Prenatal stress may increase vulnerability to life events

DEFF Research Database (Denmark)

Hougaard, Karin S; Andersen, Maibritt B; Kjaer, Sanna L

2005-01-01

Prenatal stress has been associated with a variety of alterations in the offspring. The presented observations suggest that rather than causing changes in the offspring per se, prenatal stress may increase the organism's vulnerability to aversive life events. Offspring of rat dams stressed...

Differential Effects of Acute Stress on Anticipatory and Consummatory Phases of Reward Processing

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Kumar, Poornima; Berghorst, Lisa H.; Nickerson, Lisa D.; Dutra, Sunny J.; Goer, Franziska; Greve, Douglas; Pizzagalli, Diego A.

2014-01-01

Anhedonia is one of the core symptoms of depression and has been linked to blunted responses to rewarding stimuli in striatal regions. Stress, a key vulnerability factor for depression, has been shown to induce anhedonic behavior, including reduced reward responsiveness in both animals and humans, but the brain processes associated with these effects remain largely unknown in humans. Emerging evidence suggests that stress has dissociable effects on distinct components of reward processing, as it has been found to potentiate motivation/‘wanting’ during the anticipatory phase but reduce reward responsiveness/‘liking’ during the consummatory phase. To examine the impact of stress on reward processing, we used a monetary incentive delay (MID) task and an acute stress manipulation (negative performance feedback) in conjunction with functional magnetic resonance imaging (fMRI). Fifteen healthy participants performed the MID task under no-stress and stress conditions. We hypothesized that stress would have dissociable effects on the anticipatory and consummatory phases in reward-related brain regions. Specifically, we expected reduced striatal responsiveness during reward consumption (mirroring patterns previously observed in clinical depression) and increased striatal activation during reward anticipation consistent with non-human findings. Supporting our hypotheses, significant Phase (Anticipation/Consumption) x Stress (Stress/No-stress) interactions emerged in the putamen, nucleus accumbens, caudate and amygdala. Post-hoc tests revealed that stress increased striatal and amygdalar activation during anticipation but decreased striatal activation during consumption. Importantly, stress-induced striatal blunting was similar to the profile observed in clinical depression under baseline (no-stress) conditions in prior studies. Given that stress is a pivotal vulnerability factor for depression, these results offer insight to better understand the etiology of this

Beyond Diabetes: Does Obesity-Induced Oxidative Stress Drive the Aging Process?

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Adam B. Salmon

2016-07-01

Full Text Available Despite numerous correlative data, a causative role for oxidative stress in mammalian longevity has remained elusive. However, there is strong evidence that increased oxidative stress is associated with exacerbation of many diseases and pathologies that are also strongly related to advanced age. Obesity, or increased fat accumulation, is one of the most common chronic conditions worldwide and is associated with not only metabolic dysfunction but also increased levels of oxidative stress in vivo. Moreover, obesity is also associated with significantly increased risks of cardiovascular disease, neurological decline and cancer among many other diseases as well as a significantly increased risk of mortality. In this review, we investigate the possible interpretation that the increased incidence of these diseases in obesity may be due to chronic oxidative stress mediating segmental acceleration of the aging process. Understanding how obesity can alter cellular physiology beyond that directly related to metabolic function could open new therapeutic areas of approach to extend the period of healthy aging among people of all body composition.

Growth on Alpha-Ketoglutarate Increases Oxidative Stress Resistance in the Yeast Saccharomyces cerevisiae

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Maria Bayliak

2017-01-01

Full Text Available Alpha-ketoglutarate (AKG is an important intermediate in cell metabolism, linking anabolic and catabolic processes. The effect of exogenous AKG on stress resistance in S. cerevisiae cells was studied. The growth on AKG increased resistance of yeast cells to stresses, but the effects depended on AKG concentration and type of stressor. Wild-type yeast cells grown on AKG were more resistant to hydrogen peroxide, menadione, and transition metal ions (Fe2+ and Cu2+ but not to ethanol and heat stress as compared with control ones. Deficiency in SODs or catalases abolished stress-protective effects of AKG. AKG-supplemented growth led to higher values of total metabolic activity, level of low-molecular mass thiols, and activities of catalase and glutathione reductase in wild-type cells compared with the control. The results suggest that exogenous AKG may enhance cell metabolism leading to induction of mild oxidative stress. It turn, it results in activation of antioxidant system that increases resistance of S. cerevisiae cells to H2O2 and other stresses. The presence of genes encoding SODs or catalases is required for the expression of protective effects of AKG.

Acute stress shifts the balance between controlled and automatic processes in prospective memory.

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Möschl, Marcus; Walser, Moritz; Plessow, Franziska; Goschke, Thomas; Fischer, Rico

2017-10-01

In everyday life we frequently rely on our abilities to postpone intentions until later occasions (prospective memory; PM) and to deactivate completed intentions even in stressful situations. Yet, little is known about the effects of acute stress on these abilities. In the present work we investigated the impact of acute stress on PM functioning under high task demands. (1) Different from previous studies, in which intention deactivation required mostly low processing demands, we used salient focal PM cues to induce high processing demands during intention-deactivation phases. (2) We systematically manipulated PM-monitoring demands in a nonfocal PM task that required participants to monitor for either one or six specific syllables that could occur in ongoing-task words. Eighty participants underwent the Trier Social Stress Test, a standardized stress induction protocol, or a standardized control situation, before performing a computerized PM task. Our primary interests were whether PM performance, PM-monitoring costs, aftereffects of completed intentions and/or commission-error risk would differ between stressed and non-stressed individuals and whether these effects would differ under varying task demands. Results revealed that PM performance and aftereffects of completed intentions during subsequent performance were not affected by acute stress induction, replicating previous findings. Under high demands on intention deactivation (focal condition), however, acute stress produced a nominal increase in erroneous PM responses after intention completion (commission errors). Most importantly, under high demands on PM monitoring (nonfocal condition), acute stress led to a substantial reduction in PM-monitoring costs. These findings support ideas of selective and demand-dependent effects of acute stress on cognitive functioning. Under high task demands, acute stress might induce a shift in processing strategy towards resource-saving behavior, which seems to increase the

A novel bread making process using salt-stressed Baker's yeast.

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Yeh, Lien-Te; Charles, Albert Linton; Ho, Chi-Tang; Huang, Tzou-Chi

2009-01-01

By adjusting the mixing order of ingredients in traditional formula, an innovative bread making process was developed. The effect of salt-stressed Baker's yeast on bread dough of different sugar levels was investigated. Baker's yeast was stressed in 7% salt solution then mixed into dough, which was then evaluated for fermentation time, dough fermentation producing gas, dough expansion, bread specific volumes, and sensory and physical properties. The results of this study indicated that salt-stressed Baker's yeast shortened fermentation time in 16% and 24% sugar dough. Forty minutes of salt stress produced significant amount of gas and increased bread specific volumes. The bread was softer and significantly improved sensory properties for aroma, taste, and overall acceptability were obtained.

Flow and Stress Field Analysis of Different Fluids and Blades for Fermentation Process

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Cheng-Chi Wang

2014-02-01

Full Text Available Fermentation techniques are applied for the biotechnology and are widely used for food manufacturing, materials processing, chemical reaction, and so forth. Different fluids and types of blades in the tank for fermentation cause distinct flow and stress field distributions on the surface between fluid and blade and various flow reactions in the tank appear. This paper is mainly focused on the analysis of flow field with different fluid viscosities and also studied the stress field acting on the blades with different scales and shapes of them under specific rotational speed. The results show that the viscosity of fluid influences the flow field and stress distributions on the blades. The maximum stress that acts on the blade is increased with the increasing of viscosity. On the other hand, the ratio of blade length to width influences stress distributions on the blade. At the same time, the inclined angle of blade is also the key parameter for the consideration of design and appropriate inclined angle of blade will decrease the maximum stress. The results provide effective means of gaining insights into the flow and stress distribution of fermentation process.

Acute psychosocial stress does not increase dysfunctional attitudes.

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Yeoh, Su Ying; Wilkinson, Paul

2014-11-01

Dysfunctional attitudes about oneself, the world and the future, measured quantitatively by Weissman's Dysfunctional Attitudes Scale (DAS), are thought to influence the onset and persistence of major depressive disorder. However, never-depressed individuals may also harbour latent negative schema which may become activated under stressful conditions, giving rise to dysfunctional negative cognitions. This study investigated whether everyday psychosocial stresses could be sufficient to activate dysfunctional self-schema and increase negative cognitions in a large group of healthy adolescents and a preliminary cohort of previously depressed adolescents. 92 never-depressed adolescents aged 17-19 and 18 previously depressed adolescents, recruited from the Cambridge ROOTS cohort, took either version A or B of the DAS at rest on day 1. On day 2, they were subjected to the Trier Social Stress Test, a psychosocial stress paradigm, 22 minutes after which they took the other version of DAS. Stress did not affect the DAS score in either group. Brief psychosocial stress does not appear to influence negative assumptions in healthy young adults with or without a past history of depression. It is possible that this is because dysfunctional assumptions, unlike self-schemas, are not latent. More long-term stresses may be needed to activate negative thoughts to a level where risk of depression is increased.

Field and polarity dependence of time-to-resistance increase in Fe-O films studied by constant voltage stress method

International Nuclear Information System (INIS)

Eriguchi, Koji; Ohta, Hiroaki; Ono, Kouichi; Wei Zhiqiang; Takagi, Takeshi

2009-01-01

Constant voltage stress (CVS) was applied to Fe-O films prepared by a sputtering process to investigate a stress-induced resistance increase leading to a fundamental mechanism for switching behaviors. Under the CVS, an abrupt resistance increase was found for both stress polarities. A conduction mechanism after the resistance increase exhibited non-Ohmic transport. The time-to-resistance increase (t r ) under the CVS was revealed to strongly depend on stress voltage as well as the polarity. From a polarity-dependent resistance increase determined by a time-zero measurement, the voltage and polarity-dependent t r were discussed on the basis of field- and structure-enhanced thermochemical reaction mechanisms

Acute Stress Influences Neural Circuits of Reward Processing

Directory of Open Access Journals (Sweden)

Anthony John Porcelli

2012-11-01

Full Text Available People often make decisions under aversive conditions such as acute stress. Yet, less is known about the process in which acute stress can influence decision-making. A growing body of research has established that reward-related information associated with the outcomes of decisions exerts a powerful influence over the choices people make and that an extensive network of brain regions, prominently featuring the striatum, is involved in the processing of this reward-related information. Thus, an important step in research on the nature of acute stress’ influence over decision-making is to examine how it may modulate responses to rewards and punishments within reward-processing neural circuitry. In the current experiment, we employed a simple reward processing paradigm – where participants received monetary rewards and punishments – known to evoke robust striatal responses. Immediately prior to performing each of two task runs, participants were exposed to acute stress (i.e., cold pressor or a no stress control procedure in a between-subjects fashion. No stress group participants exhibited a pattern of activity within the dorsal striatum and orbitofrontal cortex consistent with past research on outcome processing – specifically, differential responses for monetary rewards over punishments. In contrast, acute stress group participants’ dorsal striatum and orbitofrontal cortex demonstrated decreased sensitivity to monetary outcomes and a lack of differential activity. These findings provide insight into how neural circuits may process rewards and punishments associated with simple decisions under acutely stressful conditions.

Acute stress-induced cortisol elevations mediate reward system activity during subconscious processing of sexual stimuli

NARCIS (Netherlands)

Oei, N.Y.L.; Both, S.; van Heemst, D.; van der Grond, J.

2014-01-01

Stress is thought to alter motivational processes by increasing dopamine (DA) secretion in the brain's "reward system", and its key region, the nucleus accumbens (NAcc). However, stress studies using functional magnetic resonance imaging (fMRI), mainly found evidence for stress-induced decreases in

Do levels of perceived stress increase with increasing age after age 65? A population-based study.

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Osmanovic-Thunström, Almira; Mossello, Enrico; Åkerstedt, Torbjörn; Fratiglioni, Laura; Wang, Hui-Xin

2015-09-01

psychological and health-related stressors often occur in advanced ages, but little is known about perceived stress in adults aged 65 and over. This study aimed to test the hypothesis that levels of perceived stress increase with increasing age and to detect factors that may account for the association. a dementia-free cohort of 1,656 adults aged 66-97 years living at home or in institutions, participating in the Swedish National Aging and Care study, Kungsholmen (SNAC-K) was assessed for levels of perceived stress using the 10-item perceived stress scale (PSS). prevalence of high stress according to the top tertile of the population (PSS score 20+) was 7.8% in adults aged 81+ years, 7.5% in adults aged 72-78 and 6.2% in adults aged 66 years (P = 0.020). More women than men reported high stress, 8.3 versus 5.4% (P = 0.001). Levels of stress increased with increasing age (P = 0.001) in the linear regression model. This association remained after adjustment for demographic and psychosocial factors, but no longer was present after adjusting for health-related factors. health-related stress is highly prevalent in older adults and seems to play an important role in the association between levels of perceived stress and age in older adults. © The Author 2015. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Pad stress tests with increasing load for the diagnosis of stress urinary incontinence.

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Rimstad, Liv; Larsen, Elsa Skjønhaug; Schiøtz, Hjalmar A; Kulseng-Hanssen, Sigurd

2014-09-01

The aim of the study was to test the ability of pad stress tests with increasing load (supine, jumping on the floor, and jumping on a trampoline) to document stress incontinence in subjectively stress incontinent women. In this prospective study 147 subjectively stress and mixed incontinent women performed consecutively the three pad stress tests with a bladder volume of 300 ml. Nineteen women performed a second trampoline pad stress test to test repeatability of the test. Nine continent women performed a trampoline pad stress test in order to determine if subjectively continent women would leak during the test. Seventy-two women (49%) leaked during the supine, 136 (93%) leaked during the jumping, and 146 (99%) leaked during the trampoline pad stress test. The differences between pad stress tests were significant with P trampoline pad stress tests was high at 0.8. None of the nine continent women leaked during the trampoline pad stress test. The supine pad stress test has low sensitivity and is therefore often falsely negative. The jumping pad stress test is a simple test to perform and is satisfactory for everyday use. Subjectively stress incontinent women who do not leak during the jumping pad stress test may perform a trampoline pad stress test to document stress incontinence. The trampoline pad stress test is also simple to perform and detected leakage in 91% of the women who did not leak during the jumping pad stress test. © 2013 Wiley Periodicals, Inc.

Information Processing Bias in Post-traumatic Stress Disorder

OpenAIRE

Weber, Darren L

2008-01-01

This review considers theory and evidence for abnormal information processing in post-traumatic stress disorder (PTSD). Cognitive studies have indicated sensitivity in PTSD for traumatic information, more so than general emotional information. These findings were supported by neuroimaging studies that identify increased brain activity during traumatic cognition, especially in affective networks (including the amygdala, orbitofrontal and anterior cingulate cortex). In theory, it is proposed th...

Intraindividual change and variability in daily stress processes: Findings from two measurement-burst diary studies

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Sliwinski, Martin J.; Almeida, David M.; Smyth, Joshua; Stawski, Robert S.

2010-01-01

There is little longitudinal information on aging-related changes in emotional responses to negative events. The present manuscript examined intraindividual change and variability in the within-person coupling of daily stress and negative affect (NA) using data from two-measurement burst daily diary studies. Three main findings emerged. First, average reactivity to daily stress increased longitudinally, and this increase was evident across most the adult lifespan. Second, individual differences in emotional reactivity to daily stress exhibited long-term temporal stability, but this stability was greatest in midlife and decreased in old age. And third, reactivity to daily stress varied reliably within-persons (across-time), with individual exhibiting higher levels of reactivity during times when reporting high levels of global subject stress in previous month. Taken together, the present results emphasize the importance of modeling dynamic psychosocial and aging processes that operate across different time scales for understanding age-related changes in daily stress processes. PMID:20025399

Emotions and stress increase respiratory resistance in asthma.

Science.gov (United States)

Ritz, T; Steptoe, A; DeWilde, S; Costa, M

2000-01-01

Clinical reports suggest that various emotions and types of stress can precipitate asthmatic symptoms, but there is little experimental evidence to substantiate this claim. We studied the impact of different emotional states and stress on respiratory resistance in asthmatic and nonasthmatic individuals. Participants (24 asthmatic and 24 nonasthmatic patients) viewed short film sequences selected to induce anxiety, anger, depression, elation, happiness, contentment, or a neutral affective state and completed two stressful tasks, mental arithmetic to induce active coping efforts and viewing of medical slides to induce passive coping efforts. Oscillatory resistance, heart rate, blood pressure, baroreflex sensitivity, skin conductance level, respiration rate and volume, and self-reported affective state were measured throughout the session. Uniform increases in oscillatory resistance were found in all emotional states compared with the neutral state and during mental arithmetic in both groups. Asthmatic patients showed stronger reactions to the medical slides than healthy control subjects, with significant increases in oscillatory resistance, blood pressure, skin conductance level, and minute volume, as well as higher levels of self-reported depression, arousal, and shortness of breath. Changes in oscillatory resistance were inconsistently correlated with other physiological indices. Various emotional states and stress increase oscillatory resistance largely independently of concurrent increases in autonomic or ventilatory activity. The particular sensitivity of asthmatics to passive coping demand requires additional research.

Acute Stress Decreases but Chronic Stress Increases Myocardial Sensitivity to Ischemic Injury in Rodents.

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Eisenmann, Eric D; Rorabaugh, Boyd R; Zoladz, Phillip R

2016-01-01

Cardiovascular disease (CVD) is the largest cause of mortality worldwide, and stress is a significant contributor to the development of CVD. The relationship between acute and chronic stress and CVD is well evidenced. Acute stress can lead to arrhythmias and ischemic injury. However, recent evidence in rodent models suggests that acute stress can decrease sensitivity to myocardial ischemia-reperfusion injury (IRI). Conversely, chronic stress is arrhythmogenic and increases sensitivity to myocardial IRI. Few studies have examined the impact of validated animal models of stress-related psychological disorders on the ischemic heart. This review examines the work that has been completed using rat models to study the effects of stress on myocardial sensitivity to ischemic injury. Utilization of animal models of stress-related psychological disorders is critical in the prevention and treatment of cardiovascular disorders in patients experiencing stress-related psychiatric conditions.

Acute Stress Decreases but Chronic Stress Increases Myocardial Sensitivity to Ischemic Injury in Rodents

Science.gov (United States)

Eisenmann, Eric D.; Rorabaugh, Boyd R.; Zoladz, Phillip R.

2016-01-01

Cardiovascular disease (CVD) is the largest cause of mortality worldwide, and stress is a significant contributor to the development of CVD. The relationship between acute and chronic stress and CVD is well evidenced. Acute stress can lead to arrhythmias and ischemic injury. However, recent evidence in rodent models suggests that acute stress can decrease sensitivity to myocardial ischemia–reperfusion injury (IRI). Conversely, chronic stress is arrhythmogenic and increases sensitivity to myocardial IRI. Few studies have examined the impact of validated animal models of stress-related psychological disorders on the ischemic heart. This review examines the work that has been completed using rat models to study the effects of stress on myocardial sensitivity to ischemic injury. Utilization of animal models of stress-related psychological disorders is critical in the prevention and treatment of cardiovascular disorders in patients experiencing stress-related psychiatric conditions. PMID:27199778

Stress and reward processing in bipolar disorder: an fMRI study

Science.gov (United States)

Berghorst, Lisa H; Kumar, Poornima; Greve, Doug N; Deckersbach, Thilo; Ongur, Dost; Dutra, Sunny; Pizzagalli, Diego A

2016-01-01

Objectives A link between negative life stress and the onset of mood episodes in bipolar disorder (BD) has been established, but processes underlying such a link remain unclear. Growing evidence suggests that stress can negatively affect reward processing and related neurobiological substrates, indicating that a dysregulated reward system may provide a partial explanation. The aim of this study was to test the impact of stress on reward-related neural functioning in BD. Methods Thirteen euthymic or mildly depressed individuals with BD and 15 controls performed a Monetary Incentive Delay task while undergoing functional magnetic resonance imaging during no-stress and stress (negative psychosocial stressor involving poor performance feedback and threat of monetary deductions) conditions. Results In hypothesis-driven region-of- interest-based analyses, a significant group by condition interaction emerged in the amygdala during reward anticipation. Relative to controls, while anticipating a potential reward, subjects with BD were characterized by amygdalar hyperactivation in the no-stress condition but hypoactivation during stress. Moreover, relative to controls, subjects with BD had significantly larger amygdala volumes. After controlling for structural differences, the effects of stress on amygdalar function remained, whereas groups no longer differed during the no-stress condition. During reward consumption, a group by condition interaction emerged in the putamen due to increased putamen activation to rewards in participants with BD during stress, but an opposite pattern in controls. Conclusions Overall, findings highlight possible impairments in using reward-predicting cues to adaptively engage in goal-directed actions in BD, combined with stress-induced hypersensitivity to reward consumption. Potential clinical implications are discussed. PMID:27870507

Stress modulation of cognitive and affective processes

Science.gov (United States)

CAMPEAU, SERGE; LIBERZON, ISRAEL; MORILAK, DAVID; RESSLER, KERRY

2012-01-01

This review summarizes the major discussion points of a symposium on stress modulation of cognitive and affective processes, which was held during the 2010 workshop on the neurobiology of stress (Boulder, CO, USA). The four discussants addressed a number of specific cognitive and affective factors that are modulated by exposure to acute or repeated stress. Dr David Morilak discussed the effects of various repeated stress situations on cognitive flexibility, as assessed with a rodent model of attentional set-shifting task, and how performance on slightly different aspects of this test is modulated by different prefrontal regions through monoaminergic neurotransmission. Dr Serge Campeau summarized the findings of several studies exploring a number of factors and brain regions that regulate habituation of various autonomic and neuroendocrine responses to repeated audiogenic stress exposures. Dr Kerry Ressler discussed a body of work exploring the modulation and extinction of fear memories in rodents and humans, especially focusing on the role of key neurotransmitter systems including excitatory amino acids and brain-derived neurotrophic factor. Dr Israel Liberzon presented recent results on human decision-making processes in response to exogenous glucocorticoid hormone administration. Overall, these discussions are casting a wider framework on the cognitive/affective processes that are distinctly regulated by the experience of stress and some of the brain regions and neurotransmitter systems associated with these effects. PMID:21790481

Acute stress decreases but chronic stress increases myocardial sensitivity to ischemic injury in rodents

Directory of Open Access Journals (Sweden)

Eric D Eisenmann

2016-04-01

Full Text Available Cardiovascular disease is the largest cause of mortality worldwide, and stress is a significant contributor to the development of cardiovascular disease. The relationship between acute and chronic stress and cardiovascular disease is well-evidenced. Acute stress can lead to arrhythmias and ischemic injury. However, recent evidence in rodent models suggests that acute stress can decrease sensitivity to myocardial ischemia-reperfusion injury. Conversely, chronic stress is arrythmogenic and increases sensitivity to myocardial ischemia-reperfusion injury. Few studies have examined the impact of validated animal models of stress-related psychological disorders on the ischemic heart. This review examines the work that has been completed using rat models to study the effects of stress on myocardial sensitivity to ischemic injury. Utilization of animal models of stress-related psychological disorders is critical in the prevention and treatment of cardiovascular disorders in patients experiencing stress-related psychiatric conditions.

A framework for modelling the behaviour of a process control operator under stress

International Nuclear Information System (INIS)

Kan, C-C.F.; Roberts, P.D.; Smith, I.C.

1990-01-01

This paper proposes the basis for a framework for modelling effects of stress on the behaviour of a process control plant operator. The qualitative effects of stress on the cognitive processing ability of the operator are discussed. Stress is thought to mainly decrease the reasoning ability of the operator. The operator will experience increased rigidity in problem solving and the narrowing of his attention and perceptual field. At the same time, the operator will be increasingly reluctant in admitting that wrong decisions have been committed. Furthermore, he will revert to skill-based behaviours. The direct consequence of stress on the decision making mechanism of the operator is the selection of inappropriate choice of action. A formal representation of decision errors is proposed and various techniques are suggested for representing various mechanisms for decision error making. The degree of experience possessed by the operator is also an important factor to the operator's tolerance of stress. The framework also allows the experience of the operator to be integrated into the model. Such an operator model can be linked to a plant simulator and the complete behaviour of the plant then be simulated

Residual stress evaluation and curvature behavior of aluminum 7050 peen forming processed

International Nuclear Information System (INIS)

Oliveira, Rene Ramos de

2011-01-01

Shot peening is a superficial cold work process used to increase the fatigue life evaluated by residual stress measurements. The peen forming process is a variant of the shot peening process, where a curvature in the plate is obtained by the compression of the grains near to the surface. In this paper, the influence of the parameters such as: pressure of shot, ball shot size and thickness of aluminum 7050 samples with respect to residual stress profile and resulting arc height was studied. The evaluation of the residual stress profile was obtained by sin 2 ψ method. The results show that the formation of the curvature arc height is proportional to the shot peening pressure, of spheres size and inversely proportional to the thickness of the sample, and that stress concentration factor is larger for samples shot peened with small balls. On final of this paper presents an additional study on micro strain and average crystallite size, which can evaluate the profile of the samples after blasting. (author)

Acute stress increases depolarization-evoked glutamate release in the rat prefrontal/frontal cortex: the dampening action of antidepressants.

Directory of Open Access Journals (Sweden)

Laura Musazzi

2010-01-01

Full Text Available Behavioral stress is recognized as a main risk factor for neuropsychiatric diseases. Converging evidence suggested that acute stress is associated with increase of excitatory transmission in certain forebrain areas. Aim of this work was to investigate the mechanism whereby acute stress increases glutamate release, and if therapeutic drugs prevent the effect of stress on glutamate release.Rats were chronically treated with vehicle or drugs employed for therapy of mood/anxiety disorders (fluoxetine, desipramine, venlafaxine, agomelatine and then subjected to unpredictable footshock stress. Acute stress induced marked increase in depolarization-evoked release of glutamate from synaptosomes of prefrontal/frontal cortex in superfusion, and the chronic drug treatments prevented the increase of glutamate release. Stress induced rapid increase in the circulating levels of corticosterone in all rats (both vehicle- and drug-treated, and glutamate release increase was blocked by previous administration of selective antagonist of glucocorticoid receptor (RU 486. On the molecular level, stress induced accumulation of presynaptic SNARE complexes in synaptic membranes (both in vehicle- and drug-treated rats. Patch-clamp recordings of pyramidal neurons in the prefrontal cortex revealed that stress increased glutamatergic transmission through both pre- and postsynaptic mechanisms, and that antidepressants may normalize it by reducing release probability.Acute footshock stress up-regulated depolarization-evoked release of glutamate from synaptosomes of prefrontal/frontal cortex. Stress-induced increase of glutamate release was dependent on stimulation of glucocorticoid receptor by corticosterone. Because all drugs employed did not block either elevation of corticosterone or accumulation of SNARE complexes, the dampening action of the drugs on glutamate release must be downstream of these processes. This novel effect of antidepressants on the response to stress

Investigating Resulting Residual Stresses during Mechanical Forming Process

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Akinlabi, Stephen A.; Fatoba, Olawale S.; Mashinini, Peter M.; Akinlabi, Esther T.

2018-03-01

Most manufacturing processes such as machining, welding, heat treatment, laser forming, laser cladding and, laser metal deposition, etc. are subjected to a form of heat or energy to change the geometrical shape thus changing the inherent engineering and structural properties of the material. These changes often cause the development of locked up stresses referred to as residual stresses as a result of these activities. This study reports on the residual stresses developed due to the mechanical forming process to maintain a suitable structural integrity for the formed components. The result of the analysis through the X-ray diffraction confirmed that residual stresses were induced in the manufactured parts and further revealed that residual stresses were compressive in nature as found in the parent material but with values less than the parent material.

Overprotective social support leads to increased cardiovascular and subjective stress reactivity.

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Zniva, Richard; Pauli, Paul; Schulz, Stefan M

2017-02-01

Self-determination theory suggests that autonomy-enhancing social support helps individuals to perceive stressors as challenging rather than stressing. Overprotective support may reduce stress in the short-run but undermines autonomy, thus hampering stress-coping in the long run, particularly when social support is terminated. Heartrate, blood-pressure and ratings were examined in N=44 undergraduate students receiving autonomy support (calculation steps) or overprotection (solutions) from a close friend or no support for solving arithmetic tasks as well as during a subsequent stress-challenge (solving arithmetic tasks alone). Overprotection resulted in increased heartrate, diastolic blood-pressure, stress ratings, and decreased subjective control during stress-challenge. Autonomy support did not lead to unfavorable stress responding. The current findings are in line with assumptions derived from self-determination theory and indicate that autonomy support can help to prevent stress. Overprotection does not buffer stress and is associated with increased stress when discontinued. Copyright © 2016 Elsevier B.V. All rights reserved.

Progranulin causes adipose insulin resistance via increased autophagy resulting from activated oxidative stress and endoplasmic reticulum stress.

Science.gov (United States)

Guo, Qinyue; Xu, Lin; Li, Huixia; Sun, Hongzhi; Liu, Jiali; Wu, Shufang; Zhou, Bo

2017-01-31

Progranulin (PGRN) has recently emerged as an important regulator for insulin resistance. However, the direct effect of progranulin in adipose insulin resistance associated with the autophagy mechanism is not fully understood. In the present study, progranulin was administered to 3T3-L1 adipocytes and C57BL/6 J mice with/without specific inhibitors of oxidative stress and endoplasmic reticulum stress, and metabolic parameters, oxidative stress, endoplasmic reticulum stress and autophagy markers were assessed. Progranulin treatment increased iNOS expression, NO synthesis and ROS generation, and elevated protein expressions of CHOP, GRP78 and the phosphorylation of PERK, and caused a significant increase in Atg7 and LC3-II protein expression and a decreased p62 expression, and decreased insulin-stimulated tyrosine phosphorylation of IRS-1 and glucose uptake, demonstrating that progranulin activated oxidative stress and ER stress, elevated autophagy and induced insulin insensitivity in adipocytes and adipose tissue of mice. Interestingly, inhibition of iNOS and ER stress both reversed progranulin-induced stress response and increased autophagy, protecting against insulin resistance in adipocytes. Furthermore, the administration of the ER stress inhibitor 4-phenyl butyric acid reversed the negative effect of progranulin in vivo. Our findings showed the clinical potential of the novel adipokine progranulin in the regulation of insulin resistance, suggesting that progranulin might mediate adipose insulin resistance, at least in part, by inducing autophagy via activated oxidative stress and ER stress.

Process induced residual stresses and distortions in pultrusion

DEFF Research Database (Denmark)

Baran, Ismet; Tutum, Cem Celal; Nielsen, Michael Wenani

2013-01-01

In the present study, a coupled 3D transient Eulerian thermo-chemical analysis together with a 2D plane strain Lagrangian mechanical analysis of the pultrusion process, which has not been considered until now, is carried out. The development of the process induced residual stresses and strains...... together with the distortions are predicted during the pultrusion in which the cure hardening instantaneous linear elastic (CHILE) approach is implemented. At the end of the process, tension stresses prevail for the inner region of the composite since the curing rate is higher here as compared to the outer...... regions where compression stresses are obtained. The separation between the heating die and the part due to shrinkage is also investigated using a mechanical contact formulation at the die-part interface. The proposed approach is found to be efficient and fast for the calculation of the residual stresses...

Acute stress-induced cortisol elevations mediate reward system activity during subconscious processing of sexual stimuli

OpenAIRE

Oei, Nicole Y. L.; Both, Stephanie; van Heemst, Diana; van der Grond, Jeroen

2014-01-01

Summary Stress is thought to alter motivational processes by increasing dopamine (DA) secretion in the brain’s ‘‘reward system’’, and its key region, the nucleus accumbens (NAcc). However, stress studies using functional magnetic resonance imaging (fMRI), mainly found evidence for stress-induced decreases in NAcc responsiveness toward reward cues. Results from both animal and human PETstudies indicate that the stress hormone cortisol may be crucial in the interaction between st...

Obesity-induced oxidative stress, accelerated functional decline with age and increased mortality in mice.

Science.gov (United States)

Zhang, Yiqiang; Fischer, Kathleen E; Soto, Vanessa; Liu, Yuhong; Sosnowska, Danuta; Richardson, Arlan; Salmon, Adam B

2015-06-15

Obesity is a serious chronic disease that increases the risk of numerous co-morbidities including metabolic syndrome, cardiovascular disease and cancer as well as increases risk of mortality, leading some to suggest this condition represents accelerated aging. Obesity is associated with significant increases in oxidative stress in vivo and, despite the well-explored relationship between oxidative stress and aging, the role this plays in the increased mortality of obese subjects remains an unanswered question. Here, we addressed this by undertaking a comprehensive, longitudinal study of a group of high fat-fed obese mice and assessed both their changes in oxidative stress and in their performance in physiological assays known to decline with aging. In female C57BL/6J mice fed a high-fat diet starting in adulthood, mortality was significantly increased as was oxidative damage in vivo. High fat-feeding significantly accelerated the decline in performance in several assays, including activity, gait, and rotarod. However, we also found that obesity had little effect on other markers of function and actually improved performance in grip strength, a marker of muscular function. Together, this first comprehensive assessment of longitudinal, functional changes in high fat-fed mice suggests that obesity may induce segmental acceleration of some of the aging process. Published by Elsevier Inc.

Information processing speed as a mediator between psychosocial stress and global cognition in older adults.

Science.gov (United States)

Foong, Hui F; Hamid, Tengku A; Ibrahim, Rahimah; Haron, Sharifah A

2018-01-01

The link between psychosocial stress and cognitive function is complex, and previous studies have indicated that it may be mediated by processing speed. Therefore, the main aim of this study was to examine whether processing speed mediates the association between psychosocial stress and global cognition in older adults. Moreover, the moderating role of gender in this model is examined as well. The study included 2322 community-dwelling older adults in Malaysia who were randomly selected through a multistage proportional cluster random sampling technique. Global cognition construct was measured by the Mini-Mental State Examination and Montreal Cognitive Assessment; psychosocial stress construct was measured by perceived stress, depression, loneliness, and neuroticism; and processing speed was assessed by the Digit Symbol Substitution Test. Structural equation modelling was used to analyze the mediation and moderation tests. Processing speed was found to partially mediate the relationship between psychosocial stress and global cognition (β in the direct model = -0.15, P cognition was found to be significant in men only, whereas the association between processing speed and global cognition was significant in men and women. Psychosocial stress may increase the likelihood that older adults will experience poor processing capacity, which could reduce their higher level cognition. Results indicate that there is a need to develop processing capacity intervention programmes for psychologically distressed older adults to prevent them from suffering cognitive decline. © 2018 Japanese Psychogeriatric Society.

NUMERICAL SIMULATION OF RESIDUAL STRESSES GENERATED IN THE WIRE DRAWING PROCESS FOR DIFFERENT PROCESS PARAMETERS

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Juliana Zottis

2014-03-01

Full Text Available The drawing process of steel bars is usually used to check better dimensional accuracy and mechanical properties to the material. In the other hand, the major concern found in manufacturing axes through this process is the appearance of distortion of shape. Such distortions are directly linked to the accumulation of residual stresses generated during the processes. As a result, this paper aims to study the influence of process parameters such as shape of puller, speed and lubrication used in wire drawing analyzing the accumulation of residual stress after the process. The stress analysis was performed by FEM being used two simulation software: Simufact.formingGP and DeformTM. Through these analyzes, it was found that the shape of how the bar is pulled causes a reduction of up to 100 MPa in residual stresses in the center of the bar, which represents an important factor in the study of the possible causes of the distortion. As well as factors speed and homogeneity of lubrication significantly altered the profile of residual stresses in the bar.

Decreased total antioxidant levels and increased oxidative stress in ...

African Journals Online (AJOL)

Background: Chronic hyperglycaemia in diabetes mellitus leads to increased lipid peroxidation in the body, followed by the development of chronic complications due to oxidative stress. Objective: The aim of this study was to compare total antioxidant (TAO) levels and oxidative stress in type 2 diabetes mellitus (T2DM) ...

Can stress in farm animals increase food safety risk?

Science.gov (United States)

Rostagno, Marcos H

2009-09-01

All farm animals will experience some level of stress during their lives. Stress reduces the fitness of an animal, which can be expressed through failure to achieve production performance standards, or through disease and death. Stress in farm animals can also have detrimental effects on the quality of food products. However, although a common assumption of a potential effect of stress on food safety exists, little is actually known about how this interaction may occur. The aim of this review was to examine the current knowledge of the potential impact of stress in farm animals on food safety risk. Colonization of farm animals by enteric pathogens such as Escherichia coli O157:H7, Salmonella, and Campylobacter, and their subsequent dissemination into the human food chain are a major public health and economic concern for the food industries. This review shows that there is increasing evidence to demonstrate that stress can have a significant deleterious effect on food safety through a variety of potential mechanisms. However, as the impact of stress is difficult to precisely determine, it is imperative that the issue receives more research attention in the interests of optimizing animal welfare and minimizing losses in product yield and quality, as well as to food safety risks to consumers. While there is some evidence linking stress with pathogen carriage and shedding in farm animals, the mechanisms underlying this effect have not been fully elucidated. Understanding when pathogen loads on the farm are the highest or when animals are most susceptible to infection will help identifying times when intervention strategies for pathogen control may be most effective, and consequently, increase the safety of food of animal origin.

β-cell dysfunction due to increased ER stress in a stem cell model of Wolfram syndrome.

Science.gov (United States)

Shang, Linshan; Hua, Haiqing; Foo, Kylie; Martinez, Hector; Watanabe, Kazuhisa; Zimmer, Matthew; Kahler, David J; Freeby, Matthew; Chung, Wendy; LeDuc, Charles; Goland, Robin; Leibel, Rudolph L; Egli, Dieter

2014-03-01

Wolfram syndrome is an autosomal recessive disorder caused by mutations in WFS1 and is characterized by insulin-dependent diabetes mellitus, optic atrophy, and deafness. To investigate the cause of β-cell failure, we used induced pluripotent stem cells to create insulin-producing cells from individuals with Wolfram syndrome. WFS1-deficient β-cells showed increased levels of endoplasmic reticulum (ER) stress molecules and decreased insulin content. Upon exposure to experimental ER stress, Wolfram β-cells showed impaired insulin processing and failed to increase insulin secretion in response to glucose and other secretagogues. Importantly, 4-phenyl butyric acid, a chemical protein folding and trafficking chaperone, restored normal insulin synthesis and the ability to upregulate insulin secretion. These studies show that ER stress plays a central role in β-cell failure in Wolfram syndrome and indicate that chemical chaperones might have therapeutic relevance under conditions of ER stress in Wolfram syndrome and other forms of diabetes.

Forgiveness, Stress, and Health: a 5-Week Dynamic Parallel Process Study.

Science.gov (United States)

Toussaint, Loren L; Shields, Grant S; Slavich, George M

2016-10-01

Psychological stress is a well-known risk factor for poor health, and recent research has suggested that the emotion-focused coping process of forgiveness may help mitigate these effects. To date, however, no studies have examined how levels of forgiveness, stress, and health fluctuate and interrelate over time. We addressed this issue by examining how forgiveness, stress, and mental and physical health symptoms change and relate to one another over 5 weeks. We hypothesized that increases in state levels of forgiveness would be associated with decreases in perceptions of stress, which would in turn be related to decreases in mental and physical health symptoms. A reverse effects model was also tested. We recruited a large, community-based sample of 332 young, middle-aged, and older adults (16-79 years old; M age  = 27.9). Each week for 5 weeks, participants reported on their levels of state forgiveness, perceived stress, and mental and physical health symptoms. Levels of forgiveness, stress, and mental and physical health symptoms each showed significant change and individual variability in change over time. As hypothesized, increases in forgiveness were associated with decreases in stress, which were in turn related to decreases in mental (but not physical) health symptoms (i.e., forgiveness → stress → health). The reverse effects model (i.e., health → stress → forgiveness) provided a relatively poorer fit. This study is the first to provide prospective, longitudinal evidence showing that greater forgiveness is associated with less stress and, in turn, better mental health. Strategies for cultivating forgiveness may thus have beneficial effects on stress and health.

Stress Fracture and Nonunion of Coronoid Process in a Gymnast

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T. Hetling

2016-01-01

Full Text Available Background. Gymnasts have high mechanical loading forces of up to 14 times body weight. Overuse lesions are typical in wrists and stress fractures in the olecranon, while isolated fractures of the coronoid process are uncommon. We present a case of retraumatized nonunion stress fracture of the ulnar coronoid process. Case Description. A 19-year-old gymnast presented with elbow pain after training. Imaging confirmed an old fracture of the coronoid process. We describe a 6-month multiphase return to competition rehabilitation program, which allowed him to compete pain-freely. Literature Review. Acute and overuse injuries in gymnasts are known but no nonunion of the coronoid process has been described before. Only one case of stress fracture of coronoid process in a gymnast was reported. Purpose and Clinical Relevance. We could successfully and conservatively return to sport a reactivated nonunion of a stress fracture of the coronoid process.

Stressful task increases drive for thinness and bulimia: a laboratory study.

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Sandra eSassaroli

2015-05-01

Full Text Available The scientific literature has suggested that stress undergirds the development of eating disorders (ED. Therefore, this study explored whether laboratory induced stress increases self-reported drive for thinness and bulimic symptoms measured via self-report. The relationship between control, perfectionism, stress, and cognition related to ED was examined using correlational methodology. 86 participants completed an experimental task using a personal computer. All individuals completed a battery of tests before and after the stressful task. Analyses showed a significant statistical increase in average scores on the drive for thinness and bulimia measured before and after a stressful task, and path analysis revealed two different cognitive models for the mechanism leading to drive for thinness and bulimia. These findings suggest that stress is an important factor in the development of the drive for thinness and bulimia.

Residual Stress Evaluation of Weld Inlay Process on Reactor Vessel Nozzles

Energy Technology Data Exchange (ETDEWEB)

Cho, Kihyun; Cho, Hong Seok [KEPCO KPS, Naju (Korea, Republic of)

2015-10-15

Weld overlay, weld inlay and stress improvement are mitigation technologies for butt joints. Weld overlay is done on pressurizer nozzles which are the highest potential locations occurring PWSCC due to high temperature in Korea. Reactor vessel nozzles are other big safety concerns for butt joints. Weld overlay and stress improvement should be so difficult to apply to those locations because space is too limited. Weld inlay should be one of the solutions. KEPCO KPS has developed laser welding system and process for reactor nozzles. Welding residual stress analysis is necessary for flaw evaluation. United States nuclear regulatory commission has calculated GTAW(Gas Tungsten Arc Welding) residual stress using ABAQUS. To confirm effectiveness of weld inlay process, welding residual stress analysis was performed. and difference between GTAW and LASER welding process was compared. Evaluation of weld inlay process using ANSYS and ABAQUS is performed. All of the both results are similar. The residual stress generated after weld inlay was on range of 450-500 MPa. Welding residual stresses are differently generated by GTAW and LASER welding. But regardless of welding process type, residual tensile stress is generated on inside surface.

Increased Adhesion of Listeria monocytogenes Strains to Abiotic Surfaces under Cold Stress

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Bo-Hyung Lee

2017-11-01

Full Text Available Food contamination by Listeria monocytogenes remains a major concern for some food processing chains, particularly for ready-to-eat foods, including processed foods. Bacterial adhesion on both biotic and abiotic surfaces is a source of contamination by pathogens that have become more tolerant or even persistent in food processing environments, including in the presence of adverse conditions such as cold and dehydration. The most distinct challenge that bacteria confront upon entry into food processing environments is the sudden downshift in temperature, and the resulting phenotypic effects are of interest. Crystal violet staining and the BioFilm Ring Test® were applied to assess the adhesion and biofilm formation of 22 listerial strains from different serogroups and origins under cold-stressed and cold-adapted conditions. The physicochemical properties of the bacterial surface were studied using the microbial adhesion to solvent technique. Scanning electron microscopy was performed to visualize cell morphology and biofilm structure. The results showed that adhesion to stainless-steel and polystyrene was increased by cold stress, whereas cold-adapted cells remained primarily in planktonic form. Bacterial cell surfaces exhibited electron-donating properties regardless of incubation temperature and became more hydrophilic as temperature decreased from 37 to 4°C. Moreover, the adhesion of cells grown at 4°C correlated with affinity for ethyl acetate, indicating the role of cell surface properties in adhesion.

Acute social stress increases biochemical and self report markers of stress without altering spatial learning in humans.

Science.gov (United States)

Klopp, Christine; Garcia, Carlos; Schulman, Allan H; Ward, Christopher P; Tartar, Jaime L

2012-01-01

Spatial learning is shown to be influenced by acute stress in both human and other animals. However, the intricacies of this relationship are unclear. Based on prior findings we hypothesized that compared to a control condition, a social stress condition would not affect spatial learning performance despite elevated biochemical markers of stress. The present study tested the effects of social stress in human males and females on a subsequent spatial learning task. Social stress induction consisted of evaluative stress (the Trier Social Stress Test, TSST) compared to a placebo social stress. Compared to the placebo condition, the TSST resulted in significantly elevated cortisol and alpha amylase levels at multiple time points following stress induction. In accord, cognitive appraisal measures also showed that participants in the TSST group experienced greater perceived stress compared to the placebo group. However, there were no group differences in performance on a spatial learning task. Our findings suggest that unlike physiological stress, social stress does not result in alterations in spatial learning in humans. It is possible that moderate social evaluative stress in humans works to prevent acute stress-mediated alterations in hippocampal learning processes..

Increase of resistance to cracking on stress relieving of hardened steel

International Nuclear Information System (INIS)

Velichko, V.V.; Zabil'skij, V.V.; Mikheev, G.M.

1995-01-01

Regularities of increase of resistance to cracking during stress relieving of hardened low-alloyed steels were studied, using complex of methods. Effect of carbon, stress concentrator radius, duration and temperature of stress relieving was studies in particular. Results of investigating kinetics of change of physicomechanical properties, hydrogen desorption from hardened specimens showed, that increase of resistance to cracking was caused by desorption from grain boundaries of diffusion-mobile hydrogen, formed during hardening. 18 refs., 8 figs

Residual stresses generated in F-522 steel by different machining processes

International Nuclear Information System (INIS)

Gracia-Navas, V.; Ferreres, I.; Maranon, J. A.; Garcia-Rosales, C.; Gil-Sevillano, J.

2005-01-01

Machining operations induce plastic deformation and heat generation in the near surface area of the machined part, giving rise to residual stresses. Depending on their magnitude and sign, these stresses can be detrimental or beneficial to the service life of the part. The final stress state depends on the machining process applied, as well as on the machining parameters. Therefore, the establishment of adequate machining guidelines requires the measurement of the residual stresses generated both at the surface and inside the material. in this work, the residual stresses generated in F-522 steel by two hard turning (conventional and laser assisted) and two grinding (production and finishing) processes were measured by X-ray diffraction. Additionally, depth profiles of the volume fraction of retained austenite, microstructure and nano hardness were obtained in order to correlate those results with the residual stress state obtained for each machining process. It has been observed that turning generates tensile stresses in the surface while grinding causes compressive stresses. Below the surface grinding generates weak tensile or nearly null stresses whereas turning generates strong compressive stresses. These results show that the optimum mechanising process (disregarding economical considerations) implies the combination of turning plus elimination of a small thickness by final grinding. (Author) 19 refs

Parental stress and air pollution increase childhood asthma in China.

Science.gov (United States)

Deng, Qihong; Deng, Linjing; Lu, Chan; Li, Yuguo; Norbäck, Dan

2018-08-01

Although air pollution and social stress may independently increase childhood asthma, little is known on their synergistic effect on asthma, particularly in China with high levels of stress and air pollution. To examine associations between exposure to a combination of parental stress and air pollution and asthma prevalence in children. We conducted a cohort study of 2406 preschool children in Changsha (2011-2012). A questionnaire was used to collect children's lifetime prevalence of asthma and their parental stress. Parental socioeconomic and psychosocial stresses were respectively defined in terms of housing size and difficulty concentrating. Children's exposure to ambient air pollutants was estimated using concentrations measured at monitoring stations. Associations between exposure to parental stress and air pollution and childhood asthma were estimated by multiple logistic regression models using odds ratio (OR) and 95% confidence interval (CI). Life time prevalence of asthma in preschool children (6.7%) was significantly associated with parental socioeconomic and psychosocial stresses with OR (95% CI) respectively 1.48 (1.02-2.16) and 1.64 (1.00-2.71). Asthma was also associated with exposure to air pollutants, with adjusted OR (95% CI) during prenatal and postnatal periods respectively 1.43 (1.10-1.86) and 1.35 (1.02-1.79) for SO 2 and 1.61 (1.19-2.18) and 1.76 (1.19-2.61) for NO 2 . The association with air pollution was significant only in children exposed to high parental stress, the association with parental stress was significant only in children exposed to high air pollution, and the association was the strongest in children exposed to a combination of parental stress and air pollution. Sensitivity analysis showed that the synergistic effects of parental stress and air pollution on childhood asthma were stronger in boys. Parental stress and air pollution were synergistically associated with increased childhood asthma, indicating a common biological

Good, bad and ugly word stress--fMRI evidence for foot structure driven processing of prosodic violations.

Science.gov (United States)

Domahs, Ulrike; Klein, Elise; Huber, Walter; Domahs, Frank

2013-06-01

Using a stress violation paradigm, we investigated whether metrical feet constrain the way prosodic patterns are processed and evaluated. Processing of correctly versus incorrectly stressed words was associated with activation in left posterior angular and retrosplenial cortex, indicating the recognition of an expected and familiar pattern, whereas the inverse contrast yielded enhanced bilateral activation in the superior temporal gyrus, reflecting higher costs in auditory (re-)analysis. More fine-grained analyses of severe versus mild stress violations revealed activations of the left superior temporal and left anterior angular gyrus whereas the opposite contrast led to frontal activations including Broca's area and its right-hemisphere homologue, suggesting that detection of mild violations lead to increased effort in working memory and deeper phonological processing. Our results provide first evidence that different incorrect stress patterns are processed in a qualitatively different way and that the underlying foot structure seems to determine potential stress positions in German words. Copyright © 2013 Elsevier Inc. All rights reserved.

Compensation processes of Aleppo pine (Pinus halepensis Mill.) to ozone exposure and drought stress

International Nuclear Information System (INIS)

Inclan, R.; Gimeno, B.S.; Dizengremel, P.; Sanchez, M.

2005-01-01

A long-term experiment was performed to study the effects of O 3 and drought-stress (DS) on Aleppo pine seedlings (Pinus halepensis Mill.) exposed in open-top chambers. Ozone reduced gas exchange rates, ribulose-1,5-biphosphate carboxylase/oxygenase activity (Rubisco), aboveground C and needle N concentrations and C/N ratio and Ca concentrations of the twigs under 3 mm (twigs Pd ), C/N ratio, twigs<3 Ca, plant growth, aerial biomass and increased N, twigs with a diameter above 3 mm P and Mg concentrations. The combined exposure to both stresses increased N concentrations of twigs<3 and roots and aboveground biomass K content and decreased root C, maximum daily assimilation rate and instantaneous water use efficiency. The sensitivity of Aleppo pine to both stresses is determined by plant internal resource allocation and compensation mechanisms to cope with stress. - Ozone and drought stress induce the activation of similar processes related to C and N metabolism

Increased amygdala reactivity following early life stress: a potential resilience enhancer role.

Science.gov (United States)

Yamamoto, Tetsuya; Toki, Shigeru; Siegle, Greg J; Takamura, Masahiro; Takaishi, Yoshiyuki; Yoshimura, Shinpei; Okada, Go; Matsumoto, Tomoya; Nakao, Takashi; Muranaka, Hiroyuki; Kaseda, Yumiko; Murakami, Tsuneji; Okamoto, Yasumasa; Yamawaki, Shigeto

2017-01-18

Amygdala hyper-reactivity is sometimes assumed to be a vulnerability factor that predates depression; however, in healthy people, who experience early life stress but do not become depressed, it may represent a resilience mechanism. We aimed to test these hypothesis examining whether increased amygdala activity in association with a history of early life stress (ELS) was negatively or positively associated with depressive symptoms and impact of negative life event stress in never-depressed adults. Twenty-four healthy participants completed an individually tailored negative mood induction task during functional magnetic resonance imaging (fMRI) assessment along with evaluation of ELS. Mood change and amygdala reactivity were increased in never-depressed participants who reported ELS compared to participants who reported no ELS. Yet, increased amygdala reactivity lowered effects of ELS on depressive symptoms and negative life events stress. Amygdala reactivity also had positive functional connectivity with the bilateral DLPFC, motor cortex and striatum in people with ELS during sad memory recall. Increased amygdala activity in those with ELS was associated with decreased symptoms and increased neural features, consistent with emotion regulation, suggesting that preservation of robust amygdala reactions may reflect a stress buffering or resilience enhancing factor against depression and negative stressful events.

The role of stressors and psychosocial variables in the stress process: a study of chronic caregiver stress.

Science.gov (United States)

Vedhara, K; Shanks, N; Anderson, S; Lightman, S

2000-01-01

An investigation was conducted 1) to examine the relative importance of stressor types (ie, daily hassles, caregiving-specific stressors, and life events) on the stress response, 2) to assess the stability of relationships between psychosocial variables and stress over a 6-month period, and 3) to explore how the nature and magnitude of the contributions made by stressors and psychosocial factors to the stress process varied according to the qualitative characteristics of the stress response (ie, anxiety, depression, and stress). Fifty spousal caregivers of patients with dementia were recruited and asked to participate in a detailed psychosocial evaluation at 3-month intervals; the evaluation involved measurement of stressor frequency, psychosocial variables, and indices of the stress response (ie, anxiety, depression, and stress). The data revealed that the effects of stressors and psychosocial factors on the stress response were considerable (accounting for 49-63% of the variance in stress response measures). Furthermore, there was some evidence of stability in the effects of the stressor and mediator variables on the stress response. Specifically, the contributions of life events and caregiver difficulties were largely consistent at both 3 and 6 months, and the psychosocial factor of "reactive coping and self-appraisal" influenced all three stress response indices at both 3 and 6 months. There is some evidence of stability in the effects of stressors and psychosocial variables on the stress process over a 6-month period. However, it would also seem that the nature of the stress process differs according to the qualitative characteristics of the stress response.

MINDFULNESS – MAY DIMINISH STRESS AND INCREASE ENERGY

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Andronicus TORP

2015-06-01

Full Text Available Mindfulness is increasingly being applied in companies as a means to increase, among others, employee wellbeing and energy, and in the same time to diminish stress. This paper argues that there seems to be scientific evidence showing that certain mindfulness techniques may diminish stress and increase energy, yet it seems that there is a period in the beginning of the mindfulness practice where the techniques have the opposite effects. These findings seem to be contradictory to past findings, which indicated that only two thirds of people practicing mindfulness techniques have positive effects from that practice. It may be that everybody can have positive effects from the practice of the mentioned techniques, just that some need to practice for a longer period before obtaining these positive effects. Further scientific studies seem to be needed in order to clarify the full spectrum of effects and consequences of practicing different mindfulness techniques, and just as important, if these effects are valid for everybody.

Acute Stress Modulates Feedback Processing in Men and Women: Differential Effects on the Feedback-Related Negativity and Theta and Beta Power

Science.gov (United States)

Banis, Stella; Geerligs, Linda; Lorist, Monicque M.

2014-01-01

Sex-specific prevalence rates in mental and physical disorders may be partly explained by sex differences in physiological stress responses. Neural networks that might be involved are those underlying feedback processing. Aim of the present EEG study was to investigate whether acute stress alters feedback processing, and whether stress effects differ between men and women. Male and female participants performed a gambling task, in a control and a stress condition. Stress was induced by exposing participants to a noise stressor. Brain activity was analyzed using both event-related potential and time-frequency analyses, measuring the feedback-related negativity (FRN) and feedback-related changes in theta and beta oscillatory power, respectively. While the FRN and feedback-related theta power were similarly affected by stress induction in both sexes, feedback-related beta power depended on the combination of stress induction condition and sex. FRN amplitude and theta power increases were smaller in the stress relative to the control condition in both sexes, demonstrating that acute noise stress impairs performance monitoring irrespective of sex. However, in the stress but not in the control condition, early lower beta-band power increases were larger for men than women, indicating that stress effects on feedback processing are partly sex-dependent. Our findings suggest that sex-specific effects on feedback processing may comprise a factor underlying sex-specific stress responses. PMID:24755943

Acute stress modulates feedback processing in men and women: differential effects on the feedback-related negativity and theta and beta power.

Directory of Open Access Journals (Sweden)

Stella Banis

Full Text Available Sex-specific prevalence rates in mental and physical disorders may be partly explained by sex differences in physiological stress responses. Neural networks that might be involved are those underlying feedback processing. Aim of the present EEG study was to investigate whether acute stress alters feedback processing, and whether stress effects differ between men and women. Male and female participants performed a gambling task, in a control and a stress condition. Stress was induced by exposing participants to a noise stressor. Brain activity was analyzed using both event-related potential and time-frequency analyses, measuring the feedback-related negativity (FRN and feedback-related changes in theta and beta oscillatory power, respectively. While the FRN and feedback-related theta power were similarly affected by stress induction in both sexes, feedback-related beta power depended on the combination of stress induction condition and sex. FRN amplitude and theta power increases were smaller in the stress relative to the control condition in both sexes, demonstrating that acute noise stress impairs performance monitoring irrespective of sex. However, in the stress but not in the control condition, early lower beta-band power increases were larger for men than women, indicating that stress effects on feedback processing are partly sex-dependent. Our findings suggest that sex-specific effects on feedback processing may comprise a factor underlying sex-specific stress responses.

Relationships among Career and Life Stress, Negative Career thoughts, and Career Decision State: A Cognitive Information Processing Perspective

Science.gov (United States)

Bullock-Yowell, Emily; Peterson, Gary W.; Reardon, Robert C.; Leierer, Stephen J.; Reed, Corey A.

2011-01-01

According to cognitive information processing theory, career thoughts mediate the relationship between career and life stress and the ensuing career decision state. Using a sample of 232 college students and structural equation modeling, this study found that an increase in career and life stress was associated with an increase in negative career…

Increased oxidative stress in patients with familial Mediterranean ...

African Journals Online (AJOL)

0.05) comparing to HC group. However, there were no statistically significant differences between the groups in terms of antioxidant vitamin levels. Conclusions: Our study demonstrated increased oxidative stress in patients with FMF during AP.

Determinants of job stress in chemical process industry: A factor analysis approach.

Science.gov (United States)

Menon, Balagopal G; Praveensal, C J; Madhu, G

2015-01-01

Job stress is one of the active research domains in industrial safety research. The job stress can result in accidents and health related issues in workers in chemical process industries. Hence it is important to measure the level of job stress in workers so as to mitigate the same to avoid the worker's safety related problems in the industries. The objective of this study is to determine the job stress factors in the chemical process industry in Kerala state, India. This study also aims to propose a comprehensive model and an instrument framework for measuring job stress levels in the chemical process industries in Kerala, India. The data is collected through a questionnaire survey conducted in chemical process industries in Kerala. The collected data out of 1197 surveys is subjected to principal component and confirmatory factor analysis to develop the job stress factor structure. The factor analysis revealed 8 factors that influence the job stress in process industries. It is also found that the job stress in employees is most influenced by role ambiguity and the least by work environment. The study has developed an instrument framework towards measuring job stress utilizing exploratory factor analysis and structural equation modeling.

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.

The effect of initial stress induced during the steel manufacturing process on the welding residual stress in multi-pass butt welding

Directory of Open Access Journals (Sweden)

Jeong-ung Park

2018-03-01

�MPa, while in case of thickness at 70 mm, it was 200 MPa. The increase in compressive residual stress is almost the same as the initial stress. However, if initial stress was tensile, there was no significant change in the maximum compression residual stress. Keywords: Initial stress, Thermal elastic plastic FE analysis, Welding residual stress, Manufacturing steel process, Multi-pass butt welding

Stress og aldring

DEFF Research Database (Denmark)

Jørgensen, Anders; Jørgensen, Martin Balslev; Poulsen, Henrik Enghusen

2012-01-01

Accumulating evidence supports the popular notion that psychological stress states may accelerate aging. Stress has been shown to influence cellular systems known to be involved in the aging process. Furthermore, stress is associated with an increased risk of various age-related medical disorders....... These effects are likely mediated by the secretion of stress hormones. In this short review we focus on biochemical and epidemiological evidence for a link between stress and aging.......Accumulating evidence supports the popular notion that psychological stress states may accelerate aging. Stress has been shown to influence cellular systems known to be involved in the aging process. Furthermore, stress is associated with an increased risk of various age-related medical disorders...

OXIDATIVE STRESS AND VASCULAR DAMAGE IN HYPOXIA PROCESSES. MALONDIALDEHYDE (MDA AS BIOMARKER FOR OXIDATIVE DAMAGE

Directory of Open Access Journals (Sweden)

Muñiz P

2014-05-01

Full Text Available Changes in the levels oxidative stress biomarkers are related with different diseases such as ischemia/reperfusion, cardiovascular, renal, aging, etc. One of these biomarkers is the malondialdehyde (MDA generated as resulted of the process of lipid peroxidation. This biomarker is increased under conditions of the oxidative stress. Their levels, have been frequently used to measure plasma oxidative damage to lipids by their atherogenic potential. Its half-life high and their reactivity allows it to act both inside and outside of cells and interaction with proteins and DNA involve their role in different pathophysiological processes. This paper presents an analysis of the use of MDA as a biomarker of oxidative stress and its implications associated pathologies such as cardiovascular diseases ago.

[Personality and occupation stress of workers in processing line in Guangzhou].

Science.gov (United States)

Lin, Qiu-hong; Zhang, Wei-sen; Zhou, Jing-dong; Fan, Yuan-yu; Liu, Li-fen; Li, Jian-lin; Liu, Wei-wei

2009-12-01

To study relationships between personality and occupational stress of workers in processing line in Guangzhou. 452 workers in processing line in Guangzhou were investigated by the Eysenck Personality Questionnaire (EPQ) and Occupational Stress Indicator (OSI). N scores and P scores of EPQ were positively correlated with the occupational stress and the poor physical fitness status (r value was 0.196, 0.128, 0.202, 0.218, respectively) (P stress coping ability(r value was -0.146, -0.140, respectively) (P stress coping ability (r = 0.176, P stress, the poor physical fitness status and the explanation to vicinity event (r value was -0.139, -0.140, -0.111, respectively) (P related to the occupational stress, the sense of job satisfaction and unhealthy mental reaction.

Living to the range limit: consumer isotopic variation increases with environmental stress

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Carl J. Reddin

2016-06-01

Full Text Available Background: Theoretically, each species’ ecological niche is phylogenetically-determined and expressed spatially as the species’ range. However, environmental stress gradients may directly or indirectly decrease individual performance, such that the precise process delimiting a species range may not be revealed simply by studying abundance patterns. In the intertidal habitat the vertical ranges of marine species may be constrained by their abilities to tolerate thermal and desiccation stress, which may act directly or indirectly, the latter by limiting the availability of preferred trophic resources. Therefore, we expected individuals at greater shore heights to show greater variation in diet alongside lower indices of physiological condition. Methods: We sampled the grazing gastropod Echinolittorina peruviana from the desert coastline of northern Chile at three shore heights, across eighteen regionally-representative shores. Stable isotope values (δ13C and δ15N were extracted from E. peruviana and its putative food resources to estimate Bayesian ellipse area, carbon and nitrogen ranges and diet. Individual physiological condition was tracked by muscle % C and % N. Results: There was an increase in isotopic variation at high shore levels, where E. peruviana’s preferred resource, tide-deposited particulate organic matter (POM, appeared to decrease in dietary contribution, and was expected to be less abundant. Both muscle % C and % N of individuals decreased with height on the shore. Discussion: Individuals at higher stress levels appear to be less discriminating in diet, likely because of abiotic forcing, which decreases both consumer mobility and the availability of a preferred resource. Abiotic stress might be expected to increase trophic variation in other selective dietary generalist species. Where this coincides with a lower physiological condition may be a direct factor in setting their range limit.

Cracking of GaN on sapphire from etch-process-induced nonuniformity in residual thermal stress

International Nuclear Information System (INIS)

Lacroix, Yves; Chung, Sung-Hoon; Sakai, Shiro

2001-01-01

An experiment was performed to explain the appearance of cracks along mesa structures during the processing of GaN device layers grown on sapphire substrates. Micro-Raman spectroscopy was used to measure the position-dependent stress in the GaN layer. We show evidence that the stress at the interface with the substrate may be larger along the mesa structures than that of the as-grown layer, and that this increase in stress can be enough to induce cracks along mesa structures during processing. We report on the formation of cracks that propagate guided by the nonuniformity of the stress induced by the formation of mesa structures in the GaN layer, independent of crystal direction. The understanding of cracking mechanisms has implications in GaN-based device structures that require heteroepitaxial growth of layers with different lattice size and thermal expansion coefficients. [copyright] 2001 American Institute of Physics

Endoplasmic reticulum stress is increased in adipose tissue of women with gestational diabetes.

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Stella Liong

Full Text Available Maternal obesity and gestational diabetes mellitus (GDM are two increasingly common and important obstetric complications that are associated with severe long-term health risks to mothers and babies. IL-1β, which is increased in obese and GDM pregnancies, plays an important role in the pathophysiology of these two pregnancy complications. In non-pregnant tissues, endoplasmic (ER stress is increased in diabetes and can induce IL-1β via inflammasome activation. The aim of this study was to determine whether ER stress is increased in omental adipose tissue of women with GDM, and if ER stress can also upregulate inflammasome-dependent secretion of IL-1β. ER stress markers IRE1α, GRP78 and XBP-1s were significantly increased in adipose tissue of obese compared to lean pregnant women. ER stress was also increased in adipose tissue of women with GDM compared to BMI-matched normal glucose tolerant (NGT women. Thapsigargin, an ER stress activator, induced upregulated secretion of mature IL-1α and IL-1β in human omental adipose tissue explants primed with bacterial endotoxin LPS, the viral dsRNA analogue poly(I:C or the pro-inflammatory cytokine TNF-α. Inhibition of capase-1 with Ac-YVAD-CHO resulted in decreased IL-1α and IL-1β secretion, whereas inhibition of pannexin-1 with carbenoxolone suppressed IL-1β secretion only. Treatment with anti-diabetic drugs metformin and glibenclamide also reduced IL-1α and IL-1β secretion in infection and cytokine-primed adipose tissue. In conclusion, this study has demonstrated ER stress to activate the inflammasome in pregnant adipose tissue. Therefore, increased ER stress may contribute towards the pathophysiology of obesity in pregnancy and GDM.

Stress history increases alcohol intake in relapse: relation to phosphodiesterase 10A.

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Logrip, Marian L; Zorrilla, Eric P

2012-09-01

Stressful experiences can result in elevated alcohol drinking, as exemplified in many individuals with post-traumatic stress disorder. However, how stress history, rather than acute stressors, influences alcohol intake remains uncertain. To model the protracted effects of past stress, male Wistar rats were subjected to light-cued footshock (stress history) or light cues alone (control) prior to acquisition of alcohol self-administration (1-hour sessions, fixed ratio 1-3, 100 µl of 10% v/v alcohol as reinforcer). Stress history did not alter mean alcohol intake during acquisition of self-administration, but it increased preference for the alcohol-paired lever over the inactive lever. Following an extinction period, rats with a history of stress exposure and low baseline alcohol intake showed a twofold elevation in alcohol self-administration, as compared with low-drinking rats with no stress history. Similar effects were not seen in rats self-administering 0.1% sucrose. Analysis of mRNA levels of phosphodiesterase 10A (PDE10A), a dual-specificity cyclic adenosine monophosphate and cyclic guanosine monophosphate hydrolyzing enzyme, showed that stress history increased Pde10a mRNA levels in the basolateral amygdala and, in low-drinking rats, the prelimbic prefrontal cortex (plPFC). Pde10a mRNA levels in the plPFC correlated directly with greater alcohol self-administration during the relapse-like phase, and greater BLA Pde10a mRNA levels correlated with increased ethanol preference after acquisition. The data demonstrate that stress history sensitizes otherwise low alcohol drinkers to consume more alcohol in a relapse-like situation and identify stress-induced neuroadaptations in amygdala and prefrontal cortical Pde10a expression as changes that may drive heightened alcohol intake and preference in susceptible individuals. © 2012 The Authors. Addiction Biology © 2012 Society for the Study of Addiction.

Stressful task increases drive for thinness and bulimia: a laboratory study

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Sassaroli, Sandra; Fiore, Francesca; Mezzaluna, Clarice; Ruggiero, Giovanni Maria

2015-01-01

The scientific literature has suggested that stress undergirds the development of eating disorders (ED). Therefore, this study explored whether laboratory induced stress increases self-reported drive for thinness and bulimic symptoms measured via self-report. The relationship between control, perfectionism, stress, and cognition related to ED was examined using correlational methodology. Eighty-six participants completed an experimental task using a personal computer (PC). All individuals com...

An experimental study of the job demand-control model with measures of heart rate variability and salivary alpha-amylase: Evidence of increased stress responses to increased break autonomy.

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O'Donnell, Emma; Landolt, Kathleen; Hazi, Agnes; Dragano, Nico; Wright, Bradley J

2015-01-01

We assessed in an experimental design whether the stress response towards a work task was moderated by the autonomy to choose a break during the assigned time to complete the task. This setting is defined in accordance with the theoretical framework of the job-demand-control (JDC) model of work related stress. The findings from naturalistic investigations of a stress-buffering effect of autonomy (or 'buffer hypothesis') are equivocal and the experimental evidence is limited, especially with relation to physiological indices of stress. Our objective was to investigate if increased autonomy in a particular domain (break time control) was related with adaptive physiology using objective physiological markers of stress; heart rate variability (HRV) and salivary alpha amylase (sAA). We used a within-subject design and the 60 female participants were randomly assigned to an autonomy (free timing of break) and standard conditions (fixed timing of break) of a word processing task in a simulated office environment in a random order. Participants reported increased perceptions of autonomy, no difference in demand and performed worse in the task in the break-time autonomy versus the standard condition. The results revealed support for the manipulation of increased autonomy, but in the opposing direction. Increased autonomy was related with dysregulated physiological reactivity, synonymous with typical increased stress responses. Potentially, our findings may indicate that autonomy is not necessary a resource but could become an additional stressor when it adds additional complexity while the amount of work (demands) remains unchanged. Further, our findings underscore the need to collect objective physiological evidence of stress to supplement self-reported information. Self-report biases may partially explain the inconsistent findings with the buffer hypothesis. Copyright © 2014 Elsevier Ltd. All rights reserved.

ER stress affects processing of MHC class I-associated peptides

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Meloche Sylvain

2009-02-01

Full Text Available Abstract Background Viral infection and neoplastic transformation trigger endoplasmic reticulum (ER stress. Thus, a large proportion of the cells that must be recognized by the immune system are stressed cells. Cells respond to ER stress by launching the unfolded protein response (UPR. The UPR regulates the two key processes that control major histocompatibility complex class I (MHC I-peptide presentation: protein synthesis and degradation. We therefore asked whether and how the UPR impinges on MHC I-peptide presentation. Results We evaluated the impact of the UPR on global MHC I expression and on presentation of the H2Kb-associated SIINFEKL peptide. EL4 cells stably transfected with vectors coding hen egg lysozyme (HEL-SIINFEKL protein variants were stressed with palmitate or exposed to glucose deprivation. UPR decreased surface expression of MHC I but did not affect MHC I mRNA level nor the total amount of intracellular MHC I proteins. Impaired MHC I-peptide presentation was due mainly to reduced supply of peptides owing to an inhibition of overall protein synthesis. Consequently, generation of H2Kb-SIINFEKL complexes was curtailed during ER stress, illustrating how generation of MHC I peptide ligands is tightly coupled to ongoing protein synthesis. Notably, the UPR-induced decline of MHC I-peptide presentation was more severe when the protein source of peptides was localized in the cytosol than in the ER. This difference was not due to changes in the translation rates of the precursor proteins but to increased stability of the cytosolic protein during ER stress. Conclusion Our results demonstrate that ER stress impairs MHC I-peptide presentation, and that it differentially regulates expression of ER- vs. cytosol-derived peptides. Furthermore, this work illustrates how ER stress, a typical feature of infected and malignant cells, can impinge on cues for adaptive immune recognition.

Process-induced viscoelastic stress in composite laminates

International Nuclear Information System (INIS)

Stango, R.J.

1985-01-01

In recent years, considerable interest has developed in evaluating the stress response of composite laminates which is associated with cooling the material system from the cure temperature to room temperature. This research examines the fundamental nature of time-dependent residual-thermal stresses in composite laminates which are caused by the extreme temperature reduction encountered during the fabrication process. Viscoelastic stress in finite-width, symmetric composite laminates is examined on the basis of a formulation that employs an incremental hereditary integral approach in conjunction with a quasi-three dimensional finite element analysis. A consistent methodology is developed and employed for the characterization of lamina material properties. Special attention is given to the time-dependent stress response at ply-interface locations near the free-edge. In addition, the influence of cooling path on stress history is examined. Recently published material property data for graphite-epoxy lamina is employed in the analysis. Results of the investigation generally indicate that nominal differences between the thermoelastic and viscoelastic solutions are obtained. Slight changes of the final stress state are observed to result when different cooling paths are selected for the temperature history. The methodology employed is demonstrated to result in an accurate, efficient, and consistent approach for the viscoelastic analysis of advanced composite laminates

Respiratory sinus arrhythmia during worry forecasts stress-related increases in psychological distress.

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Gouin, Jean-Philippe; Deschênes, Sonya S; Dugas, Michel J

2014-09-01

Respiratory sinus arrhythmia (RSA) has been conceptualized as an index of emotion regulation abilities. Although resting RSA has been associated with both concurrent and prospective affective responses to stress, the impact of RSA reactivity on emotional responses to stress is inconsistent across studies. The type of emotional stimuli used to elicit these phasic RSA responses may influence the adaptive value of RSA reactivity. We propose that RSA reactivity to a personally relevant worry-based stressor might forecast future affective responses to stress. To evaluate whether resting RSA and RSA reactivity to worry inductions predict stress-related increases in psychological distress, an academic stress model was used to prospectively examine changes in psychological distress from the well-defined low- and high-stress periods. During the low-stress period, 76 participants completed self-report mood measures and had their RSA assessed during a resting baseline, free worry period and worry catastrophizing interview. Participants completed another mood assessment during the high-stress period. Results indicated that baseline psychological distress predicted larger decreases in RSA during the worry inductions. Lower resting RSA and greater RSA suppression to the worry inductions at baseline prospectively predicted larger increases in psychological distress from the low- to high-stress period, even after accounting for the impact of baseline distress on RSA. These results provide further evidence that RSA may represent a unique index of emotion regulation abilities in times of stress.

Processing of syllable stress is functionally different from phoneme processing and does not profit from literacy acquisition

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Ulrike eSchild

2014-06-01

Full Text Available Speech is characterized by phonemes and prosody. Neurocognitive evidence supports the separate processing of each type of information. Therefore, one might suggest individual development of both pathways. In this study, we examine literacy acquisition in middle childhood. Children become aware of the phonemes in speech at that time and refine phoneme processing when they acquire an alphabetic writing system. We test whether an enhanced sensitivity to phonemes in middle childhood extends to other aspects of the speech signal, such as prosody. To investigate prosodic processing, we used stress priming. Spoken stressed and unstressed syllables (primes preceded spoken German words with stress on the first syllable (targets. We orthogonally varied stress overlap and phoneme overlap between the primes and onsets of the targets. Lexical decisions and Event-Related Potentials (ERPs for the targets were obtained for pre-reading preschoolers, reading pupils and adults. The behavioral and ERP results were largely comparable across all groups. The fastest responses were observed when the first syllable of the target word shared stress and phonemes with the preceding prime. ERP stress priming and ERP phoneme priming started 200 ms after the target word onset. Bilateral ERP stress priming was characterized by enhanced ERP amplitudes for stress overlap. Left-lateralized ERP phoneme priming replicates previously observed reduced ERP amplitudes for phoneme overlap. Groups differed in the strength of the behavioral phoneme priming and in the late ERP phoneme priming effect. The present results show that enhanced phonological processing in middle childhood is restricted to phonemes and does not extend to prosody. These results are indicative of two parallel processing systems for phonemes and prosody that might follow different developmental trajectories in middle childhood as a function of alphabetic literacy.

Stress-induced alterations in estradiol sensitivity increase risk for obesity in women.

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Michopoulos, Vasiliki

2016-11-01

The prevalence of obesity in the United States continues to rise, increasing individual vulnerability to an array of adverse health outcomes. One factor that has been implicated causally in the increased accumulation of fat and excess food intake is the activity of the limbic-hypothalamic-pituitary-adrenal (LHPA) axis in the face of relentless stressor exposure. However, translational and clinical research continues to understudy the effects sex and gonadal hormones and LHPA axis dysfunction in the etiology of obesity even though women continue to be at greater risk than men for stress-induced disorders, including depression, emotional feeding and obesity. The current review will emphasize the need for sex-specific evaluation of the relationship between stress exposure and LHPA axis activity on individual risk for obesity by summarizing data generated by animal models currently being leveraged to determine the etiology of stress-induced alterations in feeding behavior and metabolism. There exists a clear lack of translational models that have been used to study female-specific risk. One translational model of psychosocial stress exposure that has proven fruitful in elucidating potential mechanisms by which females are at increased risk for stress-induced adverse health outcomes is that of social subordination in socially housed female macaque monkeys. Data from subordinate female monkeys suggest that increased risk for emotional eating and the development of obesity in females may be due to LHPA axis-induced changes in the behavioral and physiological sensitivity of estradiol. The lack in understanding of the mechanisms underlying these alterations necessitate the need to account for the effects of sex and gonadal hormones in the rationale, design, implementation, analysis and interpretation of results in our studies of stress axis function in obesity. Doing so may lead to the identification of novel therapeutic targets with which to combat stress-induced obesity

Stress-induced resistance to the fear memory labilization/reconsolidation process. Involvement of the basolateral amygdala complex.

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Espejo, Pablo Javier; Ortiz, Vanesa; Martijena, Irene Delia; Molina, Victor Alejandro

2016-10-01

Consolidated memories can enter into a labile state after reactivation followed by a restabilization process defined as reconsolidation. This process can be interfered with Midazolam (MDZ), a positive allosteric modulator of the GABA-A receptor. The present study has evaluated the influence of prior stress on MDZ's interfering effect. We also assessed the influence of both systemic and intra-basolateral amygdala (BLA) infusion of d-cycloserine (DCS), a partial agonist of the NMDA receptors, on the MDZ effect in previously stressed rats. Furthermore, we analyzed the effect of stress on the expression of Zif-268 and the GluN2B sites, two molecular markers of the labilization/reconsolidation process, following reactivation. The results revealed that prior stress resulted into a memory trace that was insensitive to the MDZ impairing effect. Both systemic and intra-BLA DCS administration previous to reactivation restored MDZ's disruptive effect on memory reconsolidation in stressed animals. Further, reactivation enhanced Zif-268 expression in the BLA in control unstressed rats, whereas no elevation was observed in stressed animals. In agreement with the behavioral findings, DCS restored the increased level of Zif-268 expression in the BLA in stressed animals. Moreover, memory reactivation in unstressed animals elevated GluN2B expression in the BLA, thus suggesting that this effect is involved in memory destabilization, whereas stressed animals did not reveal any changes. These findings are consistent with resistance to the MDZ effect in these rats, indicating that stress exposure prevents the onset of destabilization following reactivation. In summary, prior stress limited both the occurrence of the reactivation-induced destabilization and restabilization. Copyright © 2016 Elsevier Ltd. All rights reserved.

Molecular Mechanisms of Stress-Induced Increases in Fear Memory Consolidation within the Amygdala.

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Aubry, Antonio V; Serrano, Peter A; Burghardt, Nesha S

2016-01-01

Stress can significantly impact brain function and increase the risk for developing various psychiatric disorders. Many of the brain regions that are implicated in psychiatric disorders and are vulnerable to the effects of stress are also involved in mediating emotional learning. Emotional learning has been a subject of intense investigation for the past 30 years, with the vast majority of studies focusing on the amygdala and its role in associative fear learning. However, the mechanisms by which stress affects the amygdala and amygdala-dependent fear memories remain unclear. Here we review the literature on the enhancing effects of acute and chronic stress on the acquisition and/or consolidation of a fear memory, as measured by auditory Pavlovian fear conditioning, and discuss potential mechanisms by which these changes occur in the amygdala. We hypothesize that stress-mediated activation of glucocorticoid receptors (GR) and norepinephrine release within the amygdala leads to the mobilization of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors to the synapse, which underlies stress-induced increases in fear memory. We discuss the implications of this hypothesis for evaluating the effects of stress on extinction and for developing treatments for anxiety disorders. Understanding how stress-induced changes in glucocorticoid and norepinephrine signaling might converge to affect emotional learning by increasing the trafficking of AMPA receptors and enhancing amygdala excitability is a promising area for future research.

Molecular Mechanisms of Stress-Induced Increases in Fear Memory Consolidation Within the Amygdala

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Antonio Aubry

2016-10-01

Full Text Available Stress can significantly impact brain function and increase the risk for developing various psychiatric disorders. Many of the brain regions that are implicated in psychiatric disorders and are vulnerable to the effects of stress are also involved in mediating emotional learning. Emotional learning has been a subject of intense investigation for the past 30 years, with the vast majority of studies focusing on the amygdala and its role in associative fear learning. However, the mechanisms by which stress affects the amygdala and amygdala-dependent fear memories remain unclear. Here we review the literature on the enhancing effects of acute and chronic stress on the acquisition and/or consolidation of a fear memory, as measured by auditory Pavlovian fear conditioning, and discuss potential mechanisms by which these changes occur in the amygdala. We hypothesize that stress-mediated activation of glucocorticoid receptors (GR and norepinephrine release within the amygdala leads to the mobilization of AMPA receptors to the synapse, which underlies stress-induced increases in fear memory. We discuss the implications of this hypothesis for evaluating the effects of stress on extinction and for developing treatments for anxiety disorders. Understanding how stress-induced changes in glucocorticoid and norepinephrine signaling might converge to affect emotional learning by increasing the trafficking of AMPA receptors and enhancing amygdala excitability is a promising area for future research.

Nondestructive control of residual stresses during welding and recharge processes

International Nuclear Information System (INIS)

Suarez, J.C.; Fernandez, L.M.; Cruz, C.; Merino, F.; Aragon, B.

1993-01-01

In this work, the stress state of material during welding and recharge processes is controlled with the help of Barkhausen effect. The changes, occurred in the longitudinal and transversal stress profile are show during deposition of welding rings. It is proved that the stress state of the base-material depends on the amount of recharge layers, deposited on it

Stress associated with caregiving: an examination of the stress process model among Kenyan Luo elders.

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Ice, Gillian H; Sadruddin, Aalyia F A; Vagedes, Amy; Yogo, Jaja; Juma, Elizabeth

2012-06-01

Globally, a growing number of grandparents are caring for their grandchildren. The impact and burden associated with increases in custodial grandparenting, however, may differ by culture. In the United States, the caregiving role has been shown to be a significant source of stress for older adults. In cultures in which grandparents are more commonly involved in the care of young children, however, increasing caregiving roles may not be viewed as stressful. This study examines the impact of caregiving on perceived and physiological measures of stress among 640 Luo elders (60+) in western Kenya, where high HIV prevalence among younger-to-middle aged adults has led to a heavy burden of orphan care. Perceived stress levels were measured using the Luo Perceived Stress Scale (LPSS). Salivary cortisol and casual blood pressure were used as biomarkers of stress. Results were analyzed using random mixed effects models. Overall this study showed that caregivers have higher levels of perceived stress than non-caregivers. For women, household composition, including the number of orphans and adults in the homestead impacted perceived stress. Among men, those who perceived caregiving as burdensome had higher perceived stress. Despite the association between caregiving and perceived stress, there was a minimal relationship between caregiving and the two biomarkers of stress. This may be because caregiving is superimposed onto other stressors and therefore has a minimal physiological impact. These results highlight the importance of local context in determining the impact of the caregiving role on older adult well-being. Copyright © 2012 Elsevier Ltd. All rights reserved.

[Emotional stress-induced Shanghuo syndrome increases disease susceptibility].

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Zhu, Si-Rui; Luo, Xiang; Li, Yi-Fang; Hiroshi, Kurihara; He, Rong-Rong

2018-04-01

Shanghuo(excessive internal heat) is a special organic state based on the concept of traditional Chinese medicine(TCM), commonly known as the abnormal heating syndrome of body in folks. With the acceleration of modern life rhythm and the increase of the social competition pressure, emotional stress has become an important cause for the spread of Shanghuo symptoms. What's more, Shanghuo can impact the body physiological functions to cause the onset, recurrence and progression of common diseases, harming the health of the body. According to the long-term research findings, the author found that Shanghuo referred to the imbalance of multiple physiological functions, such as nerve, immunity and metabolism, caused by emotional stress. "Shanghuo" is not a disease itself, but it can increase the susceptibility to a variety of diseases. This study reviewed the traditional medicine theory and the modern medical studies, and explored the relevance and correlation mechanisms between the Shanghuo symptoms and disease susceptibility, so as to provide a reference to improve the state of sub-health and prevent or treat modern diseases. Copyright© by the Chinese Pharmaceutical Association.

Decreased total antioxidant levels and increased oxidative stress in ...

African Journals Online (AJOL)

21–25 ... Decreased total antioxidant levels and increased oxidative stress in South ... antioxidant-rich diet and lifestyle changes in T2DM patients would help to avert the .... glycation of proteins and the formation of advanced glycosylation.

Increased risk taking in relation to chronic stress in young adults

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Smarandita eCeccato

2016-01-01

Full Text Available Chronic stress is a public health problem that affects a significant part of the population. While the physiological damage it causes is under ongoing scrutiny, its behavioral effects have been overlooked. This is one of the first studies to examine the relation between chronic stress and decision-making, using a standard lottery paradigm. We measured learning-independent risk taking in the gain domain through binary choices between financially incentivized lotteries. We then measured self-reported chronic stress with the Trier Inventory for the Assessment of Chronic Stress (TICS. We additionally collected hair samples in a subsample of volunteers, in order to quantify chronic cortisol exposure. We discovered a significant, positive correlation between self-reported chronic stress and risk taking that is stronger for women than for men. This confirms part of the findings in acute stress research that show a connection between higher stress and increased risk taking. However, unlike the biologically-based results from acute stress research, we did not identify a significant relation between hair cortisol and behavior. In line with previous literature, we found a clear gender difference in risk taking and self-reports: women generally take less risk and report slightly higher stress levels than men. We conclude that perceived chronic stress can impact behavior in risky situations.

Automatic affective-motivational regulation processes underlying supportive dyadic coping: the role of increased implicit positive attitudes toward communal goals in response to a stressed relationship partner.

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Koranyi, Nicolas; Hilpert, Peter; Job, Veronika; Bodenmann, Guy

2017-09-01

We examined the implicit affective mechanisms underlying provision of support in intimate dyads. Specifically, we hypothesized that in individuals with high relationship satisfaction, the perception that one's partner is stressed leads to increased implicit positive attitudes toward communal goals. In turn, this change in implicit attitudes facilitates supportive behavior. In two studies, we induced partner stress by instructing participants to either recall a situation where their partner was highly stressed (Study 1; N = 47 university students) or imagine a specific stressful event (excessive workload; Study 2; N = 85 university students). Subsequently, implicit attitudes toward communal goals were assessed with an Implicit Association Test. In both studies, we found that among participants with high relationship satisfaction partner stress increases preferences for communal goals. In addition, implicit preferences for communal goals predicted stronger inclinations to engage in supportive dyadic coping (Study 2). The current findings provide important insights into the implicit cognitive-affective mechanics of dyadic coping. Moreover, they can explain how people manage to avoid experiencing motivational conflicts between partner-oriented and self-oriented goals in situations characterized by high partner stress.

Prazosin Prevents Increased Anxiety Behavior That Occurs in Response to Stress During Alcohol Deprivations.

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Rasmussen, Dennis D; Kincaid, Carrie L; Froehlich, Janice C

2017-01-01

Stress-induced anxiety is a risk factor for relapse to alcohol drinking. The aim of this study was to test the hypothesis that the central nervous system (CNS)-active α 1 -adrenergic receptor antagonist, prazosin, would block the stress-induced increase in anxiety that occurs during alcohol deprivations. Selectively bred male alcohol-preferring (P) rats were given three cycles of 5 days of ad libitum voluntary alcohol drinking interrupted by 2 days of alcohol deprivation, with or without 1 h of restraint stress 4 h after the start of each of the first two alcohol deprivation cycles. Prazosin (1.0 or 1.5 mg/kg, IP) or vehicle was administered before each restraint stress. Anxiety-like behavior during alcohol deprivation following the third 5-day cycle of alcohol drinking (7 days after the most recent restraint stress ± prazosin treatment) was measured by performance in an elevated plus-maze and in social approach/avoidance testing. Rats that received constant alcohol access, or alcohol access and deprivations without stress or prazosin treatments in the first two alcohol deprivations did not exhibit augmented anxiety-like behavior during the third deprivation. In contrast, rats that had been stressed during the first two alcohol deprivations exhibited increased anxiety-like behavior (compared with control rats) in both anxiety tests during the third deprivation. Prazosin given before stresses in the first two cycles of alcohol withdrawal prevented increased anxiety-like behavior during the third alcohol deprivation. Prazosin treatment before stresses experienced during alcohol deprivations may prevent the increased anxiety during subsequent deprivation/abstinence that is a risk factor for relapse to alcohol drinking. Administration of prazosin before stresses during repetitive alcohol deprivations in male alcohol-preferring (P) rats prevents increased anxiety during a subsequent deprivation without further prazosin treatment. Prazosin treatment during repeated

Stress system changes associated with marijuana dependence may increase craving for alcohol and cocaine

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Fox, Helen C.; Tuit, Keri L.; Sinha, Rajita

2013-01-01

Objective To date, little research exists defining bio-behavioral adaptations associated with both marijuana abuse and risk of craving and relapse to other drugs of abuse during early abstinence. Method Fifty-nine treatment-seeking individuals dependent on alcohol and cocaine were recruited. Thirty of these individuals were also marijuana (MJ) dependent; 29 were not. Twenty-six socially drinking healthy controls were also recruited. All participants were exposed to three 5-min guided imagery conditions (stress, alcohol/cocaine cue and relaxing), presented randomly, one per day across three consecutive days. Measures of craving, anxiety, heart rate, blood pressure, plasma adrenocorticotrophic hormone and cortisol were collected at baseline and subsequent recovery time points. Results The MJ-dependent group showed increased basal anxiety ratings and cardiovascular output alongside enhanced alcohol craving and cocaine craving, and dampened cardiovascular response to stress and cue. They also demonstrated elevated cue-induced anxiety and stress-induced cortisol and adrenocorticotrophic hormone levels, which were not observed in the non-MJ-dependent group or controls. Cue-related alcohol craving and anxiety were both predictive of a shorter number of days to marijuana relapse following discharge from inpatient treatment. Conclusions Findings provide some support for drug cross-sensitization in terms of motivational processes associated with stress-related and cue-related craving and relapse. PMID:23280514

Isolation stress and chronic mild stress induced immobility in the defensive burying behavior and a transient increased ethanol intake in Wistar rats.

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Vázquez-León, Priscila; Martínez-Mota, Lucía; Quevedo-Corona, Lucía; Miranda-Páez, Abraham

2017-09-01

Stress can be experienced with or without adverse effects, of which anxiety and depression are two of the most important due to the frequent comorbidity with alcohol abuse in humans. Historically, stress has been considered a cause of drug use, particularly alcohol abuse due to its anxiolytic effects. In the present work we exposed male Wistar rats to two different stress conditions: single housing (social isolation, SI), and chronic mild stress (CMS). We compared both stressed groups to group-housed rats and rats without CMS (GH) to allow the determination of a clear behavioral response profile related to their respective endocrine stress response and alcohol intake pattern. We found that SI and CMS, to a greater extent, induced short-lasting increased sucrose consumption, a transient increase in serum corticosterone level, high latency/immobility, and low burying behavior in the defensive burying behavior (DBB) test, and a transient increase in alcohol intake. Thus, the main conclusion was that stress caused by both SI and CMS induced immobility in the DBB test and, subsequently, induced a transient increased voluntary ethanol intake in Wistar rats with a free-choice home-cage drinking paradigm. Copyright © 2017 Elsevier Inc. All rights reserved.

Transgenic tobacco plants constitutively expressing peanut BTF3 exhibit increased growth and tolerance to abiotic stresses.

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Pruthvi, V; Rama, N; Parvathi, M S; Nataraja, K N

2017-05-01

Abiotic stresses limit crop growth and productivity worldwide. Cellular tolerance, an important abiotic stress adaptive trait, involves coordinated activities of multiple proteins linked to signalling cascades, transcriptional regulation and other diverse processes. Basal transcriptional machinery is considered to be critical for maintaining transcription under stressful conditions. From this context, discovery of novel basal transcription regulators from stress adapted crops like peanut would be useful for improving tolerance of sensitive plant types. In this study, we prospected a basal transcription factor, BTF3 from peanut (Arachis hypogaea L) and studied its relevance in stress acclimation by over expression in tobacco. AhBTF3 was induced under PEG-, NaCl-, and methyl viologen-induced stresses in peanut. The constitutive expression of AhBTF3 in tobacco increased plant growth under non stress condition. The transgenic plants exhibited superior phenotype compared to wild type under mannitol- and NaCl-induced stresses at seedling level. The enhanced cellular tolerance of transgenic plants was evidenced by higher cell membrane stability, reactive oxygen species (ROS) scavenging activity, seedling survival and vigour than wild type. The transgenic lines showed better in vitro regeneration capacity on growth media supplemented with NaCl than wild type. Superior phenotype of transgenic plants under osmotic and salinity stresses seems to be due to constitutive activation of genes of multiple pathways linked to growth and stress adaptation. The study demonstrated that AhBTF3 is a positive regulator of growth and stress acclimation and hence can be considered as a potential candidate gene for crop improvement towards stress adaptation. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

Increased Dicarbonyl Stress as a Novel Mechanism of Multi-Organ Failure in Critical Illness

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Bas C. T. van Bussel

2017-02-01

Full Text Available Molecular pathological pathways leading to multi-organ failure in critical illness are progressively being unravelled. However, attempts to modulate these pathways have not yet improved the clinical outcome. Therefore, new targetable mechanisms should be investigated. We hypothesize that increased dicarbonyl stress is such a mechanism. Dicarbonyl stress is the accumulation of dicarbonyl metabolites (i.e., methylglyoxal, glyoxal, and 3-deoxyglucosone that damages intracellular proteins, modifies extracellular matrix proteins, and alters plasma proteins. Increased dicarbonyl stress has been shown to impair the renal, cardiovascular, and central nervous system function, and possibly also the hepatic and respiratory function. In addition to hyperglycaemia, hypoxia and inflammation can cause increased dicarbonyl stress, and these conditions are prevalent in critical illness. Hypoxia and inflammation have been shown to drive the rapid intracellular accumulation of reactive dicarbonyls, i.e., through reduced glyoxalase-1 activity, which is the key enzyme in the dicarbonyl detoxification enzyme system. In critical illness, hypoxia and inflammation, with or without hyperglycaemia, could thus increase dicarbonyl stress in a way that might contribute to multi-organ failure. Thus, we hypothesize that increased dicarbonyl stress in critical illness, such as sepsis and major trauma, contributes to the development of multi-organ failure. This mechanism has the potential for new therapeutic intervention in critical care.

Reward anticipation modulates the effect of stress-related increases in cortisol on episodic memory.

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Quent, Jörn A; McCullough, Andrew M; Sazma, Matt; Wolf, Oliver T; Yonelinas, Andrew P

2018-01-01

When acute stress is experienced shortly after an event is encoded into memory, this can slow the forgetting of the study event, which is thought to reflect the effect of cortisol on consolidation. In addition, when events are encoded under conditions of high reward they tend to be remembered better than those encoded under non-rewarding conditions, and these effects are thought to reflect the operation of the dopaminergic reward system. Although both modulatory systems are believed to impact the medial temporal lobe regions critical for episodic memory, the manner, and even the extent, to which these two systems interact is currently unknown. To address this question in the current study, participants encoded words under reward or non-reward conditions, then one half of the participants were stressed using the social evaluation cold pressor task and the other half completed a non-stress control task. After a two-hour delay, all participants received a free recall and recognition memory test. There were no significant effects of stress or reward on overall memory performance. However, for the non-reward items, increases in stress-related cortisol in stressed participants were related to increases in recall and increases in recollection-based recognition responses. In contrast, for the reward items, increases in stress-related cortisol were not related to increases in memory performance. The results indicate that the stress and the reward systems interact in the way they impact episodic memory. The results are consistent with tag and capture models in the sense that cortisol reactivity can only affect non-reward items because plasticity-related products are already provided by reward anticipation. Copyright © 2017 Elsevier Inc. All rights reserved.

Processing of word stress related acoustic information: A multi-feature MMN study.

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Honbolygó, Ferenc; Kolozsvári, Orsolya; Csépe, Valéria

2017-08-01

In the present study, we investigated the processing of word stress related acoustic features in a word context. In a passive oddball multi-feature MMN experiment, we presented a disyllabic pseudo-word with two acoustically similar syllables as standard stimulus, and five contrasting deviants that differed from the standard in that they were either stressed on the first syllable or contained a vowel change. Stress was realized by an increase of f0, intensity, vowel duration or consonant duration. The vowel change was used to investigate if phonemic and prosodic changes elicit different MMN components. As a control condition, we presented non-speech counterparts of the speech stimuli. Results showed all but one feature (non-speech intensity deviant) eliciting the MMN component, which was larger for speech compared to non-speech stimuli. Two other components showed stimulus related effects: the N350 and the LDN (Late Discriminative Negativity). The N350 appeared to the vowel duration and consonant duration deviants, specifically to features related to the temporal characteristics of stimuli, while the LDN was present for all features, and it was larger for speech than for non-speech stimuli. We also found that the f0 and consonant duration features elicited a larger MMN than other features. These results suggest that stress as a phonological feature is processed based on long-term representations, and listeners show a specific sensitivity to segmental and suprasegmental cues signaling the prosodic boundaries of words. These findings support a two-stage model in the perception of stress and phoneme related acoustical information. Copyright © 2017 Elsevier B.V. All rights reserved.

X-ray microbeam measurements of long-range internal stresses in commercial-purity aluminum processed by multiple passes of equal-channel angular pressing

International Nuclear Information System (INIS)

Phan, Thien Q.; Lee, I-Fang; Levine, Lyle E.; Tischler, Jonathan Z.; Huang, Yi; Fox, Alan G.; Langdon, Terence G.; Kassner, Michael E.

2014-01-01

X-ray microbeam diffraction was used to measure long-range internal stresses (LRISs) in the grain/subgrain interiors of commercial-purity aluminum processed by equal-channel angular pressing for up to eight passes. The LRIS values at +4.9° off the axial (pressing) direction show only a slight increase with increasing numbers of passes. The normalized stress remains approximately constant at ∼0.10 of the flow stress

Increase in oxidative stress levels following welding fume inhalation: a controlled human exposure study.

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Graczyk, Halshka; Lewinski, Nastassja; Zhao, Jiayuan; Sauvain, Jean-Jacques; Suarez, Guillaume; Wild, Pascal; Danuser, Brigitta; Riediker, Michael

2016-06-10

Tungsten inert gas (TIG) welding represents one of the most widely used metal joining processes in industry. It has been shown to generate a large majority of particles at the nanoscale and to have low mass emission rates when compared to other types of welding. Despite evidence that TIG fume particles may produce reactive oxygen species (ROS), limited data is available for the time course changes of particle-associated oxidative stress in exposed TIG welders. Twenty non-smoking male welding apprentices were exposed to TIG welding fumes for 60 min under controlled, well-ventilated settings. Exhaled breathe condensate (EBC), blood and urine were collected before exposure, immediately after exposure, 1 h and 3 h post exposure. Volunteers participated in a control day to account for oxidative stress fluctuations due to circadian rhythm. Biological liquids were assessed for total reducing capacity, hydrogen peroxide (H2O2), malondialdehyde (MDA), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations at each time point. A linear mixed model was used to assess within day and between day differences. Significant increases in the measured biomarkers were found at 3 h post exposure. At 3 h post exposure, we found a 24 % increase in plasma-H2O2 concentrations ([95%CI: 4 % to 46 %], p = 0.01); a 91 % increase in urinary-H2O2 ([2 % to 258 %], p = 0.04); a 14 % increase in plasma-8-OHdG ([0 % to 31 %], p = 0.049); and a 45 % increase in urinary-8-OHdG ([3 % to 105 %], p = 0.03). Doubling particle number concentration (PNC) exposure was associated with a 22 % increase of plasma-8-OHdG at 3 h post exposure (p = 0.01). A 60-min exposure to TIG welding fume in a controlled, well-ventilated setting induced acute oxidative stress at 3 h post exposure in healthy, non-smoking apprentice welders not chronically exposed to welding fumes. As mass concentration of TIG welding fume particles is very low when compared to other types of welding, it is

[Increase in number of operations for stress urinary incontinence

NARCIS (Netherlands)

Vierhout, M.E.

2005-01-01

Since the introduction of the minimally invasive tension-free vaginal tape (TVT) the number of operations performed for treatment of stress urinary incontinence has increased dramatically from over 1600 in 1999 to more than 4200 in 2003. Both gynaecologists and urologists now perform more TVTs and

A dyadic analysis of stress processes in Latinas with breast cancer and their family caregivers.

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Segrin, Chris; Badger, Terry A; Sikorskii, Alla; Crane, Tracy E; Pace, Thaddeus W W

2018-03-01

Breast cancer diagnosis and treatment negatively affect quality of life for survivors and their family caregivers. The stress process model has been useful for describing the cascade of social and psychological experiences that culminate in degraded quality of life for both survivors and their family caregivers. This study is designed to test theoretically specified predictors of negative psychosocial outcomes in a dyadic context. Participants were 230 dyads composed of Latinas recently diagnosed with breast cancer and their primary family caregiver, who completed measures of socioeconomic status, stress, family conflict, depression, and anxiety. Data were analyzed following the Actor-Partner Interdependence Mediation Model in structural equation modeling. For both survivors and caregivers, there were significant direct and indirect actor effects (through family conflict) of perceived stress on depression and anxiety. Several indirect partner effects were also evident in this sample. Specifically, caregivers' stress was predictive of survivors' depression and anxiety through survivors' increased perceptions of family conflict. As predicted by the stress process model, stress and family conflict were predictive of psychological distress in breast cancer survivors and their family caregivers. Significant partner effects in the Actor-Partner Interdependence Mediation Model suggest that there are some dyadic influences, particularly from caregivers' stress to survivors' perceptions of exacerbated family conflict. These findings show how strained family relationships can aggravate the well-being of cancer survivors and their family caregivers through this challenging experience. Copyright © 2017 John Wiley & Sons, Ltd.

Effect of Mindfulness Based Stress Reduction (MBSR in Increasing Pain Tolerance and Improving the Mental Health of Injured Athletes

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Warhel Asim Mohammed

2018-05-01

Full Text Available Literature indicates that injured athletes face both physical and psychological distress after they have been injured. In this study, a Mindfulness Based Stress Reduction (MBSR was utilised as an intervention for use during the period of recovery with injured athletes and, to the best of our knowledge, this is the first study using MBSR as an intervention for this purpose.Objective: The aim of this research was to investigate the role of MBSR practise in reducing the perception of pain and decreasing anxiety/stress, as well as increasing pain tolerance and mindfulness. An additional aim was to increase positive mood and decrease negative mood in injured athletes.Methods: The participants comprised of twenty athletes (male = 14; female = 6; age range = 21–36 years who had severe injuries, preventing their participation in sport for more than 3 months. Prior to their injury, the participants had trained regularly with their University teams and participated in official university championships. Both groups followed their normal physiotherapy treatment, but in addition, the intervention group practised mindfulness meditation for 8 weeks (one 90-min session/week. A Cold Pressor Test (CPT was used to assess pain tolerance. In contrast, the perception of pain was measured using a Visual Analogue Scale. Other measurements used were the Mindful Attention Awareness Scale (MAAS, Depression Anxiety and Stress Scale (DASS, and Profile of Mood States (POMS.Results: Our results demonstrated an increase in pain tolerance for the intervention group and an increase in mindful awareness for injured athletes. Moreover, our findings observed a promising change in positive mood for both groups. Regarding the Stress/Anxiety scores, our findings showed a notable decrease across sessions; however, no significant changes were observed in other main and interaction effects in both groups.Conclusion: Injured athletes can benefit from using mindfulness as part of the

The multitasking framework: the effects of increasing workload on acute psychobiological stress reactivity.

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Wetherell, Mark A; Carter, Kirsty

2014-04-01

A variety of techniques exist for eliciting acute psychological stress in the laboratory; however, they vary in terms of their ease of use, reliability to elicit consistent responses and the extent to which they represent the stressors encountered in everyday life. There is, therefore, a need to develop simple laboratory techniques that reliably elicit psychobiological stress reactivity that are representative of the types of stressors encountered in everyday life. The multitasking framework is a performance-based, cognitively demanding stressor, representative of environments where individuals are required to attend and respond to several different stimuli simultaneously with varying levels of workload. Psychological (mood and perceived workload) and physiological (heart rate and blood pressure) stress reactivity was observed in response to a 15-min period of multitasking at different levels of workload intensity in a sample of 20 healthy participants. Multitasking stress elicited increases in heart rate and blood pressure, and increased workload intensity elicited dose-response increases in levels of perceived workload and mood. As individuals rarely attend to single tasks in real life, the multitasking framework provides an alternative technique for modelling acute stress and workload in the laboratory. Copyright © 2013 John Wiley & Sons, Ltd.

Oral contraceptive therapy increases oxidative stress in pre-menopausal women

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Jui Tung Chen

2012-01-01

Conclusions: The use of OCT may increase oxidative stress levels, independent of traditional cardiovascular risk factors, in pre-menopausal women, providing new insights to the primary prevention of vascular complications in these subjects.

Potassium and zinc increase tolerance to salt stress in wheat (Triticum aestivum L.).

Science.gov (United States)

Jan, Amin Ullah; Hadi, Fazal; Midrarullah; Nawaz, Muhammad Asif; Rahman, Khaista

2017-07-01

Potassium and zinc are essential elements in plant growth and metabolism and plays a vital role in salt stress tolerance. To investigate the physiological mechanism of salt stress tolerance, a pot experiment was conducted. Potassium and zinc significantly minimize the oxidative stress and increase root, shoot and spike length in wheat varieties. Fresh and dry biomass were significantly increased by potassium followed by zinc as compared to control C. The photosynthetic pigment and osmolyte regulator (proline, total phenolic, and total carbohydrate) were significantly enhanced by potassium and zinc. Salt stress increases MDA content in wheat varieties while potassium and zinc counteract the adverse effect of salinity and significantly increased membrane stability index. Salt stress decreases the activities of antioxidant enzymes (superoxide dismutase, catalase and ascorbate peroxidase) while the exogenous application of potassium and zinc significantly enhanced the activities of these enzymes. A significant positive correlation was found of spike length with proline (R 2  = 0.966 ∗∗∗ ), phenolic (R 2  = 0.741 ∗ ) and chlorophyll (R 2  = 0.853 ∗∗ ). The MDA content showed significant negative correlation (R 2  = 0.983 ∗∗∗ ) with MSI. It is concluded that potassium and zinc reduced toxic effect of salinity while its combine application showed synergetic effect and significantly enhanced salt tolerance. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Stress corrosion cracking of stainless steel under deaerated high-temperature water. Influence of cold work and processing orientation

International Nuclear Information System (INIS)

Terachi, Takumi; Yamada, Takuyo; Chiba, Goro; Arioka, Koji

2006-01-01

The influence of cold work and processing orientation on the propagation of stress corrosion cracking (SCC) of stainless steel under hydrogenated high-temperature water was examined. It was shown that (1) the crack growth rates increased with heaviness of cold work, and (2) processing orientation affected crack growth rate with cracking direction. Crack growth rates showed anisotropy of T-L>>T-S>L-S, with T-S and L-S branches representing high shear stress direction. Geometric deformation of crystal grains due to cold work caused the anisotropy and shear stress also assisted the SCC propagation. (3) The step intervals of slip like patterns observed on intergranular facets increased cold work. (4) Nano-indentation hardness of the crack tip together with EBSD measurement indicated that the change of hardness due to crack propagation was less than 5% cold-work, even though the distance from the crack tip was 10μm. (author)

Acute stress-induced cortisol elevations mediate reward system activity during subconscious processing of sexual stimuli.

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Oei, Nicole Y L; Both, Stephanie; van Heemst, Diana; van der Grond, Jeroen

2014-01-01

Stress is thought to alter motivational processes by increasing dopamine (DA) secretion in the brain's "reward system", and its key region, the nucleus accumbens (NAcc). However, stress studies using functional magnetic resonance imaging (fMRI), mainly found evidence for stress-induced decreases in NAcc responsiveness toward reward cues. Results from both animal and human PET studies indicate that the stress hormone cortisol may be crucial in the interaction between stress and dopaminergic actions. In the present study we therefore investigated whether cortisol mediated the effect of stress on DA-related responses to -subliminal-presentation of reward cues using the Trier Social Stress Test (TSST), which is known to reliably enhance cortisol levels. Young healthy males (n = 37) were randomly assigned to the TSST or control condition. After stress induction, brain activation was assessed using fMRI during a backward-masking paradigm in which potentially rewarding (sexual), emotionally negative and neutral stimuli were presented subliminally, masked by pictures of inanimate objects. A region of interest analysis showed that stress decreased activation in the NAcc in response to masked sexual cues (voxel-corrected, pcortisol levels were related to stronger NAcc activation, showing that cortisol acted as a suppressor variable in the negative relation between stress and NAcc activation. The present findings indicate that cortisol is crucially involved in the relation between stress and the responsiveness of the reward system. Although generally stress decreases activation in the NAcc in response to rewarding stimuli, high stress-induced cortisol levels suppress this relation, and are associated with stronger NAcc activation. Individuals with a high cortisol response to stress might on one hand be protected against reductions in reward sensitivity, which has been linked to anhedonia and depression, but they may ultimately be more vulnerable to increased reward

Bicuspid aortic valves are associated with increased wall and turbulence shear stress levels compared to trileaflet aortic valves.

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Saikrishnan, Neelakantan; Mirabella, Lucia; Yoganathan, Ajit P

2015-06-01

Congenital bicuspid aortic valves (BAVs) are associated with accelerated disease progression, such as leaflet calcification and ascending aorta dilatation. Although common underlying genetic factors have been implicated in accelerated disease in BAV patients, several studies have suggested that altered hemodynamics also play a role in this disease process. The present study compares turbulence and wall shear stress (WSS) measurements between various BAV and trileaflet aortic valve (TAV) models to provide information for mechanobiological models of BAV disease. BAV and TAV models were constructed from excised porcine aortic valves to simulate parametric variations in BAV stenosis, hemodynamics and geometry. Particle image velocimetry experiments were conducted at physiological pressure conditions to characterize velocity fields in the ascending aorta. The velocity fields were post-processed to calculate turbulence, viscous and wall shear stresses in the ascending aorta. Stenosed BAV models showed the presence of eccentric systolic jets, causing increased WSS. Lower cardiac output resulted in a narrower jet, lower turbulence and lower viscous shear stress (VSS). The specific severe stenosis BAV model studied here showed reduced WSS due to reduction in non-fused leaflet mobility. Dilation of the aorta did not affect any turbulence or VSS, but reduced the WSS. In comparison with BAVs, TAVs have similar VSS values, but much smaller WSS and turbulence levels. These increased turbulence  and WSS levels in BAVs may play a key role in amplifying the biological responses of the ascending aorta wall and valvular leaflets, and support the hemodynamic underpinnings of BAV disease processes.

Increased gluconeogenesis in rats exposed to hyper-G stress

International Nuclear Information System (INIS)

Daligcon, B.C.; Oyama, J.; Hannak, K.

1985-01-01

The role of gluconeogenesis on the increase in plasma glucose and liver glycogen of rats exposed to hyper-G (radial acceleration) stress was determined. Overnight-fasted, male Sprague-Dawley rats (250-300 g) were injected i.p. with uniformly labeled 14 C lactate, alanine, or glycerol (5 μCi/rat) and immediately exposed to 3.1 G for 0.25, 0.50, and 1.0 hr. 14 C incorporation of the labeled substrates into plasma glucose and liver glycogen was measured and compared to noncentrifuged control rats injected in a similar manner. Significant increases in 14 C incorporation of all three labeled substrates into plasma glucose were observed in centrifuged rats at all exposure periods; 14 C incorporation into liver glycogen was significantly increased only at 0.50 and 1.0 hr. The i.p. administration (5 mg/100-g body wt) of 5-methoxyindole-2-carboxylic acid, a potent gluconeogenesis inhibitor, prior to centrifugation blocked the increase in plasma glucose and liver glycogen during the first hour of centrifugation. The increase in plasma glucose and liver glycogen was also abolished in adrenodemedullated rats exposed to centrifugation for 1.0 hr. Propranolol, a beta-adrenergic blocker, suppressed the increase in plasma glucose of rats exposed to centrifugation for 0.25 hr. From the results of this study, it is concluded that the initial, rapid rise in plasma glucose as well as the increase in liver glycogen of rats exposed to hyper-G stress can be attributed to an increased rate of gluconeogenesis, and that epinephrine plays a dominant role during the early stages of exposure to centrifugation. 11 references, 3 tables

Prefrontal cortex executive processes affected by stress in health and disease.

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Girotti, Milena; Adler, Samantha M; Bulin, Sarah E; Fucich, Elizabeth A; Paredes, Denisse; Morilak, David A

2017-07-06

Prefrontal cortical executive functions comprise a number of cognitive capabilities necessary for goal directed behavior and adaptation to a changing environment. Executive dysfunction that leads to maladaptive behavior and is a symptom of psychiatric pathology can be instigated or exacerbated by stress. In this review we survey research addressing the impact of stress on executive function, with specific focus on working memory, attention, response inhibition, and cognitive flexibility. We then consider the neurochemical pathways underlying these cognitive capabilities and, where known, how stress alters them. Finally, we review work exploring potential pharmacological and non-pharmacological approaches that can ameliorate deficits in executive function. Both preclinical and clinical literature indicates that chronic stress negatively affects executive function. Although some of the circuitry and neurochemical processes underlying executive function have been characterized, a great deal is still unknown regarding how stress affects these processes. Additional work focusing on this question is needed in order to make progress on developing interventions that ameliorate executive dysfunction. Published by Elsevier Inc.

Deleting the 14-3-3 protein Bmh1 extends life span in Saccharomyces cerevisiae by increasing stress response.

Science.gov (United States)

Wang, Chen; Skinner, Craig; Easlon, Erin; Lin, Su-Ju

2009-12-01

Enhanced stress response has been suggested to promote longevity in many species. Calorie restriction (CR) and conserved nutrient-sensing target of rapamycin (TOR) and protein kinase A (PKA) pathways have also been suggested to extend life span by increasing stress response, which protects cells from age-dependent accumulation of oxidative damages. Here we show that deleting the yeast 14-3-3 protein, Bmh1, extends chronological life span (CLS) by activating the stress response. 14-3-3 proteins are highly conserved chaperone-like proteins that play important roles in many cellular processes. bmh1Delta-induced heat resistance and CLS extension require the general stress-response transcription factors Msn2, Msn4, and Rim15. The bmh1Delta mutant also displays a decreased reactive oxygen species level and increased heat-shock-element-driven transcription activity. We also show that BMH1 genetically interacts with CR and conserved nutrient-sensing TOR- and PKA-signaling pathways to regulate life span. Interestingly, the level of phosphorylated Ser238 on Bmh1 increases during chronological aging, which is delayed by CR or by reduced TOR activities. In addition, we demonstrate that PKA can directly phosphorylate Ser238 on Bmh1. The status of Bmh1 phosphorylation is therefore likely to play important roles in life-span regulation. Together, our studies suggest that phosphorylated Bmh1 may cause inhibitory effects on downstream longevity factors, including stress-response proteins. Deleting Bmh1 may eliminate the inhibitory effects of Bmh1 on these longevity factors and therefore extends life span.

Glucocorticoid receptor number predicts increase in amygdala activity after severe stress

NARCIS (Netherlands)

Geuze, Elbert; van Wingen, Guido A.; van Zuiden, Mirjam; Rademaker, Arthur R.; Vermetten, Eric; Kavelaars, Annemieke; Fernández, Guillén; Heijnen, Cobi J.

2012-01-01

Introduction: Individuals who are exposed to a traumatic event are at increased risk of developing psychiatric disorders such as posttraumatic stress disorder (PTSD). Studies have shown that increased amygdala activity is frequently found in patients with PTSD. In addition, pre-trauma glucocorticoid

Sleep spindles predict stress-related increases in sleep disturbances

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Thien Thanh eDang-Vu

2015-02-01

Full Text Available Background and Aim: Predisposing factors place certain individuals at higher risk for insomnia, especially in the presence of precipitating conditions such as stressful life events. Sleep spindles have been shown to play an important role in the preservation of sleep continuity. Lower spindle density might thus constitute an objective predisposing factor for sleep reactivity to stress. The aim of this study was therefore to evaluate the relationship between baseline sleep spindle density and the prospective change in insomnia symptoms in response to a standardized academic stressor. Methods: 12 healthy students had a polysomnography (PSG recording during a period of lower stress at the beginning of the academic semester, along with an assessment of insomnia complaints using the Insomnia Severity Index (ISI. They completed a second ISI assessment at the end of the semester, a period coinciding with the week prior to final examinations and thus higher stress. Spindle density, amplitude, duration and frequency, as well as sigma power were computed from C4-O2 electroencephalography (EEG derivation during stages N2-N3 of non-rapid-eye-movement (NREM sleep, across the whole night and for each NREM sleep period. To test for the relationship between spindle density and changes in insomnia symptoms in response to academic stress, spindle measurements at baseline were correlated with changes in ISI across the academic semester.Results: Spindle density (as well as spindle amplitude and sigma power, particularly during the first NREM sleep period, negatively correlated with changes in ISI (p < 0.05. Conclusion: Lower spindle activity, especially at the beginning of the night, prospectively predicted larger increases in insomnia symptoms in response to stress. This result indicates that individual differences in sleep spindle activity contribute to the differential vulnerability to sleep disturbances in the face of precipitating factors.

Dietary-induced binge eating increases prefrontal cortex neural activation to restraint stress and increases binge food consumption following chronic guanfacine.

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Bello, Nicholas T; Walters, Amy L; Verpeut, Jessica L; Caverly, Jonathan

2014-10-01

Binge eating is a prominent feature of bulimia nervosa and binge eating disorder. Stress or perceived stress is an often-cited reason for binge eating. One notion is that the neural pathways that overlap with stress reactivity and feeding behavior are altered by recurrent binge eating. Using young adult female rats in a dietary-induced binge eating model (30 min access to binge food with or without 24-h calorie restriction, twice a week, for 6 weeks) we measured the neural activation by c-Fos immunoreactivity to the binge food (vegetable shortening mixed with 10% sucrose) in bingeing and non-bingeing animals under acute stress (immobilization; 1 h) or no stress conditions. There was an increase in the number of immunopositive cells in the dorsal medial prefrontal cortex (mPFC) in stressed animals previously exposed to the binge eating feeding schedules. Because attention deficit hyperactive disorder (ADHD) medications target the mPFC and have some efficacy at reducing binge eating in clinical populations, we examined whether chronic (2 weeks; via IP osmotic mini-pumps) treatment with a selective alpha-2A adrenergic agonist (0.5 mg/kg/day), guanfacine, would reduce binge-like eating. In the binge group with only scheduled access to binge food (30 min; twice a week; 8 weeks), guanfacine increased total calories consumed during the 30-min access period from the 2-week pre-treatment baseline and increased binge food consumption compared with saline-treated animals. These experiments suggest that mPFC is differentially activated in response to an immobilization stress in animals under different dietary conditions and chronic guanfacine, at the dose tested, was ineffective at reducing binge-like eating. Copyright © 2014 Elsevier Inc. All rights reserved.

Academic stress and personality interact to increase the neural response to high-calorie food cues.

Science.gov (United States)

Neseliler, Selin; Tannenbaum, Beth; Zacchia, Maria; Larcher, Kevin; Coulter, Kirsty; Lamarche, Marie; Marliss, Errol B; Pruessner, Jens; Dagher, Alain

2017-09-01

Psychosocial stress is associated with an increased intake of palatable foods and weight gain in stress-reactive individuals. Personality traits have been shown to predict stress-reactivity. However, it is not known if personality traits influence brain activity in regions implicated in appetite control during psychosocial stress. The current study assessed whether Gray's Behavioural Inhibition System (BIS) scale, a measure of stress-reactivity, was related to the activity of brain regions implicated in appetite control during a stressful period. Twenty-two undergraduate students participated in a functional magnetic resonance imaging (fMRI) experiment once during a non-exam period and once during final exams in a counter-balanced order. In the scanner, they viewed food and scenery pictures. In the exam compared with the non-exam condition, BIS scores related to increased perceived stress and correlated with increased blood-oxygen-level dependent (BOLD) response to high-calorie food images in regions implicated in food reward and subjective value, such as the ventromedial prefrontal cortex, (vmPFC) and the amygdala. BIS scores negatively related to the functional connectivity between the vmPFC and the dorsolateral prefrontal cortex. The results demonstrate that the BIS trait influences stress reactivity. This is observed both as an increased activity in brain regions implicated in computing the value of food cues and decreased connectivity of these regions to prefrontal regions implicated in self-control. This suggests that the effects of real life stress on appetitive brain function and self-control is modulated by a personality trait. This may help to explain why stressful periods can lead to overeating in vulnerable individuals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Analysis of residual stress state in sheet metal parts processed by single point incremental forming

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Maaß, F.; Gies, S.; Dobecki, M.; Brömmelhoff, K.; Tekkaya, A. E.; Reimers, W.

2018-05-01

The mechanical properties of formed metal components are highly affected by the prevailing residual stress state. A selective induction of residual compressive stresses in the component, can improve the product properties such as the fatigue strength. By means of single point incremental forming (SPIF), the residual stress state can be influenced by adjusting the process parameters during the manufacturing process. To achieve a fundamental understanding of the residual stress formation caused by the SPIF process, a valid numerical process model is essential. Within the scope of this paper the significance of kinematic hardening effects on the determined residual stress state is presented based on numerical simulations. The effect of the unclamping step after the manufacturing process is also analyzed. An average deviation of the residual stress amplitudes in the clamped and unclamped condition of 18 % reveals, that the unclamping step needs to be considered to reach a high numerical prediction quality.

Prenatal stress may increase vulnerability to life events comparison with the effects of prenatal dexamethasone

DEFF Research Database (Denmark)

Hougaard, Karin; Andersen, Maibritt B; Kjaer, Sanna L

2005-01-01

naïve at the time of ASR testing, whereas the other had been through blood sampling for assessment of the hormonal stress response to restraint, 3 months previously. Both prenatal CMS and dexamethasone increased ASR in the offspring compared to controls, but only in prenatally stressed offspring......Prenatal stress has been associated with a variety of alterations in the offspring. The presented observations suggest that rather than causing changes in the offspring per se, prenatal stress may increase the organism's vulnerability to aversive life events. Offspring of rat dams stressed...... of the acoustic startle response. Further, a single aversive life event showed capable of changing the reactivity of prenatally stressed offspring, whereas offspring of dams going through a less stressful gestation was largely unaffected by this event. This suggests that circumstances dating back to the very...

Analytical study of residual stress improvement method, delta-T process for small-diameter pipe

International Nuclear Information System (INIS)

Tsuruki, Masaki; Aoike, Satoru; Okido, Shinobu; Fukuda, Yuka; Oritani, Naohiko

2012-01-01

In order to prevent initiation of stress corrosion cracking (SCC) at the inner surface of the butt-weld region of a small-diameter pipe, a residual stress improvement process called delta-T process has been developed. During delta-T process, the outer surface of pipe is heated by an external device and the inner surface is rapidly cooled by flashing water. The large thermal stress due to temperature difference between outer and inner surface could improve tensile stress to compressive one at inner surface. In this paper, the thermal elasto-plastic finite element analysis (FEA) was conducted to clarify the mechanism of delta-T process for piping system with 50A schedule 80 in nominal pipe size. The FEA results showed good agreements with experimentally measurements of temperature and residual stress in delta-T process. In addition, the management criterion to verify the application of delta-T process to piping system by measurement of temperature at outer surface of pipe was discussed by various parametric numerical analyses. (author)

How Accumulated Real Life Stress Experience and Cognitive Speed Interact on Decision-Making Processes

Directory of Open Access Journals (Sweden)

Eva Friedel

2017-06-01

Full Text Available Rationale: Advances in neurocomputational modeling suggest that valuation systems for goal-directed (deliberative on one side, and habitual (automatic decision-making on the other side may rely on distinct computational strategies for reinforcement learning, namely model-free vs. model-based learning. As a key theoretical difference, the model-based system strongly demands cognitive functions to plan actions prospectively based on an internal cognitive model of the environment, whereas valuation in the model-free system relies on rather simple learning rules from operant conditioning to retrospectively associate actions with their outcomes and is thus cognitively less demanding. Acute stress reactivity is known to impair model-based but not model-free choice behavior, with higher working memory capacity protecting the model-based system from acute stress. However, it is not clear which impact accumulated real life stress has on model-free and model-based decision systems and how this influence interacts with cognitive abilities.Methods: We used a sequential decision-making task distinguishing relative contributions of both learning strategies to choice behavior, the Social Readjustment Rating Scale questionnaire to assess accumulated real life stress, and the Digit Symbol Substitution Test to test cognitive speed in 95 healthy subjects.Results: Individuals reporting high stress exposure who had low cognitive speed showed reduced model-based but increased model-free behavioral control. In contrast, subjects exposed to accumulated real life stress with high cognitive speed displayed increased model-based performance but reduced model-free control.Conclusion: These findings suggest that accumulated real life stress exposure can enhance reliance on cognitive speed for model-based computations, which may ultimately protect the model-based system from the detrimental influences of accumulated real life stress. The combination of accumulated real life

How Accumulated Real Life Stress Experience and Cognitive Speed Interact on Decision-Making Processes.

Science.gov (United States)

Friedel, Eva; Sebold, Miriam; Kuitunen-Paul, Sören; Nebe, Stephan; Veer, Ilya M; Zimmermann, Ulrich S; Schlagenhauf, Florian; Smolka, Michael N; Rapp, Michael; Walter, Henrik; Heinz, Andreas

2017-01-01

Rationale: Advances in neurocomputational modeling suggest that valuation systems for goal-directed (deliberative) on one side, and habitual (automatic) decision-making on the other side may rely on distinct computational strategies for reinforcement learning, namely model-free vs. model-based learning. As a key theoretical difference, the model-based system strongly demands cognitive functions to plan actions prospectively based on an internal cognitive model of the environment, whereas valuation in the model-free system relies on rather simple learning rules from operant conditioning to retrospectively associate actions with their outcomes and is thus cognitively less demanding. Acute stress reactivity is known to impair model-based but not model-free choice behavior, with higher working memory capacity protecting the model-based system from acute stress. However, it is not clear which impact accumulated real life stress has on model-free and model-based decision systems and how this influence interacts with cognitive abilities. Methods: We used a sequential decision-making task distinguishing relative contributions of both learning strategies to choice behavior, the Social Readjustment Rating Scale questionnaire to assess accumulated real life stress, and the Digit Symbol Substitution Test to test cognitive speed in 95 healthy subjects. Results: Individuals reporting high stress exposure who had low cognitive speed showed reduced model-based but increased model-free behavioral control. In contrast, subjects exposed to accumulated real life stress with high cognitive speed displayed increased model-based performance but reduced model-free control. Conclusion: These findings suggest that accumulated real life stress exposure can enhance reliance on cognitive speed for model-based computations, which may ultimately protect the model-based system from the detrimental influences of accumulated real life stress. The combination of accumulated real life stress exposure

Effect of processing conditions and methods on residual stress in CeO2 buffer layers and YBCO superconducting films

International Nuclear Information System (INIS)

Xiong Jie; Qin Wenfeng; Cui Xumei; Tao Bowan; Tang Jinlong; Li Yanrong

2006-01-01

CeO 2 layers have been fabricated by pulsed laser deposition (PLD) technique on (1 1 0 2) sapphire substrate. Microstructure of CeO 2 layers is characterized by X-ray diffraction as functions of substrate temperature. The effects of the substrate temperature on the residual stress have been studied. The results show that residual stress in CeO 2 film decreased with increasing substrate temperature, not the same development tendency as that of thermal stress. This means that the thermal stress is only a fraction of the residual stress. Moreover, YBCO superconducting films were prepared by direct current (DC) sputtering and pulsed laser deposition (PLD) technique. The residual stress and thermal stress of both YBCO films were measured. PLD processing apparently generated higher intrinsic compressive stresses in comparison to DC sputtering

Investigation of Performance and Residual Stress Generation of AlSi10Mg Processed by Selective Laser Melting

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Lianfeng Wang

2018-01-01

Full Text Available During the selective laser melting (SLM process, the scanned layers are subjected to rapid thermal cycles. By working on the mechanical properties, residual stress, and microstructure, the high-temperature gradients can have significant effect on the proper functioning and the structural integrity of built parts. This work presents a comprehensive study on the scanning path type and preheating temperature for AlSi10Mg alloy during SLM. According to the results, SLM AlSi10Mg parts fabricated in chessboard scanning strategy have higher mechanical properties or at least comparable to the parts fabricated in uniformity scanning strategy. In the SLM processing, the residual stress in different parts of the specimen varies with temperature gradient, and the residual stress at the edge of the specimen is obviously larger than that at the center. Under the chessboard scanning and preheating temperature 160°C, the residual stress in each direction of the specimens reaches the minimum. Under different forming processes, the morphology of the microstructure is obviously different. With the increase of preheating temperature, the molten pool in the side surface is obviously elongated and highly unevenly distributed. From the coupling relationship between the residual stress and microstructure, it can be found that the microstructure of top surface is affected by residual stresses σx and σy. But the side surface is mainly governed by residual stress σy; moreover, the greater the residual stress, the more obvious the grain tilt. In the XY and XZ surfaces, the scanning strategy has little influence on the tilt angle of the grain. But, the tilt angle and morphology of the microstructure are obviously affected by the preheating temperature. The results show that the residual stresses can effectively change the properties of the materials under the combined influence of scanning strategy and preheating temperature.

Biosynthesis of vitamin C by yeast leads to increased stress resistance.

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Paola Branduardi

Full Text Available BACKGROUND: In industrial large scale bio-reactions micro-organisms are generally exposed to a variety of environmental stresses, which might be detrimental for growth and productivity. Reactive oxygen species (ROS play a key role among the common stress factors--directly--through incomplete reduction of O(2 during respiration, or indirectly--caused by other stressing factors. Vitamin C or L-ascorbic acid acts as a scavenger of ROS, thereby potentially protecting cells from harmful oxidative products. While most eukaryotes synthesize ascorbic acid, yeast cells produce erythro-ascorbic acid instead. The actual importance of this antioxidant substance for the yeast is still a subject of scientific debate. METHODOLOGY/PRINCIPAL FINDINGS: We set out to enable Saccharomyces cerevisiae cells to produce ascorbic acid intracellularly to protect the cells from detrimental effects of environmental stresses. We report for the first time the biosynthesis of L-ascorbic acid from D-glucose by metabolically engineered yeast cells. The amount of L-ascorbic acid produced leads to an improved robustness of the recombinant cells when they are subjected to stress conditions as often met during industrial fermentations. Not only resistance against oxidative agents as H(2O(2 is increased, but also the tolerance to low pH and weak organic acids at low pH is increased. CONCLUSIONS/SIGNIFICANCE: This platform provides a new tool whose commercial applications may have a substantial impact on bio-industrial production of Vitamin C. Furthermore, we propose S. cerevisiae cells endogenously producing vitamin C as a cellular model to study the genesis/protection of ROS as well as genotoxicity.

The impact of acute stress on the neural processing of food cues in bulimia nervosa: Replication in two samples.

Science.gov (United States)

Collins, Brittany; Breithaupt, Lauren; McDowell, Jennifer E; Miller, L Stephen; Thompson, James; Fischer, Sarah

2017-07-01

The impact of acute stress on the neural processing of food cues in bulimia nervosa (BN) is unknown, despite theory that acute stress decreases cognitive control over food and hence increases vulnerability to environmental triggers for binge eating. Thus, the goals of this manuscript were to explore the impact of acute stress on the neural processing of food cues in BN. In Study 1, 10 women with Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5; American Psychiatric Association, 2013) BN and 10 healthy controls participated in an fMRI paradigm examining the neural correlates of visual food cue processing pre and post an acute stress induction. Whole brain analysis indicated that women with BN exhibited significant decreases in activation in the precuneus, associated with self-referential processing, the paracingulate gyrus, and the anterior vermis of the cerebellum. Healthy controls exhibited increased activation in these regions in response to food cues poststress. In Study 2, 17 women with DSM-5 BN or otherwise specified feeding and eating disorder with BN symptoms participated in the same paradigm. A region of interest analysis replicated findings from Study 1. Replication of imaging findings in 2 different samples suggests the potential importance of these regions in relation to BN. Decreased activation in the precuneus, specifically, is consistent with models of BN that posit that binge eating serves as a concrete distraction from aversive internal stimuli. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Employee Communication during Crises: The Effects of Stress on Information Processing.

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Pincus, J. David; Acharya, Lalit

Based on multidisciplinary research findings, this report proposes an information processing model of employees' response to highly stressful information environments arising during organizational crises. The introduction stresses the importance of management's handling crisis communication with employees skillfully. The second section points out…

Overexpression of Grain Amaranth (Amaranthus hypochondriacus) AhERF or AhDOF Transcription Factors in Arabidopsis thaliana Increases Water Deficit- and Salt-Stress Tolerance, Respectively, via Contrasting Stress-Amelioration Mechanisms

Science.gov (United States)

Massange-Sánchez, Julio A.; Palmeros-Suárez, Paola A.; Espitia-Rangel, Eduardo; Rodríguez-Arévalo, Isaac; Sánchez-Segura, Lino; Martínez-Gallardo, Norma A.; Alatorre-Cobos, Fulgencio; Tiessen, Axel; Délano-Frier, John P.

2016-01-01

Two grain amaranth transcription factor (TF) genes were overexpressed in Arabidopsis plants. The first, coding for a group VII ethylene response factor TF (i.e., AhERF-VII) conferred tolerance to water-deficit stress (WS) in transgenic Arabidopsis without affecting vegetative or reproductive growth. A significantly lower water-loss rate in detached leaves coupled to a reduced stomatal opening in leaves of plants subjected to WS was associated with this trait. WS tolerance was also associated with an increased antioxidant enzyme activity and the accumulation of putative stress-related secondary metabolites. However, microarray and GO data did not indicate an obvious correlation between WS tolerance, stomatal closure, and abscisic acid (ABA)-related signaling. This scenario suggested that stomatal closure during WS in these plants involved ABA-independent mechanisms, possibly involving reactive oxygen species (ROS). WS tolerance may have also involved other protective processes, such as those employed for methyl glyoxal detoxification. The second, coding for a class A and cluster I DNA binding with one finger TF (i.e., AhDof-AI) provided salt-stress (SS) tolerance with no evident fitness penalties. The lack of an obvious development-related phenotype contrasted with microarray and GO data showing an enrichment of categories and genes related to developmental processes, particularly flowering. SS tolerance also correlated with increased superoxide dismutase activity but not with augmented stomatal closure. Additionally, microarray and GO data indicated that, contrary to AhERF-VII, SS tolerance conferred by AhDof-AI in Arabidopsis involved ABA-dependent and ABA-independent stress amelioration mechanisms. PMID:27749893

Overexpression of Grain Amaranth (Amaranthus hypochondriacus AhERF or AhDOF Transcription Factors in Arabidopsis thaliana Increases Water Deficit- and Salt-Stress Tolerance, Respectively, via Contrasting Stress-Amelioration Mechanisms.

Directory of Open Access Journals (Sweden)

Julio A Massange-Sánchez

Full Text Available Two grain amaranth transcription factor (TF genes were overexpressed in Arabidopsis plants. The first, coding for a group VII ethylene response factor TF (i.e., AhERF-VII conferred tolerance to water-deficit stress (WS in transgenic Arabidopsis without affecting vegetative or reproductive growth. A significantly lower water-loss rate in detached leaves coupled to a reduced stomatal opening in leaves of plants subjected to WS was associated with this trait. WS tolerance was also associated with an increased antioxidant enzyme activity and the accumulation of putative stress-related secondary metabolites. However, microarray and GO data did not indicate an obvious correlation between WS tolerance, stomatal closure, and abscisic acid (ABA-related signaling. This scenario suggested that stomatal closure during WS in these plants involved ABA-independent mechanisms, possibly involving reactive oxygen species (ROS. WS tolerance may have also involved other protective processes, such as those employed for methyl glyoxal detoxification. The second, coding for a class A and cluster I DNA binding with one finger TF (i.e., AhDof-AI provided salt-stress (SS tolerance with no evident fitness penalties. The lack of an obvious development-related phenotype contrasted with microarray and GO data showing an enrichment of categories and genes related to developmental processes, particularly flowering. SS tolerance also correlated with increased superoxide dismutase activity but not with augmented stomatal closure. Additionally, microarray and GO data indicated that, contrary to AhERF-VII, SS tolerance conferred by AhDof-AI in Arabidopsis involved ABA-dependent and ABA-independent stress amelioration mechanisms.

Posttraumatic Stress and Cognitive Processes in Patients with Burns

OpenAIRE

Sveen, Josefin

2011-01-01

A severe burn is one of the most traumatic injuries a person can experience. Posttraumatic stress disorder (PTSD) is relatively common after burns, and can be devastating for the individual’s possibilities for recovery. The principal aims were to gain knowledge regarding posttraumatic stress symptoms and cognitive processes after burn and to evaluate methods for assessing symptoms of PTSD up to one year after burn. The psychometric properties of a Swedish version of the Impact of Event Scale-...

Non destructive evaluation of residual stresses in welding and hard-surfacing processes

International Nuclear Information System (INIS)

Suarez, J.C.; Fernandez, L.M.; Cruz, C.; Aragon, B.; Merino, F.

1995-01-01

In this paper transversal and longitudinal stress profiles in welding and hard-surfacing by welding processes are presented. The stresses were measured by RMS of Barkhausen signal. In this work it is shown that in each case the level of stresses is strongly dependent on the number of weld beads of surfacing layers deposited. The subsequent deposition of new weld beads or surfacing layers produces a stress-relieving effect

0268 Is perceived stress related to an increase in salivary cortisol

DEFF Research Database (Denmark)

Fink, Samuel; Peter Bonde, Jens; Agergaard Vammen, Marianne

2014-01-01

OBJECTIVES: Perceived Stress is a suspected cause of many psychological and physical illnesses. However it remains to be discovered what physiological measures are involved. While it is widely known that acute stress leads to an increase in cortisol levels, the findings in prolonged stress research...... have not been consistent. This study explores the association between Perceived Stress and salivary cortisol levels using the largest population ever used in this field. METHOD: 4467 public employees in the PRISME cohort in 2007. 3217 of those did a similar follow up study in 2009. A 4-item Danish...... version of the PSS-scale was used to measure perceived stress and operationalized as the average score. Salivary cortisol samples were taken at 30 min post awakening and at 8 pm. A mean value of cortisol was calculated. In our analysis we applied logarithmic transformation to the concentrations. RESULTS...

The association between rotating shift work and increased occupational stress in nurses.

Science.gov (United States)

Lin, Pei-Chen; Chen, Chung-Hey; Pan, Shung-Mei; Chen, Yao-Mei; Pan, Chih-Hong; Hung, Hsin-Chia; Wu, Ming-Tsang

2015-01-01

The aim of this study was to investigate whether rotating shift work increases occupational stress in nurses. This study measured shift work scheduling and occupational stress by using the Effort-Reward Imbalance model with self-reported questionnaires in a sample of 654 female nurses. Overcommitment risk was higher in nurses who worked rotating shifts than in those who worked day/non-night shifts (OR, 2.16; 95% CI, 1.03-4.66). However, an effort/reward imbalance was not directly associated with work schedules (OR, 1.88; 95% CI, 0.87-4.35). Among nurses working rotation rotating shifts, those who had 2 days off after their most recent night shifts showed an alleviated risk of overcommitment (OR, 0.52; 95% CI, 0.32-0.82), but those who had worked for at least one series of 7 consecutive work days per month had an increased risk of effort/reward imbalance (OR, 2.75; 95% CI, 1.69-4.48). Additionally, those who had little or no participation in planning working hours and shift scheduling and worked overtime at least three times per week during the preceding 2 months tended to have high stress. The nurses who worked rotating shifts tended to experience work-related stress, but their stress levels improved if they had at least 2 days off after their most recent night shift and if they were not scheduled to work 7 consecutive days. These empirical data can be used to optimize work schedules for nurses to alleviate work stress.

Increased intracellular proteolysis reduces disease severity in an ER stress-associated dwarfism.

Science.gov (United States)

Mullan, Lorna A; Mularczyk, Ewa J; Kung, Louise H; Forouhan, Mitra; Wragg, Jordan Ma; Goodacre, Royston; Bateman, John F; Swanton, Eileithyia; Briggs, Michael D; Boot-Handford, Raymond P

2017-10-02

The short-limbed dwarfism metaphyseal chondrodysplasia type Schmid (MCDS) is linked to mutations in type X collagen, which increase ER stress by inducing misfolding of the mutant protein and subsequently disrupting hypertrophic chondrocyte differentiation. Here, we show that carbamazepine (CBZ), an autophagy-stimulating drug that is clinically approved for the treatment of seizures and bipolar disease, reduced the ER stress induced by 4 different MCDS-causing mutant forms of collagen X in human cell culture. Depending on the nature of the mutation, CBZ application stimulated proteolysis of misfolded collagen X by either autophagy or proteasomal degradation, thereby reducing intracellular accumulation of mutant collagen. In MCDS mice expressing the Col10a1.pN617K mutation, CBZ reduced the MCDS-associated expansion of the growth plate hypertrophic zone, attenuated enhanced expression of ER stress markers such as Bip and Atf4, increased bone growth, and reduced skeletal dysplasia. CBZ produced these beneficial effects by reducing the MCDS-associated abnormalities in hypertrophic chondrocyte differentiation. Stimulation of intracellular proteolysis using CBZ treatment may therefore be a clinically viable way of treating the ER stress-associated dwarfism MCDS.

Stress og aldring

DEFF Research Database (Denmark)

Jørgensen, Anders; Jørgensen, Martin Balslev; Poulsen, Henrik Enghusen

2012-01-01

Accumulating evidence supports the popular notion that psychological stress states may accelerate aging. Stress has been shown to influence cellular systems known to be involved in the aging process. Furthermore, stress is associated with an increased risk of various age-related medical disorders....... These effects are likely mediated by the secretion of stress hormones. In this short review we focus on biochemical and epidemiological evidence for a link between stress and aging....

Apelin-APJ system is responsible for stress-induced increase in atrial natriuretic peptide expression in rat heart.

Science.gov (United States)

Izgut-Uysal, Vecihe Nimet; Acar, Nuray; Birsen, Ilknur; Ozcan, Filiz; Ozbey, Ozlem; Soylu, Hakan; Avci, Sema; Tepekoy, Filiz; Akkoyunlu, Gokhan; Yucel, Gultekin; Ustunel, Ismail

2018-04-01

The cardiovascular system is a primary target of stress and stress is the most important etiologic factor in cardiovascular diseases. Stressors increase expressions of atrial natriuretic peptide (ANP) and apelin in cardiac tissue. The aim of the present study was to investigate whether stress-induced apelin has an effect on the expression of ANP in the right atrium of rat heart. The rats were divided into the control, stress and F13A+stress groups. In the stress and F13A+stress groups, the rats were subjected to water immersion and restraint stress (WIRS) for 6h. In the F13A+stress group, apelin receptor antagonist F13A, was injected intravenously immediately before application of WIRS. The plasma samples were obtained for the measurement of corticosterone and atrial natriuretic peptide. The atrial samples were used for immunohistochemistry and western blot analysis. F13A administration prevented the rise of plasma corticosterone and ANP levels induced by WIRS. While WIRS application increased the expressions of apelin, HIF-1α and ANP in atrial tissue, while F13A prevented the stress-induced increase in the expression of HIF-1α and ANP. Stress-induced apelin induces ANP expression in atrial tissue and may play a role in cardiovascular homeostasis by increasing ANP expression under WIRS conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Exposure of rat hippocampal astrocytes to Ziram increases oxidative stress.

Science.gov (United States)

Matei, Ann-Marie; Trombetta, Louis D

2016-04-01

Pesticides have been shown in several studies to be the leading candidates of environmental toxins and may contribute to the pathogenesis of several neurodegenerative diseases. Ziram (zinc-bis(dimethyldithiocarbamate)) is an agricultural dithiocarbamate fungicide that is used to treat a variety of plant diseases. In spite of their generally acknowledged low toxicity, dithiocarbamates are known to cause a wide range of neurobehavioral effects as well as neuropathological changes in the brain. Astrocytes play a key role in normal brain physiology and in the pathology of the nervous system. This investigation studied the effects of 1.0 µM Ziram on rat hippocampal astrocytes. The thiobarbituric acid reactive substance assay performed showed a significant increase in malondialdehyde, a product of lipid peroxidation, in the Ziram-treated cells. Biochemical analysis also revealed a significant increase in the induction of 70 kDa heat shock and heme oxygenase 1 stress proteins. In addition, an increase of glutathione peroxidase (GPx) and a significant increase in oxidized glutathione (GSSG) were observed in the Ziram-treated cells. The ratio GSH to GSSG calculated from the treated cells was also decreased. Light and transmission electron microscopy supported the biochemical findings in Ziram-treated astrocytes. This data suggest that the cytotoxic effects observed with Ziram treatments may be related to the increase of oxidative stress. © The Author(s) 2013.

Oxidative stress increases internal calcium stores and reduces a key mitochondrial enzyme.

Science.gov (United States)

Gibson, Gary E; Zhang, Hui; Xu, Hui; Park, Larry C H; Jeitner, Thomas M

2002-03-16

Fibroblasts from patients with genetic and non-genetic forms of Alzheimer's disease (AD) show many abnormalities including increased bombesin-releasable calcium stores (BRCS), diminished activities of the mitochondrial alpha-ketoglutarate dehydrogenase complex (KGDHC), and an altered ability to handle oxidative stress. The link between genetic mutations (and the unknown primary event in non-genetic forms) and these other cellular abnormalities is unknown. To determine whether oxidative stress could be a convergence point that produces the other AD-related changes, these experiments tested in fibroblasts the effects of H(2)O(2), in the presence or absence of select antioxidants, on BRCS and KGDHC. H(2)O(2) concentrations that elevated carboxy-dichlorofluorescein (c-H(2)DCF)-detectable ROS increased BRCS and decreased KGDHC activity. These changes are in the same direction as those in fibroblasts from AD patients. Acute treatments with the antioxidants Trolox, or DMSO decreased c-H(2)DCF-detectable ROS by about 90%, but exaggerated the H(2)O(2)-induced increases in BRCS by about 4-fold and did not alter the reduction in KGDHC. Chronic pretreatments with Trolox more than doubled the BRCS, tripled KGDHC activities, and reduced the effects of H(2)O(2). Pretreatment with DMSO or N-acetyl cysteine diminished the BRCS and either had no effect, or exaggerated the H(2)O(2)-induced changes in these variables. The results demonstrate that BRCS and KGDHC are more sensitive to H(2)O(2) derived species than c-H(2)DCF, and that oxidized derivatives of the antioxidants exaggerate the actions of H(2)O(2). The findings support the hypothesis that select abnormalities in oxidative processes are a critical part of a cascade that leads to the cellular abnormalities in cells from AD patients.

Stress and organisational citizenship behaviours in Indian business process outsourcing organisations

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Ajay K. Jain

2012-09-01

Full Text Available This study investigates the direct effect of organisational stress (as measured through ASSET on organisational citizenship behaviours (OCBs. A sample of 402 operators was taken from business process outsourcing (BPO organisations located in northern India. The authors hypothesised that there is a negative relationship between organisational stress and OCBs. Results of multiple regression analysis showed that stress had significant negative impact on OCBs. The implications for managers are discussed.

Cold stress improves the production of artemisinin depending on the increase in endogenous jasmonate.

Science.gov (United States)

Liu, Wanhong; Wang, Huanyan; Chen, Yupei; Zhu, Shunqin; Chen, Min; Lan, Xiaozhong; Chen, Guoping; Liao, Zhihua

2017-05-01

Previous publications reported that the artemisinin level was increased in Artemisia annua following a night-frost period. However, the molecular mechanism was not clear. In this study, we found that exogenous jasmonate (JA) effectively enhanced the freezing tolerance of A. annua. The JA biosynthetic genes (LOX1, LOX2, allene oxide cyclase [AOC], and jasmonate resistant 1 [JAR1]) were induced by cold stress, leading to an increase in endogenous JA in cold-treated A. annua. Increased endogenous JA enhanced the expression of three JA-responsive transcription factors, ethylene response factor 1, ethylene response factor 2, and octadecanoid-responsive AP2/ERF, all of which were reported to transcriptionally activate the expression of artemisinin biosynthetic genes, such as amorpha-4,11-diene synthase (ADS), CYP71AV1, DBR2, and aldehyde dehydrogenase 1 (ALDH1). Furthermore, the expression levels of the four artemisinin biosynthetic genes were also significantly increased under cold stress. Consequently, the levels of artemisinin and related secondary metabolites, such as dihydroartemisinic acid, artemisinin B, and artemisinic acid, were increased in A. annua under cold stress. Our study points to a molecular mechanism in which the production of artemisinin is regulated by cold stress in A. annua. © 2016 International Union of Biochemistry and Molecular Biology, Inc.

Stress during adolescence increases novelty seeking and risk taking behavior in male and female rats

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Maria eToledo

2011-04-01

Full Text Available Adolescence is a period of major physical, hormonal and psychological change. It is also characterized by a significant increase in the incidence of psychopathologies and this increase is gender-specific. Likewise, stress during adolescence is associated with the development of psychiatric disorders later in life. Previously, using a rat model of psychogenic stress (exposure to predator odor followed by placement on an elevated platform during the pre-pubertal period (postnatal days 28-30, we reported sex-specific effects on auditory and contextual fear conditioning. Here, we study the short-term impact of psychogenic stress before and during puberty (postnatal days 28-42 on behavior (novelty seeking, risk taking, anxiety and depression and hypothalamus-pituitary-adrenocortical (HPA axis activation during late adolescence (postnatal days 45-51. Peri-pubertal stress decreased anxiety-like behavior and increased risk taking and novelty seeking behaviors during late adolescence (measured with the elevated plus maze, open field and exposure to novel object tests and intake of chocopop pellets before or immediate after stress. Finally neither depressive-like behavior (measured at the forced swim test nor HPA response to stress (blood corticosterone and glucose were affected by peri-pubertal stress. Nevertheless, when controlling for the basal anxiety of the mothers, animals exposed to peri-pubertal stress showed a significant decrease in corticosterone levels immediate after an acute stressor. The results from this study suggest that exposure to mild stressors during the peri-pubertal period induces a broad spectrum of behavioral changes in late adolescence, which may exacerbate the independence-building behaviors naturally happening during this transitional period (increase in curiosity, sensation-seeking and risk taking behaviors.

Effect of Tip Shape of Frictional Stir Burnishing Tool on Processed Layer’s Hardness, Residual Stress and Surface Roughness

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Yoshimasa Takada

2018-01-01

Full Text Available Friction stir burnishing (FSB is a surface-enhancement method used after machining, without the need for an additional device. The FSB process is applied on a machine that uses rotation tools (e.g., machining center or multi-tasking machine. Therefore, the FSB process can be applied immediately after the cutting process using the same machine tool. Here, we apply the FSB to the shaft materials of 0.45% C steel using a multi-tasking machine. In the FSB process, the burnishing tool rotates at a high-revolution speed. The thin surface layer is rubbed and stirred as the temperature is increased and decreased. With the FSB process, high hardness or compressive residual stress can be obtained on the surface layer. However, when we applied the FSB process using a 3 mm diameter sphere tip shape tool, the surface roughness increased substantially (Ra = 20 µm. We therefore used four types of tip shape tools to examine the effect of burnishing tool tip radius on surface roughness, hardness, residual stress in the FSB process. Results indicated that the surface roughness was lowest (Ra = 10 µm when the tip radius tool diameter was large (30 mm.

Increasing fatty acid oxidation remodels the hypothalamic neurometabolome to mitigate stress and inflammation.

Directory of Open Access Journals (Sweden)

Joseph W McFadden

Full Text Available Modification of hypothalamic fatty acid (FA metabolism can improve energy homeostasis and prevent hyperphagia and excessive weight gain in diet-induced obesity (DIO from a diet high in saturated fatty acids. We have shown previously that C75, a stimulator of carnitine palmitoyl transferase-1 (CPT-1 and fatty acid oxidation (FAOx, exerts at least some of its hypophagic effects via neuronal mechanisms in the hypothalamus. In the present work, we characterized the effects of C75 and another anorexigenic compound, the glycerol-3-phosphate acyltransferase (GPAT inhibitor FSG67, on FA metabolism, metabolomics profiles, and metabolic stress responses in cultured hypothalamic neurons and hypothalamic neuronal cell lines during lipid excess with palmitate. Both compounds enhanced palmitate oxidation, increased ATP, and inactivated AMP-activated protein kinase (AMPK in hypothalamic neurons in vitro. Lipidomics and untargeted metabolomics revealed that enhanced catabolism of FA decreased palmitate availability and prevented the production of fatty acylglycerols, ceramides, and cholesterol esters, lipids that are associated with lipotoxicity-provoked metabolic stress. This improved metabolic signature was accompanied by increased levels of reactive oxygen species (ROS, and yet favorable changes in oxidative stress, overt ER stress, and inflammation. We propose that enhancing FAOx in hypothalamic neurons exposed to excess lipids promotes metabolic remodeling that reduces local inflammatory and cell stress responses. This shift would restore mitochondrial function such that increased FAOx can produce hypothalamic neuronal ATP and lead to decreased food intake and body weight to improve systemic metabolism.

Residual stress evaluation and curvature behavior of aluminium 7050 peen forming processed; Avaliacao da tensao residual em aluminio 7050 conformado pelo processo peen forming

Energy Technology Data Exchange (ETDEWEB)

Oliveira, R.R. de; Lima, N.B., E-mail: rolivier@ipen.b, E-mail: nblima@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Braga, A.P.V.; Goncalves, M., E-mail: anapaola@ipt.b, E-mail: mgoncalves@ipt.b [Instituto de Pesquisas Tecnologicas (IPT), Sao Paulo, SP (Brazil)

2010-07-01

Shot peening is a superficial cold work process used to increase the fatigue life evaluated by residual stress measurements. The peen forming process is a variant of the shot peening process, where a curvature in the plate is obtained by the compression of the grains near to the surface. In this paper, the influence of the parameters such as: pressure of shot, ball shot size and thickness of aluminum 7050 samples with respect to residual stress profile and resulting arc height was studied. The evaluation of the residual stress profile was obtained by sin{sup 2} {Psi} method. (author)

Protein oxidative stress markers in peritoneal fluids of women with deep infiltrating endometriosis are increased.

Science.gov (United States)

Santulli, Pietro; Chouzenoux, Sandrine; Fiorese, Mauro; Marcellin, Louis; Lemarechal, Herve; Millischer, Anne-Elodie; Batteux, Frédéric; Borderie, Didier; Chapron, Charles

2015-01-01

Are protein oxidative stress markers [thiols, advanced oxidation protein products (AOPP), protein carbonyls and nitrates/nitrites] in perioperative peritoneal fluid higher in women with histologically proven endometriosis when compared with endometriosis-free controls? Protein oxidative stress markers are significantly increased in peritoneal fluids from women with deep infiltrating endometriosis with intestinal involvement when compared with endometriosis-free controls. Endometriosis is a common gynaecologic condition characterized by an important inflammatory process. Various source of evidence support the role of oxidative stress in the development of endometriosis. We conducted a prospective laboratory study in a tertiary-care university hospital between January 2011 and December 2012, and included 235 non-pregnant women, younger than 42 year old, undergoing surgery for a benign gynaecological condition. After complete surgical exploration of the abdomino-pelvic cavity, 150 women with histologically proven endometriosis and 85 endometriosis-free controls women were enrolled. Women with endometriosis were staged according to a surgical classification in three different phenotypes of endometriosis: superficial peritoneal endometriosis (SUP), ovarian endometrioma (OMA) and deeply infiltrating endometriosis (DIE). Perioperative peritoneal fluids samples were obtained from all study participants. Thiols, AOPP, protein carbonyls and nitrates/nitrites were assayed in all peritoneal samples. Concentrations of peritoneal AOPP were significantly higher in endometriosis patients than in the control group (median, 128.9 µmol/l; range, 0.3-1180.1 versus median, 77.8 µmol/l; range, 0.8-616.1; P peritoneal nitrates/nitrites were higher in endometriosis patients than in the control group (median, 24.8 µmol/l; range, 1.6-681.6 versus median, 18.5 µmol/l; range, 1.6-184.5; P peritoneal fluids protein AOPP and nitrates/nitrites were significantly increased only in DIE samples

Effect of process variables on the Drucker-Prager cap model and residual stress distribution of tablets estimated by the finite element method.

Science.gov (United States)

Hayashi, Yoshihiro; Otoguro, Saori; Miura, Takahiro; Onuki, Yoshinori; Obata, Yasuko; Takayama, Kozo

2014-01-01

A multivariate statistical technique was applied to clarify the causal correlation between variables in the manufacturing process and the residual stress distribution of tablets. Theophylline tablets were prepared according to a Box-Behnken design using the wet granulation method. Water amounts (X1), kneading time (X2), lubricant-mixing time (X3), and compression force (X4) were selected as design variables. The Drucker-Prager cap (DPC) model was selected as the method for modeling the mechanical behavior of pharmaceutical powders. Simulation parameters, such as Young's modulus, Poisson rate, internal friction angle, plastic deformation parameters, and initial density of the powder, were measured. Multiple regression analysis demonstrated that the simulation parameters were significantly affected by process variables. The constructed DPC models were fed into the analysis using the finite element method (FEM), and the mechanical behavior of pharmaceutical powders during the tableting process was analyzed using the FEM. The results of this analysis revealed that the residual stress distribution of tablets increased with increasing X4. Moreover, an interaction between X2 and X3 also had an effect on shear and the x-axial residual stress of tablets. Bayesian network analysis revealed causal relationships between the process variables, simulation parameters, residual stress distribution, and pharmaceutical responses of tablets. These results demonstrated the potential of the FEM as a tool to help improve our understanding of the residual stress of tablets and to optimize process variables, which not only affect tablet characteristics, but also are risks of causing tableting problems.

Together in Pain: Attachment-Related Dyadic Processes and Posttraumatic Stress Disorder

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Ein-Dor, Tsachi; Doron, Guy; Solomon, Zahava; Mikulincer, Mario; Shaver, Phillip R.

2010-01-01

We used actor-partner interdependence modeling to explore associations among attachment-related dyadic processes, posttraumatic stress disorder (PTSD) in war veterans, and secondary traumatic stress (STS) in their wives. A sample of 157 Israeli couples (85 former prisoners of war and their wives and a comparison group of 72 veterans not held…

How does context affect intimate relationships? linking external stress and cognitive processes within marriage.

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Neff, Lisa A; Karney, Benjamin R

2004-02-01

Stressors external to the marriage frequently affect the way spouses evaluate their marital quality. To date, however, understanding of the interplay between external stress and internal relationship processes has been limited in two ways. First, research has generally examined only the short-term consequences of stress. Second, the mechanisms through which external stressors influence relationship outcomes are unclear. This study addressed both limitations by examining relationship cognitions that may mediate the effects of external stress throughout 4 years of marriage. Analyses confirmed that stressful experiences were associated with the trajectory of marital quality overtime. Furthermore, both the content and the organization of spouses' specific relationship cognitions mediated this effect. That is, stress negatively influenced the nature of spouses' marital perceptions as well as the way spouses interpreted and processed those perceptions. These findings draw attention to ways that the context of relationships shapes and constrains relationship processes.

Increasing adult hippocampal neurogenesis in mice after exposure to unpredictable chronic mild stress may counteract some of the effects of stress.

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Culig, Luka; Surget, Alexandre; Bourdey, Marlene; Khemissi, Wahid; Le Guisquet, Anne-Marie; Vogel, Elise; Sahay, Amar; Hen, René; Belzung, Catherine

2017-11-01

Major depression is hypothesized to be associated with dysregulations of the hypothalamic-pituitary-adrenal (HPA) axis and impairments in adult hippocampal neurogenesis. Adult-born hippocampal neurons are required for several effects of antidepressants and increasing the rate of adult hippocampal neurogenesis (AHN) before exposure to chronic corticosterone is sufficient to protect against its harmful effects on behavior. However, it is an open question if increasing AHN after the onset of chronic stress exposure would be able to rescue behavioral deficits and which mechanisms might be involved in recovery. We investigated this question by using a 10-week unpredictable chronic mild stress (UCMS) model on a transgenic mouse line (iBax mice), in which the pro-apoptotic gene Bax can be inducibly ablated in neural stem cells following Tamoxifen injection, therefore enhancing the survival of newborn neurons in the adult brain. We did not observe any effect of our treatment in non-stress conditions, but we did find that increasing AHN after 2 weeks of UCMS is sufficient to counteract the effects of UCMS on certain behaviors (splash test and changes in coat state) and endocrine levels and thus to display some antidepressant-like effects. We observed that increasing AHN lowered the elevated basal corticosterone levels in mice exposed to UCMS. This was accompanied by a tamoxifen-induced reversal of the lack of stress-induced decrease in neuronal activation in the anteromedial division of the bed nucleus of the stria terminalis (BSTMA) after intrahippocampal dexamethasone infusion, pointing to a possible mechanism through which adult-born neurons might have exerted their effects. Our results contribute to the neurogenesis hypothesis of depression by suggesting that increasing AHN may be beneficial not just before, but also after exposure to stress by counteracting several of its effects, in part through regulating the HPA axis. Copyright © 2017 Elsevier Ltd. All rights

Delayed memory effects after intense stress in Special Forces candidates: exploring path processes between cortisol secretion and memory recall.

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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.

Inflammatory stress increases hepatic CD36 translational efficiency via activation of the mTOR signalling pathway.

Directory of Open Access Journals (Sweden)

Chuan Wang

Full Text Available Inflammatory stress is an independent risk factor for the development of non-alcoholic fatty liver disease (NAFLD. Although CD36 is known to facilitate long-chain fatty acid uptake and contributes to NAFLD progression, the mechanisms that link inflammatory stress to hepatic CD36 expression and steatosis remain unclear. As the mammalian target of rapamycin (mTOR signalling pathway is involved in CD36 translational activation, this study was undertaken to investigate whether inflammatory stress enhances hepatic CD36 expression via mTOR signalling pathway and the underlying mechanisms. To induce inflammatory stress, we used tumour necrosis factor alpha (TNF-α and interleukin-6 (IL-6 stimulation of the human hepatoblastoma HepG2 cells in vitro and casein injection in C57BL/6J mice in vivo. The data showed that inflammatory stress increased hepatic CD36 protein levels but had no effect on mRNA expression. A protein degradation assay revealed that CD36 protein stability was not different between HepG2 cells treated with or without TNF-α or IL-6. A polysomal analysis indicated that CD36 translational efficiency was significantly increased by inflammatory stress. Additionally, inflammatory stress enhanced the phosphorylation of mTOR and its downstream translational regulators including p70S6K, 4E-BP1 and eIF4E. Rapamycin, an mTOR-specific inhibitor, reduced the phosphorylation of mTOR signalling pathway and decreased the CD36 translational efficiency and protein level even under inflammatory stress resulting in the alleviation of inflammatory stress-induced hepatic lipid accumulation. This study demonstrates that the activation of the mTOR signalling pathway increases hepatic CD36 translational efficiency, resulting in increased CD36 protein expression under inflammatory stress.

Early Childhood Stress and Child Age Predict Longitudinal Increases in Obesogenic Eating Among Low-Income Children.

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Miller, Alison L; Gearhardt, Ashley N; Retzloff, Lauren; Sturza, Julie; Kaciroti, Niko; Lumeng, Julie C

2018-01-31

To identify whether psychosocial stress exposure during early childhood predicts subsequent increased eating in the absence of hunger (EAH), emotional overeating, food responsiveness, and enjoyment of food. This was an observational longitudinal study. Among 207 low-income children (54.6% non-Hispanic white, 46.9% girls), early childhood stress exposure was measured by parent report and a stress exposure index calculated, with higher scores indicating more stress exposure. Eating behaviors were measured in early (mean, 4.3; standard deviation, 0.5 years) and middle (mean, 7.9; standard deviation, 0.7 years) childhood. Observed EAH was assessed by measuring kilocalories of palatable food the child consumed after a meal. Parents reported on child eating behaviors on the Child Eating Behavior Questionnaire. Child weight and height were measured and body mass index z score (BMIz) calculated. Multivariable linear regression, adjusting for child sex, race/ethnicity, and BMIz, was used to examine the association of stress exposure with rate of change per year in each child eating behavior. Early childhood stress exposure predicted yearly increases in EAH (β = 0.14; 95% confidence interval, 0.002, 0.27) and Emotional Overeating (β = 0.14; 95% confidence interval, 0.008, 0.27). Stress exposure was not associated with Food Responsiveness (trend for decreased Enjoyment of Food; β = -0.13; 95% confidence interval, 0.002, -0.26). All child obesogenic eating behaviors increased with age (P Early stress exposure predicted increases in child eating behaviors known to associate with overweight/obesity. Psychosocial stress may confer overweight/obesity risk through eating behavior pathways. Targeting eating behaviors may be an important prevention strategy for children exposed to stress. Copyright © 2018 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

Numerical analysis of stress fields generated by quenching process

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A. Bokota

2011-04-01

Full Text Available In work the presented numerical models of tool steel hardening processes take into account mechanical phenomena generated by thermalphenomena and phase transformations. In the model of mechanical phenomena, apart from thermal, plastic and structural strain, alsotransformations plasticity was taken into account. The stress and strain fields are obtained using the solution of the Finite Elements Method of the equilibrium equation in rate form. The thermophysical constants occurring in constitutive relation depend on temperature and phase composite. For determination of plastic strain the Huber-Misses condition with isotropic strengthening was applied whereas fordetermination of transformation plasticity a modified Leblond model was used. In order to evaluate the quality and usefulness of thepresented models a numerical analysis of stresses and strains associated hardening process of a fang lathe of cone shaped made of tool steel was carried out.

Increased sensitivity to salt stress in tocopherol-deficient Arabidopsis mutants growing in a hydroponic system

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Ellouzi, Hasna; Hamed, Karim Ben; Cela, Jana; Müller, Maren; Abdelly, Chedly; Munné-Bosch, Sergi

2013-01-01

Recent studies suggest that tocopherols could play physiological roles in salt tolerance but the mechanisms are still unknown. In this study, we analyzed changes in growth, mineral and oxidative status in vte1 and vte4 Arabidopsis thaliana mutants exposed to salt stress. vte1 and vte4 mutants lack α-tocopherol, but only the vte1 mutant is additionally deficient in γ-tocopherol. Results showed that a deficiency in vitamin E leads to reduced growth and increased oxidative stress in hydroponically-grown plants. This effect was observed at early stages, not only in rosettes but also in roots. The vte1 mutant was more sensitive to salt-induced oxidative stress than the wild type and the vte4 mutant. Salt sensitivity was associated with (i) high contents of Na+, (ii) reduced efficiency of PSII photochemistry (Fv/Fm ratio) and (iii) more pronounced oxidative stress as indicated by increased hydrogen peroxide and malondialdeyde levels. The vte 4 mutant, which accumulates γ- instead of α-tocopherol showed an intermediate sensitivity to salt stress between the wild type and the vte1 mutant. Contents of abscisic acid, jasmonic acid and the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid were higher in the vte1 mutant than the vte4 mutant and wild type. It is concluded that vitamin E-deficient plants show an increased sensitivity to salt stress both in rosettes and roots, therefore indicating the positive role of tocopherols in stress tolerance, not only by minimizing oxidative stress, but also controlling Na+/K+ homeostasis and hormonal balance. PMID:23299430

Effect of Trinexapac-ethyl on Increased Resistance to Drought Stress in Wheatgrass (Agropyron desertorum L.

Directory of Open Access Journals (Sweden)

mohamad hossein sheikh mohamadi

2017-10-01

Full Text Available Introduction: Drought is one of the most detrimental abiotic stresses for turfgrass growth across a wide range of geographic locations. Most cool-season grass species are not well adapted to extended periods of drought, particularly during summer months. Decline in turf quality caused by drought stress is a major concern in turfgrass culture. Therefore, developing management practices for improving drought resistance of turfgrasses has become essential in arid and semi-arid regions, especially during water use restriction. One strategy to improve plant drought resistance is to promote drought avoidance by reducing water loss during drought, which may be achieved by slowing growth rate of shoots and lowering leaf area canopy to reduce demand for water. Application of growth regulators is one of the methods for increasing resistance of plants to biotic and abiotic stresses. Trinexapac-ethyl (TE is one of the most widely used PGRs in the management of cool-season and warm-season turfgrass species. TE absorbed quickly by foliage and slow cell elongation through inhibiting of converting one form of gibberellic acid (GA20 to another (GA1. Most studies conducted under non-stressed conditions found that TE application increased chlorophyll content, turf quality, turf density and reduced shoot extension rate. We hypothesized that TE may influence plant tolerance to drought stress. Limited available data─ as reported in the above referred studies─ suggest that TE application may be beneficial for plant tolerance to stresses, but the effectiveness varies with turfgrass species, dose and duration of TE treatment, and type of stress. The main aim of this research is to evaluate the effect of Trinexapac-ethyl on increased resistance to drought stress in wheatgrass. Materials and Methods: Wheatgrass (Agropyron desertorum L. was used in this study. This study was conducted in field conditions at Isfahan University of Technology, Isfahan, Iran.. Wheatgrass

Marital Processes, Neuroticism, and Stress as Risk Factors for Internalizing Symptoms.

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Brock, Rebecca L; Lawrence, Erika

2014-03-01

Marital discord has a robust association with depression, yet it is rarely considered within broader etiological frameworks of psychopathology. Further, little is known about the particular aspects of relationships that have the greatest impact on psychopathology. The purpose of the present study was to test a novel conceptual framework including neuroticism, specific relationship processes (conflict management, partner support, emotional intimacy, and distribution of power and control), and stress as predictors of internalizing symptoms (depression and anxiety). Questionnaire and interview data were collected from 103 husbands and wives 5 times over the first 7 years of marriage. Results suggest that neuroticism (an expression of the underlying vulnerability for internalizing disorders) contributes to symptoms primarily through high levels of non-marital stress, an imbalance of power/control in one's marriage, and poor partner support for husbands, and through greater emotional disengagement for wives. Marital processes, neuroticism, and stress work together to significantly predict internalizing symptoms, demonstrating the need to routinely consider dyadic processes in etiological models of individual psychopathology. Specific recommendations for adapting and implementing couple interventions to prevent and treat individual psychopathology are discussed.

Effect of power history on the shape and the thermal stress of a large sapphire crystal during the Kyropoulos process

Science.gov (United States)

Nguyen, Tran Phu; Chuang, Hsiao-Tsun; Chen, Jyh-Chen; Hu, Chieh

2018-02-01

In this study, the effect of the power history on the shape of a sapphire crystal and the thermal stress during the Kyropoulos process are numerically investigated. The simulation results show that the thermal stress is strongly dependent on the power history. The thermal stress distributions in the crystal for all growth stages produced with different power histories are also studied. The results show that high von Mises stress regions are found close to the seed of the crystal, the highly curved crystal surface and the crystal-melt interface. The maximum thermal stress, which occurs at the crystal-melt interface, increases significantly in value as the crystal expands at the crown. After this, there is reduction in the maximum thermal stress as the crystal lengthens. There is a remarkable enhancement in the maximum von Mises stress when the crystal-melt interface is close to the bottom of the crucible. There are two obvious peaks in the maximum Von Mises stress, at the end of the crown stage and in the final stage, when cracking defects can form. To alleviate this problem, different power histories are considered in order to optimize the process to produce the lowest thermal stress in the crystal. The optimal power history is found to produce a significant reduction in the thermal stress in the crown stage.

Ozone Exposure Increases Circulating Stress Hormones and Lipid Metabolites in Humans

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RATIONALE: Air pollution has been associated with increased prevalence of type 2 diabetes; however, the mechanisms remain unknown. We have shown that acute ozone exposure in rats induces release of stress hormones, hyperglycemia, leptinemia, and gluoose intolerance that are assoc...

Progesterone pretreatment increases the stress response to social isolation in ewes.

Science.gov (United States)

Freitas-de-Melo, Aline; Damián, Juan Pablo; Hötzel, Maria José; Banchero, Georgget; Ungerfeld, Rodolfo

2016-01-01

In rodents, progesterone (P4) pretreatment increases anxiety and response to stressors. Social isolation is a stressor that generates physiological and behavioural stress responses in sheep. The aim of the study was to compare the stress response of anoestrous ewes previously treated or not with P4 to the social isolation test. Ten ewes received P4 treatment during 13 d (group P4-W) and another 10 remained untreated as controls (group Con). The ewes were individually isolated in a novel place during 10 min, 24 h after the end of P4 pretreatment and their behaviours were recorded. Cortisol and P4 concentrations as well as body surface temperature were recorded before and after the test. Ewes of the P4-W group presented higher cortisol levels 0, 10, 20 and 30 min after the social isolation and had greater area under the curve of cortisol compared to Con ewes (41,785%±4,156% vs. 25,682%±4,565% during 75 min). Progesterone and body surface temperature increased after social isolation, with no differences between P4-W and Con ewes. There were no differences in behavioural responses to social isolation. P4 pretreatment appears to augment the stress response to social isolation in anoestrous ewes.

Acute Stress Decreases but Chronic Stress Increases Myocardial Sensitivity to Ischemic Injury in Rodents

OpenAIRE

Eisenmann, Eric D.; Rorabaugh, Boyd R.; Zoladz, Phillip R.

2016-01-01

Cardiovascular disease is the largest cause of mortality worldwide, and stress is a significant contributor to the development of cardiovascular disease. The relationship between acute and chronic stress and cardiovascular disease is well-evidenced. Acute stress can lead to arrhythmias and ischemic injury. However, recent evidence in rodent models suggests that acute stress can decrease sensitivity to myocardial ischemia-reperfusion injury. Conversely, chronic stress is arrythmogenic and incr...

Heat-stress increase under climate change twice as large in cities as in rural areas

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Wouters, Hendrik; De Ridder, Koen; Poelmans, Lien; Willems, Patrick; Brouwers, Johan; Hosseinzadehtalaei, Parisa; Tabari, Hossein; Vanden Broucke, Sam; van Lipzig, Nicole P. M.; Demuzere, Matthias

2017-04-01

Urban areas, being warmer than their surroundings, are particularly vulnerable to global warming and associated increases in extreme temperatures. Yet ensemble climate-model projections are generally performed on a scale that is too coarse to represent the evolution of temperatures in cities. Here, for the first time, we combine a 35-year convection-permitting climate model integrations with information from an ensemble of general circulation models to assess heat stress in a typical densely populated mid-latitude maritime region. We show that the heat-stress increase for the mid-21st century is twice as large in cities compared to their surrounding rural areas. The exacerbation is driven by the urban heat island itself, its concurrence with heatwaves, and urban expansion. Cities experience a heat-stress multiplication by a factor 1.4 and 15 depending on the scenario. Remarkably, the future heat-stress surpasses everywhere the urban hot spots of today. Our novel insights exemplify the need to combine information from climate models, acting on different scales, for climate-change risk assessment in heterogeneous regions. Moreover, these results highlight the necessity for adaptation to increasing heat stress, especially in urban areas.

Stress Induced Charge-Ordering Process in LiMn_2O_4

International Nuclear Information System (INIS)

Chen, Yan; Yu, Dunji; An, Ke

2016-01-01

In this letter we report the stress-induced Mn charge-ordering process in the LiMn_2O_4 spinel, evidenced by the lattice strain evolutions due to the Jahn–Teller effects. In situ neutron diffraction reveals the initial stage of this process at low stress, indicating the eg electron localization at the preferential Mn sites during the early phase transition as an underlying charge-ordering mechanism in the charge-frustrated LiMn_2O_4. The initial stage of this transition exhibits as a progressive lattice and charge evolution, without showing a first-order behavior.

Stress og insomni

DEFF Research Database (Denmark)

Jennum, Poul; Zachariae, Bobby

2012-01-01

Insomnia and stress are two conditions, which are strongly associated and appear to be pathophysiologically integrated: the occurrence of stress increases the risk of insomnia, insomnia exacerbates stress, and coexistence of both factors has a negative influence on their prognosis. Stress...... and insomnia thus share complex interactions and the mechanisms involved are insufficiently understood but involve both psychological and physiological processes. First choice interventions involve behavioural and cognitive strategies and, to a lesser extent, pharmacological treatment....

Chewing suppresses the stress-induced increase in the number of pERK-immunoreactive cells in the periaqueductal grey.

Science.gov (United States)

Yamada, Kentaro; Narimatsu, Yuri; Ono, Yumie; Sasaguri, Ken-Ichi; Onozuka, Minoru; Kawata, Toshitsugu; Yamamoto, Toshiharu

2015-07-10

We investigated the effects of chewing under immobilization stress on the periaqueductal gray (PAG) matter using phosphorylated extracellular signal-regulated kinase (pERK) as a marker of responding cells. Immobilization stress increased pERK-immunoreactive cells in the PAG. Among four subdivisions of the PAG, the increase of immunoreactive cells was remarkable in the dorsolateral and ventrolateral subdivisions. However, increase of pERK-immunoreactive cells by the immobilization stress was not so evident in the dorsomedial and lateral subdivisions. The chewing under immobilization stress prevented the stress-induced increase of pERK-immunoreactive cells in the dorsolateral and ventrolateral subdivisions with statistical significances (p<0.05). Again, chewing effects on pERK-immunoreactive cells were not visible in the dorsomedial and lateral subdivisions. These results suggest that the chewing alleviates the PAG (dorsolateral and ventrolateral subdivisions) responses to stress. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Academic examination stress increases disordered eating symptomatology in female university students.

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Costarelli, V; Patsai, A

2012-09-01

It is well documented that stress and anxiety can affect eating behaviour and food intake in humans. The purpose of the current study was to explore the possible effect of academic examination stress on disordered eating attitudes, emotional eating, restraint eating, body image, anxiety levels and self-esteem in a group of female university students. The interrelationships of the above parameters were also examined. Sixty Greek female university students, 18-25 years old, have been recruited and completed, on two separate occasions: a) during an examination stress period, and b) during a control period, the following questionnaires: the Eating Attitudes Test (EAT-26), the Dutch Eating Behavior Questionnaire (DEBQ), the State-Trait Anxiety Inventory (STAI), the Rosenberg Self- Esteem Scale, the Body Image Pictorial Instrument Scale (COLLINS) and a specially designed General Background Questionnaire. Subjects reported significantly higher levels of disordered eating attitudes (EAT-26, p=0.01), higher levels of anxiety (p=0.000) and lower levels of self-esteem (p=0.016) during the examination stress period compared to the control period. Disordered eating attitudes (EAT-26) were significantly positively correlated with emotional eating (p=0.04) and restrained eating (p=0.010) and negatively correlated with levels of self-esteem (p=0.05) and perceived desired body image (p=0.008) during the exam stress period. Finally, EAT-26 was significantly positively correlated with levels of anxiety in both study periods. Academic examination stress seems to increase disordered eating symptomatology in female university students and is associated with lower levels of self-esteem, an important finding which warrants further investigation.

Chronic stress enhanced fear memories are associated with increased amygdala zif268 mRNA expression and are resistant to reconsolidation.

Science.gov (United States)

Hoffman, Ann N; Parga, Alejandro; Paode, Pooja R; Watterson, Lucas R; Nikulina, Ella M; Hammer, Ronald P; Conrad, Cheryl D

2015-04-01

The chronically stressed brain may present a vulnerability to develop maladaptive fear-related behaviors in response to a traumatic event. In rodents, chronic stress leads to amygdala hyperresponsivity and dendritic hypertrophy and produces a post traumatic stress disorder (PTSD)-like phenotype that includes exaggerated fear learning following Pavlovian fear conditioning and resistance to extinction. It is unknown whether chronic stress-induced enhanced fear memories are vulnerable to disruption via reconsolidation blockade, as a novel therapeutic approach for attenuating exaggerated fear memories. We used a chronic stress procedure in a rat model (wire mesh restraint for 6h/d/21d) to create a vulnerable brain that leads to a PTSD-like phenotype. We then examined freezing behavior during acquisition, reactivation and after post-reactivation rapamycin administration (i.p., 40mg/kg) in a Pavlovian fear conditioning paradigm to determine its effects on reconsolidation as well as the subsequent functional activation of limbic structures using zif268 mRNA. Chronic stress increased amygdala zif268 mRNA during fear memory retrieval at reactivation. Moreover, these enhanced fear memories were unaffected by post reactivation rapamycin to disrupt long-term fear memory. Also, post-reactivation long term memory processing was also associated with increased amygdala (LA and BA), and decreased hippocampal CA1 zif268 mRNA expression. These results suggest potential challenges for reconsolidation blockade as an effective approach in treating exaggerated fear memories, as in PTSD. Our findings also support chronic stress manipulations combined with fear conditioning as a useful preclinical approach to study a PTSD-like phenotype. Copyright © 2015 Elsevier Inc. All rights reserved.

Understanding psychological stress, its biological processes, and impact on primary headache.

Science.gov (United States)

Nash, Justin M; Thebarge, Ronald W

2006-10-01

Psychological stress is generally acknowledged to be a central contributor to primary headache. Stress results from any challenge or threat, either real or perceived, to normal functioning. The stress response is the body's activation of physiological systems, namely the hypothalamic-pituitary-adrenal axis, to protect and restore functioning. Chronic activation of the stress response can lead to wear and tear that eventually can predispose an individual to disease. There are multiple ways that stress and headache are closely related. Stress can (a) be a predisposing factor that contributes to headache disorder onset, (b) accelerate the progression of the headache disorder into a chronic condition, and (c) precipitate and exacerbate individual headache episodes. How stress impacts headache is not often understood. However, stress is assumed to affect primary headache by directly impacting pain production and modulation processes at both the peripheral and central levels. Stress can also independently worsen headache-related disability and quality of life. Finally, the headache experience itself can serve as a stressor that compromises an individual's health and well-being. With the prominent role that stress plays in headache, there are implications for the evaluation of stress and the use of stress reduction strategies at the various stages of headache disorder onset and progression. Future directions can help to develop a better empirical understanding of the pattern of the stress and headache connections and the mechanisms that explain the connections. Further research can also examine the interactive effects of stress and other factors that impact headache disorder onset, course, and adjustment.

Perceived Workplace Stress Is Associated with an Increased Risk of Prostate Cancer before Age 65.

Science.gov (United States)

Blanc-Lapierre, Audrey; Rousseau, Marie-Claude; Parent, Marie-Elise

2017-01-01

Evidence is lacking regarding the potential role of chronic psychological stress on cancer incidence. The workplace is reported to be the main source of stress among Canadian men. We examined the association between perceived lifetime workplace stress and prostate cancer (PCa) risk in a large case-control study. Cases were 1,933 men, aged ≤ 75 years, newly diagnosed with PCa in 2005-2009 across hospitals in Montreal, Canada. Concurrently, 1994 population controls frequency-matched on age were randomly selected from the electoral list based on cases' residential districts. Detailed lifestyle and work histories (including perceived stress, from any type of work stressor, for each job held) were collected during in-person interviews. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for the association between work-related stress and PCa risk in multivariate analyses. Over the lifetime, 58% of subjects reported at least one job as stressful. Occupations described as stressful were most often among white-collar workers. Perceived workplace stress duration was associated with a higher risk of PCa (OR = 1.12, 95% CI:1.04-1.20 per 10-year increase) among men younger than 65 years, but not among older men. Associations were similar irrespective of PCa aggressiveness. Frequent or recent screening for PCa, age at first exposure and time since exposure to work-related stress, and socioeconomic and lifestyle factors, had little influence on risk estimates. Findings are in line with an association between reporting prolonged workplace stress and an increase in risk of PCa before age 65.

Working the night shift causes increased vascular stress and delayed recovery in young women.

Science.gov (United States)

Lo, Shih-Hsiang; Lin, Lian-Yu; Hwang, Jing-Shiang; Chang, Yu-Yin; Liau, Chiau-Suong; Wang, Jung-Der

2010-08-01

Shiftwork has been associated with elevated blood pressure (BP) and decreased heart-rate variability (HRV), factors that may increase the long-term risk of cardiovascular-related mortality and morbidity. This study explored the effect of shiftwork on dynamic changes in autonomic control of HRV (cardiac stress), systolic BP and diastolic BP, i.e., SBP and DBP (vascular stress), and recovery in the same subjects working different shifts. By studying the same subjects, the authors could reduce the effect of possible contribution of between-subject variation from genetic predisposition and environmental factors. The authors recruited 16 young female nurses working rotating shifts--day (08:00-16:00 h), evening (16:00-00:00 h), and night (00:00-08:00 h)--and 6 others working the regular day shift. Each nurse received simultaneous and repeated 48-h ambulatory electrocardiography and BP monitoring during their work day and the following off-duty day. Using a linear mixed-effect model to adjust for day shift, the results of the repeated-measurements and self-comparisons found significant shift differences in vascular stress. While working the night shift, the nurses showed significant increases in vascular stress, with increased SBP of 9.7 mm Hg. The changes of SBP and DBP seemed to peak during waking time at the same time on the day off as they did on the working day. Whereas HRV profiles usually returned to baseline level after each shift, the SBP and DBP of night-shift workers did not completely return to baseline levels the following off-duty day (p night shift, they do not completely recover from increases in vascular stress on that day.

Methods for Alleviating Stress and Increasing Resilience in the Midwifery Community: A Scoping Review of the Literature.

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Wright, Erin M; Matthai, Maude Theo; Warren, Nicole

2017-11-01

Work-related stress and exposure to traumatic birth have deleterious impacts on midwifery practice, the midwife's physiologic well-being, and the midwifery workforce. This is a global phenomenon, and the specific sources of this stress vary dependent on practice setting. This scoping review aims to determine which, if any, modalities help to reduce stress and increase resilience among a population of midwives. A scoping review of the literature published between January 2011 and September 2016 using PubMed, CINAHL, Embase, PsycINFO, and Cochrane databases was performed. Of the initial 796 reviewed records, 6 met inclusion criteria. Three of the 6 included studies were quantitative in nature, 2 were qualitative, and one used mixed methods. Countries where studies were conducted include Uganda, Iran, the United Kingdom, Israel, and Australia. Three of the studies used interventions for stress reduction and increased coping. Two of these 3 used a mindfulness-based stress reduction program resulting in improved stress levels and coping skills. In each study, midwives express a desire for work-based programs and support from colleagues and employers for increasing coping abilities. These studies focused on stress reduction and/or increasing resilience. While modalities such as mindfulness-based stress reduction show promise, further studies with a cohort of midwives should be conducted. These studies should include interventions aimed at addressing the needs of midwives to improve psychological outcomes related to employment-related stress on a global scale and specific to each health care context. © 2017 by the American College of Nurse-Midwives.

Influences of Processing and Fatigue Cycling on Residual Stresses in a NiCrY-Coated Powder Metallurgy Disk Superalloy

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Gabb, T. P.; Rogers, R. B.; Nesbitt, J. A.; Miller, R. A.; Puleo, B. J.; Johnson, D.; Telesman, J.; Draper, S. L.; Locci, I. E.

2017-11-01

Oxidation and corrosion can attack superalloy disk surfaces exposed to increasing operating temperatures in some turbine engine environments. Any potential protective coatings must also be resistant to harmful fatigue cracking during service. The objective of this study was to investigate how residual stresses evolve in one such coating. Fatigue specimens of a powder metallurgy-processed disk superalloy were coated with a NiCrY coating, shot peened, and then subjected to fatigue in air at room and high temperatures. The effects of this processing and fatigue cycling on axial residual stresses and other aspects of the coating were assessed. While shot peening did induce beneficial compressive residual stresses in the coating and substrate, these stresses relaxed in the coating with subsequent heating. Several cast alloys having compositions near the coating were subjected to thermal expansion and tensile stress relaxation tests to help explain this response of residual stresses in the coating. For the coated fatigue specimens, this response contributed to earlier cracking of the coating than for the uncoated surface during long intervals of cycling at 760 °C. Yet, substantial compressive residual stresses still remained in the substrate adjacent to the coating, which were sufficient to suppress fatigue cracking there. The coating continued to protect the substrate from hot corrosion pitting, even after fatigue cracks initiated in the coating.

Neonatal maternal separation increases susceptibility to experimental colitis and acute stress exposure in male mice

Directory of Open Access Journals (Sweden)

Isabella M. Fuentes

2016-12-01

Full Text Available Experiencing early life stress can result in maladjusted stress response via dysregulation of the hypothalamic-pituitary-adrenal axis and serves as a risk factor for developing chronic pelvic pain disorders. We investigated whether neonatal maternal separation (NMS would increase susceptibility to experimental colitis or exposure to acute or chronic stress. Male mice underwent NMS from postnatal day 1–21 and as adults were assessed for open field behavior, hindpaw sensitivity, and visceromotor response (VMR to colorectal distension (CRD. VMR was also measured before and after treatment with intracolonic trinitrobenzene sulfonic acid (TNBS or exposure to acute or chronic water avoidance stress (WAS. Myeloperoxidase (MPO activity, proinflammatory gene and corticotropin-releasing factor (CRF receptor expression were measured in distal colon. Baseline VMR was not affected by NMS, but undergoing CRD increased anxiety-like behaviors and mechanical hindpaw sensitivity of NMS mice. Treatment with TNBS dose-dependently decreased body weight and survival only in NMS mice. Following TNBS treatment, IL-6 and artemin mRNA levels were decreased in the distal colon of NMS mice, despite increased MPO activity. A single WAS exposure increased VMR during CRD in NMS mice and increased IL-6 mRNA and CRF2 protein levels in the distal colon of naïve mice, whereas CRF2 protein levels were heightened in NMS colon both at baseline and post-WAS exposure. Taken together, these results suggest that NMS in mice disrupts inflammatory- and stress-induced gene expression in the colon, potentially contributing towards an exaggerated response to specific stressors later in life.

Ropivacaine and Bupivacaine prevent increased pain sensitivity without altering neuroimmune activation following repeated social defeat stress.

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Sawicki, Caroline M; Kim, January K; Weber, Michael D; Jarrett, Brant L; Godbout, Jonathan P; Sheridan, John F; Humeidan, Michelle

2018-03-01

Mounting evidence indicates that stress influences the experience of pain. Exposure to psychosocial stress disrupts bi-directional communication pathways between the central nervous system and peripheral immune system, and can exacerbate the frequency and severity of pain experienced by stressed subjects. Repeated social defeat (RSD) is a murine model of psychosocial stress that recapitulates the immune and behavioral responses to stress observed in humans, including activation of stress-reactive neurocircuitry and increased pro-inflammatory cytokine production. It is unclear, however, how these stress-induced neuroimmune responses contribute to increased pain sensitivity in mice exposed to RSD. Here we used a technique of regional analgesia with local anesthetics in mice to block the development of mechanical allodynia during RSD. We next investigated the degree to which pain blockade altered stress-induced neuroimmune activation and depressive-like behavior. Following development of a mouse model of regional analgesia with discrete sensory blockade over the dorsal-caudal aspect of the spine, C57BL/6 mice were divided into experimental groups and treated with Ropivacaine (0.08%), Liposomal Bupivacaine (0.08%), or Vehicle (0.9% NaCl) prior to exposure to stress. This specific region was selected for analgesia because it is the most frequent location for aggression-associated pain due to biting during RSD. Mechanical allodynia was assessed 12 h after the first, third, and sixth day of RSD after resolution of the sensory blockade. In a separate experiment, social avoidance behavior was determined after the sixth day of RSD. Blood, bone marrow, brain, and spinal cord were collected for immunological analyses after the last day of RSD in both experiments following behavioral assessments. RSD increased mechanical allodynia in an exposure-dependent manner that persisted for at least one week following cessation of the stressor. Mice treated with either Ropivacaine or

Consumption of NADPH for 2-HG Synthesis Increases Pentose Phosphate Pathway Flux and Sensitizes Cells to Oxidative Stress

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Susan J. Gelman

2018-01-01

Full Text Available Summary: Gain-of-function mutations in isocitrate dehydrogenase 1 (IDH1 occur in multiple types of human cancer. Here, we show that these mutations significantly disrupt NADPH homeostasis by consuming NADPH for 2-hydroxyglutarate (2-HG synthesis. Cells respond to 2-HG synthesis, but not exogenous administration of 2-HG, by increasing pentose phosphate pathway (PPP flux. We show that 2-HG production competes with reductive biosynthesis and the buffering of oxidative stress, processes that also require NADPH. IDH1 mutants have a decreased capacity to synthesize palmitate and an increased sensitivity to oxidative stress. Our results demonstrate that, even when NADPH is limiting, IDH1 mutants continue to synthesize 2-HG at the expense of other NADPH-requiring pathways that are essential for cell viability. Thus, rather than attempting to decrease 2-HG synthesis in the clinic, the consumption of NADPH by mutant IDH1 may be exploited as a metabolic weakness that sensitizes tumor cells to ionizing radiation, a commonly used anti-cancer therapy. : Using liquid chromatography/mass spectrometry (LC/MS and stable isotope tracing, Gelman et al. find that 2-HG production in cells with IDH1 mutations leads to increased pentose phosphate pathway activity to generate NADPH. Production of 2-HG competes with other NADPH-dependent pathways and sensitizes cells to redox stress. Keywords: 2-hydroxyglutarate, cancer metabolism, LC/MS, metabolomcis, pentose phosphate pathway, redox regulation

Altered olfactory processing of stress-related body odors and artificial odors in patients with panic disorder.

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Wintermann, Gloria-Beatrice; Donix, Markus; Joraschky, Peter; Gerber, Johannes; Petrowski, Katja

2013-01-01

Patients with Panic Disorder (PD) direct their attention towards potential threat, followed by panic attacks, and increased sweat production. Onés own anxiety sweat odor influences the attentional focus, and discrimination of threat or non-threat. Since olfactory projection areas overlap with neuronal areas of a panic-specific fear network, the present study investigated the neuronal processing of odors in general and of stress-related sweat odors in particular in patients with PD. A sample of 13 patients with PD with/ without agoraphobia and 13 age- and gender-matched healthy controls underwent an fMRI investigation during olfactory stimulation with their stress-related sweat odors (TSST, ergometry) as well as artificial odors (peach, artificial sweat) as non-fearful non-body odors. The two groups did not differ with respect to their olfactory identification ability. Independent of the kind of odor, the patients with PD showed activations in fronto-cortical areas in contrast to the healthy controls who showed activations in olfaction-related areas such as the amygdalae and the hippocampus. For artificial odors, the patients with PD showed a decreased neuronal activation of the thalamus, the posterior cingulate cortex and the anterior cingulate cortex. Under the presentation of sweat odor caused by ergometric exercise, the patients with PD showed an increased activation in the superior temporal gyrus, the supramarginal gyrus, and the cingulate cortex which was positively correlated with the severity of the psychopathology. For the sweat odor from the anxiety condition, the patients with PD showed an increased activation in the gyrus frontalis inferior, which was positively correlated with the severity of the psychopathology. The results suggest altered neuronal processing of olfactory stimuli in PD. Both artificial odors and stress-related body odors activate specific parts of a fear-network which is associated with an increased severity of the psychopathology.

Altered olfactory processing of stress-related body odors and artificial odors in patients with panic disorder.

Directory of Open Access Journals (Sweden)

Gloria-Beatrice Wintermann

Full Text Available Patients with Panic Disorder (PD direct their attention towards potential threat, followed by panic attacks, and increased sweat production. Onés own anxiety sweat odor influences the attentional focus, and discrimination of threat or non-threat. Since olfactory projection areas overlap with neuronal areas of a panic-specific fear network, the present study investigated the neuronal processing of odors in general and of stress-related sweat odors in particular in patients with PD.A sample of 13 patients with PD with/ without agoraphobia and 13 age- and gender-matched healthy controls underwent an fMRI investigation during olfactory stimulation with their stress-related sweat odors (TSST, ergometry as well as artificial odors (peach, artificial sweat as non-fearful non-body odors.The two groups did not differ with respect to their olfactory identification ability. Independent of the kind of odor, the patients with PD showed activations in fronto-cortical areas in contrast to the healthy controls who showed activations in olfaction-related areas such as the amygdalae and the hippocampus. For artificial odors, the patients with PD showed a decreased neuronal activation of the thalamus, the posterior cingulate cortex and the anterior cingulate cortex. Under the presentation of sweat odor caused by ergometric exercise, the patients with PD showed an increased activation in the superior temporal gyrus, the supramarginal gyrus, and the cingulate cortex which was positively correlated with the severity of the psychopathology. For the sweat odor from the anxiety condition, the patients with PD showed an increased activation in the gyrus frontalis inferior, which was positively correlated with the severity of the psychopathology.The results suggest altered neuronal processing of olfactory stimuli in PD. Both artificial odors and stress-related body odors activate specific parts of a fear-network which is associated with an increased severity of the

Age-Related Decrease in Heat Shock 70-kDa Protein 8 in Cerebrospinal Fluid Is Associated with Increased Oxidative Stress.

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Loeffler, David A; Klaver, Andrea C; Coffey, Mary P; Aasly, Jan O; LeWitt, Peter A

2016-01-01

Age-associated declines in protein homeostasis mechanisms ("proteostasis") are thought to contribute to age-related neurodegenerative disorders. The increased oxidative stress which occurs with aging can activate a key proteostatic process, chaperone-mediated autophagy. This study investigated age-related alteration in cerebrospinal fluid (CSF) concentrations of heat shock 70-kDa protein 8 (HSPA8), a molecular chaperone involved in proteostatic mechanisms including chaperone-mediated autophagy, and its associations with indicators of oxidative stress (8-hydroxy-2'-deoxyguanosine [8-OHdG] and 8-isoprostane) and total anti-oxidant capacity. We examined correlations between age, HSPA8, 8-OHdG, 8-isoprostane, and total antioxidant capacity (TAC) in CSF samples from 34 healthy subjects ranging from 20 to 75 years of age. Age was negatively associated with HSPA8 (ρ = -0.47; p = 0.005). An age-related increase in oxidative stress was indicated by a positive association between age and 8-OHdG (ρ = 0.61; p = 0.0001). HSPA8 was moderately negatively associated with 8-OHdG (ρ = -0.58; p = 0.0004). Age and HSPA8 were weakly associated with 8-isoprostane and TAC (range of ρ values: -0.15 to 0.16). Our findings in this exploratory study suggest that during healthy aging, CSF HSPA8 may decrease, perhaps due in part to an increase in oxidative stress. Our results also suggest that 8-OHdG may be more sensitive than 8-isoprostane for measuring oxidative stress in CSF. Further studies are indicated to determine if our findings can be replicated with a larger cohort, and if the age-related decrease in HSPA8 in CSF is reflected by a similar change in the brain.

Radiative processes for Rindler and accelerating observers and the stress-tensor detector

International Nuclear Information System (INIS)

Paola, R. De; Svaiter, N.F.

1996-04-01

It is considered a monopole detector interacting with a massive scalar field. Using the rotating wave approximation the radiative processes is discussed from the accelerated frame point of view. After this, it is obtained the Minkowski vacuum stress tensor measured by the accelerated observer using a non-gravitational stress sensor detector. Finally we analyse radiative processes of the monopole detector travelling in a world line that is inertial in the infinite past and has a constant proper acceleration in the infinite future. (author). 30 refs

Using normalisation process theory to understand barriers and facilitators to implementing mindfulness-based stress reduction for people with multiple sclerosis.

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Simpson, Robert; Simpson, Sharon; Wood, Karen; Mercer, Stewart W; Mair, Frances S

2018-01-01

Objectives To study barriers and facilitators to implementation of mindfulness-based stress reduction for people with multiple sclerosis. Methods Qualitative interviews were used to explore barriers and facilitators to implementation of mindfulness-based stress reduction, including 33 people with multiple sclerosis, 6 multiple sclerosis clinicians and 2 course instructors. Normalisation process theory provided the underpinning conceptual framework. Data were analysed deductively using normalisation process theory constructs (coherence, cognitive participation, collective action and reflexive monitoring). Results Key barriers included mismatched stakeholder expectations, lack of knowledge about mindfulness-based stress reduction, high levels of comorbidity and disability and skepticism about embedding mindfulness-based stress reduction in routine multiple sclerosis care. Facilitators to implementation included introducing a pre-course orientation session; adaptations to mindfulness-based stress reduction to accommodate comorbidity and disability and participants suggested smaller, shorter classes, shortened practices, exclusion of mindful-walking and more time with peers. Post-mindfulness-based stress reduction booster sessions may be required, and objective and subjective reports of benefit would increase clinician confidence in mindfulness-based stress reduction. Discussion Multiple sclerosis patients and clinicians know little about mindfulness-based stress reduction. Mismatched expectations are a barrier to participation, as is rigid application of mindfulness-based stress reduction in the context of disability. Course adaptations in response to patient needs would facilitate uptake and utilisation. Rendering access to mindfulness-based stress reduction rapid and flexible could facilitate implementation. Embedded outcome assessment is desirable.

When bad stress goes good: increased threat reactivity predicts improved category learning performance.

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Ell, Shawn W; Cosley, Brandon; McCoy, Shannon K

2011-02-01

The way in which we respond to everyday stressors can have a profound impact on cognitive functioning. Maladaptive stress responses in particular are generally associated with impaired cognitive performance. We argue, however, that the cognitive system mediating task performance is also a critical determinant of the stress-cognition relationship. Consistent with this prediction, we observed that stress reactivity consistent with a maladaptive, threat response differentially predicted performance on two categorization tasks. Increased threat reactivity predicted enhanced performance on an information-integration task (i.e., learning is thought to depend upon a procedural-based memory system), and a (nonsignificant) trend for impaired performance on a rule-based task (i.e., learning is thought to depend upon a hypothesis-testing system). These data suggest that it is critical to consider both variability in the stress response and variability in the cognitive system mediating task performance in order to fully understand the stress-cognition relationship.

Chemical stress induced by heliotrope (Heliotropium europaeum L.) allelochemicals and increased activity of antioxidant enzymes.

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Abdulghader, Kalantar; Nojavan, Majid; Naghshbandi, Nabat

2008-03-15

The aims of this study were to evaluate the allelopathic potential of heliotrope on some biochemical processes of dodder. The preliminary experiments revealed that the effect of aqueous extract of leaves of heliotrope is higher than its seeds and roots. So, the aqueous extract of leaves was used in remaining experiments. Leaf extracts of 5 g powder per 100 mL H2O inhibited the germination of dodder seeds up to 95% and that of radish up to 100%. While, the aqueous extract of vine leaves which is a non-allelopathic plant did not have any inhibitory effect on these seeds. Vine leaf was used as a control to show that the inhibitory effect of heliotrope is due to an inhibitory compound but not due to the concentration. The leaf extract of heliotrope at 0.0, 0.1, 1.0, 2, 3, 4 and 5 g powder per 100 mL H2O reduced the radish seedling growth from 14 cm to about 0.5 cm and that of dodder from 7.5 cm to about 0.25 cm. The effects of heliotrope allelochemicals on some physiological and biochemical processes of radish was also Investigated. The activity of auxin oxidase increased in leaves and roots of radish. Suggesting that the reduced radish growth is due to the decreased active auxin levels in its leaves and roots. The activity of alpha-amylase was reduced, so reduction of starch degradation and lack of respiratory energy is the prime reason of germination inhibition in dodder and radish seeds. The level of soluble sugars increased. This is an indication of reduction of the activity of some respiratory enzymes and reduced consumption of these sugars. Proline levels were also increased, indicating that, the chemical stress is induced by leaf extract. Finally, the activities of GPX and CAT which are antioxidant enzymes were increased, along with increased extract concentration. These finding shows that the chemical stress induced by leaf extract produces super oxide (O2*) and H2O2, which is neutralized to H2O and O2 by these enzymes.

Variation behavior of residual stress distribution by manufacturing processes in welded pipes of austenitic stainless steel

International Nuclear Information System (INIS)

Ihara, Ryohei; Hashimoto, Tadafumi; Mochizuki, Masahito

2012-01-01

Stress corrosion cracking (SCC) has been observed near heat affected zone (HAZ) of primary loop recirculation pipes made of low-carbon austenitic stainless steel type 316L in the nuclear power plants. For the non-sensitization material, residual stress is the important factor of SCC, and it is generated by machining and welding. In the actual plants, welding is conducted after machining as manufacturing processes of welded pipes. It could be considered that residual stress generated by machining is varied by welding as a posterior process. This paper presents residual stress variation due to manufacturing processes of pipes using X-ray diffraction method. Residual stress distribution due to welding after machining had a local maximum stress in HAZ. Moreover, this value was higher than residual stress generated by welding or machining. Vickers hardness also had a local maximum hardness in HAZ. In order to clarify hardness variation, crystal orientation analysis with EBSD method was performed. Recovery and recrystallization were occurred by welding heat near the weld metal. These lead hardness decrease. The local maximum region showed no microstructure evolution. In this region, machined layer was remained. Therefore, the local maximum hardness was generated at machined layer. The local maximum stress was caused by the superposition effect of residual stress distributions due to machining and welding. Moreover, these local maximum residual stress and hardness are exceeded critical value of SCC initiation. In order to clarify the effect of residual stress on SCC initiation, evaluation including manufacturing processes is important. (author)

Effects on residual stresses of aluminum alloy LC4 by laser shock processing

Science.gov (United States)

Zhang, Yong-kang; Lu, Jin-zhong; Kong, De-jun; Yao, Hui-xue; Yang, Chao-jun

2007-12-01

The influences of processing parameters on laser-induced shock waves in metal components are discussed and analyzed. The effects of different parameters of laser shock processing (LSP) on residual stress of aerospace aluminum alloy LC4 were investigated. LSP was performed by using an Nd: glass phosphate laser with 23 ns pulse width and up to ~45 J pulse energy at power densities above GW/mm -2. Special attention is paid to the residual stresses from laser shock processing. Modification of microstructure, surface morphology by laser shock processing is also discussed. Results to date indicate that laser shock processing has great potential as a means of improving the mechanical performance of components.

Increase in Operator's Sympathetic Nerve Activity during Complicated Hepatobiliary Surgery: Evidence for Surgeons' Mental Stress.

Science.gov (United States)

Yamanouchi, Kosho; Hayashida, Naomi; Kuba, Sayaka; Sakimura, Chika; Kuroki, Tamotsu; Togo, Michita; Katayama, Noritada; Takamura, Noboru; Eguchi, Susumu

2015-11-01

Surgeons often experience stress during operations. The heart rate variability (HRV) is the variability in the beat-to-beat interval, which has been used as parameters of stress. The purpose of this study was to evaluate mental stress of surgeons before, during and after operations, especially during pancreaticoduodenectomy (PD) and living donor liver transplantation (LDLT). Additionally, the parameters were compared in various procedures during the operations. By frequency domain method using electrocardiograph, we measured the high frequency (HF) component, representing the parasympathetic activity, and the low frequency (LF)/HF ratio, representing the sympathetic activity. In all 5 cases of PD, the surgeon showed significantly lower HF component and higher LF/HF during operation, indicating predominance of sympathetic nervous system and increased stress, than those before the operation (p operation. Out of the 4 LDLT cases, the value of HF was decreased in two and the LF/HF increased in three cases (p operation compared to those before the operation. In all cases, the value of HF was decreased and/or the LF/HF increased significantly during the reconstruction of the vessels or bile ducts than during the removal of the liver. Thus, sympathetic nerve activity increased during hepatobiliary surgery compared with the level before the operation, and various procedures during the operations induced diverse changes in the autonomic nervous activities. The HRV analysis could assess the chronological changes of mental stress by measuring the autonomic nervous balances.

Nivalenol induces oxidative stress and increases deoxynivalenol pro-oxidant effect in intestinal epithelial cells

Energy Technology Data Exchange (ETDEWEB)

Del Regno, Marisanta; Adesso, Simona; Popolo, Ada [Department of Pharmacy, School of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132–84084 Fisciano, Salerno (Italy); Quaroni, Andrea [Department of Biomedical Sciences, Cornell University, Veterinary Research Tower, Cornell University, Ithaca, NY 14853–6401 (United States); Autore, Giuseppina [Department of Pharmacy, School of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132–84084 Fisciano, Salerno (Italy); Severino, Lorella [Department of Pathology and Animal Health, Division of Toxicology, School of Veterinary Medicine, University of Naples “Federico II”, Via Delpino 1, 80137 Naples (Italy); Marzocco, Stefania, E-mail: smarzocco@unisa.it [Department of Pharmacy, School of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132–84084 Fisciano, Salerno (Italy)

2015-06-01

Mycotoxins are secondary fungal metabolites often found as contaminants in almost all agricultural commodities worldwide, and the consumption of food or feed contaminated by mycotoxins represents a major risk for human and animal health. Reactive oxygen species are normal products of cellular metabolism. However, disproportionate generation of reactive oxygen species poses a serious problem to bodily homeostasis and causes oxidative tissue damage. In this study we analyzed the effect of two trichothecenes mycotoxins: nivalenol and deoxynivalenol, alone and in combination, on oxidative stress in the non-tumorigenic intestinal epithelial cell line IEC-6. Our results indicate the pro-oxidant nivalenol effect in IEC-6, the stronger pro-oxidant effect of nivalenol when compared to deoxynivalenol and, interestingly, that nivalenol increases deoxynivalenol pro-oxidative effects. Mechanistic studies indicate that the observed effects were mediated by NADPH oxidase, calcium homeostasis alteration, NF-kB and Nrf2 pathways activation and by iNOS and nitrotyrosine formation. The toxicological interaction by nivalenol and deoxynivalenol reported in this study in IEC-6, points out the importance of the toxic effect of these mycotoxins, mostly in combination, further highlighting the risk assessment process of these toxins that are of growing concern. - Highlights: • Nivalenol induces oxidative stress in intestinal epithelial cells (IECs). • Nivalenol increases deoxynivalenol pro-oxidant effects in IECs. • Nivalenol and deoxynivalenol trigger antioxidant response IECs. • These results indicate the importance of mycotoxins co-contamination.

Good stress, bad stress and oxidative stress: insights from anticipatory cortisol reactivity.

Science.gov (United States)

Aschbacher, Kirstin; O'Donovan, Aoife; Wolkowitz, Owen M; Dhabhar, Firdaus S; Su, Yali; Epel, Elissa

2013-09-01

Chronic psychological stress appears to accelerate biological aging, and oxidative damage is an important potential mediator of this process. However, the mechanisms by which psychological stress promotes oxidative damage are poorly understood. This study investigates the theory that cortisol increases in response to an acutely stressful event have the potential to either enhance or undermine psychobiological resilience to oxidative damage, depending on the body's prior exposure to chronic psychological stress. In order to achieve a range of chronic stress exposure, forty-eight post-menopausal women were recruited in a case-control design that matched women caring for spouses with dementia (a chronic stress model) with similarly aged control women whose spouses were healthy. Participants completed a questionnaire assessing perceived stress over the previous month and provided fasting blood. Three markers of oxidative damage were assessed: 8-iso-prostaglandin F(2α) (IsoP), lipid peroxidation, 8-hydroxyguanosine (8-oxoG) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), reflecting oxidative damage to RNA/DNA respectively. Within approximately one week, participants completed a standardized acute laboratory stress task while salivary cortisol responses were measured. The increase from 0 to 30 min was defined as "peak" cortisol reactivity, while the increase from 0 to 15 min was defined as "anticipatory" cortisol reactivity, representing a cortisol response that began while preparing for the stress task. Women under chronic stress had higher 8-oxoG, oxidative damage to RNA (pstress and elevated oxidative stress damage, but only among women under chronic stress. Consistent with this model, bootstrapped path analysis found significant indirect paths from perceived stress to 8-oxoG and IsoP (but not 8-OHdG) via anticipatory cortisol reactivity, showing the expected relations among chronically stressed participants (p≤.01) Intriguingly, among those with low chronic stress

Stress analysis and optimization of Nd:YAG pulsed laser processing of notches for fracture splitting of a C70S6 connecting rod

International Nuclear Information System (INIS)

Kou, Shuqing; Gao, Yan; Zhao, Yong; Lin, Baojun

2017-01-01

The pulsed laser pre-processing of a notch as the fracture initiation source for the splitting process is the key mechanism of an advanced fracture splitting technology for C70S6 connecting rods. This study investigated the stress field of Nd:YAG pulsed laser grooving, which affects the rapid fracture initiation at the notch root and the controlled crack extension in the critical fracture splitting quality, to improve manufacturing quality. Thermal elastic-plastic incremental theory was applied to build the finite element analysis model of the stress field of pulsed laser grooving for fracture splitting based on the Rotary-Gauss body heat source. The corresponding numerical simulation of the stress field was conducted. The changes and distributions of the stress during pulsed laser grooving were examined, the influence rule of the primary technological parameters on the residual stress was analyzed, and the analysis results were validated by the corresponding cutting experiment. Results showed that the residual stress distribution was concentrated in the Heat-affected zone (HAZ) near the fracture splitting notch, which would cause micro-cracks in the HAZ. The stress state of the notch root in the fracture initiation direction was tensile stress, which was beneficial to the fracture initiation and the crack rapid extension in the subsequent fracture splitting process. However, the uneven distribution of the stress could lead to fracture splitting defects, and thus the residual stress should be lowered to a reasonable range. Decreasing the laser pulse power, increasing the processing speed, and lowering the pulse width can lower the residual stress. Along with the actual production, the reasonable main technological parameters were obtained.

Stress analysis and optimization of Nd:YAG pulsed laser processing of notches for fracture splitting of a C70S6 connecting rod

Energy Technology Data Exchange (ETDEWEB)

Kou, Shuqing; Gao, Yan; Zhao, Yong; Lin, Baojun [Jilin University, Changchun (China)

2017-05-15

The pulsed laser pre-processing of a notch as the fracture initiation source for the splitting process is the key mechanism of an advanced fracture splitting technology for C70S6 connecting rods. This study investigated the stress field of Nd:YAG pulsed laser grooving, which affects the rapid fracture initiation at the notch root and the controlled crack extension in the critical fracture splitting quality, to improve manufacturing quality. Thermal elastic-plastic incremental theory was applied to build the finite element analysis model of the stress field of pulsed laser grooving for fracture splitting based on the Rotary-Gauss body heat source. The corresponding numerical simulation of the stress field was conducted. The changes and distributions of the stress during pulsed laser grooving were examined, the influence rule of the primary technological parameters on the residual stress was analyzed, and the analysis results were validated by the corresponding cutting experiment. Results showed that the residual stress distribution was concentrated in the Heat-affected zone (HAZ) near the fracture splitting notch, which would cause micro-cracks in the HAZ. The stress state of the notch root in the fracture initiation direction was tensile stress, which was beneficial to the fracture initiation and the crack rapid extension in the subsequent fracture splitting process. However, the uneven distribution of the stress could lead to fracture splitting defects, and thus the residual stress should be lowered to a reasonable range. Decreasing the laser pulse power, increasing the processing speed, and lowering the pulse width can lower the residual stress. Along with the actual production, the reasonable main technological parameters were obtained.

A self-medication hypothesis for increased vulnerability to drug abuse in prenatally restraint stressed rats.

Science.gov (United States)

Reynaert, Marie-Line; Marrocco, Jordan; Gatta, Eleonora; Mairesse, Jérôme; Van Camp, Gilles; Fagioli, Francesca; Maccari, Stefania; Nicoletti, Ferdinando; Morley-Fletcher, Sara

Stress-related events that occur in the perinatal period can permanently change brain and behavior of the developing individual and there is increasing evidence that early-life adversity is a contributing factor in the etiology of drug abuse and mood disorders. Neural adaptations resulting from early-life stress may mediate individual differences in novelty responsiveness and in turn contribute to drug abuse vulnerability. Prenatal restraint stress (PRS) in rats is a well-documented model of early stress known to induce long-lasting neurobiological and behavioral alterations including impaired feedback mechanisms of the HPA axis, enhanced novelty seeking, and increased sensitiveness to psychostimulants as well as anxiety/depression-like behavior. Together with the HPA axis, functional alterations of the mesolimbic dopamine system and of the metabotropic glutamate receptors system appear to be involved in the addiction-like profile of PRS rats.

Can stress increase Alzheimer's disease risk in women?

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Johansson, Lena

2014-02-01

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the accumulation of β-amyloid peptides and neurofibrilllary tangles in brain, resulting in neuronal death and loss of cognitive abilities. It has been hypothesized that longstanding psychological stress can result in neural degeneration and AD due to pathological alterations in the hypothalamic-pituitary-adrenal axis. In recent years several epidemiological studies been published on stress as a risk factor for AD. As women are more likely to suffer from stress-related psychiatric disorders, such as post-traumatic stress disorder and clinical burnout syndrome, special effort has been made according to the gender differences in risk of AD. However, few studies have stratified for gender, due to small sample sizes and limited statistic power, and no reliable findings have been found. Additional longitudinal studies are therefore needed for studying gender differences and for determining what mediates the stress and AD association, in both genders.

Licensing process for the power increase

International Nuclear Information System (INIS)

Perez P, R.; Mamani A, Y.R.; Salgado G, J.R.

2006-01-01

The licensing process for the power increase of a nuclear power station is presented, this includes the description of the effective normative framework, the attributions of the one Mexican regulator organism in nuclear matter, the definition and importance of the power level of a nuclear reactor for the safety studies. Also, the types of power increase according to its magnitude, and the regulator process that it includes the scope and the detail of the required information that it should be evaluated by the one regulator organism are discussed. Finally it offers a summary of the experience that one has in Mexico for this type of processes. (Author)

Effect of an absorbent overlay on the residual stress field induced by laser shock processing on aluminum samples

International Nuclear Information System (INIS)

Rubio-Gonzalez, C.; Gomez-Rosas, G.; Ocana, J.L.; Molpeceres, C.; Banderas, A.; Porro, J.; Morales, M.

2006-01-01

Laser shock processing (LSP) or laser shock peening is a new technique for strengthening metals. This process induces a compressive residual stress field, which increases fatigue crack initiation life and reduces fatigue crack growth rate. Specimens of 6061-T6 aluminum alloy are used in this investigation. A convergent lens is used to deliver 2.5 J, 8 ns laser pulses by a Q-switch Nd:YAG laser, operating at 10 Hz. The pulses are focused to a diameter of 1.5 mm onto aluminum samples. Density of 2500 pulses/cm 2 with infrared (1064 nm) radiation was used. The effect of an absorbent overlay on the residual stress field using this LSP setup and this energy level is evaluated. Residual stress distribution as a function of depth is assessed by the hole drilling method. It is observed that the overlay makes the compressive residual stress profile move to the surface. This effect is explained on the basis of the vaporization of the coat layer suppressing thermal effects on the metallic substrate. The effect of coating the specimen surface before LSP treatment may have advantages on improving wear and contact fatigue properties of this aluminum alloy

Subchronic mild noise stress increases HRP permeability in rat small intestine in vitro.

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Bijlsma, P B; van Raaij, M T; Dobbe, C J; Timmerman, A; Kiliaan, A J; Taminiau, J A; Groot, J A

2001-05-01

Recently we reported an increased trans- and paracellular protein permeability in rat small intestine after acute cold restraint stress. In the present study, we applied randomized 95- or 105-dB white noise pulses during 45 min/h, 12 h/day, duration 8 days, as a milder, but more chronic stressor to male rats. At 8 days before the noise experiments, 50% of the animals were cannulated in the vena cava for blood sampling during the experimental period. The other 50% of the animals were sacrificed at Day 9, segments of ileum were mounted in Ussing chambers and perfused at 37 degrees C. Horseradish peroxidase (HRP) was added mucosally, serosal appearance was detected enzymatically and tissues were fixed for electron microscopy. In the animals exposed to 95-dB noise, plasma corticosterone levels were enhanced twofold compared to controls, and ileal HRP flux was enhanced twofold. Electron micrographs of tissue from stressed or control animals showed no detectable paracellular staining of HRP. Quantification of HRP-containing endosomes in enterocytes revealed a twofold increase in endosome number in the animals exposed to 95-db noise indicating that the increased HRP permeability was primarily due to increased endocytosis. In contrast to the animals exposed to 95-dB noise, rats exposed to 105-dB noise showed no increase in corticosterone levels and ileal HRP fluxes were not significantly different from controls. We conclude that mild subchronic noise stress may cause a decrease in intestinal barrier function by increased transcytosis of luminal antigens.

Short-term stress enhances cellular immunity and increases early resistance to squamous cell carcinoma.

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Dhabhar, Firdaus S; Saul, Alison N; Daugherty, Christine; Holmes, Tyson H; Bouley, Donna M; Oberyszyn, Tatiana M

2010-01-01

In contrast to chronic/long-term stress that suppresses/dysregulates immune function, an acute/short-term fight-or-flight stress response experienced during immune activation can enhance innate and adaptive immunity. Moderate ultraviolet-B (UV) exposure provides a non-invasive system for studying the naturalistic emergence, progression and regression of squamous cell carcinoma (SCC). Because SCC is an immunoresponsive cancer, we hypothesized that short-term stress experienced before UV exposure would enhance protective immunity and increase resistance to SCC. Control and short-term stress groups were treated identically except that the short-term stress group was restrained (2.5h) before each of nine UV-exposure sessions (minimum erythemal dose, 3-times/week) during weeks 4-6 of the 10-week UV exposure protocol. Tumors were measured weekly, and tissue collected at weeks 7, 20, and 32. Chemokine and cytokine gene expression was quantified by real-time PCR, and CD4+ and CD8+ T cells by flow cytometry and immunohistochemistry. Compared to controls, the short-term stress group showed greater cutaneous T-cell attracting chemokine (CTACK)/CCL27, RANTES, IL-12, and IFN-gamma gene expression at weeks 7, 20, and 32, higher skin infiltrating T cell numbers (weeks 7 and 20), lower tumor incidence (weeks 11-20) and fewer tumors (weeks 11-26). These results suggest that activation of short-term stress physiology increased chemokine expression and T cell trafficking and/or function during/following UV exposure, and enhanced Type 1 cytokine-driven cell-mediated immunity that is crucial for resistance to SCC. Therefore, the physiological fight-or-flight stress response and its adjuvant-like immuno-enhancing effects, may provide a novel and important mechanism for enhancing immune system mediated tumor-detection/elimination that merits further investigation.

Increased Oxidative Stress and Mitochondrial Dysfunction in Zucker Diabetic Rat Liver and Brain

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Haider Raza

2015-02-01

Full Text Available Background/Aims: The Zucker diabetic fatty (ZDF, FA/FA rat is a genetic model of type 2 diabetes, characterized by insulin resistance with progressive metabolic syndrome. We have previously demonstrated mitochondrial dysfunction and oxidative stress in the heart, kidneys and pancreas of ZDF rats. However, the precise molecular mechanism of disease progression is not clear. Our aim in the present study was to investigate oxidative stress and mitochondrial dysfunction in the liver and brain of ZDF rats. Methods: In this study, we have measured mitochondrial oxidative stress, bioenergetics and redox homeostasis in the liver and brain of ZDF rats. Results: Our results showed increased reactive oxygen species (ROS production in the ZDF rat brain compared to the liver, while nitric oxide (NO production was markedly increased both in the brain and liver. High levels of lipid and protein peroxidation were also observed in these tissues. Glutathione metabolism and mitochondrial respiratory functions were adversely affected in ZDF rats when compared to Zucker lean (ZL, +/FA control rats. Reduced ATP synthesis was also observed in the liver and brain of ZDF rats. Western blot analysis confirmed altered expression of cytochrome P450 2E1, iNOS, p-JNK, and IκB-a confirming an increase in oxidative and metabolic stress in ZDF rat tissues. Conclusions: Our data shows that, like other tissues, ZDF rat liver and brain develop complications associated with redox homeostasis and mitochondrial dysfunction. These results, thus, might have implications in understanding the etiology and pathophysiology of diabesity which in turn, would help in managing the disease associated complications.

Increased oxidative stress and antioxidant expression in mouse keratinocytes following exposure to paraquat

International Nuclear Information System (INIS)

Black, Adrienne T.; Gray, Joshua P.; Shakarjian, Michael P.; Laskin, Debra L.; Heck, Diane E.; Laskin, Jeffrey D.

2008-01-01

Paraquat (1,1'-dimethyl-4,4'-bipyridinium) is a widely used herbicide known to induce skin toxicity. This is thought to be due to oxidative stress resulting from the generation of cytotoxic reactive oxygen intermediates (ROI) during paraquat redox cycling. The skin contains a diverse array of antioxidant enzymes which protect against oxidative stress including superoxide dismutase (SOD), catalase, glutathione peroxidase-1 (GPx-1), heme oxygenase-1 (HO-1), metallothionein-2 (MT-2), and glutathione-S-transferases (GST). In the present studies we compared paraquat redox cycling in primary cultures of undifferentiated and differentiated mouse keratinocytes and determined if this was associated with oxidative stress and altered expression of antioxidant enzymes. We found that paraquat readily undergoes redox cycling in both undifferentiated and differentiated keratinocytes, generating superoxide anion and hydrogen peroxide as well as increased protein oxidation which was greater in differentiated cells. Paraquat treatment also resulted in increased expression of HO-1, Cu,Zn-SOD, catalase, GSTP1, GSTA3 and GSTA4. However, no major differences in expression of these enzymes were evident between undifferentiated and differentiated cells. In contrast, expression of GSTA1-2 was significantly greater in differentiated relative to undifferentiated cells after paraquat treatment. No changes in expression of MT-2, Mn-SOD, GPx-1, GSTM1 or the microsomal GST's mGST1, mGST2 and mGST3, were observed in response to paraquat. These data demonstrate that paraquat induces oxidative stress in keratinocytes leading to increased expression of antioxidant genes. These intracellular proteins may be important in protecting the skin from paraquat-mediated cytotoxicity

Type 2 diabetes mellitus induces congenital heart defects in murine embryos by increasing oxidative stress, endoplasmic reticulum stress, and apoptosis.

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Wu, Yanqing; Reece, E Albert; Zhong, Jianxiang; Dong, Daoyin; Shen, Wei-Bin; Harman, Christopher R; Yang, Peixin

2016-09-01

Maternal type 1 and 2 diabetes mellitus are strongly associated with high rates of severe structural birth defects, including congenital heart defects. Studies in type 1 diabetic embryopathy animal models have demonstrated that cellular stress-induced apoptosis mediates the teratogenicity of maternal diabetes leading to congenital heart defect formation. However, the mechanisms underlying maternal type 2 diabetes mellitus-induced congenital heart defects remain largely unknown. We aim to determine whether oxidative stress, endoplasmic reticulum stress, and excessive apoptosis are the intracellular molecular mechanisms underlying maternal type 2 diabetes mellitus-induced congenital heart defects. A mouse model of maternal type 2 diabetes mellitus was established by feeding female mice a high-fat diet (60% fat). After 15 weeks on the high-fat diet, the mice showed characteristics of maternal type 2 diabetes mellitus. Control dams were either fed a normal diet (10% fat) or the high-fat diet during pregnancy only. Female mice from the high-fat diet group and the 2 control groups were mated with male mice that were fed a normal diet. At E12.5, embryonic hearts were harvested to determine the levels of lipid peroxides and superoxide, endoplasmic reticulum stress markers, cleaved caspase 3 and 8, and apoptosis. E17.5 embryonic hearts were harvested for the detection of congenital heart defect formation using India ink vessel patterning and histological examination. Maternal type 2 diabetes mellitus significantly induced ventricular septal defects and persistent truncus arteriosus in the developing heart, along with increasing oxidative stress markers, including superoxide and lipid peroxidation; endoplasmic reticulum stress markers, including protein levels of phosphorylated-protein kinase RNA-like endoplasmic reticulum kinase, phosphorylated-IRE1α, phosphorylated-eIF2α, C/EBP homologous protein, and binding immunoglobulin protein; endoplasmic reticulum chaperone gene

Persistent Increase in Microglial RAGE Contributes to Chronic Stress-Induced Priming of Depressive-like Behavior.

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Franklin, Tina C; Wohleb, Eric S; Zhang, Yi; Fogaça, Manoela; Hare, Brendan; Duman, Ronald S

2018-01-01

Chronic stress-induced inflammatory responses occur in part via danger-associated molecular pattern (DAMP) molecules, such as high mobility group box 1 protein (HMGB1), but the receptor(s) underlying DAMP signaling have not been identified. Microglia morphology and DAMP signaling in enriched rat hippocampal microglia were examined during the development and expression of chronic unpredictable stress (CUS)-induced behavioral deficits, including long-term, persistent changes after CUS. The results show that CUS promotes significant morphological changes and causes robust upregulation of HMGB1 messenger RNA in enriched hippocampal microglia, an effect that persists for up to 6 weeks after CUS exposure. This coincides with robust and persistent upregulation of receptor for advanced glycation end products (RAGE) messenger RNA, but not toll-like receptor 4 in hippocampal microglia. CUS also increased surface expression of RAGE protein on hippocampal microglia as determined by flow cytometry and returned to basal levels 5 weeks after CUS. Importantly, exposure to short-term stress was sufficient to increase RAGE surface expression as well as anhedonic behavior, reflecting a primed state that results from a persistent increase in RAGE messenger RNA expression. Further evidence for DAMP signaling in behavioral responses is provided by evidence that HMGB1 infusion into the hippocampus was sufficient to cause anhedonic behavior and by evidence that RAGE knockout mice were resilient to stress-induced anhedonia. Together, the results provide evidence of persistent microglial HMGB1-RAGE expression that increases vulnerability to depressive-like behaviors long after chronic stress exposure. Copyright © 2017 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Mechanisms of food processing and storage-related stress tolerance in Clostridium botulinum.

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Dahlsten, Elias; Lindström, Miia; Korkeala, Hannu

2015-05-01

Vegetative cultures of Clostridium botulinum produce the extremely potent botulinum neurotoxin, and may jeopardize the safety of foods unless sufficient measures to prevent growth are applied. Minimal food processing relies on combinations of mild treatments, primarily to avoid deterioration of the sensory qualities of the food. Tolerance of C. botulinum to minimal food processing is well characterized. However, data on effects of successive treatments on robustness towards further processing is lacking. Developments in genetic manipulation tools and the availability of annotated genomes have allowed identification of genetic mechanisms involved in stress tolerance of C. botulinum. Most studies focused on low temperature, and the importance of various regulatory mechanisms in cold tolerance of C. botulinum has been demonstrated. Furthermore, novel roles in cold tolerance were shown for metabolic pathways under the control of these regulators. A role for secondary oxidative stress in tolerance to extreme temperatures has been proposed. Additionally, genetic mechanisms related to tolerance to heat, low pH, and high salinity have been characterized. Data on genetic stress-related mechanisms of psychrotrophic Group II C. botulinum strains are scarce; these mechanisms are of interest for food safety research and should thus be investigated. This minireview encompasses the importance of C. botulinum as a food safety hazard and its central physiological characteristics related to food-processing and storage-related stress. Special attention is given to recent findings considering genetic mechanisms C. botulinum utilizes in detecting and countering these adverse conditions. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Finnish physicians' stress related to information systems keeps increasing: a longitudinal three-wave survey study.

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Heponiemi, Tarja; Hyppönen, Hannele; Vehko, Tuulikki; Kujala, Sari; Aalto, Anna-Mari; Vänskä, Jukka; Elovainio, Marko

2017-10-17

Poorly functioning, time-consuming, and inadequate information systems are among the most important work-related psychosocial factors causing stress in physicians. The present study examined the trend in the perceived stress that was related to information systems (SRIS) among Finnish physicians during a nine-year follow-up. In addition, we examined the associations of gender, age, employment sector, specialization status, leadership position, on-call burden, and time pressure with SRIS change and levels. A longitudinal design with three survey data collection waves (2006, 2010 and 2015) based on a random sample of Finnish physicians in 2006 was used. The study sample included 1095 physicians (62.3% women, mean age 54.4 years) who provided data on SRIS in every wave. GLM repeated measures analyses were used to examine the associations between independent variables and the SRIS trend during the years 2006, 2010, and 2015. SRIS increased during the study period. The estimated marginal mean of SRIS in 2006 was 2.80 (95% CI = 2.68-2.92) and the mean increase was 0.46 (95% CI = 0.30-0.61) points from 2006 to 2010 and 0.25 (95% CI = 0.11-0.39) points from 2010 to 2015. Moreover, our results show that the increase was most pronounced in primary care, whereas in hospitals SRIS did not increase between 2010 and 2015. SRIS increased more among those in a leadership position. On-call duties and high time-pressures were associated with higher SRIS levels during all waves. Changing, difficult, and poorly functioning information systems (IS) are a prominent source of stress among Finnish physicians and this perceived stress continues to increase. Organizations should implement arrangements to ease stress stemming from IS especially for those with a high workload and on-call or leadership duties. To decrease IS-related stress, it would be important to study in more detail the main IS factors that contribute to SRIS. Earlier studies indicate that the usability and stability

Process variables in organizational stress management intervention evaluation research: a systematic review.

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Havermans, Bo M; Schlevis, Roosmarijn Mc; Boot, Cécile Rl; Brouwers, Evelien Pm; Anema, Johannes; van der Beek, Allard J

2016-09-01

This systematic review aimed to explore which process variables are used in stress management intervention (SMI) evaluation research. A systematic review was conducted using seven electronic databases. Studies were included if they reported on an SMI aimed at primary or secondary stress prevention, were directed at paid employees, and reported process data. Two independent researchers checked all records and selected the articles for inclusion. Nielsen and Randall's model for process evaluation was used to cluster the process variables. The three main clusters were context, intervention, and mental models. In the 44 articles included, 47 process variables were found, clustered into three main categories: context (two variables), intervention (31 variables), and mental models (14 variables). Half of the articles contained no reference to process evaluation literature. The collection of process evaluation data mostly took place after the intervention and at the level of the employee. The findings suggest that there is great heterogeneity in methods and process variables used in process evaluations of SMI. This, together with the lack of use of a standardized framework for evaluation, hinders the advancement of process evaluation theory development.

Prior stress exposure increases pain behaviors in a rat model of full thickness thermal injury.

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Nyland, Jennifer E; McLean, Samuel A; Averitt, Dayna L

2015-12-01

Thermal burns among individuals working in highly stressful environments, such as firefighters and military Service Members, are common. Evidence suggests that pre-injury stress may exaggerate pain following thermal injury; however current animal models of burn have not evaluated the potential influence of pre-burn stress. This sham-controlled study evaluated the influence of prior stress exposure on post-burn thermal and mechanical sensitivity in male Sprague-Dawley rats. Rats were exposed to 20 min of inescapable swim stress or sham stress once per day for three days. Exposure to inescapable swim stress (1) increased the intensity and duration of thermal hyperalgesia after subsequent burn and (2) accelerated the onset of thermal hyperalgesia and mechanical allodynia after subsequent burn. This stress-induced exacerbation of pain sensitivity was reversed by pretreatment and concurrent treatment with the serotonin-norepinephrine reuptake inhibitor (SNRI) duloxetine. These data suggest a better understanding of mechanisms by which prior stress augments pain after thermal burn may lead to improved pain treatments for burn survivors. Copyright © 2015 Elsevier Ltd and ISBI. All rights reserved.

Moderate altitude but not additional endurance training increases markers of oxidative stress in exhaled breath condensate.

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Heinicke, Ilmar; Boehler, Annette; Rechsteiner, Thomas; Bogdanova, Anna; Jelkmann, Wolfgang; Hofer, Markus; Rawlings, Pablo; Araneda, Oscar F; Behn, Claus; Gassmann, Max; Heinicke, Katja

2009-07-01

Oxidative stress occurs at altitude, and physical exertion might enhance this stress. In the present study, we investigated the combined effects of exercise and moderate altitude on redox balance in ten endurance exercising biathletes, and five sedentary volunteers during a 6-week-stay at 2,800 m. As a marker for oxidative stress, hydrogen peroxide (H(2)O(2)) was analyzed by the biosensor measuring system Ecocheck, and 8-iso prostaglandin F2alpha (8-iso PGF2alpha) was determined by enzyme immunoassay in exhaled breath condensate (EBC). To determine the whole blood antioxidative capacity, we measured reduced glutathione (GSH) enzymatically using Ellman's reagent. Exercising athletes and sedentary volunteers showed increased levels of oxidative markers at moderate altitude, contrary to our expectations; there was no difference between both groups. Therefore, all subjects' data were pooled to examine the oxidative stress response exclusively due to altitude exposure. H(2)O(2) levels increased at altitude and remained elevated for 3 days after returning to sea level (p altitude, but declined immediately after returning to sea level (p altitude resulted in elevated GSH levels (p altitude (p altitude for up to 6 weeks increases markers of oxidative stress in EBC independent of additional endurance training. Notably, this oxidative stress is still detectable 3 days upon return to sea level.

Molecular Mechanisms of Stress-Induced Increases in Fear Memory Consolidation within the Amygdala

OpenAIRE

Aubry, Antonio V.; Serrano, Peter A.; Burghardt, Nesha S.

2016-01-01

Stress can significantly impact brain function and increase the risk for developing various psychiatric disorders. Many of the brain regions that are implicated in psychiatric disorders and are vulnerable to the effects of stress are also involved in mediating emotional learning. Emotional learning has been a subject of intense investigation for the past 30 years, with the vast majority of studies focusing on the amygdala and its role in associative fear learning. However, the mechanisms by w...

Molecular Mechanisms of Stress-Induced Increases in Fear Memory Consolidation Within the Amygdala

OpenAIRE

Antonio Aubry; Antonio Aubry; Peter Serrano; Peter Serrano; Nesha Burghardt; Nesha Burghardt

2016-01-01

Stress can significantly impact brain function and increase the risk for developing various psychiatric disorders. Many of the brain regions that are implicated in psychiatric disorders and are vulnerable to the effects of stress are also involved in mediating emotional learning. Emotional learning has been a subject of intense investigation for the past 30 years, with the vast majority of studies focusing on the amygdala and its role in associative fear learning. However, the mechanisms by...

Brief strategic therapy in first myocardial infarction patients with increased levels of stress: a randomized clinical trial.

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Rakowska, Jadwiga Małgorzata

2015-01-01

Little is known about the impact of interventions targeting chronic stress levels on clinical outcomes among myocardial infarction (MI) patients with increased levels of stress. To examine the impact of the addition of brief strategic therapy (BST) to usual care (UC) on clinical outcomes in first MI patients with increased levels of stress. Eighty-one patients were randomly assigned to BST in conjunction with UC (medical treatment, risk factor information, and guidance on unhealthy behavior change) or to UC. The outcome measures were scores on the Perceived Stress Scale, reinfarction and cardiac mortality rates, and scores on the Health Survey. Measures were taken before, post-treatment, and at two follow-ups. Patients subjected to BST showed reduced perceived stress at post-treatment and maintained decreased levels at follow-ups. At 1-year follow-up, they had a lower rate of non-fatal reinfarction, and at 2.5-year follow-up, they had a lower rate of fatal reinfarction. Their mental and physical health was improved at post-treatment and this was sustained at follow-ups. The addition of BST to UC favorably influences the disease course after MI in patients with increased levels of stress.

Recovery of Work-Related Stress: Complaint Reduction and Work-Resumption are Relatively Independent Processes.

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de Vente, Wieke; Kamphuis, Jan Henk; Blonk, Roland W B; Emmelkamp, Paul M G

2015-09-01

The process of recovery from work-related stress, consisting of complaint reduction and work-resumption, is not yet fully understood. The aim of this study was to investigate predictors of complaint reduction and work-resumption, as well as testing complaint reduction as a mediator in the association between predictors and work-resumption. Seventy-one patients on sickness-leave because of work-related stress complaints were followed over a period of 13 months. Predictors comprised personal (demographics, coping, cognitions), work-related (job-characteristics, social support), and illness-related (complaint duration, absence duration) variables. Dependent variables were distress complaints, burnout complaints, and work-resumption. Complaints reduced considerably over time to borderline clinical levels and work-resumption increased to 68% at 13 months. Predictors of stronger reduction of distress complaints were male gender, less working hours, less decision authority, more co-worker support, and shorter absence duration. Predictors of stronger reduction of burnout complaints were male gender, lower age, high education, less avoidant coping, less decision authority, more job security, and more co-worker support. Predictors of work-resumption were lower age and stronger reduction of burnout complaints. No indication for a mediating role of burnout complaints between the predictor age and work-resumption was found. Complaint reduction and work-resumption are relatively independent processes. Symptom reduction is influenced by individual and work-related characteristics, which holds promise for a multidisciplinary treatment approach for work-related stress.

Mechanisms of stress-induced cellular HSP72 release: implications for exercise-induced increases in extracellular HSP72.

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Lancaster, Graeme I; Febbraio, Mark A

2005-01-01

The heat shock proteins are a family of highly conserved proteins with critical roles in maintaining cellular homeostasis and in protecting the cell from stressful conditions. While the critical intracellular roles of heat shock proteins are undisputed, evidence suggests that the cell possess the necessary machinery to actively secrete specific heat shock proteins in response to cellular stress. In this review, we firstly discuss the evidence that physical exercise induces the release of heat shock protein 72 from specific tissues in humans. Importantly, it appears as though this release is the result of an active secretory process, as opposed to non-specific processes such as cell lysis. Next we discuss recent in vitro evidence that has identified a mechanistic basis for the observation that cellular stress induces the release of a specific subset of heat shock proteins. Importantly, while the classical protein secretory pathway does not seem to be involved in the stress-induced release of HSP72, we discuss the evidence that lipid-rafts and exosomes are important mediators of the stress-induced release of HSP72.

[The effect of work-related stress on the occurrence of increased blood pressure].

Science.gov (United States)

Budaj, A; Cybulski, J; Kułakowski, P; Makowska, E; Rezler, J; Lange, J; Gorzkowska, J; Abramowski, S

In 546 officials the arterial blood pressure was measured twice at the beginning and at the end of a working day, filling also an inquiry form. As hypertension systolic BP over 160 mm Hg (21.3 kPa) or more, and diastolic BP 96 mm Hg (12.7 kPa) or more were accepted. In 90 subjects (16.5%) above normal pressure values were found. Hypertension had been diagnosed previously in 50 subjects in this group (55.5%) but only 13 of them (26%) were treated systematically. Excessive stress of work was complained of by 62.6% of the subjects. Increased blood pressure was found significantly more frequently in the group perceiving excessive stress of work (19.9%) as compared to those not experiencing this stress (10.8%, p less than 0.1). In the group in managerial posts these proportions were 24.8% and 14.4% respectively (p less than 0.1). Blood pressure rise to abnormal levels during the working day occurred also significantly more frequently in the group experiencing it this was noted only in 1.6% of cases (p less than 0.5). The knowledge of own hypertension was very low in this group. These results indicate the necessity of increasing prophylactic measures in the form of greater frequency of control measurements of the blood pressure, better health education, and limitation of stress situations in working environment.

Increased oxidative stress mediates the antitumor effect of PARP inhibition in ovarian cancer

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Dong Hou

2018-07-01

Full Text Available PARP inhibitors have been widely tested in clinical trials, especially for the treatment of breast cancer and ovarian cancer, and were shown to be highly successful. Because PARP primarily functions in sensing and repairing DNA strand breaks, the therapeutic effect of PARP inhibition is generally believed to be attributed to impaired DNA repair. We here report that oxidative stress is also increased by PARP inhibition and mediates the antitumor effect. We showed that PARP1 is highly expressed in specimens of high grade serous ovarian carcinoma and its activity is required for unperturbed proliferation of ovarian cancer cells. Inhibition or depletion of PARP leads to not only an increase in DNA damage, but also an elevation in the levels of reactive oxygen species (ROS. Importantly, antioxidant N-acetylcysteine (NAC significantly attenuated the induction of DNA damage and the perturbation of proliferation by PARP inhibition or depletion. We further showed that NADPH oxidases 1 and 4 were significantly upregulated by PARP inhibition and were partially responsible for the induction of oxidative stress. Depletion of NOX1 and NOX4 partially rescued the growth inhibition of PARP1-deficient tumor xenografts. Our findings suggest that in addition to compromising the repair of DNA damage, PARP inhibition or depletion may exert extra antitumor effect by elevating oxidative stress in ovarian cancer cells. Keywords: PARP1, Oxidative stress, NADPH oxidases, Ovarian cancer

Cilnidipine lowered psychological stress-induced increase in blood pressure in a hypertensive man: a case report

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Tsuji Sadatoshi

2007-09-01

Full Text Available Abstract Background In some hypertensive patients, psychological stress makes blood pressure difficult to control and causes physical symptoms such as headache or dizziness. We report the case of a hypertensive man whose psychological stress-induced increase in blood pressure was attenuated by cilnidipine. Case Presentation The patient (a 72-year-old man had hypertension and was on antihypertensive therapy. When mentally concentrating, he experienced occipital headaches and dizziness, and despite thorough testing, no abnormality was found. He was subsequently referred to our department. The mirror drawing test (MDT, a psychological stress test, increased blood pressure by about 40 mmHg, and the patient described occipital headache. Plasma noradrenaline level also increased from 212 to 548 pg/ml. We therefore switched the patient from nifedipine, an L-type calcium (Ca channel blocker, to cilnidipine, an L-type/N-type Ca channel blocker with suppressive effects on sympathetic activity. Cilnipidine attenuated MDT-induced an increase in blood pressure and plasma noradrenaline level and prevented the development of headache during testing. Conclusion These findings suggest that cilnidipine is a useful antihypertensive agent for hypertensive patients in whom psychological stress causes marked fluctuations in blood pressure.

STRESS AND NEURODEVELOPMENTAL PROCESSES IN THE EMERGENCE OF PSYCHOSIS

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Holtzman, C. W.; Trotman, H. D.; Goulding, S. M.; Ryan, A. T.; Macdonald, A. N.; Shapiro, D. I.; Brasfield, J. L.; Walker, E. F.

2014-01-01

The notion that stress plays a role in the etiology of psychotic disorders, especially schizophrenia, is longstanding. However, it is only in recent years that the potential neural mechanisms mediating this effect have come into sharper focus. The introduction of more sophisticated models of the interplay between psychosocial factors and brain function has expanded our opportunities for conceptualizing more detailed psychobiological models of stress in psychosis. Further, scientific advances in our understanding of adolescent brain development have shed light on a pivotal question that has challenged researchers; namely, why the first episode of psychosis typically occurs in late adolescence/young adulthood. In this paper, we begin by reviewing the evidence supporting associations between psychosocial stress and psychosis in diagnosed patients as well as individuals at clinical high risk for psychosis. We then discuss biological stress systems and examine changes that precede and follow psychosis onset. Next, research findings on structural and functional brain characteristics associated with psychosis are presented; these findings suggest that normal adolescent neuromaturational processes may go awry, thereby setting the stage for the emergence of psychotic syndromes. Finally, a model of neural mechanisms underlying the pathogenesis of psychosis is presented and directions for future research strategies are explored. PMID:23298853

Increased prevalence of posttraumatic stress disorder in CRPS.

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Speck, V; Schlereth, T; Birklein, F; Maihöfner, C

2017-03-01

Although specific psychological disorders in complex regional pain syndrome (CRPS) have not been identified, studies suggest that CRPS patients may have increased rates of traumatic life events. Because these events do not always lead to apparent psychological symptoms, we systematically screened CRPS patients for posttraumatic stress disorder (PTSD) to determine if PTSD could be a risk factor for CRPS. Consecutive CRPS patients referred to two university hospital centres (University of Erlangen, UMC Mainz) between December 2011 and April 2013 were prospectively examined using a diagnostic PTSD instrument (Post-traumatic Stress Diagnostic Scale (PDS). We also tested maladaptive coping strategies (brief-COPE inventory) and the PDS severity score as predictors for CRPS. Patients with non-CRPS extremity pain and healthy individuals were used as control groups. We collected data from 152 patients with CRPS, 55 control patients and 55 age- and sex-matched healthy individuals. Fifty-eight CRPS patients (38%), six non-CRPS pain patients (10%) and two healthy individuals (4%) met diagnostic criteria for PTSD. Initial PTSD symptom onset was prior to CRPS in 50 CRPS patients (86%) and during the course of CRPS in eight patients. Results of a logistic regression revealed that the PTSD severity score was associated with CRPS (p CRPS than it is in the general population. Research has not yet provided support for specific psychological predictors for CRPS. © 2016 European Pain Federation - EFIC®.

Pre-cold stress increases acid stress resistance and induces amino ...

African Journals Online (AJOL)

pre-adapted to cold stress revealed induction of amino acid homeostasis and energy ... substrate, thereby reducing yeast and mould ..... spontaneous mutation of llmg_1816 (gdpp) induced by .... species to UV-B-induced damage in bacteria. J.

Climatic stress increases forest fire severity across the western United States

Science.gov (United States)

Phillip J. van Mantgem; Jonathan C.B. Nesmith; MaryBeth Keifer; Eric E. Knapp; Alan Flint; Lorriane Flint

2013-01-01

Pervasive warming can lead to chronic stress on forest trees, which may contribute to mortality resulting from fire-caused injuries. Longitudinal analyses of forest plots from across the western US show that high pre-fire climatic water deficit was related to increased post-fire tree mortality probabilities. This relationship between climate and fire was present after...

Hardiness and the response to stressful situations: Investigating mediating processes

NARCIS (Netherlands)

Delahaij, R.; Gaillard, A.W.K.; Dam, K. van

2010-01-01

The present study investigated mediating processes that explain how hardiness influences the way people respond to a stressful situation. Coping style and coping self-efficacy were investigated as mediating variables. Using a longitudinal design, hardiness, coping style and coping self-efficacy, and

Chewing ameliorates stress-induced suppression of spatial memory by increasing glucocorticoid receptor expression in the hippocampus.

Science.gov (United States)

Miyake, Shinjiro; Yoshikawa, Gota; Yamada, Kentaro; Sasaguri, Ken-Ichi; Yamamoto, Toshiharu; Onozuka, Minoru; Sato, Sadao

2012-03-29

Chewing alters hypothalamic-pituitary-adrenal axis function and improves the ability to cope with stress in rodents. Given that stress negatively influences hippocampus-dependent learning and memory, we aimed to elucidate whether masticatory movements, namely chewing, improve the stress-induced impairment of spatial memory in conjunction with increased hippocampal glucocorticoid receptor expression. Male Sprague-Dawley rats were subjected to restraint stress by immobilization for 2h: the stress with chewing (SC) group were allowed to chew on a wooden stick during the latter half of the immobilization period, whereas the stress without chewing (ST) group were not allowed to do so. Performance in the Morris water maze test was significantly impaired in the ST group compared with the SC group. Further, the numbers of glucocorticoid receptor immunopositive neurons in the hippocampal cornu ammonis 1 region were significantly lower in the ST group than in the control and SC groups. The control and SC rats showed no significant differences in both the water maze performance and the numbers of glucocorticoid receptor-immunopositive neurons. The immunohistochemical finding correlated with the performance in the water maze test. These results suggest that chewing is a behavioral mechanism to cope with stress by increasing hippocampal glucocorticoid receptor expression. Copyright © 2012 Elsevier B.V. All rights reserved.

[Perception, processing of visual information and resistance to emotional stresses in athletes of different ages].

Science.gov (United States)

Korobeĭnikova, L H; Makarchuk, M Iu

2013-01-01

Among the numerous studies devoted to the study of perception and information processing, no data available on the effects of age on these processes. In this paper we studied the influence of psycho-emotional stress and different levels of stress on the mental processes of perception and information processing in highly skilled athletes divided into two groups. The first group included the athletes aged 19-24 years (12 athletes, members of the Ukrainian team in Greco-Roman wrestling), the second group included the athletes aged 27-31 years (7 highly skilled athletes, members of the Ukrainian team in Greco-Roman wrestling). We revealed that the athletes of the first group had higher productivity and better visual perception and visual information processing efficiency, compared with athletes from the second group. This observation suggests a dependency of cognitive component of perception and information processing on the age of the athletes. Sportsmen from the second group had higher stress resistance compared to the older age group.

Deficiency of heat shock transcription factor 1 suppresses heat stress-associated increase in slow soleus muscle mass of mice.

Science.gov (United States)

Ohno, Y; Egawa, T; Yokoyama, S; Nakai, A; Sugiura, T; Ohira, Y; Yoshioka, T; Goto, K

2015-12-01

Effects of heat shock transcription factor 1 (HSF1) deficiency on heat stress-associated increase in slow soleus muscle mass of mice were investigated. Both HSF1-null and wild-type mice were randomly assigned to control and heat-stressed groups. Mice in heat-stressed group were exposed to heat stress (41 °C for 60 min) in an incubator without anaesthesia. Significant increase in wet and dry weights, and protein content of soleus muscle in wild-type mice was observed seven days after the application of the heat stress. However, heat stress had no impact on soleus muscle mass in HSF1-null mice. Neither type of mice exhibited much effect of heat stress on HSF mRNA expression (HSF1, HSF2 and HSF4). On the other hand, heat stress upregulated heat shock proteins (HSPs) at the mRNA (HSP72) and protein (HSP72 and HSP110) levels in wild-type mice, but not in HSF1-null mice. The population of Pax7-positive nuclei relative to total myonuclei of soleus muscle in wild-type mice was significantly increased by heat stress, but not in HSF1-null mice. Furthermore, the absence of HSF1 gene suppressed heat stress-associated phosphorylation of Akt and p70 S6 kinase (p-p70S6K) in soleus muscle. Heat stress-associated increase in skeletal muscle mass may be induced by HSF1 and/or HSF1-mediated stress response that activates muscle satellite cells and Akt/p70S6K signalling pathway. © 2015 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

Exercise-mediated wall shear stress increases mitochondrial biogenesis in vascular endothelium.

Directory of Open Access Journals (Sweden)

Boa Kim

Full Text Available Enhancing structural and functional integrity of mitochondria is an emerging therapeutic option against endothelial dysfunction. In this study, we sought to investigate the effect of fluid shear stress on mitochondrial biogenesis and mitochondrial respiratory function in endothelial cells (ECs using in vitro and in vivo complementary studies.Human aortic- or umbilical vein-derived ECs were exposed to laminar shear stress (20 dyne/cm2 for various durations using a cone-and-plate shear apparatus. We observed significant increases in the expression of key genes related to mitochondrial biogenesis and mitochondrial quality control as well as mtDNA content and mitochondrial mass under the shear stress conditions. Mitochondrial respiratory function was enhanced when cells were intermittently exposed to laminar shear stress for 72 hrs. Also, shear-exposed cells showed diminished glycolysis and decreased mitochondrial membrane potential (ΔΨm. Likewise, in in vivo experiments, mice that were subjected to a voluntary wheel running exercise for 5 weeks showed significantly higher mitochondrial content determined by en face staining in the conduit (greater and lesser curvature of the aortic arch and thoracic aorta and muscle feed (femoral artery arteries compared to the sedentary control mice. Interestingly, however, the mitochondrial biogenesis was not observed in the mesenteric artery. This region-specific adaptation is likely due to the differential blood flow redistribution during exercise in the different vessel beds.Taken together, our findings suggest that exercise enhances mitochondrial biogenesis in vascular endothelium through a shear stress-dependent mechanism. Our findings may suggest a novel mitochondrial pathway by which a chronic exercise may be beneficial for vascular function.

Systemic inflammatory changes and increased oxidative stress in rural Indian women cooking with biomass fuels

International Nuclear Information System (INIS)

Dutta, Anindita; Ray, Manas Ranjan; Banerjee, Anirban

2012-01-01

The study was undertaken to investigate whether regular cooking with biomass aggravates systemic inflammation and oxidative stress that might result in increase in the risk of developing cardiovascular disease (CVD) in rural Indian women compared to cooking with a cleaner fuel like liquefied petroleum gas (LPG). A total of 635 women (median age 36 years) who cooked with biomass and 452 age-matched control women who cooked with LPG were enrolled. Serum interleukin-6 (IL-6), C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α) and interleukin-8 (IL-8) were measured by ELISA. Generation of reactive oxygen species (ROS) by leukocytes was measured by flow cytometry, and erythrocytic superoxide dismutase (SOD) was measured by spectrophotometry. Hypertension was diagnosed following the Seventh Report of the Joint Committee. Tachycardia was determined as pulse rate > 100 beats per minute. Particulate matter of diameter less than 10 and 2.5 μm (PM 10 and PM 2.5 , respectively) in cooking areas was measured using real-time aerosol monitor. Compared with control, biomass users had more particulate pollution in indoor air, their serum contained significantly elevated levels of IL-6, IL-8, TNF-α and CRP, and ROS generation was increased by 37% while SOD was depleted by 41.5%, greater prevalence of hypertension and tachycardia compared to their LPG-using neighbors. PM 10 and PM 2.5 levels were positively associated with markers of inflammation, oxidative stress and hypertension. Inflammatory markers correlated with raised blood pressure. Cooking with biomass exacerbates systemic inflammation, oxidative stress, hypertension and tachycardia in poor women cooking with biomass fuel and hence, predisposes them to increased risk of CVD development compared to the controls. Systemic inflammation and oxidative stress may be the mechanistic factors involved in the development of CVD. -- Highlights: ► Effect of chronic biomass smoke exposure on cardiovascular health was

Effects of face/head and whole body cooling during passive heat stress on human somatosensory processing.

Science.gov (United States)

Nakata, Hiroki; Namba, Mari; Kakigi, Ryusuke; Shibasaki, Manabu

2017-06-01

We herein investigated the effects of face/head and whole body cooling during passive heat stress on human somatosensory processing recorded by somatosensory-evoked potentials (SEPs) at C4' and Fz electrodes. Fourteen healthy subjects received a median nerve stimulation at the left wrist. SEPs were recorded at normothermic baseline (Rest), when esophageal temperature had increased by ~1.2°C (heat stress: HS) during passive heating, face/head cooling during passive heating (face/head cooling: FHC), and after HS (whole body cooling: WBC). The latencies and amplitudes of P14, N20, P25, N35, P45, and N60 at C4' and P14, N18, P22, and N30 at Fz were evaluated. Latency indicated speed of the subcortical and cortical somatosensory processing, while amplitude reflected the strength of neural activity. Blood flow in the internal and common carotid arteries (ICA and CCA, respectively) and psychological comfort were recorded in each session. Increases in esophageal temperature due to HS significantly decreased the amplitude of N60, psychological comfort, and ICA blood flow in the HS session, and also shortened the latencies of SEPs (all, P body temperature. Copyright © 2017 the American Physiological Society.

Ageing increases the sensitivity of neem (Azadirachta indica) seeds to imbibitional stress

NARCIS (Netherlands)

Neya, O.; Golovina, E.A.; Nijsse, J.; Hoekstra, F.A.

2004-01-01

Imbibitional stress was imposed on neem (Azadirachta indica) seeds by letting them soak for 1 h in water at unfavourable, low temperatures before further incubation at 30degreesC. Sensitivity to low imbibition temperatures increased with a decrease in seed moisture content (MC). To investigate a

Stress Modulates Reinforcement Learning in Younger and Older Adults

OpenAIRE

Lighthall, Nichole R.; Gorlick, Marissa A.; Schoeke, Andrej; Frank, Michael J.; Mather, Mara

2012-01-01

Animal research and human neuroimaging studies indicate that stress increases dopamine levels in brain regions involved in reward processing and stress also appears to increase the attractiveness of addictive drugs. The current study tested the hypothesis that stress increases reward salience, leading to more effective learning about positive than negative outcomes in a probabilistic selection task. Changes to dopamine pathways with age raise the question of whether stress effects on incentiv...

Altered Olfactory Processing of Stress Related Body Odors and Artificial Odors in Patients with Panic Disorder

OpenAIRE

Wintermann, Gloria-Beatrice; Donix, Markus; Joraschky, Peter; Gerber, Johannes; Petrowski, Katja

2014-01-01

Background: Patients with Panic Disorder (PD) direct their attention towards potential threat, followed by panic attacks, and increased sweat production. Onés own anxiety sweat odor influences the attentional focus, and discrimination of threat or non-threat. Since olfactory projection areas overlap with neuronal areas of a panic-specific fear network, the present study investigated the neuronal processing of odors in general and of stress-related sweat odors in particular in patients with PD...

Aberrant Neural Connectivity during Emotional Processing Associated with Posttraumatic Stress.

Science.gov (United States)

Sadeh, Naomi; Spielberg, Jeffrey M; Warren, Stacie L; Miller, Gregory A; Heller, Wendy

2014-11-01

Given the complexity of the brain, characterizing relations among distributed brain regions is likely essential to describing the neural instantiation of posttraumatic stress symptoms. This study examined patterns of functional connectivity among key brain regions implicated in the pathophysiology of posttraumatic stress disorder (PTSD) in 35 trauma-exposed adults using an emotion-word Stroop task. PTSD symptom severity (particularly hyperarousal symptoms) moderated amygdala-mPFC coupling during the processing of unpleasant words, and this moderation correlated positively with reported real-world impairment and amygdala reactivity. Reexperiencing severity moderated hippocampus-insula coupling during pleasant and unpleasant words. Results provide evidence that PTSD symptoms differentially moderate functional coupling during emotional interference and underscore the importance of examining network connectivity in research on PTSD. They suggest that hyperarousal is associated with negative mPFC-amygdala coupling and that reexperiencing is associated with altered insula-hippocampus function, patterns of connectivity that may represent separable indicators of dysfunctional inhibitory control during affective processing.

The impact of training process on the stress tests results of women cross country skiing representation.

OpenAIRE

Fusková, Dana

2015-01-01

Title: The impact of training process on the stress tests results of women cross country skiing representation. Aim: The aim of this thesis is the comparison of the results of stress tests carried out preparatory period before and after the preparation period and whether the results were influenced by the applied training process. Methods: In this thesis was used background research of professional publications, content analyzes of documents and comparison of the results of stress tests and c...

Study on residual stress across the pipes' thickness using outer surface rapid heating. Development of pipe outer surface irradiated laser stress improvement process (L-SIP)

International Nuclear Information System (INIS)

Ohta, Takahiro; Terasaki, Toshio

2009-01-01

The new process called L-SIP (outer surface irradiated Laser Stress Improvement Process) is developed to improve the tensile residual stress of the inner surface near the butt welded joints of pipes in the compression stress. The temperature gradient occurs in the thickness of pipes in heating the outer surface rapidly by laser beam. By the thermal expansion difference between the inner surface and the outer surface, the compression plastic strain generates near the outer surface and the tensile plastic strain generates near the inner surface of pipes. The compression stress occurs near the inner surface of pipes by the plastic deformation. In this paper, the theoretical equation which calculates residual stress distribution from the inherent strain distribution in the thickness of pipes is derived. And, the relation between the distribution of temperature and the residual stress in the thickness is examined for various pipes size. (1) By rapidly heating from the outer surface, the residual stress near the inner surface of the pipe is improved to the compression stress. (2) Pipes size hardly affects the distribution of the residual stress in the stainless steel pipes for piping (JISG3459). (3) The temperature rising area from the outside is smaller, the area of the compression residual stress near the inner surface becomes wider. (author)

A Benzimidazole Proton Pump Inhibitor Increases Growth and Tolerance to Salt Stress in Tomato

Directory of Open Access Journals (Sweden)

Michael J. Van Oosten

2017-07-01

Full Text Available Pre-treatment of tomato plants with micromolar concentrations of omeprazole (OP, a benzimidazole proton pump inhibitor in mammalian systems, improves plant growth in terms of fresh weight of shoot and roots by 49 and 55% and dry weight by 54 and 105% under salt stress conditions (200 mM NaCl, respectively. Assessment of gas exchange, ion distribution, and gene expression profile in different organs strongly indicates that OP interferes with key components of the stress adaptation machinery, including hormonal control of root development (improving length and branching, protection of the photosynthetic system (improving quantum yield of photosystem II and regulation of ion homeostasis (improving the K+:Na+ ratio in leaves and roots. To our knowledge OP is one of the few known molecules that at micromolar concentrations manifests a dual function as growth enhancer and salt stress protectant. Therefore, OP can be used as new inducer of stress tolerance to better understand molecular and physiological stress adaptation paths in plants and to design new products to improve crop performance under suboptimal growth conditions.Highlight: Omeprazole enhances growth of tomato and increases tolerance to salinity stress through alterations of gene expression and ion uptake and transport.

Stress strain modelling of casting processes in the framework of the control volume method

DEFF Research Database (Denmark)

Hattel, Jesper; Andersen, Søren; Thorborg, Jesper

1998-01-01

Realistic computer simulations of casting processes call for the solution of both thermal, fluid-flow and stress/strain related problems. The multitude of the influencing parameters, and their non-linear, transient and temperature dependent nature, make the calculations complex. Therefore the nee......, the present model is based on the mainly decoupled representation of the thermal, mechanical and microstructural processes. Examples of industrial applications, such as predicting residual deformations in castings and stress levels in die casting dies, are presented...... for fast, flexible, multidimensional numerical methods is obvious. The basis of the deformation and stress/strain calculation is a transient heat transfer analysis including solidification. This paper presents an approach where the stress/strain and the heat transfer analysis uses the same computational...... domain, which is highly convenient. The basis of the method is the control volume finite difference approach on structured meshes. The basic assumptions of the method are shortly reviewed and discussed. As for other methods which aim at application oriented analysis of casting deformations and stresses...

Financial strain is associated with increased oxidative stress levels: the Women's Health and Aging Studies.

Science.gov (United States)

Palta, Priya; Szanton, Sarah L; Semba, Richard D; Thorpe, Roland J; Varadhan, Ravi; Fried, Linda P

2015-01-01

Elevated oxidative stress levels may be one mechanism contributing to poor health outcomes. Financial strain and oxidative stress are each predictors of morbidity and mortality, but little research has investigated their relationship. Community-dwelling older adults (n = 728) from the Women's Health and Aging Studies I and II were included in this cross-sectional analysis. Financial strain was ascertained as an ordinal response to: "At the end of the month, do you have more than enough money left over, just enough, or not enough?" Oxidative stress was measured using serum protein carbonyl concentrations. Linear regression was used to quantify the relationship between financial strain and oxidative stress. Participants who reported high financial strain exhibited 13.4% higher protein carbonyl concentrations compared to individuals who reported low financial strain (p = 0.002). High financial strain may be associated with increased oxidative stress, suggesting that oxidative stress could mediate associations between financial strain and poor health. Copyright © 2015 Elsevier Inc. All rights reserved.

Modelling Of Residual Stresses Induced By High Speed Milling Process

International Nuclear Information System (INIS)

Desmaison, Olivier; Mocellin, Katia; Jardin, Nicolas

2011-01-01

Maintenance processes used in heavy industries often include high speed milling operations. The reliability of the post-process material state has to be studied. Numerical simulation appears to be a very interesting way to supply an efficient residual stresses (RS) distribution prediction.Because the adiabatic shear band and the serrated chip shaping are features of the austenitic stainless steel high speed machining, a 2D high speed orthogonal cutting model is briefly presented. This finite element model, developed on Forge registered software, is based on data taken from Outeiro and al.'s paper [1]. A new behaviour law fully coupling Johnson-Cook's constitutive law and Latham and Cockcroft's damage model is detailed in this paper. It ensures results that fit those found in literature.Then, the numerical tools used on the 2D model are integrated to a 3D high speed milling model. Residual stresses distribution is analysed, on the surface and into the depth of the material. Various revolutions and passes of the two teeth hemispheric mill on the workpiece are simulated. Thus the sensitivity of the residual stresses generation to the cutting conditions can be discussed. In order to validate the 3D model, a comparison of the cutting forces measured by EDF R and D to those given by numerical simulations is achieved.

Increased anxiety, voluntary alcohol consumption and ethanol-induced place preference in mice following chronic psychosocial stress.

Science.gov (United States)

Bahi, Amine

2013-07-01

Stress exposure is known to be a risk factor for alcohol use and anxiety disorders. Comorbid chronic stress and alcohol dependence may lead to a complicated and potentially severe treatment profile. To gain an understanding of the interaction between chronic psychosocial stress and drug exposure, we studied the effects of concomitant chronic stress exposure on alcohol reward using two-bottle choice and ethanol-conditioned place preference (CPP). The study consisted of exposure of the chronic subordinate colony (CSC) mice "intruders" to an aggressive "resident" mouse for 19 consecutive days. Control mice were single housed (SHC). Ethanol consumption using two-bottle choice paradigm and ethanol CPP acquisition was assessed at the end of this time period. As expected, CSC exposure increased anxiety-like behavior and reduced weight gain as compared to SHC controls. Importantly, in the two-bottle choice procedure, CSC mice showed higher alcohol intake than SHC. When testing their response to ethanol-induced CPP, CSC mice achieved higher preference for the ethanol-paired chamber. In fact, CSC exposure increased ethanol-CPP acquisition. Taken together, these data demonstrate the long-term consequences of chronic psychosocial stress on alcohol intake in male mice, suggesting chronic stress as a risk factor for developing alcohol consumption and/or anxiety disorders.

Reduction of tensile residual stresses during the drawing process of tungsten wires

International Nuclear Information System (INIS)

Rodriguez Ripoll, Manel; Weygand, Sabine M.; Riedel, Hermann

2010-01-01

Tungsten wires are commonly used in the lighting industry as filaments for lamps. During the drawing process, the inhomogeneous deformation imparted by the drawing die causes tensile residual stresses at the wire surface in circumferential direction. These stresses have a detrimental effect for the wire because they are responsible for driving longitudinal cracks, known as splits. This work proposes two methods for reducing the residual stresses during wire drawing, namely applying an advanced die geometry and performing an inexpensive post-drawing treatment based on targeted bending operations. These two methods are analyzed with finite element simulations using material parameters obtained by mechanical tests on tungsten wires at different temperatures as input data. The computed results predict a substantial reduction of the circumferential residual stresses, thus reducing the risk of splitting.

A New Test Device for Characterization of Mechanical Stress Caused by Packaging Processes

International Nuclear Information System (INIS)

Hirsch, Soeren; Doerner, Steffen; Hauptmann, Peter; Schmidt, Bertram

2006-01-01

This paper reports on a new method for estimation and minimization of mechanical stress on MEMS sensor and actuator structures due to packaging processes based on flip chip technology. For studying mechanical stress a test chip with silicon membranes was fabricated. A network of piezo-resistive solid state resistors created by diffusion was used to measure the surface tension pattern between adjacent membranes. Finite element method simulation was used to calculate the stress profile and to determine the optimum positions for placing the resistive network

Work-related stress and posttraumatic stress in emergency medical services.

Science.gov (United States)

Donnelly, Elizabeth

2012-01-01

Recent research efforts in emergency medical services (EMS) has identified variability in the ability of EMS personnel to recognize their level of stress-related impairment. Developing a better understanding of how workplace stress may affect EMS personnel is a key step in the process of increasing awareness of the impact of work-related stress and stress-related impairment. This paper demonstrates that for those in EMS, exposure to several types of workplace stressors is linked to stress reactions. Stress reactions such as posttraumatic stress symptomatology (PTSS) have the potential to negatively influence the health of EMS providers. This research demonstrates that two different types of work-related stress and alcohol use influence the development of PTSS. A probability sample of nationally registered emergency medical technician (EMT)-Basics and EMT-Paramedics (n = 1,633) completed an Internet-based survey. Respondents reported their levels of operational and organizational types of chronic stress, critical incident stress, alcohol use, and PTSS. Ordinary least squares regression illustrated that when demographic factors were controlled, organizational and operational forms of chronic stress, critical incident stress, and alcohol use were all significant predictors of PTSS (p stress and critical incident stress (p stress and alcohol use (p stress reaction. Higher levels of chronic stress, critical incident stress, and alcohol use significantly related to an increased level of PTSS. Further, for those reporting high levels of alcohol use or critical incident stress, interactions with high levels of chronic operational stress were associated with higher rates of PTSS. For those interested in the impact of work-related stress in EMS, these findings indicate that attention must be paid to levels of stress associated with both critical incident exposure as well as the chronic stress providers experience on a day-to-day basis.

Does perceived stress increase the risk of atrial fibrillation? A population-based cohort study in Denmark

DEFF Research Database (Denmark)

Graff, Simon; Prior, Anders; Fenger-Grøn, Morten

2017-01-01

Background Psychological stress is associated with increased risk of acute cardiovascular diseases, as myocardial infarction. We recently found a higher risk of atrial fibrillation following an acute stressful life event, but it remains unknown whether this also applies to common and less acute....... Conclusions This large population-based cohort study did not reveal a higher risk of atrial fibrillation among persons with a high degree of perceived stress after adjustment for participants' baseline characteristics....

Chemical and sensory quality of processed carrot puree as influenced by stress-induced phenolic compounds.

Science.gov (United States)

Talcott, S T; Howard, L R

1999-04-01

Physicochemical analysis of processed strained product was performed on 10 carrot genotypes grown in Texas (TX) and Georgia (GA). Carrots from GA experienced hail damage during growth, resulting in damage to their tops. Measurements included pH, moisture, soluble phenolics, total carotenoids, sugars, organic acids, and isocoumarin (6-MM). Sensory analysis was conducted using a trained panel to evaluate relationships between chemical and sensory attributes of the genotypes and in carrots spiked with increasing levels of 6-MM. Preharvest stress conditions in GA carrots seemed to elicit a phytoalexic response, producing compounds that impacted the perception of bitter and sour flavors. Spiking 6-MM into strained carrots demonstrated the role bitter compounds have in lowering sweetness scores while increasing the perception of sour flavor. Screening fresh carrots for the phytoalexin 6-MM has the potential to significantly improve the sensory quality of processed products.

Effect of processing conditions on residual stress distributions by bead-on-plate welding after surface machining

International Nuclear Information System (INIS)

Ihara, Ryohei; Mochizuki, Masahito

2014-01-01

Residual stress is important factor for stress corrosion cracking (SCC) that has been observed near the welded zone in nuclear power plants. Especially, surface residual stress is significant for SCC initiation. In the joining processes of pipes, butt welding is conducted after surface machining. Residual stress is generated by both processes, and residual stress distribution due to surface machining is varied by the subsequent butt welding. In previous paper, authors reported that residual stress distribution generated by bead on plate welding after surface machining has a local maximum residual stress near the weld metal. The local maximum residual stress shows approximately 900 MPa that exceeds the stress threshold for SCC initiation. Therefore, for the safety improvement of nuclear power plants, a study on the local maximum residual stress is important. In this study, the effect of surface machining and welding conditions on residual stress distribution generated by welding after surface machining was investigated. Surface machining using lathe machine and bead on plate welding with tungsten inert gas (TIG) arc under various conditions were conducted for plate specimens made of SUS316L. Then, residual stress distributions were measured by X-ray diffraction method (XRD). As a result, residual stress distributions have the local maximum residual stress near the weld metal in all specimens. The values of the local maximum residual stresses are almost the same. The location of the local maximum residual stress is varied by welding condition. It could be consider that the local maximum residual stress is generated by same generation mechanism as welding residual stress in surface machined layer that has high yield stress. (author)

Financial Stress, Parental Depressive Symptoms, Parenting Practices, and Children's Externalizing Problem Behaviors: Underlying Processes

Science.gov (United States)

Lee, Chih-Yuan Steven; Lee, Jaerim; August, Gerald J.

2011-01-01

This study examined the relationships among financial stress encountered by families, parents' social support, parental depressive symptoms, parenting practices, and children's externalizing problem behaviors to advance our understanding of the processes by which family financial stress is associated with children's problem behaviors. We also…

Study on the essential variables for pipe outer surface irradiated laser stress improvement process (L-SIP). Development of pipe outer surface irradiated laser stress improvement process (L-SIP)

International Nuclear Information System (INIS)

Ohta, Takahiro; Kamo, Kazuhiko; Muroya, Itaru; Asada, Seiji; Nakamura, Yasuo

2009-01-01

The new process called L-SIP (outer surface irradiated Laser Stress Improvement Process) is developed to improve the tensile residual stress of the inner surface near the butt welded joints of pipes in the compression stress. The temperature gradient occurs in the thickness of pipes in heating the outer surface rapidly by laser beam. By the thermal expansion difference between the inner surface and the outer surface, the compression stress occurs near the inner surface of pipes. In this paper, the essential variables for L-SIP is studied by experimental and FEM analysis. The range of the essential variables for L-SIP, which are defined by thermo-elastic FEM analysis, are Tmax=550 - 650degC, L Q /√rh ≥ 3, W Q /√rh ≥ 1.7, and, 0.04 ≤ F 0 ≤ 0.10 where Tmax is maximum temperature on the monitor point of the outer surface, F 0 is k x τ 0 /h 2 , k is thermal diffusivity coefficient, τ 0 is the temperature rise time from 100degC to maximum temperature on the monitor point of the outer surface, W Q is τ 0 x v, υ is moving velocity, L Q is the uniform temperature length in the axial direction, h is thickness of the pipe, and r is average radius of the pipe. It is showed by thermo-elastic-plastic FEM analysis that the residual stresses near the inner surface of pipes are improved in 4 different size pipes under the same essential variables. L-SIP is actually applied to welding joints of 4B x Sch160 and 2B x Sch80 SUS304 type stainless steel pipes within the defined range of the essential variables. The measured welding residual stresses on the inner surface near the welding joints are tensile. The residual stresses on the inner surface change to compression in all joints by L-SIP. (author)

Psychological stress alters the ultrastructure and increases IL-1β and TNF-α in mandibular condylar cartilage

International Nuclear Information System (INIS)

Lv, Xin; Li, Qiang; Wu, Shun; Sun, Jing; Zhang, Min; Chen, Yong-Jin

2012-01-01

Psychological factors can be correlated with temporomandibular disorders (TMDs), but the mechanisms are unknown. In the present study, we examined the microstructural changes and expression of proinflammatory cytokines in mandibular condylar cartilage of the temporomandibular joint (TMJ) in a psychological stress animal model. Male Sprague-Dawley rats (8 weeks old, 210 ± 10 g) were randomly divided into 3 groups: psychological stress (PS, N = 48), foot shock (FS, N = 24), and control (N = 48). After inducing psychological stress using a communication box with the FS rats for 1, 3, or 5 weeks, PS rats were sacrificed and compared to their matched control littermates, which received no stress and were killed at the same times as the PS rats. Body and adrenal gland weight were measured and corticosterone and adrenocorticotropic hormone levels were determined by radioimmunoassay. After hematoxylin-eosin staining for histological observation, the ultrastructure of the TMJ was examined by scanning electron microscopy. Transcription and protein levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were evaluated by ELISA and semi-quantitative RT-PCR. The PS group showed a significantly higher adrenal gland weight after 3 weeks of stress and higher hormone levels at weeks 1, 3, and 5. Histopathological changes and thinning cartilage were apparent at weeks 3 and 5. In the PS group, TNF-α increased at 1, 3, and 5 weeks and IL-1β increased significantly after 1 and 3 weeks of stress, and then decreased to normal levels by 5 weeks. Psychological stress increased plasma hormone levels and RT-PCR indicated increased IL-1β and TNF-α expression in the TMJ in a time-dependent manner. These results suggest that cytokine up-regulation was accompanied by stress-induced cartilage degeneration in the mandibular condyle. The proinflammatory cytokines play a potential role in initiating the cartilage destruction that eventually leads to the TMDs

Psychological stress alters the ultrastructure and increases IL-1β and TNF-α in mandibular condylar cartilage

Energy Technology Data Exchange (ETDEWEB)

Lv, Xin; Li, Qiang; Wu, Shun; Sun, Jing; Zhang, Min; Chen, Yong-Jin [Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, Xi' an, Shaanxi (China)

2012-06-22

Psychological factors can be correlated with temporomandibular disorders (TMDs), but the mechanisms are unknown. In the present study, we examined the microstructural changes and expression of proinflammatory cytokines in mandibular condylar cartilage of the temporomandibular joint (TMJ) in a psychological stress animal model. Male Sprague-Dawley rats (8 weeks old, 210 ± 10 g) were randomly divided into 3 groups: psychological stress (PS, N = 48), foot shock (FS, N = 24), and control (N = 48). After inducing psychological stress using a communication box with the FS rats for 1, 3, or 5 weeks, PS rats were sacrificed and compared to their matched control littermates, which received no stress and were killed at the same times as the PS rats. Body and adrenal gland weight were measured and corticosterone and adrenocorticotropic hormone levels were determined by radioimmunoassay. After hematoxylin-eosin staining for histological observation, the ultrastructure of the TMJ was examined by scanning electron microscopy. Transcription and protein levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were evaluated by ELISA and semi-quantitative RT-PCR. The PS group showed a significantly higher adrenal gland weight after 3 weeks of stress and higher hormone levels at weeks 1, 3, and 5. Histopathological changes and thinning cartilage were apparent at weeks 3 and 5. In the PS group, TNF-α increased at 1, 3, and 5 weeks and IL-1β increased significantly after 1 and 3 weeks of stress, and then decreased to normal levels by 5 weeks. Psychological stress increased plasma hormone levels and RT-PCR indicated increased IL-1β and TNF-α expression in the TMJ in a time-dependent manner. These results suggest that cytokine up-regulation was accompanied by stress-induced cartilage degeneration in the mandibular condyle. The proinflammatory cytokines play a potential role in initiating the cartilage destruction that eventually leads to the TMDs.

Psychological stress alters the ultrastructure and increases IL-1β and TNF-α in mandibular condylar cartilage

Directory of Open Access Journals (Sweden)

Xin Lv

2012-10-01

Full Text Available Psychological factors can be correlated with temporomandibular disorders (TMDs, but the mechanisms are unknown. In the present study, we examined the microstructural changes and expression of proinflammatory cytokines in mandibular condylar cartilage of the temporomandibular joint (TMJ in a psychological stress animal model. Male Sprague-Dawley rats (8 weeks old, 210 ± 10 g were randomly divided into 3 groups: psychological stress (PS, N = 48, foot shock (FS, N = 24, and control (N = 48. After inducing psychological stress using a communication box with the FS rats for 1, 3, or 5 weeks, PS rats were sacrificed and compared to their matched control littermates, which received no stress and were killed at the same times as the PS rats. Body and adrenal gland weight were measured and corticosterone and adrenocorticotropic hormone levels were determined by radioimmunoassay. After hematoxylin-eosin staining for histological observation, the ultrastructure of the TMJ was examined by scanning electron microscopy. Transcription and protein levels of interleukin-1β (IL-1β and tumor necrosis factor-α (TNF-α were evaluated by ELISA and semi-quantitative RT-PCR. The PS group showed a significantly higher adrenal gland weight after 3 weeks of stress and higher hormone levels at weeks 1, 3, and 5. Histopathological changes and thinning cartilage were apparent at weeks 3 and 5. In the PS group, TNF-α increased at 1, 3, and 5 weeks and IL-1β increased significantly after 1 and 3 weeks of stress, and then decreased to normal levels by 5 weeks. Psychological stress increased plasma hormone levels and RT-PCR indicated increased IL-1β and TNF-α expression in the TMJ in a time-dependent manner. These results suggest that cytokine up-regulation was accompanied by stress-induced cartilage degeneration in the mandibular condyle. The proinflammatory cytokines play a potential role in initiating the cartilage destruction that eventually leads to the TMDs.

The role of saliva in the process of oxidative stress – review of literature

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Anna Krysińska

2016-12-01

Full Text Available Background: Saliva constitutes a first line of defence against free radical-mediated oxidative stress, since the process of mastication and digestion promotes lipid peroxidation. During gingival inflammation, gingival crevicular fluid flow increases the change of saliva composition with products from the inflammatory response, modulating oxidative damages in the oral cavity. Authors review the current literature concerning the reactive oxygen species, oxidants, pro-oxidants and antioxidants in saliva, and methods for assessing the antioxidant capacity of saliva. Comparison of salivary antioxidant status in male and female subjects reveales a significant gender-related difference in saliva composition. The current data demonstrate a significant enhancement of the salivary antioxidant system in juvenile idiopathic arthritis patients. Also patients with chronic renal failure, diabetes and on hemodialysis show increase oxidative stress burden in both serum and saliva. The finding of reduced oral peroxidase levels in smoking subjects may represent a contributory mechanism for initiation and progression of cigarette smoke-related oral diseases such as oral cancer. The results of recent studies indicate that the total antioxidant capacity of saliva decreased in children with HIV infection. Conclusion: Whole saliva may contain simply measured indicators of oxidative processes. This may provide a tool for the development and monitoring of new treatment strategies. A non-invasive determination of the salivary concentrations of antioxidants such as superoxide dismutase (SOD and uric acid (UR allows the evaluation of the defensive capacity of the oral mucosa. Still, there is a need for standardization of methods for saliva sampling and testing protocol.

Stress/strain characteristics of Cu alloy sheath in situ processed MgB2 superconducting wires

International Nuclear Information System (INIS)

Katagiri, Kazumune; Kasaba, Koichi; Shoji, Yoshitaka

2005-01-01

The mechanical properties of copper and copper alloy (Cu-Zr, Cu-Be and Cu-Cr) sheath in situ PIT-processed MgB 2 superconducting wires were studied at room temperature (RT) and 4.2 K. The effects of stress-strain on the critical current (I c ) of the wires have also been studied at 4.2 K and in magnetic fields up to 5 T. It has been clarified that alloying the Cu sheath significantly increases the yield and flow stresses of the wires at both RT and 4.2 K. The 0.5% flow stresses of the Cu alloy sheath wire were 147-237 MPa, whereas that of Cu was 55 MPa. At RT, serration corresponding to multiple cracking was observed around a strain of 0.4% and the stress-strain curves saturated beyond that point. The strain dependence of I c prior to the critical strain (ε irr ) was different depending on the magnetic field; being almost constant at 2 T and increasing with strain at 5 T. The I c decreased beyond ε irr , which is much larger for Cu alloy sheath wires as compared to Cu sheath wire. This is due to the difference in the residual compressive strain in the MgB 2 core during cooling from the heat-treatment temperature to 4.2 K, which is determined through relaxation by yielding in the sheath materials. The transverse compression tests revealed that the I c of the Cu alloy sheath wire did not degrade up to 314 MPa, which is also higher than that of Cu sheath wire. (author)

Fluoxetine reverts chronic restraint stress-induced depression-like behaviour and increases neuropeptide Y and galanin expression in mice

DEFF Research Database (Denmark)

Christiansen, Søren Hofman Oliveira; Olesen, Mikkel Vestergaard; Wörtwein, Gitta

2011-01-01

Stressful life events and chronic stress are implicated in the development of depressive disorder in humans. Neuropeptide Y (NPY) and galanin have been shown to modulate the stress response, and exert antidepressant-like effects in rodents. To further investigate these neuropeptides in depression......-like behaviour, NPY and galanin gene expression was studied in brains of mice subjected to chronic restraint stress (CRS) and concomitant treatment with the antidepressant fluoxetine (FLX). CRS caused a significant increase in depression-like behaviour that was associated with increased NPY mRNA levels...... in the medial amygdala. Concomitant FLX treatment reverted depression-like effects of CRS and led to significant increases in levels of NPY and galanin mRNA in the dentate gyrus, amygdala, and piriform cortex. These findings suggest that effects on NPY and galanin gene expression could play a role...

Systemic inflammatory changes and increased oxidative stress in rural Indian women cooking with biomass fuels

Energy Technology Data Exchange (ETDEWEB)

Dutta, Anindita, E-mail: anidu14@gmail.com [College of Environmental Sciences and Engineering, Peking University, Beijing (China); Department of Experimental Hematology, Chittaranjan National Cancer Institute, 37, S.P. Mukherjee Road, Kolkata-700 026 (India); Ray, Manas Ranjan; Banerjee, Anirban [Department of Experimental Hematology, Chittaranjan National Cancer Institute, 37, S.P. Mukherjee Road, Kolkata-700 026 (India)

2012-06-15

The study was undertaken to investigate whether regular cooking with biomass aggravates systemic inflammation and oxidative stress that might result in increase in the risk of developing cardiovascular disease (CVD) in rural Indian women compared to cooking with a cleaner fuel like liquefied petroleum gas (LPG). A total of 635 women (median age 36 years) who cooked with biomass and 452 age-matched control women who cooked with LPG were enrolled. Serum interleukin-6 (IL-6), C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α) and interleukin-8 (IL-8) were measured by ELISA. Generation of reactive oxygen species (ROS) by leukocytes was measured by flow cytometry, and erythrocytic superoxide dismutase (SOD) was measured by spectrophotometry. Hypertension was diagnosed following the Seventh Report of the Joint Committee. Tachycardia was determined as pulse rate > 100 beats per minute. Particulate matter of diameter less than 10 and 2.5 μm (PM{sub 10} and PM{sub 2.5}, respectively) in cooking areas was measured using real-time aerosol monitor. Compared with control, biomass users had more particulate pollution in indoor air, their serum contained significantly elevated levels of IL-6, IL-8, TNF-α and CRP, and ROS generation was increased by 37% while SOD was depleted by 41.5%, greater prevalence of hypertension and tachycardia compared to their LPG-using neighbors. PM{sub 10} and PM{sub 2.5} levels were positively associated with markers of inflammation, oxidative stress and hypertension. Inflammatory markers correlated with raised blood pressure. Cooking with biomass exacerbates systemic inflammation, oxidative stress, hypertension and tachycardia in poor women cooking with biomass fuel and hence, predisposes them to increased risk of CVD development compared to the controls. Systemic inflammation and oxidative stress may be the mechanistic factors involved in the development of CVD. -- Highlights: ► Effect of chronic biomass smoke exposure on

Stress-induced cytokinin synthesis increases drought tolerance through the coordinated regulation of carbon and nitrogen assimilation in rice.

Science.gov (United States)

Reguera, Maria; Peleg, Zvi; Abdel-Tawab, Yasser M; Tumimbang, Ellen B; Delatorre, Carla A; Blumwald, Eduardo

2013-12-01

The effects of water deficit on carbon and nitrogen metabolism were investigated in flag leaves of wild-type and transgenic rice (Oryza sativa japonica 'Kitaake') plants expressing ISOPENTENYLTRANSFERASE (IPT; encoding the enzyme that mediates the rate-limiting step in cytokinin synthesis) under the control of P(SARK), a maturation- and stress-induced promoter. While the wild-type plants displayed inhibition of photosynthesis and nitrogen assimilation during water stress, neither carbon nor nitrogen assimilation was affected by stress in the transgenic P(SARK)::IPT plants. In the transgenic plants, photosynthesis was maintained at control levels during stress and the flag leaf showed increased sucrose (Suc) phosphate synthase activity and reduced Suc synthase and invertase activities, leading to increased Suc contents. The sustained carbon assimilation in the transgenic P(SARK)::IPT plants was well correlated with enhanced nitrate content, higher nitrate reductase activity, and sustained ammonium contents, indicating that the stress-induced cytokinin synthesis in the transgenic plants played a role in maintaining nitrate acquisition. Protein contents decreased and free amino acids increased in wild-type plants during stress, while protein content was preserved in the transgenic plants. Our results indicate that the stress-induced cytokinin synthesis in the transgenic plants promoted sink strengthening through a cytokinin-dependent coordinated regulation of carbon and nitrogen metabolism that facilitates an enhanced tolerance of the transgenic plants to water deficit.

Delaying chloroplast turnover increases water-deficit stress tolerance through the enhancement of nitrogen assimilation in rice.

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Sade, Nir; Umnajkitikorn, Kamolchanok; Rubio Wilhelmi, Maria Del Mar; Wright, Matthew; Wang, Songhu; Blumwald, Eduardo

2018-02-12

Abiotic stress-induced senescence in crops is a process particularly affecting the photosynthetic apparatus, decreasing photosynthetic activity and inducing chloroplast degradation. A pathway for stress-induced chloroplast degradation that involves the CHLOROPLAST VESICULATION (CV) gene was characterized in rice (Oryza sativa) plants. OsCV expression was up-regulated with the age of the plants and when plants were exposed to water-deficit conditions. The down-regulation of OsCV expression contributed to the maintenance of the chloroplast integrity under stress. OsCV-silenced plants displayed enhanced source fitness (i.e. carbon and nitrogen assimilation) and photorespiration, leading to water-deficit stress tolerance. Co-immunoprecipitation, intracellular co-localization, and bimolecular fluorescence demonstrated the in vivo interaction between OsCV and chloroplastic glutamine synthetase (OsGS2), affecting source-sink relationships of the plants under stress. Our results would indicate that the OsCV-mediated chloroplast degradation pathway is involved in the regulation of nitrogen assimilation during stress-induced plant senescence. © The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Endoplasmic reticulum stress increases AT1R mRNA expression via TIA-1-dependent mechanism.

Science.gov (United States)

Backlund, Michael; Paukku, Kirsi; Kontula, Kimmo K; Lehtonen, Jukka Y A

2016-04-20

As the formation of ribonucleoprotein complexes is a major mechanism of angiotensin II type 1 receptor (AT1R) regulation, we sought to identify novel AT1R mRNA binding proteins. By affinity purification and mass spectroscopy, we identified TIA-1. This interaction was confirmed by colocalization of AT1R mRNA and TIA-1 by FISH and immunofluorescence microscopy. In immunoprecipitates of endogenous TIA- 1, reverse transcription-PCR amplified AT1R mRNA. TIA-1 has two binding sites within AT1R 3'-UTR. The binding site proximal to the coding region is glyceraldehyde-3-phosphate dehydrogenase (GAPDH)-dependent whereas the distal binding site is not. TIA-1 functions as a part of endoplasmic reticulum (ER) stress response leading to stress granule (SG) formation and translational silencing. We and others have shown that AT1R expression is increased by ER stress-inducing factors. In unstressed cells, TIA-1 binds to AT1R mRNA and decreases AT1R protein expression. Fluorescence microscopy shows that ER stress induced by thapsigargin leads to the transfer of TIA-1 to SGs. In FISH analysis AT1R mRNA remains in the cytoplasm and no longer colocalizes with TIA-1. Thus, release of TIA-1-mediated suppression by ER stress increases AT1R protein expression. In conclusion, AT1R mRNA is regulated by TIA-1 in a ER stress-dependent manner. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Chronic stress undermines the compensatory sleep efficiency increase in response to sleep restriction in adolescents.

Science.gov (United States)

Astill, Rebecca G; Verhoeven, Dorit; Vijzelaar, Romy L; Van Someren, Eus J W

2013-08-01

To investigate the effects of real-life stress on the sleep of adolescents, we performed a repeated-measures study on actigraphic sleep estimates and subjective measures during one regular school week, two stressful examination weeks and a week's holiday. Twenty-four adolescents aged 17.63 ± 0.10 years (mean ± standard error of the mean) wore actigraphs and completed diaries on subjective stress, fatigue, sleep quality, number of examinations and consumption of caffeine and alcohol for 4 weeks during their final year of secondary school. The resulting almost 500 assessments were analysed using mixed-effect models to estimate the effects of mere school attendance and additional examination stress on sleep estimates and subjective ratings. Total sleep time decreased from 7:38 h ± 12 min during holidays to 6:40 h ± 12 min during a regular school week. This 13% decrease elicited a partial compensation, as indicated by a 3% increase in sleep efficiency and a 6% decrease in the duration of nocturnal awakenings. During examination weeks total sleep time decreased to 6:23 h ± 8 min, but it was now accompanied by a decrease in sleep efficiency and subjective sleep quality and an increase in wake bout duration. In conclusion, school examination stress affects the sleep of adolescents. The compensatory mechanism of more consolidated sleep, as elicited by the sleep restriction associated with mere school attendance, collapsed during 2 weeks of sustained examination stress. © 2013 European Sleep Research Society.

Fear extinction deficits following acute stress associate with increased spine density and dendritic retraction in basolateral amygdala neurons

Science.gov (United States)

Maroun, Mouna; Ioannides, Pericles J.; Bergman, Krista L.; Kavushansky, Alexandra; Holmes, Andrew; Wellman, Cara L.

2013-01-01

Stress-sensitive psychopathologies such as post-traumatic stress disorder are characterized by deficits in fear extinction and dysfunction of corticolimbic circuits mediating extinction. Chronic stress facilitates fear conditioning, impairs extinction, and produces dendritic proliferation in the basolateral amygdala (BLA), a critical site of plasticity for extinction. Acute stress impairs extinction, alters plasticity in the medial prefrontal cortex-to-BLA circuit, and causes dendritic retraction in the medial prefrontal cortex. Here, we examined extinction learning and basolateral amygdala pyramidal neuron morphology in adult male rats following a single elevated platform stress. Acute stress impaired extinction acquisition and memory, and produced dendritic retraction and increased mushroom spine density in basolateral amygdala neurons in the right hemisphere. Unexpectedly, irrespective of stress, rats that underwent fear and extinction testing showed basolateral amygdala dendritic retraction and altered spine density relative to non-conditioned rats, particularly in the left hemisphere. Thus, extinction deficits produced by acute stress are associated with increased spine density and dendritic retraction in basolateral amygdala pyramidal neurons. Furthermore, the finding that conditioning and extinction as such was sufficient to alter basolateral amygdala morphology and spine density illustrates the sensitivity of basolateral amygdala morphology to behavioral manipulation. These findings may have implications for elucidating the role of the amygdala in the pathophysiology of stress-related disorders. PMID:23714419

Do Italian Companies Manage Work-Related Stress Effectively? A Process Evaluation in Implementing the INAIL Methodology.

Science.gov (United States)

Di Tecco, Cristina; Ronchetti, Matteo; Ghelli, Monica; Russo, Simone; Persechino, Benedetta; Iavicoli, Sergio

2015-01-01

Studies on Intervention Process Evaluation are attracting growing attention in the literature on interventions linked to stress and the wellbeing of workers. There is evidence that some elements relating to the process and content of an intervention may have a decisive role in implementing it by facilitating or hindering the effectiveness of the results. This study aimed to provide a process evaluation on interventions to assess and manage risks related to work-related stress using a methodological path offered by INAIL. The final sample is composed of 124 companies participating to an interview on aspects relating to each phase of the INAIL methodological path put in place to implement the intervention. INAIL methodology has been defined as useful in the process of assessing and managing the risks related to work-related stress. Some factors related to the process (e.g., implementation of a preliminary phase, workers' involvement, and use of external consultants) showed a role in significant differences that emerged in the levels of risk, particularly in relation to findings from the preliminary assessment. Main findings provide information on the key aspects of process and content that are useful in implementing an intervention for assessing and managing risks related to work-related stress.

Do Italian Companies Manage Work-Related Stress Effectively? A Process Evaluation in Implementing the INAIL Methodology

Science.gov (United States)

Di Tecco, Cristina; Ronchetti, Matteo; Ghelli, Monica; Russo, Simone; Persechino, Benedetta

2015-01-01

Studies on Intervention Process Evaluation are attracting growing attention in the literature on interventions linked to stress and the wellbeing of workers. There is evidence that some elements relating to the process and content of an intervention may have a decisive role in implementing it by facilitating or hindering the effectiveness of the results. This study aimed to provide a process evaluation on interventions to assess and manage risks related to work-related stress using a methodological path offered by INAIL. The final sample is composed of 124 companies participating to an interview on aspects relating to each phase of the INAIL methodological path put in place to implement the intervention. INAIL methodology has been defined as useful in the process of assessing and managing the risks related to work-related stress. Some factors related to the process (e.g., implementation of a preliminary phase, workers' involvement, and use of external consultants) showed a role in significant differences that emerged in the levels of risk, particularly in relation to findings from the preliminary assessment. Main findings provide information on the key aspects of process and content that are useful in implementing an intervention for assessing and managing risks related to work-related stress. PMID:26504788

Effect of Welding Processes on the Microstructure, Mechanical Properties and Residual Stresses of Plain 9Cr-1Mo Steel Weld Joints

Science.gov (United States)

Nagaraju, S.; Vasantharaja, P.; Brahadees, G.; Vasudevan, M.; Mahadevan, S.

2017-12-01

9Cr-1Mo steel designated as P9 is widely used in the construction of power plants and high-temperature applications. It is chosen for fabricating hexcan fuel subassembly wrapper components of fast breeder reactors. Arc welding processes are generally used for fabricating 9Cr-1Mo steel weld joints. A-TIG welding process is increasingly being adopted by the industries. In the present study, shielded metal arc (SMA), tungsten inert gas (TIG) and A-TIG welding processes are used for fabricating the 9Cr-1Mo steel weld joints of 10 mm thickness. Effect of the above welding processes on the microstructure evolution, mechanical properties and residual stresses of the weld joints has been studied in detail. All the three weld joints exhibited comparable strength and ductility values. 9Cr-1Mo steel weld joint fabricated by SMAW process exhibited lower impact toughness values caused by coarser grain size and inclusions. 9Cr-1Mo steel weld joint fabricated by TIG welding exhibited higher toughness due to finer grain size, while the weld joint fabricated by A-TIG welding process exhibited adequate toughness values. SMA steel weld joint exhibited compressive residual stresses in the weld metal and HAZ, while TIG and A-TIG weld joint exhibited tensile residual stresses in the weld metal and HAZ.

Increased Oxidative Stress Response in Granulocytes from Older Patients with a Hip Fracture May Account for Slow Regeneration

Directory of Open Access Journals (Sweden)

Zhiyong Wang

2014-01-01

Full Text Available Proximal femur fracture, a typical fracture of the elderly, is often associated with morbidity, reduced quality of life, impaired physical function and increased mortality. There exists evidence that responses of the hematopoietic microenvironment to fractures change with age. Therefore, we investigated oxidative stress markers and oxidative stress-related MAPK activation in granulocytes from the young and the elderly with and without fractured long bones. Lipid peroxidation levels were increased in the elderly controls and patients. Aged granulocytes were more sensitive towards oxidative stress induced damage than young granulocytes. This might be due to the basally increased expression of SOD-1 in the elderly, which was not further induced by fractures, as observed in young patients. This might be caused by an altered MAPK activation. In aged granulocytes basal p38 and JNK activities were increased and basal ERK1/2 activity was decreased. Following fracture, JNK activity decreased, while ERK1/2 and p38 activities increased in both age groups. Control experiments with HL60 cells revealed that the observed p38 activation depends strongly on age. Summarizing, we observed age-dependent changes in the oxidative stress response system of granulocytes after fractures, for example, altered MAPK activation and SOD-1 expression. This makes aged granulocytes vulnerable to the stress stimuli of the fracture and following surgery.

High lung volume increases stress failure in pulmonary capillaries

Science.gov (United States)

Fu, Z.; Costello, M. L.; Tsukimoto, K.; Prediletto, R.; Elliott, A. R.; Mathieu-Costello, O.; West, J. B.

1992-01-01

We previously showed that when pulmonary capillaries in anesthetized rabbits are exposed to a transmural pressure (Ptm) of approximately 40 mmHg, stress failure of the walls occurs with disruption of the capillary endothelium, alveolar epithelium, or sometimes all layers. The present study was designed to test whether stress failure occurred more frequently at high than at low lung volumes for the same Ptm. Lungs of anesthetized rabbits were inflated to a transpulmonary pressure of 20 cmH2O, perfused with autologous blood at 32.5 or 2.5 cmH2O Ptm, and fixed by intravascular perfusion. Samples were examined by both transmission and scanning electron microscopy. The results were compared with those of a previous study in which the lung was inflated to a transpulmonary pressure of 5 cmH2O. There was a large increase in the frequency of stress failure of the capillary walls at the higher lung volume. For example, at 32.5 cmH2O Ptm, the number of endothelial breaks per millimeter cell lining was 7.1 +/- 2.2 at the high lung volume compared with 0.7 +/- 0.4 at the low lung volume. The corresponding values for epithelium were 8.5 +/- 1.6 and 0.9 +/- 0.6. Both differences were significant (P less than 0.05). At 52.5 cmH2O Ptm, the results for endothelium were 20.7 +/- 7.6 (high volume) and 7.1 +/- 2.1 (low volume), and the corresponding results for epithelium were 32.8 +/- 11.9 and 11.4 +/- 3.7. At 32.5 cmH2O Ptm, the thickness of the blood-gas barrier was greater at the higher lung volume, consistent with the development of more interstitial edema. Ballooning of the epithelium caused by accumulation of edema fluid between the epithelial cell and its basement membrane was seen at 32.5 and 52.5 cmH2O Ptm. At high lung volume, the breaks tended to be narrower and fewer were oriented perpendicular to the axis of the pulmonary capillaries than at low lung volumes. Transmission and scanning electron microscopy measurements agreed well. Our findings provide a physiological

Residual stress evaluation and curvature behavior of aluminum 7050 peen forming processed; Avaliacao da tensao residual em aluminio 7050 conformado pelo processo peen forming

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Rene Ramos de

2011-07-01

Shot peening is a superficial cold work process used to increase the fatigue life evaluated by residual stress measurements. The peen forming process is a variant of the shot peening process, where a curvature in the plate is obtained by the compression of the grains near to the surface. In this paper, the influence of the parameters such as: pressure of shot, ball shot size and thickness of aluminum 7050 samples with respect to residual stress profile and resulting arc height was studied. The evaluation of the residual stress profile was obtained by sin{sup 2} {psi} method. The results show that the formation of the curvature arc height is proportional to the shot peening pressure, of spheres size and inversely proportional to the thickness of the sample, and that stress concentration factor is larger for samples shot peened with small balls. On final of this paper presents an additional study on micro strain and average crystallite size, which can evaluate the profile of the samples after blasting. (author)

Direct, CMOS In-Line Process Flow Compatible, Sub 100 °C Cu-Cu Thermocompression Bonding Using Stress Engineering

Science.gov (United States)

Panigrahi, Asisa Kumar; Ghosh, Tamal; Kumar, C. Hemanth; Singh, Shiv Govind; Vanjari, Siva Rama Krishna

2018-03-01

Diffusion of atoms across the boundary between two bonding layers is the key for achieving excellent thermocompression Wafer on Wafer bonding. In this paper, we demonstrate a novel mechanism to increase the diffusion across the bonding interface and also shows the CMOS in-line process flow compatible Sub 100 °C Cu-Cu bonding which is devoid of Cu surface treatment prior to bonding. The stress in sputtered Cu thin films was engineered by adjusting the Argon in-let pressure in such a way that one film had a compressive stress while the other film had tensile stress. Due to this stress gradient, a nominal pressure (2 kN) and temperature (75 °C) was enough to achieve a good quality thermocompression bonding having a bond strength of 149 MPa and very low specific contact resistance of 1.5 × 10-8 Ω-cm2. These excellent mechanical and electrical properties are resultant of a high quality Cu-Cu bonding having grain growth between the Cu films across the boundary and extended throughout the bonded region as revealed by Cross-sectional Transmission Electron Microscopy. In addition, reliability assessment of Cu-Cu bonding with stress engineering was demonstrated using multiple current stressing and temperature cycling test, suggests excellent reliable bonding without electrical performance degradation.

Direct, CMOS In-Line Process Flow Compatible, Sub 100 °C Cu-Cu Thermocompression Bonding Using Stress Engineering

Science.gov (United States)

Panigrahi, Asisa Kumar; Ghosh, Tamal; Kumar, C. Hemanth; Singh, Shiv Govind; Vanjari, Siva Rama Krishna

2018-05-01

Diffusion of atoms across the boundary between two bonding layers is the key for achieving excellent thermocompression Wafer on Wafer bonding. In this paper, we demonstrate a novel mechanism to increase the diffusion across the bonding interface and also shows the CMOS in-line process flow compatible Sub 100 °C Cu-Cu bonding which is devoid of Cu surface treatment prior to bonding. The stress in sputtered Cu thin films was engineered by adjusting the Argon in-let pressure in such a way that one film had a compressive stress while the other film had tensile stress. Due to this stress gradient, a nominal pressure (2 kN) and temperature (75 °C) was enough to achieve a good quality thermocompression bonding having a bond strength of 149 MPa and very low specific contact resistance of 1.5 × 10-8 Ω-cm2. These excellent mechanical and electrical properties are resultant of a high quality Cu-Cu bonding having grain growth between the Cu films across the boundary and extended throughout the bonded region as revealed by Cross-sectional Transmission Electron Microscopy. In addition, reliability assessment of Cu-Cu bonding with stress engineering was demonstrated using multiple current stressing and temperature cycling test, suggests excellent reliable bonding without electrical performance degradation.

COMPANY AIKIDO – IT SEEMS TO BE A PRACTICAL METHOD TO REDUCE STRESS AND INCREASE A PERSON’S ENERGY

Directory of Open Access Journals (Sweden)

Andronicus TORP

2016-05-01

Full Text Available Companies are increasingly using methods such as massage, sports, mindfulness, etc. in order for example to improve employee well-being, reduce stress, or increase the energy level of the employees. This article examines, based on a case study, if Aikido may be a practical way to reduce stress and/or increase energy. The empirical study is based on measuring the energy and stress level of the practitioners before and after the practice of Aikido by the use of the ElectroPhotonic Imaging Device developed by Prof. Dr. Korotkov.

Nest ectoparasites increase physiological stress in breeding birds: an experiment.

Science.gov (United States)

Martínez-de la Puente, Josué; Merino, Santiago; Tomás, Gustavo; Moreno, Juan; Morales, Judith; Lobato, Elisa; Martínez, Javier

2011-02-01

Parasites are undoubtedly a biotic factor that produces stress. Heat shock proteins (HSPs) are important molecules buffering cellular damage under adverse conditions. During the breeding season, blue tit Cyanistes caeruleus (L.) adults are affected by blood parasites, nest-dwelling parasites and biting flies, potentially affecting their HSP-mediated responses. Here, we treated females with primaquine to reduce blood parasites and fumigated nests with permethrin to reduce nest-dwelling parasites to test whether these treatments affect HSP60 level during the breeding season. Medicated females, but not controls, had a significant reduction of the intensity of infection by Haemoproteus spp. blood parasites. However, final intensity of infection did not differ significantly between groups, and we did not find an effect of medication on change in HSP60 level. Fumigation reduced the abundance of nest-dwelling parasites (mites, fleas and blowfly larvae) and engorged biting midges in nests. Females breeding in non-fumigated nests increased HSP60 levels during the season more than those breeding in fumigated nests. Furthermore, the change in HSP60 level was positively correlated with the abundance of biting midges. These results show how infections by nest ectoparasites during the breeding period can increase the level of HSPs and suggest that biting midges impose physiological costs on breeding female blue tits. Although plausible, the alternative that biting midges prefer to feed on more stressed birds is poorly supported by previous studies.

Depression, anxiety-like behavior and memory impairment are associated with increased oxidative stress and inflammation in a rat model of social stress.

Science.gov (United States)

Patki, Gaurav; Solanki, Naimesh; Atrooz, Fatin; Allam, Farida; Salim, Samina

2013-11-20

In the present study, we have examined the behavioral and biochemical effect of induction of psychological stress using a modified version of the resident-intruder model for social stress (social defeat). At the end of the social defeat protocol, body weights, food and water intake were recorded, depression and anxiety-like behaviors as well as memory function was examined. Biochemical analysis including oxidative stress measurement, inflammatory markers and other molecular parameters, critical to behavioral effects were examined. We observed a significant decrease in the body weight in the socially defeated rats as compared to the controls. Furthermore, social defeat increased anxiety-like behavior and caused memory impairment in rats (PSocially defeated rats made significantly more errors in long term memory tests (Psocially defeated rats, when compared to control rats. We suggest that social defeat stress alters ERK1/2, IL-6, GLO1, GSR1, CAMKIV, CREB, and BDNF levels in specific brain areas, leading to oxidative stress-induced anxiety-depression-like behaviors and as well as memory impairment in rats. © 2013 Published by Elsevier B.V.

Morphological plasticity of root growth under mild water stress increases water use efficiency without reducing yield in maize

Science.gov (United States)

Cai, Qian; Zhang, Yulong; Sun, Zhanxiang; Zheng, Jiaming; Bai, Wei; Zhang, Yue; Liu, Yang; Feng, Liangshan; Feng, Chen; Zhang, Zhe; Yang, Ning; Evers, Jochem B.; Zhang, Lizhen

2017-08-01

A large yield gap exists in rain-fed maize (Zea mays L.) production in semi-arid regions, mainly caused by frequent droughts halfway through the crop-growing period due to uneven distribution of rainfall. It is questionable whether irrigation systems are economically required in such a region since the total amount of rainfall does generally meet crop requirements. This study aimed to quantitatively determine the effects of water stress from jointing to grain filling on root and shoot growth and the consequences for maize grain yield, above- and below-ground dry matter, water uptake (WU) and water use efficiency (WUE). Pot experiments were conducted in 2014 and 2015 with a mobile rain shelter to achieve conditions of no, mild or severe water stress. Maize yield was not affected by mild water stress over 2 years, while severe stress reduced yield by 56 %. Both water stress levels decreased root biomass slightly but shoot biomass substantially. Mild water stress decreased root length but increased root diameter, resulting in no effect on root surface area. Due to the morphological plasticity in root growth and the increase in root / shoot ratio, WU under water stress was decreased, and overall WUE for both above-ground dry matter and grain yield increased. Our results demonstrate that an irrigation system might be not economically and ecologically necessary because the frequently occurring mild water stress did not reduce crop yield much. The study helps us to understand crop responses to water stress during a critical water-sensitive period (middle of the crop-growing season) and to mitigate drought risk in dry-land agriculture.

Morphological plasticity of root growth under mild water stress increases water use efficiency without reducing yield in maize

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Q. Cai

2017-08-01

Full Text Available A large yield gap exists in rain-fed maize (Zea mays L. production in semi-arid regions, mainly caused by frequent droughts halfway through the crop-growing period due to uneven distribution of rainfall. It is questionable whether irrigation systems are economically required in such a region since the total amount of rainfall does generally meet crop requirements. This study aimed to quantitatively determine the effects of water stress from jointing to grain filling on root and shoot growth and the consequences for maize grain yield, above- and below-ground dry matter, water uptake (WU and water use efficiency (WUE. Pot experiments were conducted in 2014 and 2015 with a mobile rain shelter to achieve conditions of no, mild or severe water stress. Maize yield was not affected by mild water stress over 2 years, while severe stress reduced yield by 56 %. Both water stress levels decreased root biomass slightly but shoot biomass substantially. Mild water stress decreased root length but increased root diameter, resulting in no effect on root surface area. Due to the morphological plasticity in root growth and the increase in root ∕ shoot ratio, WU under water stress was decreased, and overall WUE for both above-ground dry matter and grain yield increased. Our results demonstrate that an irrigation system might be not economically and ecologically necessary because the frequently occurring mild water stress did not reduce crop yield much. The study helps us to understand crop responses to water stress during a critical water-sensitive period (middle of the crop-growing season and to mitigate drought risk in dry-land agriculture.

Coupling image processing and stress analysis for damage identification in a human premolar tooth.

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Andreaus, U; Colloca, M; Iacoviello, D

2011-08-01

Non-carious cervical lesions are characterized by the loss of dental hard tissue at the cement-enamel junction (CEJ). Exceeding stresses are therefore generated in the cervical region of the tooth that cause disruption of the bonds between the hydroxyapatite crystals, leading to crack formation and eventual loss of enamel and the underlying dentine. Damage identification was performed by image analysis techniques and allowed to quantitatively assess changes in teeth. A computerized two-step procedure was generated and applied to the first left maxillary human premolar. In the first step, dental images were digitally processed by a segmentation method in order to identify the damage. The considered morphological properties were the enamel thickness and total area, the number of fragments in which the enamel is chipped. The information retrieved by the data processing of the section images allowed to orient the stress investigation toward selected portions of the tooth. In the second step, a three-dimensional finite element model based on CT images of both the tooth and the periodontal ligament was employed to compare the changes occurring in the stress distributions in normal occlusion and malocclusion. The stress states were analyzed exclusively in the critical zones designated in the first step. The risk of failure at the CEJ and of crack initiation at the dentin-enamel junction through the quantification of first and third principal stresses, von Mises stress, and normal and tangential stresses, were also estimated. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Journaling about stressful events: effects of cognitive processing and emotional expression.

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Ullrich, Philip M; Lutgendorf, Susan K

2002-01-01

The effects of two journaling interventions, one focusing on emotional expression and the other on both cognitive processing and emotional expression, were compared during 1 month of journaling about a stressful or traumatic event. One hundred twenty-two students were randomly assigned to one of three writing conditions: (a) focusing on emotions related to a trauma or stressor, (b) focusing on cognitions and emotions related to a trauma or stressor, or (c) writing factually about media events. Writers focusing on cognitions and emotions developed greater awareness of the positive benefits of the stressful event than the other two groups. This effect was apparently mediated by greater cognitive processing during writing. Writers focusing on emotions alone reported more severe illness symptoms during the study than those in other conditions. This effect appeared to be mediated by a greater focus on negative emotional expression during writing.

Mechanical Characterization of Thermomechanical Matrix Residual Stresses Incurred During MMC Processing

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Castelli, Michael G.

1998-01-01

In recent years, much effort has been spent examining the residual stress-strain states of advanced composites. Such examinations are motivated by a number of significant concerns that affect composite development, processing, and analysis. The room-temperature residual stress states incurred in many advanced composite systems are often quite large and can introduce damage even prior to the first external mechanical loading of the material. These stresses, which are induced during the cooldown following high-temperature consolidation, result from the coefficient of thermal expansion mismatch between the fiber and matrix. Experimental techniques commonly used to evaluate composite internal residual stress states are non-mechanical in nature and generally include forms of x-ray and neutron diffraction. Such approaches are usually complex, involving a number of assumptions and limitations associated with a wide range of issues, including the depth of penetration, the volume of material being assessed, and erroneous effects associated with oriented grains. Furthermore, and more important to the present research, these techniques can assess only "single time" stress in the composite. That is, little, if any, information is obtained that addresses the time-dependent point at which internal stresses begin to accumulate, the manner in which the accumulation occurs, and the presiding relationships between thermoelastic, thermoplastic, and thermoviscous behaviors. To address these critical issues, researchers at the NASA Lewis Research Center developed and implemented an innovative mechanical test technique to examine in real time, the time-dependent thermomechanical stress behavior of a matrix alloy as it went through a consolidation cycle.

Chronic mild stress increases alcohol intake in mice with low dopamine D2 receptor levels.

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Delis, Foteini; Thanos, Panayotis K; Rombola, Christina; Rosko, Lauren; Grandy, David; Wang, Gene-Jack; Volkow, Nora D

2013-02-01

Alcohol use disorders emerge from a complex interaction between environmental and genetic factors. Stress and dopamine D2 receptor levels (DRD2) have been shown to play a central role in alcoholism. To better understand the interactions between DRD2 and stress in ethanol intake behavior, we subjected Drd2 wild-type (+/+), heterozygous (+/-), and knockout (-/-) mice to 4 weeks of chronic mild stress (CMS) and to an ethanol two-bottle choice during CMS weeks 2-4. Prior to and at the end of the experiment, the animals were tested in the forced swim and open field tests. We measured ethanol intake and preference, immobility in the force swim test, and activity in the open field. We show that under no CMS, Drd2+/- and Drd2-/- mice had lower ethanol intake and preference compared with Drd2+/+. Exposure to CMS decreased ethanol intake and preference in Drd2+/+ and increased them in Drd2+/- and Drd2-/- mice. At baseline, Drd2+/- and Drd2-/- mice had significantly lower activity in the open field than Drd2+/+, whereas no genotype differences were observed in the forced swim test. Exposure to CMS increased immobility during the forced swim test in Drd2+/- mice, but not in Drd2+/+ or Drd2-/- mice, and ethanol intake reversed this behavior. No changes were observed in open field test measures. These findings suggest that in the presence of a stressful environment, low DRD2 levels are associated with increased ethanol intake and preference and that under this condition, increased ethanol consumption could be used as a strategy to alleviate negative mood. (PsycINFO Database Record (c) 2013 APA, all rights reserved).

Mediating processes between stress and problematic marijuana use.

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Ketcherside, Ariel; Filbey, Francesca M

2015-06-01

The literature widely reports that stress is associated with marijuana use, yet, to date, the path from stress to marijuana-related problems has not been tested. In this study, we evaluated whether negative affect mediates the relationship between stress and marijuana use. To that end, we tested models to determine mediators between problems with marijuana use (via Marijuana Problem Scale), stress (via Early Life Stress Questionnaire, Perceived Stress Scale), and negative affect (via Beck Depression Inventory; Beck Anxiety Inventory) in 157 current heavy marijuana users. Mediation tests and bootstrap confidence intervals were carried out via the "Mediation" package in R. Depression and anxiety scores both significantly mediated the relationship between perceived stress and problematic marijuana use. Only depression significantly mediated the relationship between early life stress and problematic marijuana use. Early life stress, perceived stress and problematic marijuana use were significant only as independent variables and dependent variables. These findings demonstrate that (1) depression mediated both early life stress and perceived stress, and problematic marijuana use, and, (2) anxiety mediated perceived stress and problematic marijuana use. This mediation analysis represents a strong first step toward understanding the relationship between these variables; however, longitudinal studies are needed to determine causality between these variables. To conclude, addressing concomitant depression and anxiety in those who report either perceived stress or early life stress is important for the prevention of cannabis use disorders. Copyright © 2015. Published by Elsevier Ltd.

Methamphetamine Use among Rural White and Native American Adolescents: An Application of the Stress Process Model

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Eitle, David J.; Eitle, Tamela McNulty

2013-01-01

Methamphetamine use has been identified as having significant adverse health consequences, yet we know little about the correlates of its use. Additionally, research has found that Native Americans are at the highest risk for methamphetamine use. Our exploratory study, informed by the stress process model, examines stress and stress buffering…

Influence of stress on fear memory processes in an aversive differential conditioning paradigm in humans.

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Bentz, Dorothée; Michael, Tanja; Wilhelm, Frank H; Hartmann, Francina R; Kunz, Sabrina; von Rohr, Isabelle R Rudolf; de Quervain, Dominique J-F

2013-07-01

It is widely assumed that learning and memory processes play an important role in the pathogenesis, expression, maintenance and therapy of anxiety disorders, such as phobias or post-traumatic stress disorder (PTSD). Memory retrieval is involved in symptom expression and maintenance of these disorders, while memory extinction is believed to be the underlying mechanism of behavioral exposure therapy of anxiety disorders. There is abundant evidence that stress and stress hormones can reduce memory retrieval of emotional information, whereas they enhance memory consolidation of extinction training. In this study we aimed at investigating if stress affects these memory processes in a fear conditioning paradigm in healthy human subjects. On day 1, fear memory was acquired through a standard differential fear conditioning procedure. On day 2 (24h after fear acquisition), participants either underwent a stressful cold pressor test (CPT) or a control condition, 20 min before memory retrieval testing and extinction training. Possible prolonged effects of the stress manipulation were investigated on day 3 (48 h after fear acquisition), when memory retrieval and extinction were tested again. On day 2, men in the stress group showed a robust cortisol response to stress and showed lower unconditioned stimulus (US) expectancy ratings than men in the control group. This reduction in fear memory retrieval was maintained on day 3. In women, who showed a significantly smaller cortisol response to stress than men, no stress effects on fear memory retrieval were observed. No group differences were observed with respect to extinction. In conclusion, the present study provides evidence that stress can reduce memory retrieval of conditioned fear in men. Our findings may contribute to the understanding of the effects of stress and glucocorticoids on fear symptoms in anxiety disorders and suggest that such effects may be sex-specific. Copyright © 2013 Elsevier Ltd. All rights reserved.

High-anxious individuals show increased chronic stress burden, decreased protective immunity, and increased cancer progression in a mouse model of squamous cell carcinoma.

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Firdaus S Dhabhar

Full Text Available In spite of widespread anecdotal and scientific evidence much remains to be understood about the long-suspected connection between psychological factors and susceptibility to cancer. The skin is the most common site of cancer, accounting for nearly half of all cancers in the US, with approximately 2-3 million cases of non-melanoma cancers occurring each year worldwide. We hypothesized that a high-anxious, stress-prone behavioral phenotype would result in a higher chronic stress burden, lower protective-immunity, and increased progression of the immuno-responsive skin cancer, squamous cell carcinoma. SKH1 mice were phenotyped as high- or low-anxious at baseline, and subsequently exposed to ultraviolet-B light (1 minimal erythemal dose (MED, 3 times/week, 10-weeks. The significant strengths of this cancer model are that it uses a normal, immunocompetent, outbred strain, without surgery/injection of exogenous tumor cells/cell lines, and produces lesions that resemble human tumors. Tumors were counted weekly (primary outcome, and tissues collected during early and late phases of tumor development. Chemokine/cytokine gene-expression was quantified by PCR, tumor-infiltrating helper (Th, cytolytic (CTL, and regulatory (Treg T cells by immunohistochemistry, lymph node T and B cells by flow cytometry, adrenal and plasma corticosterone and tissue vascular-endothelial-growth-factor (VEGF by ELISA. High-anxious mice showed a higher tumor burden during all phases of tumor development. They also showed: higher corticosterone levels (indicating greater chronic stress burden, increased CCL22 expression and Treg infiltration (increased tumor-recruited immuno-suppression, lower CTACK/CCL27, IL-12, and IFN-γ gene-expression and lower numbers of tumor infiltrating Th and CTLs (suppressed protective immunity, and higher VEGF concentrations (increased tumor angiogenesis/invasion/metastasis. These results suggest that the deleterious effects of high trait anxiety

Dietary toxins, endoplasmic reticulum (ER) stress and diabetes.

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Hettiarachchi, Kalindi D; Zimmet, Paul Z; Myers, Mark A

2008-05-01

The incidence of Type 1 diabetes has been increasing at a rate too rapid to be due to changes in genetic risk. Instead changes in environmental factors are the likely culprit. The endoplasmic reticulum (ER) plays an important role in the production of newly synthesized proteins and interference with these processes leads to ER stress. The insulin-producing beta cells are particularly prone to ER stress as a result of their heavy engagement in insulin production. Increasing evidence suggests ER stress is central to initiation and progression of Type 1 diabetes. An early environmental exposure, such as toxins and viral infections, can impart a significant physiological load on beta cells to initiate abnormal processing of proinsulin, ER stress and insulin secretory defects. Release of altered proinsulin from the beta cells early in life may trigger autoimmunity in those with genetic susceptibility leading to cytokine-induced nitric oxide production and so exacerbating ER stress in beta cells, ultimately leading to apoptosis of beta cells and diabetes. Here we suggest that ER stress is an inherent cause of beta cell dysfunction and environmental factors, in particular dietary toxins derived from Streptomyces in infected root vegetables, can impart additional stress that aggravates beta cell death and progression to diabetes. Furthermore, we propose that the increasing incidence of Type 1 diabetes may be accounted for by increased dietary exposure to ER-stress-inducing Streptomyces toxins.

DETECTING FOREST STRESS AND DECLINE IN RESPONSE TO INCREASING RIVER FLOW IN SOUTHWEST FLORIDA, USA

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Forest stress and decline resulting from increased river flows were investigated in Myakka River State Park (MRSP), Florida, USA. Since 1977, land-use changes around the upper Myakka River watershed have resulted in significant increases in water entering the river, which have...

Interrelationships between trait anxiety, situational stress and mental effort predict phonological processing efficiency, but not effectiveness.

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Edwards, Elizabeth J; Edwards, Mark S; Lyvers, Michael

2016-08-01

Attentional control theory (ACT) describes the mechanisms associated with the relationship between anxiety and cognitive performance. We investigated the relationship between cognitive trait anxiety, situational stress and mental effort on phonological performance using a simple (forward-) and complex (backward-) word span task. Ninety undergraduate students participated in the study. Predictor variables were cognitive trait anxiety, indexed using questionnaire scores; situational stress, manipulated using ego threat instructions; and perceived level of mental effort, measured using a visual analogue scale. Criterion variables (a) performance effectiveness (accuracy) and (b) processing efficiency (accuracy divided by response time) were analyzed in separate multiple moderated-regression analyses. The results revealed (a) no relationship between the predictors and performance effectiveness, and (b) a significant 3-way interaction on processing efficiency for both the simple and complex tasks, such that at higher effort, trait anxiety and situational stress did not predict processing efficiency, whereas at lower effort, higher trait anxiety was associated with lower efficiency at high situational stress, but not at low situational stress. Our results were in full support of the assumptions of ACT and implications for future research are discussed. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Aerobic exercise increases resistance to oxidative stress in sedentary older middle-aged adults. A pilot study.

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Done, Aaron J; Traustadóttir, Tinna

2016-12-01

Older individuals who exercise regularly exhibit greater resistance to oxidative stress than their sedentary peers, suggesting that exercise can modify age-associated loss of resistance to oxidative stress. However, we recently demonstrated that a single bout of exercise confers protection against a subsequent oxidative challenge in young, but not older adults. We therefore hypothesized that repeated bouts of exercise would be needed to increase resistance to an oxidative challenge in sedentary older middle-aged adults. Sedentary older middle-aged men and women (50-63 years, n = 11) participated in an 8-week exercise intervention. Maximal oxygen consumption was measured before and after the intervention. The exercise intervention consisted of three sessions per week, for 45 min at an intensity corresponding to 70-85 % maximal heart rate (HR max ). Resistance to oxidative stress was measured by F 2 -isoprostane response to a forearm ischemia/reperfusion (I/R) trial. Each participant underwent the I/R trial before and after the exercise intervention. The intervention elicited a significant increase in maximal oxygen consumption (VO 2max ) (P exercise intervention (time-by-trial interaction, P = 0.043). Individual improvements in aerobic fitness were associated with greater improvements in the F 2 -isoprostane response (r = -0.761, P = 0.011), further supporting the role of aerobic fitness in resistance to oxidative stress. These data demonstrate that regular exercise with improved fitness leads to increased resistance to oxidative stress in older middle-aged adults and that this measure is modifiable in previously sedentary individuals.

Increased Nitroxidative Stress Promotes Mitochondrial Dysfunction in Alcoholic and Nonalcoholic Fatty Liver Disease

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Byoung-Joon Song

2013-01-01

Full Text Available Increased nitroxidative stress causes mitochondrial dysfunctions through oxidative modifications of mitochondrial DNA, lipids, and proteins. Persistent mitochondrial dysfunction sensitizes the target cells/organs to other pathological risk factors and thus ultimately contributes to the development of more severe disease states in alcoholic and nonalcoholic fatty liver disease. The incidences of nonalcoholic fatty liver disease continuously increase due to high prevalence of metabolic syndrome including hyperlipidemia, hypercholesterolemia, obesity, insulin resistance, and diabetes. Many mitochondrial proteins including the enzymes involved in fat oxidation and energy supply could be oxidatively modified (including S-nitrosylation/nitration under increased nitroxidative stress and thus inactivated, leading to increased fat accumulation and ATP depletion. To demonstrate the underlying mechanism(s of mitochondrial dysfunction, we employed a redox proteomics approach using biotin-N-maleimide (biotin-NM as a sensitive biotin-switch probe to identify oxidized Cys residues of mitochondrial proteins in the experimental models of alcoholic and acute liver disease. The aims of this paper are to briefly describe the mechanisms, functional consequences, and detection methods of mitochondrial dysfunction. We also describe advantages and limitations of the Cys-targeted redox proteomics method with alternative approaches. Finally, we discuss various applications of this method in studying oxidatively modified mitochondrial proteins in extrahepatic tissues or different subcellular organelles and translational research.

Attenuated flow‐induced dilatation of middle cerebral arteries is related to increased vascular oxidative stress in rats on a short‐term high salt diet

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Cosic, Anita; Jukic, Ivana; Stupin, Ana; Mihalj, Martina; Mihaljevic, Zrinka; Novak, Sanja; Vukovic, Rosemary

2016-01-01

Key points Recent studies have shown that high salt (HS) intake leads to endothelial dysfunction and impaired vascular reactivity in different vascular beds in both animal and human models, due to increased oxidative stress.The objective of this study was to assess vascular response to flow‐induced dilatation (FID) and to elucidate the role of vascular oxidative stress/antioxidative capacity in middle cerebral arteries (MCAs) of HS‐fed rats in vitro.The novelty of this study is in demonstrating impaired flow‐induced dilatation of MCAs and down‐regulation of vascular antioxidant genes with HS intake, leading to increased levels of oxidative stress in blood vessels and peripheral lymph organs, which together contribute to impaired FID.In addition, results show increased oxidative stress in leukocytes of peripheral lymph organs, suggesting the occurrence of inflammatory processes due to HS intake.Recirculation of leukocytes might additionally increase vascular oxidative stress in vivo. Abstract The aim of this study was to determine flow‐induced dilatation (FID) and the role of oxidative stress/antioxidative capacity in isolated, pressurized middle cerebral arteries (MCAs) of high salt (HS)‐fed rats. Healthy male Sprague‐Dawley rats (11 weeks old) were fed low salt (0.4% NaCl; LS group) or high salt (4% NaCl; HS group) diets for 1 week. Reactivity of MCAs in response to stepwise increases in pressure gradient (Δ10–Δ100 mmHg) was determined in the absence or presence of the superoxide dismutase (SOD) mimetic TEMPOL and/or the nitric oxide synthases (NOS) inhibitor N ω‐nitro‐l‐arginine methyl ester (l‐name). mRNA levels of antioxidative enzymes, NAPDH‐oxidase components, inducible (iNOS) and endothelial nitric oxide synthases (eNOS) were determined by quantitative real‐time PCR. Blood pressure (BP), antioxidant enzymes activity, oxidative stress in peripheral leukocytes, lipid peroxidation products and the antioxidant capacity of plasma

Process Modelling of Curing Process-Induced Internal Stress and Deformation of Composite Laminate Structure with Elastic and Viscoelastic Models

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Li, Dongna; Li, Xudong; Dai, Jianfeng

2018-06-01

In this paper, two kinds of transient models, the viscoelastic model and the linear elastic model, are established to analyze the curing deformation of the thermosetting resin composites, and are calculated by COMSOL Multiphysics software. The two models consider the complicated coupling between physical and chemical changes during curing process of the composites and the time-variant characteristic of material performance parameters. Subsequently, the two proposed models are implemented respectively in a three-dimensional composite laminate structure, and a simple and convenient method of local coordinate system is used to calculate the development of residual stresses, curing shrinkage and curing deformation for the composite laminate. Researches show that the temperature, degree of curing (DOC) and residual stresses during curing process are consistent with the study in literature, so the curing shrinkage and curing deformation obtained on these basis have a certain referential value. Compared the differences between the two numerical results, it indicates that the residual stress and deformation calculated by the viscoelastic model are more close to the reference value than the linear elastic model.

Anticipatory stress restores decision-making deficits in heavy drinkers by increasing sensitivity to losses.

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Gullo, Matthew J; Stieger, Adam A

2011-09-01

Substance abusers are characterized by hypersensitivity to reward. This leads to maladaptive decisions generally, as well as those on laboratory-based decision-making tasks, such as the Iowa Gambling Task (IGT). Negative affect has also been shown to disrupt the decision-making of healthy individuals, particularly decisions made under uncertainty. Neuropsychological theories of learning, including the Somatic Marker Hypothesis (SMH), argue this occurs by amplifying affective responses to punishment. In substance abusers, this might serve to rebalance their sensitivity to reward with punishment, and improve decision-making. Before completing the IGT, 45 heavy and 47 light drinkers were randomly assigned to a control condition, or led to believe they had to give a stressful public speech. IGT performance was analyzed with the Expectancy-Valence (EV) learning model. Working memory and IQ were also assessed. Heavy drinkers made more disadvantageous decisions than light drinkers, due to higher attention to gains (versus losses) on the IGT. Anticipatory stress increased participants' attention to losses, significantly improving heavy drinkers' decision-making. Anticipatory stress increased attention to losses, effectively restoring decision-making deficits in heavy drinkers by rebalancing their reward sensitivity with punishment sensitivity. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Changes in salivary microbiota increase volatile sulfur compounds production in healthy male subjects with academic-related chronic stress.

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Bruno Dias Nani

Full Text Available To investigate the associations among salivary bacteria, oral emanations of volatile sulfur compounds, and academic-related chronic stress in healthy male subjects.Seventy-eight healthy male undergraduate dental students were classified as stressed or not by evaluation of burnout, a syndrome attributed to academic-related chronic stress. This evaluation was carried out using the Maslach Burnout Inventory-Student Survey questionnaire. Oral emanations of hydrogen sulfide, methyl mercaptan, and dimethyl sulfide were measured using an Oral Chroma™ portable gas chromatograph. The amounts in saliva of total bacteria and seven bacteria associated with halitosis were quantified by qPCR. The in vitro production of H2S by S. moorei and/or F. nucleatum was also measured with the Oral Chroma™ instrument.The stressed students group showed increased oral emanations of hydrogen sulfide and dimethyl sulfide, together with higher salivary Solobacterium moorei levels (p < 0.05, Mann Whitney test. There were moderate positive correlations between the following pairs of variables: Fusobacterium nucleatum and S. moorei; F. nucleatum and hydrogen sulfide; Tannerella forsythia and F. nucleatum; T. forsythia and S. moorei. These correlations only occurred for the stressed group (p < 0.05, Spearman correlation. The in vitro experiment demonstrated that S. moorei increased H2S production by F. nucleatum (p < 0.05, ANOVA and Tukey's test.The increased amount of S. moorei in saliva, and its coexistence with F. nucleatum and T. forsythia, seemed to be responsible for increased oral hydrogen sulfide in the healthy male stressed subjects.

Oral sucrose for heel lance increases adenosine triphosphate use and oxidative stress in preterm neonates.

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Asmerom, Yayesh; Slater, Laurel; Boskovic, Danilo S; Bahjri, Khaled; Holden, Megan S; Phillips, Raylene; Deming, Douglas; Ashwal, Stephen; Fayard, Elba; Angeles, Danilyn M

2013-07-01

To examine the effects of sucrose on pain and biochemical markers of adenosine triphosphate (ATP) degradation and oxidative stress in preterm neonates experiencing a clinically required heel lance. Preterm neonates that met study criteria (n = 131) were randomized into 3 groups: (1) control; (2) heel lance treated with placebo and non-nutritive sucking; and (3) heel lance treated with sucrose and non-nutritive sucking. Plasma markers of ATP degradation (hypoxanthine, xanthine, and uric acid) and oxidative stress (allantoin) were measured before and after the heel lance. Pain was measured with the Premature Infant Pain Profile. Data were analyzed by the use of repeated-measures ANOVA and Spearman rho. We found significant increases in plasma hypoxanthine and uric acid over time in neonates who received sucrose. We also found a significant negative correlation between pain scores and plasma allantoin concentration in a subgroup of neonates who received sucrose. A single dose of oral sucrose, given before heel lance, significantly increased ATP use and oxidative stress in premature neonates. Because neonates are given multiple doses of sucrose per day, randomized trials are needed to examine the effects of repeated sucrose administration on ATP degradation, oxidative stress, and cell injury. Copyright © 2013 Mosby, Inc. All rights reserved.

Atmospheric-Induced Stress Corrosion Cracking of Grade 2205 Duplex Stainless Steel—Effects of 475 °C Embrittlement and Process Orientation

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Cem Örnek

2016-07-01

Full Text Available The effect of 475 °C embrittlement and microstructure process orientation on atmospheric-induced stress corrosion cracking (AISCC of grade 2205 duplex stainless steel has been investigated. AISCC tests were carried out under salt-laden, chloride-containing deposits, on U-bend samples manufactured in rolling (RD and transverse directions (TD. The occurrence of selective corrosion and stress corrosion cracking was observed, with samples in TD displaying higher propensity towards AISCC. Strains and tensile stresses were observed in both ferrite and austenite, with similar magnitudes in TD, whereas, larger strains and stresses in austenite in RD. The occurrence of 475 °C embrittlement was related to microstructural changes in the ferrite. Exposure to 475 °C heat treatment for 5 to 10 h resulted in better AISCC resistance, with spinodal decomposition believed to enhance the corrosion properties of the ferrite. The austenite was more susceptible to ageing treatments up to 50 h, with the ferrite becoming more susceptible with ageing in excess of 50 h. Increased susceptibility of the ferrite may be related to the formation of additional precipitates, such as R-phase. The implications of heat treatment at 475 °C and the effect of process orientation are discussed in light of microstructure development and propensity to AISCC.

Oxidative Stress is Increased in Serum from Mexican Patients with Relapsing-Remitting Multiple Sclerosis

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Genaro Gabriel Ortiz

2009-01-01

Full Text Available Objective: To determine the oxidative stress markers in serum from patients with relapsing-remitting multiple sclerosis. Methods: Blood samples from healthy controls and 22 patients 15 women (7 aged from 20 to 30 and 8 were > 40 years old and 7 men (5 aged from 20 to 30 and 2 were > 40 years old fulfilling the McDonald Criteria and classified as having Relapsing-Remitting Multiple Sclerosis accordingly with Lublin were collected for oxidative stress markers quantification. Results: Nitric oxide metabolites (nitrates/nitrites, lipid peroxidation products (malondialdehyde plus 4-hidroxialkenals, and glutathione peroxidase activity were significantly increased in serum of subjects with relapsing-remitting multiple sclerosis in comparison with that of healthy controls. These data support the hypothesis that multiple sclerosis is a component closely linked to oxidative stress.

Workplace Flexibility and Daily Stress Processes in Hotel Employees and their Children.

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Almeida, David M; Davis, Kelly D

2011-11-01

Our research aims to understand the consequences of inadequate workplace flexibility through the lens of daily stress processes. Using a sample of hourly hotel employees with children aged 10 to 18 who participated in a daily diary study, we compared workers with low and high flexibility on stressor exposure, reactivity, and transmission. Our findings showed a consistent pattern of hourly workers with low flexibility having greater exposure to work stressors in general and to work place arguments in particular. Workers with low flexibility were also more emotional and physically reactive to work stressors. There was some evidence of stressor transmission to children when parents had low flexibility. Increasing workplace flexibility could serve as a protective factor in exposure and reactivity to stressors that are experienced in daily life.

Mutant HFE H63D Protein Is Associated with Prolonged Endoplasmic Reticulum Stress and Increased Neuronal Vulnerability*

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Liu, Yiting; Lee, Sang Y.; Neely, Elizabeth; Nandar, Wint; Moyo, Mthabisi; Simmons, Zachary; Connor, James R.

2011-01-01

A specific polymorphism in the hemochromatosis (HFE) gene, H63D, is over-represented in neurodegenerative disorders such as amyotrophic lateral sclerosis and Alzheimer disease. Mutations of HFE are best known as being associated with cellular iron overload, but the mechanism by which HFE H63D might increase the risk of neuron degeneration is unclear. Here, using an inducible expression cell model developed from a human neuronal cell line SH-SY5Y, we reported that the presence of the HFE H63D protein activated the unfolded protein response (UPR). This response was followed by a persistent endoplasmic reticulum (ER) stress, as the signals of UPR sensors attenuated and followed by up-regulation of caspase-3 cleavage and activity. Our in vitro findings were recapitulated in a transgenic mouse model carrying Hfe H67D, the mouse equivalent of the human H63D mutation. In this model, UPR activation was detected in the lumbar spinal cord at 6 months then declined at 12 months in association with increased caspase-3 cleavage. Moreover, upon the prolonged ER stress, the number of cells expressing HFE H63D in early apoptosis was increased moderately. Cell proliferation was decreased without increased cell death. Additionally, despite increased iron level in cells carrying HFE H63D, it appeared that ER stress was not responsive to the change of cellular iron status. Overall, our studies indicate that the HFE H63D mutant protein is associated with prolonged ER stress and chronically increased neuronal vulnerability. PMID:21349849

Development of intergranular thermal residual stresses in beryllium during cooling from processing temperatures

Energy Technology Data Exchange (ETDEWEB)

Brown, D.W. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)], E-mail: dbrown@lanl.gov; Sisneros, T.A.; Clausen, B.; Abeln, S.; Bourke, M.A.M.; Smith, B.G.; Steinzig, M.L.; Tome, C.N.; Vogel, S.C. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2009-02-15

The intergranular thermal residual stresses in texture-free solid polycrystalline beryllium were determined by comparison of crystallographic lattice parameters in solid and powder samples measured by neutron diffraction during cooling from 800 deg. C. The internal stresses are not significantly different from zero >575 deg. C and increase nearly linearly <525 deg. C. At room temperature, the c axis of an average grain is under {approx}200 MPa of compressive internal stress, and the a axis is under 100 MPa of tensile stress. For comparison, the stresses have also been calculated using an Eshelby-type polycrystalline model. The measurements and calculations agree very well when temperature dependence of elastic constants is accounted for, and no plastic relaxation is allowed in the model.

Increases in anxiety-like behavior induced by acute stress are reversed by ethanol in adolescent but not adult rats.

Science.gov (United States)

Varlinskaya, Elena I; Spear, Linda P

2012-01-01

Repeated exposure to stressors has been found to increase anxiety-like behavior in laboratory rodents, with the social anxiety induced by repeated restraint being extremely sensitive to anxiolytic effects of ethanol in both adolescent and adult rats. No studies, however, have compared social anxiogenic effects of acute stress or the capacity of ethanol to reverse this anxiety in adolescent and adult animals. Therefore, the present study was designed to investigate whether adolescent [postnatal day (P35)] Sprague-Dawley rats differ from their adult counterparts (P70) in the impact of acute restraint stress on social anxiety and in their sensitivity to the social anxiolytic effects of ethanol. Animals were restrained for 90 min, followed by examination of stress- and ethanol-induced (0, 0.25, 0.5, 0.75, and 1 g/kg) alterations in social behavior using a modified social interaction test in a familiar environment. Acute restraint stress increased anxiety, as indexed by reduced levels of social investigation at both ages, and decreased social preference among adolescents. These increases in anxiety were dramatically reversed among adolescents by acute ethanol. No anxiolytic-like effects of ethanol emerged following restraint stress in adults. The social suppression seen in response to higher doses of ethanol was reversed by restraint stress in animals of both ages. To the extent that these data are applicable to humans, the results of the present study provide some experimental evidence that stressful life events may increase the attractiveness of alcohol as an anxiolytic agent for adolescents. Copyright © 2011 Elsevier Inc. All rights reserved.

Fear extinction deficits following acute stress associate with increased spine density and dendritic retraction in basolateral amygdala neurons.

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Maroun, Mouna; Ioannides, Pericles J; Bergman, Krista L; Kavushansky, Alexandra; Holmes, Andrew; Wellman, Cara L

2013-08-01

Stress-sensitive psychopathologies such as post-traumatic stress disorder are characterized by deficits in fear extinction and dysfunction of corticolimbic circuits mediating extinction. Chronic stress facilitates fear conditioning, impairs extinction, and produces dendritic proliferation in the basolateral amygdala (BLA), a critical site of plasticity for extinction. Acute stress impairs extinction, alters plasticity in the medial prefrontal cortex-to-BLA circuit, and causes dendritic retraction in the medial prefrontal cortex. Here, we examined extinction learning and basolateral amygdala pyramidal neuron morphology in adult male rats following a single elevated platform stress. Acute stress impaired extinction acquisition and memory, and produced dendritic retraction and increased mushroom spine density in basolateral amygdala neurons in the right hemisphere. Unexpectedly, irrespective of stress, rats that underwent fear and extinction testing showed basolateral amygdala dendritic retraction and altered spine density relative to non-conditioned rats, particularly in the left hemisphere. Thus, extinction deficits produced by acute stress are associated with increased spine density and dendritic retraction in basolateral amygdala pyramidal neurons. Furthermore, the finding that conditioning and extinction as such was sufficient to alter basolateral amygdala morphology and spine density illustrates the sensitivity of basolateral amygdala morphology to behavioral manipulation. These findings may have implications for elucidating the role of the amygdala in the pathophysiology of stress-related disorders. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Effects of a process-based cognitive training intervention for patients with stress-related exhaustion.

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Gavelin, Hanna Malmberg; Boraxbekk, Carl-Johan; Stenlund, Therese; Järvholm, Lisbeth Slunga; Neely, Anna Stigsdotter

2015-01-01

Stress-related exhaustion has been linked to a pattern of selective cognitive impairments, mainly affecting executive functioning, attention and episodic memory. Little is known about potential treatments of these cognitive deficits. The purpose of this study was to evaluate the effects of a process-based cognitive training intervention, designed to target the specific cognitive impairments associated with stress-related exhaustion. To this end, patients diagnosed with exhaustion disorder (ED) were randomized to either a multimodal stress rehabilitation program with the addition of a process-based cognitive training intervention (training group, n = 27) or a treatment-as-usual control condition, consisting of multimodal stress rehabilitation with no additional training (control group, n = 32). Treatment effects were evaluated through an extensive cognitive test battery, assessing both near and far transfer effects, as well as self-report forms regarding subjective cognitive complaints and burnout levels. Results showed pronounced training-related improvements on the criterion updating task (p effects to updating (p = 0.01) and episodic memory (p = 0.04). Also, the trained group reported less subjective memory complaints (p = 0.02) and levels of burnout decreased for both groups, but more so for the trained group (p = 0.04), following the intervention. These findings suggest that process-based cognitive training may be a viable method to address the cognitive impairments associated with ED.

Activation of NADPH oxidase mediates increased endoplasmic reticulum stress and left ventricular remodeling after myocardial infarction in rabbits.

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Li, Bao; Tian, Jing; Sun, Yi; Xu, Tao-Rui; Chi, Rui-Fang; Zhang, Xiao-Li; Hu, Xin-Ling; Zhang, Yue-An; Qin, Fu-Zhong; Zhang, Wei-Fang

2015-05-01

Nicotinamide adenine dinucleotide 3-phosphate (NADPH) oxidase activity and endoplasmic reticulum (ER) stress are increased after myocardial infarction (MI). In this study, we proposed to test whether activation of the NADPH oxidase in the remote non-infarcted myocardium mediates ER stress and left ventricular (LV) remodeling after MI. Rabbits with MI or sham operation were randomly assigned to orally receive an NADPH oxidase inhibitor apocynin or placebo for 30 days. The agents were administered beginning at 1 week after surgery. MI rabbits exhibited decreases in LV fractional shortening, LV ejection fraction and the first derivative of the LV pressure rise, which were abolished by apocynin treatment. NADPH oxidase Nox2 protein and mRNA expressions were increased in the remote non-infarcted myocardium after MI. Immunolabeling further revealed that Nox2 was increased in cardiac myocytes in the remote myocardium. The apocynin treatment prevented increases in the Nox2 expression, NADPH oxidase activity, oxidative stress, myocyte apoptosis and GRP78, CHOP and cleaved caspase 12 protein expression in the remote myocardium. The apocynin treatment also attenuated increases in myocyte diameter and cardiac fibrosis. In cultured H9C2 cardiomyocytes exposed to angiotensin II, an important stimulus for post-MI remodeling, Nox2 knockdown with siRNA significantly inhibited angiotensin II-induced NADPH oxidase activation, reactive oxygen species and GRP78 and CHOP protein expression. We conclude that NADPH oxidase inhibition attenuates increased ER stress in the remote non-infarcted myocardium and LV remodeling late after MI in rabbits. These findings suggest that the activation of NADPH oxidase in the remote non-infarcted myocardium mediates increased ER stress, contributing to myocyte apoptosis and LV remodeling after MI. Copyright © 2015 Elsevier B.V. All rights reserved.

Mitochondrial dysfunction increases oxidative stress and decreases chronological life span in fission yeast.

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Alice Zuin

Full Text Available BACKGROUND: Oxidative stress is a probable cause of aging and associated diseases. Reactive oxygen species (ROS originate mainly from endogenous sources, namely the mitochondria. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed the effect of aerobic metabolism on oxidative damage in Schizosaccharomyces pombe by global mapping of those genes that are required for growth on both respiratory-proficient media and hydrogen-peroxide-containing fermentable media. Out of a collection of approximately 2700 haploid yeast deletion mutants, 51 were sensitive to both conditions and 19 of these were related to mitochondrial function. Twelve deletion mutants lacked components of the electron transport chain. The growth defects of these mutants can be alleviated by the addition of antioxidants, which points to intrinsic oxidative stress as the origin of the phenotypes observed. These respiration-deficient mutants display elevated steady-state levels of ROS, probably due to enhanced electron leakage from their defective transport chains, which compromises the viability of chronologically-aged cells. CONCLUSION/SIGNIFICANCE: Individual mitochondrial dysfunctions have often been described as the cause of diseases or aging, and our global characterization emphasizes the primacy of oxidative stress in the etiology of such processes.

Boosting recovery rather than buffering reactivity: Higher stress-induced oxytocin secretion is associated with increased cortisol reactivity and faster vagal recovery after acute psychosocial stress.

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Engert, Veronika; Koester, Anna M; Riepenhausen, Antje; Singer, Tania

2016-12-01

Animal models and human studies using paradigms designed to stimulate endogenous oxytocin release suggest a stress-buffering role of oxytocin. We here examined the involvement of stress-induced peripheral oxytocin secretion in reactivity and recovery phases of the human psychosocial stress response. Healthy male and female participants (N=114) were subjected to a standardized laboratory stressor, the Trier Social Stress Test. In addition to plasma oxytocin, cortisol was assessed as a marker of hypothalamic-pituitary-adrenal (HPA-) axis activity, alpha-amylase and heart rate as markers of sympathetic activity, high frequency heart rate variability as a marker of vagal tone and self-rated anxiety as an indicator of subjective stress experience. On average, oxytocin levels increased by 51% following psychosocial stress. The stress-induced oxytocin secretion, however, did not reduce stress reactivity. To the contrary, higher oxytocin secretion was associated with greater cortisol reactivity and peak cortisol levels in both sexes. In the second phase of the stress response the opposite pattern was observed, with higher oxytocin secretion associated with faster vagal recovery. We suggest that after an early stage of oxytocin and HPA-axis co-activation, the stress-reducing action of oxytocin unfolds. Due to the time lag it manifests as a recovery-boosting rather than a reactivity-buffering effect. By reinforcing parasympathetic autonomic activity, specifically during stress recovery, oxytocin may provide an important protective function against the health-compromising effects of sustained stress. Copyright © 2016 Elsevier Ltd. All rights reserved.

Contrasting extremes in water-related stresses determine species survival

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Bartholomeus, R. P.; Witte, J. P. M.; van Bodegom, P. M.; van Dam, J. C.; Aerts, R.

2012-04-01

In temperate climates, soil moisture, in concert with nutrient availability and soil acidity, is the most important environmental filter in determining local plant species composition, as it determines the availability of both oxygen and water to plant roots. These resources are indispensable for meeting the physiological demands of plants. Especially the occurrence of both excessive dry and wet moisture conditions at a particular site has strong implications for the survival of species, because plants need traits that allow them to respond to such counteracting conditions. However, adapting to one stress may go at the cost of the other, i.e. there exists a trade-off in the tolerance for wet conditions and the tolerance for dry conditions. Until now, both large-scale (global) and plot-scale effects of soil moisture conditions on plant species composition have mostly been investigated through indirect environmental measures, which do not include the key soil physical and plant physiological processes in the soil-plant-atmosphere system. Moreover, researchers only determined effects of one of the water-related stresses, i.e. either oxygen or drought stress. In order to quantify both oxygen and drought stress with causal measures, we focused on interacting meteorological, soil physical, microbial, and plant physiological processes in the soil-plant-atmosphere system. We simulated these plant stresses with a novel, process-based approach, incorporating in detail the interacting processes in the soil-plant-atmosphere interface. High variability and extremes in resource availability can be highly detrimental to plant species ('you can only die once'). We show that co-occurrence of oxygen and drought stress reduces the percentage of specialists within a vegetation plot. The percentage of non-specialists within a vegetation plot, however, decreases significantly with increasing stress as long as only one of the stresses prevails, but increases significantly with an

Effects of Stress and Working Memory Capacity on Foreign Language Readers' Inferential Processing during Comprehension

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Rai, Manpreet K.; Loschky, Lester C.; Harris, Richard Jackson; Peck, Nicole R.; Cook, Lindsay G.

2011-01-01

Although stress is frequently claimed to impede foreign language (FL) reading comprehension, it is usually not explained how. We investigated the effects of stress, working memory (WM) capacity, and inferential complexity on Spanish FL readers' inferential processing during comprehension. Inferences, although necessary for reading comprehension,…

Relationships between atypical sensory processing patterns, maladaptive behaviour and maternal stress in Spanish children with autism spectrum disorder.

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Nieto, C; López, B; Gandía, H

2017-12-01

This study investigated sensory processing in a sample of Spanish children with autism spectrum disorder (ASD). Specifically, the study aimed to explore (1) the prevalence and distribution of atypical sensory processing patterns, (2) the relationship between adaptive and maladaptive behaviour with atypical sensory processing and (3) the possible relationship between sensory subtype and maternal stress. The short sensory profile 2 (Dunn 2014) and the vineland adaptive behavior scale (Sparrow et al. 1984) were administered to examine the sensory processing difficulties and maladaptive behaviours of 45 children with ASD aged 3 to 14; their mothers also completed the parenting stress index-short form (Abidin 1995). Atypical sensory features were found in 86.7% of the children; avoider and sensor being the two most common patterns. No significant relationship was found between atypical sensory processing and adaptive behaviour. However, the analysis showed a strong relationship between sensory processing and maladaptive behaviour. Both maladaptive behaviour and sensory processing difficulties correlated significantly with maternal stress although maternal stress was predicted only by the sensory variable, and in particular by the avoider pattern. The findings suggest that sensory features in ASD may be driving the high prevalence of parental stress in carers. They also suggest that the effect on parental stress that has been attributed traditionally to maladaptive behaviours may be driven by sensory difficulties. The implications of these findings are discussed in relation to the development of interventions and the need to explore contextual and cultural variables as possible sources of variability. © 2017 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

Impact of self-esteem and sex on stress reactions.

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Kogler, Lydia; Seidel, Eva-Maria; Metzler, Hannah; Thaler, Hanna; Boubela, Roland N; Pruessner, Jens C; Kryspin-Exner, Ilse; Gur, Ruben C; Windischberger, Christian; Moser, Ewald; Habel, Ute; Derntl, Birgit

2017-12-08

Positive self-evaluation is a major psychological resource modulating stress coping behavior. Sex differences have been reported in self-esteem as well as stress reactions, but so far their interactions have not been investigated. Therefore, we investigated sex-specific associations of self-esteem and stress reaction on behavioral, hormonal and neural levels. We applied a commonly used fMRI-stress task in 80 healthy participants. Men compared to women showed higher activation during stress in hippocampus, precuneus, superior temporal gyrus (STG) and insula. Furthermore, men outperformed women in the stress task and had higher cortisol and testosterone levels than women after stress. Self-esteem had an impact on precuneus, insula and STG activation during stress across the whole group. During stress, men recruit regions associated with emotion and stress regulation, self-referential processing and cognitive control more strongly than women. Self-esteem affects stress processing, however in a sex-independent fashion: participants with lower self-esteem show higher activation of regions involved in emotion and stress regulation, self-referential processing and cognitive control. Taken together, our data suggest that men are more engaged during the applied stress task. Across women and men, lower self-esteem increases the effort in emotion and stress processing and cognitive control, possibly leading to self-related thoughts in stressful situations.

Acute Stress Suppresses Synaptic Inhibition and Increases Anxiety via Endocannabinoid Release in the Basolateral Amygdala.

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Di, Shi; Itoga, Christy A; Fisher, Marc O; Solomonow, Jonathan; Roltsch, Emily A; Gilpin, Nicholas W; Tasker, Jeffrey G

2016-08-10

Stress and glucocorticoids stimulate the rapid mobilization of endocannabinoids in the basolateral amygdala (BLA). Cannabinoid receptors in the BLA contribute to anxiogenesis and fear-memory formation. We tested for rapid glucocorticoid-induced endocannabinoid regulation of synaptic inhibition in the rat BLA. Glucocorticoid application to amygdala slices elicited a rapid, nonreversible suppression of spontaneous, but not evoked, GABAergic synaptic currents in BLA principal neurons; the effect was also seen with a membrane-impermeant glucocorticoid, but not with intracellular glucocorticoid application, implicating a membrane-associated glucocorticoid receptor. The glucocorticoid suppression of GABA currents was not blocked by antagonists of nuclear corticosteroid receptors, or by inhibitors of gene transcription or protein synthesis, but was blocked by inhibiting postsynaptic G-protein activity, suggesting a postsynaptic nongenomic steroid signaling mechanism that stimulates the release of a retrograde messenger. The rapid glucocorticoid-induced suppression of inhibition was prevented by blocking CB1 receptors and 2-arachidonoylglycerol (2-AG) synthesis, and it was mimicked and occluded by CB1 receptor agonists, indicating it was mediated by the retrograde release of the endocannabinoid 2-AG. The rapid glucocorticoid effect in BLA neurons in vitro was occluded by prior in vivo acute stress-induced, or prior in vitro glucocorticoid-induced, release of endocannabinoid. Acute stress also caused an increase in anxiety-like behavior that was attenuated by blocking CB1 receptor activation and inhibiting 2-AG synthesis in the BLA. Together, these findings suggest that acute stress causes a long-lasting suppression of synaptic inhibition in BLA neurons via a membrane glucocorticoid receptor-induced release of 2-AG at GABA synapses, which contributes to stress-induced anxiogenesis. We provide a cellular mechanism in the basolateral amygdala (BLA) for the rapid stress

Experimental and numerical investigation on cold flat rolling processes of DC04 sheets with special focus on residual stresses

International Nuclear Information System (INIS)

Bauer, A; Binotsch, C; Awiszus, B; Mehner, T; Sieber, M; Lampke, T

2016-01-01

The process of cold flat rolling is a widespread industrial technique to manufacture semi-finished products, e.g., for the automotive or homewares industry. Basic knowledge of the process regarding dimensioning and adjustment of defined characteristics is already state of the art. However, a detailed consideration and analysis with respect to local inhomogeneous residual stresses in several process steps mostly remains disregarded. A broad understanding of the process due to the distribution of residual stresses in the workpiece and the direction of the stress tensors allows for a definition of the characteristics of the workpiece even before the actual manufacturing process. For that purpose, it is necessary to perform numerical investigations by means of the finite element analysis (FEA) of cold flat rolling processes. Within this contribution, several approaches for the calibration of the FEA with the real flat rolling process will be addressed and discussed. To ensure that the numerical consideration provides realistic results, this calibration is indispensable. General parameters such as geometry, height reduction, rolling temperature, process time, and the rolling speed are considered as well as a photogrammetric survey, and calculated residual stresses with results of X-ray diffraction (XRD) will be compared. In the course of the experiments, a good agreement between the stress results of the FEA and the XRD was found in the center of the specimen. In combination with the allocation of the stress orientations, the agreement close to the edges is also fine. Some issues that cause differences between the FEA and the experiment are dis-cussed. (paper)

Cold stress increases reactive oxygen species formation via TRPA1 activation in A549 cells.

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Sun, Wenwu; Wang, Zhonghua; Cao, Jianping; Cui, Haiyang; Ma, Zhuang

2016-03-01

Reactive oxygen species (ROS) are responsible for lung damage during inhalation of cold air. However, the mechanism of the ROS production induced by cold stress in the lung is still unclear. In this work, we measured the changes of ROS and the cytosolic Ca(2+) concentration ([Ca(2+)]c) in A549 cell. We observed that cold stress (from 20 to 5 °C) exposure of A549 cell resulted in an increase of ROS and [Ca(2+)]c, which was completely attenuated by removing Ca(2+) from medium. Further experiments showed that cold-sensing transient receptor potential subfamily member 1 (TRPA1) agonist (allyl isothiocyanate, AITC) increased the production of ROS and the level of [Ca(2+)]c in A549 cell. Moreover, HC-030031, a TRPA1 selective antagonist, significantly inhibited the enhanced ROS and [Ca(2+)]c induced by AITC or cold stimulation, respectively. Taken together, these data demonstrated that TRPA1 activation played an important role in the enhanced production of ROS induced by cold stress in A549 cell.

Plants in water-controlled ecosystems: active role in hydrologic processes and response to water stress. III. Vegetation water stress

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Porporato, A.; Laio, F.; Ridolfi, L.; Rodriguez-Iturbe, I.

The reduction of soil moisture content during droughts lowers the plant water potential and decreases transpiration; this in turn causes a reduction of cell turgor and relative water content which brings about a sequence of damages of increasing seriousness. A review of the literature on plant physiology and water stress shows that vegetation water stress can be assumed to start at the soil moisture level corresponding to incipient stomatal closure and reach a maximum intensity at the wilting point. The mean crossing properties of these soil moisture levels crucial for water stress are derived analytically for the stochastic model of soil moisture dynamics described in Part II (F. Laio, A. Porporato, L. Ridolfi, I. Rodriguez-Iturbe. Adv. Water Res. 24 (7) (2001) 707-723). These properties are then used to propose a measure of vegetation water stress which combines the mean intensity, duration, and frequency of periods of soil water deficit. The characteristics of vegetation water stress are then studied under different climatic conditions, showing how the interplay between plant, soil, and environment can lead to optimal conditions for vegetation.

Exercise Increases Cystathionine-γ-lyase Expression and Decreases the Status of Oxidative Stress in Myocardium of Ovariectomized Rats.

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Tang, Zhiping; Wang, Yujun; Zhu, Xiaoyan; Ni, Xin; Lu, Jianqiang

2016-01-01

Exercise could be a therapeutic approach for cardiovascular dysfunction induced by estrogen deficiency. Our previous study has shown that estrogen maintains cystathionine-γ-lyase (CSE) expression and inhibits oxidative stress in the myocardium of female rats. In the present study, we investigated whether exercise improves CSE expression and oxidative stress status and ameliorates isoproterenol (ISO)-induced cardiac damage in ovariectomized (OVX) rats. The results showed that treadmill training restored the ovariectomy-induced reduction of CSE and estrogen receptor (ER)α and decrease of total antioxidant capacity (T-AOC) and increase of malondialdehyde (MDA). The level of CSE was positively correlated to T-AOC and ERα while inversely correlated to MDA. OVX rats showed increases in the serum levels of creatine kinase (CK) and lactate dehydrogenase (LDH) and the percentage of TUNEL staining in myocardium upon ISO insult compared to sham rats. Exercise training significantly reduced the serum levels of LDH and CK and the percentage of TUNEL staining in myocardium upon ISO insult in OVX rats. In cultured cardiomyocytes, ISO treatment decreased cell viability and increased LDH release, while overexpression of CSE increased cell viability and decreased LDH release in the cells upon ISO insult. The results suggest that exercise training improves the oxidative stress status and ameliorates the cardiac damage induced by oxidative stress in OVX rats. The improvement of oxidative stress status by exercise might be at least partially due to upregulation of CSE/H2S signaling.

NMDA receptor modulation by dextromethorphan and acute stress selectively alters electroencephalographic indicators of partial report processing.

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Weckesser, Lisa J; Enge, Sören; Riedel, Philipp; Kirschbaum, Clemens; Miller, Robert

2017-10-01

Proceeding from a biophysical network model, the present study hypothesized that glutamatergic neurotransmission across the NMDA receptor (NMDAR) plays a key role in visual perception and its modulation by acute stress. To investigate these hypotheses, behavioral and electroencephalographic (EEG) indicators of partial report task processing were assessed in twenty-four healthy young men who randomly received a non-competitive NMDAR antagonist (0.8 mg/kg dextromethorphan, DXM) or a placebo, and concurrently accomplished a stress-induction (MAST) or control protocol in three consecutive sessions. Saliva samples served to quantify cortisol responses to the MAST, whereas a passive auditory oddball paradigm was implemented to verify the impact of DXM on the EEG-derived mismatch negativity component (MMN). DXM administration significantly increased MMN amplitudes but not salivary cortisol concentrations. By contrast, concurrent MAST exposure significantly reduced MMN latencies but also increased cortisol concentrations. With regard to EEG indicators, DXM administration reduced visually "evoked" (30Hz to 50Hz) and "induced" occipital gamma-band activity (70Hz to 100Hz), which was partly compensated by additional MAST exposure. However, neither the interventions nor EEG activity were significantly associated with behavioral partial report sensitivities. In summary, the present data suggest that glutamatergic neurotransmission across the NMDAR is only one among many determinants of intact visual perception. Accordingly, therapeutic doses of DXM and their inhibitory modulation by stress probably yield more pronounced electroencephalographic as compared with behavioural effects. Copyright © 2017 Elsevier B.V. and ECNP. All rights reserved.

Subchronic mild noise stress increases HRP permeability in rat small intestine in vitro

NARCIS (Netherlands)

Bijlsma, P. B.; van Raaij, M. T.; Dobbe, C. J.; Timmerman, A.; Kiliaan, A. J.; Taminiau, J. A.; Groot, J. A.

2001-01-01

Recently we reported an increased trans- and paracellular protein permeability in rat small intestine after acute cold restraint stress. In the present study, we applied randomized 95- or 105-dB white noise pulses during 45 min/h, 12 h/day, duration 8 days, as a milder, but more chronic stressor to

Decreased oxidative stress may contribute to the disease process in placenta accreta

Science.gov (United States)

Öztaş, Efser; Özler, Sibel; Ergin, Merve; Erel, Özcan; Gümüş Güler, Başak; Çağlar, Ali Turhan; Yücel, Aykan; Uygur, Dilek; Danışman, Nuri

2017-08-23

Background/aim: The main aim of this study was to investigate serum total oxidant status (TOS), total antioxidant status (TAS), oxidative stress index (OSI), and arylesterase levels in pregnant women with placenta accreta and to compare those with age-matched healthy pregnant women. Materials and methods: A total of 27 pregnant women who had clinically and pathologically proven placenta accreta and 30 age- and BMI- matched healthy pregnant women were enrolled in this case control study. Maternal serum TOS, TAS, OSI, and arylesterase levels were evaluated using logistic regression analysis to determine if there was an association with abnormal placental invasion or not. Results: Decreased OSI (OR= 0.999, 95%CI: 0.998-1.000, P = 0.035) and increased arylesterase levels (OR= 0.981, 95%CI: 0.970-0.993, P = 0.001) were significantly associated with the presence of placenta accreta. Maternal serum TOS, TAS, OSI, and arylesterase levels were not predictive for adverse perinatal outcomes (P > 0.05). Conclusions: Decreased OSI and increased arylesterase levels are significantly associated with placenta accreta and may contribute to the abnormal invasion process.

Accelerated Growth Rate and Increased Drought Stress Resilience of the Model Grass Brachypodium distachyon Colonized by Bacillus subtilis B26.

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François Gagné-Bourque

Full Text Available Plant growth-promoting bacteria (PGB induce positive effects in plants, for instance, increased growth and reduced abiotic stresses susceptibility. The mechanisms by which these bacteria impact the host plant are numerous, diverse and often specific. Here, we studied the agronomical, molecular and biochemical effects of the endophytic PGB Bacillus subtilis B26 on the full life cycle of Brachypodium distachyon Bd21, an established model species for functional genomics in cereal crops and temperate grasses. Inoculation of Brachypodium with B. subtilis strain B26 increased root and shoot weights, accelerated growth rate and seed yield as compared to control plants. B. subtilis strain B26 efficiently colonized the plant and was recovered from roots, stems and blades as well as seeds of Brachypodium, indicating that the bacterium is able to migrate, spread systemically inside the plant, establish itself in the aerial plant tissues and organs, and is vertically transmitted to seeds. The presence of B. subtilis strain B26 in the seed led to systemic colonization of the next generation of Brachypodium plants. Inoculated Brachypodium seedlings and mature plants exposed to acute and chronic drought stress minimized the phenotypic effect of drought compared to plants not harbouring the bacterium. Protection from the inhibitory effects of drought by the bacterium was linked to upregulation of the drought-response genes, DREB2B-like, DHN3-like and LEA-14-A-like and modulation of the DNA methylation genes, MET1B-like, CMT3-like and DRM2-like, that regulate the process. Additionally, total soluble sugars and starch contents increased in stressed inoculated plants, a biochemical indication of drought tolerance. In conclusion, we show a single inoculation of Brachypodium with a PGB affected the whole growth cycle of the plant, accelerating its growth rates, shortening its vegetative period, and alleviating drought stress effects. These effects are relevant to

Increased resistance to a generalist herbivore in a salinity-stressed non-halophytic plant.

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Renault, Sylvie; Wolfe, Scott; Markham, John; Avila-Sakar, Germán

2016-01-01

Plants often grow under the combined stress of several factors. Salinity and herbivory, separately, can severely hinder plant growth and reproduction, but the combined effects of both factors are still not clearly understood. Salinity is known to reduce plant tissue nitrogen content and growth rates. Since herbivores prefer tissues with high N content, and biochemical pathways leading to resistance are commonly elicited by salt-stress, we hypothesized that plants growing in saline conditions would have enhanced resistance against herbivores. The non-halophyte, Brassica juncea, and the generalist herbivore Trichoplusia ni were used to test the prediction that plants subjected to salinity stress would be both more resistant and more tolerant to herbivory than those growing without salt stress. Plants were grown under different NaCl levels, and either exposed to herbivores and followed by removal of half of their leaves, or left intact. Plants were left to grow and reproduce until senescence. Tissue quality was assessed, seeds were counted and biomass of different organs measured. Plants exposed to salinity grew less, had reduced tissue nitrogen, protein and chlorophyll content, although proline levels increased. Specific leaf area, leaf water content, transpiration and root:shoot ratio remained unaffected. Plants growing under saline condition had greater constitutive resistance than unstressed plants. However, induced resistance and tolerance were not affected by salinity. These results support the hypothesis that plants growing under salt-stress are better defended against herbivores, although in B. juncea this may be mostly through resistance, and less through tolerance. Published by Oxford University Press on behalf of the Annals of Botany Company.

Flow and Stress Field Analysis of Different Fluids and Blades for Fermentation Process

OpenAIRE

Cheng-Chi Wang; Po-Jen Cheng; Kuo-Chi Liu; Ming-Yi Tsai

2014-01-01

Fermentation techniques are applied for the biotechnology and are widely used for food manufacturing, materials processing, chemical reaction, and so forth. Different fluids and types of blades in the tank for fermentation cause distinct flow and stress field distributions on the surface between fluid and blade and various flow reactions in the tank appear. This paper is mainly focused on the analysis of flow field with different fluid viscosities and also studied the stress field acting on t...

New process for the relief of mechanically induced stresses in steam generator tubes

International Nuclear Information System (INIS)

Joyeux, J.P.

1980-01-01

Heat exchangers include very generally a set of tubes assembled in 'U-type' exchangers or in 'pass-through' exchangers. The tubes are introduced in holes drilled in the tube sheet plate, welded at their extremity and expanded to insure the necessary tightness. The steam generators built by FRAMATOME belong to the U-type and include, depending upon the nominal power of the plant, about three or five thousand inconel tubes. This material has been selected for its resistance to corrosion action at high temperatures. But one drawback of inconel is that residual stress lowers considerably this resistance to corrosion; so it is very important to apply manufacturing processes involving a residual stress level as low as possible. A new process, which involves 'kiss' rolling, is described. (author)

Forced treadmill exercise can induce stress and increase neuronal damage in a mouse model of global cerebral ischemia

Directory of Open Access Journals (Sweden)

Martina Svensson

2016-12-01

Full Text Available Physical exercise is known to be a beneficial factor by increasing the cellular stress tolerance. In ischemic stroke, physical exercise is suggested to both limit the brain injury and facilitate behavioral recovery. In this study we investigated the effect of physical exercise on brain damage following global cerebral ischemia in mice. We aimed to study the effects of 4.5 weeks of forced treadmill running prior to ischemia on neuronal damage, neuroinflammation and its effect on general stress by measuring corticosterone in feces. We subjected C57bl/6 mice (n = 63 to either treadmill running or a sedentary program prior to induction of global ischemia. Anxious, depressive, and cognitive behaviors were analyzed. Stress levels were analyzed using a corticosterone ELISA. Inflammatory and neurological outcomes were analyzed using immunohistochemistry, multiplex electrochemoluminescence ELISA and Western blot. To our surprise, we found that forced treadmill running induced a stress response, with increased anxiety in the Open Field test and increased levels of corticosterone. In accordance, mice subjected to forced exercise prior to ischemia developed larger neuronal damage in the hippocampus and showed higher cytokine levels in the brain and blood compared to non-exercised mice. The extent of neuronal damage correlated with increased corticosterone levels. To compare forced treadmill with voluntary wheel running, we used a different set of mice that exercised freely on running wheels. These mice did not show any anxiety or increased corticosterone levels. Altogether, our results indicate that exercise pre-conditioning may not be beneficial if the animals are forced to run as it can induce a detrimental stress response.

Mitigation of stress corrosion cracking in pressurized water reactor (PWR) piping systems using the mechanical stress improvement process (MSIPR) or underwater laser beam welding

International Nuclear Information System (INIS)

Rick, Grendys; Marc, Piccolino; Cunthia, Pezze; Badlani, Manu

2009-01-01

A current issue facing pressurized water reactors (PWRs) is primary water stress corrosion cracking (PWSCC) of bi metallic welds. PWSCC in a PWR requires the presence of a susceptible material, an aggressive environment and a tensile stress of significant magnitude. Reducing the potential for SCC can be accomplished by eliminating any of these three elements. In the U.S., mitigation of susceptible material in the pressurizer nozzle locations has largely been completed via the structural weld overlay (SWOL) process or NuVision Engineering's Mechanical Stress Improvement Process (MSIP R) , depending on inspectability. The next most susceptible locations in Westinghouse designed power plants are the Reactor Vessel (RV) hot leg nozzle welds. However, a full SWOL Process for RV nozzles is time consuming and has a high likelihood of in process weld repairs. Therefore, Westinghouse provides two distinctive methods to mitigate susceptible material for the RV nozzle locations depending on nozzle access and utility preference. These methods are the MSIP and the Underwater Laser Beam Welding (ULBW) process. MSIP applies a load to the outside diameter of the pipe adjacent to the weld, imposing plastic strains during compression that are not reversed after unloading, thus eliminating the tensile stress component of SCC. Recently, Westinghouse and NuVision successfully applied MSIP on all eight RV nozzles at the Salem Unit 1 power plant. Another option to mitigate SCC in RV nozzles is to place a barrier between the susceptible material and the aggressive environment. The ULBW process applies a weld inlay onto the inside pipe diameter. The deposited weld metal (Alloy 52M) is resistant to PWSCC and acts as a barrier to prevent primary water from contacting the susceptible material. This paper provides information on the approval and acceptance bases for MSIP, its recent application on RV nozzles and an update on ULBW development

Increased oxidative/nitrosative stress and decreased antioxidant enzyme activities in prostate cancer.

Science.gov (United States)

Arsova-Sarafinovska, Zorica; Eken, Ayse; Matevska, Nadica; Erdem, Onur; Sayal, Ahmet; Savaser, Ayhan; Banev, Saso; Petrovski, Daniel; Dzikova, Sonja; Georgiev, Vladimir; Sikole, Aleksandar; Ozgök, Yaşar; Suturkova, Ljubica; Dimovski, Aleksandar J; Aydin, Ahmet

2009-08-01

The study was aimed to evaluate the oxidative/nitrosative stress status in prostate cancer (CaP) and benign prostatic hyperplasia (BPH). 312 men from two different populations were included: 163 men from Macedonia (73 CaP patients, 67 BPH patients and 23 control subjects) and 149 men from Turkey (34 prostate cancer patients, 100 BPH patients and 15 control subjects). We measured erythrocyte malondialdehyde (MDA) levels, erythrocyte activities of superoxide dismutase (CuZn-SOD), glutathione peroxidase (GPX) and catalase (CAT); plasma nitrite/nitrate (NO(2)(-)/NO(3)(-)), cGMP and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels. A similar pattern of alteration in the oxidative/nitrosative stress-related parameters was found in both, Macedonian and Turkish studied samples: higher MDA concentrations with lower GPX and CuZn-SOD activities in CaP patients versus controls and BPH groups. The CAT activity was decreased in the CaP patients versus controls in the Turkish studied sample. Furthermore, CaP patients had increased plasma NO(2)(-)/NO(3)(-) and cGMP levels versus controls and BPH groups in both studied samples. This study has confirmed an imbalance in the oxidative stress/antioxidant status and revealed an altered nitrosative status in prostate cancer patients.

Climatic stress increases forest fire severity across the western United States

Science.gov (United States)

van Mantgem, Philip J.; Nesmith, Jonathan C. B.; Keifer, MaryBeth; Knapp, Eric E.; Flint, Alan; Flint, Lorriane

2013-01-01

Pervasive warming can lead to chronic stress on forest trees, which may contribute to mortality resulting from fire-caused injuries. Longitudinal analyses of forest plots from across the western US show that high pre-fire climatic water deficit was related to increased post-fire tree mortality probabilities. This relationship between climate and fire was present after accounting for fire defences and injuries, and appeared to influence the effects of crown and stem injuries. Climate and fire interactions did not vary substantially across geographical regions, major genera and tree sizes. Our findings support recent physiological evidence showing that both drought and heating from fire can impair xylem conductivity. Warming trends have been linked to increasing probabilities of severe fire weather and fire spread; our results suggest that warming may also increase forest fire severity (the number of trees killed) independent of fire intensity (the amount of heat released during a fire).

Fabrication of a metallic roll stamp with low internal stress and high hardness for large area display applications by a pulse reverse current electroforming process

International Nuclear Information System (INIS)

Kim, Joongeok; Han, Jungjin; Kim, Taekyung; Kang, Shinill

2014-01-01

With the increasing demand for large scale micro/nano components in the fields of display, energy and electrical devices, etc, the establishment of a roll imprinting process has become a priority. The fabrication of a roll stamp with high dimensional accuracy and uniformity is one of the key issues in the roll imprinting process, because the roll stamp determines the properties of the replicated micro/nano structures. In this study, a method to fabricate a metallic roll stamp with low internal stress, high flatness, and high hardness was proposed by a pulse reverse current (PRC) electroforming process. The effects of PRC electroforming processes on the internal stress, hardness, and grain size of the electroformed stamp were examined, and the optimum process conditions were suggested. As a practical example of the proposed method, various micro-patterns for electronic circuits were fabricated via the roll imprinting process using a PRC electroformed stamp. (paper)

The small molecule triclabendazole decreases the intracellular level of cyclic AMP and increases resistance to stress in Saccharomyces cerevisiae.

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Yong Joo Lee

Full Text Available The Ras-adenylyl cyclase-protein kinase A nutrient-sensing pathway controls metabolism, proliferation and resistance to stress in Saccharomyces cerevisiae. The genetic disruption of this pathway increases resistance to a variety of stresses. We show here that the pharmacological inhibition of this pathway by the drug triclabendazole increases resistance to oxidants, heat stress and extends the chronological life. Evidence is presented that triclabendazole decreases the intracellular level of cyclic AMP by inhibiting adenylyl cyclase and triggers the parallel rapid translocation of the stress-resistance transcription factor Msn2 from the cytosol into the nucleus, as deduced from experiments employing a strain in which MSN2 is replaced with MSN2-GFP (GFP, green fluorescent protein. Msn2 and Msn4 are responsible for activating the transcription of numerous genes that encode proteins that protect cells from stress. The results are consistent with triclabendazole either inhibiting the association of Ras with adenylyl cyclase or directly inhibiting adenylyl cyclase, which in turn triggers Msn2/4 to enter the nucleus and activate stress-responsible element gene expression.

Process variables in organizational stress management intervention evaluation research: a systematic review

NARCIS (Netherlands)

Havermans, B.M.; Schelvis, R.M.C.; Boot, C.R.L.; Brouwers, E.P.M.; Anema, J.R.; Beek, A.J. van der

2016-01-01

Objectives This systematic review aimed to explore which process variables are used in stress management intervention (SMI) evaluation research. Methods A systematic review was conducted using seven electronic databases. Studies were included if they reported on an SMI aimed at primary or secondary

Process variables in organizational stress management intervention evaluation research : A systematic review

NARCIS (Netherlands)

Havermans, B.M.; Schlevis, Roosmarijn Mc; Boot, Cécile Rl; Brouwers, E.P.M.; Anema, Johannes R; van der Beek, Allard J

2016-01-01

OBJECTIVES: This systematic review aimed to explore which process variables are used in stress management intervention (SMI) evaluation research. METHODS: A systematic review was conducted using seven electronic databases. Studies were included if they reported on an SMI aimed at primary or

Perceived stress predicts altered reward and loss feedback processing in medial prefrontal cortex

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Michael T Treadway

2013-05-01

Full Text Available Stress is significant risk factor for the development of psychopathology, particularly symptoms related to reward processing. Importantly, individuals display marked variation in how they perceive and cope with stressful events, and such differences are strongly linked to risk for developing psychiatric symptoms following stress exposure. However, many questions remain regarding the neural architecture that underlies inter-subject variability in perceptions of stressors. Using functional magnetic resonance imaging (fMRI during a monetary incentive delay paradigm, we examined the effects of self-reported perceived stress levels on neural activity during reward anticipation and feedback in a sample of healthy individuals. We found that subjects reporting more uncontrollable and overwhelming stressors displayed blunted neural responses in medial prefrontal cortex (mPFC following feedback related to monetary gains as well monetary losses. This is consistent with preclinical models that implicate the mPFC as a key site of vulnerability to the noxious effects of uncontrollable stressors. Our data help translate these findings to humans, and elucidate some of the neural mechanisms that may underlie stress-linked risk for developing reward-related psychiatric symptoms.

The relationship between processing style, trauma memory processes, and the development of posttraumatic stress symptoms in children and adolescents.

Science.gov (United States)

McKinnon, Anna; Brewer, Neil; Cameron, Kate; Nixon, Reginald D V

2017-12-01

Data-driven processing, peri-event fear, and trauma memory characteristics are hypothesised to play a core role in the development of Posttraumatic Stress Disorder. We assessed the relationships between these characteristics and Posttraumatic Stress (PTS) symptoms in a sample of youth. Study 1 (N = 36, 7-16 years), involved a sample of children who had undergone a stressful orthopaedic procedure. One week later they answered a series of probed recall questions about the trauma (assessed for accuracy by comparison to a video) and reported on their PTS symptoms. They also rated confidence in their probed recall answers to assess meta-cognitive monitoring of their memory for the trauma. In Study 2, a sample of injured children (N = 57, 7-16 years) were assessed within 1-month of a visit to an Emergency Department, and then at 3-month follow-up. They answered probed recall questions, made confidence ratings, and completed measures of data-driven processing, peri-event fear, PTS and associated psychopathology. Memories were verified using witness accounts. Studies 1 and 2 did not find an association between PTS symptoms and trauma memory accuracy or confidence. In Studies 1 and 2 data-driven processing predicted PTS symptoms. The studies had modest samples sizes and there were ceiling effects for some accuracy and confidence items. Data-driven processing at the time of a trauma was associated with PTS symptoms after accounting for fear at the time of the trauma. Accuracy of recall for trauma memories was not significantly related to PTS symptoms. No decisive conclusion could be drawn regarding the relation between confidence in trauma memories and PTS symptoms. Copyright © 2017 Elsevier Ltd. All rights reserved.

Increased levels of thioredoxin in patients with abdominal aortic aneurysms (AAAs). A potential link of oxidative stress with AAA evolution

DEFF Research Database (Denmark)

Martinez-Pinna, R; Lindholt, Jes S.; Blanco-Colio, L M

2010-01-01

Oxidative stress is a main mechanism involved in vascular pathologies. Increased thioredoxin (TRX) levels have been observed in several oxidative stress-associated cardiovascular diseases. We aim to test the potential role of TRX as a biomarker of oxidative stress in abdominal aortic aneurysm (AAA)....

Experiments for practical education in process parameter optimization for selective laser sintering to increase workpiece quality

Science.gov (United States)

Reutterer, Bernd; Traxler, Lukas; Bayer, Natascha; Drauschke, Andreas

2016-04-01

Selective Laser Sintering (SLS) is considered as one of the most important additive manufacturing processes due to component stability and its broad range of usable materials. However the influence of the different process parameters on mechanical workpiece properties is still poorly studied, leading to the fact that further optimization is necessary to increase workpiece quality. In order to investigate the impact of various process parameters, laboratory experiments are implemented to improve the understanding of the SLS limitations and advantages on an educational level. Experiments are based on two different workstations, used to teach students the fundamentals of SLS. First of all a 50 W CO2 laser workstation is used to investigate the interaction of the laser beam with the used material in accordance with varied process parameters to analyze a single-layered test piece. Second of all the FORMIGA P110 laser sintering system from EOS is used to print different 3D test pieces in dependence on various process parameters. Finally quality attributes are tested including warpage, dimension accuracy or tensile strength. For dimension measurements and evaluation of the surface structure a telecentric lens in combination with a camera is used. A tensile test machine allows testing of the tensile strength and the interpreting of stress-strain curves. The developed laboratory experiments are suitable to teach students the influence of processing parameters. In this context they will be able to optimize the input parameters depending on the component which has to be manufactured and to increase the overall quality of the final workpiece.

The influence of punching process on residual stress and magnetic domain structure of non-oriented silicon steel

International Nuclear Information System (INIS)

Cao, Hongzhi; Hao, Linpo; Yi, Jingwen; Zhang, Xianglin; Luo, Zhonghan; Chen, Shenglin; Li, Rongfeng

2016-01-01

The main purpose of this paper is to investigate the influence of punching process on residual stress and magnetic domain structure. The residual stress in non-oriented silicon steel after punching process was measured by nanoindentation. The maximum depth was kept constant as 300 nm during nanoindentation. The material around indentation region exhibited no significant pile-up deformation. The calculation of residual stress was based on the Suresh theoretical model. Our experimental results show that residual compressive stress was generated around the sheared edge after punching. The width of residual stress affected zone by punching was around 0.4–0.5 mm. After annealing treatment, the residual stress was significantly decreased. Magnetic domain structure was observed according to the Bitter method. The un-annealed sample exhibited complicated domain patterns, and the widths of the magnetic domains varied between 3 µm and 8 µm. Most of the domain patterns of the annealed sample were 180°-domains and 90°-domains, and the widths of the domains decreased to 1–3 µm. - Highlights: • The residual stress distribution on sheared edge was measured. • The residual compressive stress was generated around the sheared edge. • The width of residual stress affected zone was about 0.4–0.5 mm. • The shape and width of the domain structure would be changed by annealing.

On the residual stress modeling of shot-peened AISI 4340 steel: finite element and response surface methods

Science.gov (United States)

Asgari, Ali; Dehestani, Pouya; Poruraminaie, Iman

2018-02-01

Shot peening is a well-known process in applying the residual stress on the surface of industrial parts. The induced residual stress improves fatigue life. In this study, the effects of shot peening parameters such as shot diameter, shot speed, friction coefficient, and the number of impacts on the applied residual stress will be evaluated. To assess these parameters effect, firstly the shot peening process has been simulated by finite element method. Then, effects of the process parameters on the residual stress have been evaluated by response surface method as a statistical approach. Finally, a strong model is presented to predict the maximum residual stress induced by shot peening process in AISI 4340 steel. Also, the optimum parameters for the maximum residual stress are achieved. The results indicate that effect of shot diameter on the induced residual stress is increased by increasing the shot speed. Also, enhancing the friction coefficient magnitude always cannot lead to increase in the residual stress.

Elucidating the iodine stress corrosion cracking (SCC) process for zircaloy tubing

International Nuclear Information System (INIS)

Nagai, M.; Shimada, S.; Nishimura, S.; Amano, K.

1984-01-01

Several experimental investigations were made to enhance understanding of the iodine stress corrosion cracking (SCC) process for Zircaloy: (1) oxide penetration process, (2) crack initiation process, and (3) crack propagation process. Concerning the effect of the oxide layer produced by conventional steam-autoclaving, no significant difference was found between results for autoclaved and as-pickled samples. Tests with 15 species of metal iodides revealed that only those metal iodides which react thermodynamically with zirconium to produce zirconium tetraiodide (ZrI 4 ) caused SCC of Zircaloy. Detailed SEM examinations were made on the SCC fracture surface of irradiated specimens. The crack propagation rate was expressed with a da/dt=C Ksup(n) type equation by combining results of tests and calculations with a finite element method. (author)

Overexpression of S-adenosyl-L-methionine synthetase increased tomato tolerance to alkali stress through polyamine metabolism.

Science.gov (United States)

Gong, Biao; Li, Xiu; VandenLangenberg, Kyle M; Wen, Dan; Sun, Shasha; Wei, Min; Li, Yan; Yang, Fengjuan; Shi, Qinghua; Wang, Xiufeng

2014-08-01

S-adenosyl-L-methionine (SAM) synthetase is the key enzyme involved in the biosynthesis of SAM, which serves as a common precursor for polyamines (PAs) and ethylene. A SAM synthetase cDNA (SlSAMS1) was introduced into the tomato genome using the Agrobacterium tumefaciens transformation method. Transgenic plants overexpressing SlSAMS1 exhibited a significant increase in tolerance to alkali stress and maintained nutrient balance, higher photosynthetic capacity and lower oxidative stress compared with WT lines. Both in vivo and in vitro experiments indicated that the function of SlSAMS1 mainly depended on the accumulation of Spd and Spm in the transgenic lines. A grafting experiment showed that rootstocks from SlSAMS1-overexpressing plants provided a stronger root system, increased PAs accumulation, essential elements absorption, and decreased Na(+) absorption in the scions under alkali stress. As a result, fruit set and yield were significantly enhanced. To our knowledge, this is the first report to provide evidence that SlSAMS1 positively regulates tomato tolerance to alkali stress and plays a major role in modulating polyamine metabolism, resulting in maintainability of nutrient and ROS balance. © 2014 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

PEG-albumin plasma expansion increases expression of MCP-1 evidencing increased circulatory wall shear stress: an experimental study.

Directory of Open Access Journals (Sweden)

C Makena Hightower

Full Text Available Treatment of blood loss with plasma expanders lowers blood viscosity, increasing cardiac output. However, increased flow velocity by conventional plasma expanders does not compensate for decreased viscosity in maintaining vessel wall shear stress (WSS, decreasing endothelial nitric oxide (NO production. A new type of plasma expander using polyethylene glycol conjugate albumin (PEG-Alb causes supra-perfusion when used in extreme hemodilution and is effective in treating hemorrhagic shock, although it is minimally viscogenic. An acute 40% hemodilution/exchange-transfusion protocol was used to compare 4% PEG-Alb to Ringer's lactate, Dextran 70 kDa and 6% Hetastarch (670 kDa in unanesthetized CD-1 mice. Serum cytokine analysis showed that PEG-Alb elevates monocyte chemotactic protein-1 (MCP-1, a member of a small inducible gene family, as well as expression of MIP-1α, and MIP-2. MCP-1 is specific to increased WSS. Given the direct link between increased WSS and production of NO, the beneficial resuscitation effects due to PEG-Alb plasma expansion appear to be due to increased WSS through increased perfusion and blood flow rather than blood viscosity.

[Relationship between occupational stress and working ability of workers in a petroleum processing enterprise in high altitude area].

Science.gov (United States)

Ma, X M; Kang, H L; Shi, C B; Li, Y; Wu, Y F; Liu, Z H; Wang, G; Lei, H Y

2017-12-20

Objective: To investigate the relationship between occupational stress and working ability of workers in a petroleum processing enterprise in a high altitude area. Methods: A total of 728 workers in a petroleum processing enterprise at an altitude of 2850 m were subjected to a survey using Occupational Stress Inventory (OSI) , Work Ability Index (WAI) Scale, Occupational Role Questionnaire (ORQ) , Personal Strain Questionnaire (PSQ) , and Personal Resource Questionnaire (PRQ) from May 2014 to August 2016. Results: Of the 728 workers, 55 (7.6%) had a poor working ability, moderate in 262 (35.9%) , and good in 411 (56.5%). There were significant differences in WAI between the workers with different types of work, sexes, ages, and working years ( P occupational stress groups ( P Occupational stress is an influencing factor for the working ability of workers in the petroleum processing enterprise in the high altitude area. Hypoxia in high altitude area may further reduce the working ability. In order to reduce occupational stress and improve work ability, it should be considered to strengthen skills training, improve the working environment, and pay attention to mental health.

Circulating biologically active oxidized phospholipids show on-going and increased oxidative stress in older male mice

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Jinbo Liu

2013-01-01

Significance: Oxidatively modified phospholipids are increased in the circulation during common, mild oxidant stresses of aging, or in male compared to female animals. Turnover of these biologically active phospholipids by rapid transport into liver and kidney is unchanged, so circulating levels reflect continuously increased production.

Stress reaction process-based hierarchical recognition algorithm for continuous intrusion events in optical fiber prewarning system

Science.gov (United States)

Qu, Hongquan; Yuan, Shijiao; Wang, Yanping; Yang, Dan

2018-04-01

To improve the recognition performance of optical fiber prewarning system (OFPS), this study proposed a hierarchical recognition algorithm (HRA). Compared with traditional methods, which employ only a complex algorithm that includes multiple extracted features and complex classifiers to increase the recognition rate with a considerable decrease in recognition speed, HRA takes advantage of the continuity of intrusion events, thereby creating a staged recognition flow inspired by stress reaction. HRA is expected to achieve high-level recognition accuracy with less time consumption. First, this work analyzed the continuity of intrusion events and then presented the algorithm based on the mechanism of stress reaction. Finally, it verified the time consumption through theoretical analysis and experiments, and the recognition accuracy was obtained through experiments. Experiment results show that the processing speed of HRA is 3.3 times faster than that of a traditional complicated algorithm and has a similar recognition rate of 98%. The study is of great significance to fast intrusion event recognition in OFPS.

A neural hypothesis for stress-induced headache.

Science.gov (United States)

Cathcart, Stuart

2009-12-01

The mechanisms by which stress contributes to CTH are not clearly understood. The commonly accepted notion of muscle hyper-reactivity to stress in CTH sufferers is not supported in the research data. We propose a neural model whereby stress acts supra-spinally to aggravate already increased pain sensitivity in CTH sufferers. Indirect support for the model comes from emerging research elucidating complex supra-spinal networks through which psychological stress may contribute to and even cause pain. Similarly, emerging research demonstrates supra-spinal pain processing abnormalities in CTH sufferers. While research with CTH sufferers offering direct support for the model is lacking at present, initial work by our group is consistent with the models predictions, particularly, that stress aggravates already increased pain sensitivity in CTH sufferers.

Effect of increased magnesium intake on plasma cholesterol, triglyceride and oxidative stress in alloxan-diabetic rats.

Science.gov (United States)

Olatunji, L A; Soladoye, A O

2007-06-01

Cardiovascular disorders are the primary causes of morbidity and mortality in patients with diabetes mellitus (DM). Agents that improve lipid profile and reduce oxidative stress have been shown to reduce the ensuing risk factors. In the present study, we investigated whether increased magnesium intake could improve hyperglycaemia, dyslipidaemia, and reduce oxidative stress in alloxan-induced diabetic rats. Male Wistar rats were divided into non-diabetic (ND), diabetic (DM) and diabetic fed on a high magnesium diet (DM-Mg) groups. Plasma concentrations of thiobarbituric acid reactive substances (TBARS) were used as markers of oxidative stress. Plasma levels of ascorbic acid, magnesium and calcium were also determined. Diabetes was induced by injecting alloxan (100 mg/kg B.W). The fasting blood glucose levels were significantly lower in the DM-Mg rats than in the DM rats. Plasma total cholesterol, triglyceride, TBARS levels were significantly higher while plasma HDL-cholesterol, HDL-cholesterol/total cholesterol ratio, ascorbic acid levels were significantly lowered in DM rats compared with the ND rats. Increased intake of magnesium significantly abrogated these alterations. There were no significant differences in the plasma levels of magnesium and calcium between the DM and ND groups. However, plasma levels of magnesium but not calcium were significantly elevated in DM-Mg rats when compared with other groups. In conclusion, these results suggest that diet rich in magnesium could exert cardioprotective effect through reduced plasma total cholesterol, triglyceride, oxidative stress and ameliorated HDL-cholesterol/total cholesterol ratio as well as increased plasma ascorbic acid and magnesium in diabetic rats.

An analytical model to predict and minimize the residual stress of laser cladding process

Science.gov (United States)

Tamanna, N.; Crouch, R.; Kabir, I. R.; Naher, S.

2018-02-01

Laser cladding is one of the advanced thermal techniques used to repair or modify the surface properties of high-value components such as tools, military and aerospace parts. Unfortunately, tensile residual stresses generate in the thermally treated area of this process. This work focuses on to investigate the key factors for the formation of tensile residual stress and how to minimize it in the clad when using dissimilar substrate and clad materials. To predict the tensile residual stress, a one-dimensional analytical model has been adopted. Four cladding materials (Al2O3, TiC, TiO2, ZrO2) on the H13 tool steel substrate and a range of preheating temperatures of the substrate, from 300 to 1200 K, have been investigated. Thermal strain and Young's modulus are found to be the key factors of formation of tensile residual stresses. Additionally, it is found that using a preheating temperature of the substrate immediately before laser cladding showed the reduction of residual stress.

Overexpression of CaDSR6 increases tolerance to drought and salt stresses in transgenic Arabidopsis plants.

Science.gov (United States)

Kim, Eun Yu; Seo, Young Sam; Park, Ki Youl; Kim, Soo Jin; Kim, Woo Taek

2014-11-15

The partial CaDSR6 (Capsicum annuum Drought Stress Responsive 6) cDNA was previously identified as a drought-induced gene in hot pepper root tissues. However, the cellular role of CaDSR6 with regard to drought stress tolerance was unknown. In this report, full-length CaDSR6 cDNA was isolated. The deduced CaDSR6 protein was composed of 234 amino acids and contained an approximately 30 amino acid-long Asp-rich domain in its central region. This Asp-rich domain was highly conserved in all plant DSR6 homologs identified and shared a sequence identity with the N-terminal regions of yeast p23(fyp) and human hTCTP, which contain Rab protein binding sites. Transgenic Arabidopsis plants overexpressing CaDSR6 (35S:CaDSR6-sGFP) were tolerant to high salinity, as identified by more vigorous root growth and higher levels of total chlorophyll than wild type plants. CaDSR6-overexpressors were also more tolerant to drought stress compared to wild type plants. The 35S:CaDSR6-sGFP leaves retained their water content and chlorophyll more efficiently than wild type leaves in response to dehydration stress. The expression of drought-induced marker genes, such as RD20, RD22, RD26, RD29A, RD29B, RAB18, KIN2, ABF3, and ABI5, was markedly increased in CaDSR6-overexpressing plants relative to wild type plants under both normal and drought conditions. These results suggest that overexpression of CaDSR6 is associated with increased levels of stress-induced genes, which, in turn, conferred a drought tolerant phenotype in transgenic Arabidopsis plants. Overall, our data suggest that CaDSR6 plays a positive role in the response to drought and salt stresses. Copyright © 2014 Elsevier B.V. All rights reserved.

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.

[Process and mechanism of plants in overcoming acid soil aluminum stress].

Science.gov (United States)

Zhao, Tian-Long; Xie, Guang-Ning; Zhang, Xiao-Xia; Qiu, Lin-Quan; Wang, Na; Zhang, Su-Zhi

2013-10-01

Aluminum (Al) stress is one of the most important factors affecting the plant growth on acid soil. Currently, global soil acidification further intensifies the Al stress. Plants can detoxify Al via the chelation of ionic Al and organic acids to store the ionic Al in vacuoles and extrude it from roots. The Al extrusion is mainly performed by the membrane-localized anion channel proteins Al(3+)-activated malate transporter (ALMT) and multi-drug and toxin extrusion (MATE). The genes encoding ABC transporter and zinc-finger protein conferred plant Al tolerance have also been found. The identification of these Al-resistant genes makes it possible to increase the Al resistance of crop plants and enhance their production by the biological methods such as gene transformation and mark-associated breeding. The key problems needed to be solved and the possible directions in the researches of plant Al stress resistance were proposed.

IL-23 Promotes Myocardial I/R Injury by Increasing the Inflammatory Responses and Oxidative Stress Reactions

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Xiaorong Hu

2016-05-01

Full Text Available Background/Aims: Inflammation and oxidative stress play an important role in myocardial ischemia and reperfusion (I/R injury. We hypothesized that IL-23, a pro-inflammatory cytokine, could promote myocardial I/R injury by increasing the inflammatory response and oxidative stress. Methods: Male Sprague-Dawley rats were randomly assigned into sham operated control (SO group, ischemia and reperfusion (I/R group, (IL-23 + I/R group and (anti-IL-23 + I/R group. At 4 h after reperfusion, the serum concentration of lactate dehydrogenase (LDH, creatine kinase (CK and the tissue MDA concentration and SOD activity were measured. The infarcte size was measured by TTC staining. Apoptosis in heart sections were measured by TUNEL staining. The expression of HMGB1 and IL-17A were detected by Western Blotting and the expression of TNF-α and IL-6 were detected by Elisa. Results: After 4 h reperfusion, compared with the I/R group, IL-23 significantly increased the infarct size, the apoptosis of cardiomyocytes and the levels of LDH and CK (all P 0.05. All these effects were abolished by anti-IL-23 administration. Conclusion: The present study suggested that IL-23 may promote myocardial I/R injury by increasing the inflammatory responses and oxidative stress reaction.

A mutation in the HFE gene is associated with altered brain iron profiles and increased oxidative stress in mice.

Science.gov (United States)

Nandar, Wint; Neely, Elizabeth B; Unger, Erica; Connor, James R

2013-06-01

Because of the increasing evidence that H63D HFE polymorphism appears in higher frequency in neurodegenerative diseases, we evaluated the neurological consequences of H63D HFE in vivo using mice that carry H67D HFE (homologous to human H63D). Although total brain iron concentration did not change significantly in the H67D mice, brain iron management proteins expressions were altered significantly. The 6-month-old H67D mice had increased HFE and H-ferritin expression. At 12 months, H67D mice had increased H- and L-ferritin but decreased transferrin expression suggesting increased iron storage and decreased iron mobilization. Increased L-ferritin positive microglia in H67D mice suggests that microglia increase iron storage to maintain brain iron homeostasis. The 6-month-old H67D mice had increased levels of GFAP, increased oxidatively modified protein levels, and increased cystine/glutamate antiporter (xCT) and hemeoxygenase-1 (HO-1) expression indicating increased metabolic and oxidative stress. By 12 months, there was no longer increased astrogliosis or oxidative stress. The decrease in oxidative stress at 12 months could be related to an adaptive response by nuclear factor E2-related factor 2 (Nrf2) that regulates antioxidant enzymes expression and is increased in the H67D mice. These findings demonstrate that the H63D HFE impacts brain iron homeostasis, and promotes an environment of oxidative stress and induction of adaptive mechanisms. These data, along with literature reports on humans with HFE mutations provide the evidence to overturn the traditional paradigm that the brain is protected from HFE mutations. The H67D knock-in mouse can be used as a model to evaluate how the H63D HFE mutation contributes to neurodegenerative diseases. Copyright © 2013 Elsevier B.V. All rights reserved.

Interoception and Stress

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André eSchulz

2015-07-01

Full Text Available Afferent neural signals are continuously transmitted from visceral organs to the brain. Interoception refers to the processing of visceral-afferent neural signals by the central nervous system, which can finally result in the conscious perception of bodily processes. Interoception can, therefore, be described as a prominent example of information processing on the ascending branch of the brain-body axis. Stress responses involve a complex neuro-behavioral cascade, which is elicited when the organism is confronted with a potentially harmful stimulus. As this stress cascade comprises a range of neural and endocrine pathways, stress can be conceptualized as a communication process on the descending branch of the brain-body axis. Interoception and stress are, therefore, associated via the bi-directional transmission of information on the brain-body axis. It could be argued that excessive and/or enduring activation (e.g. by acute or chronic stress of neural circuits, which are responsible for successful communication on the brain-body axis, induces malfunction and dysregulation of these information processes. As a consequence, interoceptive signal processing may be altered, resulting in physical symptoms contributing to the development and/or maintenance of body-related mental disorders, which are associated with stress. In the current paper, we summarize findings on psychobiological processes underlying acute and chronic stress and their interaction with interoception. While focusing on the role of the physiological stress axes (HPA axis and autonomic nervous system, psychological factors in acute and chronic stress are also discussed. We propose a feed-forward model involving stress (in particular early life or chronic stress, as well as major adverse events, the dysregulation of physiological stress axes, altered perception of bodily sensations, and the generation of physical symptoms, which may in turn facilitate stress.

Interindividual differences in stress sensitivity: basal and stress-induced cortisol levels differentially predict neural vigilance processing under stress

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Henckens, Marloes J. A. G.; Klumpers, Floris; Everaerd, Daphne; Kooijman, Sabine C.; van Wingen, Guido A.; Fernández, Guillén

2016-01-01

Stress exposure is known to precipitate psychological disorders. However, large differences exist in how individuals respond to stressful situations. A major marker for stress sensitivity is hypothalamus-pituitary-adrenal (HPA)-axis function. Here, we studied how interindividual variance in both

Gradually Increased Training Intensity Benefits Rehabilitation Outcome after Stroke by BDNF Upregulation and Stress Suppression

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Jing Sun

2014-01-01

Full Text Available Physical training is necessary for effective rehabilitation in the early poststroke period. Animal studies commonly use fixed training intensity throughout rehabilitation and without adapting it to the animals' recovered motor ability. This study investigated the correlation between training intensity and rehabilitation efficacy by using a focal ischemic stroke rat model. Eighty male Sprague-Dawley rats were induced with middle cerebral artery occlusion/reperfusion surgery. Sixty rats with successful stroke were then randomly assigned into four groups: control (CG, n=15, low intensity (LG, n=15, gradually increased intensity (GIG, n=15, and high intensity (HG, n=15. Behavioral tests were conducted daily to evaluate motor function recovery. Stress level and neural recovery were evaluated via plasma corticosterone and brain-derived neurotrophic factor (BDNF concentration, respectively. GIG rats significantly (P<0.05 recovered motor function and produced higher hippocampal BDNF (112.87 ± 25.18 ng/g. GIG and LG rats exhibited similar stress levels (540.63 ± 117.40 nM/L and 508.07 ± 161.30 nM/L, resp., which were significantly lower (P<0.05 than that (716.90 ± 156.48 nM/L of HG rats. Training with gradually increased intensity achieved better recovery with lower stress. Our observations indicate that a training protocol that includes gradually increasing training intensity should be considered in both animal and clinical studies for better stroke recovery.

Testosterone depletion increases the susceptibility of brain tissue to oxidative damage in a restraint stress mouse model.

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Son, Seung-Wan; Lee, Jin-Seok; Kim, Hyeong-Geug; Kim, Dong-Woon; Ahn, Yo-Chan; Son, Chang-Gue

2016-01-01

Among sex hormones, estrogen is particularly well known to act as neuroprotective agent. Unlike estrogen, testosterone has not been well investigated in regard to its effects on the brain, especially under psychological stress. To investigate the role of testosterone in oxidative brain injuries under psychological stress, we adapted an orchiectomy and restraint stress model. BALB/c mice were subjected to either an orchiectomy or sham operation. After allowing 15 days for recovery, mice were re-divided into four groups according to exposure of restraint stress: sham, sham plus stress, orchiectomy, and orchiectomy plus stress. Serum testosterone was undetectable in orchiectomized groups and restraint-induced stress significantly reduced testosterone levels in sham plus stress group. The serum levels of corticosterone and adrenaline were notably elevated by restraint stress, and these elevated hormones were markedly augmented by orchiectomy. Two oxidative stressors and biomarkers for lipid and protein peroxidation were significantly increased in the cerebral cortex and hippocampus by restraint stress, while the reverse pattern was observed in antioxidant enzymes. These results were supported by histopathological findings, with 4-hydroxynonenal staining for oxidative injury and Fluoro-Jade B staining showing the degenerating neurons. The aforementioned patterns of oxidative injury were accelerated by orchiectomy. These findings strongly suggest the conclusion that testosterone exerts a protective effect against oxidative brain damage, especially under stressed conditions. Unlike estrogen, the effects of testosterone on the brain have not been thoroughly investigated. In order to investigate the role of testosterone in oxidative brain injuries under psychological stress, we adapted an orchiectomy and restraint stress model. Orchiectomy markedly augmented the restraint stress-induced elevation of serum corticosterone and adrenaline levels as well as oxidative alterations

Stress Erythropoiesis Model Systems.

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Bennett, Laura F; Liao, Chang; Paulson, Robert F

2018-01-01

Bone marrow steady-state erythropoiesis maintains erythroid homeostasis throughout life. This process constantly generates new erythrocytes to replace the senescent erythrocytes that are removed by macrophages in the spleen. In contrast, anemic or hypoxic stress induces a physiological response designed to increase oxygen delivery to the tissues. Stress erythropoiesis is a key component of this response. It is best understood in mice where it is extramedullary occurring in the adult spleen and liver and in the fetal liver during development. Stress erythropoiesis utilizes progenitor cells and signals that are distinct from bone marrow steady-state erythropoiesis. Because of that observation many genes may play a role in stress erythropoiesis despite having no effect on steady-state erythropoiesis. In this chapter, we will discuss in vivo and in vitro techniques to study stress erythropoiesis in mice and how the in vitro culture system can be extended to study human stress erythropoiesis.

Voluntary exercise and increased food intake after mild chronic stress improve social avoidance behavior in mice.

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Otsuka, Airi; Shiuchi, Tetsuya; Chikahisa, Sachiko; Shimizu, Noriyuki; Séi, Hiroyoshi

2015-11-01

It is well-established that exercise can influence psychological conditions, cognitive function, and energy metabolism in peripheral tissues including the skeletal muscle. However, it is not clear whether exercise can influence social interaction with others and alleviate defeat stress. This study investigated the effect of voluntary wheel running on impaired social interaction induced by chronic social defeat stress (SDS) using the resident-intruder social defeat model. Mice were divided into three groups: control, stress alone, and stress+exercise. SDS was performed by exposing C57BL/6 mice to retired ICR mice for 2.5 min. The C57BL/6 mice were continuously defeated by these resident (aggressor) mice and, following 5 days of SDS, experienced 2 days of rest with no SDS. Mice in the stress+exercise group were allowed to voluntarily run on a wheel for 2h after every SDS exposure. Two weeks later, compared to the control group, the stress group showed a higher ratio of time spent in the corner zone of a social interaction paradigm even though SDS did not elicit depressive- and anxiety-like behaviors. We also observed that voluntary exercise, which did not affect muscle weight and gene expression, decreased social avoidance behavior of stressed mice without clear changes in brain monoamine levels. Interestingly, food intake in the stress+exercise group was the greatest among the three groups. To test the effect of the exercise-induced increase in food intake on social behavior, we set up a pair-fed group where food intake was restricted. We then compared these mice to mice in the stress alone group. We found that the ratio of time spent in the corner zone of the social interaction test was not different between ad libitum- and pair-fed groups, although pair-fed mice spent more time in the corner zone when an aggressor mouse was present than when it was absent. In addition, pair-feeding did not show exercise-induced reductions of adrenal gland weight and enhanced the

Intensive skills week for military medical students increases technical proficiency, confidence, and skills to minimize negative stress.

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Mueller, Genevieve; Hunt, Bonnie; Wall, Van; Rush, Robert; Molof, Alan; Schoeff, Jonathan; Wedmore, Ian; Schmid, James; Laporta, Anthony

2012-01-01

The effects of stress induced cortisol on learning and memory is well documented in the literature.1-3 Memory and learning are enhanced at low levels while high levels are detrimental. Repetitive training in stressful situations enables management of the stress response4 as demonstrated by the high intensity training military members undergo to prepare for tactical situations. Appropriate management of one?s stress response is critical in the medical field, as the negative effects of stress can potentially hinder life-saving procedures and treatments. This also applies to physicians-in-training as they learn and practice triage, emergency medicine, and surgical skills prior to graduation. Rocky Vista University?s Military Medicine Honor?s Track (MMHT) held a week long high-intensity emergency medicine and surgical Intensive Skills Week (ISW), facilitated by military and university physicians, to advance students? skills and maximize training using the Human Worn Partial Surgical Task Simulator (Cut Suit). The short-term goal of the ISW was to overcome negative stress responses to increase confidence, technical and non-technical knowledge, and skill in surgery and emergency medicine in an effort to improve performance as third-year medical students. The long-term goal was to enhance performance and proficiency in residency and future medical practice. The metrics for the short-term goals were the focus of this pilot study. Results show an increase in confidence and decrease in perceived stress as well as statistically significant improvements in technical and non-technical skills and surgical instrumentation knowledge throughout the week. There is a correlative benefit to physician and non-physician military personnel, especially Special Operations Forces (SOF) medical personnel, from developing and implementing similar training programs when live tissue or cadaver models are unavailable or unfeasible. 2012.

Characterisation of random Gaussian and non-Gaussian stress processes in terms of extreme responses

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Colin Bruno

2015-01-01

Full Text Available In the field of military land vehicles, random vibration processes generated by all-terrain wheeled vehicles in motion are not classical stochastic processes with a stationary and Gaussian nature. Non-stationarity of processes induced by the variability of the vehicle speed does not form a major difficulty because the designer can have good control over the vehicle speed by characterising the histogram of instantaneous speed of the vehicle during an operational situation. Beyond this non-stationarity problem, the hard point clearly lies in the fact that the random processes are not Gaussian and are generated mainly by the non-linear behaviour of the undercarriage and the strong occurrence of shocks generated by roughness of the terrain. This non-Gaussian nature is expressed particularly by very high flattening levels that can affect the design of structures under extreme stresses conventionally acquired by spectral approaches, inherent to Gaussian processes and based essentially on spectral moments of stress processes. Due to these technical considerations, techniques for characterisation of random excitation processes generated by this type of carrier need to be changed, by proposing innovative characterisation methods based on time domain approaches as described in the body of the text rather than spectral domain approaches.

A novel design for storage of inner stress by colloidal processing on rock-like materials

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Chen, Weichang; Wang, Sijing; Lekan Olatayo, Afolagboye; Fu, Huanran

2018-06-01

Inner stress exists in rocks, affecting rock engineering, yet has received very little attention and quantitative investigation because of uncertainty about its characteristics. Previous studies have suggested that the inner stresses of rock materials are closely related to their physical state variation. In this work, a novel mold was designed to simulate the storage process of inner stress in specimens composed of quartz sands and epoxy. Then, thermal tests were carried out to change the physical state of the specimens, and expansion of the specimens was monitored. The results indicated that inner stress could be partly locked by the mold and it could also be released by heating. It can be inferred from the analysis that one necessary condition of storage and release of inner stress is physical state variation. Additionally, by using an XRD method, the variations in the interplanar spacing of the quartz sands were detected, and the results reflect that inner stress could be locked-in aggregates (quartz sands) by a cement constraint (solid epoxy). The inner stress stored in quartz sands was calculated using height and interplanar spacing variations.

Mechanical wounding induces a nitrosative stress by down-regulation of GSNO reductase and an increase in S-nitrosothiols in sunflower (Helianthus annuus) seedlings

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Chaki, Mounira; Valderrama, Raquel; Fernández-Ocaña, Ana M.; Carreras, Alfonso; Gómez-Rodríguez, Maria. V.; Pedrajas, José R.; Begara-Morales, Juan C.; Sánchez-Calvo, Beatriz; Luque, Francisco; Leterrier, Marina; Corpas, Francisco J.; Barroso, Juan B.

2011-01-01

Nitric oxide (NO) and related molecules such as peroxynitrite, S-nitrosoglutathione (GSNO), and nitrotyrosine, among others, are involved in physiological processes as well in the mechanisms of response to stress conditions. In sunflower seedlings exposed to five different adverse environmental conditions (low temperature, mechanical wounding, high light intensity, continuous light, and continuous darkness), key components of the metabolism of reactive nitrogen species (RNS) and reactive oxygen species (ROS), including the enzyme activities L-arginine-dependent nitric oxide synthase (NOS), S-nitrosogluthathione reductase (GSNOR), nitrate reductase (NR), catalase, and superoxide dismutase, the content of lipid hydroperoxide, hydrogen peroxide, S-nitrosothiols (SNOs), the cellular level of NO, GSNO, and GSNOR, and protein tyrosine nitration [nitrotyrosine (NO2-Tyr)] were analysed. Among the stress conditions studied, mechanical wounding was the only one that caused a down-regulation of NOS and GSNOR activities, which in turn provoked an accumulation of SNOs. The analyses of the cellular content of NO, GSNO, GSNOR, and NO2-Tyr by confocal laser scanning microscopy confirmed these biochemical data. Therefore, it is proposed that mechanical wounding triggers the accumulation of SNOs, specifically GSNO, due to a down-regulation of GSNOR activity, while NO2-Tyr increases. Consequently a process of nitrosative stress is induced in sunflower seedlings and SNOs constitute a new wound signal in plants. PMID:21172815

Transformation-Induced Relaxation and Stress Recovery of TiNi Shape Memory Alloy

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Kohei Takeda

2014-03-01

Full Text Available The transformation-induced stress relaxation and stress recovery of TiNi shape memory alloy (SMA in stress-controlled subloop loading were investigated based on the local variation in temperature and transformation band on the surface of the tape in the tension test. The results obtained are summarized as follows. (1 In the loading process, temperature increases due to the exothermic martensitic transformation (MT until the holding strain and thereafter temperature decreases while holding the strain constant, resulting in stress relaxation due to the MT; (2 In the unloading process, temperature decreases due to the endothermic reverse transformation until the holding strain and thereafter temperature increases while holding the strain constant, resulting in stress recovery due to the reverse transformation; (3 Stress varies markedly in the initial stage followed by gradual change while holding the strain constant; (4 If the stress rate is high until the holding strain in the loading and unloading processes, both stress relaxation and stress recovery are large; (5 It is important to take into account this behavior in the design of SMA elements, since the force of SMA elements varies even if the atmospheric temperature is kept constant.

Overexpressing the Sedum alfredii Cu/Zn Superoxide Dismutase Increased Resistance to Oxidative Stress in Transgenic Arabidopsis

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Zhen Li

2017-06-01

Full Text Available Superoxide dismutase (SOD is a very important reactive oxygen species (ROS-scavenging enzyme. In this study, the functions of a Cu/Zn SOD gene (SaCu/Zn SOD, from Sedum alfredii, a cadmium (Cd/zinc/lead co-hyperaccumulator of the Crassulaceae, was characterized. The expression of SaCu/Zn SOD was induced by Cd stress. Compared with wild-type (WT plants, overexpression of SaCu/Zn SOD gene in transgenic Arabidopsis plants enhanced the antioxidative defense capacity, including SOD and peroxidase activities. Additionally, it reduced the damage associated with the overproduction of hydrogen peroxide (H2O2 and superoxide radicals (O2•-. The influence of Cd stress on ion flux across the root surface showed that overexpressing SaCu/Zn SOD in transgenic Arabidopsis plants has greater Cd uptake capacity existed in roots. A co-expression network based on microarray data showed possible oxidative regulation in Arabidopsis after Cd-induced oxidative stress, suggesting that SaCu/Zn SOD may participate in this network and enhance ROS-scavenging capability under Cd stress. Taken together, these results suggest that overexpressing SaCu/Zn SOD increased oxidative stress resistance in transgenic Arabidopsis and provide useful information for understanding the role of SaCu/Zn SOD in response to abiotic stress.

Chronic restraint stress in rats causes sustained increase in urinary corticosterone excretion without affecting cerebral or systemic oxidatively generated DNA/RNA damage

DEFF Research Database (Denmark)

Jorgensen, Anders; Maigaard, Katrine; Wörtwein, Gitta

2013-01-01

acids, 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo), respectively, in rats subjected to chronic restraint stress. To reliably collect 24h urine samples, the full 3-week restraint stress paradigm was performed in metabolism cages. We further determined frontal...... and Tnf). The metabolism cage housing in itself did not significantly influence a range of biological stress markers. In the restraint stress group, there was a sustained 2.5 fold increase in 24h corticosterone excretion from day 2 after stress initiation. However, neither whole-body nor cerebral measures......Increased oxidatively generated damage to nucleic acids (DNA/RNA) may be a common mechanism underlying accelerated aging in psychological stress states and mental disorders. In the present study, we measured the urinary excretion of corticosterone and markers of systemic oxidative stress on nucleic...

Effect of acute heat stress and slaughter processing on poultry meat quality and postmortem carbohydrate metabolism.

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Wang, R H; Liang, R R; Lin, H; Zhu, L X; Zhang, Y M; Mao, Y W; Dong, P C; Niu, L B; Zhang, M H; Luo, X

2017-03-01

This study investigated the effects of acute heat stress and slaughter processing on poultry meat quality and carbohydrate metabolism. Broilers (200) were randomly divided into 2 groups receiving heat stress (HS; 36°C for one h), compared to a non-stressed control (C). At slaughter, each group was further divided into 2 groups for slaughter processing (L = laboratory; F = commercial factory). L group breasts were removed immediately after bleeding without carcass scalding or defeathering, and stored at 4°C. F group broilers were scalded (60°C, 45 s) after bleeding and defeathering. Then the breasts were removed and cooled in ice water until the core temperature was ≤4°C. Rates of Pectoralis core temperature and pH decline were changed by slaughter processing, but only HS affected ultimate pH in group L. HS muscles had higher L* values (P  0.05). Sarcoplasmic protein solubility was higher in F processed birds (P < 0.05). HS decreased the solubility of myofibrillar and total protein in the L-slaughtered birds. Thus, HS caused a higher frequency of accelerated muscle glycolysis than controls. Factory processing (chilling) could not completely eliminate the effects of accelerated glycolysis caused by pre-slaughter HS. © 2016 Poultry Science Association Inc.

Exposure to high hydrostatic pressure rapidly selects for increased RpoS activity and general stress-resistance in Escherichia coli O157:H7.

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Vanlint, Dietrich; Rutten, Nele; Govers, Sander K; Michiels, Chris W; Aertsen, Abram

2013-04-15

Exposure to high hydrostatic pressure (HHP) is increasingly being used in food preservation as a non-thermal pasteurization process, and its further implementation necessitates a more thorough understanding of bacterial resistance development and intraspecies variability with regard to inactivation by HHP. In this report, we discovered that exposure to high hydrostatic pressure stress can rapidly select for strongly increased RpoS activity in a hypersensitive Escherichia coli O157:H7 strain (ATCC 43888), leading to a simultaneous increase in HHP and heat resistance. Moreover, the level of RpoS activity correlated well with the original hypersensitivity and the extent of acquired HHP resistance, and extremely HHP-resistant mutants of ATCC 43888 clearly incurred a number of additional RpoS-dependent phenotypes. These findings suggest that implementation of novel processing techniques in the food production chain can readily affect the physiology of food-borne pathogens. Copyright © 2013 Elsevier B.V. All rights reserved.

Exogenous Cytokinins Increase Grain Yield of Winter Wheat Cultivars by Improving Stay-Green Characteristics under Heat Stress.

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Dongqing Yang

Full Text Available Stay-green, a key trait of wheat, can not only increase the yield of wheat but also its resistance to heat stress during active photosynthesis. Cytokinins are the most potent general coordinator between the stay-green trait and senescence. The objectives of the present study were to identify and assess the effects of cytokinins on the photosynthetic organ and heat resistance in wheat. Two winter wheat cultivars, Wennong 6 (a stay-green cultivar and Jimai 20 (a control cultivar, were subjected to heat stress treatment from 1 to 5 days after anthesis (DAA. The two cultivars were sprayed daily with 10 mg L-1 of 6-benzylaminopurine (6-BA between 1 and 3 DAA under ambient and elevated temperature conditions. We found that the heat stress significantly decreased the number of kernels per spike and the grain yield (P < 0.05. Heat stress also decreased the zeatin riboside (ZR content, but increased the gibberellin (GA3, indole-3-acetic acid (IAA, and abscisic acid (ABA contents at 3 to 15 DAA. Application of 6-BA significantly (P < 0.05 increased the grain-filling rate, endosperm cell division rate, endosperm cell number, and 1,000-grain weight under heated condition. 6-BA application increased ZR and IAA contents at 3 to 28 DAA, but decreased GA3 and ABA contents. The contents of ZR, ABA, and IAA in kernels were positively and significantly correlated with the grain-filling rate (P < 0.05, whereas GA3 was counter-productive at 3 to 15 DAA. These results suggest that the decrease in grain yield under heat stress was due to a lower ZR content and a higher GA3 content compared to that at elevated temperature during the early development of the kernels, which resulted in less kernel number and lower grain-filling rate. The results also provide essential information for further utilization of the cytokinin substances in the cultivation of heat-resistant wheat.

The effect of air velocity on heat stress at increased air temperature

DEFF Research Database (Denmark)

Bjerg, B.; Wang, Xiaoshuai; Zhang, Guoqiang

Increased air velocity is a frequently used method to reduce heat stress of farm animals housed in warm conditions. The main reason why the method works is that higher air velocity increases the convective heat release from the animals. Convective heat release from the animals is strongly related...... to the temperature difference between the surfaces of animals and the surrounding air, and this temperature difference declines when the air temperature approaches the animal body temperature. Consequently it can it by expected that the effect of air velocity decreases at increased air temperature. The literature...... on farm animals in warm conditions includes several thermal indices which incorporate the effect of air velocities. But, surprisingly none of them predicts a decreased influence of air velocity when the air temperature approaches the animal body temperature. This study reviewed published investigations...

Stress-related increases in risk taking and attentional failures predict earlier relapse to smoking in young adults: A pilot investigation.

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Schepis, Ty S; Tapscott, Brian E; Krishnan-Sarin, Suchitra

2016-04-01

Substantial evidence links greater impulsivity and stress exposure to poorer smoking cessation outcomes. Results from adolescents also indicate that stress-related change in risk taking can impede cessation attempts. We investigated the effects of stress-related change in impulsivity, risk taking, attention and nicotine withdrawal, and craving in young adult smokers on time to smoking relapse in a relapse analogue paradigm. Twenty-six young adult smokers (50% women; mean age: 20.9 ± 1.8) were exposed to a stress imagery session followed by a contingency management-based relapse analogue paradigm. Participants smoked at least 5 cigarettes daily, with a mean baseline carbon monoxide (CO) level of 13.7 (± 5.1) ppm. Repeated measures analysis of variance (ANOVA) and paired t tests examined stress induction validity and Cox regressions of proportional hazards examined the effects of stress-related changes in nicotine withdrawal, nicotine craving, attention, impulsivity, and risk taking on time to relapse. While stress-related change in impulsivity, nicotine craving and withdrawal did not predict time to relapse (all ps > .10), greater stress-related increases in reaction time (RT) variability (p = .02) were predictive of shorter time to relapse, with trend-level findings for inattention and risk taking. Furthermore, changes in stress-related risk taking affected outcome in women more than in men, with a significant relationship between stress-related change in risk taking only in women (p = .026). Smoking cessation attempts in young adults may be adversely impacted by stress-related increases in risk taking and attentional disruption. Clinicians working with young adults attempting cessation may need to target these stress-related impairments by fostering more adaptive coping and resilience. (c) 2016 APA, all rights reserved).

Increased risk of coronary heart disease among individuals reporting adverse impact of stress on their health: the Whitehall II prospective cohort study.

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Nabi, Hermann; Kivimäki, Mika; Batty, G David; Shipley, Martin J; Britton, Annie; Brunner, Eric J; Vahtera, Jussi; Lemogne, Cédric; Elbaz, Alexis; Singh-Manoux, Archana

2013-09-01

Response to stress can vary greatly between individuals. However, it remains unknown whether perceived impact of stress on health is associated with adverse health outcomes. We examined whether individuals who report that stress adversely affects their health are at increased risk of coronary heart disease (CHD) compared with those who report that stress has no adverse health impact. Analyses are based on 7268 men and women (mean age: 49.5 years, interquartile range: 11 years) from the British Whitehall II cohort study. Over 18 years of follow-up, there were 352 coronary deaths or first non-fatal myocardial infarction (MI) events. After adjustment for sociodemographic characteristics, participants who reported at baseline that stress has affected their health 'a lot or extremely' had a 2.12 times higher (95% CI 1.52-2.98) risk of coronary death or incident non-fatal MI when compared with those who reported no effect of stress on their health. This association was attenuated but remained statistically significant after adjustment for biological, behavioural, and other psychological risk factors including perceived stress levels, and measures of social support; fully adjusted hazard ratio: 1.49 (95% CI 1.01-2.22). In this prospective cohort study, the perception that stress affects health, different from perceived stress levels, was associated with an increased risk of coronary heart disease. Randomized controlled trials are needed to determine whether disease risk can be reduced by increasing clinical attention to those who complain that stress greatly affects their health.

Early Life Stress Increases Metabolic Risk, HPA Axis Reactivity, and Depressive-Like Behavior When Combined with Postweaning Social Isolation in Rats.

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Vargas, Javier; Junco, Mariana; Gomez, Carlos; Lajud, Naima

2016-01-01

Early-life stress is associated with depression and metabolic abnormalities that increase the risk of cardiovascular disease and diabetes. Such associations could be due to increased glucocorticoid levels. Periodic maternal separation in the neonate and rearing in social isolation are potent stressors that increase hypothalamus-pituitary-adrenal axis activity. Moreover, social isolation promotes feed intake and body weight gain in rats subjected to periodic maternal separation; however, its effects on metabolic risks have not been described. In the present study, we evaluated whether periodic maternal separation, social isolation rearing, and a combination of these two stressors (periodic maternal separation + social isolation rearing) impair glucose homeostasis and its relation to the hypothalamus-pituitary-adrenal axis and depressive-like behavior. Periodic maternal separation increased basal corticosterone levels, induced a passive coping strategy in the forced swimming test, and was associated with a mild (24%) increase in fasting glucose, insulin resistance, and dyslipidemia. Rearing in social isolation increased stress reactivity in comparison to both controls and in combination with periodic maternal separation, without affecting the coping strategy associated with the forced swimming test. However, social isolation also increased body weight gain, fasting glucose (120%), and insulin levels in rats subjected to periodic maternal separation. Correlation analyses showed that stress-induced effects on coping strategy on the forced swimming test (but not on metabolic risk markers) are associated with basal corticosterone levels. These findings suggest that maternal separation and postweaning social isolation affect stress and metabolic vulnerability differentially and that early-life stress-related effects on metabolism are not directly dependent on glucocorticoid levels. In conclusion, our study supports the cumulative stress hypothesis, which suggests that

History of cervical insufficiency increases the risk of pelvic organ prolapse and stress urinary incontinence in parous women.

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Sheyn, David; Addae-Konaedu, Kateena L; Bauer, Alison M; Dawodu, Konyinsola I; Hackney, David N; El-Nashar, Sherif A

2018-01-01

A likely contributor to pelvic floor disorders is injury and degradation of connective tissue components such as collagen and elastin, leading to weakening of the pelvic floor. Prior studies have found similar connective tissue component changes in women with cervical insufficiency (CI). However, the connection between pelvic floor disorders and cervical insufficiency has not previously been evaluated. Our objective was to determine whether a history of cervical insufficiency is associated with an increased risk of pelvic organ prolapse and stress urinary incontinence after controlling for confounders. The study used de-identified clinical data from a large multi-institution electronic health records HIPAA-compliant data web application, Explorys Inc. (Cleveland, Ohio, USA). Women with a history of at least one prior delivery after at least 20 weeks' gestation between the years 1999 and 2016 were identified. Logistic regression models were used to identify risk factors and adjust for confounders. The primary outcome was subsequent development of either stress incontinence or pelvic organ prolapse. A total of 1,182,650 women were identified, of whom 30,890 (2.6%) had a history of cervical cerclage or insufficiency. A history of cervical insufficiency was associated with an increased risk of either pelvic organ prolapse or stress urinary incontinence (aOR=1.93, 95%CI: 1.84-2.02). A history of cervical insufficiency was more strongly associated with an increased risk of pelvic organ prolapse (aOR=2.06, 95%CI: 1.91-2.21) than with stress urinary incontinence (aOR=1.91, 95%CI: 1.80-2.02). A history of cervical insufficiency is associated with an increased risk of development of pelvic organ prolapse and stress urinary incontinence. Copyright © 2017 Elsevier B.V. All rights reserved.