperm parameters, epididymis and accessory sex gland function, semen plasma oxidative stress and serum sex hormones were tested before treatment and in the 16-week recovery period after treatment. At last, we found an obvious reversible decrease in sperm concentration (P = 0.005 for Group 1 and P= 0.008 for Group 2 when the minimums were compared with baseline levels, the same below, motility (P = 0.009 and 0.021, respectively, the hypoosmotic swelling test score (P = 0.007 and 0.008, respectively, total acrosin activity (P = 0.018 and 0.009, respectively, and an increase in the seminal plasma malondialdehyde concentration (P = 0.005 and 0.017, respectively. The decrease of sperm concentration was greater for Group 2 than for Group 1 (P = 0.031. We concluded that transient scrotal hyperthermia seriously, but reversibly, negatively affected the spermatogenesis, oxidative stress may be involved in this process. In addition, intermittent heat exposure more seriously suppresses the spermatogenesis compared to consecutive heat exposure. This may be indicative for clinical infertility etiology analysis and the design of contraceptive methods based on heat stress.

  16. Effect of personal and work stress on burnout, job satisfaction and ...

    African Journals Online (AJOL)

    Abstract. The majority of studies to date have focused on the effects of work stress in the nursing environment, with the effect of personal stress in nursing being less explored. This study sought to determine whether personal stress is a more significant predictor of burnout, job satisfaction and general health than work stress.

  17. Salubrious effects of oxytocin on social stress-induced deficits

    Science.gov (United States)

    Smith, Adam S.; Wang, Zuoxin

    2012-01-01

    Social relationships are a fundamental aspect of life, affecting social, psychological, physiological, and behavioral functions. While social interactions can attenuate stress and promote health, disruption, confrontations, isolation, or neglect in the social environment can each be major stressors. Social stress can impair the basal function and stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis, impairing function of multiple biological systems and posing a risk to mental and physical health. In contrast, social support can ameliorate stress-induced physiological and immunological deficits, reducing the risk of subsequent psychological distress and improving an individual's overall well-being. For better clinical treatment of these physiological and mental pathologies, it is necessary to understand the regulatory mechanisms of stress-induced pathologies as well as determine the underlying biological mechanisms that regulate social buffering of the stress system. A number of ethologically relevant animal models of social stress and species that form strong adult social bonds have been utilized to study the etiology, treatment, and prevention of stress-related disorders. While undoubtedly a number of biological pathways contribute to the social buffering of the stress response, the convergence of evidence denotes the regulatory effects of oxytocin in facilitating social bond-promoting behaviors and their effect on the stress response. Thus, oxytocin may be perceived as a common regulatory element of the social environment, stress response, and stress-induced risks on mental and physical health. PMID:22178036

  18. Stress associated with group living in a long-lived bird

    OpenAIRE

    Selva, Nuria; Cortés-Avizanda, Ainara; Lemus, Jesús A.; Blanco, Guillermo; Mueller, Thomas; Heinrich, Bernd; Donázar, José A.

    2011-01-01

    Many long-lived avian species adopt life strategies that involve a gregarious way of life at juvenile and sub-adult stages and territoriality during adulthood. However, the potential associated costs of these life styles, such as stress, are poorly understood. We examined the effects of group living, sex and parasite load on the baseline concentration of faecal stress hormone (corticosterone) metabolites in a wild population of common ravens (Corvus corax). Corticosterone concentrations were ...

  19. Motional Effect on Wall Shear Stresses

    DEFF Research Database (Denmark)

    Kock, Samuel Alberg; Torben Fründ, Ernst; Yong Kim, Won

    Atherosclerosis is the leading cause of death and severe disability. Wall Shear Stress (WSS), the stress exerted on vessel walls by the flowing blood is a key factor in the development of atherosclerosis. Computational Fluid Dynamics (CFD) is widely used for WSS estimations. Most CFD simulations...... are based on static models to ease computational burden leading to inaccurate estimations. The aim of this work was to estimate the effect of vessel wall deformations (expansion and bending) on WSS levels....

  20. Effect of Salinity Stress and Foliar Application of Methyl Jasmonate on Photosynthetic Rate, Stomatal Conductance, Water Use Efficiency and Yield of German Chamomile

    Directory of Open Access Journals (Sweden)

    fatemeh Salimi

    2014-09-01

    Full Text Available Jasmonate is new plant growth regulator that plays an essential role at increasing plants resistance to the environmental stresses like salinity stress. Hence, in this research the effect of foliar application of methyl jasmonate on some physiological indices and yield of German chamomile under salinity conditions was studied. A factorial experiment was laid out based on randomized complete block design (RCBD with three replications in the greenhouse condition. Foliar application of methyl jasmonate was five levels (MJ1; 0, MJ2; 75, MJ3; 150, MJ4; 225 and MJ5; 300 μM and salinity stress was four levels (S1; 2, S2; 6, S3; 10, S4; 14 dS m-1. The effect of methyl jasmonate, salinity condition treatments and their interaction was significant for traits of photosynthesis rate, stomata conductance, transpiration rate, carboxylation efficiency, intercellular CO2 concentration and yield of flower. The highest values of photosynthetic rate, stomata conductance, transpiration rate, carboxylation efficiency and yield of flower (3.76 g pot-1 and the lowest intercellular CO2 concentration were achieved at MJ×S treatment. Maximum value of photosynthetic water use efficiency was revealed at MJ5×S2 treatment. With decreasing stomata conductance, photosynthetic water use efficiency and intercellular CO2 concentration were increased. In general, it seems that application of methyl jasmonate by lower dose (MJ2 under salinity conditions especially mild salinity stress (S2 can improve physiological indices and yield of chamomile.

  1. Effects of PEG-induced osmotic stress on growth and dhurrin levels of forage sorghum

    DEFF Research Database (Denmark)

    O'Donnell, Natalie H.; Møller, Birger Lindberg; Neale, Alan D.

    2013-01-01

    Sorghum (Sorghum bicolor L. Moench) is a valuable forage crop in regions with low soil moisture. Sorghum may accumulate high concentrations of the cyanogenic glucoside dhurrin when drought stressed resulting in possible cyanide (HCN) intoxication of grazing animals. In addition, high concentratio...... of plant growth and root activity, increasing the rate of nitrate uptake. Data presented in this article support a role for cyanogenic glucosides in mitigating oxidative stress....... of nitrate, also potentially toxic to ruminants, may accumulate during or shortly after periods of drought. Little is known about the degree and duration of drought-stress required to induce dhurrin accumulation, or how changes in dhurrin concentration are influenced by plant size or nitrate metabolism....... Given that finely regulating soil moisture under controlled conditions is notoriously difficult, we exposed sorghum plants to varying degrees of osmotic stress by growing them for different lengths of time in hydroponic solutions containing polyethylene glycol (PEG). Plants grown in medium containing 20...

  2. Infusion of hypertonic saline before elective hysterectomy: effects on cytokines and stress hormones

    DEFF Research Database (Denmark)

    Kølsen-Petersen, Jens Aage; Bendtzen, Klaus; Tønnesen, Else Kirstine

    2008-01-01

    with the other groups (Peffect on the postoperative concentration of selected plasma cytokines and the hormonal stress......BACKGROUND: Infusion of hypertonic saline provides early haemodynamic benefits and may affect the immune system. It is unknown if infusion of hypertonic saline affects plasma cytokines and stress hormones after surgery. METHODS: Sixty-two women undergoing abdominal hysterectomy were randomized...

  3. Tributyltin-induced endoplasmic reticulum stress and its Ca2+-mediated mechanism

    International Nuclear Information System (INIS)

    Isomura, Midori; Kotake, Yaichiro; Masuda, Kyoichi; Miyara, Masatsugu; Okuda, Katsuhiro; Samizo, Shigeyoshi; Sanoh, Seigo; Hosoi, Toru; Ozawa, Koichiro; Ohta, Shigeru

    2013-01-01

    Organotin compounds, especially tributyltin chloride (TBT), have been widely used in antifouling paints for marine vessels, but exhibit various toxicities in mammals. The endoplasmic reticulum (ER) is a multifunctional organelle that controls post-translational modification and intracellular Ca 2+ signaling. When the capacity of the quality control system of ER is exceeded under stress including ER Ca 2+ homeostasis disruption, ER functions are impaired and unfolded proteins are accumulated in ER lumen, which is called ER stress. Here, we examined whether TBT causes ER stress in human neuroblastoma SH-SY5Y cells. We found that 700 nM TBT induced ER stress markers such as CHOP, GRP78, spliced XBP1 mRNA and phosphorylated eIF2α. TBT also decreased the cell viability both concentration- and time-dependently. Dibutyltin and monobutyltin did not induce ER stress markers. We hypothesized that TBT induces ER stress via Ca 2+ depletion, and to test this idea, we examined the effect of TBT on intracellular Ca 2+ concentration using fura-2 AM, a Ca 2+ fluorescent probe. TBT increased intracellular Ca 2+ concentration in a TBT-concentration-dependent manner, and Ca 2+ increase in 700 nM TBT was mainly blocked by 50 μM dantrolene, a ryanodine receptor antagonist (about 70% inhibition). Dantrolene also partially but significantly inhibited TBT-induced GRP78 expression and cell death. These results suggest that TBT increases intracellular Ca 2+ concentration by releasing Ca 2+ from ER, thereby causing ER stress. - Highlights: • We established that tributyltin induces endoplasmic reticulum (ER) stress. • Tributyltin induces ER stress markers in a concentration-dependent manner. • Tributyltin increases Ca 2+ release from ER, thereby causing ER stress. • Dibutyltin and monobutyltin did not increase GRP78 or intracellular Ca 2+

  4. Effects of chronic stress and interleukin-10 gene polymorphisms on antibody response to tetanus vaccine in family caregivers of patients with Alzheimer's disease.

    Science.gov (United States)

    Li, Jian; Cowden, Linda G; King, Janice D; Briles, David A; Schroeder, Harry W; Stevens, Alan B; Perry, Rodney T; Chen, Zuomin; Simmons, Micah S; Wiener, Howard W; Tiwari, Hemant K; Harrell, Lindy E; Go, Rodney C P

    2007-01-01

    To assess the effects of psychological stress on the antibody response to tetanus vaccine adjusting for cytokine gene polymorphisms and other nongenetic factors in caregivers of patients with Alzheimer's disease (AD). A family-based follow-up study was conducted in 119 spouses and offspring of community-dwelling patients with AD. Psychological stress was measured by the Perceived Stress Scale (PSS) and the Center for Epidemiologic Studies Depression (CES-D) scale at baseline and 1 month after the vaccination. Nutritional status, health behaviors, comorbidity, and stress-buffering factors were assessed by self-administered questionnaires, 10 single nucleotide polymorphisms (SNP) from six selected cytokines genotyped, and anti-tetanus toxoid immunoglobulin G (IgG) concentrations tested using enzyme-linked immunosorbent assays. The effects of stress and other potential confounders were assessed by mixed models that account for familial correlations. The baseline PSS score, the baseline CES-D score, the interleukin-10-1082 A>G SNP GG genotype, and the baseline anti-tetanus IgG were inversely associated with antibody fold increase. Both psychological stress and cytokine gene polymorphisms affected antibody fold increase. The study provided additional support for the detrimental effects of psychological stress on the antibody response to tetanus vaccine.

  5. Effect of different types of prosthetic platforms on stress-distribution in dental implant-supported prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Minatel, Lurian [Pró-Reitoria de Pesquisa e Pós-graduação (PRPPG), Universidade do Sagrado Coração, USC, 10–50 Irmã Armindal, Jardim Brasil, Bauru, 17011–160, SP (Brazil); Verri, Fellippo Ramos [Department of Dental Materials and Prosthodontics, Araçatuba Dental School, UNESP - Univ Estadual Paulista, 1193 José Bonifácio Street, Vila Mendonça, Araçatuba 16015–050 (Brazil); Kudo, Guilherme Abu Halawa [Pró-Reitoria de Pesquisa e Pós-graduação (PRPPG), Universidade do Sagrado Coração, USC, 10–50 Irmã Armindal, Jardim Brasil, Bauru, 17011–160, SP (Brazil); Faria Almeida, Daniel Augusto de; Souza Batista, Victor Eduardo de; Aparecido Araujo Lemos, Cleidiel; Piza Pellizzer, Eduardo [Department of Dental Materials and Prosthodontics, Araçatuba Dental School, UNESP - Univ Estadual Paulista, 1193 José Bonifácio Street, Vila Mendonça, Araçatuba 16015–050 (Brazil); and others

    2017-02-01

    A biomechanical analysis of different types of implant connections is relevant to clinical practice because it may impact the longevity of the rehabilitation treatment. Therefore, the objective of this study is to evaluate the Morse taper connections and the stress distribution of structures associated with the platform switching (PSW) concept. It will do this by obtaining data on the biomechanical behavior of the main structure in relation to the dental implant using the 3-dimensional finite element methodology. Four models were simulated (with each containing a single prosthesis over the implant) in the molar region, with the following specifications: M1 and M2 is an external hexagonal implant on a regular platform; M3 is an external hexagonal implant using PSW concept; and M4 is a Morse taper implant. The modeling process involved the use of images from InVesalius CT (computed tomography) processing software, which were refined using Rhinoceros 4.0 and SolidWorks 2011 CAD software. The models were then exported into the finite element program (FEMAP 11.0) to configure the meshes. The models were processed using NeiNastram software. The main results are that M1 (regular diameter 4 mm) had the highest stress concentration area and highest microstrain concentration for bone tissue, dental implants, and the retaining screw (P < 0.05). Using the PSW concept increases the area of the stress concentrations in the retaining screw (P < 0.05) more than in the regular platform implant. It was concluded that the increase in diameter is beneficial for stress distribution and that the PSW concept had higher stress concentrations in the retaining screw and the crown compared to the regular platform implant. - Highlights: • The external hexagon implants was unfavorable biomechanical. • The Morse taper implant presented the best biomechanical result. • Platform switching concept increased stress in screw-retained prostheses.

  6. Effect of different types of prosthetic platforms on stress-distribution in dental implant-supported prostheses

    International Nuclear Information System (INIS)

    Minatel, Lurian; Verri, Fellippo Ramos; Kudo, Guilherme Abu Halawa; Faria Almeida, Daniel Augusto de; Souza Batista, Victor Eduardo de; Aparecido Araujo Lemos, Cleidiel; Piza Pellizzer, Eduardo

    2017-01-01

    A biomechanical analysis of different types of implant connections is relevant to clinical practice because it may impact the longevity of the rehabilitation treatment. Therefore, the objective of this study is to evaluate the Morse taper connections and the stress distribution of structures associated with the platform switching (PSW) concept. It will do this by obtaining data on the biomechanical behavior of the main structure in relation to the dental implant using the 3-dimensional finite element methodology. Four models were simulated (with each containing a single prosthesis over the implant) in the molar region, with the following specifications: M1 and M2 is an external hexagonal implant on a regular platform; M3 is an external hexagonal implant using PSW concept; and M4 is a Morse taper implant. The modeling process involved the use of images from InVesalius CT (computed tomography) processing software, which were refined using Rhinoceros 4.0 and SolidWorks 2011 CAD software. The models were then exported into the finite element program (FEMAP 11.0) to configure the meshes. The models were processed using NeiNastram software. The main results are that M1 (regular diameter 4 mm) had the highest stress concentration area and highest microstrain concentration for bone tissue, dental implants, and the retaining screw (P < 0.05). Using the PSW concept increases the area of the stress concentrations in the retaining screw (P < 0.05) more than in the regular platform implant. It was concluded that the increase in diameter is beneficial for stress distribution and that the PSW concept had higher stress concentrations in the retaining screw and the crown compared to the regular platform implant. - Highlights: • The external hexagon implants was unfavorable biomechanical. • The Morse taper implant presented the best biomechanical result. • Platform switching concept increased stress in screw-retained prostheses.

  7. A pilot study: Horticulture-related activities significantly reduce stress levels and salivary cortisol concentration of maladjusted elementary school children.

    Science.gov (United States)

    Lee, Min Jung; Oh, Wook; Jang, Ja Soon; Lee, Ju Young

    2018-04-01

    The effects of three horticulture-related activities (HRAs), including floral arranging, planting, and flower pressing were compared to see if they influenced changes on a stress scale and on salivary cortisol concentrations (SCC) in maladjusted elementary school children. Twenty maladjusted elementary school children were randomly assigned either to an experimental or control group. The control group carried out individual favorite indoor activities under the supervision of a teacher. Simultaneously, the ten children in the experimental group participated in a HRA program consisting of flower arrangement (FA), planting (P), and flower pressing (PF) activities, in which the other ten children in the control group did not take part. During nine sessions, the activities were completed as follows: FA-FA-FA, P-P-P, and PF-PF-PF; each session lasted 40 min and took place once a week. For the quantitative analysis of salivary cortisol, saliva was collected from the experimental group one week before the HRAs and immediately after the activities for 9 consecutive weeks at the same time each session. In the experimental group, stress scores of interpersonal relationship, school life, personal problems, and home life decreased after the HRAs by 1.3, 1.8, 4.2, and 1.3 points, respectively. In particular, the stress score of school life was significantly reduced (P < 0.01). In addition, from the investigation of the SCCs for the children before and after repeating HRAs three times, it was found that flower arrangement, planting, and flower pressing activities reduced the SCCs by ≥37% compared to the SCCs prior to taking part in the HRAs. These results indicate that HRAs are associated with a reduction in the stress levels of maladjusted elementary school children. Copyright © 2018. Published by Elsevier Ltd.

  8. Effect of cadmium exposure on hepatopancreas and gills of the estuary mud crab (Scylla paramamosain): Histopathological changes and expression characterization of stress response genes.

    Science.gov (United States)

    Zhu, Qi-Hui; Zhou, Zhong-Kai; Tu, Dan-Dan; Zhou, Yi-Lian; Wang, Cong; Liu, Ze-Peng; Gu, Wen-Bin; Chen, Yu-Yin; Shu, Miao-An

    2018-02-01

    Cadmium (Cd) is a heavy metal that accumulates easily in organisms and causes several detrimental effects, including tissue damage. Cd contamination from anthropogenic terrestrial sources flows into rivers, and through estuaries to the ocean. To evaluate the toxic effects of Cd on estuary crustaceans, we exposed the mud crab Scylla paramamosain to various Cd concentrations (0, 10.0, 20.0, and 40.0mg/L) for 24h. We also exposed mud crabs to a fixed Cd concentration (20.0mg/L) for various periods of time (0, 6, 12, 24, 48, and 72h). We observed that after exposure to Cd, the surfaces of the gill lamellae were wrinkled, and the morphologies of the nuclei and mitochondria in the hepatopancreas were altered. We analyzed the expression profiles of 36 stress-related genes after Cd exposure, including those encoding metallothioneins, heat shock proteins, apoptosis-related proteins, and antioxidant proteins, with quantitative reverse transcription PCR. We found that exposure to Cd altered gene expression, and that some genes might be suitable bioindicators of Cd stress. Gene expression profiles were organ-, duration-, and concentration-dependent, suggesting that stress-response genes might be involved in an innate defense system for handling heavy metal exposure. To the best of our knowledge, this study is the first one of histopathology and stress-response gene expression pattern of Scylla paramamosain after Cd exposure. Our work could increase our understanding of the effect of environmental toxins on estuary crustaceans. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Effect of Biochar on Relieving Cadmium Stress and Reducing Accumulation in Super japonica Rice

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhen-yu; MENG Jun; DANG Shu; CHEN Wen-fu

    2014-01-01

    It is of great importance to solve the threats induced by cadmium pollution on crops. This paper examined the effect of biochar on cadmium accumulation in japonica rice and revealed the mechanism underlying the response of protective enzyme system to cadmium stress. Biochar derived from rice straw was applied at two application rates under three cadmium concentrations. Shennong 265, super japonica rice variety, was selected as the test crop. The results indicated that cadmium content in above-ground biomass of rice increased with increasing soil cadmium concentrations, but the biochar application could suppress the accumulation of cadmium to some extent. Under high concentrations of cadmium, content of free proline and MDA (malondialdehyde) were high, so did the SOD (superoxide dismutase), POD (peroxidase) and CAT (catalase) activity in the lfag leaf of rice. However, the protective enzyme activities remained at low level when biochar was added.

  10. Effects of Kombucha on oxidative stress induced nephrotoxicity in rats.

    Science.gov (United States)

    Gharib, Ola Ali

    2009-11-27

    Trichloroethylene (TCE) may induce oxidative stress which generates free radicals and alters antioxidants or oxygen-free radical scavenging enzymes. Twenty male albino rats were divided into four groups: (1) the control group treated with vehicle, (2) Kombucha (KT)-treated group, (3) TCE-treated group and (4) KT/TCE-treated group. Kidney lipid peroxidation, glutathione content, nitric oxide (NO) and total blood free radical concentrations were evaluated. Serum urea, creatinine level, gamma-glutamyl transferase (GGT) and lactate dehydrogenase (LDH) activities were also measured. TCE administration increased the malondiahyde (MDA) and NO contents in kidney, urea and creatinine concentrations in serum, total free radical level in blood and GGT and LDH activities in serum, whereas it decreased the glutathione (GSH) level in kidney homogenate. KT administration significantly improved lipid peroxidation and oxidative stress induced by TCE. The present study indicates that Kombucha may repair damage caused by environmental pollutants such as TCE and may be beneficial to patient suffering from renal impairment.

  11. Effects of stress and MDMA on hippocampal gene expression.

    Science.gov (United States)

    Weber, Georg F; Johnson, Bethann N; Yamamoto, Bryan K; Gudelsky, Gary A

    2014-01-01

    MDMA (3,4-methylenedioxymethamphetamine) is a substituted amphetamine and popular drug of abuse. Its mood-enhancing short-term effects may prompt its consumption under stress. Clinical studies indicate that MDMA treatment may mitigate the symptoms of stress disorders such as posttraumatic stress syndrome (PTSD). On the other hand, repeated administration of MDMA results in persistent deficits in markers of serotonergic (5-HT) nerve terminals that have been viewed as indicative of 5-HT neurotoxicity. Exposure to chronic stress has been shown to augment MDMA-induced 5-HT neurotoxicity. Here, we examine the transcriptional responses in the hippocampus to MDMA treatment of control rats and rats exposed to chronic stress. MDMA altered the expression of genes that regulate unfolded protein binding, protein folding, calmodulin-dependent protein kinase activity, and neuropeptide signaling. In stressed rats, the gene expression profile in response to MDMA was altered to affect sensory processing and responses to tissue damage in nerve sheaths. Subsequent treatment with MDMA also markedly altered the genetic responses to stress such that the stress-induced downregulation of genes related to the circadian rhythm was reversed. The data support the view that MDMA-induced transcriptional responses accompany the persistent effects of this drug on neuronal structure/function. In addition, MDMA treatment alters the stress-induced transcriptional signature.

  12. Post-traumatic stress disorder in Polish stroke patients who survived Nazi concentration camps.

    Science.gov (United States)

    Pachalska, Maria; Grochmal-Bach, Bozena; MacQueen, Bruce Duncan; Frańczuk, Bogusław

    2006-04-01

    Many persons who survived Nazi concentration camps are now in advanced age, so that rehabilitation centers in Poland are seeing increasing numbers of such patients, especially after strokes. In many cases, the process of rehabilitation is severely hampered by Post-Traumatic Stress Disorder (PTSD), while the neuropsychological consequences of the stroke itself often evoke traumatic memories and simultaneously disorganize or destroy the patient's previous coping mechanisms. The present study describes the program developed by the authors for concentration camp survivors in post-stroke rehabilitation, including the use of art therapy and specially prepared films to help the patients cope with PTSD. The experimental group (KL) consisted of 8 such patients (4 men, 4 women, average age 79.1+/-4.28) with mild post-stroke aphasia who went through the PTSD program, while the comparison group (C) included 8 post-stroke patients, matched for age and gender, who were not concentration camp survivors and showed no premorbid symptoms of PTSD. All subjects were tested at baseline and again 3 months later, using structured interview and observation, self-rating scales for three basic negative emotions (anger, anxiety and sadness) and the Frustration and Aggression Test for the Disabled. The results showed significant differences between the groups at baseline, while at follow-up the differences between groups had changed in both extent and distribution. Qualitative analysis of the results allows for some important observations about the etiology and course of PTSD in these persons.

  13. Effect of mixed adhesive joints and tapered plate on stresses in retrofitted beams bonded with a fiber-reinforced polymer plate

    International Nuclear Information System (INIS)

    Bouchikhi, A.S.; Megueni, A.; Gouasmi, S.; Boukoulda, F.B.

    2013-01-01

    Highlights: • Interface stress distribution in beams reinforced composites jointed by homogeneous adhesive. • The reduction of stresses interfaces by using the tapered plate at edges. • The reduction of stresses interfaces by using the bi-adhesive. • The reduction of stresses interfaces by combining between the tapered plate and the bi-adhesive. - Abstract: This paper focuses on the reduction of interfacial stresses when using bonded laminates in strengthening existing structures. The presence of high interfacial stresses that develop near the end of composite known as edge effect may compromise the résistance to failure of strengthened structure. It is known that the decrease of plate thickness and fitness of adhesive (Young modulus) reduces the stress concentration at plate ends. Another way to tackle the problem is proper design of the plate end shape (tapered plate) and using mixed adhesive joints (MAJs) between the adherents. In this paper, a comprehensive finite element (FE) study has been conducted to investigate the effect of mixed adhesive joints (MAJs) and tapering plate on the interfacial stress distribution in the adhesive layer in retrofitted steel beam with fiber reinforced polymer (FRP) plate, This results indicate that using the correct combination of tapering plate at the end and mixed adhesive joints can reduce the magnitude of the interfacial stresses significantly

  14. Differences in Susceptibility to Heat Stress along the Chicken Intestine and the Protective Effects of Galacto-Oligosaccharides.

    Directory of Open Access Journals (Sweden)

    Soheil Varasteh

    Full Text Available High ambient temperatures negatively affect the human well-being as well as animal welfare and production. The gastrointestinal tract is predominantly responsive to heat stress. The currently available information about the multifaceted response to heat stress within different parts of the intestine is limited, especially in avian species. Hence, this study aims to evaluate the heat stress-induced sequence of events in the intestines of chickens. Furthermore, the gut health-promoting effect of dietary galacto-oligosaccharides (GOS was investigated in these heat stress-exposed chickens. Chickens were fed a control diet or diet supplemented with 1% or 2.5% GOS (6 days prior to and during a temperature challenge for 5 days (38-39°C, 8h per day. The parameters measured in different parts of the intestines included the genes (qPCR HSF1, HSF3, HSP70, HSP90, E-cadherin, claudin-1, claudin-5, ZO-1, occludin, TLR-2, TLR-4, IL-6, IL-8, HO-1, HIF-1α and their associated proteins HSP70, HSP90 and pan-cadherin (western blots. In addition, IL-6 and IL-8 plasma concentrations were measured by ELISA. In the jejunum, HSF3, HSP70, HSP90, E-cadherin, claudin-5, ZO-1, TLR-4, IL-6 and IL-8 mRNA expression and HSP70 protein expression were increased after heat stress exposure and a more pronounced increase in gene expression was observed in ileum after heat stress exposure, and in addition HSF1, claudin-1 and HIF-1α mRNA levels were upregulated. Furthermore, the IL-8 plasma levels were decreased in chickens exposed to heat stress. Interestingly, the heat stress-related effects in the jejunum were prevented in chickens fed a GOS diet, while dietary GOS did not alter these effects in ileum. In conclusion, our results demonstrate the differences in susceptibility to heat stress along the intestine, where the most obvious modification in gene expression is observed in ileum, while dietary GOS only prevent the heat stress-related changes in jejunum.

  15. The effect of fiber microstructure on evolution of residual stresses in silicon carbide/titanium aluminide composites

    Science.gov (United States)

    Pindera, Marek-Jerzy; Freed, Alan D.

    1992-01-01

    This paper examines the effect of the morphology of the SCS6 silicon carbide fiber on the evolution of residual stresses in SiC/Ti composites. A micromechanics model based on the concentric cylinder concept is presented which is used to calculate residual stresses in a SiC/Ti composite during axisymmetric cooling by a spatially uniform temperature change. The silicon carbide fiber is modeled as a layered material with five distinct transversely isotropic and orthotropic, elastic layers, whereas the titanium matrix is taken to be isotropic, with temperature-dependent elastoplastic properties. The results arc compared with those obtained based on the assumption that the silicon carbide fiber is isotropic and homogeneous.

  16. Loneliness and sleep quality: dyadic effects and stress effects.

    Science.gov (United States)

    Segrin, Chris; Burke, Tricia J

    2015-01-01

    The aims of this investigation are to determine whether loneliness is associated with a person's own sleep quality and sleep quality of their partner, and to test stress as a potential mediator. Participants were 255 couples in married (75%) or cohabiting relationships who completed self-report measures of loneliness, sleep quality, stress, and depression. Results of Actor-Partner Interdependence analyses replicated findings in the literature showing an association between loneliness and poor sleep quality. The more lonely a male participant was, the lower his partner's sleep quality. In addition, the more lonely participants were, the higher they rated their partner's sleep disturbance. There were significant indirect effects of loneliness on poor sleep quality through increased stress, even after controlling for depression.

  17. Investigation into ammonia stress on Cyperus alternifolius and its impact on nutrient removal in microcosm experiments.

    Science.gov (United States)

    Tao, Wendong; Han, Jianqiu; Li, Hanyan

    2015-11-01

    Ammonia stress on plants has been investigated at discrete ammonia concentrations in constructed wetlands. This study introduced a Gaussian model to simulate the kinetics of ammonia stress and investigated reversible and irreversible ammonia stress on Cyperus alternifolius in wetland-like microcosms. Ammonia stress on plant weight increase and oxygen release potential started at weekly ammonia concentrations of 27 and 28 mg N/L, reached 50% inhibition at 178 and 158 mg N/L, and resulted in lethal effects at 311 and 303 mg N/L, respectively. The stress of one-time ammonia concentrations up to 400 mg N/L could be reversible. Ammonia concentrations constantly above 219 mg N/L exerted irreversible stress. In the microcosms with ammonia concentrations above the 50% inhibition levels, plants played a minor role in nitrogen removal. Nitrogen removal performance was not affected considerably by ammonia stress. Orthophosphate removal was suppressed by ammonia stress due to less plant uptake. Design and operation of constructed wetlands should consider wastewater ammonia concentration so that the integrity of constructed wetland ecosystems can be maintained. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Effects of location, thermal stress and residual stress on corner cracks in nozzles with cladding

    International Nuclear Information System (INIS)

    McLean, J.L.; Cohen, L.M.; Besuner, P.M.

    1979-01-01

    The stress intensity factors (K 1 ) for corner cracks in a boiling water reactor feedwater nozzle with stainless steel cladding are obtained for loading by internal pressure and a fluid quench in the nozzle. Conditions both with and without residual stress in the component are considered. The residual stress is simulated by means of a reference temperature change. The stress distribution for the uncracked structure is obtained from a three-dimensional finite element model. A three-dimensional influence function (IF) method, in conjunction with the boundary-integral equation method for structural analysis, is employed to compute K 1 values from the uncracked stress distribution. For each type of loading K 1 values are given for cracks at 15 nozzle locations and for 6 crack depths. Reasonable agreement is noted between calculated and previously published pressure-induced K 1 values. Comparisons are made to determine the effect on K 1 of crack location, thermal stress and residual stress, as compared with pressure stress. For the thermal transient it is shown that K 1 for small crack depths is maximised early in the transient, while K 1 for large cracks is maximised later under steady state conditions. Computation should, therefore, be made for several transient time points and the maximum K 1 for a given crack depth should be used for design analysis. It is concluded that the effects on K 1 of location, thermal stresses and residual stresses are significant and generally too complex to evaluate without advanced numerical procedures. The utilised combination of finite element analysis of the uncracked structure and three-dimensional influence function analysis of the cracked structure is demonstrated and endorsed. (author)

  19. Sources and effects of work-related stress among employees in foreign-owned manufacturing companies in Ogun state, Nigeria

    Directory of Open Access Journals (Sweden)

    Ajibade David

    2016-12-01

    Full Text Available This study investigates the sources and effects of work-related stress among employees in foreign owned manufacturing companies in Ogun State, Nigeria. The study used cross sectional descriptive design and a total of three hundred and two (302 respondents were selected using stratified random sampling technique from five randomly selected foreign-owned manufacturing companies. Data were collected using questionnaire and statistically analysed using frequencies, percentages and weighted means. The study reveals factors such as unfavourable physical working conditions, job insecurity, poor career development, and long working hours fostering stress on employees in the sampled companies. The study further reveals that respondents suffered consequences such as restlessness, anxiety and nervous indigestion, headache, neck ache, and inability to concentrate. This study however has implication for management of foreign-owned manufacturing organization. Based on this, appropriate recommendations were made application of which will help to ensure enabling workplace environment and thus reduce the effects of stress on employees.

  20. Low concentrations of metal mixture exposures have adverse effects on selected biomarkers of Xenopus laevis tadpoles

    Energy Technology Data Exchange (ETDEWEB)

    Yologlu, Ertan, E-mail: ertanyologlu82@gmail.com [Adiyaman University, Faculty of Education, Department of Science Education, 02040 Adiyaman (Turkey); Ozmen, Murat [Inonu University, Laboratory of Environmental Toxicology, Department of Biology, Faculty of Arts & Science, 44280 Malatya (Turkey)

    2015-11-15

    Highlights: • Selected metal mixtures were evaluated for toxicity of safety limit concentrations. • Xenopus laevis tadpoles were used as model test organism. • Combinations of LC{sub 50} and LC{sub 50}/2 caused 100% lethality for some metals. • Metals did not change metallothionein levels in low concentrations. • Selected enzyme activities showed induction after low concentration exposures. - Abstract: Polluted ecosystems may contain mixtures of metals, such that the combinations of metals, even in low concentrations, may cause adverse effects. In the present study, we focused on toxic effects of mixtures of selected metals, the LC{sub 50} values, and also their safety limit in aquatic systems imposed by the European legislation using a model organism. Xenopus laevis tadpoles were used as test organisms. They were exposed to metals or their combinations due to 96-h LC{sub 50} values. Glutathione S-transferase (GST), glutathione reductase (GR), acetylcholinesterase (AChE), carboxylesterase (CaE), glutathione peroxidase (GPx), and catalase (CAT) levels were evaluated. Metallothionein concentrations were also determined. The LC{sub 50}s for Cd, Pb, and Cu were calculated as 5.81 mg AI/L, 123.05 mg AI/L, and 0.85 mg AI/L, respectively. Low lethality ratios were observed with unary exposure of each metal in lower concentrations. Double or triple combinations of LC{sub 50} and LC{sub 50}/2 concentrations caused 100% lethality with Cd + Cu and Pb + Cd + Cu mixtures, while the Pb + Cu mixture also caused high lethal ratios. The selected enzyme activities were significantly affected by metals or mixtures, and dose-related effects were determined. The metallothionein levels generally increased as related to concentration in unary metals and mixtures. Acceptable limit values of unary metals and mixtures did not significantly change metallothionein levels. The results suggest that oxidative stress-related mechanisms are involved in the toxicity induced by selected

  1. Effectiveness of a Comprehensive Stress Management Program to Reduce Work-Related Stress in a Medium-Sized Enterprise

    Science.gov (United States)

    2014-01-01

    Objectives To assess the effectiveness of a comprehensive workplace stress management program consisting of participatory action-oriented training (PAOT) and individual management. Methods A comprehensive workplace stress management program was conducted in a medium-sized enterprise. The baseline survey was conducted in September 2011, using the Korean Occupational Stress Scale (KOSS) and Worker’s Stress Response Inventory (WSRI). After implementing both organizational and individual level interventions, the follow up evaluation was conducted in November 2011. Results Most of the workers participated in the organizational level PAOT and made Team-based improvement plans. Based on the stress survey, 24 workers were interviewed by a researcher. After the organizational and individual level interventions, there was a reduction of several adverse psychosocial factors and stress responses. In the case of blue-collar workers, psychosocial factors such as the physical environment, job demands, organizational system, lack of rewards, and occupational climate were significantly improved; in the case of white-collar workers, the occupational climate was improved. Conclusions In light of these results, we concluded that the comprehensive stress management program was effective in reducing work-related stress in a short-term period. A persistent long-term follow up is necessary to determine whether the observed effects are maintained over time. Both team-based improvement activities and individual interviews have to be sustainable and complementary to each other under the long-term plan. PMID:24524591

  2. Effectiveness of a comprehensive stress management program to reduce work-related stress in a medium-sized enterprise.

    Science.gov (United States)

    Kim, Shin-Ae; Suh, Chunhui; Park, Mi-Hee; Kim, Kunhyung; Lee, Chae-Kwan; Son, Byung-Chul; Kim, Jeong-Ho; Lee, Jong-Tae; Woo, Kuck-Hyun; Kang, Kabsoon; Jung, Hyunjin

    2014-01-01

    To assess the effectiveness of a comprehensive workplace stress management program consisting of participatory action-oriented training (PAOT) and individual management. A comprehensive workplace stress management program was conducted in a medium-sized enterprise. The baseline survey was conducted in September 2011, using the Korean Occupational Stress Scale (KOSS) and Worker's Stress Response Inventory (WSRI). After implementing both organizational and individual level interventions, the follow up evaluation was conducted in November 2011. Most of the workers participated in the organizational level PAOT and made Team-based improvement plans. Based on the stress survey, 24 workers were interviewed by a researcher. After the organizational and individual level interventions, there was a reduction of several adverse psychosocial factors and stress responses. In the case of blue-collar workers, psychosocial factors such as the physical environment, job demands, organizational system, lack of rewards, and occupational climate were significantly improved; in the case of white-collar workers, the occupational climate was improved. In light of these results, we concluded that the comprehensive stress management program was effective in reducing work-related stress in a short-term period. A persistent long-term follow up is necessary to determine whether the observed effects are maintained over time. Both team-based improvement activities and individual interviews have to be sustainable and complementary to each other under the long-term plan.

  3. Effective Stress Management: A Model of Emotional Intelligence, Self-Leadership, and Student Stress Coping

    Science.gov (United States)

    Houghton, Jeffery D.; Wu, Jinpei; Godwin, Jeffrey L.; Neck, Christopher P.; Manz, Charles C.

    2012-01-01

    This article develops and presents a model of the relationships among emotional intelligence, self-leadership, and stress coping among management students. In short, the authors' model suggests that effective emotion regulation and self-leadership, as mediated through positive affect and self-efficacy, has the potential to facilitate stress coping…

  4. Hair cortisol concentrations and cortisol stress reactivity predict PTSD symptom increase after trauma exposure during military deployment.

    Science.gov (United States)

    Steudte-Schmiedgen, Susann; Stalder, Tobias; Schönfeld, Sabine; Wittchen, Hans-Ulrich; Trautmann, Sebastian; Alexander, Nina; Miller, Robert; Kirschbaum, Clemens

    2015-09-01

    Previous evidence on endocrine risk markers for posttraumatic stress disorder (PTSD) has been inconclusive. Here, we report results of the first prospective study to investigate whether long-term hair cortisol levels and experimentally-induced cortisol stress reactivity are predictive of the development of PTSD symptomatology in response to trauma during military deployment. Male soldiers were examined before deployment to Afghanistan and at a 12-month post-deployment follow-up using dimensional measures for psychopathological symptoms. The predictive value of baseline (i) hair cortisol concentrations (HCC, N=90) and (ii) salivary cortisol stress reactivity (measured by the Trier Social Stress Test, N=80) for the development of PTSD symptomatology after being exposed to new-onset traumatic events was analyzed. Baseline cortisol activity significantly predicted PTSD symptom change from baseline to follow-up upon trauma exposure. Specifically, our results consistently revealed that lower HCC and lower cortisol stress reactivity were predictive of a greater increase in PTSD symptomatology in soldiers who had experienced new-onset traumatic events (explaining 5% and 10.3% of variance, respectively). Longitudinal analyses revealed an increase in HCC from baseline to follow-up and a trend for a negative relationship between HCC changes and the number of new-onset traumatic events. Additional pre-deployment analyses revealed that trauma history was reflected in lower HCC (at trend level) and that HCC were negatively related to stressful load. Our data indicate that attenuated cortisol secretion is a risk marker for subsequent development of PTSD symptomatology upon trauma exposure. Future studies are needed to confirm our findings in other samples. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Mosquito control pesticides and sea surface temperatures have differential effects on the survival and oxidative stress response of coral larvae.

    Science.gov (United States)

    Ross, Cliff; Olsen, Kevin; Henry, Michael; Pierce, Richard

    2015-04-01

    The declining health of coral reefs is intensifying worldwide at an alarming rate due to the combined effects of land-based sources of pollution and climate change. Despite the persistent use of mosquito control pesticides in populated coastal areas, studies examining the survival and physiological impacts of early life-history stages of non-targeted marine organisms are limited. In order to better understand the combined effects of mosquito pesticides and rising sea surface temperatures, we exposed larvae from the coral Porites astreoides to selected concentrations of two major mosquito pesticide ingredients, naled and permethrin, and seawater elevated +3.5 °C. Following 18-20 h of exposure, larvae exposed to naled concentrations of 2.96 µg L(-1) or greater had significantly reduced survivorship compared to controls. These effects were not detected in the presence of permethrin or elevated temperature. Furthermore, larval settlement, post-settlement survival and zooxanthellae density were not impacted by any treatment. To evaluate the sub-lethal stress response of larvae, several oxidative stress endpoints were utilized. Biomarker responses to pesticide exposure were variable and contingent upon pesticide type as well as the specific biomarker being employed. In some cases, such as with protein carbonylation and catalase gene expression, the effects of naled exposure and temperature were interactive. In other cases pesticide exposure failed to induce any sub-lethal stress response. Overall, these results demonstrate that P. astreoides larvae have a moderate degree of resistance against short-term exposure to ecologically relevant concentrations of pesticides even in the presence of elevated temperature. In addition, this work highlights the importance of considering the complexity and differential responses encountered when examining the impacts of combined stressors that occur on varying spatial scales.

  6. Effect of Fe ion concentration on fatigue life of carbon steel in aqueous CO2 environment

    DEFF Research Database (Denmark)

    Rogowska, Magdalena; Gudme, J.; Rubin, A.

    2016-01-01

    situ measurements of Fe2+ and pH. Characterisation of the corrosion scales and crack formations was performed using microscopic and diffraction techniques. Fatigue results showed two times better fatigue life, at the stress ranges of 250 MPa, for samples tested in solutions containing the concentration...... of Fe2+ marginally above the solubility limit of FeCO3 compared to the samples tested in highly supersaturated solution of Fe2+. Results revealed that the impact of the alternating stresses on the corrosion behaviour of samples reduces with lowering the applied stresses. At the stress range of 100 MPa...

  7. The antiestrogen endoxifen protects rat liver mitochondria from permeability transition pore opening and oxidative stress at concentrations that do not affect the phosphorylation efficiency

    International Nuclear Information System (INIS)

    Ribeiro, Mariana P.C.; Silva, Filomena S.G.; Santos, Armanda E.; Santos, Maria S.; Custódio, José B.A.

    2013-01-01

    Endoxifen (EDX) is a key active metabolite of tamoxifen (TAM) with higher affinity and specificity to estrogen receptors that also inhibits aromatase activity. It is safe and well tolerated by healthy humans, but its use requires toxicological characterization. In this study, the effects of EDX on mitochondria, the primary targets for xenobiotic-induced toxicity, were monitored to clarify its potential side effects. EDX up to 30 nmol/mg protein did not affect the mitochondrial oxidative phosphorylation. At 50 nmol EDX/mg protein, EDX decreased the ADP phosphorylation rate and a partial collapse of mitochondrial membrane potential (Δψ), that parallels a state 4 stimulation, was observed. As the stimulation of state 4 was not inhibited by oligomycin and 50 nmol EDX/mg protein caused a slight decrease in the light scattering of mitochondria, these data suggest that EDX promotes membrane permeabilization to protons, whereas TAM at the same concentration induced mitochondrial membrane disruption. Moreover, EDX at 10 nmol/mg protein prevented and reversed the Ca 2+ -induced depolarization of ΔΨ and the release of mitochondrial Ca 2+ , similarly to cyclosporine A, indicating that EDX did not affect Ca 2+ uptake, but directly interfered with the proteins of the mitochondrial permeability transition (MPT) megacomplex, inhibiting MPT induction. At this concentration, EDX exhibited antioxidant activity that may account for the protective effect against MPT pore opening. In conclusion, EDX within the range of concentrations reached in tissues did not significantly damage the bioenergetic functions of mitochondria, contrarily to the prodrug TAM, and prevented the MPT pore opening and the oxidative stress in mitochondria, supporting that EDX may be a less toxic drug for women with breast carcinoma. - Highlights: ► Mitochondria are important targets of Endoxifen. ► Endoxifen prevents mitochondrial permeability transition. ► Endoxifen prevents oxidative stress in

  8. The antiestrogen endoxifen protects rat liver mitochondria from permeability transition pore opening and oxidative stress at concentrations that do not affect the phosphorylation efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Mariana P.C.; Silva, Filomena S.G.; Santos, Armanda E. [Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra (Portugal); Laboratory of Biochemistry, Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra (Portugal); Santos, Maria S. [Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra (Portugal); Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, 3004-517 Coimbra (Portugal); Custódio, José B.A., E-mail: custodio@ci.uc.pt [Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra (Portugal); Laboratory of Biochemistry, Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra (Portugal)

    2013-02-15

    Endoxifen (EDX) is a key active metabolite of tamoxifen (TAM) with higher affinity and specificity to estrogen receptors that also inhibits aromatase activity. It is safe and well tolerated by healthy humans, but its use requires toxicological characterization. In this study, the effects of EDX on mitochondria, the primary targets for xenobiotic-induced toxicity, were monitored to clarify its potential side effects. EDX up to 30 nmol/mg protein did not affect the mitochondrial oxidative phosphorylation. At 50 nmol EDX/mg protein, EDX decreased the ADP phosphorylation rate and a partial collapse of mitochondrial membrane potential (Δψ), that parallels a state 4 stimulation, was observed. As the stimulation of state 4 was not inhibited by oligomycin and 50 nmol EDX/mg protein caused a slight decrease in the light scattering of mitochondria, these data suggest that EDX promotes membrane permeabilization to protons, whereas TAM at the same concentration induced mitochondrial membrane disruption. Moreover, EDX at 10 nmol/mg protein prevented and reversed the Ca{sup 2+}-induced depolarization of ΔΨ and the release of mitochondrial Ca{sup 2+}, similarly to cyclosporine A, indicating that EDX did not affect Ca{sup 2+} uptake, but directly interfered with the proteins of the mitochondrial permeability transition (MPT) megacomplex, inhibiting MPT induction. At this concentration, EDX exhibited antioxidant activity that may account for the protective effect against MPT pore opening. In conclusion, EDX within the range of concentrations reached in tissues did not significantly damage the bioenergetic functions of mitochondria, contrarily to the prodrug TAM, and prevented the MPT pore opening and the oxidative stress in mitochondria, supporting that EDX may be a less toxic drug for women with breast carcinoma. - Highlights: ► Mitochondria are important targets of Endoxifen. ► Endoxifen prevents mitochondrial permeability transition. ► Endoxifen prevents oxidative

  9. Effects of work stress and home stress on autonomic nervous function in Japanese male workers.

    Science.gov (United States)

    Maeda, Eri; Iwata, Toyoto; Murata, Katsuyuki

    2015-01-01

    Autonomic imbalance is one of the important pathways through which psychological stress contributes to cardiovascular diseases/sudden death. Although previous studies have focused mainly on stress at work (work stress), the association between autonomic function and stress at home (home stress) is still poorly understood. The purpose was to clarify the effect of work/home stress on autonomic function in 1,809 Japanese male workers. We measured corrected QT (QTc) interval and QT index on the electrocardiogram along with blood pressure and heart rate. Participants provided self-reported information about the presence/absence of work/home stress and the possible confounders affecting QT indicators. Home stress was related positively to QT index (p=0.040) after adjusting for the possible confounders, though work stress did not show a significant relation to QTc interval or QT index. The odds ratio of home stress to elevated QT index (≥105) was 2.677 (95% CI, 1.050 to 6.822). Work/home stress showed no significant relation to blood pressure or heart rate. These findings suggest that autonomic imbalance, readily assessed by QT indicators, can be induced by home stress in Japanese workers. Additional research is needed to identify different types of home stress that are strongly associated with autonomic imbalance.

  10. Occupational Stress

    OpenAIRE

    Löblová, Klára

    2011-01-01

    The thesis deals with load, stress and related questions of the working life. Work-related stress brings numerous difficulties not only to affected individuals, but as a result also to organizations. The thesis follows symptoms, impacts, somatic and mental aspects of stress, its types and also types of stressors, which cause this problem. It is concentrated on workload as a specific area of work-related stress, individual resistance to the load, factors of workload and work-related stress and...

  11. Statins Prevent Dextrose-Induced Endoplasmic Reticulum Stress and Oxidative Stress in Endothelial and HepG2 Cells.

    Science.gov (United States)

    Kojanian, Hagop; Szafran-Swietlik, Anna; Onstead-Haas, Luisa M; Haas, Michael J; Mooradian, Arshag D

    Statins have favorable effects on endothelial function partly because of their capacity to reduce oxidative stress. However, antioxidant vitamins, unlike statins, are not as cardioprotective, and this paradox has been explained by failure of vitamin antioxidants to ameliorate endoplasmic reticulum (ER) stress. To determine whether statins prevent dextrose-induced ER stress in addition to their antioxidative effects, human umbilical vein endothelial cells and HepG2 hepatocytes were treated with 27.5 mM dextrose in the presence of simvastatin (lipophilic statin that is a prodrug) and pravastatin (water-soluble active drug), and oxidative stress, ER stress, and cell death were measured. Superoxide generation was measured using 2-methyl-6-(4-methoxyphenyl)-3,7-dihydroimidazo[1,2-A]pyrazin-3-one hydrochloride. ER stress was measured using the placental alkaline phosphatase assay and Western blot of glucose-regulated protein 75, c-jun-N-terminal kinase, phospho-JNK, eukaryotic initiating factor 2α and phospho-eIF2α, and X-box binding protein 1 mRNA splicing. Cell viability was measured by propidium iodide staining. Superoxide anion production, ER stress, and cell death induced by 27.5 mM dextrose were inhibited by therapeutic concentrations of simvastatin and pravastatin. The salutary effects of statins on endothelial cells in reducing both ER stress and oxidative stress observed with pravastatin and the prodrug simvastatin suggest that the effects may be independent of cholesterol-lowering activity.

  12. Effects of salinity and particle concentration on sediment hydrodynamics and critical bed-shear-stress for erosion of fine grained sediments used in wetland restoration projects

    Science.gov (United States)

    Ghose-Hajra, M.; McCorquodale, A.; Mattson, G.; Jerolleman, D.; Filostrat, J.

    2015-03-01

    Sea-level rise, the increasing number and intensity of storms, oil and groundwater extraction, and coastal land subsidence are putting people and property at risk along Louisiana's coast, with major implications for human safety and economic health of coastal areas. A major goal towards re-establishing a healthy and sustainable coastal ecosystem has been to rebuild Louisiana's disappearing wetlands with fine grained sediments that are dredged or diverted from nearby rivers, channels and lakes to build land in open water areas. A thorough geo-hydrodynamic characterization of the deposited sediments is important in the correct design and a more realistic outcome assessment of the long-term performance measures for ongoing coastal restoration projects. This paper evaluates the effects of salinity and solid particle concentration on the re-suspension characteristics of fine-grained dredged sediments obtained from multiple geographic locations along the Gulf coast. The critical bed-shear-stress for erosion has been evaluated as a function of sedimentation time. The sediment hydrodynamic properties obtained from the laboratory testing were used in a numerical coastal sediment distribution model to aid in evaluating sediment diversions from the Mississippi River into Breton Sound and Barataria Bay.

  13. Effects of salinity and particle concentration on sediment hydrodynamics and critical bed-shear-stress for erosion of fine grained sediments used in wetland restoration projects

    Directory of Open Access Journals (Sweden)

    M. Ghose-Hajra

    2015-03-01

    Full Text Available Sea-level rise, the increasing number and intensity of storms, oil and groundwater extraction, and coastal land subsidence are putting people and property at risk along Louisiana’s coast, with major implications for human safety and economic health of coastal areas. A major goal towards re-establishing a healthy and sustainable coastal ecosystem has been to rebuild Louisiana’s disappearing wetlands with fine grained sediments that are dredged or diverted from nearby rivers, channels and lakes to build land in open water areas. A thorough geo-hydrodynamic characterization of the deposited sediments is important in the correct design and a more realistic outcome assessment of the long-term performance measures for ongoing coastal restoration projects. This paper evaluates the effects of salinity and solid particle concentration on the re-suspension characteristics of fine-grained dredged sediments obtained from multiple geographic locations along the Gulf coast. The critical bed-shear-stress for erosion has been evaluated as a function of sedimentation time. The sediment hydrodynamic properties obtained from the laboratory testing were used in a numerical coastal sediment distribution model to aid in evaluating sediment diversions from the Mississippi River into Breton Sound and Barataria Bay.

  14. Effects of dietary combination of chromium and biotin on egg production, serum metabolites, and egg yolk mineral and cholesterol concentrations in heat-distressed laying quails.

    Science.gov (United States)

    Sahin, K; Onderci, M; Sahin, N; Gursu, M F; Vijaya, J; Kucuk, O

    2004-11-01

    Chromium picolinate is used in the poultry diet because of its antistress effects in addition to the fact that the requirement for it is increased during stress. This study was conducted to determine if the negative effects of high ambient temperature (34 degrees C) on egg production, egg quality, antioxidant status, and cholesterol and mineral content of egg yolk could be alleviated by combination of chromium picolinate and biotin (0.6/2.0; Diachrome, as formulated by Nutrition 21 Inc.), in laying Japanese quails (Coturnix coturnix japanica). Quails (n= 240; 50 d old) were divided into 8 groups, 30 birds per group. The quails were fed either a basal diet or the basal diet supplemented with 2, 4, or 8 mg of Diachrome/kg diet. Birds were kept at 22 degrees C and 53% relative humidity (RH). At 14 wk of age, the thermoneutral (TN) group remained in the same temperature as at the beginning of experiment, whereas the heat stress (HS) group was kept in an environment-controlled room (34 degrees C and 41% RH) for 3 wk. Heat exposure decreased performance when the basal diet was fed (p = 0.001). Diachrome supplementation at 4 and 8 mg/kg diet, increased feed intake (p = 0.05), egg production (p = 0.05), feed efficiency (p = 0.01), egg weight (p = 0.05), and Haugh unit (p = 0.01) in quails reared under heat stress conditions. Heat exposure increased concentrations of serum malondialdehyde (MDA) (p = 0.001), glucose, and cholesterol (p = 0.01), which were elevated by supplemental Diachrome (p < or = 0.05). Egg yolk Cr, Zn, and Fe (p = 0.01) concentrations increased linearly, whereas MDA and cholesterol concentrations decreased (p = 0.05) as dietary Diachrome supplementation increased in HS groups. Similar effects of supplementation on serum levels of glucose and cholesterol (p = 0.05) and egg yolk concentrations of cholesterol (p = 0.05) and Cr (p = 0.01) were observed in TN groups. No significant differences in other values were observed in the TN groups. Results of the

  15. Psychological stress on female mice diminishes the developmental potential of oocytes: a study using the predatory stress model.

    Directory of Open Access Journals (Sweden)

    Yu-Xiang Liu

    Full Text Available Although the predatory stress experimental protocol is considered more psychological than the restraint protocol, it has rarely been used to study the effect of psychological stress on reproduction. Few studies exist on the direct effect of psychological stress to a female on developmental competence of her oocytes, and the direct effect of predatory maternal stress on oocytes has not been reported. In this study, a predatory stress system was first established for mice with cats as predators. Beginning 24 h after injection of equine chorionic gonadotropin, female mice were subjected to predatory stress for 24 h. Evaluation of mouse responses showed that the predatory stress system that we established increased anxiety-like behaviors and plasma cortisol concentrations significantly and continuously while not affecting food and water intake of the mice. In vitro experiments showed that whereas oocyte maturation and Sr(2+ activation or fertilization were unaffected by maternal predatory stress, rate of blastocyst formation and number of cells per blastocyst decreased significantly in stressed mice compared to non-stressed controls. In vivo embryo development indicated that both the number of blastocysts recovered per donor mouse and the average number of young per recipient after embryo transfer of blastocysts with similar cell counts were significantly lower in stressed than in unstressed donor mice. It is concluded that the predatory stress system we established was both effective and durative to induce mouse stress responses. Furthermore, predatory stress applied during the oocyte pre-maturation stage significantly impaired oocyte developmental potential while exerting no measurable impact on nuclear maturation, suggesting that cytoplasmic maturation of mouse oocytes was more vulnerable to maternal stress than nuclear maturation.

  16. Effects of Social Defeat Stress on Sleep in Mice

    OpenAIRE

    Henderson, Fiona; Vialou, Vincent; El Mestikawy, Salah; Fabre, Véronique

    2017-01-01

    Stress plays a key role in the development of psychiatric disorders and has a negative impact on sleep integrity. In mice, chronic social defeat stress (CSDS) is an ethologically valid model of stress-related disorders but little is known about its effects on sleep regulation. Here, we investigated the immediate and long-term effects of 10 consecutive days of social defeat (SD) on vigilance states in C57Bl/6J male mice. Social behavior was assessed to identify susceptible mice, i.e., mice tha...

  17. Effect of insulin pump infusion on comprehensive stress state of ...

    African Journals Online (AJOL)

    Effect of insulin pump infusion on comprehensive stress state of patients with diabetic ketoacidosis. ... Relevant diabetes-associated serum indices, oxidative stress and stress hormone levels were compared between the ... from 32 Countries:.

  18. Stress concentration factor and stress intensity factor on hard metals in connection with the wear characteristics

    International Nuclear Information System (INIS)

    Dawihl, W.; Altmeyer, G.

    1977-01-01

    Description of a method to determine stress intensity factors on hard metals by lapping in notches of different diameter. Dependence of the values of the stress intensity factors on the size of the notch base diameter. For tungsten carbide hard metals with 6% Co, determination of a final value of 250 Nmm -3 / 2 . Characterisation of the stress intensity factor governed by the surface roughness which is decisive for the assessment of the wear-resistant behaviour. (orig.) [de

  19. Effect of osmotic stress and post-stress recovery on the content of phenolics and properties of antioxidants in germinating seeds of grapevine Vitis californica

    Directory of Open Access Journals (Sweden)

    Stanisław Weidner

    2011-05-01

    Full Text Available The tested material consisted of grapevine Vitis californica stratified seeds germinated under optimum conditions (+25°C in water, under osmotic stress (-0.2 MPa in PEG solution and submitted to recovery after stress (+25°C in water. The germinating seeds were determined to contain tannins, catechins and the following phenolic acids: gallic, caffeic, p-coumaric and ferulic. The acids occurred in free, ester- and glycoside-bound forms. The dominant form of phenolic acids was the ester-bound fraction. Gallic acid was the most abundant phenolic acid in germinating seeds, while ferulic acid appeared in the smallest amounts. Our analysis of tannins demonstrated that osmotic stress depressed their concentration. Presence of catechin group compounds such as catechin and epicatechin was also determined. In each sample epicatechin was dominant. The total concentration of catechin increased under stress conditions and declined during post-stress recovery. Catechins are a constituent of tannins and their increase under osmotic stress is most probably caused by the breakdown of some tannins in seeds germinating under stress conditions. Samples submitted to osmotic stress were also found to contain less of total phenolic compounds, whereas in samples which underwent post-stress recovery the total level of phenolic compounds increased. Compared to extracts from seeds germinating under optimum conditions, osmotic stress depressed the capacity of extract to scavenge DPPH● (2,2-diphenyl-1-picrylhydrazyl and ABTS●+ – 2,2-Azino-bis (3-etylbenzothiazoline-6-sulfonic acid free radicals, but the antioxidant activity rose in seeds submitted to recovery after stress. Positive correlation was therefore demonstrated between the total content of phenolic acids in germinating grapevine seeds and the reducing power of extracts obtained from these seeds and their free radical scavenging activity. The results suggest that osmotic stress inhibits the activity of

  20. Sex differences in stress effects on response and spatial memory formation.

    Science.gov (United States)

    Guenzel, Friederike M; Wolf, Oliver T; Schwabe, Lars

    2014-03-01

    Stress and stress hormones are known to affect learning and memory processes. However, although effects of stress on hippocampus-dependent declarative learning and memory are well-documented, relatively little attention has been paid to the impact of stress on striatum-dependent stimulus-response (S-R) learning and memory. Recent evidence indicates that glucocorticoid stress hormones shortly after learning enhance S-R memory consolidation, whereas stress prior to retention testing impairs S-R memory retrieval. Whether stress affects also the acquisition of S-R memories in humans remains unclear. For this reason, we examined here the effects of acute stress on S-R memory formation and contrasted these stress effects with those on hippocampus-dependent spatial memory. Healthy men and women underwent a stressor (socially evaluated cold pressor test, SECPT) or a control manipulation before they completed an S-R task and two spatial learning tasks. Memory was assessed one week later. Our data showed that stress impaired S-R memory performance in men but not in women. Conversely, spatial memory was impaired by stress in women but not in men. These findings provide further evidence that stress may alter learning and memory processes beyond the hippocampus. Moreover, our data underline that participants' sex may play a critical role in the impact of stress on multiple memory systems. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. The Effects of Silymarin on Oxidative Status and Bone Characteristics in Japanese Quail Subjected to Oxidative Stress Induced by Carbon Tetrachloride

    Directory of Open Access Journals (Sweden)

    Moradi F

    2017-10-01

    Full Text Available This experiment was conducted to assess the effects of Silymarin on oxidative status, bone characteristics, and some blood parameters in Japanese quail subjected to oxidative stress induced by carbon tetrachloride (CCl4. The experiment was performed as a completely randomized design with four replicates, each with 30 birds, using a 2 × 2 factorial arrangement with two doses of Silymarin (0 and 1 mL/kg BW and CCl4 (0 and 1 mL/kg BW. Results revealed that the interaction between Silymarin and CCl4on concentrations of total cholesterol, triglycerides, glucose, albumin, calcium, and alkaline phosphatase were significant (P < 0.05. In contrast, concentrations of phosphorus, total protein, and high density lipoprotein-cholesterol in blood serum did not differ between experimental treatments. Experimental treatments had a significant effect on superoxide dismutase activity in blood serum (P < 0.05, but not on glutathione peroxide activity and malondialdehyde concentration. Experimental treatments significantly affected the weight, thickness, and external and internal diameters of tibia bone (P < 0.05, but not its length, ash, volume, and density. This study shows that Silymarin has potential to attenuate adverse effects of oxidative stress induced by CCl4 in Japanese quail.

  2. Effect of acute salinity stress on ion homeostasis, Na+/K+-ATPase and histological structure in sea cucumber Apostichopus japonicus.

    Science.gov (United States)

    Geng, Chenfan; Tian, Yi; Shang, Yanpeng; Wang, Liqiang; Jiang, Yanan; Chang, Yaqing

    2016-01-01

    Sea cucumbers ( Apostichopus japonicus ) are an imperiled fauna exposed to a variety of environmental condition such as salinity and studies are urgently needed to assess their effects to guide aquaculture efforts. The effects of acute salinity stress on coelomic fluid osmotic pressure, ion concentrations, the activity of Na + /K + -ATPase in respiratory trees and the histological variations were measured to evaluate the salinity tolerance of sea cucumbers. Significant correlations in osmotic pressure were observed between coelomic fluid and ambient environmental salinity. In coelomic fluid, Na + concentration was observed fluctuated during salinity 18 psu and the inflection point presented at the 6 h. The Na + /K + -ATPase activity in respiratory trees indicated the "U-shaped" fluctuant change and the change trend was opposite with the Na + concentration. The ions (K + , Cl - ) concentration decreased and showed the same tendency at salinity 40 psu with salinity 18 psu. The total coelomocytes counts and phagocytosis of coelomic fluid Na + /K + -ATPase activity indicated fluctuating changes under different salinity stress. Histological variation revealed a negative relation between decreasing salt concentration and tissue integrity. Tissue damages were significantly observed in intestines, muscles and tube feet under low salinity environment (18, 23 and 27 psu). The connective tissue in intestines of A. japonicus exposed to 18 and 23 psu damaged and partly separated from the mucosal epithelium. The significant variations occurred in tube feet, which presented the swelling in connective tissue and a fracture in longitudinal muscles under low salinity (18 psu). The morphological change of tube feet showed the shrinkage of connective tissue under high salinity (40 psu). The amount of infusoria in the respiratory trees decreased or even disappeared in salinity treatment groups (18 and 23 psu). The results inferred that osmoconformity and ionoregulation were

  3. The effects of propolis extract on ovarian tissue and oxidative stress in rats with maternal separation stress

    Directory of Open Access Journals (Sweden)

    Atefeh Arabameri

    2017-09-01

    Full Text Available Abstract Background: Stress in infancy has dramatic effects on different systems, including the nervous system, endocrine, immune, reproductive and etc. Objective: The purpose of this study was to investigate the effects of extract of Iranian propolis (EIP on ovarian tissue and oxidative stress in rats with maternal separation stress. Materials and Methods: 48 immature female rats were divided randomly into six groups. 1 Control group, 2 Control group+saline, 3 Stress group, includes infants that were separated from their mothers 6 hr/day, the 4th, 5th and 6th groups consisted of infants who in addition to daily stress received 50, 100 and 200 mg/kg of EIP, respectively. Then serum corticosterone, 17-beta-estradiol, malondialdehyde, total superoxide dismutase, glutathione peroxidase and ferric reducing antioxidant power levels were measured. The ovarian sections were stained by H&E, PAS, and TUNEL methods and were studied with optical microscopy. Results: Stress increased the blood serum corticosterone levels and 17-beta-estradiol reduced significantly (p<0.001 and EIP prevented from this changes (p<0.01. EIP significantly increased the number of ovarian follicles, oocytes and oocytes diameter in neonatal rat following stress (p<0.01. EIP also significantly decreased the number of atretic follicles, TUNEL+granulosa cells, malondialdehyde levels and increased ferric reducing antioxidant power, total superoxide dismutase and glutathione peroxidase serum levels in neonatal rats following stress. The dose of 200 mg/kg EIP was more effective. Conclusion: This Study showed that the Iranian Propolis significantly could prevent oxidative stress and histopathological changes in the ovary of the neonatal rat the following stress.

  4. ADRA2B genotype modulates effects of acute psychosocial stress on emotional memory retrieval in healthy young men.

    Science.gov (United States)

    Li, Shijia; Weerda, Riklef; Guenzel, Friederike; Wolf, Oliver T; Thiel, Christiane M

    2013-07-01

    Previous studies have shown that acute psychosocial stress impairs retrieval of declarative memory with emotional material being especially sensitive to this effect. A functional deletion variant of the ADRA2B gene encoding the α2B-adrenergic receptor has been shown to increase emotional memory and neural activity in the amygdala. We investigated the effects of acute psychosocial stress and the ADRA2B allele on recognition memory for emotional and neutral faces. Fourty-two healthy, non-smoker male volunteers (30 deletion carriers, 12 noncarriers) were tested with a face recognition paradigm. During encoding they were presented with emotional and neutral faces. One hour later, participants underwent either a stress ("Trier Social Stress Test (TSST)") or a control procedure which was followed immediately by the retrieval session where subjects had to indicate whether the presented face was old or new. Stress increased salivary cortisol concentrations, blood pressure and pulse and impaired recognition memory for faces independent of emotional valence and genotype. Participants showed generally slower reaction times to emotional faces. Carriers of the ADRA2B functional deletion variant showed an impaired recognition and slower retrieval of neutral faces under stress. Further, they were significantly slower in retrieving fearful faces in the control condition. The findings indicate that a genetic variation of the noradrenergic system may preserve emotional faces from stress-induced memory impairments seen for neutral faces and heighten reactivity to emotional stimuli under control conditions. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. Effects of Stress and MDMA on Hippocampal Gene Expression

    Directory of Open Access Journals (Sweden)

    Georg F. Weber

    2014-01-01

    Full Text Available MDMA (3,4-methylenedioxymethamphetamine is a substituted amphetamine and popular drug of abuse. Its mood-enhancing short-term effects may prompt its consumption under stress. Clinical studies indicate that MDMA treatment may mitigate the symptoms of stress disorders such as posttraumatic stress syndrome (PTSD. On the other hand, repeated administration of MDMA results in persistent deficits in markers of serotonergic (5-HT nerve terminals that have been viewed as indicative of 5-HT neurotoxicity. Exposure to chronic stress has been shown to augment MDMA-induced 5-HT neurotoxicity. Here, we examine the transcriptional responses in the hippocampus to MDMA treatment of control rats and rats exposed to chronic stress. MDMA altered the expression of genes that regulate unfolded protein binding, protein folding, calmodulin-dependent protein kinase activity, and neuropeptide signaling. In stressed rats, the gene expression profile in response to MDMA was altered to affect sensory processing and responses to tissue damage in nerve sheaths. Subsequent treatment with MDMA also markedly altered the genetic responses to stress such that the stress-induced downregulation of genes related to the circadian rhythm was reversed. The data support the view that MDMA-induced transcriptional responses accompany the persistent effects of this drug on neuronal structure/function. In addition, MDMA treatment alters the stress-induced transcriptional signature.

  6. When does stress help or harm? The effects of stress controllability and subjective stress response on Stroop performance.

    Directory of Open Access Journals (Sweden)

    Roselinde Kaiser Henderson

    2012-06-01

    Full Text Available The ability to engage in goal-directed behavior despite exposure to stress is critical to resilience. Questions of how stress can impair or improve behavioral functioning are important in diverse settings, from athletic competitions to academic testing to clinical therapy. Previous research suggests that controllability is a key factor in the impact of stress on behavior: learning how to control stressors buffers people from the negative effects of stress on subsequent cognitively demanding tasks. In addition, research suggests that the impact of stress on cognitive functioning depends on an individual’s response to stressors: moderate responses to stress can lead to improved performance while extreme (high or low responses can lead to impaired performance. The present studies tested the hypothesis that 1 learning to behaviorally control stressors leads to improved performance on a test of general executive functioning, the color-word Stroop, and that 2 this improvement emerges specifically for people who report moderate (subjective responses to stress. Experiment 1: Stroop performance, measured before and after a stress manipulation, was compared across groups of undergraduate participants (n=109. People who learned to control a noise stressor and received accurate performance feedback demonstrated reduced Stroop interference compared with people exposed to uncontrollable noise stress and feedback indicating an exaggerated rate of failure. In the group who learned behavioral control, those who reported moderate levels of stress showed the greatest reduction in Stroop interference. In contrast, in the group exposed to uncontrollable events, self-reported stress failed to predict performance. Experiment 2: In a second sample (n=90, we specifically investigated the role of controllability by keeping the rate of failure feedback constant across groups. In the group who learned behavioral control, those who reported moderate levels of stress

  7. Comparison of Effect of Sodium Silicate Particle Size in Nutritional Solution on Physiological Growth Trials of Maize Seedlings under Cadmium Stress

    Directory of Open Access Journals (Sweden)

    B Saadatian

    2017-10-01

    completely randomized design with four replications the. Treatments were included cadmium (CdSO4 stress levels (Zero, 50 and 100 μmol l-1 and sodium silicate treatments (control (Zero, Nano and micro particles with 2 mM concentration. Results and Discussion The results showed that the effects of sodium silicate, cadmium and their interactions on membrane stability index, specific leaf area, stomatal conductance, Fv/Fm, height, stem diameter, leaf area, shoot dry weight, root dry weight and shoot to root weight ratio was significant. But interaction between cadmium and sodium silicate on relative water content and leaf chlorophyll index was not significant. By increasing of Cd concentration, membrane stability index, chlorophyll index, Fv/Fm, relative water content, specific leaf area, stomatal conductance, height, stem diameter, leaf area, shoot dry weight and root dry weight trials reduced compared to control significantly. In no cadmium condition, sodium silicate nano-particles application reduced height, stem diameter, leaf area and shoot dry weight 12.8, 9, 34.2 and 23.2% compared to control, respectively. In contrast, using of micro particles in non-stress condition, had a positive effect on above mentioned traits. But in 50 μmol l-1 Cd, nano-particles increased membrane stability index, specific leaf area, stomatal conductance, stem diameter and shoot dry weight trials, significantly. At highest concentration of cadmium, effect of micro particles on membrane stability index, stomatal conductance and shoot to root was higher than nano-particles. Also, using of nano particles had a positive effect on above mentioned traits in Cd stress condition. In general, application of nano particles in non-cadmium stress conditions had phytotoxicity effects on corn and only in cadmium stress condition, the effect of these particles showed their positive effect. Conclusions In general, silicon nanoparticles were only beneficial effect of cadmium stress. Hence, the use of sodium

  8. Acute stress blocks the caffeine-induced enhancement of contextual memory retrieval in mice.

    Science.gov (United States)

    Pierard, Chistophe; Krazem, Ali; Henkous, Nadia; Decorte, Laurence; Béracochéa, Daniel

    2015-08-15

    This study investigated in mice the dose-effect of caffeine on memory retrieval in non-stress and stress conditions. C57 Bl/6 Jico mice learned two consecutive discriminations (D1 and D2) in a four-hole board which involved either distinct contextual (CSD) or similar contextual (SSD) cues. All mice received an i.p. injection of vehicle or caffeine (8, 16 or 32mg/kg) 30min before the test session. Results showed that in non-stress conditions, the 16mg/kg caffeine dose induced a significant enhancement of D1 performance in CSD but not in SSD. Hence, we studied the effect of an acute stress (electric footshocks) administered 15min before the test session on D1 performance in caffeine-treated mice. Results showed that stress significantly decreased D1 performance in vehicle-treated controls and the memory-enhancing effect induced by the 16mg/kg caffeine dose in non-stress condition is no longer observed. Interestingly, whereas caffeine-treated mice exhibited weaker concentrations of plasma corticosterone as compared to vehicles in non-stress condition, stress significantly increased plasma corticosterone concentrations in caffeine-treated mice which reached similar level to that of controls. Overall, the acute stress blocked both the endocrinological and memory retrieval enhancing effects of caffeine. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Effect of heat stress on adipokines and some blood metabolites in goats from Jordan.

    Science.gov (United States)

    Al-Dawood, Amani

    2017-02-01

    To date and to the best of our knowledge, there have been no available data on the interaction between heat stress (HS) and secretion of adipokines and some blood metabolites in Baladi goats from Jordan. Therefore, this study aimed at evaluating the changes in leptin, adiponectin, non-ester fatty acid (NEFA) and beta-hydroxybutyrate (BHB) concentrations in Baladi goats under HS conditions in Jordan. Six goats were exposed to direct solar radiation versus six goats exposed to shade regimen. Blood samples were collected and serum concentrations of leptin, adiponectin, NEFA and BHB were measured. Ambient temperature, relative humidity (RH) and body weight (BW) were recorded. Results indicated that leptin and adiponectin concentrations were significantly increased under HS. The concentration of NEFA was significantly increased under HS at the 7th and 14th days of the experiment, while mean total concentration of NEFA was not significantly affected by HS. Neither weekly nor mean total concentrations of BHB were significantly affected by HS during the experimental period. In conclusion, HS is associated with changes in leptin and adiponectin concentrations in Baladi goats. Heat-stressed goats were able to keep their blood NEFA and BHB concentrations similar to those of thermo-neutral goats. © 2016 Japanese Society of Animal Science.

  10. Love-type wave propagation in a pre-stressed viscoelastic medium influenced by smooth moving punch

    Science.gov (United States)

    Singh, A. K.; Parween, Z.; Chatterjee, M.; Chattopadhyay, A.

    2015-04-01

    In the present paper, a mathematical model studying the effect of smooth moving semi-infinite punch on the propagation of Love-type wave in an initially stressed viscoelastic strip is developed. The dynamic stress concentration due to the punch for the force of a constant intensity has been obtained in the closed form. Method based on Weiner-hopf technique which is indicated by Matczynski has been employed. The study manifests the significant effect of various affecting parameters viz. speed of moving punch associated with Love-type wave speed, horizontal compressive/tensile initial stress, vertical compressive/tensile initial stress, frequency parameter, and viscoelastic parameter on dynamic stress concentration due to semi-infinite punch. Moreover, some important peculiarities have been traced out and depicted by means of graphs.

  11. Effects of co-administration of fluoxetine or tianeptine with metyrapone on immobility time and plasma corticosterone concentration in rats subjected to the forced swim test.

    Science.gov (United States)

    Rogóz, Zofia; Skuza, Grazyna; Leśkiewicz, Monika; Budziszewska, Bogusława

    2008-01-01

    Major depression is frequently associated with hyperactivity of the hypothalamic-pituitary-adrenocortical axis, and glucocorticoid synthesis inhibitors have been shown to exert antidepressant action. The aim of the present study was to examine the effect of co-administration of fluoxetine or tianeptine with metyrapone on immobility time and plasma corticosterone concentration in male Wistar rats subjected to the forced swim test. Metyrapone alone (50 mg/kg, but not 25 mg/kg) reduced the immobility time of rats in the forced swim test; moreover, both doses tested (25 and 50 mg/kg), dose-dependently decreased the stress-induced plasma corticosterone concentration. Joint administration of fluoxetine or tianeptine (10 mg/kg) and metyrapone (25 mg/kg - a dose inactive per se) exhibited antidepressant-like activity in the forced swim test in rats. WAY 100636 (a 5-HT(1A) antagonist), but not prazosin (an alpha(1)-adrenergic antagonist), used in doses ineffective in the forced swim test, inhibited the antidepressant-like effect induced by co-administration of fluoxetine or tianeptine with metyrapone (25 mg/kg). Combined treatment of fluoxetine or tianeptine and metyrapone inhibited stress-induced corticosterone secretion to a similar extent as metyrapone alone. The obtained results indicate that metyrapone potentiates the antidepressant-like activity of fluoxetine or tianeptine and that, among other mechanisms, 5-HT(1A) receptors may play some role in this effect. Moreover, metyrapone exerts a beneficial effect on the stress-induced increase in plasma corticosterone concentration. These findings suggest that the co-administration of metyrapone and an antidepressant drug may be useful for the treatment of drug-resistant depression and/or depression associated with a high cortisol level.

  12. Stress control in electrodeposited CoFe films—Experimental study and analytical model

    International Nuclear Information System (INIS)

    Brankovic, Stanko R.; Kagajwala, Burhanuddin; George, Jinnie; Majkic, Goran; Stafford, Gery; Ruchhoeft, Paul

    2012-01-01

    Work investigating the effect of saccharin as an additive on growth stress and structure of electrodeposited CoFe films is presented. The saccharin concentrations were in the range between 0 g L −1 and 1.5 g L −1 . The stress measurements are performed in situ during electrodeposition of CoFe films using cantilever-bending method (curvature measurements). The structure of CoFe films was studied by transmission electron microscopy and X-ray diffraction. Results show that growth stress is a decreasing function of saccharin concentration. No appreciable change in composition, grain size, orientation or texture of CoFe films are observed with increasing saccharin content in solution. The growth stress dependence on saccharin concentration is discussed within the framework of analytical model, which directly links the observed stress decrease with the apparent saccharin coverage of the CoFe film surface during the electrodeposition process.

  13. Synergetic effects of radiation stress and hot-carrier stress on the current gain of npn bipolar junction transistors

    International Nuclear Information System (INIS)

    Witczak, S.C.; Kosier, S.L.; Schrimpf, R.D.; Galloway, K.F.

    1994-01-01

    The combined effects of ionizing radiation and hot-carrier stress on the current gain of npn bipolar junction transistors were investigated. The analysis was carried out experimentally by examining the consequences of interchanging the order in which the two stress types were applied to identical transistors which were stressed to various levels of damage. The results indicate that the hot-carrier response of the transistor is improved by radiation damage, whereas hot-carrier damage has little effect on subsequent radiation stress. Characterization of the temporal progression of hot-carrier effects revealed that hot-carrier stress acts initially to reduce excess base current and improve current gain in irradiated transistors. PISCES simulations show that the magnitude of the peak electric-field within the emitter-base depletion region is reduced significantly by net positive oxide charges induced by radiation. The interaction of the two stress types is explained in a qualitative model based on the probability of hot-carrier injection determined by radiation damage and on the neutralization and compensation of radiation-induced positive oxide charges by injected electrons. The result imply that a bound on damage due to the combined stress types is achieved when hot-carrier stress precedes any irradiation

  14. Psychophysiological effects of yoga on stress in college students.

    Science.gov (United States)

    Tripathi, Mahesh Narain; Kumari, Sony; Ganpat, Tikhe Sham

    2018-01-01

    College students are vulnerable to a critical period in developmental maturation, facing rigorous academic work, and learning how to function independently. Physical activities such as running and bicycling have been shown to improve mood and relieve stress. However, college students often have low levels of physical activity. Yoga is an ancient physical and mental activity that affects mood and stress. However, studies examining the psychophysiological effects of yoga are rare in peer-reviewed journals. The aim of this study is to establish preliminary evidence for the psychophysiological effects of yoga on stress in young-adult college students. The present study suggests that yoga has positive effects on a psychophysiological level that leads to decreased levels of stress in college student. Further research is needed to examine the extent to which different types of yogic practices address the needs of different college subpopulations (e.g., overweight, sedentary, and smokers).

  15. Psychophysiological effects of yoga on stress in college students

    Directory of Open Access Journals (Sweden)

    Mahesh Narain Tripathi

    2018-01-01

    Full Text Available College students are vulnerable to a critical period in developmental maturation, facing rigorous academic work, and learning how to function independently. Physical activities such as running and bicycling have been shown to improve mood and relieve stress. However, college students often have low levels of physical activity. Yoga is an ancient physical and mental activity that affects mood and stress. However, studies examining the psychophysiological effects of yoga are rare in peer-reviewed journals. The aim of this study is to establish preliminary evidence for the psychophysiological effects of yoga on stress in young-adult college students. The present study suggests that yoga has positive effects on a psychophysiological level that leads to decreased levels of stress in college student. Further research is needed to examine the extent to which different types of yogic practices address the needs of different college subpopulations (e.g., overweight, sedentary, and smokers.

  16. Effects of stress on decisions under uncertainty: A meta-analysis.

    Science.gov (United States)

    Starcke, Katrin; Brand, Matthias

    2016-09-01

    [Correction Notice: An Erratum for this article was reported in Vol 142(9) of Psychological Bulletin (see record 2016-39486-001). It should have been reported that the inverted u-shaped relationship between cortisol stress responses and decision-making performance was only observed in female, but not in male participants as suggested by the study by van den Bos, Harteveld, and Stoop (2009). Corrected versions of the affected sentences are provided.] The purpose of the present meta-analysis was to quantify the effects that stress has on decisions made under uncertainty. We hypothesized that stress increases reward seeking and risk taking through alterations of dopamine firing rates and reduces executive control by hindering optimal prefrontal cortex functioning. In certain decision situations, increased reward seeking and risk taking is dysfunctional, whereas in others, this is not the case. We also assumed that the type of stressor plays a role. In addition, moderating variables are analyzed, such as the hormonal stress response, the time between stress onset and decisions, and the participants' age and gender. We included studies in the meta-analysis that investigated decision making after a laboratory stress-induction versus a control condition (k = 32 datasets, N = 1829 participants). A random-effects model revealed that overall, stress conditions lead to decisions that can be described as more disadvantageous, more reward seeking, and more risk taking than nonstress conditions (d = .17). In those situations in which increased reward seeking and risk taking is disadvantageous, stress had significant effects (d = .26), whereas in other situations, no effects were observed (d = .01). Effects were observed under processive stressors (d = .19), but not under systemic ones (d = .09). Moderation analyses did not reveal any significant results. We concluded that stress deteriorates overall decision-making performance through the mechanisms proposed. The effects differ

  17. Dynamic changes in saliva after acute mental stress

    Science.gov (United States)

    Naumova, Ella A.; Sandulescu, Tudor; Bochnig, Clemens; Khatib, Philipp Al; Lee, Wing-Kee; Zimmer, Stefan; Arnold, Wolfgang H.

    2014-01-01

    Stress-related variations of fluoride concentration in supernatant saliva and salivary sediment, salivary cortisol, total protein and pH after acute mental stress were assessed. The hypothesis was that stress reactions have no influence on these parameters. Thirty-four male students were distributed into two groups: first received the stress exposure followed by the same protocol two weeks later but without stress exposure, second underwent the protocol without stress exposure followed by the stress exposure two weeks later. The stressor was a public speech followed by tooth brushing. Saliva was collected before, immediately after stress induction and immediately, at 10, 30 and 120 min. after tooth brushing. Cortisol concentrations, total protein, intraoral pH, and fluoride content in saliva were measured. The data were analyzed statistically. Salivary sediment was ca 4.33% by weight of whole unstimulated saliva. Fluoride bioavailability was higher in salivary sediment than in supernatant saliva. The weight and fluoride concentration was not altered during 2 hours after stress exposure. After a public speech, the salivary cortisol concentration significantly increased after 20 minutes compared to the baseline. The salivary protein concentration and pH also increased. Public speaking influences protein concentration and salivary pH but does not alter the fluoride concentration of saliva. PMID:24811301

  18. Effects of Consolidation Stress State on Normally Consolidated Clay

    DEFF Research Database (Denmark)

    Lade, Poul V.

    2000-01-01

    The effect of consolidation stress state on the stress-strain and strength characteristics has been studied from experiments on undisturbed block samples of a natural, normally consolidated clay known as San Francisco Bay Mud. The results of experiments on K0-consolidated, hollow cylinder specimens...... and on isotropically consolidated, cubical specimens, both tested in triaxial compression and extension, clearly showed the influence of the undisturbed fabric as well as the effect of the initial consolidation stress states. While the K0-consolidated specimens appeared to retain their original fabric and exhibit...

  19. Protective effect of Rhus coriaria fruit extracts against hydrogen peroxide-induced oxidative stress in muscle progenitors and zebrafish embryos

    Directory of Open Access Journals (Sweden)

    Fadia Najjar

    2017-12-01

    Full Text Available Background and Purpose Oxidative stress is involved in normal and pathological functioning of skeletal muscle. Protection of myoblasts from oxidative stress may improve muscle contraction and delay aging. Here we studied the effect of R. coriaria sumac fruit extract on human myoblasts and zebrafish embryos in conditions of hydrogen peroxide-induced oxidative stress. Study Design and Methods Crude ethanolic 70% extract (CE and its fractions was obtained from sumac fruits. The composition of sumac ethyl acetate EtOAc fraction was studied by 1H NMR. The viability of human myoblasts treated with CE and the EtOAc fraction was determined by trypan blue exclusion test. Oxidative stress, cell cycle and adhesion were analyzed by flow cytometry and microscopy. Gene expression was analyzed by qPCR. Results The EtOAc fraction (IC50 2.57 µg/mL had the highest antioxidant activity and exhibited the best protective effect against hydrogen peroxide-induced oxidative stress. It also restored cell adhesion. This effect was mediated by superoxide dismutase 2 and catalase. Pre-treatment of zebrafish embryos with low concentrations of the EtOAc fraction protected them from hydrogen peroxide-induced death in vivo. 1H NMR analysis revealed the presence of gallic acid in this fraction. Conclusion Rhus coriaria extracts inhibited or slowed down the progress of skeletal muscle atrophy by decreasing oxidative stress via superoxide dismutase 2 and catalase-dependent mechanisms.

  20. Effect of magnetic attachment with stress breaker on lateral stress to abutment tooth under overdenture.

    Science.gov (United States)

    Gonda, T; Ikebe, K; Ono, T; Nokubi, T

    2004-10-01

    Recently, a newly developed magnetic attachment with stress breaker was used in retentive components in overdentures. Excessive lateral stress has a more harmful effect on natural teeth than axial stress, and the magnetic attachment with stress breaker is expected to reduce lateral forces on abutment teeth and protect it teeth from excessive stress. However, the properties of this retainer have not yet been determined experimentally. This study compares the lateral forces on abutment teeth for three retainers under loading on the denture base in a model study. A mandibular simulation model is constructed to measure lateral stress. Three types of retentive devices are attached to the canine root. These devices include the conventional root coping, the conventional magnetic attachment and the new magnetic attachment with stress breaker. For each retentive device, load is generated on the occlusal table of the model overdenture, and the lateral stress on the canine root and the displacement of the overdenture measured. The magnetic attachment with stress breaker does not displace the denture and exhibits lower lateral stress in the canine root than conventional root coping and magnetic attachments.