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Sample records for amoeba osmotic shock

  1. Compression and Reswelling of Microgel Particles after an Osmotic Shock

    Science.gov (United States)

    Sleeboom, Jelle J. F.; Voudouris, Panayiotis; Punter, Melle T. J. J. M.; Aangenendt, Frank J.; Florea, Daniel; van der Schoot, Paul; Wyss, Hans M.

    2017-09-01

    We use dedicated microfluidic devices to expose soft hydrogel particles to a rapid change in the externally applied osmotic pressure and observe a surprising, nonmonotonic response: After an initial rapid compression, the particle slowly reswells to approximately its original size. We theoretically account for this behavior, enabling us to extract important material properties from a single microfluidic experiment, including the compressive modulus, the gel permeability, and the diffusivity of the osmolyte inside the gel. We expect our approach to be relevant to applications such as controlled release, chromatography, and responsive materials.

  2. Improvement of lipid yield from microalgae Spirulina platensis using ultrasound assisted osmotic shock extraction method

    Science.gov (United States)

    Adetya, NP; Hadiyanto, H.

    2018-01-01

    Microalgae Spirulina sp. has been identified as potential source of natural food supplement and food colorant. The high water content of microalgae (70-90%) causes an obstacle in biomass dehydration which requires large amounts of energy, eventually damaging the lipid in the microalgae. Therefore, the lipid must be extracted by using a suitable method which complies to wet biomass conditions. One of the methods is applying osmotic shock. This study was aimed to investigate the influence of osmotic agent (NaCl) concentration (10-30%) and extraction time (20-50 min) on yield of lipid and also to determine the optimal conditions in the extraction process through response surface methodology. The extraction was conducted at a temperature of 40°C under ultrasound frequency of 40 kHz. The result showed that the optimum yield lipid obtained was 6.39% in 16.98% NaCl concentration for 36 minutes 10 seconds.

  3. The effect of an extracellular mucilage on the response to osmotic shock in the charophyte alga Lamprothamnium papulosum.

    Science.gov (United States)

    Shepherd, V A; Beilby, M J

    1999-08-01

    We have used current/voltage (I/V) analysis to investigate the role played by extracellular mucilage in the cellular response to osmotic shock in Lamprothamnium papulosum. Cells lacking extracellular mucilage originated in a brackish environment (1/3 seawater). These were compared, first with cells coated with thick (approximately 50 micron) extracellular mucilage, collected from a marine lake, and second, with equivalent mucilaginous marine cells, treated with heparinase enzyme to disrupt the mucilage layer. Histochemical stains Toluidine Blue and Alcian Blue at low pH identified the major component of the extracellular mucilage as sulfated polysaccharides. Treating mucilage with heparinase removed the capacity for staining with cationic dyes at low pH, although the mucilage was not removed, and remained as a substantial unstirred layer. Cells lacking mucilage responded to hypotonic shock with depolarization (by approximately 95 mV), cessation of cyclosis, due to transient opening of Ca2+ channels, and opening of Ca2+-activated Cl- channels and K+ channels. Cell conductance transiently increased tenfold, but after 60 min was restored to the conductance prior to hypotonic shock. Mucilaginous cells depolarized by a small amount (approximately 18 mV), but Ca2+ channels failed to open in large enough numbers for cyclosis to cease. Likewise most Ca2+-activated Cl- channels failed to open and conductance increased only approximately 1.2-fold above the prehypotonic level. After 60 min conductance was less than the conductance prior to hypotonic shock. Heparinased mucilaginous cells recovered several aspects of the hypotonic response in cells lacking mucilage. These cells depolarized (by approximately 103 mV); cyclosis ceased, indicating that Ca2+ channels had opened, and conductance increased to approximately 4 times the value prior to hypotonic shock, indicating that Ca2+-activated Cl- channels opened. However, after 60 min, these cells had neither restored membrane

  4. Polyamines and plant stress - Activation of putrescine biosynthesis by osmotic shock

    Science.gov (United States)

    Flores, H. E.; Galston, A. W.

    1982-01-01

    The putrescine content of oat leaf cells and protoplasts increases up to 60-fold within 6 hours of exposure to osmotic stress (0.4 to 0.6 molar sorbitol). Barley, corn, wheat, and wild oat leaves show a similar response. Increased arginine decarboxylase activity parallels the rise in putrescine, whereas ornithine decarboxylase remains unchanged. DL-alpha-Difluoromethylarginine, a specific irreversible inhibitor of arginine decarboxylase, prevents the stress-induced rise in increase in arginine decarboxylase activity and putrescine synthesis, indicating the preferential activation of this pathway.

  5. Vitamin D protects keratinocytes from apoptosis induced by osmotic shock, oxidative stress, and tumor necrosis factor.

    Science.gov (United States)

    Diker-Cohen, Talia; Koren, Ruth; Liberman, Uri A; Ravid, Amiram

    2003-12-01

    Calcitriol, the hormonal form of vitamin D, inhibited caspase-3-like activation in HaCaT keratinocytes exposed to hyperosmotic and oxidative stresses, heat shock, and the inflammatory cytokine TNF. The hormone also protected the cells from caspase-independent cell death induced by hyperosmotic and oxidative stresses. The protection against hyperosmotic stress is not affected by inhibitors of the EGF receptor, ERK or PI13 kinase pathways, neither is it due to reduced activity of the proapoptotic p38 MAP kinase. These results are in accordance with previous in vivo findings that vitamin D protects epidermal keratinocytes from apoptosis due to UV radiation or chemotherapy.

  6. Cloning and over expression of non-coding RNA rprA in E.coli and its resistance to Kanamycin without osmotic shock.

    Science.gov (United States)

    Sahni, Azita; Hajjari, Mohammadreza; Raheb, Jamshid; Foroughmand, Ali Mohammad; Asgari, Morteza

    2017-01-01

    Recent reports have indicated that small RNAs have key roles in the response of the E.coli to stress and also in the regulating of virulence factors. It seems that some small non-coding RNAs are involved in multidrug resistance. Previous studies have indicated that rprA can increase the tolerance to Kanamycin in RcsB-deficient Escherichia coli K-12 following osmotic shock. The current study aims to clone and over-express the non-coding RNA rprA in E.coli and investigate its effect on the bacterial resistance to Kanamycin without any osmotic shock. For this purpose, rprA gene was amplified by the PCR and then cloned into the PET-28a (+) vector. The recombinant plasmid was transformed into wild type E.coli BL21 (DE3). The over expression was induced by IPTG and confirmed by qRT-PCR. The resistance to the kanamycin was then measured in different times by spectrophotometry. The statistical analysis showed that the rprA can increase the resistance to Kanamycin in Ecoli K12. The interaction between rprA and rpoS was reviewed and analyzed by in silico methods. The results showed that the bacteria with over-expressed rprA were more resistant to Kanamycin. The present study is an important step to prove the role of non-coding RNA rprA in bacterial resistance. The data can be the basis for future works and can also help to develop and deliver next-generation antibiotics.

  7. Studies on alkaline band formation in Chara corallina: ameliorating effect of Ca2+ on inhibition induced by osmotic shock.

    Science.gov (United States)

    Shimmen, Teruo; Yonemura, Satoko; Negoro, Mio; Lucas, William J

    2003-09-01

    Although the decrease in cell turgor by application of sorbitol to the external medium did not inhibit the alkaline band formation in Chara corallina, recovery of normal turgor severely inhibited it. Alkaline-loading analysis suggested that the inhibition of alkaline band formation was caused by inhibition of HCO(3)(-) influx but not that of OH(-) efflux. In the presence of 10 mM CaCl(2), the capacity of alkaline band formation was maintained during osmotic treatment. Cells could not form alkaline bands, when plasmolysis was induced by application of sorbitol at a higher concentration. Addition of 10 mM CaCl(2) could ameliorate the inhibition caused by plasmolyis.

  8. Influence of heat shock and osmotic stresses on the growth and viability of Saccharomyces cerevisiae SUBSC01.

    Science.gov (United States)

    Munna, Md Sakil; Humayun, Sanjida; Noor, Rashed

    2015-08-23

    With a preceding scrutiny of bacterial cellular responses against heat shock and oxidative stresses, current research further investigated such impact on yeast cell. Present study attempted to observe the influence of high temperature (44-46 °C) on the growth and budding pattern of Saccharomyces cerevisiae SUBSC01. Effect of elevated sugar concentrations as another stress stimulant was also observed. Cell growth was measured through the estimation of the optical density at 600 nm (OD600) and by the enumeration of colony forming units on the agar plates up to 450 min. Subsequent transformation in the yeast morphology and the cellular arrangement were noticed. A delayed and lengthy lag phase was observed when yeast strain was grown at 30, 37, and 40 °C, while at 32.5 °C, optimal growth pattern was noticed. Cells were found to lose culturability completely at 46 °C whereby cells without the cytoplasmic contents were also observed under the light microscope. Thus the critical growth temperature was recorded as 45 °C which was the highest temperature at which S. cerevisiae SUBSC01 could grow. However, a complete growth retardation was observed at 45 °C with the high concentrations of dextrose (0.36 g/l) and sucrose (0.18 g/l). Notably, yeast budding was found at 44 and 45 °C up to 270 min of incubation, which was further noticed to be suppressed at 46 °C. Present study revealed that the optimal and the critical growth temperatures of S. cerevisiae SUBSC01 were 32.5 and 45 °C, respectively; and also projected on the inhibitory concentrations of sugars on yeast growth at that temperature.

  9. Visual expression analysis of the responses of the alternative oxidase gene (aox1) to heat shock, oxidative, and osmotic stresses in conidia of citric acid-producing Aspergillus niger.

    Science.gov (United States)

    Honda, Yuki; Hattori, Takasumi; Kirimura, Kohtaro

    2012-03-01

    The citric acid-producing filamentous fungus Aspergillus niger WU-2223L shows cyanide-insensitive respiration catalyzed by alternative oxidase in addition to the cytochrome pathway. Sequence analysis of the 5' flanking region of the alternative oxidase gene (aox1) revealed a potential heat shock element (HSE) and a stress response element (STRE). We have previously confirmed aox1 expression in conidia. In this study, to confirm whether the upstream region of aox1 responds to various stresses, we used a visual expression analysis system for single-cell conidia of the A. niger strain AOXEGFP-1. This strain harbored a fusion gene comprising aox1 and egfp, which encodes the enhanced green fluorescent protein (EGFP). The fluorescence intensity of EGFP increased in conidia of A. niger AOXEGFP-1 that were subjected to heat shock at 35-45 °C, oxidative stress by exposure to 5mM paraquat or 1 mM t-butylhydroperoxide, or osmotic stresses by exposure to 0.5 M KCl or 1.0 M mannitol. These results indicate that the putative HSE and STRE in the upstream region of aox1 directly or indirectly respond to heat shock, oxidative, and osmotic stresses. Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  10. Osmotic fragility test

    Science.gov (United States)

    Spherocytosis - osmotic fragility; Thalassemia - osmotic fragility ... done to detect conditions called hereditary spherocytosis and thalassemia . Hereditary spherocytosis makes red blood cells more fragile ...

  11. Raw data for the identification of SUMOylated proteins in S. cerevisiae subjected to two types of osmotic shock, using affinity purification coupled with mass spectrometry

    Directory of Open Access Journals (Sweden)

    Tharan Srikumar

    2015-03-01

    Full Text Available The small ubiquitin-related modifier (SUMO “stress response” (SSR is a poorly understood evolutionarily conserved phenomenon in which steady-state SUMO conjugate levels are dramatically increased in response to environmental stresses. Here we describe the data acquired using affinity-purification coupled with mass spectrometry to identify proteins that are SUMOylated in response to two different types of osmotic stress, 1 M sorbitol and 1 M KCl. The mass spectrometry dataset described here has been uploaded to the MassIVE repository with ID: MSV000078739, and consists of 32 raw MS files acquired in data-dependent mode on a Thermo Q-Exactive instrument. iProphet-processed MS/MS search results and associated SAINT scores are also included as a reference. These data are discussed and interpreted in “The S. cerevisiae SUMO stress response is a conjugation–deconjugation cycle that targets the transcription machinery”, by Lewicki et al. in the Journal of Proteomics, 2014 [1].

  12. Free-Living Amoebae Keratitis.

    Science.gov (United States)

    Pinna, Antonio; Porcu, Tiziana; Boscia, Francesco; Cano, Antonella; Erre, Giuseppe; Mattana, Antonella

    2017-07-01

    To describe the diagnostic and clinical features and treatment results in 43 consecutive patients with microbiologically proven free-living amoebae (FLA) keratitis. In this hospital-based, prospective case series, corneal scrapings from 43 patients with presumed amoebic keratitis were plated on nonnutrient agar. Amoebic isolates were identified morphologically and by the polymerase chain reaction. All patients with culture-proven FLA keratitis were treated with polyhexamethylene biguanide (PHMB) 0.02% eye drops. Forty-three corneal scrapings from 43 patients were found to be culture positive for FLA; 41 (95%) were from contact lens wearers and 2 (5%) were from noncontact lens wearers. Microscopic examination identified 4 Acanthamoeba spp, 24 Hartmannella spp, 12 vahlkampfiid amoebae, and 3 mixed infections with Hartmannella/vahlkampfiid amoebae. Morphological results were confirmed by the polymerase chain reaction. Patients with Acanthamoeba, Hartmannella, and vahlkampfiid keratitis had indistinguishable clinical features. In 38 eyes with keratitis at an early stage, treatment with PHMB 0.02% eye drops was fully successful. In 5 patients with advanced keratitis, topical PHMB 0.02% controlled the infection, but all of them developed a central corneal scar with visual deterioration. Acanthamoeba is not the only cause of amoebic keratitis, because this condition may also be caused by other FLA, such as Hartmannella and vahlkampfiid amoebae. This finding is epidemiologically interesting, suggesting a possible different geographical prevalence of the different FLA responsible for keratitis. Early diagnosis and proper antiamoebic treatment are crucial to yielding a cure.

  13. Osmotic and Heat Stress Effects on Segmentation.

    Science.gov (United States)

    Weiss, Julian; Devoto, Stephen H

    2016-01-01

    During vertebrate embryonic development, early skin, muscle, and bone progenitor populations organize into segments known as somites. Defects in this conserved process of segmentation lead to skeletal and muscular deformities, such as congenital scoliosis, a curvature of the spine caused by vertebral defects. Environmental stresses such as hypoxia or heat shock produce segmentation defects, and significantly increase the penetrance and severity of vertebral defects in genetically susceptible individuals. Here we show that a brief exposure to a high osmolarity solution causes reproducible segmentation defects in developing zebrafish (Danio rerio) embryos. Both osmotic shock and heat shock produce border defects in a dose-dependent manner, with an increase in both frequency and severity of defects. We also show that osmotic treatment has a delayed effect on somite development, similar to that observed in heat shocked embryos. Our results establish osmotic shock as an alternate experimental model for stress, affecting segmentation in a manner comparable to other known environmental stressors. The similar effects of these two distinct environmental stressors support a model in which a variety of cellular stresses act through a related response pathway that leads to disturbances in the segmentation process.

  14. Osmotic and Heat Stress Effects on Segmentation.

    Directory of Open Access Journals (Sweden)

    Julian Weiss

    Full Text Available During vertebrate embryonic development, early skin, muscle, and bone progenitor populations organize into segments known as somites. Defects in this conserved process of segmentation lead to skeletal and muscular deformities, such as congenital scoliosis, a curvature of the spine caused by vertebral defects. Environmental stresses such as hypoxia or heat shock produce segmentation defects, and significantly increase the penetrance and severity of vertebral defects in genetically susceptible individuals. Here we show that a brief exposure to a high osmolarity solution causes reproducible segmentation defects in developing zebrafish (Danio rerio embryos. Both osmotic shock and heat shock produce border defects in a dose-dependent manner, with an increase in both frequency and severity of defects. We also show that osmotic treatment has a delayed effect on somite development, similar to that observed in heat shocked embryos. Our results establish osmotic shock as an alternate experimental model for stress, affecting segmentation in a manner comparable to other known environmental stressors. The similar effects of these two distinct environmental stressors support a model in which a variety of cellular stresses act through a related response pathway that leads to disturbances in the segmentation process.

  15. Saltstone Osmotic Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Nichols, Ralph L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Dixon, Kenneth L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRN

    2013-09-23

    Recent research into the moisture retention properties of saltstone suggest that osmotic pressure may play a potentially significant role in contaminant transport (Dixon et al., 2009 and Dixon, 2011). The Savannah River Remediation Closure and Disposal Assessments Group requested the Savannah River National Laboratory (SRNL) to conduct a literature search on osmotic potential as it relates to contaminant transport and to develop a conceptual model of saltstone that incorporates osmotic potential. This report presents the findings of the literature review and presents a conceptual model for saltstone that incorporates osmotic potential. The task was requested through Task Technical Request HLW-SSF-TTR- 2013-0004.

  16. Performance of the Amoeba Distributed Operating System

    NARCIS (Netherlands)

    van Renesse, R.; van Staveren, H.; Tanenbaum, A.S.

    1989-01-01

    Amoeba is a capability‐based distributed operating system designed for high‐performance interactions between clients and servers using the well‐known RPC model. The paper starts out by describing the architecture of the Amoeba system, which is typified by specialized components such as workstations,

  17. Saltstone Osmotic Pressure

    International Nuclear Information System (INIS)

    Nichols, Ralph L.; Dixon, Kenneth L.

    2013-01-01

    Recent research into the moisture retention properties of saltstone suggest that osmotic pressure may play a potentially significant role in contaminant transport (Dixon et al., 2009 and Dixon, 2011). The Savannah River Remediation Closure and Disposal Assessments Group requested the Savannah River National Laboratory (SRNL) to conduct a literature search on osmotic potential as it relates to contaminant transport and to develop a conceptual model of saltstone that incorporates osmotic potential. This report presents the findings of the literature review and presents a conceptual model for saltstone that incorporates osmotic potential. The task was requested through Task Technical Request HLW-SSF-TTR-2013-0004. Simulated saltstone typically has very low permeability (Dixon et al. 2008) and pore water that contains a large concentration of dissolved salts (Flach and Smith 2013). Pore water in simulated saltstone has a high salt concentration relative to pore water in concrete and groundwater. This contrast in salt concentration can generate high osmotic pressures if simulated saltstone has the properties of a semipermeable membrane. Estimates of osmotic pressure using results from the analysis of pore water collected from simulated saltstone show that an osmotic pressure up to 2790 psig could be generated within the saltstone. Most semi-permeable materials are non-ideal and have an osmotic efficiency 3 , KNO 3 , Na 3 PO 4 x12H 2 O, and K 3 PO 4 when exposed to a dilute solution. Typically hydraulic head is considered the only driving force for groundwater in groundwater models. If a low permeability material containing a concentrated salt solution is present in the hydrogeologic sequence large osmotic pressures may develop and lead to misinterpretation of groundwater flow and solute transport. The osmotic pressure in the semi-permeable material can significantly impact groundwater flow in the vicinity of the semi-permeable material. One possible outcome is that

  18. How do amoebae swim and crawl?

    Directory of Open Access Journals (Sweden)

    Jonathan D Howe

    Full Text Available The surface behaviour of swimming amoebae was followed in cells bearing a cAR1-paGFP (cyclic AMP receptor fused to a photoactivatable-GFP construct. Sensitized amoebae were placed in a buoyant medium where they could swim toward a chemoattractant cAMP source. paGFP, activated at the cell's front, remained fairly stationary in the cell's frame as the cell advanced; the label was not swept rearwards. Similar experiments with chemotaxing cells attached to a substratum gave the same result. Furthermore, if the region around a lateral projection near a crawling cell's front is marked, the projection and the labelled cAR1 behave differently. The label spreads by diffusion but otherwise remains stationary in the cell's frame; the lateral projection moves rearwards on the cell (remaining stationary with respect to the substrate, so that it ends up outside the labelled region. Furthermore, as cAR1-GFP cells move, they occasionally do so in a remarkably straight line; this suggests they do not need to snake to move on a substratum. Previously, we suggested that the surface membrane of a moving amoeba flows from front to rear as part of a polarised membrane trafficking cycle. This could explain how swimming amoebae are able to exert a force against the medium. Our present results indicate that, in amoebae, the suggested surface flow does not exist: this implies that they swim by shape changes.

  19. Amoebas of Complex Hypersurfaces in Statistical Thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Passare, Mikael [Stockholm University, Department of Mathematics (Sweden); Pochekutov, Dmitry, E-mail: potchekutov@gmail.com [Siberian Federal University, Institute of Core Undergraduate Programmes (Russian Federation); Tsikh, August, E-mail: atsikh@sfu-kras.ru [Siberian Federal University, Institute of Mathematics (Russian Federation)

    2013-03-15

    The amoeba of a complex hypersurface is its image under the logarithmic projection. A number of properties of algebraic hypersurface amoebas are carried over to the case of transcendental hypersurfaces. We demonstrate the potential that amoebas can bring into statistical physics by considering the problem of energy distribution in a quantum thermodynamic ensemble. The spectrum {l_brace}{epsilon}{sub k}{r_brace} Subset-Of Z{sup n} of the ensemble is assumed to be multidimensional; this leads us to the notions of multidimensional temperature and a vector of differential thermodynamic forms. Strictly speaking, in the paper we develop the multidimensional Darwin-Fowler method and give the description of the domain of admissible average values of energy for which the thermodynamic limit exists.

  20. Biodiversity of amoebae and amoebae-resisting bacteria in a drinking water treatment plant.

    Science.gov (United States)

    Thomas, Vincent; Loret, Jean-François; Jousset, Michel; Greub, Gilbert

    2008-10-01

    The complex ecology of free-living amoebae (FLA) and their role in spreading pathogenic microorganisms through water systems have recently raised considerable interest. In this study, we investigated the presence of FLA and amoebae-resisting bacteria (ARB) at various stages of a drinking water plant fed with river water. We isolated various amoebal species from the river and from several points within the plant, mostly at early steps of water treatment. Echinamoeba- and Hartmannella-related amoebae were mainly recovered in the drinking water plant whereas Acanthamoeba- and Naegleria-related amoebae were recovered from the river water and the sand filtration units. Some FLA isolates were recovered immediately after the ozonation step, thus suggesting resistance of these microorganisms to this disinfection procedure. A bacterial isolate related to Mycobacterium mucogenicum was recovered from an Echinamoeba-related amoeba isolated from ozone-treated water. Various other ARB were recovered using co-culture with axenic Acanthamoeba castellanii, including mycobacteria, legionella, Chlamydia-like organisms and various proteobacteria. Noteworthy, a new Parachlamydia acanthamoebae strain was recovered from river water and from granular activated carbon (GAC) biofilm. As amoebae mainly multiply in sand and GAC filters, optimization of filter backwash procedures probably offers a possibility to better control these protists and the risk associated with their intracellular hosts.

  1. Experiences with the Amoeba distributed operating system

    NARCIS (Netherlands)

    Tanenbaum, Andrew S.; van Renesse, Robbert; van Staveren, Hans; Sharp, Gregory J.; Mullender, Sape J.; Jansen, Jack; van Rossum, Guido

    1990-01-01

    The Amoeba project is a research effort aimed at understanding how to connect multiple computers in a seamless way [16, 17, 26, 27, 31]. The basic idea is to provide the users with the illusion of a single powerful timesharing system, when, in fact, the system is implemented on a collection of

  2. Osmotic buckling of spherical capsules.

    Science.gov (United States)

    Knoche, Sebastian; Kierfeld, Jan

    2014-11-07

    We study the buckling of elastic spherical shells under osmotic pressure with the osmolyte concentration of the exterior solution as a control parameter. We compare our results for the bifurcation behavior with results for buckling under mechanical pressure control, that is, with an empty capsule interior. We find striking differences for the buckling states between osmotic and mechanical buckling. Mechanical pressure control always leads to fully collapsed states with opposite sides in contact, whereas uncollapsed states with a single finite dimple are generic for osmotic pressure control. For sufficiently large interior osmolyte concentrations, osmotic pressure control is qualitatively similar to buckling under volume control with the volume prescribed by the osmolyte concentrations inside and outside the shell. We present a quantitative theory which also captures the influence of shell elasticity on the relationship between osmotic pressure and volume. These findings are relevant for the control of buckled shapes in applications. We show how the osmolyte concentration can be used to control the volume of buckled shells. An accurate analytical formula is derived for the relationship between the osmotic pressure, the elastic moduli and the volume of buckled capsules. This also allows use of elastic capsules as osmotic pressure sensors or deduction of elastic properties and the internal osmolyte concentration from shape changes in response to osmotic pressure changes. We apply our findings to published experimental data on polyelectrolyte capsules.

  3. Infection and Proliferation of Giant Viruses in Amoeba Cells.

    Science.gov (United States)

    Takemura, Masaharu

    2016-01-01

    Acanthamoeba polyphaga mimivirus, the first discovered giant virus with genome size and particle size much larger than previously discovered viruses, possesses several genes for translation and CRISPER Cas system-like defense mechanism against virophages, which co-infect amoeba cells with the giant virus and which inhibit giant virus proliferation. Mimiviruses infect amoeba cells by phagocytosis and release their DNA into amoeba cytoplasm through their stargate structure. After infection, giant virion factories (VFs) form in amoeba cytoplasm, followed by DNA replication and particle formation at peripheral regions of VF. Marseilleviruses, the smallest giant viruses, infect amoeba cells by phagocytosis or endocytosis, form larger VF than Mimivirus's VF in amoeba cytoplasm, and replicate their particles. Pandoraviruses found in 2013 have the largest genome size and particle size among all viruses ever found. Pandoraviruses infect amoeba cells by phagocytosis and release their DNA into amoeba cytoplasm through their mouth-like apical pores. The proliferation of Pandoraviruses occurs along with nucleus disruption. New virions form at the periphery of the region formerly occupied by the amoeba cell nucleus.

  4. Revised Parameters for the AMOEBA Polarizable Atomic Multipole Water Model.

    Science.gov (United States)

    Laury, Marie L; Wang, Lee-Ping; Pande, Vijay S; Head-Gordon, Teresa; Ponder, Jay W

    2015-07-23

    A set of improved parameters for the AMOEBA polarizable atomic multipole water model is developed. An automated procedure, ForceBalance, is used to adjust model parameters to enforce agreement with ab initio-derived results for water clusters and experimental data for a variety of liquid phase properties across a broad temperature range. The values reported here for the new AMOEBA14 water model represent a substantial improvement over the previous AMOEBA03 model. The AMOEBA14 model accurately predicts the temperature of maximum density and qualitatively matches the experimental density curve across temperatures from 249 to 373 K. Excellent agreement is observed for the AMOEBA14 model in comparison to experimental properties as a function of temperature, including the second virial coefficient, enthalpy of vaporization, isothermal compressibility, thermal expansion coefficient, and dielectric constant. The viscosity, self-diffusion constant, and surface tension are also well reproduced. In comparison to high-level ab initio results for clusters of 2-20 water molecules, the AMOEBA14 model yields results similar to AMOEBA03 and the direct polarization iAMOEBA models. With advances in computing power, calibration data, and optimization techniques, we recommend the use of the AMOEBA14 water model for future studies employing a polarizable water model.

  5. [Extrapontine osmotic myelinolysis].

    Science.gov (United States)

    Silva, Federico A; Rueda-Clausen, Christian F; Ramírez, Fabián

    2005-06-01

    Extrapontine osmotic myelinolysis is a rare nervous system complication. Symptoms of this malady were presented during the clinical examination of a 49-year-old alcoholic male, who arrived at the hospital emergency room in a state of cardiorespiratory arrest. After resuscitation methods were applied, the patient was found in metabolic acidosis (pH 7.014) and was treated with sodium bicarbonate. Forty-eight hours later, sodium levels in the patient had risen from 142 to 174 mEq/l. During the period of clinical observation, the patient showed signs of cognitive impairment, disartria, bilateral amaurosis, hyporeflexia and right-half body hemiparesias. After 72 hours, computer tomography was applied; this showed a bilateral lenticular hypodensity with internal and external capsule compromise. One month later, when the patient was referred to another institution for rehabilitation, the patient showed cognitive impairment, bilateral optic atrophy, residual disartria, bradikynesia and double hemiparesia.

  6. Osmotic water transport in aquaporins

    DEFF Research Database (Denmark)

    Zeuthen, Thomas; Alsterfjord, Magnus; Beitz, Eric

    2013-01-01

    Abstract  We test a novel, stochastic model of osmotic water transport in aquaporins. A solute molecule present at the pore mouth can either be reflected or permeate the pore. We assume that only reflected solute molecules induce osmotic transport of water through the pore, while permeating solute...... molecules give rise to no water transport. Accordingly, the rate of water transport is proportional to the reflection coefficient σ, while the solute permeability, P(S), is proportional to 1 - σ. The model was tested in aquaporins heterologously expressed in Xenopus oocytes. A variety of aquaporin channel...... sizes and geometries were obtained with the two aquaporins AQP1 and AQP9 and mutant versions of these. Osmotic water transport was generated by adding 20 mM of a range of different-sized osmolytes to the outer solution. The osmotic water permeability and the reflection coefficient were measured...

  7. Sucker-like structures on the pathogenic amoeba Naegleria fowleri.

    OpenAIRE

    John, D T; Cole, T B; Marciano-Cabral, F M

    1984-01-01

    Using scanning electron microscopy, we observed sucker-like structures on amoebae of 13 human isolates of Naegleria fowleri. The number of suckers per amoeba seemed to vary according to the virulence of the strain. We propose the term amoebastome to describe this unique sucker-like structure of N. fowleri.

  8. Amoeba: a distributed operating system for the 1990s

    NARCIS (Netherlands)

    Mullender, Sape J.; van Rossum, Guido; Tanenbaum, Andrew S.; van Renesse, Robbert; van Staveren, Hans

    A description is given of the Amoeba distributed operating system, which appears to users as a centralized system but has the speed, fault tolerance, security safeguards, and flexibility required for the 1990s. The Amoeba software is based on objects. Objects are managed by server processes and

  9. Amoeba: A Distributed Operating System for the 1990s

    NARCIS (Netherlands)

    Mullender, S.J.; van Rossum, G.; Tanenbaum, A.S.; van Renesse, R.; van Staveren, H.

    1990-01-01

    A description is given of the Amoeba distributed operating system, which appears to users as a centralized system but has the speed, fault tolerance, security safeguards, and flexibility required for the 1990s. The Amoeba software is based on objects. Objects are managed by server processes and

  10. Cocultivation of Legionella pneumophila and free-living amoebae.

    Science.gov (United States)

    Tyndall, R L; Domingue, E L

    1982-10-01

    Studies of the interaction of Legionella pneumophila with free-living amoebae showed that Naegleria lovaniensis and Acanthamoeba royreba could use L. pneumophila as a sole food source. However, growth of the amoebae on nonnutrient agar plates seeded with L. pneumophila was slower than growth on nonnutrient agar plates seeded with Escherichia coli. On inoculation of L. pneumophila into axenic cultures of N. lovaniensis and A. royreba, 99.9% of the L. pneumophila was destroyed within 24 h. After several weeks, however, some amoeba cultures became chronically infected and supported the growth of L. pneumophila. Amoebae exposed to L. pneumophila and containing adhered L. pneumophila, L. pneumophila antigens, or both, showed no increased pathogenic potential on intranasal inoculation of weanling mice. Similarly, L. pneumophila propagated in chronically infected amoeba cultures showed no increase in virulence on intraperitoneal inoculation of guinea pigs relative to L. pneumophila grown in yeast extract broth.

  11. Cocultivation of Legionella pneumophila and free-living amoebae

    Energy Technology Data Exchange (ETDEWEB)

    Tyndall, R.L.; Domingue, E.L.

    1982-10-01

    Studies of the interaction of Legionella pneumophila with free-living amoebae showed that Naegleria lovaniensis and Acanthamoeba royreba could use L. pneumophia as a sole food source. However, growth of the amoebae on nonnutrient agar plates seeded with L. pneumophila was slower than growth on nonnutrient agar plates seeded with Escherichia coli. On inoculation of L. pneumophila into axenic cultures of N. lovaniensis and A. roryba, 99.9% of the L. pneumophila was destroyed within 24 h. After several weeks, however, some amoeba cultures became chronically infected and supported the growth of L. pneumophila. Amoebae exposed to L. pneumophila and containing adhered L. pneumophila, L. pneumophila antigens, or both, showed no increased pathogenic potential on intranasal inoculation of weanling mice. Similarly, L. pneumophila propagated in chronically infected amoeba cultures showed no increase in virulence on intraperitoneal inoculation of guinea pigs relative to L. pneumophila grown in yeast extract broth. 20 references, 1 figure, 4 tables.

  12. Neutral lipid production in Dunaliella salina during osmotic stress and adaptation

    DEFF Research Database (Denmark)

    Yao, Shuo; Lu, Jingquan; Sárossy, Zsuzsa

    2016-01-01

    The salt-tolerant green microalga Dunaliella salina can survive both hyper- and hypo-osmotic shock. Upon osmotic shock, the cells transiently and rapidly decreased or increased in size within minutes and slowly over hours acquired their original cell size and volume. Cell size distribution differs...... in salt concentration did not significantly influence the overall fatty acid composition in D. salina cells. Although there shows both increased amounts of total lipids and neutral lipids in the cells grown in salinity higher than 9 % NaCl, lipid productivity is however compromised by the slower cell...

  13. Multiplication rate of amoebae related to the cultivation temperature

    Energy Technology Data Exchange (ETDEWEB)

    Sopina, V.A.

    1976-10-01

    The cultivation temperature-dependent rate of multiplication in amoebae was studied using three strains of Amoeba proteus and another amoeba strain of unknown specific and generic position. The multiplication rates are characterized by optima that vary with strains. The temperature-induced changes in the multiplication rate of a given strain are non-hereditary; they are common modifications. Hereditary interstrain differences in the multiplication rate have also been shown at constant temperatures. The range of modificational changes with increase or decrease of cultivation temperature appears to be greater than interstrain differences in multiplication rate.

  14. Efficiency of osmotic pipe flows

    DEFF Research Database (Denmark)

    Haaning, Louise Sejling; Jensen, Kaare Hartvig; Helix Nielsen, Claus

    2013-01-01

    on the relative magnitude of radial diffusion and advection as well as the ratio of the osmotic velocity to pumping velocity, in very good agreement with experiments and with no adjustable parameters. Our analysis provides criteria that are useful for optimizing osmotic flow processes in, e.g., water purification......We present experiments and theory for flows of sugar or salt solutions in cylindrical tubes with semipermeable walls (hollow fiber membranes) immersed in water, quantifying the strength of the osmotic driving force in relation to the dimensionless parameters that specify the system. The pumping...... efficiency of these flows is limited by the presence of “unstirred” concentration boundary layers near the tube walls, and our primary aim is to understand and quantify these layers and their effect on the flow. We measure the outlet flow rate Qout while varying the inlet flow rate Q*, concentration c...

  15. Role of Osmotic Adjustment in Plant Productivity

    Energy Technology Data Exchange (ETDEWEB)

    Gebre, G.M.

    2001-01-11

    Successful implementation of short rotation woody crops requires that the selected species and clones be productive, drought tolerant, and pest resistant. Since water is one of the major limiting factors in poplar (Populus sp.) growth, there is little debate for the need of drought tolerant clones, except on the wettest of sites (e.g., lower Columbia River delta). Whether drought tolerance is compatible with productivity remains a debatable issue. Among the many mechanisms of drought tolerance, dehydration postponement involves the maintenance of high leaf water potential due to, for example, an adequate root system. This trait is compatible with productivity, but requires available soil moisture. When the plant leaf water potential and soil water content decline, the plant must be able to survive drought through dehydration tolerance mechanisms, such as low osmotic potential or osmotic adjustment. Osmotic adjustment and low osmotic potential are considered compatible with growth and yield because they aid in the maintenance of leaf turgor. However, it has been shown that turgor alone does not regulate cell expansion or stomatal conductance and, therefore, the role of osmotic adjustment is debated. Despite this finding, osmotic adjustment has been correlated with grain yield in agronomic crop species, and gene markers responsible for osmotic adjustment are being investigated to improve drought tolerance in productive progenies. Although osmotic adjustment and low osmotic potentials have been investigated in several forest tree species, few studies have investigated the relationship between osmotic adjustment and growth. Most of these studies have been limited to greenhouse or container-grown plants. Osmotic adjustment and rapid growth have been specifically associated in Populus and black spruce (Picea mariuna (Mill.) B.S.P.) progenies. We tested whether these relationships held under field conditions using several poplar clones. In a study of two hybrid poplar

  16. Buse_Francisella and free-living amoebae data sets

    Data.gov (United States)

    U.S. Environmental Protection Agency — Co-infection data in the form of colony forming units and amoeba cell counts. This dataset is associated with the following publication: Buse , H., F. Schaefer, and...

  17. Osmotic Effects in Sludge Dewatering

    DEFF Research Database (Denmark)

    Keiding, Kristian; Rasmussen, Michael R.

    2003-01-01

    A model of filtration dewatering is presented. The model is based on the d’Arcy flow equation in which the resistance to filtration is described by the Corzeny–Carman equation and the driving force is the difference between the external pressure and the osmotic pressure of the filter cake. It has...

  18. Phylogeny, evolution, and taxonomy of vannellid amoebae.

    Science.gov (United States)

    Smirnov, Alexey V; Nassonova, Elena S; Chao, Ema; Cavalier-Smith, Thomas

    2007-07-01

    We sequenced 18S rRNA genes from 21 vannellid amoebae (Amoebozoa; Vannellidae), including nearly all available type cultures, and performed a comprehensive phylogenetic analysis for 57 Vannellidae sequences. The results show that species of Vannella and Platyamoeba are completely mixed and do not form distinct clades. Several very closely related species pairs exist, each with a Vannella and a Platyamoeba species differing in only a few nucleotides. Therefore, presence (Vannella) or absence (Platyamoeba) of glycostyles in the cell surface coat is an invalid generic distinction; the genera must be merged. As Vannella has priority, we formally transferred Platyamoeba species into Vannella, except for the non-vannellid P. stenopodia, here renamed Stenamoeba stenopodia gen. n. comb. n. and transferred to the family Thecamoebidae. Our trees show that Vannella glycostyles were probably easily and repeatedly evolutionarily lost. We have established a new genus Ripella, with distinct morphology and sequence signatures for Vannella platypodia and morphologically similar species that form a clearly separate clade, very distant from other Vannellidae. Vannellids form four well-separated single-genus clades: Vannella sensu stricto, Ripella, Clydonella, and Lingulamoeba. Species of the revised genus Vannella comprise four closely related, well-supported subclades: one marine and three freshwater. Here, we provide an illustrated checklist for all 40 known Vannellidae species.

  19. Cell Wall Remodeling Enzymes Modulate Fungal Cell Wall Elasticity and Osmotic Stress Resistance.

    Science.gov (United States)

    Ene, Iuliana V; Walker, Louise A; Schiavone, Marion; Lee, Keunsook K; Martin-Yken, Hélène; Dague, Etienne; Gow, Neil A R; Munro, Carol A; Brown, Alistair J P

    2015-07-28

    The fungal cell wall confers cell morphology and protection against environmental insults. For fungal pathogens, the cell wall is a key immunological modulator and an ideal therapeutic target. Yeast cell walls possess an inner matrix of interlinked β-glucan and chitin that is thought to provide tensile strength and rigidity. Yeast cells remodel their walls over time in response to environmental change, a process controlled by evolutionarily conserved stress (Hog1) and cell integrity (Mkc1, Cek1) signaling pathways. These mitogen-activated protein kinase (MAPK) pathways modulate cell wall gene expression, leading to the construction of a new, modified cell wall. We show that the cell wall is not rigid but elastic, displaying rapid structural realignments that impact survival following osmotic shock. Lactate-grown Candida albicans cells are more resistant to hyperosmotic shock than glucose-grown cells. We show that this elevated resistance is not dependent on Hog1 or Mkc1 signaling and that most cell death occurs within 10 min of osmotic shock. Sudden decreases in cell volume drive rapid increases in cell wall thickness. The elevated stress resistance of lactate-grown cells correlates with reduced cell wall elasticity, reflected in slower changes in cell volume following hyperosmotic shock. The cell wall elasticity of lactate-grown cells is increased by a triple mutation that inactivates the Crh family of cell wall cross-linking enzymes, leading to increased sensitivity to hyperosmotic shock. Overexpressing Crh family members in glucose-grown cells reduces cell wall elasticity, providing partial protection against hyperosmotic shock. These changes correlate with structural realignment of the cell wall and with the ability of cells to withstand osmotic shock. The C. albicans cell wall is the first line of defense against external insults, the site of immune recognition by the host, and an attractive target for antifungal therapy. Its tensile strength is conferred by

  20. Pathogenic Free-Living Amoebae Isolated From Contact Lenses of Keratitis Patients

    OpenAIRE

    HAJIALILO, Elham; NIYYATI, Maryam; SOLAYMANI, Mohammad; REZAEIAN, Mostafa

    2015-01-01

    Background: Free-living amoeba (FLA)-related keratitis is a progressive infection of the cornea with poor prognosis. The present study aimed to investigates the con­tact lenses of patients with keratitis for pathogenic free-living amoebae.Methods: Overall, 62 contact lenses and their paraphernalia of patients with kerati­tis cultured and tested for the presence of free-living amoebae using morphological criteria. Unusual plates including plates containing mix amoebae and Vermamoeba were submi...

  1. Selective Osmotic Shock (SOS)-Based Islet Isolation for Microencapsulation.

    Science.gov (United States)

    Enck, Kevin; McQuilling, John Patrick; Orlando, Giuseppe; Tamburrini, Riccardo; Sivanandane, Sittadjody; Opara, Emmanuel C

    2017-01-01

    Islet transplantation (IT) has recently been shown to be a promising alternative to pancreas transplantation for reversing diabetes. IT requires the isolation of the islets from the pancreas, and these islets can be used to fabricate a bio-artificial pancreas. Enzymatic digestion is the current gold standard procedure for islet isolation but has lingering concerns. One such concern is that it has been shown to damage the islets due to nonselective tissue digestion. This chapter provides a detailed description of a nonenzymatic method that we are exploring in our lab as an alternative to current enzymatic digestion procedures for islet isolation from human and nonhuman pancreatic tissues. This method is based on selective destruction and protection of specific cell types and has been shown to leave the extracellular matrix (ECM) of islets intact, which may thus enhance islet viability and functionality. We also show that these SOS-isolated islets can be microencapsulated for transplantation.

  2. Parasitic amoebae found in water bodies of Ukraine.

    Science.gov (United States)

    Patsyuk, Marina

    2017-12-01

    Two parasitic amoebian species are found in mollusks of the water bodies of Ukraine. Vahlkampfia sp. is found in hepatopankreas of Unio conus Spengler, 1793, and Acanthamoeba sp. is observed in mantle cavity of Viviparus viviparus Linnaeus, 1758. For these protist species, the mollusks are shown to be intermediate hosts where amoebae feed and reproduce. An experimental infection with Vahlkampfia sp. and Acanthamoeba sp. was not successful, no pathological changes in mollusks were observed. These amoebae are successfully cultured in fresh water and agar medium, hence we can safely consider them free-living. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Fouling in Membrane Distillation, Osmotic Distillation and Osmotic Membrane Distillation

    Directory of Open Access Journals (Sweden)

    Mourad Laqbaqbi

    2017-03-01

    Full Text Available Various membrane separation processes are being used for seawater desalination and treatment of wastewaters in order to deal with the worldwide water shortage problem. Different types of membranes of distinct morphologies, structures and physico-chemical characteristics are employed. Among the considered membrane technologies, membrane distillation (MD, osmotic distillation (OD and osmotic membrane distillation (OMD use porous and hydrophobic membranes for production of distilled water and/or concentration of wastewaters for recovery and recycling of valuable compounds. However, the efficiency of these technologies is hampered by fouling phenomena. This refers to the accumulation of organic/inorganic deposits including biological matter on the membrane surface and/or in the membrane pores. Fouling in MD, OD and OMD differs from that observed in electric and pressure-driven membrane processes such electrodialysis (ED, membrane capacitive deionization (MCD, reverse osmosis (RO, nanofiltration (NF, ultrafiltration (UF, microfiltration (MF, etc. Other than pore blockage, fouling in MD, OD and OMD increases the risk of membrane pores wetting and reduces therefore the quantity and quality of the produced water or the concentration efficiency of the process. This review deals with the observed fouling phenomena in MD, OD and OMD. It highlights different detected fouling types (organic fouling, inorganic fouling and biofouling, fouling characterization techniques as well as various methods of fouling reduction including pretreatment, membrane modification, membrane cleaning and antiscalants application.

  4. The physics of osmotic pressure

    Science.gov (United States)

    Bowler, M. G.

    2017-09-01

    Osmosis drives the development of a pressure difference of many atmospheres between a dilute solution and pure solvent with which it is in contact through a semi-permeable membrane. The educational importance of this paper is that it presents a novel treatment in terms of fluid mechanics that is quantitative and exact. It is also simple and intuitive, showing vividly how osmotic pressures are generated and maintained in equilibrium, driven by differential solvent pressures. The present rigorous analysis using the virial theorem seems unknown and can be easily understood—and taught—at various different levels. It should be valuable to undergraduates, graduate students and indeed to the general physicist.

  5. The Evolution of a distributed operating system (Amoeba)

    NARCIS (Netherlands)

    van Renesse, Robbert; Tanenbaum, Andrew S.; Mullender, Sape J.

    1989-01-01

    AMOEBA is a research project to build a true distributed operating system using the object model. Under the COST11-ter MANDIS project this work was extended to cover wide-area networks. Besides describing the system, this paper discusses the successive versions in the implementation of its model,

  6. Shifts in soil testate amoeba communities associated with forest diversification.

    Science.gov (United States)

    Bobrov, Anatoly A; Zaitsev, Andrei S; Wolters, Volkmar

    2015-05-01

    We studied changes of testate amoeba communities associated with the conversion of spruce monocultures into mixed beech-fir-spruce forests in the Southern Black Forest Mountains (Germany). In this region, forest conversion is characterized by a gradual development of beech undergrowth within thinned spruce tree stands leading to multiple age continuous cover forests with a diversified litter layer. Strong shifts in the abundance of testate amoeba observed in intermediate stages levelled off to monoculture conditions again after the final stage of the conversion process had been reached. The average number of species per conversion stage (i.e., local richness) did not respond strongly to forest conversion, but the total number of species (i.e., regional richness) was considerably higher in the initial stage than in the mixed forests, due to the large number of hygrophilous species inhabiting spruce monocultures. Functional diversity of the testate amoeba community, however, significantly increased during the conversion process. This shift was closely associated with improved C and N availability as well as higher niche diversity in the continuous cover stands. Lower soil acidity in these forests coincided with a higher relative abundance of eurytopic species. Our results suggest that testate amoeba communities are much more affected by physicochemical properties of the soil than directly by litter diversity.

  7. Elemental maps of Amoeba proteus by a scanning proton microprobe

    Energy Technology Data Exchange (ETDEWEB)

    Li Minqian; Zhu Jieqing; Huang Zeqi (Shanghai Inst. of Nuclear Research, Academia Sinica, SH (China)); Zhu Jingde; Zhou Zheng; Zhou Weiying (Shanghai Inst. of Cell Biology, Academia Sinica, SH (China)); Cholewa, M.; Legge, G.J.F. (Micro Analytical Research Centre, Univ. of Melbourne, School of Physics, Parkville (Australia))

    1991-03-01

    Elemental maps for P, S, Cl, K, Ca and Zn of individual Amoeba proteus were obtained with the Melbourne scanning proton microprobe. The emphasis was put on the relationship of both distribution and concentration of Zn within the cell and the growth inhibitory effect of higher Zn concentrations in the culture medium. At a concentration of 0.04 mmol ZnCl{sub 2}. Amoeba growth was inhibited. But at a concentration of 0.0016 mmol, the Amoeba grew as well as a control grown without addition of Zn. We found that in the former (0.04 mmol) Zn concentrated three times more than in the latter (0.0016 mmol), and also that Zn was enriched much more in the nucleus and endoplasm (five to six times) than in other parts of the cell (two times). Future work along these lines may provide insight into the mechanism by which Zn affects the growth of Amoeba proteus and other cells. (orig.).

  8. A Comparison of Two Distributed Systems: Amoeba and Sprite

    NARCIS (Netherlands)

    Douglis, F.; Ousterhout, J.K.; Kaashoek, M.F.; Tanenbaum, A.S.

    This paper compares two distributed operating systems, Amoeba and Sprite. Although the systems share many goals, they diverged on two philosophical grounds: whether to emphasize a distributed computing model or traditional UNIX-style applications, and whether to use a workstation-centered model of

  9. Methodology to Implement an Amoeba Complex Object Server

    NARCIS (Netherlands)

    Teeuw, Wouter B.; Blanken, Henk

    The paper describes the methodology used in the design of a complex object server application for the Amoeba distributed operating system. It uses the top-down design that was suggested by Parnas, in which a model is turned into an implementation by gradually adding details. The paper also describes

  10. AIL - a class-oriented RPC stub generator for Amoeba

    NARCIS (Netherlands)

    G. van Rossum (Guido)

    1989-01-01

    textabstractAIL – an acronym for Amoeba Interface Language – is a class-oriented RPC stub generator, used with Amoeba’s RPC primitives. Together with Amoeba’s facilities for manipulating capabilities (bit patterns that are unforgeable references to objects maintained by servers anywhere on a

  11. The genome of the social amoeba Dictyostelium discoideum

    DEFF Research Database (Denmark)

    Eichinger, L; Pachebat, J A; Glöckner, G

    2005-01-01

    The social amoebae are exceptional in their ability to alternate between unicellular and multicellular forms. Here we describe the genome of the best-studied member of this group, Dictyostelium discoideum. The gene-dense chromosomes of this organism encode approximately 12,500 predicted proteins,...

  12. Advances in the knowledge of amphizoic amoebae infecting fish

    Czech Academy of Sciences Publication Activity Database

    Dyková, Iva; Lom, Jiří

    2004-01-01

    Roč. 51, 2/3 (2004), s. 81-97 ISSN 0015-5683 R&D Projects: GA AV ČR IAA6022202 Institutional research plan: CEZ:AV0Z6022909 Keywords : amphizoic amoebae * fish hosts * review Subject RIV: EA - Cell Biology Impact factor: 0.837, year: 2004

  13. Diagnosis of Infections Caused by Pathogenic Free-Living Amoebae

    Directory of Open Access Journals (Sweden)

    Bruno da Rocha-Azevedo

    2009-01-01

    Full Text Available Naegleria fowleri, Acanthamoeba spp., Balamuthia mandrillaris, and Sappinia sp. are pathogenic free-living amoebae. N. fowleri causes Primary Amoebic Meningoencephalitis, a rapidly fatal disease of the central nervous system, while Acanthamoeba spp. and B. mandrillaris cause chronic granulomatous encephalitis. Acanthamoeba spp. also can cause cutaneous lesions and Amoebic Keratitis, a sight-threatening infection of the cornea that is associated with contact lens use or corneal trauma. Sappinia pedata has been identified as the cause of a nonlethal case of amoebic encephalitis. In view of the potential health consequences due to infection with these amoebae, rapid diagnosis is critical for early treatment. Microscopic examination and culture of biopsy specimens, cerebral spinal fluid (CSF, and corneal scrapings have been used in the clinical laboratory. For amoebic keratitis, confocal microscopy has been used to successfully identify amoebae in corneal tissue. More recently, conventional and real-time PCR assays have been developed that are sensitive and specific for the amoebae. In addition, multiplex PCR assays are available for the rapid identification of these pathogens in biopsy tissue, CSF, and corneal specimens.

  14. Inactivation and Removal of Free-Living Amoebae.

    Science.gov (United States)

    Free-living amoebae (FLA) are ubiquitous protozoan that are predominantly harmless to humans. There are a few genera that cause disease in humans, Balamuthia, Naegleria, and Acanthamoeba. These organisms are not easily removed by physical means or inactivated by chemic...

  15. Counting Legionella cells within single amoeba host cells

    Science.gov (United States)

    Here we present the first attempt to quantify L. pneumophila cell numbers within individual amoebae hosts that may be released into engineered water systems. The maximum numbers of culturable L. pneumophila cells grown within Acanthamoeba polyphaga and Naegleria fowleri were 134...

  16. Osmotic homeostasis and NKLy lymphoma cells radiosensitivity

    International Nuclear Information System (INIS)

    Tishchenko, V.V.; Magda, I.N.

    1992-01-01

    In experiments with cells of ascites NKLy lymphoma differing in ploidy and position in the cell cycle, a study was made of the radiosensitivity, osmotic homeostasis peculiarities and thermoradiation changes in potassium content. It was shown that the resistance of osmotic homeostasis of NKLy cells to thermoradiation correlated with their radioresistance

  17. Physicochemical characteristics of osmotically dehydrated tomato ...

    African Journals Online (AJOL)

    Physicochemical characteristics of osmotically dehydrated tomato (Lycopersicon esculentum) under different common drying methods. JAV Famurewa, AO Raji. Abstract. This study investigated the effect of different common drying methods on the chemical composition of osmotically dehydrated tomato. The quality of ...

  18. Surveillance of parasitic Legionella in surface waters by using immunomagnetic separation and amoebae enrichment.

    Science.gov (United States)

    Hsu, Tsui-Kang; Wu, Shu-Fen; Hsu, Bing-Mu; Kao, Po-Min; Tao, Chi-Wei; Shen, Shu-Min; Ji, Wen-Tsai; Huang, Wen-Chien; Fan, Cheng-Wei

    2015-01-01

    Free-living amoebae (FLA) are potential reservoirs of Legionella in aquatic environments. However, the parasitic relationship between various Legionella and amoebae remains unclear. In this study, surface water samples were gathered from two rivers for evaluating parasitic Legionella. Warmer water temperature is critical to the existence of Legionella. This result suggests that amoebae may be helpful in maintaining Legionella in natural environments because warmer temperatures could enhance parasitisation of Legionella in amoebae. We next used immunomagnetic separation (IMS) to identify extracellular Legionella and remove most free Legionella before detecting the parasitic ones in selectively enriched amoebae. Legionella pneumophila was detected in all the approaches, confirming that the pathogen is a facultative amoebae parasite. By contrast, two obligate amoebae parasites, Legionella-like amoebal pathogens (LLAPs) 8 and 9, were detected only in enriched amoebae. However, several uncultured Legionella were detected only in the extracellular samples. Because the presence of potential hosts, namely Vermamoeba vermiformis, Acanthamoeba spp. and Naegleria gruberi, was confirmed in the samples that contained intracellular Legionella, uncultured Legionella may survive independently of amoebae. Immunomagnetic separation and amoebae enrichment may have referential value for detecting parasitic Legionella in surface waters.

  19. Protozoa inhibition by different salts: Osmotic stress or ionic stress?

    Science.gov (United States)

    Li, Changhao; Li, Jingya; Lan, Christopher Q; Liao, Dankui

    2017-09-01

    Cell density and morphology changes were tested to examine the effects of salts including NaHCO 3 , NaCl, KHCO 3 , and KCl at 160 mM on protozoa. It was demonstrated that ionic stress rather than osmotic stress led to protozoa cell death and NaHCO 3 was shown to be the most effective inhibitor. Deformation of cells and cell shrinkage were observed when protozoan cells were exposed to polyethylene glycol (PEG) or any of the salts. However, while PEG treated cells could fully recover in both number and size, only a small portion of the salt-treated cells survive and cell size was 36-58% smaller than the regular. The disappearance of salt-treated protozoa cells was hypothetically attributed to disruption of the cytoplasmic membrane of these cells. It is further hypothesized that the PEG-treated protozoan cells carried out regulatory volume increase (RVI) after the osmotic shock but the RVI of salt-treated protozoa was hurdled to varied extents. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1418-1424, 2017. © 2017 American Institute of Chemical Engineers.

  20. Raman spectroscopic study on the excystation process in a single unicellular organism amoeba (Acanthamoeba polyphaga)

    Science.gov (United States)

    Lin, Yu-Chung; Perevedentseva, Elena; Cheng, Chia-Liang

    2015-05-01

    An in vivo Raman spectroscopic study of amoeba (Acanthamoeba polyphaga) is presented. The changes of the spectra during the amoeba cyst activation and excystation are analyzed. The spectra show the changes of the relative intensities of bands corresponding to protein, lipid, and carotenoid components during cyst activation. The presence of carotenoids in the amoeba is observed via characteristic Raman bands. These signals in the Raman spectra are intense in cysts but decrease in intensity with cyst activation and exhibit a correlation with the life cycle of amoeba. This work demonstrates the feasibility of using Raman spectroscopy for the detection of single amoeba microorganisms in vivo and for the analysis of the amoeba life activity. The information obtained may have implications for the estimation of epidemiological situations and for the diagnostics and prognosis of the development of amoebic inflammations.

  1. The Influence of the Osmotic Dehydration Process on Physicochemical Properties of Osmotic Solution

    Directory of Open Access Journals (Sweden)

    Krzysztof Lech

    2017-12-01

    Full Text Available The osmotic dehydration (OD process consists of the removal of water from a material during which the solids from the osmotic solution are transported to the material by osmosis. This process is commonly performed in sucrose and salt solutions. Taking into account that a relatively high consumption of those substances might have a negative effect on human health, attempts have been made to search for alternatives that can be used for osmotic dehydration. One of these is an application of chokeberry juice with proven beneficial properties to human health. This study aimed to evaluate the physicochemical properties of the OD solution (chokeberry juice concentrate before and after the osmotic dehydration of carrot and zucchini. The total polyphenolics content, antioxidant capacity (ABTS, FRAP, dynamic viscosity, density, and water activity were examined in relation to the juice concentration used for the osmotic solution before and after the OD process. During the osmotic dehydration process, the concentration of the chokeberry juice decreased. Compounds with lower molecular weight and lower antioxidant capacity present in concentrated chokeberry juice had a stronger influence on the exchange of compounds during the OD process in carrot and zucchini. The water activity of the osmotic solution increased after the osmotic dehydration process. It was concluded that the osmotic solution after the OD process might be successfully re-used as a product with high quality for i.e. juice production.

  2. The Influence of the Osmotic Dehydration Process on Physicochemical Properties of Osmotic Solution.

    Science.gov (United States)

    Lech, Krzysztof; Michalska, Anna; Wojdyło, Aneta; Nowicka, Paulina; Figiel, Adam

    2017-12-16

    The osmotic dehydration (OD) process consists of the removal of water from a material during which the solids from the osmotic solution are transported to the material by osmosis. This process is commonly performed in sucrose and salt solutions. Taking into account that a relatively high consumption of those substances might have a negative effect on human health, attempts have been made to search for alternatives that can be used for osmotic dehydration. One of these is an application of chokeberry juice with proven beneficial properties to human health. This study aimed to evaluate the physicochemical properties of the OD solution (chokeberry juice concentrate) before and after the osmotic dehydration of carrot and zucchini. The total polyphenolics content, antioxidant capacity (ABTS, FRAP), dynamic viscosity, density, and water activity were examined in relation to the juice concentration used for the osmotic solution before and after the OD process. During the osmotic dehydration process, the concentration of the chokeberry juice decreased. Compounds with lower molecular weight and lower antioxidant capacity present in concentrated chokeberry juice had a stronger influence on the exchange of compounds during the OD process in carrot and zucchini. The water activity of the osmotic solution increased after the osmotic dehydration process. It was concluded that the osmotic solution after the OD process might be successfully re-used as a product with high quality for i.e. juice production.

  3. Osmocapsules for direct measurement of osmotic strength.

    Science.gov (United States)

    Kim, Shin-Hyun; Lee, Tae Yong; Lee, Sang Seok

    2014-03-26

    Monodisperse microcapsules with ultra-thin membranes are microfluidically designed to be highly sensitive to osmotic pressure, thereby providing a tool for the direct measurement of the osmotic strength. To make such osmocapsules, water-in-oil-in-water double-emulsion drops with ultra-thin shells are prepared as templates through emulsification of core-sheath biphasic flow in a capillary microfluidic device. When photocurable monomers are used as the oil phase, the osmocapsules are prepared by in-situ photopolymerization of the monomers, resulting in semipermeable membranes with a relatively large ratio of membrane thickness to capsule radius, approximately 0.02. These osmocapsules are buckled by the outward flux of water when they are subjected to a positive osmotic pressure difference above 125 kPa. By contrast, evaporation-induced consolidation of middle-phase containing polymers enables the production of osmocapsules with a small ratio of membrane thickness to capsule radius of approximately 0.002. Such an ultra-thin membrane with semi-permeability makes the osmocapsules highly sensitive to osmotic pressure; a positive pressure as small as 12.5 kPa induces buckling of the capsules. By employing a set of distinct osmocapsules confining aqueous solutions with different osmotic strengths, the osmotic strength of unknown solutions can be estimated through observation of the capsules that are selectively buckled. This approach provides the efficient measurement of the osmotic strength using only a very small volume of liquid, thereby providing a useful alternative to other measurement methods which use complex setups. In addition, in-vivo measurement of the osmotic strength can be potentially accomplished by implanting these biocompatible osmocapsules into tissue, which is difficult to achieve using conventional methods. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Survival of taylorellae in the environmental amoeba Acanthamoeba castellanii.

    Science.gov (United States)

    Allombert, Julie; Vianney, Anne; Laugier, Claire; Petry, Sandrine; Hébert, Laurent

    2014-03-19

    Taylorella equigenitalis is the causative agent of contagious equine metritis, a sexually-transmitted infection of Equidae characterised in infected mares by abundant mucopurulent vaginal discharge and a variable degree of vaginitis, cervicitis or endometritis, usually resulting in temporary infertility. The second species of the Taylorella genus, Taylorella asinigenitalis, is considered non-pathogenic, although mares experimentally infected with this bacterium can develop clinical signs of endometritis. To date, little is understood about the basic molecular virulence and persistence mechanisms employed by the Taylorella species. To clarify these points, we investigated whether the host-pathogen interaction model Acanthamoeba castellanii was a suitable model for studying taylorellae. We herein demonstrate that both species of the Taylorella genus are internalised by a mechanism involving the phagocytic capacity of the amoeba and are able to survive for at least one week inside the amoeba. During this one-week incubation period, taylorellae concentrations remain strikingly constant and no overt toxicity to amoeba cells was observed. This study provides the first evidence of the capacity of taylorellae to survive in a natural environment other than the mammalian genital tract, and shows that the alternative infection model, A. castellanii, constitutes a relevant alternative system to assess host-pathogen interactions of taylorellae. The survival of taylorellae inside the potential environmental reservoir A. castellanii brings new insight, fostering a broader understanding of taylorellae biology and its potential natural ecological niche.

  5. Extra pontine osmotic demyelination syndrome.

    Science.gov (United States)

    Zunga, Pervaiz M; Farooq, Omar; Dar, Mohd I; Dar, Ishrat H; Rashid, Samia; Rather, Abdul Q; Basu, Javid A; Ashraf, Mohammed; Bhat, Jahangeer A

    2015-01-01

    The osmotic demyelination syndrome (ODS) has been identified as a complication of the rapid correction of hyponatremia for decades. However, in recent years, a variety of other medical conditions have been associated with the development of ODS, independent of changes in serum sodium which cause a rapid changes in osmolality of the interstitial (extracellular) compartment of the brain leading to dehydration of energy-depleted cells with subsequent axonal damage that occurs in characteristic areas. Slow correction of the serum sodium concentration and additional administration of corticosteroids seems to be a major prevention step in ODS patients. In the current report we aimed to share a rare case which we observed in our hospital. A 65 year old female admitted as altered sensorium with history of vomiting, diarrhea was managed with intravenous fluids for 2 days at a peripheral health centre. Patient was referred to our centre with encephalopathy, evaluated and found to have hyponatremia and hypokalemia rest of biochemical parameters and septic profile were normal. Patient's electrolyte disturbances were managed as per guidelines but encephalopathy persisted. Supportive treatment was continued and patient was discharged after 2 wks of stay in hospital after gaining full sensorium and neurological functions.

  6. Studies on osmotic concentration of radioactive effluents

    International Nuclear Information System (INIS)

    Thomas, K.C.; Ramachandhran, V.; Misra, B.M.

    1986-01-01

    The potential of direct osmosis for concentrating radioactive effluents is examined on the laboratory scale. Studies were carried out using asymmetric cellulose acetate membranes of a range of porosities under varying salinity gradients. A suitable bench scale osmotic concentrator employing tubular membrane systems has been fabricated and tested. An attempt to understand the mechanism of water permeation under osmotic and hydrostatic gradients has been made based on the irreversible thermodynamic approach. The solute separation of sodium chloride and radionuclides under osmosis is in the range of 85 to 95% for various osmotic sink solutions. The osmotic water flux is observed to be lower than the hydraulic water flux under reverse osmosis conditions. While the solute separation increases with an increase in annealing temperature, water flux decreases for both osmosis and reverse osmosis systems for various feed salinities. The effect of concentration polarization is analysed, and the effect of feed and osmotic sink velocity on the performance of the osmotic concentrator has also been studied. (orig.)

  7. Deionization shocks in flat and thin microchannels

    Science.gov (United States)

    Alizadeh, Shima; Andersen, Mathias B.; Mani, Ali

    2013-11-01

    We have investigated dynamics of deionization shocks in flat and thin microchannel using two different approaches: (1) extension of Mani and Bazant's simple model [PRE 2011] to two-dimensions, and (2) development of a height-averaged model from tabulated solutions of the Poisson-Boltzmann equation. The latter model is more accurate since it captures both thin and overlapped double-layer regimes as well as diffusion-osmotic flows. Both models describe ion transport and deionization shock dynamics in two dimensional space corresponding to the transverse flat dimensions. We compare prediction of these models for shock profile, speed and dynamical response, as well as onset conditions for hydrodynamic instability of deionization shocks. The outcome of this study has applications in deionization processes in lab-on-a-chip systems as well as porous microstructures.

  8. Pathogenic Free-Living Amoebae Isolated From Contact Lenses of Keratitis Patients.

    Science.gov (United States)

    Hajialilo, Elham; Niyyati, Maryam; Solaymani, Mohammad; Rezaeian, Mostafa

    2015-01-01

    Free-living amoeba (FLA)-related keratitis is a progressive infection of the cornea with poor prognosis. The present study aimed to investigates the contact lenses of patients with keratitis for pathogenic free-living amoebae. Overall, 62 contact lenses and their paraphernalia of patients with keratitis cultured and tested for the presence of free-living amoebae using morphological criteria. Unusual plates including plates containing mix amoebae and Vermamoeba were submitted to molecular analysis. Out of 62 plates, 11 revealed the outgrowth of free living amoeba of which 9 were Acanthamoeba, one plates contained mix amoebae including Acanthamoeba and Vermamoeba and one showed the presence of Vermamoeba. These two latter plates belonged to patients suffered from unilateral keratitis due to the misused of soft contact lenses. One of the patients had mix infection of Acanthamoeba (T4) and V. vermiformis meanwhile the other patient was infected with the V. vermiformis. Amoebic keratitis continues to rise in Iran and worldwide. To date, various genera of free-living amoebae such as Vermamoeba could be the causative agent of keratitis. Soft contact lens wearers are the most affected patients in the country, thus awareness of high-risk people for preventing free-living amoebae related keratitis is of utmost importance.

  9. Environmental Mycobacterium avium subsp. paratuberculosis Hosted by Free-Living Amoebae

    Directory of Open Access Journals (Sweden)

    Ascel Samba-Louaka

    2018-02-01

    Full Text Available Mycobacterium avium subsp. paratuberculosis is responsible for paratuberculosis in animals. This disease, leading to an inflammation of the gastrointestinal tract, has a high impact on animal health and an important economic burden. The environmental life cycle of M. avium subsp. paratuberculosis is poorly understood and several studies suggest that free-living amoebae (FLA might be a potential environmental host. FLA are protozoa found in water and soil that are described as reservoirs of pathogenic and non-pathogenic bacteria in the environment. Indeed, bacteria able to survive within these amoebae would survive phagocytosis from immune cells. In this study, we assessed the in vitro interactions between several strains of M. avium subsp. paratuberculosis and Acanthamoeba castellanii. The results indicate that the bacteria were able to grow within the amoeba and that they can survive for several days within their host. To explore the presence of M. avium subsp. paratuberculosis in environmental amoebae, we sampled water from farms positive for paratuberculosis. A M. avium subsp. paratuberculosis strain was detected within an environmental amoeba identified as related to the poorly described Rosculus genus. The bacterial strain was genotyped, showing that it was similar to previous infectious strains isolated from cattle. In conclusion, we described that various M. avium subsp. paratuberculosis strains were able to grow within amoebae and that these bacteria could be found on farm within amoebae isolated from the cattle environment. It validates that infected amoebae might be a reservoir and vector for the transmission of M. avium subsp. paratuberculosis.

  10. Pathogenic Free-Living Amoebae Isolated From Contact Lenses of Keratitis Patients

    Directory of Open Access Journals (Sweden)

    Elham HAJIALILO

    2015-12-01

    Full Text Available Background: Free-living amoeba (FLA-related keratitis is a progressive infection of the cornea with poor prognosis. The present study aimed to investigates the con­tact lenses of patients with keratitis for pathogenic free-living amoebae.Methods: Overall, 62 contact lenses and their paraphernalia of patients with kerati­tis cultured and tested for the presence of free-living amoebae using morphological criteria. Unusual plates including plates containing mix amoebae and Vermamoeba were submitted to molecular analysis. Results: Out of 62 plates, 11 revealed the outgrowth of free living amoeba of which 9 were Acanthamoeba, one plates contained mix amoebae including Acan­thamoeba and Vermamoeba and one showed the presence of Vermamoeba. These two latter plates belonged to patients suffered from unilateral keratitis due to the mis­used of soft contact lenses. One of the patients had mix infection of Acanthamoeba (T4 and V. vermiformis meanwhile the other patient was infected with the V. vermiformis. Conclusion: Amoebic keratitis continues to rise in Iran and worldwide. To date, various genera of free-living amoebae such as Vermamoeba could be the causative agent of keratitis. Soft contact lens wearers are the most affected patients in the country, thus awareness of high-risk people for preventing free-living amoebae re­lated keratitis is of utmost importance.

  11. Pathogenic amoebae in power-plant cooling lakes. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Tyndall, R.L.; Willaert, E.; Stevens, A.R.

    1981-06-01

    Cooling waters and associated algae and sediments from four northern and four southern/western electric power plants were tested for the presence of pathogenic amoebae. Unheated control waters and algae/sediments from four northern and five southern/western sites were also tested. When comparing results from the test versus control sites, a significantly higher proportion (P less than or equal to 0.05) of the samples from the test sites were positive for thermophilic amoeba, thermophilic Naegleria and pathogenic Naegleria. The difference in number of samples positive for thermophilic Naegleria between heated and unheated waters, however, was attributable predominantly to the northern waters and algae/sediments. While two of four northern test sites yielded pathogenic Naegleria, seven of the eight isolates were obtained from one site. Seasonality effects relative to the isolation of the pathogen were also noted at this site. One pathogen was isolated from a southwestern test site. Pathogens were not isolated from any control sites. Some of the pathogenic isolates were analyzed serologically and classified as pathogenic Naegleria fowleri. Salinity, pH, conductivity, and bacteriological profiles did not obviously correlate with the presence or absence of pathogenic Naegleria. While thermal addition was significantly associated with the presence of thermophilic Naegleria (P less than or equal to 0.05), the data implicate other as yet undefined parameters associated with the presence of the pathogenic thermophile. Until further delineation of these parameters is effected, generalizations cannot be made concerning the effect of thermal impact on the growth of pathogenic amoeba in a particular cooling system.

  12. Passive versus active local microrheology in mammalian cells and amoebae

    Science.gov (United States)

    Riviere, C.; Gazeau, F.; Marion, S.; Bacri, J.-C.; Wilhelm, C.

    2004-12-01

    We compare in this paper the rotational magnetic microrheology detailed by Marion et al [18] and Wilhelm et al [19] to the passive tracking microrheology. The rotational microrheology has been designed to explore, using magnetic rotating probes, the local intracellular microenvironment of living cells in terms of viscoelasticity. Passive microrheology techniques is based on the analysis of spontaneous diffusive motions of Brownian probes. The dependence of mean square displacement (MSD) with the time then directly reflects the type of movement (sub-, hyper- or diffusive motions). Using the same intracellular probes, we performed two types of measurements (active and passive). Based on the fluctuation-dissipation theorem, one should obtain the same information from the both techniques in a thermally equilibrium system. Interestingly, our measurements differ, and the discordances directly inform on active biological processes, which add to thermally activated fluctuations in our out-of equilibrium systems. In both cell models used, mammalian Hela cells and amoebae Entamoeba Histolytica, a hyper-diffusive regime at a short time is observed, which highlights the presence of an active non-thermal driving force, acting on the probe. However, the nature of this active force in mammalian cells and amoebae is different, according to their different phenotypes. In mammalian cells active processes are governed by the transport, via molecular motors, on the microtubule network. In amoebae, which are highly motile cells free of microtubule network, the active processes are dominated by strong fluxes of cytoplasm driven by extension of pseudopodia, in random directions, leading to an amplitude of motion one order of magnitude higher than for mammalian cells. Figs 7, Refs 32.

  13. Inverse osmotic process for radioactive laundry waste

    International Nuclear Information System (INIS)

    Ebara, Katsuya; Takahashi, Sankichi; Sugimoto, Yoshikazu; Yusa, Hideo; Hyakutake, Hiroshi.

    1977-01-01

    Purpose: To effectively recover the processing amount reduced in a continuous treatment. Method: Laundry waste containing radioactive substances discharged from a nuclear power plant is processed in an inverse osmotic process while adding starch digesting enzymes such as amylase and takadiastase, as well as soft spherical bodies such as sponge balls of a particle diameter capable of flowing in the flow of the liquid wastes along the inverse osmotic membrane pipe and having such a softness and roundness as not to damage the inverse osmotic membrane. This process can remove the floating materials such as thread dusts or hairs deposited on the membrane surface by the action of the soft elastic balls and remove paste or the like through decomposition by the digesting enzymes. Consequently, effective recovery can be attained for the reduced processing amount. (Furukawa, Y.)

  14. New Osmosis Law and Theory: the New Formula that Replaces van't Hoff Osmotic Pressure Equation

    OpenAIRE

    Huang, Hung-Chung; Xie, Rongqing

    2012-01-01

    This article derived a new abstract concept from the osmotic process and concluded it via "osmotic force" with a new law -- "osmotic law". The "osmotic law" describes that, in an osmotic system, osmolyte moves osmotically from the side with higher "osmotic force" to the side with lower "osmotic force". In addition, it was proved mathematically that the osmotic process could be explained perfectly via "osmotic force" and "osmotic laws", which can prevent the difficulties in using current "osmo...

  15. [Amoebas of the genus acanthamoeba as an etiological factor of keratitis].

    Science.gov (United States)

    Kosik-Bogacka, Danuta; Czepita, Damian; Łanocha, Natalia

    2010-01-01

    The aim of the paper was to describe the role of amoebas of the genus Acanthamoeba in the pathogenesis of keratitis. A review of literature concerning the role of amoebas of the genus Acanthamoeba in the pathogenesis of keratitis was done. Amoebas of the genus Acanthamoeba can be widely found in soil, air, fresh as well as saline water and as facultative parasites in humans. Amoebas of this genus are responsible for the creation of Acanthamoeba keratitis. In this paper the latest data concerning the epidemiology, diagnostic and treatment of Acanthamoeba keratitis have been cited and disscused. 1. Keratitis induced by amoebas of the genus Acanthamoeba are characterized as acute and difficult to treat. 2. Acanthamoeba keratitis occurs in recent years more often due to the fact that more people wear contact lenses.

  16. Global analysis of the yeast osmotic stress response by quantitative proteomics

    DEFF Research Database (Denmark)

    Soufi, Boumediene; Kelstrup, C.D.; Stoehr, G.

    2009-01-01

    used for glycerol production that is up-regulated to counterbalance the increased osmolarity of the salt containing growth medium. Although the overall relationship between our proteome and published mRNA changes is poor we find an excellent correlation between the subset of osmotic shock up......Information on extracellular signals and conditions is often transduced by biological systems using cascades of protein phosphorylation that affect the activity of enzymes, the localization of proteins and gene expression. A model to study signal transduction is the response of the yeast...... a comprehensive, quantitative, and time-resolved analysis using high-resolution mass spectrometry of phospho-proteome and proteome changes in response to osmotic stress in yeast. We identified 5534 unique phosphopeptide variants and 3383 yeast proteins. More than 15% of the detected phosphorylation site status...

  17. Osmotic dehydration of fish: principal component analysis

    Directory of Open Access Journals (Sweden)

    Lončar Biljana Lj.

    2014-01-01

    Full Text Available Osmotic treatment of the fish Carassius gibelio was studied in two osmotic solutions: ternary aqueous solution - S1, and sugar beet molasses - S2, at three solution temperatures of 10, 20 and 30oC, at atmospheric pressure. The aim was to examine the influence of type and concentration of the used hypertonic agent, temperature and immersion time on the water loss, solid gain, dry mater content, aw and content of minerals (Na, K, Ca and Mg. S2 solution has proven to be the best option according to all output variables.[ Projekat Ministarstva nauke Republike Srbije, br. TR 31055

  18. Dependence of osmotic pressure on solution properties

    International Nuclear Information System (INIS)

    Fritz, S.J.

    1978-01-01

    Hydrostatic pressure, temperature, salt concentration, and the chemical composition of the salt are parameters affecting solution properties. Pressure and temperature have little effect on osmosis, but osmotic pressure variations due to type of dissolved salt may be significant, especially at high concentrations. For a given salt solution, concentration variations cause large differences in osmotic pressure. A representative difference in concentration across a clay layer in a relatively shallow groundwater system might be 100 to 1,000 ppm. When expressed as ppm NaCl, this difference could cause a head difference of 0.8 to 8 meters of water if one of the rock bodies were closed to fluid escape

  19. Electro-osmotic pumping of sodium chloride solutions

    CSIR Research Space (South Africa)

    Schoeman, JJ

    1997-08-20

    Full Text Available Electro-osmotic pumping (EOP) theory and its characteristics (transport numbers, brine concentration, current density, current efficiency, electro-osmotic coefficients, etc.) of Selemion AMV and CMV ion-exchange membranes were studied. The brine...

  20. Increased Resistance to osmotic lysis of sickled erythrocytes ...

    African Journals Online (AJOL)

    treated with CNw had significantly reduced osmotic lysis when compared with the untreated set (P<0.05, respectively) at various hypotonic NaCl concentrations. Various Hb genotypes exhibited a graded increase in osmotic pressure lysis in ...

  1. Release Mechanism Between Ion Osmotic Pressure and Drug Release in Ionic-Driven Osmotic Pump Tablets (I).

    Science.gov (United States)

    Cheng, Lizhen; Gao, Siqi; Ouyang, Defang; Wang, Haiying; Wang, Yongfei; Pan, Weisan; Yang, Xinggang

    2018-02-01

    The objective of this study was to develop an authentic ionic-driven osmotic pump system and investigate the release mechanism, simultaneously exploring the in vitro and in vivo correlation of the ionic-driven osmotic pump tablet. A comparison of the ionic-driven and conventional theophylline osmotic pump, the influence of pH and the amount of sodium chloride on drug release, the relationship between the ionic osmotic pressure and the drug release, and the pharmacokinetics experiment in beagle dogs were investigated. Consequently, the similarity factor (f 2 ) between the novel and conventional theophylline osmotic pump tablet was 60.18, which indicated a similar drug-release behavior. Also, the release profile fitted a zero-order kinetic model. The relative bioavailability of the ionic-driven osmotic pump to the conventional osmotic pump calculated from the AUC (0-∞) was 93.6% and the coefficient (R = 0.9945) confirmed that the ionic-driven osmotic pump exhibited excellent IVIVC. The driving power of the ionic-driven osmotic pump was produced only by ions, which was strongly dependent on the ion strength, and a novel formula for the ionic-driven osmotic pump was derived which indicated that the drug-release rate was proportional to the ionic osmotic pressure and the sodium chloride concentration. Significantly, the formula can predict the drug-release rate and release characteristics of theophylline ionic-driven osmotic pumps, guiding future modification of the ionic osmotic pump.

  2. Changes in Hematological Parameters and Erythrocyte Osmotic ...

    African Journals Online (AJOL)

    The study was aimed at evaluating the changes in haematological parameters and erythrocyte osmotic fragility in lame and aged horses administered with resveratrol supplement (Equithrive joint®). A total of 16 horses of both sexes, aged 18 ± 0.65 and showing lameness grade 3 were used for the study. The horses ...

  3. Comparative Erythrocytes Osmotic Fragility Test and some ...

    African Journals Online (AJOL)

    Erythrocytes osmotic fragility and haematological parameters of subjects with HbAS (sickle cell trait) and HbSS (sickle cell anaemia) were determined and compared with subjects with HbAA (normal adult haemoglobin), which acted as control. They were divided into three groups of 40 subjects for HbAA, 35 subjects for ...

  4. Free Living Amoeba Belonging to Vannella Spp. Isolated from a Hotspring in Amol City, Northern Iran

    Directory of Open Access Journals (Sweden)

    Maryam Niyyati

    2017-04-01

    Full Text Available Background: Free-living amoebae have various genera that are found in several environmental niches such as soil, freshwater, dust, seawater and hotsprings. Most of Free-living amoebae are normally harmless to humans. However, some ameoba such as Acanthamoeba and also Naegleria fowleri, Balamuthia manderillaris and Sappinia are identified as opportunistic and pathogenic amoebae that can cause eye diseases, encephalitis, and meningoencephalitis in human. Vannellidae are a family of free-living amoebae and exist mainly in soil, freshwater, and marine habitats. This amoeba is nonpathogenic for human, but can act as a Trojan horse for other pathogens such as Microsporidia. The present study reports the occurrence of Vannella spp. in a hotspring of Amol city.Materials and Methods: 22 samples were taken from hotsprings of Mazandaran province during our previous study. The plates were checked for the presence of Vannella spp. according to the specific morphological criteria. DNA extraction, PCR and sequencing was performed on the positive isolate.Results: The result showed that one plate contained fan-shaped amoebae suspected to Vannella spp. PCR analysis and sequencing was confirmed the occurrence of Vannella spp. in one sample of a hot spring of Amol, northern Iran.Conclusion: The result confirmed the presence of Vannella amoebae in the hotspring of Amol city. More studies are needed to clarify the real distribution of Vannella spp. in environmental niches and its pathogenic potential in Iran and worldwide.

  5. SPATIAL-VARIANT MORPHOLOGICAL FILTERS WITH NONLOCAL-PATCH-DISTANCE-BASED AMOEBA KERNEL FOR IMAGE DENOISING

    Directory of Open Access Journals (Sweden)

    Shuo Yang

    2015-01-01

    Full Text Available Filters of the Spatial-Variant amoeba morphology can preserve edges better, but with too much noise being left. For better denoising, this paper presents a new method to generate structuring elements for Spatially-Variant amoeba morphology.  The amoeba kernel in the proposed strategy is divided into two parts: one is the patch distance based amoeba center, and another is the geodesic distance based amoeba boundary, by which the nonlocal patch distance and local geodesic distance are both taken into consideration. Compared to traditional amoeba kernel, the new one has more stable center and its shape can be less influenced by noise in pilot image. What’s more important is that the nonlocal processing approach can induce a couple of adjoint dilation and erosion, and combinations of them can construct adaptive opening, closing, alternating sequential filters, etc. By designing the new amoeba kernel, a family of morphological filters therefore is derived. Finally, this paper presents a series of results on both synthetic and real images along with comparisons with current state-of-the-art techniques, including novel applications to medical image processing and noisy SAR image restoration.

  6. Detection and Identification of Free-living Amoeba from Environmental Water in Taiwan by PCR Method

    Science.gov (United States)

    Tsai, H. F.; Hsu, B. M.; Huang, K. H.; She, C. Y.; Kao, P. M.; Shen, S. M.; Tseng, S. F.; Chen, J. S.

    2012-04-01

    Acanthamoeba, Naegleria, Balamuthia and Hartmannella all belong to free-living amoebae that are present ubiquitously in the environment including water, soil, and air. Free-living amoebae are parasites which can infect humans and can lead to serious illness and even death. The aim of this study is to investigate the presence of free-living amoebae in aquatic environment in Taiwan, and to compare the differences between Acanthamoeba and Naegleria in diverse cultivation methods and conditions. In this study, we used molecular method by PCR amplification with specific primers to analyze the occurrence of free-living amoebae. We collected 176 samples from environmental water including drinking water treatment plants, stream water, and hot spring recreational areas in Taiwan. Based on the results of PCR, 43 water samples (24.4%) were detected positive for free-living amoebae. The most common Acanthamoeba genotype isolated from samples including T2, T4, T5, T12, and T15. N. australiensis and N. lovaniensis were also identified by molecular biology techniques. Furthermore, we found that both Acanthamoeba and Naegleria can be cultured by PYG in 30° C, but not all free-living amoebae can be isolated and enriched by using storage-cultivation method. Because of the widespread presence of Acanthamoeba and Naegleria in aquatic environments, the water quality and safety of aquatic environments should be more conscious in Taiwan and worldwide. Keywords: free-living amoebae; Acanthamoeba; Naegleria; Balamuthia; Hartmannella; PCR

  7. demystifying the shock of shocking

    African Journals Online (AJOL)

    demystifying the shock of shocking. Beyra Rossouw, MB ChB, MMed. (Paed), DTM, MSc (Sports Medicine),. Certificate Critical Care (Paed). Senior Registrar Paediatric Cardiology, Western. Cape Paediatric Cardiac Services, Red Cross. War Memorial Children's Hospital, University of. Cape Town, and Tygerberg Children's ...

  8. Genetic Variation in the Free-Living Amoeba Naegleria fowleri

    Science.gov (United States)

    Pélandakis, Michel; De Jonckheere, Johan F.; Pernin, Pierre

    1998-01-01

    In this study, 30 strains of the pathogenic free-living amoeba Naegleria fowleri were investigated by using the randomly amplified polymorphic DNA (RAPD) method. The present study confirmed our previous finding that RAPD variation is not correlated with geographical origin. In particular, Mexican strains belong to the variant previously detected in Asia, Europe, and the United States. In France, surprisingly, strains from Cattenom gave RAPD patterns identical to those of the Japanese strains. In addition, all of these strains, together with an additional French strain from Chooz, exhibited similarities to South Pacific strains. The results also confirmed the presence of numerous variants in Europe, whereas only two variants were detected in the United States. The two variants found in the United States were different from the South Pacific variants. These findings do not support the previous hypothesis concerning the origin and modes of dispersal of N. fowleri. PMID:9687460

  9. Fast, multiphase volume adaptation to hyperosmotic shock by Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Teuta Pilizota

    Full Text Available All living cells employ an array of different mechanisms to help them survive changes in extra cellular osmotic pressure. The difference in the concentration of chemicals in a bacterium's cytoplasm and the external environment generates an osmotic pressure that inflates the cell. It is thought that the bacterium Escherichia coli use a number of interconnected systems to adapt to changes in external pressure, allowing them to maintain turgor and live in surroundings that range more than two-hundred-fold in external osmolality. Here, we use fluorescence imaging to make the first measurements of cell volume changes over time during hyperosmotic shock and subsequent adaptation on a single cell level in vivo with a time resolution on the order of seconds. We directly observe two previously unseen phases of the cytoplasmic water efflux upon hyperosmotic shock. Furthermore, we monitor cell volume changes during the post-shock recovery and observe a two-phase response that depends on the shock magnitude. The initial phase of recovery is fast, on the order of 15-20 min and shows little cell-to-cell variation. For large sucrose shocks, a secondary phase that lasts several hours adds to the recovery. We find that cells are able to recover fully from shocks as high as 1 Osmol/kg using existing systems, but that for larger shocks, protein synthesis is required for full recovery.

  10. Cardiogenic shock

    Science.gov (United States)

    ... occur during or after a heart attack (myocardial infarction). These complications include: A large section of heart ... high blood pressure, high cholesterol and triglycerides, or tobacco use Alternative Names Shock - cardiogenic Images Heart, section ...

  11. Osmotic consolidation of suspensions and gels

    International Nuclear Information System (INIS)

    Miller, K.T.; Zukoski, C.F.

    1994-01-01

    An osmotic method for the consolidation of suspensions of ceramic particles is demonstrated. Concentrated solutions of poly(ethylene oxide) are separated from a suspension of ceramic particles by a semipermeable membrane, creating a gradient in solvent chemical potential. Solvent passes from the suspension into the polymer solution, lowering its free energy and consolidating the suspension. Dispersions of stable 8-nm hydrous zirconia particles were consolidated to over 47% by volume. Suspensions of α-alumina in three states of aggregation (dispersed, weakly flocculated, and strongly flocculated) were consolidated to densities greater than or equal to those produced in conventional pressure filtration. Moreover, the as-consolidated alumina bodies were partially drained of fluid during the osmotic consolidation process, producing cohesive partially dried bodies with improved handling characteristics

  12. Shock absorber

    International Nuclear Information System (INIS)

    Housman, J.J.

    1978-01-01

    A shock absorber is described for use in a hostile environment at the end of a blind passage for absorbing impact loads. The shock absorber includes at least one element which occupies the passage and which is comprised of a porous brittle material which is substantially non-degradable in the hostile environment. A void volume is provided in the element to enable the element to absorb a predetermined level of energy upon being crushed due to impact loading

  13. The pore forming capacity of Sticholysin I in dipalmitoyl phosphatidyl vesicles is tuned by osmotic stress.

    Science.gov (United States)

    Ahumada, M; Calderon, C; Lissi, E; Alvarez, C; Lanio, M E; Pazos, F

    2017-03-01

    The osmotic condition modulates the properties of liposomes, particularly those related to their stability and response to external agents such as membrane-active proteins or peptides. In a previous work, we have demonstrated that an osmotic shock can increase, per se, water influx/efflux and the exit of the fluorophore calcein entrapped in the aqueous pool of dipalmitoylphosphatidylcholine (DPPC) and DPPC:sphingomyelin (SM) large unilamellar vesicles (LUVs), suggesting a loss of integrity of the liposome bilayer. In the present work, we have extended our study in order to assess how an osmotic imbalance prior to or synchronous with the addition of a recombinant variant of the pore-forming toxin sticholysin I (rSt I) modifies its pore forming capacity in DPPC and DPPC:SM (1:1) LUVs. Our results conclusively show the capacity of hypotonic gradients to improve the pore forming capacity of rSt I molecules, even in pure DPPC liposomes, rendering pore-formation less dependent on the presence of sphyngomyelin. In fact, non-active toxins in DPPC liposomes become active by a hypotonic imbalance in a similar way to those containing SM as a second component. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Osmotically-assisted desalination method and system

    Science.gov (United States)

    Achilli, Andrea; Childress, Amy E.; Cath, Tzahi Y.

    2014-08-12

    Systems and methods for osmotically assisted desalination include using a pressurized concentrate from a pressure desalination process to pressurize a feed to the desalination process. The depressurized concentrate thereby produced is used as a draw solution for a pressure-retarded osmosis process. The pressure-retarded osmosis unit produces a pressurized draw solution stream that is used to pressurize another feed to the desalination process. In one example, the feed to the pressure-retarded osmosis process is impaired water.

  15. A REVIEW ON OSMOTIC DRUG DELIVERY SYSTEM

    OpenAIRE

    Harnish Patel; Upendra Patel; Hiren Kadikar; Bhavin Bhimani; Dhiren Daslaniya; Ghanshyam Patel

    2012-01-01

    Conventional oral drug delivery systems supply an instantaneous release of drug, which cannot control the release of the drug and effective concentration at the target site. This kind of dosing pattern may result in constantly changing, unpredictable plasma concentrations. Drugs can be delivered in a controlled pattern over a long period of time by the process of osmosis. Osmotic devices are the most promising strategy based systems for controlled drug delivery. They are the most reliable con...

  16. Contrasting species-environment relationships in communities of testate amoebae, bryophytes and vascular plants along the fen-bog gradient.

    Science.gov (United States)

    Lamentowicz, Mariusz; Lamentowicz, Lukasz; van der Knaap, Willem O; Gabka, Maciej; Mitchell, Edward A D

    2010-04-01

    We studied the vegetation, testate amoebae and abiotic variables (depth of the water table, pH, electrical conductivity, Ca and Mg concentrations of water extracted from mosses) along the bog to extremely rich fen gradient in sub-alpine peatlands of the Upper Engadine (Swiss Alps). Testate amoeba diversity was correlated to that of mosses but not of vascular plants. Diversity peaked in rich fen for testate amoebae and in extremely rich fen for mosses, while for testate amoebae and mosses it was lowest in bog but for vascular plants in extremely rich fen. Multiple factor and redundancy analyses (RDA) revealed a stronger correlation of testate amoebae than of vegetation to water table and hydrochemical variables and relatively strong correlation between testate amoeba and moss community data. In RDA, hydrochemical variables explained a higher proportion of the testate amoeba and moss data than water table depth. Abiotic variables explained a higher percentage of the species data for testate amoebae (30.3% or 19.5% for binary data) than for mosses (13.4%) and vascular plants (10%). These results show that (1) vascular plant, moss and testate amoeba communities respond differently to ecological gradients in peatlands and (2) testate amoebae are more strongly related than vascular plants to the abiotic factors at the mire surface. These differences are related to vertical trophic gradients and associated niche differentiation.

  17. The gene cutA of Fusarium fujikuroi, encoding a protein of the haloacid dehalogenase family, is involved in osmotic stress and glycerol metabolism.

    Science.gov (United States)

    García-Martínez, Jorge; Castrillo, Marta; Avalos, Javier

    2014-01-01

    Survival of micro-organisms in natural habitats depends on their ability to adapt to variations in osmotic conditions. We previously described the gene cut-1 of Neurospora crassa, encoding a protein of the haloacid dehalogenase family with an unknown function in the osmotic stress response. Here we report on the functional analysis of cutA, the orthologous gene in the phytopathogenic fungus Fusarium fujikuroi. cutA mRNA levels increased transiently after exposure to 0.68 M NaCl and were reduced upon return to normal osmotic conditions; deletion of the gene resulted in a partial reduction in tolerance to osmotic stress. ΔcutA mutants contained much lower intracellular levels of glycerol than the wild-type, and did not exhibit the increase following hyper-osmotic shock expected from the high osmolarity glycerol (HOG) response. cutA is linked and divergently transcribed with the putative glycerol dehydrogenase gene gldB, which showed the same regulation by osmotic shock. The intergenic cutA/gldB regulatory region contains putative stress-response elements conserved in other fungi, and both genes shared other regulatory features, such as induction by heat shock and by illumination. Photoinduction was also observed in the HOG response gene hogA, and was lost in mutants of the white collar gene wcoA. Previous data on glycerol production in Aspergillus spp. and features of the predicted CutA protein lead us to propose that F. fujikuroi produces glycerol from dihydroxyacetone, and that CutA is the enzyme involved in the synthesis of this precursor by dephosphorylation of dihydroxyacetone-3P.

  18. Hydrothermal Carbonization of Spent Osmotic Solution (SOS Generated from Osmotic Dehydration of Blueberries

    Directory of Open Access Journals (Sweden)

    Kaushlendra Singh

    2014-09-01

    Full Text Available Hydrothermal carbonization of spent osmotic solution (SOS, a waste generated from osmotic dehydration of fruits, has the potential of transformation into hydrochars, a value-added product, while reducing cost and overall greenhouse gas emissions associated with waste disposal. Osmotic solution (OS and spent osmotic solution (SOS generated from the osmotic dehydration of blueberries were compared for their thermo-chemical decomposition behavior and hydrothermal carbonization. OS and SOS samples were characterized for total solids, elemental composition, and thermo-gravimetric analysis (TGA. In addition, hydrothermal carbonization was performed at 250 °C and for 30 min to produce hydrochars. The hydrochars were characterized for elemental composition, Brunauer-Emmett-Teller (BET surface area, particle shape and surface morphology. TGA results show that the SOS sample loses more weight in the lower temperature range than the OS sample. Both samples produced, approximately, 40%–42% (wet-feed basis hydrochar during hydrothermal carbonization but with different properties. The OS sample produced hydrochar, which had spherical particles of 1.79 ± 1.30 μm diameter with a very smooth surface. In contrast, the SOS sample produced hydrochar with no definite particle shape but with a raspberry-like surface.

  19. Electro-osmotic flows inside triangular microchannels

    International Nuclear Information System (INIS)

    Vocale, P; Spiga, M; Geri, M; Morini, G L

    2014-01-01

    This work presents a numerical investigation of both pure electro-osmotic and combined electro-osmotic/pressure-driven flows inside triangular microchannels. A finite element analysis has been adopted to solve the governing equations for the electric potential and the velocity field, accounting for a finite thickness of the electric double layer. The influence of non-dimensional parameters such as the aspect ratio of the cross-section, the electrokinetic diameter and the ratio of the pressure force to the electric force on the flow behavior has been investigated. Numerical results point out that the velocity field is significantly influenced by the aspect ratio of the cross section and the electrokinetic diameter. More specifically, the aspect ratio plays an important role in determining the maximum volumetric flow rate, while the electrokinetic diameter is crucial to establishing the range of pressures that may be sustained by the electro-osmotic flow. Numerical results are also compared with two correlations available in the literature which enable to assess the volumetric flow rate and the pressure head for microchannels featuring a rectangular, a trapezoidal or an elliptical cross-section.

  20. Diversity and distribution of freshwater testate amoebae (protozoa) along latitudinal and trophic gradients in China.

    Science.gov (United States)

    Ju, Lihua; Yang, Jun; Liu, Lemian; Wilkinson, David M

    2014-11-01

    Freshwater microbial diversity is subject to multiple stressors in the Anthropocene epoch. However, the effects of climate changes and human activities on freshwater protozoa remain poorly understood. In this study, the diversity and distribution of testate amoebae from the surface sediments were investigated in 51 Chinese lakes and reservoirs along two gradients, latitude and trophic status. A total of 169 taxa belonging to 24 genera were identified, and the most diverse and dominant genera were Difflugia (78 taxa), Centropyxis (26 taxa) and Arcella (12 taxa). Our analysis revealed that biomass of testate amoebae decreased significantly along the latitudinal gradient, while Shannon-Wiener indices and species richness presented an opposite trend (P trophic status (P trophic status on diversity and distribution of testate amoebae in China. Therefore, our results provide valuable baseline data on testate amoebae and contribute to lake management and our understanding of the large-scale global patterns in microorganism diversity.

  1. Intra-amoeba multiplication induces chemotaxis and biofilm colonization and formation for Legionella.

    Directory of Open Access Journals (Sweden)

    Renaud Bigot

    Full Text Available Legionella pneumophila, a facultative intracellular bacterium, is the causative agent of legionellosis. In the environment this pathogenic bacterium colonizes the biofilms as well as amoebae, which provide a rich environment for the replication of Legionella. When seeded on pre-formed biofilms, L. pneumophila was able to establish and survive and was only found at the surface of the biofilms. Different phenotypes were observed when the L. pneumophila, used to implement pre-formed biofilms or to form mono-species biofilms, were cultivated in a laboratory culture broth or had grown intracellulary within the amoeba. Indeed, the bacteria, which developed within the amoeba, formed clusters when deposited on a solid surface. Moreover, our results demonstrate that multiplication inside the amoeba increased the capacity of L. pneumophila to produce polysaccharides and therefore enhanced its capacity to establish biofilms. Finally, it was shown that the clusters formed by L. pneumophila were probably related to the secretion of a chemotaxis molecular agent.

  2. Free-living amoebae in sediments from the Lascaux Cave in France.

    Directory of Open Access Journals (Sweden)

    Garcia-Sanchez A.M.

    2013-01-01

    Full Text Available The Lascaux Cave in France is an old karstic channel where the running waters are collected in a pool and pumped to the exterior. It is well-known that water bodies in the vicinity of humans are suspected to be reservoirs of amoebae and associated bacteria. In fact, the free-living amoebae Acanthamoeba astronyxis, Acanthamoeba castellanii, Acanthamoeba sp. and Hartmannella vermiformis were identif ied in the sediments of the cave using phylogenetic analyses and morphological traits. Lascaux Cave sediments and rock walls are wet due to a relative humidity near saturation and water condensation, and this environment and the presence of abundant bacterial communities constitute an ideal habitat for amoebae. The data suggest the need to carry out a detailed survey on all the cave compartments in order to determine the relationship between amoebae and pathogenic bacteria.

  3. Detection of Free-Living Amoebae in Some Water Sources and its Control by Ultraviolet- Radiation

    International Nuclear Information System (INIS)

    Moawed, M.A.F.; Shihab, A.

    2000-01-01

    Among the numerous free-living amoebae (FLA) of soil and water habitats, certain species belonging to two genera Acanthamoeba and Naegleria are facultative parasites of man.They cause disease called primary amoebic meningoencephalitis where history of contact with water was recorded in most of the cases especially with Naegleria species. The present work aimed to search for presence of free-living amoebae in the water and trials for its control by Ultraviolet-radiation (UV-radiation). Samples from different water sources were examined for the presence of free-living amoebae. These samples were cultured on non-nutrient agar streaked with bacteria. Amoebae were detected and identified by means of their morphological characters. Twelve positive cases of one hundred and twenty examined samples could be detected. The positive samples were exposed to different doses of UV-radiation for different times

  4. Divalent Metal Cations Potentiate the Predatory Capacity of Amoeba for Cryptococcus neoformans.

    Science.gov (United States)

    Fu, Man Shun; Casadevall, Arturo

    2018-02-01

    Among the best-studied interactions between soil phagocytic predators and a human-pathogenic fungus is that of Acanthamoeba castellanii and Cryptococcus neoformans The experimental conditions used in amoeba-fungus confrontation assays can have major effects on whether the fungus or the protozoan is ascendant in the interaction. In the presence of Mg 2+ and Ca 2+ in phosphate-buffered saline (PBS), C. neoformans was consistently killed when incubated with A. castellanii A. castellanii survived better in the presence of Mg 2+ and Ca 2+ , even when incubated with C. neoformans In the absence of Mg 2+ and Ca 2+ , C. neoformans survived when incubated with A. castellanii , and the percentage of dead amoebae was higher than when incubated without yeast cells. These results show that the presence of Mg 2+ and Ca 2+ can make a decisive contribution toward tilting the outcome of the interaction in favor of the amoeba. Of the two metals, Mg 2+ had a stronger effect than Ca 2+ The cations enhanced A. castellanii activity against C. neoformans via enhanced phagocytosis, which is the major mechanism by which amoebae kill fungal cells. We found no evidence that amoebae use extracellular killing mechanisms in their interactions with C. neoformans In summary, the presence of Mg 2+ and Ca 2+ enhanced the cell adhesion on the surfaces and the motility of the amoeba, thus increasing the chance for contact with C. neoformans and the frequency of phagocytosis. Our findings imply that the divalent cation concentration in soils could be an important variable for whether amoebae can control C. neoformans in the environment. IMPORTANCE The grazing of soil organisms by phagocytic predators such as amoebae is thought to select for traits that enable some of them to acquire the capacity for virulence in animals. Consequently, knowledge about the interactions between amoebae and soil microbes, such as pathogenic fungi, is important for understanding how virulence can emerge. We show that the

  5. Amoeba-related health risk in drinking water systems: could monitoring of amoebae be a complementary approach to current quality control strategies?

    Science.gov (United States)

    Codony, Francesc; Pérez, Leonardo Martín; Adrados, Bárbara; Agustí, Gemma; Fittipaldi, Mariana; Morató, Jordi

    2012-01-01

    Culture-based methods for fecal indicator microorganisms are the standard protocol to assess potential health risk from drinking water systems. However, these traditional fecal indicators are inappropriate surrogates for disinfection-resistant fecal pathogens and the indigenous pathogens that grow in drinking water systems. There is now a range of molecular-based methods, such as quantitative PCR, which allow detection of a variety of pathogens and alternative indicators. Hence, in addition to targeting total Escherichia coli (i.e., dead and alive) for the detection of fecal pollution, various amoebae may be suitable to indicate the potential presence of pathogenic amoeba-resisting microorganisms, such as Legionellae. Therefore, monitoring amoeba levels by quantitative PCR could be a useful tool for directly and indirectly evaluating health risk and could also be a complementary approach to current microbial quality control strategies for drinking water systems.

  6. Survival and growth of Stenotrophomonas maltophilia in free-living amoebae (FLA) and bacterial virulence properties.

    Science.gov (United States)

    Denet, Elodie; Vasselon, Valentin; Burdin, Béatrice; Nazaret, Sylvie; Favre-Bonté, Sabine

    2018-01-01

    Stenotrophomonas maltophilia is found ubiquitously in the environment and is an important emerging nosocomial pathogen. S. maltophilia has been recently described as an Amoebae-Resistant Bacteria (ARB) that exists as part of the microbiome of various free-living amoebae (FLA) from waters. Co-culture approaches with Vermamoeba vermiformis demonstrated the ability of this bacterium to resist amoebal digestion. In the present study, we assessed the survival and growth of six environmental and one clinical S. maltophilia strains within two amoebal species: Acanthamoeba castellanii and Willaertia magna. We also evaluated bacterial virulence properties using the social amoeba Dictyostelium discoideum. A co-culture approach was carried out over 96 hours and the abundance of S. maltophilia cells was measured using quantitative PCR and culture approach. The presence of bacteria inside the amoeba was confirmed using confocal microscopy. Our results showed that some S. maltophilia strains were able to multiply within both amoebae and exhibited multiplication rates up to 17.5 and 1166 for A. castellanii and W. magna, respectively. In contrast, some strains were unable to multiply in either amoeba. Out of the six environmental S. maltophilia strains tested, one was found to be virulent. Surprisingly, this strain previously isolated from a soil amoeba, Micriamoeba, was unable to infect both amoebal species tested. We further performed an assay with a mutant strain of S. maltophilia BurA1 lacking the efflux pump ebyCAB gene and found the mutant to be more virulent and more efficient for intra-amoebal multiplication. Overall, the results obtained strongly indicated that free-living amoebae could be an important ecological niche for S. maltophilia.

  7. Survival and growth of Stenotrophomonas maltophilia in free-living amoebae (FLA and bacterial virulence properties.

    Directory of Open Access Journals (Sweden)

    Elodie Denet

    Full Text Available Stenotrophomonas maltophilia is found ubiquitously in the environment and is an important emerging nosocomial pathogen. S. maltophilia has been recently described as an Amoebae-Resistant Bacteria (ARB that exists as part of the microbiome of various free-living amoebae (FLA from waters. Co-culture approaches with Vermamoeba vermiformis demonstrated the ability of this bacterium to resist amoebal digestion. In the present study, we assessed the survival and growth of six environmental and one clinical S. maltophilia strains within two amoebal species: Acanthamoeba castellanii and Willaertia magna. We also evaluated bacterial virulence properties using the social amoeba Dictyostelium discoideum. A co-culture approach was carried out over 96 hours and the abundance of S. maltophilia cells was measured using quantitative PCR and culture approach. The presence of bacteria inside the amoeba was confirmed using confocal microscopy. Our results showed that some S. maltophilia strains were able to multiply within both amoebae and exhibited multiplication rates up to 17.5 and 1166 for A. castellanii and W. magna, respectively. In contrast, some strains were unable to multiply in either amoeba. Out of the six environmental S. maltophilia strains tested, one was found to be virulent. Surprisingly, this strain previously isolated from a soil amoeba, Micriamoeba, was unable to infect both amoebal species tested. We further performed an assay with a mutant strain of S. maltophilia BurA1 lacking the efflux pump ebyCAB gene and found the mutant to be more virulent and more efficient for intra-amoebal multiplication. Overall, the results obtained strongly indicated that free-living amoebae could be an important ecological niche for S. maltophilia.

  8. Dynamics of hybrid amoeba proteus containing zoochlorellae studied using fluorescence spectroscopy

    Science.gov (United States)

    Liu, C.-H.; Fong, B. A.; Alfano, S. A., Jr.; Rakhlin, I.; Wang, W. B.; Ni, X. H.; Yang, Y. L.; Zhou, F.; Zuzolo, R. C.; Alfano, R. R.

    2011-03-01

    The microinjection of organelles, plants, particles or chemical solutions into Amoeba proteus coupled with spectroscopic analysis and observed for a period of time provides a unique new model for cancer treatment and studies. The amoeba is a eukaryote having many similar features of mammalian cells. The amoeba biochemical functions monitored spectroscopically can provide time sequence in vivo information about many metabolic transitions and metabolic exchanges between cellar organelles and substances microinjected into the amoeba. It is possible to microinject algae, plant mitochondria, drugs or carcinogenic solutions followed by recording the native fluorescence spectra of these composites. This model can be used to spectroscopically monitor the pre-metabolic transitions in developing diseased cells such as a cancer. Knowing specific metabolic transitions could offer solutions to inhibit cancer or reverse it as well as many other diseases. In the present study a simple experiment was designed to test the feasibility of this unique new model by injecting algae and chloroplasts into amoeba. The nonradiative dynamics found from these composites are evidence in terms of the emission ratios between the intensities at 337nm and 419nm; and 684nm bands. There were reductions in the metabolic and photosynthetic processes in amoebae that were microinjected with chloroplasts and zoochlorellae as well of those amoebae that ingested the algae and chloroplasts. The changes in the intensity of the emissions of the peaks indicate that the zoochlorellae lived in the amoebae for ten days. Spectral changes in intensity under the UV and 633nm wavelength excitation are from the energy transfer of DNA and RNA, protein-bound chromophores and chlorophylls present in zoochlorellae undergoing photosynthesis. The fluorescence spectroscopic probes established the biochemical interplay between the cell organelles and the algae present in the cell cytoplasm. This hybrid state is indicative

  9. Diversity and community ecology of forest epiphyte testate amoebae from European Russia.

    Science.gov (United States)

    Payne, Richard J; Belyakova, Olga; Mazei, Yuri

    2015-10-01

    Testate amoebae are an abundant group of microorganisms which make a significant contribution to the diversity of protist life. Most of the world's potential habitats for testate amoebae have been barely studied and when such places are investigated they frequently reveal novel communities and species. Here we consider the testate amoeba communities associated with boreal forest epiphytes (mosses and lichens); an environment which we argue has been under-researched. We present a dataset of 165 samples from four regions of western Russia and analyse these data in relation to micro-habitat position and selected environmental data. The testate amoebae of epiphytes are abundant but dominated by ubiquitous species. We show that there are trends toward a lower species richness and test concentration with greater elevation on the trunk and in lichens compared to mosses. There are considerable differences in community composition between sampling regions. Of all measured environmental variables only moisture content showed a significant relationship with testate amoeba community structure. Our data highlight how little is known about testate amoeba communities of this habitat and call for greater research efforts, particularly in less-studied regions and biomes. Copyright © 2015 Elsevier GmbH. All rights reserved.

  10. Behavioural differentiation induced by environmental variation when crossing a toxic zone in an amoeba

    International Nuclear Information System (INIS)

    Kunita, Itsuki; Kuroda, Shigeru; Nakagaki, Toshiyuki; Ueda, Kei-Ichi; Akita, Dai

    2017-01-01

    Organisms choose from among various courses of action in response to a wide variety of environmental conditions and the mechanism by which various behaviours are induced is an open question. Interesting behaviour was recently reported: that a unicellular organism of slime mold Physarum polycephalum known as an amoeba had multiple responses (crossing, returning, etc) when the amoeba encounters a zone with toxic levels of quinine, even under carefully controlled conditions. We here examined this elegant example in more detail to obtain insight into behavioural differentiation. We found that the statistical distribution of passage times across a quinine zone switch from unimodal to bimodal (with peaks corresponding to fast crossing and no crossing) when a periodic light stimulation to modulate a biorhythm in amoeba is applied homogeneously across the space, even under the same level of chemical stimuli. Based on a mathematical model for cell movement in amoeba, we successfully reproduced the stimulation-induced differentiation, which was observed experimentally. These dynamics may be explained by a saddle structure around a canard solution. Our results imply that the differentiation of behavioural types in amoeba is modified step-by-step via the compounding of stimulation inputs. The complex behaviour like the differentiation in amoeba may provide a basis for understanding the mechanism of behaviour selection in higher animals from an ethological perspective. (paper)

  11. Behavioural differentiation induced by environmental variation when crossing a toxic zone in an amoeba

    Science.gov (United States)

    Kunita, Itsuki; Ueda, Kei-Ichi; Akita, Dai; Kuroda, Shigeru; Nakagaki, Toshiyuki

    2017-09-01

    Organisms choose from among various courses of action in response to a wide variety of environmental conditions and the mechanism by which various behaviours are induced is an open question. Interesting behaviour was recently reported: that a unicellular organism of slime mold Physarum polycephalum known as an amoeba had multiple responses (crossing, returning, etc) when the amoeba encounters a zone with toxic levels of quinine, even under carefully controlled conditions. We here examined this elegant example in more detail to obtain insight into behavioural differentiation. We found that the statistical distribution of passage times across a quinine zone switch from unimodal to bimodal (with peaks corresponding to fast crossing and no crossing) when a periodic light stimulation to modulate a biorhythm in amoeba is applied homogeneously across the space, even under the same level of chemical stimuli. Based on a mathematical model for cell movement in amoeba, we successfully reproduced the stimulation-induced differentiation, which was observed experimentally. These dynamics may be explained by a saddle structure around a canard solution. Our results imply that the differentiation of behavioural types in amoeba is modified step-by-step via the compounding of stimulation inputs. The complex behaviour like the differentiation in amoeba may provide a basis for understanding the mechanism of behaviour selection in higher animals from an ethological perspective.

  12. Potentially pathogenic free-living amoebae in contact lenses of the asymptomatic contact lens wearers.

    Directory of Open Access Journals (Sweden)

    Maryam Niyyati

    2014-03-01

    Full Text Available Free-living amoebae (FLA including Acanthamoeba spp. and Hartmannella spp. are the causative agents of serious corneal infection especially within contact lens wearers. Thus contact lenses and their storage case could be a suitable niche for potentially pathogenic amoebae. The main objective of the present study was to evaluate the contamination of contact lenses to free living amoebae using morphological and sequencing based methods.Overall, 90 volunteers provided their contact lenses. All volunteers wore soft contact lenses. Both lenses were cultured in the same plate. Forty-eight of the volunteers were medical and dentistry student and 42 were ophthalmology attendees of hospitals in Tehran, Iran. All of the samples were inoculated to non-nutrient medium and monitored daily for the outgrowth of the amoebae. PCR and sequencing were performed using various primer pairs.Of the 90 volunteers, 9 (10% were positive for free-living amoebae outgrowth. Morphological analysis revealed that 3 isolates were belonged to Hartmannella genus according to small round cysts and 6 isolates were belonged to Acanthamoeba genus based on the star shape of endocysts. Sequencing revealed that Acanthamoeba belonged to T4, T3 and T5 genotype. Hartmannella were also belonged to vermiformis species.The presence of potentially pathogenic free living amoebae including Acanthamoeba and Hartmannella could be a high risk for people using soft contact lenses. These results revealed that improved clarification and professional recommendations for contact lens wearers is of utmost importance.

  13. Adaptive MscS gating in the osmotic permeability response in E. coli: the question of time.

    Science.gov (United States)

    Boer, Miriam; Anishkin, Andriy; Sukharev, Sergei

    2011-05-17

    Microorganisms adapt to osmotic downshifts by releasing small osmolytes through mechanosensitive (MS) channels. We want to understand how the small mechanosensitive channel's (MscS) activation and inactivation, both driven by membrane tension, optimize survival in varying hypoosmotic shock situations. By measuring light scattering with a stopped-flow device, we estimate bacterial swelling time as 30-50 ms. A partial solute equilibration follows within 150-200 ms, during which optical responses from cells with WT MscS deviate from those lacking MS channels. MscS opening rates estimated in patch clamp show the channels readily respond to tensions below the lytic limit with a time course faster than 20 ms and close promptly upon tension release. To address the role of the tension-insensitive inactivated state in vivo, we applied short, long, and two-step osmotic shock protocols to WT, noninactivating G113A, and fast-inactivating D62N mutants. WT and G113A showed a comparable survival in short 1 min 800 mOsm downshock experiments, but G113A was at a disadvantage under a long 60 min shock. Preshocking cells carrying WT MscS for 15 s to 15 min with a 200 mOsm downshift did not sensitize them to the final 500 mOsm drop in osmolarity of the second step. However, these two-step shocks induced death in D62N more than just a one-step 700 mOsm downshift. We conclude MscS is able to activate and exude osmolytes faster than lytic pressure builds inside the cell under abrupt shock. During prolonged shocks, gradual inactivation prevents continuous channel activity and assists recovery. Slow kinetics of inactivation in WT MscS ensures that mild shocks do not inactivate the entire population, leaving some protection should conditions worsen.

  14. Biphasic adaptation to osmotic stress in the C. elegans germ line.

    Science.gov (United States)

    Davis, Michael; Montalbano, Andrea; Wood, Megan P; Schisa, Jennifer A

    2017-06-01

    Cells respond to environmental stress in multiple ways. In the germ line, heat shock and nutritive stress trigger the assembly of large ribonucleoprotein (RNP) granules via liquid-liquid phase separation (LLPS). The RNP granules are hypothesized to maintain the quality of oocytes during stress. The goal of this study was to investigate the cellular response to glucose in the germ line and determine if it is an osmotic stress response. We found that exposure to 500 mM glucose induces the assembly of RNP granules in the germ line within 1 h. Interestingly, the RNP granules are maintained for up to 3 h; however, they dissociate after longer periods of stress. The RNP granules include processing body and stress granule proteins, suggesting shared functions. Based on several lines of evidence, the germ line response to glucose largely appears to be an osmotic stress response, thus identifying osmotic stress as a trigger of LLPS. Although RNP granules are not maintained beyond 3 h of osmotic stress, the quality of oocytes does not appear to decrease after longer periods of stress, suggesting a secondary adaptation in the germ line. We used an indirect marker of glycerol and observed high levels after 5 and 20 h of glucose exposure. Moreover, in gpdh-1;gpdh-2 germ lines, glycerol levels are reduced concomitant with RNP granules being maintained for an extended period. We speculate that increased glycerol levels may function as a secondary osmoregulatory adaptive response in the germ line, following a primary response of RNP granule assembly. Copyright © 2017 the American Physiological Society.

  15. Influence of static magnetic fields in phototaxis and osmotic stress in Gymnodinium catenatum (Dinophyceae).

    Science.gov (United States)

    Vale, Paulo

    2017-07-01

    Phototaxis response of the toxic microalgae Gymnodinium catenatum was studied in vitro. The percentage of cells remaining at mid-depth 20 min after stirring increased with solar radio, X-ray and solar flares output. It also increased with geomagnetic activity and temperature, and was dependent on culture time. Increase in the local static magnetic field with a permanent magnet did not influence the positive phototaxis response. However, survival and growth to a provoked hypo-osmotic shock in an altered static magnetic field was dependent on culture time and geomagnetic activity at a threshold below 22 nT. The results from phototaxis and hypo-osmotic shock experiments were in line with the previous hypothesis for the existence of two separate deleterious mechanisms conditioning the natural blooms of G. catenatum: one that is dependent on solar radiation and the other that is related to geomagnetic activity. Variations in electromagnetic fields caused by tectonic activity were also capable of influencing G. catenatum phototaxis and growth response in vitro.

  16. Enhanced monoclonal antibody production by gradual increase of osmotic pressure

    OpenAIRE

    Lin, Jianqiang; Takagi, Mutsumi; Qu, Yinbo; Gao, Peiji; Yoshida, Toshiomi

    1999-01-01

    The time length required for the adaptation of AFP-27 hybridoma cells to high osmotic pressure and the effect of a gradual increase of osmotic pressure on monoclonal antibody production were investigated. When the cells were subjected to an increase of osmotic pressure from 300 mOsmol kg-1 to 366 mOsmol kg- 1, the intracellular content of osmoprotective free amino acids reached a maximum level 6 h after the osmotic pressure was increased to 366 mOsmol kg-1. The same time period of 6 h incubat...

  17. Toxic shock syndrome

    Science.gov (United States)

    Staphylococcal toxic shock syndrome; Toxic shock-like syndrome; TSLS ... Toxic shock syndrome is caused by a toxin produced by some types of staphylococcus bacteria. A similar problem, called toxic shock- ...

  18. A Simple Student Laboratory on Osmotic Flow, Osmotic Pressure, and the Reflection Coefficient.

    Science.gov (United States)

    Feher, Joseph J.; Ford, George D.

    1995-01-01

    Describes a laboratory exercise containing a practical series of experiments that novice students can perform within two hours. The exercise provides a confirmation of van't Hoff's law while placing more emphasis on osmotic flow than pressure. Students can determine parameters such as the reflection coefficient which stress the interaction of both…

  19. Distribution of free-living amoebae in a treatment system of textile industrial wastewater.

    Science.gov (United States)

    Ramirez, Elizabeth; Robles, Esperanza; Martinez, Blanca; Ayala, Reynaldo; Sainz, Guadalupe; Martinez, Maria Elena; Gonzalez, Maria Elena

    2014-11-01

    Free-living amoebae have been found in soil, air and a variety of aquatic environments, but few studies have been conducted on industrial wastewater and none on wastewater from the textile industry. The aim of this study was to determine the presence and distribution of free-living amoebae in a biological treatment system that treats textile industrial wastewater. Samples were taken from input, aeration tank, sedimentation tank and output. Samples were centrifuged at 1200g for 15min, the sediment was seeded on non-nutritive agar with Enterobacter aerogenes (NNE) and the plates were incubated at 30 and 37°C. Free-living amoebae were present in all stages of the treatment system. The highest number of amoebic isolates was found in the aeration tank and no seasonal distribution was observed during the year. A total of 14 amoeba genera were isolated: Acanthamoeba, Echinamoeba, Korotnevella, Mayorella, Naegleria, Platyamoeba, Saccamoeba, Stachyamoeba, Thecamoeba, Vahlkampfia, Vannella, Vermamoeba, Vexillifera and Willaertia. The most frequently found amoebae were Acanthamoeba and Vermamoeba which were found in all treatment system stages. The constant presence and diversity of free-living amoebae in the treatment system were important findings due to the characteristics of the wastewater from the textile plant in terms of the residue content from colorants, fixers, carriers, surfactants, etc., used in fabric dyeing and finishing processes. The factors that determined the presence and distribution of amoebae in the activated sludge system were their capacity to form cysts, which allowed them to resist adverse conditions; food availability; an average temperature of 27-33°C; dissolved oxygen in average concentrations above 2mg/L, and pH in a range of 5.9-7.1. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Review: Occurrence of the pathogenic amoeba Naegleria fowleri in groundwater

    Science.gov (United States)

    Bright, Kelly R.; Gerba, Charles P.

    2017-06-01

    Naegleria fowleri is a thermophilic free-living amoeba found worldwide in soils and warm freshwater. It is the causative agent of primary amebic meningoencephalitis, a nearly always fatal disease afflicting mainly children and young adults. Humans are exposed to the organism via swimming, bathing, or other recreational activity during which water is forcefully inhaled into the upper nasal passages. Although many studies have looked at the occurrence of N. fowleri in surface waters, limited information is available regarding its occurrence in groundwater and geothermally heated natural waters such as hot springs. This paper reviews the current literature related to the occurrence of N. fowleri in these waters and the methods employed for its detection. Case reports of potential groundwater exposures are also included. Despite increased interest in N. fowleri in recent years due to well-publicized cases linked to drinking water, many questions still remain unanswered. For instance, why the organism persists in some water sources and not in others is not well understood. The role of biofilms in groundwater wells and plumbing in individual buildings, and the potential for warming due to climate change to expand the occurrence of the organism into new regions, are still unclear. Additional research is needed to address these questions in order to better understand the ecology of N. fowleri and the conditions that result in greater risks to bathers.

  1. Genotypic characterization of amoeba isolated from Acanthamoeba keratitis in Poland.

    Science.gov (United States)

    Derda, Monika; Solarczyk, Piotr; Cholewiński, Marcin; Hadaś, Edward

    2015-03-01

    Free-living amoebae belonging to the genus Acanthamoeba are the causative factor of many diseases. Among others, they cause Acanthamoeba keratitis (AK), a condition that usually occurs in contact lens wearers, though it is also observed in non-wearers. The number of diagnosed cases of AK increased more than eightfold during 8 years in the USA, and a proportional increase in frequency also occurred in Poland and Europe. Cases of AK are usually diagnosed late, and their therapy is difficult and rarely successful. AK is an uncommon diagnosis in Poland. The increased number of positive cases observed in our laboratory may reflect the growing at-risk population of contact lens wearers. Acanthamoeba as a genus of facultative human parasites is currently classified into 17 genotypes. Isolates belonging to seven genotypes were found to be associated with AK. One genotype in particular, T4, was found to be overrepresented in human disease. The main finding of our study is that in Poland, AK is almost always associated with the T4 genotype.

  2. Detection of the amoeba Entamoeba gingivalis in periodontal pockets

    Science.gov (United States)

    Bonner, Mark; Amard, Véronique; Bar-Pinatel, Charlotte; Charpentier, Frédéric; Chatard, Jean-Michel; Desmuyck, Yvan; Ihler, Serge; Rochet, Jean-Pierre; Roux de La Tribouille, Véronique; Saladin, Luc; Verdy, Marion; Gironès, Núria; Fresno, Manuel; Santi-Rocca, Julien

    2014-01-01

    Periodontitis is a public health issue, being one of the most prevalent diseases worldwide. However, the aetiology of the disease is still unclear: genetics of patients cannot explain the dispersed or isolated localisation of gingival pockets, while bacteria-based models are insufficient to distinguish gingivitis and periodontitis. The possible role of parasites in the establishment of periodontitis has been poorly studied until now. The aim of this project was to study a potential link between colonisation of gingival crevices by the amoeba Entamoeba gingivalis and periodontitis. In eight different dental clinics in France, samples were taken in periodontal pockets (72) or healthy sites (33), and submitted to microscopic observation and molecular identification by PCR with a new set of primers designed to specifically detect E. gingivalis. This blind sample analysis showed the strong sensitivity of PCR compared with clinical diagnosis (58/72 = 81%), and microscopy (51/65 = 78%). The results of this work show that the parasites detected by microscopy mainly – if not exclusively – belong to the species E. gingivalis and that the presence of the parasite is correlated with periodontitis. PMID:24983705

  3. The plant cuticle is required for osmotic stress regulation of abscisic acid biosynthesis and osmotic stress tolerance in Arabidopsis

    KAUST Repository

    Wang, Zhenyu

    2011-05-01

    Osmotic stress activates the biosynthesis of abscisic acid (ABA). One major step in ABA biosynthesis is the carotenoid cleavage catalyzed by a 9-cis epoxycarotenoid dioxygenase (NCED). To understand the mechanism for osmotic stress activation of ABA biosynthesis, we screened for Arabidopsis thaliana mutants that failed to induce the NCED3 genee xpression in response to osmotic stress treatments. The ced1 (for 9-cis epoxycarotenoid dioxy genase defective 1) mutant isolated in this study showed markedly reduced expression of NCED3 in response to osmotic stress (polyethylene glycol)treatments compared with the wild type. Other ABA biosynthesis genes are also greatly reduced in ced1 under osmotic stress. ced1 mutant plants are very sensitive to even mild osmotic stress. Map-based cloning revealed unexpectedly thatCED1 encodes a putative a/b hydrolase domain-containing protein and is allelic to the BODYGUARD gene that was recently shown to be essential for cuticle biogenesis. Further studies discovered that other cut in biosynthesis mutants are also impaired in osmotic stress induction of ABA biosynthesis genes and are sensitive to osmotic stress. Our work demonstrates that the cuticle functions not merely as a physical barrier to minimize water loss but also mediates osmotic stress signaling and tolerance by regulating ABA biosynthesis and signaling. © 2011 American Society of Plant Biologists. All rights reserved.

  4. Osmotic stress on nitrification in an airlift bioreactor

    International Nuclear Information System (INIS)

    Jin Rencun; Zheng Ping; Mahmood, Qaisar; Hu Baolan

    2007-01-01

    The effect of osmotic pressure on nitrification was studied in a lab-scale internal-loop airlift-nitrifying reactor. The reactor slowly adapted to the escalating osmotic pressure during 270 days operation. The conditions were reversed to the initial stage upon full inhibition of the process. Keeping influent ammonium concentration constant at 420 mg N L -1 and hydraulic retention time at 20.7 h, with gradual increase in osmotic pressure from 4.3 to 18.8 x 10 5 Pa by adding sodium sulphate, the ammonium removal efficiencies of the nitrifying bioreactor were maintained at 93-100%. Further increase in osmotic pressure up to 19.2 x 10 5 Pa resulted in drop of the ammonium conversion to 69.2%. The osmotic pressure caused abrupt inhibition of nitrification without any alarm and the critical osmotic pressure value causing inhibition remained between 18.8 and 19.2 x 10 5 Pa. Nitrite oxidizers were found more sensitive to osmotic stress as compared with ammonia oxidizers, leading to nitrite accumulation up to 61.7% in the reactor. The performance of bioreactor recovered gradually upon lowering the osmotic pressure. Scanning and transmission electron microscopy indicated that osmotic stress resulted in simplification of the nitrifying bacterial populations in the activated sludge as the cellular size reduced; the inner membrane became thinner and some unknown inclusions appeared within the cells. The microbial morphology and cellular structure restored upon relieving the osmotic pressure. Addition of potassium relieved the effect of osmotic pressure upon nitrification. Results demonstrate that the nitrifying reactor possesses the potential to treat ammonium-rich brines after acclimatization

  5. Osmotic properties of sulfobutylether and hydroxypropyl cyclodextrins.

    Science.gov (United States)

    Zannou, E A; Streng, W H; Stella, V J

    2001-08-01

    The purpose of this study was to determine the osmolality of sulfobutylether (SBE) and hydroxypropyl (HP) derivatives of cyclodextrins (CDs) via vapor pressure osmometry (VPO) and freezing point depression (FPD). (SBE) and HP-CDs are efficient excipients capable of solubilizing and stabilizing poorly water-soluble drugs in parenteral formulations. (SBE)-CDs have also been used as solubility enhancers and osmotic agents for the sustained release of poorly water-soluble drugs from osmotic pump tablets. The knowledge of the CD's osmolality in solution or inside such tablets would allow one to further characterize the release mechanisms. Experiments were conducted at 37 degrees C with eight types of HP and (SBE)-CDs. The aqueous solutions ranged from 0.005-0.350 mol(-1). Methods were developed to allow the measurement of high osmolalities using a vapor pressure osmometer or a differential scanning calorimeter. The osmolality calculations from the VPO and FPD measurements correlated well. The osmolality of (SBE)-CDs was significantly higher than the osmolality of HP-CDs and increased with the total degree of substitution (TDS). All CDs showed deviations from ideality at high concentrations. Empirical correlations of osmolality with concentration and TDS allowed the prediction of osmolality over a wide concentration range. This study also gave some useful insights into the behavior of CD derivatives in solution.

  6. demystifying the shock of shocking

    African Journals Online (AJOL)

    aimed at depolarising a myocardium that is not generating a co-ordinated, perfusing rhythm. Organised QRS complexes cannot be identified and the electrical current is delivered without synchronising with the patient's native rhythm. DC shock should not be delayed once a shockable rhythm is recognised. The longer the ...

  7. Origin and diversity of testate amoebae shell composition: Example of Bullinularia indica living in Sphagnum capillifolium.

    Science.gov (United States)

    Delaine, Maxence; Bernard, Nadine; Gilbert, Daniel; Recourt, Philippe; Armynot du Châtelet, Eric

    2017-06-01

    Testate amoebae are free-living shelled protists that build a wide range of shells with various sizes, shapes, and compositions. Recent studies showed that xenosomic testate amoebae shells could be indicators of atmospheric particulate matter (PM) deposition. However, no study has yet been conducted to assess the intra-specific mineral, organic, and biologic grain diversity of a single xenosomic species in a natural undisturbed environment. This study aims at providing new information about grain selection to develop the potential use of xenosomic testate amoebae shells as bioindicators of the multiple-origin mineral/organic diversity of their proximal environment. To fulfil these objectives, we analysed the shell content of 38 Bullinularia indica individuals, a single xenosomic testate amoeba species living in Sphagnum capillifolium, by scanning electron microscope (SEM) coupled with X-ray spectroscopy. The shells exhibited high diversities of mineral, organic, and biomineral grains, which confirms their capability to recycle xenosomes. Mineral grain diversity and size of B. indica matched those of the atmospheric natural mineral PM deposited in the peatbog. Calculation of grain size sorting revealed a discrete selection of grains agglutinated by B. indica. These results are a first step towards understanding the mechanisms of particle selection by xenosomic testate amoebae in natural conditions. Copyright © 2017 Elsevier GmbH. All rights reserved.

  8. LPS-inducible factor(s) from activated macrophages mediates cytolysis of Naegleria fowleri amoebae

    Energy Technology Data Exchange (ETDEWEB)

    Cleary, S.F.; Marciano-Cabral, F.

    1986-03-01

    Soluble cytolytic factors of macrophage origin have previously been described with respect to their tumoricidal activity. The purpose of this study was to investigate the mechanism and possible factor(s) responsible for cytolysis of the amoeba Naegleria fowleri by activated peritoneal macrophages from B6C3F1 mice. Macrophages or conditioned medium (CM) from macrophage cultures were incubated with /sup 3/H-Uridine labeled amoebae. Percent specific release of label served as an index of cytolysis. Bacille Calmette-Guerin (BCG) and Corynebacterium parvum macrophages demonstrated significant cytolysis of amoebae at 24 h with an effector to target ratio of 10:1. Treatment of macrophages with inhibitors of RNA or protein synthesis blocked amoebicidal activity. Interposition of a 1 ..mu..m pore membrane between macrophages and amoebae inhibited killing. Inhibition in the presence of the membrane was overcome by stimulating the macrophages with LPS. CM from SPS-stimulated, but not unstimulated, cultures of activated macrophages was cytotoxic for amoebae. The activity was heat sensitive and was recovered from ammonium sulfate precipitation of the CM. Results indicate that amoebicidal activity is mediated by a protein(s) of macrophage origin induced by target cell contact or stimulation with LPS.

  9. Proteases from Entamoeba spp. and Pathogenic Free-Living Amoebae as Virulence Factors

    Science.gov (United States)

    Serrano-Luna, Jesús; Piña-Vázquez, Carolina; Reyes-López, Magda; Ortiz-Estrada, Guillermo

    2013-01-01

    The standard reference for pathogenic and nonpathogenic amoebae is the human parasite Entamoeba histolytica; a direct correlation between virulence and protease expression has been demonstrated for this amoeba. Traditionally, proteases are considered virulence factors, including those that produce cytopathic effects in the host or that have been implicated in manipulating the immune response. Here, we expand the scope to other amoebae, including less-pathogenic Entamoeba species and highly pathogenic free-living amoebae. In this paper, proteases that affect mucin, extracellular matrix, immune system components, and diverse tissues and cells are included, based on studies in amoebic cultures and animal models. We also include proteases used by amoebae to degrade iron-containing proteins because iron scavenger capacity is currently considered a virulence factor for pathogens. In addition, proteases that have a role in adhesion and encystation, which are essential for establishing and transmitting infection, are discussed. The study of proteases and their specific inhibitors is relevant to the search for new therapeutic targets and to increase the power of drugs used to treat the diseases caused by these complex microorganisms. PMID:23476670

  10. Detection and identification of free-living amoeba from aquatic environment in Taiwan

    Science.gov (United States)

    Jiun Tzeng, Kai; Che Tung, Min; Hsu, Bing Mu; Tsai, Hsiu Feng; Huang, Po Hsiang; Hao Huang, Kuan; Kao, Po Min; Shen, Shu Min; Chen, Jung Sheng

    2013-04-01

    Free-living amoebae including Acanthamoeba, Naegleria, Balamuthia and Hartmannella are widely distributed in water, soil, and air. They can infect humans and can lead to serious illness even death. The aim of this study is to investigate the presence of free-living amoebae from aquatic environment in Taiwan, and to compare the differences between Acanthamoeba and Naegleria in different cultivation methods and conditions. In this study, we used molecular method with specific primers by Polymerase Chain Reaction (PCR) to amplify and to analyze the occurrence of free-living amoebae in aquatic environment. We collected 92 samples from environmental water in Taiwan. The results show that 33 water samples (35.9%) and 11 water samples (12.0%) were detected positive for Acanthamoeba and Naegleria, respectively. Furthermore, both Acanthamoeba and Naegleria can be cultured by PYG in 30° C, but not all free-living amoebae can be enriched and isolated by using storage-cultivation method. Due to the presence of Acanthamoeba and Naegleria in aquatic environment, the water quality monitoring should be more conscious. Keywords: free-living amoebae; Acanthamoeba; Naegleria; Balamuthia; Hartmannella; PCR

  11. Erythrocyte osmotic fragility of pigs administered ascorbic acid and ...

    African Journals Online (AJOL)

    Blood samples for erythrocyte osmotic fragility determination which was done using standard procedure, were taken early in the morning a day before transportation, immediately after and a week after transportation. Erythrocyte osmotic fragility decreased significantly (P < 0.05) at NaCl concentration of 0.85, 0.80 and 0.70% ...

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

    African Journals Online (AJOL)

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

  13. A physiological evaluation of the enhanced osmotic stress tolerance ...

    African Journals Online (AJOL)

    Leaf water potential and relative water content were also determined. SR3 leaves were more effective in accumulating proline and soluble sugar than those of Jinan 177, and their osmotic potential was significantly reduced in response to the applied osmotic stress. The mean increase in the activities of SOD, POD and APX ...

  14. Improved Erythrocyte Osmotic Fragility and Packed Cell Volume ...

    African Journals Online (AJOL)

    Improved Erythrocyte Osmotic Fragility and Packed Cell Volume following administration of Aloe barbadensis Juice Extract in Rats. ... Abstract. Aloe barbadensis is a popular house plant that has a long history of a multipurpose folk remedy. ... Keywords: osmotic fragility, packed cell volume, haemoglobin, Aloe vera ...

  15. Osmotic Power: A Fresh Look at an Old Experiment

    Science.gov (United States)

    Dugdale, Pam

    2014-01-01

    Electricity from osmotic pressure might seem a far-fetched idea but this article describes a prototype in Norway where the osmotic pressure generated between salt and fresh water drives a turbine. This idea was applied in a student investigation, where they were tasked with researching which alternative materials could be used for the…

  16. Drying of carrots in slices with osmotic dehydration

    African Journals Online (AJOL)

    SAM

    2014-07-23

    Jul 23, 2014 ... According to Torreggiani (1993), osmotic dehydration is a special method of drying which is based on the principle that when cellular material are immersed in a hypertonic aqueous solution, a driving force for water removal sets up because of the higher osmotic pressure of the hypertonic solution.

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

    African Journals Online (AJOL)

    USER

    2010-06-21

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

  18. Shock Waves

    CERN Document Server

    Jiang, Z

    2005-01-01

    The International Symposium on Shock Waves (ISSW) is a well established series of conferences held every two years in a different location. A unique feature of the ISSW is the emphasis on bridging the gap between physicists and engineers working in fields as different as gas dynamics, fluid mechanics and materials sciences. The main results presented at these meetings constitute valuable proceedings that offer anyone working in this field an authoritative and comprehensive source of reference.

  19. Cardiogenic Shock.

    Science.gov (United States)

    Moskovitz, Joshua B; Levy, Zachary D; Slesinger, Todd L

    2015-08-01

    Cardiogenic shock is the leading cause of morbidity and mortality in patients presenting with acute coronary syndrome. Although early reperfusion strategies are essential to the management of these critically ill patients, additional treatment plans are often needed to stabilize and treat the patient before reperfusion may be possible. This article discusses pharmacologic and surgical interventions, their indications and contraindications, management strategies, and treatment algorithms. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. NAEGLARIA FOWLERI: THE BRAIN EATING AMOEBA OR AN ENIGMA?

    Science.gov (United States)

    Mukhtar, Fatima; Wazir, Mohammad Salim

    2015-01-01

    Naeglaria fowleri (N. fowleri), popularly known as the brain eating amoeba is the causative agent of the fulminant disease, primary amoebic meningoencephalitis (PAM). Although a rare disease, it is a threat to human health with a case fatality rate ranging from 95-99%. PAM cases have been reported from the United States of America, Australia, Europe and Asia. From 1962 to 2014, 133 people have been infected by N. fowleri in the USA, out of which only three have survived. None of the PAM cases reported in Pakistan so far has survived. This underscores the importance to identify factors, which have led to the failure in decreasing case fatality associated with N. fowleri despite major advances in medical technology, health care; and prevention and control strategies since the first reported case in 1965. We need to focus on eliciting risk factors of the disease prevalent in our part of the world, which are at variance with the developed world. A predominant number. of PAM cases in the West are reported in young males who had participated in recreational activities. However, majority of cases reported in Pakistan are also among young males but they were linked with the religious practice of ablution. What is required to better understand and hence manage this enigma is further research. Further research is to be conducted to discover potent antimicrobials, to test the effectiveness of the new transcribial device in managing PAM, and to identify host factors, which make an individual susceptible to N. fowleri. Investigation of environmental factors related to N. fowleri also needs to be done. Doing so is of paramount importance, as it will help identify the preventive strategies to be employed against N. fowleri.

  1. Late Holocene palaeohydrological changes in a Sphagnum peat bog from NW Romania based on testate amoebae

    Directory of Open Access Journals (Sweden)

    Andrei-Cosmin Diaconu

    2016-04-01

    Full Text Available This paper investigates the possibility of reconstructing the palaeohydrological changes in an active Sphagnum peat bog from north-western Romania using testate amoebae fauna and organic matter content determined by loss on ignition (LOI. In total 28 taxa of testate amoebae were identified of which 11 were frequent enough to present a remarkable ecological significance. Based on the relative abundance of these taxa nine zones were identified, crossing from very wet to dry climate conditions. The wet periods identified are characterized by taxa like Centropyxis cassis, Amphitrema flavum and Hyalosphenia papilio, while in the dry periods Difflugia pulex and Nebela militaris thrive. We showed that combining qualitative information regarding hydrological preferences with the quantitative percentage data from the fossil record it is possible to obtain information regarding major surface moisture changes from the peat bog surface. Furthermore we identified a link between distribution of testate amoebae assemblages, organic matter variation and minerogenic material.

  2. Free energy simulations with the AMOEBA polarizable force field and metadynamics on GPU platform.

    Science.gov (United States)

    Peng, Xiangda; Zhang, Yuebin; Chu, Huiying; Li, Guohui

    2016-03-05

    The free energy calculation library PLUMED has been incorporated into the OpenMM simulation toolkit, with the purpose to perform enhanced sampling MD simulations using the AMOEBA polarizable force field on GPU platform. Two examples, (I) the free energy profile of water pair separation (II) alanine dipeptide dihedral angle free energy surface in explicit solvent, are provided here to demonstrate the accuracy and efficiency of our implementation. The converged free energy profiles could be obtained within an affordable MD simulation time when the AMOEBA polarizable force field is employed. Moreover, the free energy surfaces estimated using the AMOEBA polarizable force field are in agreement with those calculated from experimental data and ab initio methods. Hence, the implementation in this work is reliable and would be utilized to study more complicated biological phenomena in both an accurate and efficient way. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  3. Osmotic mechanism of the loop extrusion process

    Science.gov (United States)

    Yamamoto, Tetsuya; Schiessel, Helmut

    2017-09-01

    The loop extrusion theory assumes that protein factors, such as cohesin rings, act as molecular motors that extrude chromatin loops. However, recent single molecule experiments have shown that cohesin does not show motor activity. To predict the physical mechanism involved in loop extrusion, we here theoretically analyze the dynamics of cohesin rings on a loop, where a cohesin loader is in the middle and unloaders at the ends. Cohesin monomers bind to the loader rather frequently and cohesin dimers bind to this site only occasionally. Our theory predicts that a cohesin dimer extrudes loops by the osmotic pressure of cohesin monomers on the chromatin fiber between the two connected rings. With this mechanism, the frequency of the interactions between chromatin segments depends on the loading and unloading rates of dimers at the corresponding sites.

  4. [The role of the floodplain gradient in structuring of testate amoebae communities in the Ilych River].

    Science.gov (United States)

    Mazeĭ, Iu A; Malysheva, E A; Lapteva, E M; Komarov, A A; Taskaeva, A A

    2012-01-01

    Forty-two testate amoebae taxa were identified in alluvial soils of floodplain islands in the Ilych River. Among the pedo- and eurybionts, there were aquatic rhizopods. Along the floodplain transect (willow --> meadow --> deciduous forest --> coniferous forest), the testate amoebae community changed directly. There are spatially homogeneous (low beta-diversity) testacean communities but species rich on the local level (high alpha-diversity) within forests. Within willows and meadows, communities are characterized by low alpha-diversity and high heterogeneity that leads to high gamma-diversity.

  5. Salt Effect on Osmotic Pressure of Polyelectrolyte Solutions: Simulation Study

    Directory of Open Access Journals (Sweden)

    Jan-Michael Y. Carrillo

    2014-07-01

    Full Text Available Abstract: We present results of the hybrid Monte Carlo/molecular dynamics simulations of the osmotic pressure of salt solutions of polyelectrolytes. In our simulations, we used a coarse-grained representation of polyelectrolyte chains, counterions and salt ions. During simulation runs, we alternate Monte Carlo and molecular dynamics simulation steps. Monte Carlo steps were used to perform small ion exchange between simulation box containing salt ions (salt reservoir and simulation box with polyelectrolyte chains, counterions and salt ions (polyelectrolyte solution. This allowed us to model Donnan equilibrium and partitioning of salt and counterions across membrane impermeable to polyelectrolyte chains. Our simulations have shown that the main contribution to the system osmotic pressure is due to salt ions and osmotically active counterions. The fraction of the condensed (osmotically inactive counterions first increases with decreases in the solution ionic strength then it saturates. The reduced value of the system osmotic coefficient is a universal function of the ratio of the concentration of osmotically active counterions and salt concentration in salt reservoir. Simulation results are in a very good agreement with osmotic pressure measurements in sodium polystyrene sulfonate, DNA, polyacrylic acid, sodium polyanetholesulfonic acid, polyvinylbenzoic acid, and polydiallyldimethylammonium chloride solutions.

  6. Mycobacterium tuberculosis complex mycobacteria as amoeba-resistant organisms.

    Directory of Open Access Journals (Sweden)

    Felix Mba Medie

    Full Text Available BACKGROUND: Most environmental non-tuberculous mycobacteria have been demonstrated to invade amoebal trophozoites and cysts, but such relationships are largely unknown for members of the Mycobacterium tuberculosis complex. An environmental source has been proposed for the animal Mycobacterium bovis and the human Mycobacterium canettii. METHODOLOGY/PRINCIPAL FINDINGS: Using optic and electron microscopy and co-culture methods, we observed that 89±0.6% of M. canettii, 12.4±0.3% of M. tuberculosis, 11.7±2% of M. bovis and 11.2±0.5% of Mycobacterium avium control organisms were phagocytized by Acanthamoeba polyphaga, a ratio significantly higher for M. canettii (P = 0.03, correlating with the significantly larger size of M. canetti organisms (P = 0.035. The percentage of intraamoebal mycobacteria surviving into cytoplasmic vacuoles was 32±2% for M. canettii, 26±1% for M. tuberculosis, 28±2% for M. bovis and 36±2% for M. avium (P = 0.57. M. tuberculosis, M. bovis and M. avium mycobacteria were further entrapped within the double wall of <1% amoebal cysts, but no M. canettii organisms were observed in amoebal cysts. The number of intracystic mycobacteria was significantly (P = 10(-6 higher for M. avium than for the M. tuberculosis complex, and sub-culturing intracystic mycobacteria yielded significantly more (P = 0.02 M. avium organisms (34×10(4 CFU/mL than M. tuberculosis (42×10(1 CFU/mL and M. bovis (35×10(1 CFU/mL in the presence of a washing fluid free of mycobacteria. Mycobacteria survived in the cysts for up to 18 days and cysts protected M. tuberculosis organisms against mycobactericidal 5 mg/mL streptomycin and 2.5% glutaraldehyde. CONCLUSIONS/SIGNIFICANCE: These data indicate that M. tuberculosis complex organisms are amoeba-resistant organisms, as previously demonstrated for non-tuberculous, environmental mycobacteria. Intercystic survival of tuberculous mycobacteria, except for M. canettii, protect them

  7. On the osmotically unresponsive water compartment in cells.

    Science.gov (United States)

    Fullerton, Gary D; Kanal, Kalpana M; Cameron, Ivan L

    2006-01-01

    Differences in colligative properties (freezing point, boiling point, vapor pressure and osmotic behavior) between water in living cells and pure bulk water were investigated by re-evaluating reports of the osmotic behavior of mammalian cells. In five different animal cells, osmotically unresponsive water (OUW) values ranged from 1.1 to 2.2 g per g dry mass. Detailed analysis of human red blood cell (RBC) data indicates a major role for hemoglobin OUW-values, aggregation and packing in cell volume regulation that can be explained for the first time in relevant molecular terms.

  8. Mechanism of actuation in conducting polymers: Osmotic expansion

    DEFF Research Database (Denmark)

    Bay, Lasse; Jacobsen, Torben; West, Keld

    2001-01-01

    Conducting polymers expand or contract when their redox state is changed. This expansion/contraction effect can be separated in an intrinsic part because of changes of the polymer backbone on reduction/oxidation and a part depending on the surrounding electrolyte phase, because of osmotic expansion...... is compared with measurements on PPy(DBS) films. The experiments show that the expansion decreases as the electrolyte concentration is increased. This means that a considerable part of the total expansion is due to the osmotic effect. The osmotic effect should be taken into account when interpreting...

  9. Shock Prevention

    Science.gov (United States)

    1978-01-01

    The electrician pictured is installing a General Electric Ground Fault Interrupter (GFI), a device which provides protection against electrical shock in the home or in industrial facilities. Shocks due to defective wiring in home appliances or other electrical equipment can cause severe burns, even death. As a result, the National Electrical Code now requires GFIs in all new homes constructed. This particular type of GFI employs a sensing element which derives from technology acquired in space projects by SCI Systems, Inc., Huntsville, Alabama, producer of sensors for GE and other manufacturers of GFI equipment. The sensor is based on the company's experience in developing miniaturized circuitry for space telemetry and other spacecraft electrical systems; this experience enabled SCI to package interruptor circuitry in the extremely limited space available and to produce sensory devices at practicable cost. The tiny sensor measures the strength of the electrical current and detects current differentials that indicate a fault in the functioning of an electrical system. The sensing element then triggers a signal to a disconnect mechanism in the GFI, which cuts off the current in the faulty circuit.

  10. Osmotic and Heat Stress Effects on Segmentation

    OpenAIRE

    Weiss, Julian; Devoto, Stephen H.

    2016-01-01

    During vertebrate embryonic development, early skin, muscle, and bone progenitor populations organize into segments known as somites. Defects in this conserved process of segmentation lead to skeletal and muscular deformities, such as congenital scoliosis, a curvature of the spine caused by vertebral defects. Environmental stresses such as hypoxia or heat shock produce segmentation defects, and significantly increase the penetrance and severity of vertebral defects in genetically susceptible ...

  11. Long-term mannitol-induced osmotic stress leads to stomatal ...

    African Journals Online (AJOL)

    GREGORY

    2010-09-13

    Sep 13, 2010 ... The possible role of decreased leaf cell elasticity (εmax) is discussed in relation to osmotic stress tolerance in this species. ... cell elasticity; Ψ, osmotic potential; Ψ0, osmotic potential at turgor loss point; Ψ100, osmotic ... because they do not interfere with biochemical reactions. (Bohnert et al., 1995).

  12. Pathogenic amoebae in natural thermal waters of three resorts of Hidalgo, Mexico.

    Science.gov (United States)

    Rivera, F; Lares, F; Gallegos, E; Ramirez, E; Bonilla, P; Calderon, A; Martinez, J J; Rodriguez, S; Alcocer, J

    1989-12-01

    In a search for free-living amoebae, seven water samples from three thermal water bathing resorts in Tecozautla, Hidalgo, were analyzed during December 1984. The samples were concentrated by filtration and centrifugation, and inoculated later on monoxenic and axenic media. The identification of the isolates was performed by morphology and isoelectric focusing of isoenzymes and total proteins. Thirty-three strains of free-living amoebae belonging to the genera Naegleria, Acanthamoeba, and Willaertia were isolated. Twenty of these strains belonged to the Naegleria genus, 16 of them were classified as Naegleria spp., and 2 were classified as Naegleria lovaniensis. Noteworthy was the finding of two pathogenic strains of the species Naegleria australiensis. N. australiensis and N. lovaniensis may be considered good indicator organisms, since they live in the same environmental conditions as N. fowleri, the agent of primary amoebic encephalitis (PAM). On the other hand, amoebae other than Naegleria were isolated and identified as Acathamoeba castellanii (two strains), and Acanthamoeba lugdunensis (one strain), which proved to be pathogenic when tested in mice. Nine more pathogenic strains of the genus Acanthamoeba spp. were isolated together with one strain of Willaertia magna, a thermophilic nonpathogenic amoeba. The chlorination and periodical surveillance of water resorts like the one studied is recommended, in order to prevent the appearance of more cases of PAM or other human diseases associated with pathogenic Acanthamoeba spp.

  13. Presence of rotavirus and free-living amoebae in the water supplies of Karachi, Pakistan

    Science.gov (United States)

    Yousuf, Farzana Abubakar; Siddiqui, Ruqaiyyah; Khan, Naveed Ahmed

    2017-01-01

    ABSTRACT Rotavirus and pathogenic free-living amoebae are causative agents of important health problems, especially for developing countries like Pakistan where the population has limited access to clean water supplies. Here, we evaluated the prevalence of rotavirus and free-living amoebae (Acanthamoeba spp., Balamuthia mandrillaris, Naegleria fowleri) in drinking water supplies of Karachi, Pakistan. Six water filtration plants that supply drinking water to the population of Karachi were investigated. Additionally, drinking water samples from households were analyzed for the presence of rotavirus and free-living amoebae. Rotavirus was present in 35% of the water samples collected from water filtration plants; however, domestic tap water samples had a prevalence of only 5%. Out of 20 water samples from filtration plants, 13 (65%) were positive for Acanthamoeba spp., and one (5%) was positive for B. mandrillaris. Out of 20 drinking water samples collected from different areas of Karachi, 35% were positive for Acanthamoeba spp. Rotavirus was detected in 5% of the drinking water samples tested. Overall, these findings showed for the first time the presence of rotavirus, in addition to pathogenic free-living amoebae in drinking water supplies of Karachi that could be an important public health risk for the affected population. PMID:28591260

  14. Quadrulella texcalense sp nov from a Mexican desert: An unexpected new environment for hyalospheniid testate amoebae

    Czech Academy of Sciences Publication Activity Database

    Perez-Juarez, H.; Serrano-Vazquez, A.; Kosakyan, Anush; Mitchell, E.A.D.; Rivera Aguilar, V. M.; Lahr, D. J. G.; Hernandez Moreno, M. M.; Macías Cuellar, H.; Eguiarte, L. E.; Lara, E.

    2017-01-01

    Roč. 61, 17 July (2017), s. 253-264 ISSN 0932-4739 Institutional support: RVO:60077344 Keywords : Adaptation * Biological soil crust desert * Protist * Tehuacain-Cuicatlain Biosphere Reserve * Testate amoebae Subject RIV: EG - Zoology OBOR OECD: Zoology Impact factor: 2.581, year: 2016

  15. Free-living amoebae used to isolate consortia capable of degrading trichloroethylene

    Energy Technology Data Exchange (ETDEWEB)

    Tyndall, R.L.; Katz, D.S.; Little, C.D. [Oak Ridge National Lab., TN (United States); Kennedy, J.R. [Univ. of Tennessee, Knoxville, TN (United States)

    1991-12-31

    The interaction of protozoa with prokaryotes is well documented. These interactions can be either ecto- or endosymbiotic. An example of photosynthetic symbiosis is the well-defined interaction between paramecium and entrapped Chlorella. Paramecium can also form symbiotic relationships with gram-negative heterotrophic bacteria. Jeon has described an interaction between amoebae and engulfed bacteria, that eventuated into a dependency of the amoebae on the presence of the engulfed bacterium. Free-living amoebae and tetrahymena can engulf and subsequently provide the necessary niche for the replication of Legionella. Acanthamoebae trophozoites and cysts can harbor and support the replication of unidentified gram-negative bacteria. King has recently shown that bacteria associated with free-living amoebae are more resistant to toxic environments. Assuming that methylotrophic bacteria in situ are a part of a mixed community, and based on our observations that bacteria associated with protozoa may not be easily isolated by standard techniques, we attempted to use protozoa as a tool to isolate TCE-degrading bacteria.

  16. Presence of rotavirus and free-living amoebae in the water supplies of Karachi, Pakistan

    Directory of Open Access Journals (Sweden)

    Farzana Abubakar Yousuf

    Full Text Available ABSTRACT Rotavirus and pathogenic free-living amoebae are causative agents of important health problems, especially for developing countries like Pakistan where the population has limited access to clean water supplies. Here, we evaluated the prevalence of rotavirus and free-living amoebae (Acanthamoeba spp., Balamuthia mandrillaris, Naegleria fowleri in drinking water supplies of Karachi, Pakistan. Six water filtration plants that supply drinking water to the population of Karachi were investigated. Additionally, drinking water samples from households were analyzed for the presence of rotavirus and free-living amoebae. Rotavirus was present in 35% of the water samples collected from water filtration plants; however, domestic tap water samples had a prevalence of only 5%. Out of 20 water samples from filtration plants, 13 (65% were positive for Acanthamoeba spp., and one (5% was positive for B. mandrillaris. Out of 20 drinking water samples collected from different areas of Karachi, 35% were positive for Acanthamoeba spp. Rotavirus was detected in 5% of the drinking water samples tested. Overall, these findings showed for the first time the presence of rotavirus, in addition to pathogenic free-living amoebae in drinking water supplies of Karachi that could be an important public health risk for the affected population.

  17. Genome sequence of Rickettsia bellii illuminates the role of amoebae in gene exchanges between intracellular pathogens.

    Directory of Open Access Journals (Sweden)

    Hiroyuki Ogata

    2006-05-01

    Full Text Available The recently sequenced Rickettsia felis genome revealed an unexpected plasmid carrying several genes usually associated with DNA transfer, suggesting that ancestral rickettsiae might have been endowed with a conjugation apparatus. Here we present the genome sequence of Rickettsia bellii, the earliest diverging species of known rickettsiae. The 1,552,076 base pair-long chromosome does not exhibit the colinearity observed between other rickettsia genomes, and encodes a complete set of putative conjugal DNA transfer genes most similar to homologues found in Protochlamydia amoebophila UWE25, an obligate symbiont of amoebae. The genome exhibits many other genes highly similar to homologues in intracellular bacteria of amoebae. We sought and observed sex pili-like cell surface appendages for R. bellii. We also found that R. bellii very efficiently multiplies in the nucleus of eukaryotic cells and survives in the phagocytic amoeba, Acanthamoeba polyphaga. These results suggest that amoeba-like ancestral protozoa could have served as a genetic "melting pot" where the ancestors of rickettsiae and other bacteria promiscuously exchanged genes, eventually leading to their adaptation to the intracellular lifestyle within eukaryotic cells.

  18. Evaluating the use of testate amoebae for palaeohydrological reconstruction in permafrost peatlands

    DEFF Research Database (Denmark)

    Swindles, Graeme T.; Amesbury, Matthew J.; Turner, T. Edward

    2015-01-01

    The melting of high-latitude permafrost peatlands is a major concern due to a potential positive feedback on global climate change. We examine the ecology of testate amoebae in permafrost peatlands, based on sites in Sweden (similar to 200 km north of the Arctic Circle). Multivariate statistical ...

  19. Amoebae as potential environmental hosts for Mycobacterium ulcerans and other mycobacteria, but doubtful actors in Buruli ulcer epidemiology.

    Science.gov (United States)

    Gryseels, Sophie; Amissah, Diana; Durnez, Lies; Vandelannoote, Koen; Leirs, Herwig; De Jonckheere, Johan; Silva, Manuel T; Portaels, Françoise; Ablordey, Anthony; Eddyani, Miriam

    2012-01-01

    The reservoir and mode of transmission of Mycobacterium ulcerans, the causative agent of Buruli ulcer, remain unknown. Ecological, genetic and epidemiological information nonetheless suggests that M. ulcerans may reside in aquatic protozoa. We experimentally infected Acanthamoeba polyphaga with M. ulcerans and found that the bacilli were phagocytised, not digested and remained viable for the duration of the experiment. Furthermore, we collected 13 water, 90 biofilm and 45 detritus samples in both Buruli ulcer endemic and non-endemic communities in Ghana, from which we cultivated amoeboid protozoa and mycobacteria. M. ulcerans was not isolated, but other mycobacteria were as frequently isolated from intracellular as from extracellular sources, suggesting that they commonly infect amoebae in nature. We screened the samples as well as the amoeba cultures for the M. ulcerans markers IS2404, IS2606 and KR-B. IS2404 was detected in 2% of the environmental samples and in 4% of the amoeba cultures. The IS2404 positive amoeba cultures included up to 5 different protozoan species, and originated both from Buruli ulcer endemic and non-endemic communities. This is the first report of experimental infection of amoebae with M. ulcerans and of the detection of the marker IS2404 in amoeba cultures isolated from the environment. We conclude that amoeba are potential natural hosts for M. ulcerans, yet remain sceptical about their implication in the transmission of M. ulcerans to humans and their importance in the epidemiology of Buruli ulcer.

  20. Amoebae as potential environmental hosts for Mycobacterium ulcerans and other mycobacteria, but doubtful actors in Buruli ulcer epidemiology.

    Directory of Open Access Journals (Sweden)

    Sophie Gryseels

    Full Text Available The reservoir and mode of transmission of Mycobacterium ulcerans, the causative agent of Buruli ulcer, remain unknown. Ecological, genetic and epidemiological information nonetheless suggests that M. ulcerans may reside in aquatic protozoa.We experimentally infected Acanthamoeba polyphaga with M. ulcerans and found that the bacilli were phagocytised, not digested and remained viable for the duration of the experiment. Furthermore, we collected 13 water, 90 biofilm and 45 detritus samples in both Buruli ulcer endemic and non-endemic communities in Ghana, from which we cultivated amoeboid protozoa and mycobacteria. M. ulcerans was not isolated, but other mycobacteria were as frequently isolated from intracellular as from extracellular sources, suggesting that they commonly infect amoebae in nature. We screened the samples as well as the amoeba cultures for the M. ulcerans markers IS2404, IS2606 and KR-B. IS2404 was detected in 2% of the environmental samples and in 4% of the amoeba cultures. The IS2404 positive amoeba cultures included up to 5 different protozoan species, and originated both from Buruli ulcer endemic and non-endemic communities.This is the first report of experimental infection of amoebae with M. ulcerans and of the detection of the marker IS2404 in amoeba cultures isolated from the environment. We conclude that amoeba are potential natural hosts for M. ulcerans, yet remain sceptical about their implication in the transmission of M. ulcerans to humans and their importance in the epidemiology of Buruli ulcer.

  1. Osmotic second virial cross coefficients for star and linear polystyrenes

    International Nuclear Information System (INIS)

    Striolo, Alberto; Prausnitz, John M.

    2000-01-01

    Experimental osmotic second virial cross coefficients are reported for linear and 8-arm star polystyrenes in three solvents: toluene, cyclohexane, and methylcyclohexane. The osmotic second virial cross coefficient for 8-arm star and linear polystyrene is always positive and within the osmotic second virial coefficients measured for the single polymers. The positive cross coefficient indicates net repulsion between the two different polymers in dilute solution. The extent of repulsion is greatest in toluene and least in cyclohexane. To relate the macroscopic second virial coefficient to microscopic interactions, the potential of mean force between linear and 6-arm star polymers was computed by molecular simulation. The interaction between nonbonded polymer segments is given by a square-well potential. Well width was set equal to one half of the segment diameter. Different solvent conditions were investigated by using different well depths. Potentials of mean force were then used to compute the osmotic second virial cross coefficients. (c) 2000 American Institute of Physics

  2. Efficiency of Osmotic Dehydration of Apples in Polyols Solutions

    Directory of Open Access Journals (Sweden)

    Joanna Cichowska

    2018-02-01

    Full Text Available The present study aimed to evaluate the influence of selected compounds from the polyol group, as well as other saccharides, on the osmotic dehydration process of apples. The following alternative solutions were examined: erythritol, xylitol, maltitol, inulin and oligofructose. Efficiency of the osmotic dehydration process was evaluated based on the kinetics of the process, and through comparison of the results obtained during the application of a sucrose solution. This innovative research utilizes alternative solutions in osmotic pretreatment, which until now, have not been commonly used in fruit processing by researchers worldwide. Results indicate that erythritol and xylitol show stronger or similar efficiency to sucrose; however, the use of inulin, as well as oligofructose, was not satisfactory due to the insufficient, small osmotic driving forces of the process, and the low values of mass transfer parameters.

  3. Method of osmotic energy harvesting using responsive compounds and molecules

    KAUST Repository

    Hu, Xiao

    2017-07-27

    The present invention discloses and claims a more efficient and economical method and system for osmotic energy production and capture using responsive compounds and molecules. The present invention is an energy harvest system enabled by stimuli responsive draw solutions that are competent in terms of energy production, geographic location flexibility, and the affordable, efficient and economical production and delivery of osmotic power. Specifically, the present invention is a novel osmotic power system that uses stimuli responsive draw solutions, economically feasible larger permeable membranes, and low grade heat sources to deliver osmotic power more efficiently and economically with less negative environmental impact, greater power output, and located in more geographically diverse areas of the world than previously thought possible for supporting such a power source.

  4. Osmotic stress tolerance in semi-terrestrial tardigrades

    DEFF Research Database (Denmark)

    Heidemann, Nanna W T; Smith, Daniel K.; Hygum, Thomas L.

    2016-01-01

    Little is known about ionic and osmotic stress tolerance in tardigrades. Here, we examine salt stress tolerance in Ramazzottius oberhaeuseri and Echiniscus testudo from Nivå (Denmark) and address whether limno-terrestrial tardigrades can enter a state of quiescence (osmobiosis) in the face of hig...... that the limno-terrestrial R. oberhaeuseri enters a state of quiescence in the face of high external osmotic pressure and that it, in this state, is highly tolerant of ionic and osmotic stress.......Little is known about ionic and osmotic stress tolerance in tardigrades. Here, we examine salt stress tolerance in Ramazzottius oberhaeuseri and Echiniscus testudo from Nivå (Denmark) and address whether limno-terrestrial tardigrades can enter a state of quiescence (osmobiosis) in the face of high...

  5. Efficiency of Osmotic Dehydration of Apples in Polyols Solutions.

    Science.gov (United States)

    Cichowska, Joanna; Żubernik, Joanna; Czyżewski, Jakub; Kowalska, Hanna; Witrowa-Rajchert, Dorota

    2018-02-17

    The present study aimed to evaluate the influence of selected compounds from the polyol group, as well as other saccharides, on the osmotic dehydration process of apples. The following alternative solutions were examined: erythritol, xylitol, maltitol, inulin and oligofructose. Efficiency of the osmotic dehydration process was evaluated based on the kinetics of the process, and through comparison of the results obtained during the application of a sucrose solution. This innovative research utilizes alternative solutions in osmotic pretreatment, which until now, have not been commonly used in fruit processing by researchers worldwide. Results indicate that erythritol and xylitol show stronger or similar efficiency to sucrose; however, the use of inulin, as well as oligofructose, was not satisfactory due to the insufficient, small osmotic driving forces of the process, and the low values of mass transfer parameters.

  6. Physiological and genetic responses of bacteria to osmotic stress.

    OpenAIRE

    Csonka, L N

    1989-01-01

    The capacity of organisms to respond to fluctuations in their osmotic environments is an important physiological process that determines their abilities to thrive in a variety of habitats. The primary response of bacteria to exposure to a high osmotic environment is the accumulation of certain solutes, K+, glutamate, trehalose, proline, and glycinebetaine, at concentrations that are proportional to the osmolarity of the medium. The supposed function of these solutes is to maintain the osmolar...

  7. Osmotic and stimulant laxatives for the management of childhood constipation

    OpenAIRE

    Gordon, Morris; Macdonald, John; Parker, Claire; Akobeng, Anthony; Thomas, Adrian

    2016-01-01

    Background\\ud \\ud Constipation within childhood is an extremely common problem. Despite the widespread use of osmotic and stimulant laxatives by health professionals to manage constipation in children, there has been a long standing paucity of high quality evidence to support this practice.\\ud \\ud \\ud Objectives\\ud \\ud We set out to evaluate the efficacy and safety of osmotic and stimulant laxatives used to treat functional childhood constipation.\\ud \\ud \\ud Search methods\\ud \\ud We searched ...

  8. A physiological evaluation of the enhanced osmotic stress tolerance ...

    African Journals Online (AJOL)

    ELO

    2012-01-05

    Jan 5, 2012 ... (approximately 20°C). Leaf osmotic potential. Leaf osmotic potential (Ψleaf) was measured using a vapour pressure osmometer (Wescor, Model 5520). The sample was held at -20°C for at least 3 h in a 1.5 ml tube, thawed for 30 min at room temperature and squashed to extract the sap (Clifford et al., 1998).

  9. Experimental Support for a Predictive Osmotic Model of Clay Membranes

    International Nuclear Information System (INIS)

    Fritz, S.J.

    2001-01-01

    Osmosis has been cited as a mechanism for explaining anomalously high fluid pressures in the subsurface. Clays and shales act as membranes, and osmotic flux across these units may result in pressures sufficiently high to explain these anomalies. The theoretical osmotic pressures as calculated solely from solution properties can be quite large; however, it is not yet resolved whether these geologic membranes are sufficiently ideal to generate such pressures

  10. Osmotic pressure in a bacterial swarm.

    Science.gov (United States)

    Ping, Liyan; Wu, Yilin; Hosu, Basarab G; Tang, Jay X; Berg, Howard C

    2014-08-19

    Using Escherichia coli as a model organism, we studied how water is recruited by a bacterial swarm. A previous analysis of trajectories of small air bubbles revealed a stream of fluid flowing in a clockwise direction ahead of the swarm. A companion study suggested that water moves out of the agar into the swarm in a narrow region centered ∼ 30 μm from the leading edge of the swarm and then back into the agar (at a smaller rate) in a region centered ∼ 120 μm back from the leading edge. Presumably, these flows are driven by changes in osmolarity. Here, we utilized green/red fluorescent liposomes as reporters of osmolarity to verify this hypothesis. The stream of fluid that flows in front of the swarm contains osmolytes. Two distinct regions are observed inside the swarm near its leading edge: an outer high-osmolarity band (∼ 30 mOsm higher than the agar baseline) and an inner low-osmolarity band (isotonic or slightly hypotonic to the agar baseline). This profile supports the fluid-flow model derived from the drift of air bubbles and provides new (to our knowledge) insights into water maintenance in bacterial swarms. High osmotic pressure at the leading edge of the swarm extracts water from the underlying agar and promotes motility. The osmolyte is of high molecular weight and probably is lipopolysaccharide. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  11. Seasonal abundances of naked amoebae in biofilms on shells of zebra mussels (Dreissena polymorpha) with comparative data from rock scrapings.

    Science.gov (United States)

    Bischoff, Paul J; Wetmore, Scott

    2009-01-01

    In North America, zebra mussels (Dreissena polymorpha) are notoriously known as invasive species. The abundance of naked amoebae sampled from the shells of zebra mussels was compared with abundances from rock scrapings at approximately monthly intervals for 1 year. The sites were 2 km apart along the same shoreline. No significant difference in abundance of naked amoebae (F = 1.44; P amoebae in winter, followed by peaks in early spring. The percent encysted increased from a low of 1% in the summer to 80% in early winter.

  12. Collisionless electrostatic shocks

    DEFF Research Database (Denmark)

    Andersen, H.K.; Andersen, S.A.; Jensen, Vagn Orla

    1970-01-01

    An attempt was made in the laboratory to observe the standing collisionless electrostatic shocks in connection with the bow shock of the earth......An attempt was made in the laboratory to observe the standing collisionless electrostatic shocks in connection with the bow shock of the earth...

  13. Acidic pH shock induces the expressions of a wide range of stress-response genes

    Directory of Open Access Journals (Sweden)

    Hong Soon-Kwang

    2008-12-01

    Full Text Available Abstract Background Environmental signals usually enhance secondary metabolite production in Streptomycetes by initiating complex signal transduction system. It is known that different sigma factors respond to different types of stresses, respectively in Streptomyces strains, which have a number of unique signal transduction mechanisms depending on the types of environmental shock. In this study, we wanted to know how a pH shock would affect the expression of various sigma factors and shock-related proteins in S. coelicolor A3(2. Results According to the results of transcriptional and proteomic analyses, the major number of sigma factor genes were upregulated by an acidic pH shock. Well-studied sigma factor genes of sigH (heat shock, sigR (oxidative stress, sigB (osmotic shock, and hrdD that play a major role in the secondary metabolism, were all strongly upregulated by the pH shock. A number of heat shock proteins including the DnaK family and chaperones such as GroEL2 were also observed to be upregulated by the pH shock, while their repressor of hspR was strongly downregulated. Oxidative stress-related proteins such as thioredoxin, catalase, superoxide dismutase, peroxidase, and osmotic shock-related protein such as vesicle synthases were also upregulated in overall. Conclusion From these observations, an acidic pH shock was considered to be one of the strongest stresses to influence a wide range of sigma factors and shock-related proteins including general stress response proteins. The upregulation of the sigma factors and shock proteins already found to be related to actinorhodin biosynthesis was considered to have contributed to enhanced actinorhodin productivity by mediating the pH shock signal to regulators or biosynthesis genes for actinorhodin production.

  14. Osmotic Compounds Enhance Antibiotic Efficacy against Acinetobacter baumannii Biofilm Communities.

    Science.gov (United States)

    Falghoush, Azeza; Beyenal, Haluk; Besser, Thomas E; Omsland, Anders; Call, Douglas R

    2017-10-01

    Biofilm-associated infections are a clinical challenge, in part because a hydrated matrix protects the bacterial community from antibiotics. Herein, we evaluated how different osmotic compounds (maltodextrin, sucrose, and polyethylene glycol [PEG]) enhance antibiotic efficacy against Acinetobacter baumannii biofilm communities. Established (24-h) test tube biofilms (strain ATCC 17978) were treated with osmotic compounds in the presence or absence of 10× the MIC of different antibiotics (50 μg/ml tobramycin, 20 μg/ml ciprofloxacin, 300 μg/ml chloramphenicol, 30 μg/ml nalidixic acid, or 100 μg/ml erythromycin). Combining antibiotics with hypertonic concentrations of the osmotic compounds for 24 h reduced the number of biofilm bacteria by 5 to 7 log ( P baumannii strains were similarly treated with 400-Da PEG and tobramycin, resulting in a mean 2.7-log reduction in recoverable bacteria compared with tobramycin treatment alone. Multivariate regression models with data from different osmotic compounds and nine antibiotics demonstrated that the benefit from combining hypertonic treatments with antibiotics is a function of antibiotic mass and lipophilicity ( r 2 > 0.82; P baumannii and Escherichia coli K-12. Augmenting topical antibiotic therapies with a low-mass hypertonic treatment may enhance the efficacy of antibiotics against wound biofilms, particularly when using low-mass hydrophilic antibiotics. IMPORTANCE Biofilms form a barrier that protects bacteria from environmental insults, including exposure to antibiotics. We demonstrated that multiple osmotic compounds can enhance antibiotic efficacy against Acinetobacter baumannii biofilm communities, but viscosity is a limiting factor, and the most effective compounds have lower molecular mass. The synergism between osmotic compounds and antibiotics is also dependent on the hydrophobicity and mass of the antibiotics. The statistical models presented herein provide a basis for predicting the optimal combination of

  15. [A study on the taxonomy of soil amoebas from Caspian plague foci based on an analysis of ribosomal operon sequences].

    Science.gov (United States)

    Koshel', E I; Anisimova, L V; Novichkova, L A; Vidiaeva, N A; Guseva, N P; Eroshenko, G A; Kutyrev, V V

    2015-01-01

    The results of a study on the taxonomy and quantitative abundance of free-living amoebas in soil samples from the Russian plague foci of the northwestern Caspian steppe, the Caspian sand, and the Volga-Ural steppe are presented. Amoebas of the Willaertia and Hartmanella genera, as well as representatives of myxomycetes, were isolated from samples. From these, amoebas of the Acanthamoeba genus predominated and could be as abundantas 300000 cells per 1 g of soil. Sequencing of the 18S rRNA gene region showed that Acanthamoeba from the Volga-Ural steppe focus belonged to the A. castellanii species. Phylogenetic analysis confirmed that amoebas from two other Caspian foci belonged to the species of Acanthamoeba spp.

  16. Survival of Campylobacter jejuni in co-culture with Acanthamoeba castellanii: role of amoeba-mediated depletion of dissolved oxygen

    DEFF Research Database (Denmark)

    Bui, Thanh Xuan; Winding, Anne; Qvortrup, Klaus

    2012-01-01

    of intracellular C. jejuni in A. castellanii 5 h post gentamicin treatment at 25°C. Conversely, we found that A. castellanii promoted the extracellular growth of C. jejuni in co-cultures at 37°C in aerobic conditions. This growth-promoting effect did not require amoebae – bacteria contact. The growth rates......, the dissolved oxygen levels of co-cultures with or without amoebae – bacteria contact were much lower than those observed with culture media or with C. jejuni alone incubated in aerobic conditions, and were comparable with levels obtained after 24 h of growth of C. jejuni under microaerophilic conditions. Our...... observed with or without contact with amoeba were similar to those observed when C. jejuni was grown in microaerophilic conditions. Preconditioned media prepared with live or dead amoebae cultivated with or without C. jejuni did not promote the growth of C. jejuni in aerobic conditions. Interestingly...

  17. Presence of pathogenic amoebae in power plant cooling waters. Final report, October 15, 1977-September 30, 1979. [Naegleria fowleri

    Energy Technology Data Exchange (ETDEWEB)

    Tyndall, R.L.; Willaert, E.; Stevens, A.R.

    1981-03-01

    Cooling-water-associated algae and sediments from five northern and five southern or western electric power plants were tested for the presence of pathogenic amoebae. In addition, water algae and sediments from five northern and five southern/western sites not associated with power plants were tested. There was a significant correlation at northern power plants between the presence of thermophilic, pathogenic amoebae in cooling waters and thermal additions. Presence of the pathogenic did not correlate with salinity, pH, conductivity, or a variety of various chemical components of the cooling waters. Selected pathogenic isolates were tested serologically and were classified as Naegleria fowleri. Although thermal additions were shown to be contributing factor in predisposing cooling waters to the growth of pathogenic amoebae, the data suggest the involvement of other currently undefined parameters associated with the presence of the pathogenic amoebae. 35 refs., 21 tabs.

  18. Detection and identification of free-living amoeba from aquatic environment in different seasons in Taiwan

    Science.gov (United States)

    Tzeng, K.; Hsu, B.; Tsai, H.; Huang, P.; Tsai, J.; Kao, P.; Huang, K.; Chen, J.

    2013-12-01

    Free-living amoeba includes Acanthamoeba and Naegleria, which are widely distributed in water and soil. Human infection with free-living amoeba leads to serious illness, even lethal. For example, central nervous system infection will cause amoebic meningoencephalitis, and infections will cause amoebic keratitis. The presence of free-living amoeba in environment water can be used as a water quality indicator in ecosystem assessment. In Taiwan, reservoirs are indispensable because of the water source are limited by the steep terrain and the short river flow. Therefore, we need to pay more attention in the quality control of reservoirs water. The aims of this study are to investigate the presence of free-living amoeba in Taiwan reservoirs, and to compare the differences among seasons. At last, the identification and genotyping of Acanthamoeba and Naegleria are investigated. In this study, we use polymerase chain reaction with specific primers to analyze the presence of free-living amoeba in aquatic environment. We collected total 60 samples from reservoirs in Taiwan. The water samples are divided into two parts for both direct concentration method and culture method. The results show the different detection rates among seasons. For Acanthamoeba, the detection rates were 28.3% (17 of 60 water samples), 21.7% (13 of 60 water samples) and 8.3% (5 of 60 water samples) in autumn, winter and spring, respectively. For Naegleria, the detection rates were 6.7% (4 of 60 water samples), 0% (0 of 60 water samples) and 0% (0 of 60 water samples) were detected positive in autumn, winter and spring, respectively. Sequence analysis showed that the major genotypes in Acanthamoeba were T3, T4, T10 and T11 in autumn, T2, T4 and T10 in winter, T4 in spring. Due to the presences of Acanthamoeba and Naegleria in reservoirs, we should pay more attention in water quality monitoring to prevent the potential risks of diseases. Keywords: free-living amoeba, Acanthamoeba, Naegleria, polymerase

  19. Geometrical shock dynamics for magnetohydrodynamic fast shocks

    KAUST Repository

    Mostert, W.

    2016-12-12

    We describe a formulation of two-dimensional geometrical shock dynamics (GSD) suitable for ideal magnetohydrodynamic (MHD) fast shocks under magnetic fields of general strength and orientation. The resulting area–Mach-number–shock-angle relation is then incorporated into a numerical method using pseudospectral differentiation. The MHD-GSD model is verified by comparison with results from nonlinear finite-volume solution of the complete ideal MHD equations applied to a shock implosion flow in the presence of an oblique and spatially varying magnetic field ahead of the shock. Results from application of the MHD-GSD equations to the stability of fast MHD shocks in two dimensions are presented. It is shown that the time to formation of triple points for both perturbed MHD and gas-dynamic shocks increases as (Formula presented.), where (Formula presented.) is a measure of the initial Mach-number perturbation. Symmetry breaking in the MHD case is demonstrated. In cylindrical converging geometry, in the presence of an azimuthal field produced by a line current, the MHD shock behaves in the mean as in Pullin et al. (Phys. Fluids, vol. 26, 2014, 097103), but suffers a greater relative pressure fluctuation along the shock than the gas-dynamic shock. © 2016 Cambridge University Press

  20. Evidence of test detachment in Astrorhiza limicola and two consequential synonyms: Amoeba gigantea and Megamoebomyxa argillobia (Foraminiferida)

    DEFF Research Database (Denmark)

    Cedhagen, Tomas; Tendal, Ole S.

    1989-01-01

    Laboratory observations and experiments demonstrate that the naked rhizopods Amoeba gigantea SANDAHL, 1857 and Megamoebomyxa argillo~ia NYHOLM, 1950, and the foraminifers Astrorhiza arenifera STSCHEDRlNA, 1946, A. sabulifera STSCHEDRINA, 1946 and A. arctlca STSCHEDRINA, 1958 are synonyms of Astro......Laboratory observations and experiments demonstrate that the naked rhizopods Amoeba gigantea SANDAHL, 1857 and Megamoebomyxa argillo~ia NYHOLM, 1950, and the foraminifers Astrorhiza arenifera STSCHEDRlNA, 1946, A. sabulifera STSCHEDRINA, 1946 and A. arctlca STSCHEDRINA, 1958 are synonyms...

  1. Seasonal distribution of air-borne pathogenic and free-living amoebae in Mexico City and its suburbs

    Energy Technology Data Exchange (ETDEWEB)

    Rivera, F.; Bonilla, P.; Ramirez, E.; Calderon, A.; Gallegos, E.; Rodriguez, S.; Ortiz, R.; Hernandez, D.; Rivera, V. (ENEP-Iztacala, Tlalnepantla (Mexico). Lab. of Environmental Microbiology)

    1994-03-01

    A survey was carried out over a one-year period to isolate amoebae suspended in the air of Mexico City and its suburbs. Sampling stations were placed at the four cardinal points of the metropolitan area. Selective media were used to culture the amoebae isolated. Specialized taxonomic keys and physical and physiological tests were used for identification, and a statistical analysis was performed to determine the correlations between physico-chemical and biological parameters. 108 strains were isolated, of which 19 were pathogenic via intracerebral inoculation and 9 via intranasal inoculation. Species of the genera Acanthamoeba, Vahlkampfia and Hartmannella were most abundant. Acanthamoeba polyphaga showed the highest abundance. Several times during the period of the study SO[sub 2], O[sub 3], CO NO and NO[sub 2] exceeded the permissible levels established by the Mexican government. The ability of amoebae to form cysts and cyst size were important factors for their presence, survival, abundance and diversity in the atmosphere. The main source of air-borne amoebae was the soil. Factors that favored the incidence and diversity of the isolates were wind speed and direction, low relative humidity, generation of frequent dust-storms, resuspension of amoebae by vehicular traffic, proximity to garbage dumps and large extensions of bare soil. Soil cover was a factor associated with a reduction in the incidence and diversity of the aerial amoebae. This study demonstrates that there are viable cysts of amoebae in the atmosphere of Mexico City, that may have potential importance in the case of certain kinds of human allergies and diseases. Further research is needed to find out the aerial presence of viable cysts of obligatory, amphizoic or opportunistic amoebic parasites, and to clarify the qualitative and quantitative effects of the local meteorological and physico-chemical environment on the free-living amoebae present in the atmosphere. 48 refs., 11 figs., 4 tabs.

  2. Drying and osmotic conditioning in Hancornia speciosa Gomes seeds

    Directory of Open Access Journals (Sweden)

    Tathiana Elisa Masetto

    Full Text Available Hancornia speciosa is a native tree species of the Brazilian Cerrado whose seeds are desiccation sensitive. In this study, we aimed to evaluate drying and osmotic conditioning in H. speciosa seeds. We used fresh seeds with 48% moisture content, which were slowly dried until they attained contents of 20%, 15%, 10% and 5%. To evaluate osmotic conditioning, the seeds were imbibed in 12 mL osmotic solutions at 0.0; -0.2; -0.4 and -0.6 MPa for two days. After that, they were dehydrated until their original moisture content. The experiments were carried out in a completely randomized design with four repetitions with 50 seeds each. Reduction in moisture content from 20% to 5% decreased the physiological potential of seeds. H. speciosa seeds do not require osmotic priming with PEG solutions, because imbibition of seeds in osmotic solutions of up to -0.6 MPa results in reduction of germination rate and seedling length.

  3. Quantification of osmotic water transport in vivo using fluorescent albumin.

    Science.gov (United States)

    Morelle, Johann; Sow, Amadou; Vertommen, Didier; Jamar, François; Rippe, Bengt; Devuyst, Olivier

    2014-10-15

    Osmotic water transport across the peritoneal membrane is applied during peritoneal dialysis to remove the excess water accumulated in patients with end-stage renal disease. The discovery of aquaporin water channels and the generation of transgenic animals have stressed the need for novel and accurate methods to unravel molecular mechanisms of water permeability in vivo. Here, we describe the use of fluorescently labeled albumin as a reliable indicator of osmotic water transport across the peritoneal membrane in a well-established mouse model of peritoneal dialysis. After detailed evaluation of intraperitoneal tracer mass kinetics, the technique was validated against direct volumetry, considered as the gold standard. The pH-insensitive dye Alexa Fluor 555-albumin was applied to quantify osmotic water transport across the mouse peritoneal membrane resulting from modulating dialysate osmolality and genetic silencing of the water channel aquaporin-1 (AQP1). Quantification of osmotic water transport using Alexa Fluor 555-albumin closely correlated with direct volumetry and with estimations based on radioiodinated ((125)I) serum albumin (RISA). The low intraperitoneal pressure probably accounts for the negligible disappearance of the tracer from the peritoneal cavity in this model. Taken together, these data demonstrate the appropriateness of pH-insensitive Alexa Fluor 555-albumin as a practical and reliable intraperitoneal volume tracer to quantify osmotic water transport in vivo. Copyright © 2014 the American Physiological Society.

  4. Structure and osmotic pressure of ionic microgel dispersions

    International Nuclear Information System (INIS)

    Hedrick, Mary M.; Chung, Jun Kyung; Denton, Alan R.

    2015-01-01

    We investigate structural and thermodynamic properties of aqueous dispersions of ionic microgels—soft colloidal gel particles that exhibit unusual phase behavior. Starting from a coarse-grained model of microgel macroions as charged spheres that are permeable to microions, we perform simulations and theoretical calculations using two complementary implementations of Poisson-Boltzmann (PB) theory. Within a one-component model, based on a linear-screening approximation for effective electrostatic pair interactions, we perform molecular dynamics simulations to compute macroion-macroion radial distribution functions, static structure factors, and macroion contributions to the osmotic pressure. For the same model, using a variational approximation for the free energy, we compute both macroion and microion contributions to the osmotic pressure. Within a spherical cell model, which neglects macroion correlations, we solve the nonlinear PB equation to compute microion distributions and osmotic pressures. By comparing the one-component and cell model implementations of PB theory, we demonstrate that the linear-screening approximation is valid for moderately charged microgels. By further comparing cell model predictions with simulation data for osmotic pressure, we chart the cell model’s limits in predicting osmotic pressures of salty dispersions

  5. Arbuscular mycorrhiza effects on plant performance under osmotic stress.

    Science.gov (United States)

    Santander, Christian; Aroca, Ricardo; Ruiz-Lozano, Juan Manuel; Olave, Jorge; Cartes, Paula; Borie, Fernando; Cornejo, Pablo

    2017-10-01

    At present, drought and soil salinity are among the most severe environmental stresses that affect the growth of plants through marked reduction of water uptake which lowers water potential, leading to osmotic stress. In general, osmotic stress causes a series of morphological, physiological, biochemical, and molecular changes that affect plant performance. Several studies have found that diverse types of soil microorganisms improve plant growth, especially when plants are under stressful conditions. Most important are the arbuscular mycorrhizal fungi (AMF) which form arbuscular mycorrhizas (AM) with approximately 80% of plant species and are present in almost all terrestrial ecosystems. Beyond the well-known role of AM in improving plant nutrient uptake, the contributions of AM to plants coping with osmotic stress merit analysis. With this review, we describe the principal direct and indirect mechanisms by which AM modify plant responses to osmotic stress, highlighting the role of AM in photosynthetic activity, water use efficiency, osmoprotectant production, antioxidant activities, and gene expression. We also discuss the potential for using AMF to improve plant performance under osmotic stress conditions and the lines of research needed to optimize AM use in plant production.

  6. Accumulation of Stable Full-Length Circular Group I Intron RNAs during Heat-Shock

    DEFF Research Database (Denmark)

    Andersen, Kasper L.; Beckert, Bertrand; Masquida, Benoit

    2016-01-01

    Group I introns in nuclear ribosomal RNA of eukaryotic microorganisms are processed by splicing or circularization. The latter results in formation of full-length circular introns without ligation of the exons and has been proposed to be active in intron mobility. We applied qRT-PCR to estimate...... the copy number of circular intron RNA from the myxomycete Didymium iridis. In exponentially growing amoebae, the circular introns are nuclear and found in 70 copies per cell. During heat-shock, the circular form is up-regulated to more than 500 copies per cell. The intron harbours two ribozymes that have...

  7. Free-Living Amoebae as Hosts for and Vectors of Intracellular Microorganisms with Public Health Significance

    Science.gov (United States)

    Balczun, Carsten; Scheid, Patrick L.

    2017-01-01

    Free-living amoebae (FLA) are parasites within both humans and animals causing a wide range of symptoms and act as hosts of, and vehicles for phylogenetically diverse microorganisms, called endocytobionts. The interaction of the FLA with sympatric microorganisms leads to an exceptional diversity within FLA. Some of these bacteria, viruses, and even eukaryotes, can live and replicate intracellularly within the FLA. This relationship provides protection to the microorganisms from external interventions and a dispersal mechanism across various habitats. Among those intracellularly-replicating or -residing organisms there are obligate and facultative pathogenic microorganisms affecting the health of humans or animals and are therefore of interest to Public Health Authorities. Mimiviruses, Pandoraviruses, and Pithoviruses are examples for interesting viral endocytobionts within FLA. Future research is expected to reveal further endocytobionts within free-living amoebae and other protozoa through co-cultivation studies, genomic, transcriptomic, and proteomic analyses. PMID:28368313

  8. Reconstruction of active regular motion in amoeba extract: dynamic cooperation between sol and gel states.

    Directory of Open Access Journals (Sweden)

    Yukinori Nishigami

    Full Text Available Amoeboid locomotion is one of the typical modes of biological cell migration. Cytoplasmic sol-gel conversion of an actomyosin system is thought to play an important role in locomotion. However, the mechanisms underlying sol-gel conversion, including trigger, signal, and regulating factors, remain unclear. We developed a novel model system in which an actomyosin fraction moves like an amoeba in a cytoplasmic extract. Rheological study of this model system revealed that the actomyosin fraction exhibits shear banding: the sol-gel state of actomyosin can be regulated by shear rate or mechanical force. Furthermore, study of the living cell indicated that the shear-banding property also causes sol-gel conversion with the same order of magnitude as that of shear rate. Our results suggest that the inherent sol-gel transition property plays an essential role in the self-regulation of autonomous translational motion in amoeba.

  9. An intracellular replication niche for Vibrio cholerae in the amoeba Acanthamoeba castellanii.

    Science.gov (United States)

    Van der Henst, Charles; Scrignari, Tiziana; Maclachlan, Catherine; Blokesch, Melanie

    2016-04-01

    Vibrio cholerae is a human pathogen and the causative agent of cholera. The persistence of this bacterium in aquatic environments is a key epidemiological concern, as cholera is transmitted through contaminated water. Predatory protists, such as amoebae, are major regulators of bacterial populations in such environments. Therefore, we investigated the interaction between V. cholerae and the amoeba Acanthamoeba castellanii at the single-cell level. We observed that V. cholerae can resist intracellular killing. The non-digested bacteria were either released or, alternatively, established a replication niche within the contractile vacuole of A. castellanii. V. cholerae was maintained within this compartment even upon encystment. The pathogen ultimately returned to its aquatic habitat through lysis of A. castellanii, a process that was dependent on the production of extracellular polysaccharide by the pathogen. This study reinforces the concept that V. cholerae is a facultative intracellular bacterium and describes a new host-pathogen interaction.

  10. [Free-living amoebae: analytical methods for water and biofilm quality control].

    Science.gov (United States)

    Bonadonna, L; Lacchetti, I; Paradiso, R

    2006-01-01

    Free-living amoebae are ubiquitous. Some species can cause infections in humans and it is known that they can ingest and protect many microrganisms, such as species belonging to Legionella genus. Till now in Italy the environmental surveillance is still scarce because of both the lack of appropriate and promptly practical methods and drawbacks due to matrices characteristics. In the present study simple techniques were investigated and evaluated to detect and observe free-living amoebae in good water quality and biofilm samples. The membrane filtration technique for water analysis and the direct presence/absence technique for biofilm were recognized as workable methods, easily to be used also by laboratories with little skills and equipments.

  11. Engineering an artificial amoeba propelled by nanoparticle-triggered actin polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Yi Jinsoo; Schmidt, Jacob; Chien Aichi; Montemagno, Carlo D [Department of Bioengineering, University of California Los Angeles, 420 Westwood Plaza, 7523 Boelter Hall, Los Angeles, CA 90095-1600 (United States)], E-mail: montemcd@ucmail.uc.edu

    2009-02-25

    We have engineered an amoeba system combining nanofabricated inorganic materials with biological components, capable of propelling itself via actin polymerization. The nanofabricated materials have a mechanism similar to the locomotion of the Listeria monocytogenes, food poisoning bacteria. The propulsive force generation utilizes nanoparticles made from nickel and gold functionalized with the Listeria monocytogenes transmembrane protein, ActA. These Listeria-mimic nanoparticles were in concert with actin, actin binding proteins, ATP (adenosine triphosphate) and encapsulated within a lipid vesicle. This system is an artificial cell, such as a vesicle, where artificial nanobacteria and actin polymerization machinery are used in driving force generators inside the cell. The assembled structure was observed to crawl on a glass surface analogously to an amoeba, with the speed of the movement dependent on the amount of actin monomers and ATP present.

  12. Interactions Between Testate Amoebae and Saprotrophic Microfungi in a Scots Pine Litter Microcosm

    Czech Academy of Sciences Publication Activity Database

    Vohník, Martin; Burdíková, Zuzana; Vyhnal, Aleš; Koukol, O.

    2011-01-01

    Roč. 61, č. 3 (2011), s. 660-668 ISSN 0095-3628 R&D Projects: GA ČR GP206/09/P340; GA ČR(CZ) GD204/09/H084 Institutional research plan: CEZ:AV0Z50110509; CEZ:AV0Z60050516 Keywords : testate amoebae * saprotrophic fungi * litter Subject RIV: EF - Botanics Impact factor: 2.912, year: 2011

  13. Amoebae, Giant Viruses, and Virophages Make Up a Complex, Multilayered Threesome

    OpenAIRE

    Diesend, Jan; Kruse, Janis; Hagedorn, Monica; Hammann, Christian

    2018-01-01

    Viral infection had not been observed for amoebae, until the Acanthamoeba polyphaga mimivirus (APMV) was discovered in 2003. APMV belongs to the nucleocytoplasmatic large DNA virus (NCLDV) family and infects not only A. polyphaga, but also other professional phagocytes. Here, we review the Megavirales to give an overview of the current members of the Mimi- and Marseilleviridae families and their structural features during amoebal infection. We summarize the different steps of their infection ...

  14. An Amoeba/Zoozanthellae Consortium as a Model System for Animal/Algal Symbiosis

    Science.gov (United States)

    1991-06-18

    of the 9 isolates of Symbiodinium anthopleura which contained swimming small flagellates resistant to the antobiotics and too motile to be engulfed by...was used as a tool for 9 cies. The resistance of these unicellular algae to the amoe- cleaning these algae from digestible contaminating 0 bal... resistant to the antibiotics and the external contaminants but did ne, kill the algae protected tOO motile to be engulfed by the amoebae. inside the amoebal

  15. Water quality bioassay using selected protozoa. I. [Paramecium candatum; Amoeba proteus; Euglena gracilis

    Energy Technology Data Exchange (ETDEWEB)

    Mills, W.L.

    1976-01-01

    The suitability of certain species of protozoa as indicators of water quality has been determined. Experiments were conducted under laboratory conditions to standardize a bioassay procedure for water quality using either Paramecium caudatum, Amoeba proteus, or Euglena gracilis as the indicator organism. The bioassay, which consists of exposing the organisms to a known concentration of pollutant under laboratory conditions, followed by microscopic observation to establish the time of death, affords a reliable, convenient and inexpensive way to monitor for water quality.

  16. Ecology of Testate Amoebae in the Komořany Ponds in the Vltava Basin

    Czech Academy of Sciences Publication Activity Database

    Burdíková, Zuzana; Čapek, Martin; Švindrych, Zdeněk; Gryndler, M.; Kubínová, Lucie; Holcová, K.

    2012-01-01

    Roč. 64, č. 1 (2012), s. 117-130 ISSN 0095-3628 R&D Projects: GA MŠk(CZ) LC06063; GA ČR(CZ) GAP108/11/0794 Institutional research plan: CEZ:AV0Z50110509 Keywords : ecology * freshwater ecosystem * testate amoeba e * seasonal variability Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.277, year: 2012

  17. Phospholipids trigger Cryptococcus neoformans capsular enlargement during interactions with amoebae and macrophages.

    Directory of Open Access Journals (Sweden)

    Cara J Chrisman

    2011-05-01

    Full Text Available A remarkable aspect of the interaction of Cryptococcus neoformans with mammalian hosts is a consistent increase in capsule volume. Given that many aspects of the interaction of C. neoformans with macrophages are also observed with amoebae, we hypothesized that the capsule enlargement phenomenon also had a protozoan parallel. Incubation of C. neoformans with Acanthamoeba castellanii resulted in C. neoformans capsular enlargement. The phenomenon required contact between fungal and protozoan cells but did not require amoeba viability. Analysis of amoebae extracts showed that the likely stimuli for capsule enlargement were protozoan polar lipids. Extracts from macrophages and mammalian serum also triggered cryptococcal capsular enlargement. C. neoformans capsule enlargement required expression of fungal phospholipase B, but not phospholipase C. Purified phospholipids, in particular, phosphatidylcholine, and derived molecules triggered capsular enlargement with the subsequent formation of giant cells. These results implicate phospholipids as a trigger for both C. neoformans capsule enlargement in vivo and exopolysaccharide production. The observation that the incubation of C. neoformans with phospholipids led to the formation of giant cells provides the means to generate these enigmatic cells in vitro. Protozoan- or mammalian-derived polar lipids could represent a danger signal for C. neoformans that triggers capsular enlargement as a non-specific defense mechanism against potential predatory cells. Hence, phospholipids are the first host-derived molecules identified to trigger capsular enlargement. The parallels apparent in the capsular response of C. neoformans to both amoebae and macrophages provide additional support for the notion that certain aspects of cryptococcal virulence emerged as a consequence of environmental interactions with other microorganisms such as protists.

  18. Environmental Free-Living Amoebae Isolated from Soil in Khon Kaen, Thailand, Antagonize Burkholderia pseudomallei.

    Directory of Open Access Journals (Sweden)

    Parumon Noinarin

    Full Text Available Presence of Burkholderia pseudomallei in soil and water is correlated with endemicity of melioidosis in Southeast Asia and northern Australia. Several biological and physico-chemical factors have been shown to influence persistence of B. pseudomallei in the environment of endemic areas. This study was the first to evaluate the interaction of B. pseudomallei with soil amoebae isolated from B. pseudomallei-positive soil site in Khon Kaen, Thailand. Four species of amoebae, Paravahlkampfia ustiana, Acanthamoeba sp., Naegleria pagei, and isolate A-ST39-E1, were isolated, cultured and identified based on morphology, movement and 18S rRNA gene sequence. Co-cultivation combined with a kanamycin-protection assay of B. pseudomallei with these amoebae at MOI 20 at 30°C were evaluated during 0-6 h using the plate count technique on Ashdown's agar. The fate of intracellular B. pseudomallei in these amoebae was also monitored by confocal laser scanning microscopy (CLSM observation of the CellTracker™ Orange-B. pseudomallei stained cells. The results demonstrated the ability of P. ustiana, Acanthamoeba sp. and isolate A-ST39-E1 to graze B. pseudomallei. However, the number of internalized B. pseudomallei substantially decreased and the bacterial cells disappeared during the observation period, suggesting they had been digested. We found that B. pseudomallei promoted the growth of Acanthamoeba sp. and isolate A-ST39-E1 in co-cultures at MOI 100 at 30°C, 24 h. These findings indicated that P. ustiana, Acanthamoeba sp. and isolate A-ST39-E1 may prey upon B. pseudomallei rather than representing potential environmental reservoirs in which the bacteria can persist.

  19. Detection of antibody against limax amoebae by means of the indirect haemagglutination test.

    Science.gov (United States)

    Cerva, L

    1977-01-01

    A detailed description is given of the procuedure of the indirect haemagglutination test employed in the detection of specific antibodies against pathogenic amoebae of the genera Naegleria and Acanthamoeba. The preservation of all ingredients obtained by lyophilisation provide for a standard pattern of the test. The results of the test with experimentally prepared immune rabbit sera demonstrate an antigenic uniformity of the various isolates of Naegleria fowleri, and their marked difference from Acanthamoeba.

  20. Presence of Legionella and Free-Living Amoebae in Composts and Bioaerosols from Composting Facilities

    OpenAIRE

    Conza, Lisa; Pagani, Simona Casati; Gaia, Valeria

    2013-01-01

    Several species of Legionella cause Legionnaires' disease (LD). Infection may occur through inhalation of Legionella or amoebal vesicles. The reservoirs of Legionella are water, soil, potting soil and compost. Some species of free-living amoebae (FLA) that are naturally present in water and soil were described as hosts for Legionella. This study aimed to understand whether or not the composting facilities could be sources of community-acquired Legionella infections after development of bioaer...

  1. Folding propensity of intrinsically disordered proteins by osmotic stress

    International Nuclear Information System (INIS)

    Mansouri, Amanda L.; Grese, Laura N.; Rowe, Erica L.

    2016-01-01

    Proteins imparted with intrinsic disorder conduct a range of essential cellular functions. To better understand the folding and hydration properties of intrinsically disordered proteins (IDPs), we used osmotic stress to induce conformational changes in nuclear co-activator binding domain (NCBD) and activator for thyroid hormone and retinoid receptor (ACTR). Osmotic stress was applied by the addition of small and polymeric osmolytes, where we discovered that water contributions to NCBD folding always exceeded those for ACTR. Both NCBD and ACTR were found to gain a-helical structure with increasing osmotic stress, consistent with their folding upon NCBD/ACTR complex formation. Using small-angle neutron scattering (SANS), we further characterized NCBD structural changes with the osmolyte ethylene glycol. Here a large reduction in overall size initially occurred before substantial secondary structural change. In conclusion, by focusing on folding propensity, and linked hydration changes, we uncover new insights that may be important for how IDP folding contributes to binding.

  2. Studies of Protein Solution Properties Using Osmotic Pressure Measurements

    Science.gov (United States)

    Agena, S.; Bogle, David; Pusey, Marc; Agena, S.

    1998-01-01

    Examination of the protein crystallization process involves investigation of the liquid and solid state and a protein's properties in these states. Liquid state studies such as protein self association in solution by light scattering methods or other methods have been used to examine a protein Is properties and therefore its crystallization process and conditions. Likewise can osmotic pressure data be used to examine protein properties and various published osmotic pressure studies were examined by us to correlate osmotic pressure to protein solution properties. The solution behavior of serum albumin, alpha - chymotrypsin, beta - lactoglobulin and ovalbumin was examined over a range of temperatures, pH values and different salt types and concentrations. Using virial expansion and a local composition model the non ideal solution behavior in form of the activity coefficients (thermodynamic) was described for the systems. This protein activity coefficient data was related to a protein's solubility behavior and this process and the results will be presented.

  3. Recycling of osmotic solutions in microwave-osmotic dehydration: product quality and potential for creation of a novel product.

    Science.gov (United States)

    Wray, Derek; Ramaswamy, Hosahalli S

    2016-08-01

    Despite osmotic dehydration being a cost effective process for moisture removal, the cost implications of making, regenerating, and properly disposing of the spent osmotic solutions contributes greatly to the economic feasibility of the drying operation. The potential for recycling of osmotic solutions and their use for creation of a novel product was explored using microwave-osmotic dehydration under continuous flow spray (MWODS) conditions. Identical runs were repeated 10 times to determine the progressive physical and compositional effects of the thermal treatment and leaching from the cranberry samples. The microbiological stability and constant drying performance indicated that MWODS would be well suited for employing recycled solutions. While the anthocyanin content of the solution never approached that of cranberry juice concentrate, it is demonstrated that the spent syrup can infuse these health positive components into another product (apple). This study found that re-using osmotic solutions is a viable option to reduce cost in future MWODS applications, with no detriment to product quality and potential to use the spent solution for novel products. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  4. Pathogenic waterborne free-living amoebae: An update from selected Southeast Asian countries.

    Science.gov (United States)

    Abdul Majid, Mohamad Azlan; Mahboob, Tooba; Mong, Brandon G J; Jaturas, Narong; Richard, Reena Leeba; Tian-Chye, Tan; Phimphila, Anusorn; Mahaphonh, Panomphanh; Aye, Kyaw Nyein; Aung, Wai Lynn; Chuah, Joon; Ziegler, Alan D; Yasiri, Atipat; Sawangjaroen, Nongyao; Lim, Yvonne A L; Nissapatorn, Veeranoot

    2017-01-01

    Data on the distribution of free-living amoebae is still lacking especially in Southeast Asian region. The aquatic environment revealed a high occurrence of free-living amoebae (FLA) due to its suitable condition and availability of food source, which subsequently causes infection to humans. A total of 94 water samples consisted of both treated and untreated from Laos (31), Myanmar (42), and Singapore (21) were investigated for the presence of pathogenic FLA. Each water sample was filtered and cultured onto non-nutrient agar seeded with live suspension of Escherichia coli and incubated at room temperature. Morphological identification was conducted for both trophozoites and cysts via microscopic stains (Giemsa and immunofluorescence). The presence of Naegleria-like structures was the most frequently encountered in both treated and untreated water samples, followed by Acanthamoeba-like and Vermamoeba-like features. To identify the pathogenic isolates, species-specific primer sets were applied for molecular identification of Acanthamoeba, Naegleria, and Vermamoeba. The pathogenic species of Acanthamoeba lenticulata and A. triangularis were detected from untreated water samples, while Vermamoeba vermiformis was found in both treated and untreated water samples. Our results suggested that poor water quality as well as inadequate maintenance and treatment might be the cause of this alarming problem since chlorine disinfection is ineffective in eradicating these amoebas in treated water samples. Regular monitoring and examination of water qualities are necessary in order to control the growth, hence, further preventing the widespread of FLA infections among the public.

  5. Enhanced survival but not amplification of Francisella spp. in the presence of free-living amoebae.

    Science.gov (United States)

    Buse, Helen Y; Schaefer, Frank W; Rice, Eugene W

    2017-03-01

    Transmission of Francisella tularensis, the etiologic agent of tularemia, has been associated with various water sources. Survival of many waterborne pathogens within free-living amoeba (FLA) is well documented; however, the role of amoebae in the environmental persistence of F. tularensis is unclear. In this study, axenic FLA cultures of Acanthamoeba castellanii, Acanthamoeba polyphaga, and Vermamoeba vermiformis were each inoculated with virulent strains of F. tularensis (Types A and B), the attenuated live vaccine strain, and Francisella novicida. Experimental parameters included low and high multiplicity of infection and incubation temperatures of 25 and 30 °C for 0-10 days. Francisella spp. survival was enhanced by the presence of FLA; however, bacterial growth and protozoa infectivity were not observed. In contrast, co-infections of A. polyphaga and Legionella pneumophila, used as an amoeba pathogen control, resulted in bacterial proliferation, cytopathic effects, and amoebal lysis. Collectively, even though short-term incubation with FLA was beneficial, the long-term effects on Francisella survival are unknown, especially given the expenditure of available amoebal derived nutrients and the fastidious nature of Francisella spp. These factors have clear implications for the role of FLA in Francisella environmental persistence.

  6. Exploring Virulence Determinants of Filamentous Fungal Pathogens through Interactions with Soil Amoebae.

    Science.gov (United States)

    Novohradská, Silvia; Ferling, Iuliia; Hillmann, Falk

    2017-01-01

    Infections with filamentous fungi are common to all animals, but attention is rising especially due to the increasing incidence and high mortality rates observed in immunocompromised human individuals. Here, Aspergillus fumigatus and other members of its genus are the leading causative agents. Attributes like their saprophytic life-style in various ecological niches coupled with nutritional flexibility and a broad host range have fostered the hypothesis that environmental predators could have been the actual target for some of their virulence determinants. In this mini review, we have merged the recent findings focused on the potential dual-use of fungal defense strategies against innate immune cells and soil amoebae as natural phagocytes. Well-established virulence attributes like the melanized surface of fungal conidia or their capacity to produce toxic secondary metabolites have also been found to be protective against the model amoeba Dictyostelium discoideum . Some of the recent advances during interaction studies with human cells have further promoted the adaptation of other amoeba infection models, including the wide-spread generalist Acanthamoeba castellanii , or less prominent representatives like Vermamoeba vermiformis . We further highlight prospects and limits of these natural phagocyte models with regard to the infection biology of filamentous fungi and in comparison to the phagocytes of the innate immune system.

  7. Bacteriolytic activities of the free-living soil amoebae, Acanthamoeba castellanii, Acanthamoeba polyphaga and Hartmannella vermiformis.

    Science.gov (United States)

    Weekers, P H; Engelberts, A M; Vogels, G D

    1995-10-01

    Bacteriolytic activities of axenically grown free-living soil amoebae Acanthamoeba castellanii, Acanthamoeba polyphaga and Hartmannella vermiformis towards various Gram-positive and Gram-negative bacteria were determined. A spectrophotometric assay revealed that the specific bacteriolytic activities of both Acanthamoeba species were higher as those of the three Hartmannella strains. Bacillus megaterium, Bacillus subtilis, Chromatium vinosum, Micrococcus luteus and Pseudomonas fluorescens were more easily lysed than the other bacteria tested. Agrobacterium tumefaciens, Klebsiella aerogenes and Serratia marcescens were hardly affected at all by the amoebal bacteriolytic activities. Among the Gram-negative bacteria we observed differences in lysis sensitivity while the Gram-positive bacteria tested were sensitive to lysis. Isoelectric focusing (IEF) gel-electrophoresis in the pH range 3-10 was performed to separate the bacteriolytic isoenzymes of amoebae. Bacteriolytic patterns were shown by using an activity assay in which lysis bands were formed in the agar/bacteria gel-overlay. The activity assay revealed remarkable differences in typical banding patterns for bacteriolytic activities among amoebae. Distinct differences between typical pI points of bacteriolytic activities in Acanthamoeba and Hartmannella were shown. Bacteriolytic activities of Hartmannella were more pronounced and observed in the isoelectric points (pI) range of 4.0-9.3 while for Acanthamoeba the range was pI 4.5-8.9.

  8. Elimination of free-living amoebae in fresh water with pulsed electric fields.

    Science.gov (United States)

    Vernhes, M C; Benichou, A; Pernin, P; Cabanes, P A; Teissié, J

    2002-08-01

    This study investigates the effects of pulsed electric fields on the inactivation of trophozoite form of Naegleria lovaniensis Ar9M-1 in batch and flow processes, systematically examining the lethal effect of field strength, pulse duration, number of pulses, and pulse frequency. Our results show that amoebae eradication is modulated by pulse parameters, composition of the pulsing medium, and physiological state of the cells. Cell survival is not related to the energy delivered to the cell suspension during the electrical treatment. For a given energy a strong field applied for a short cumulative pulse duration affects viability more than a weak field with a long cumulative pulsation. We also determine the optimal electrical conditions to obtain an inactivation rate higher than 95% while using the least energy. Flow processes allow to treat large-scale volumes. Our results show that the most efficient flow process for amoeba eradication requires a field parallel to the flow. Pulsed electric fields are a new and attractive method for inactivating amoebae in large volumes of fresh water.

  9. [Isolation of Legionella and free-living amoebae at hot spring spas in Kanagawa, Japan].

    Science.gov (United States)

    Kuroki, T; Yagita, K; Yabuuchi, E; Agata, K; Ishima, T; Katsube, Y; Endo, T

    1998-10-01

    Microbiological contamination of hot spring bath water is a public health concern. A province-wide survey was carried out to determine the extent and distribution of both Legionella and free-living amoebae contamination. Among 30 samples of hot spring bath from 12 sites in Kanagawa, Japan, L. pneumophila was detected in 21 water samples from 11 sites, ranging from 10(1)-10(3) CFU/100 ml. Serogroups 3, 5 and 6 of L. pneumophila were predominantly isolated from the samples. Naegleria (46.7%), Platyamoeba (33.3%), Acanthamoeba (10.0%) and 2 other genera of free-living amoebae were detected in 22 samples from 11 sites. One or more genera of host amoebae of Legionella occurred in 17 samples (56.7%) from 9 sites. Another thing to be noted is that 13 water samples contained N. lovaniensis. Although N. lovaniensis is nonpathogenic, it is considered an indicator organism for places that are suitable for the growth of N. fowleri, a causative agent of primary amoebic meningoencephalitis in man.

  10. Isolation of free-living amoebae from sarein hot springs in ardebil province, iran.

    Science.gov (United States)

    Badirzadeh, A; Niyyati, M; Babaei, Z; Amini, H; Badirzadeh, H; Rezaeian, M

    2011-06-01

    Free-living amoebae (FLA) are a group of ubiquitous protozoan, which are distributed in the natural and artificial environment sources. The main aim of the current study was to identify the presence of FLA in the recreational hot springs of Sarein in Ardebil Province of Iran. Seven recreational hot springs were selected in Sarein City and 28 water samples (four from each hot spring) were collected using 500 ml sterile plastic bottles during three month. Filtration of water samples was performed, and culture was done in non-nutrient agar medium enriched with Escherichia coli. Identification of the FLA was based on morphological criteria of cysts and trophozoites. Genotype identification of Acanthamoeba positive samples were also performed using sequencing based method. Overall, 12 out of 28 (42.9%) samples were positive for FLA which Acanthamoeba and Vahlkampfiid amoebae were found in one (3.6%) and 11 (39.3%) samples, respectively. Sequence analysis of the single isolate of Acanthamoeba revealed potentially pathogenic T(4) genotype corresponding to A. castellanii. Contamination of hot springs to FLA, such as Acanthamoeba T(4) genotype (A. castellanii) and Vahlkampfiid amoebae, could present a sanitary risk for high risk people, and health authorities must be aware of FLA presence.

  11. Calcium and initial surface binding phase of pinocytosis in Amoeba proteus

    Energy Technology Data Exchange (ETDEWEB)

    Prusch, R.D.

    1986-08-01

    The uptake of membrane-bound solute and external medium by bulk-phase pinocytosis in Amoeba proteus is influenced by the level of Ca/sup 2 +/ in the external medium. Increasing external Ca/sup 2 +/ to approx.10/sup -4/ M increases pinocytotic intensity, while increases in Ca/sup 2 +/ above this level decrease the intensity of pinocytosis. The initial interaction of pinocytotic inducers and Ca/sup +2/ at the surface of A moeba proteus was therefore examined. Alcain blue and Na/sup +/, both inducers of pinocytosis, differ in the manner with which they associate with the amoeba surface, suggesting the possibility of different pinocytosis-inducing sites on the amoeba surface. Low levels of external Ca/sup 2 +/ in the range of 3 x 10/sup -5/ to 4.5 x 10/sup -4/ M increase the amount of cationic inducer associated with the cell surface while, at the same time, decreasing anion association with the cell surface. It is suggested that Ca/sup 2 +/ influences ion association with the cell surface by controlling the availability of negative surface sites, which in turn influences pinocytotic intensity. Surface binding of Na/sup +/, Ca/sup 2 +/ and Cl/sup -/ was determined by adding /sup 22/Na, /sup 45/Ca or /sup 36/Cl.

  12. Genome-wide identification of pathogenicity factors of the free-living amoeba Naegleria fowleri.

    Science.gov (United States)

    Zysset-Burri, Denise C; Müller, Norbert; Beuret, Christian; Heller, Manfred; Schürch, Nadia; Gottstein, Bruno; Wittwer, Matthias

    2014-06-19

    The free-living amoeba Naegleria fowleri is the causative agent of the rapidly progressing and typically fatal primary amoebic meningoencephalitis (PAM) in humans. Despite the devastating nature of this disease, which results in > 97% mortality, knowledge of the pathogenic mechanisms of the amoeba is incomplete. This work presents a comparative proteomic approach based on an experimental model in which the pathogenic potential of N. fowleri trophozoites is influenced by the compositions of different media. As a scaffold for proteomic analysis, we sequenced the genome and transcriptome of N. fowleri. Since the sequence similarity of the recently published genome of Naegleria gruberi was far lower than the close taxonomic relationship of these species would suggest, a de novo sequencing approach was chosen. After excluding cell regulatory mechanisms originating from different media compositions, we identified 22 proteins with a potential role in the pathogenesis of PAM. Functional annotation of these proteins revealed, that the membrane is the major location where the amoeba exerts its pathogenic potential, possibly involving actin-dependent processes such as intracellular trafficking via vesicles. This study describes for the first time the 30 Mb-genome and the transcriptome sequence of N. fowleri and provides the basis for the further definition of effective intervention strategies against the rare but highly fatal form of amoebic meningoencephalitis.

  13. Exploring Virulence Determinants of Filamentous Fungal Pathogens through Interactions with Soil Amoebae

    Directory of Open Access Journals (Sweden)

    Silvia Novohradská

    2017-12-01

    Full Text Available Infections with filamentous fungi are common to all animals, but attention is rising especially due to the increasing incidence and high mortality rates observed in immunocompromised human individuals. Here, Aspergillus fumigatus and other members of its genus are the leading causative agents. Attributes like their saprophytic life-style in various ecological niches coupled with nutritional flexibility and a broad host range have fostered the hypothesis that environmental predators could have been the actual target for some of their virulence determinants. In this mini review, we have merged the recent findings focused on the potential dual-use of fungal defense strategies against innate immune cells and soil amoebae as natural phagocytes. Well-established virulence attributes like the melanized surface of fungal conidia or their capacity to produce toxic secondary metabolites have also been found to be protective against the model amoeba Dictyostelium discoideum. Some of the recent advances during interaction studies with human cells have further promoted the adaptation of other amoeba infection models, including the wide-spread generalist Acanthamoeba castellanii, or less prominent representatives like Vermamoeba vermiformis. We further highlight prospects and limits of these natural phagocyte models with regard to the infection biology of filamentous fungi and in comparison to the phagocytes of the innate immune system.

  14. Isolation of Free-Living Amoebae from Sarein Hot Springs in Ardebil Province, Iran

    Directory of Open Access Journals (Sweden)

    A Badirzadeh

    2011-06-01

    Full Text Available Background: Free-living amoebae (FLA are a group of ubiquitous protozoan, which are distrib­uted in the natural and artificial environment sources. The main aim of the current study was to identify the presence of FLA in the recreational hot springs of Sarein in Ardebil Province of Iran.Methods: Seven recreational hot springs were selected in Sarein City and 28 water samples (four from each hot spring were collected using 500 ml sterile plastic bottles during three month. Filtra­tion of water samples was performed, and culture was done in non-nutrient agar medium enriched with Escherichia coli. Identification of the FLA was based on morphological criteria of cysts and trophozoites. Genotype identification of Acanthamoeba positive samples were also per­formed using sequencing based method.Results: Overall, 12 out of 28 (42.9% samples were positive for FLA which Acanthamoeba and Vahlkampfiid amoebae were found in one (3.6% and 11 (39.3% samples, respectively. Se­quence analysis of the single isolate of Acanthamoeba revealed potentially pathogenic T4 geno­type corresponding to A. castellanii.Conclusion: Contamination of hot springs to FLA, such as Acanthamoeba T4 genotype (A. castel­lanii and Vahlkampfiid amoebae, could present a sanitary risk for high risk people, and health authorities must be aware of FLA presence.

  15. New genes involved in osmotic stress tolerance in Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Ramon Gonzalez

    2016-09-01

    Full Text Available Adaptation to changes in osmolarity is fundamental for the survival of living cells, and has implications in food and industrial biotechnology. It has been extensively studied in the yeast Saccharomyces cerevisiae, where the Hog1 stress activated protein kinase was discovered about 20 years ago. Hog1 is the core of the intracellular signaling pathway that governs the adaptive response to osmotic stress in this species. The main endpoint of this program is synthesis and intracellular retention of glycerol, as a compatible osmolyte. Despite many details of the signaling pathways and yeast responses to osmotic challenges have already been described, genome-wide approaches are contributing to refine our knowledge of yeast adaptation to hypertonic media. In this work, we used a quantitative fitness analysis approach in order to deepen our understanding of the interplay between yeast cells and the osmotic environment. Genetic requirements for proper growth under osmotic stress showed both common and specific features when hypertonic conditions were induced by either glucose or sorbitol. Tolerance to high-glucose content requires mitochondrial function, while defective protein targeting to peroxisome, GID-complex function (involved in negative regulation of gluconeogenesis, or chromatin dynamics, result in poor survival to sorbitol-induced osmotic stress. On the other side, the competitive disadvantage of yeast strains defective in the endomembrane system is relieved by hypertonic conditions. This finding points to the Golgi-endosome system as one of the main cell components negatively affected by hyperosmolarity. Most of the biological processes highlighted in this analysis had not been previously related to osmotic stress but are probably relevant in an ecological and evolutionary context.

  16. New Genes Involved in Osmotic Stress Tolerance in Saccharomyces cerevisiae

    Science.gov (United States)

    Gonzalez, Ramon; Morales, Pilar; Tronchoni, Jordi; Cordero-Bueso, Gustavo; Vaudano, Enrico; Quirós, Manuel; Novo, Maite; Torres-Pérez, Rafael; Valero, Eva

    2016-01-01

    Adaptation to changes in osmolarity is fundamental for the survival of living cells, and has implications in food and industrial biotechnology. It has been extensively studied in the yeast Saccharomyces cerevisiae, where the Hog1 stress activated protein kinase was discovered about 20 years ago. Hog1 is the core of the intracellular signaling pathway that governs the adaptive response to osmotic stress in this species. The main endpoint of this program is synthesis and intracellular retention of glycerol, as a compatible osmolyte. Despite many details of the signaling pathways and yeast responses to osmotic challenges have already been described, genome-wide approaches are contributing to refine our knowledge of yeast adaptation to hypertonic media. In this work, we used a quantitative fitness analysis approach in order to deepen our understanding of the interplay between yeast cells and the osmotic environment. Genetic requirements for proper growth under osmotic stress showed both common and specific features when hypertonic conditions were induced by either glucose or sorbitol. Tolerance to high-glucose content requires mitochondrial function, while defective protein targeting to peroxisome, GID-complex function (involved in negative regulation of gluconeogenesis), or chromatin dynamics, result in poor survival to sorbitol-induced osmotic stress. On the other side, the competitive disadvantage of yeast strains defective in the endomembrane system is relieved by hypertonic conditions. This finding points to the Golgi-endosome system as one of the main cell components negatively affected by hyperosmolarity. Most of the biological processes highlighted in this analysis had not been previously related to osmotic stress but are probably relevant in an ecological and evolutionary context. PMID:27733850

  17. Metabolic Response of Maize Roots to Hyperosmotic Shock 1

    Science.gov (United States)

    Spickett, Corinne M.; Smirnoff, Nicholas; Ratcliffe, R. George

    1992-01-01

    31P nuclear magnetic resonance spectroscopy was used to study the response of maize (Zea mays L.) root tips to hyperosmotic shock. The aim was to identify changes in metabolism that might be relevant to the perception of low soil water potential and the subsequent adaptation of the tissue to these conditions. Osmotic shock was found to result in two different types of response: changes in metabolite levels and changes in intracellular pH. The most notable metabolic changes, which were produced by all the osmotica tested, were increases in phosphocholine and vacuolar phosphate, with a transient increase in cytoplasmic phosphate. It was observed that treatment with ionic and nonionic osmotica produced different effects on the concentrations of bioenergetically important metabolites. It is postulated that these changes are the result of hydrolysis of phosphatidylcholine and other membrane phospholipids, due to differential activation of specific membrane-associated phospholipases by changes in the surface tension of the plasmalemma. These events may be important in the detection of osmotic shock and subsequent acclimatization. A cytoplasmic alkalinization was also observed during hyperosmotic treatment, and this response, which is consistent with the activation of the plasmalemma H+-ATPase, together with the other metabolic changes, may suggest the existence of a complex and integrated mechanism of osmoregulation. PMID:16669012

  18. Osmotic pressure of the cutaneous surface fluid of Rana esculenta

    DEFF Research Database (Denmark)

    Hviid Larsen, Erik; Ramløv, Hans

    2012-01-01

    The osmotic pressure of the cutaneous surface fluid (CSF) in vivo was measured for investigating whether evaporative water loss (EWL) derives from water diffusing through the skin or fluid secreted by exocrine subepidermal mucous glands. EWL was stimulated by subjecting R. esculenta to 30–34 °C....../Kg, n = 16. Osmolality of lymph was, 239 ± 4 mosmol/Kg, n = 8. Thus the flow of water across the epidermis would be in the direction from CSF to the interstitial fluid driven by the above osmotic gradients and/or coupled to the inward active Na+ flux via the slightly hyperosmotic paracellular...

  19. Melting under shock compression

    International Nuclear Information System (INIS)

    Bennett, B.I.

    1980-10-01

    A simple model, using experimentally measured shock and particle velocities, is applied to the Lindemann melting formula to predict the density, temperature, and pressure at which a material will melt when shocked from room temperature and zero pressure initial conditions

  20. Toxic Shock Syndrome

    Science.gov (United States)

    ... may also be caused by toxins produced by group A streptococcus (strep) bacteria. Toxic shock syndrome has been associated ... syndrome. The syndrome can also be caused by group A streptococcus (strep) bacteria. Risk factors Toxic shock syndrome can ...

  1. The potential influence of short-term environmental variability on the composition of testate amoeba communities in Sphagnum peatlands.

    Science.gov (United States)

    Sullivan, Maura E; Booth, Robert K

    2011-07-01

    Testate amoebae are a group of moisture-sensitive, shell-producing protozoa that have been widely used as indicators of changes in mean water-table depth within oligotrophic peatlands. However, short-term environmental variability (i.e., sub-annual) also probably influences community composition. The objective of this study was to assess the potential influence of short-term environmental variability on the composition of testate amoeba communities in Sphagnum-dominated peatlands. Testate amoebae and environmental conditions, including hourly measurements of relative humidity within the upper centimeter of the peatland surface, were examined throughout the 2008 growing season at 72 microsites within 11 peatlands of Pennsylvania and Wisconsin, USA. Relationships among testate amoeba communities, vegetation, depth to water table, pH, and an index of short-term environmental variability (EVI), were examined using nonmetric multidimensional scaling and correlation analysis. Results suggest that EVI influences testate amoeba communities, with some taxa more abundant under highly variable conditions (e.g., Arcella discoides, Difflugia pulex, and Hyalosphenia subflava) and others more abundant when environmental conditions at the peatland surface were relatively stable (e.g., Archerella flavum and Bullinularia indica). The magnitude of environmental variability experienced at the peatland surface appears to be primarily controlled by vegetation composition and density. In particular, sites with dense Sphagnum cover had lower EVI values than sites with loose-growing Sphagnum or vegetation dominated by vascular plants and/or non-Sphagnum bryophytes. Our results suggest that more environmental information may be inferred from testate amoebae than previously recognized. Knowledge of relationships between testate amoebae and short-term environmental variability should lead to more detailed and refined environmental inferences.

  2. Biomass shock pretreatment

    Science.gov (United States)

    Holtzapple, Mark T.; Madison, Maxine Jones; Ramirez, Rocio Sierra; Deimund, Mark A.; Falls, Matthew; Dunkelman, John J.

    2014-07-01

    Methods and apparatus for treating biomass that may include introducing a biomass to a chamber; exposing the biomass in the chamber to a shock event to produce a shocked biomass; and transferring the shocked biomass from the chamber. In some aspects, the method may include pretreating the biomass with a chemical before introducing the biomass to the chamber and/or after transferring shocked biomass from the chamber.

  3. Effect of road transport stress on Erthrocyte Osmotic Fragility (EOF ...

    African Journals Online (AJOL)

    After an overnight fast, venous blood was collected from each subject for the determination of serum cortisol, glucose concentration and erythrocyte osmotic fragility. The subjects were then transported at a speed of 65 – 75Km/h covering a distance of 180km. Thereafter venous blood was again collected (within 10 minutes) ...

  4. Mechanisms of drought resistance in grain legumes I: Osmotic ...

    African Journals Online (AJOL)

    Higher yield of chickpea and common bean under drought was augumented by turgor maintenance. The highest degree of turgor ... The major osmotica in chickpea were of organic origin, namely sugars and sugar alcohols contributing more than 50%, and amino compounds 20% of the osmotic pool. Calcium was the only ...

  5. The patterns of Osmotic Fragility and Thrombocytopenia in Nigerian ...

    African Journals Online (AJOL)

    Thrombocytopenia in severe malaria was significantly higher than that in uncomplicated malaria (X2 = 6.4 – 13.7; P < 0.05). At day 3 to 4 of treatment with quinine, parasitaemia became zero in all the malaria subjects but resolution of thrombocytopenia and osmotic fragility (except in uncomplicated malaria) to normalcy was ...

  6. The phenomenon of cross tolerance in osmotically and ionically ...

    African Journals Online (AJOL)

    In the present study, cell lines of local rice (Oryza sativa L.) cv. Swat-1 were incrementally adapted to osmotic [20% Poly ethylene glycol (PEG)] and ion specific (20 mM LiCl) stresses to investigate the phenomenon of cross tolerance. The tolerances of adapted lines were stable up to six generation on stress free medium.

  7. Self-consistent unstirred layers in osmotically driven flows

    DEFF Research Database (Denmark)

    Jensen, Kåre Hartvig; Bohr, Tomas; Bruus, Henrik

    2010-01-01

    on both sides of the membrane remain well mixed due to an external stirring mechanism. We investigate the effects of concentration boundary layers on the efficiency of osmotic pumping processes in the absence of external stirring, i.e. when all advection is provided by the osmosis itself. This case...

  8. Improved Erythrocyte Osmotic Fragility and Packed Cell Volume ...

    African Journals Online (AJOL)

    Aloe barbadensis is a popular house plant that has a long history of a multipurpose folk remedy. It has been documented to have anti-diabetic, antiseptic and anti-inflammatory effects. The effect of Aloe barbadensis juice extract on erythrocyte osmotic fragility, packed cell volume and haemoglobin concentration in Wistar rats ...

  9. Density-Gradient Determination of Osmotic Potential in Plant Cells

    Science.gov (United States)

    Nabors, Murray W.

    1973-01-01

    Describes a method for measuring osmotic potential which is suitable for high school and college biology classes. This method introduces students to the hard-to-visualize technique of using density gradients to separate cells or cell constituents of differing densities. (JR)

  10. Development of an electro-osmotic heat pump

    NARCIS (Netherlands)

    Stoel, J.P. van der; Oostendorp, P.A.

    1999-01-01

    The majority of heat pumps and refrigerators is driven by a mechanical compressor. Although they usually function very well, the search for new and in some cases better heat pumping concepts continues. One of the topics in this field is the development of an electro-osmotic heat pump. As each

  11. Erythrocyte osmotic fragility of pigs administered ascorbic acid and ...

    African Journals Online (AJOL)

    The experiment was carried out with the aim of investigating the effect of an antioxidant ascorbic acid on erythrocyte osmotic fragility of pigs transported by road for 4 h during the harmattan season. 16 pigs administered with ascorbic acid at the dose of 250 mg/kg per os and individually served as experimental animals and ...

  12. Osmotic Fragility in Stored Non-Detergent Washed Human ...

    African Journals Online (AJOL)

    Osmotic fragility (OF) of non-detergent washed erythrocytes was evaluated in Nigerian human male erythrocytes stored for 0h, 12h, 24h and 48h. Storage of these human erythrocytes for up to 24h did not significantly alter their membrane characteristics. Mean corpuscular fragility (MCF) diminished and correlated negatively ...

  13. Process modelling and optimization of osmotic dehydration assisted ...

    African Journals Online (AJOL)

    Osmotic dehydration (pretreatment) of red bell pepper in hypertonic salt (NaCl) solution and drying was studied. A 4X4X4 factorial experiment in a Randomized Complete Block Design (RCBD) was used for the pretreatment and pretreated samples were later dried in a fabricated laboratory dryer. Process variables ...

  14. Influence of osmotic and metal stresses on nitrogenase activity of ...

    African Journals Online (AJOL)

    SERVER

    2007-08-06

    Aug 6, 2007 ... Influence of osmotic and metal stresses on nitrogenase activity of cyanobacteria ısolated from paddy fields. Gulten OKMEN (Kurucuoglu)1*, Gonul DONMEZ2 and Sedat DONMEZ3. 1Muğla University, Faculty of Science and Arts, Department of Biology, Mugla, Turkıye. 2Ankara University, Faculty of Science ...

  15. Osmotic potential, photosynthetic abilities and growth characters of ...

    African Journals Online (AJOL)

    A positive correlation between physiological and growth parameters, including osmotic potential, photosynthetic pigments and water oxidation in photosystem II and Pn was demonstrated. These data provide the basis for the establishment of multivariate criteria for water deficit tolerance screening in oil palm breeding ...

  16. Alterations in the colonic microbiota in response to osmotic diarrhea.

    Science.gov (United States)

    Gorkiewicz, Gregor; Thallinger, Gerhard G; Trajanoski, Slave; Lackner, Stefan; Stocker, Gernot; Hinterleitner, Thomas; Gülly, Christian; Högenauer, Christoph

    2013-01-01

    Diseases of the human gastrointestinal (GI) tract are often accompanied by diarrhea with profound alterations in the GI microbiota termed dysbiosis. Whether dysbiosis is due to the disease itself or to the accompanying diarrhea remains elusive. With this study we characterized the net effects of osmotic diarrhea on the composition of the GI microbiota in the absence of disease. We induced osmotic diarrhea in four healthy adults by oral administration of polyethylene glycol 4000 (PEG). Stool as well as mucosa specimens were collected before, during and after diarrhea and 16S rDNA-based microbial community profiling was used to assess the microbial community structure. Stool and mucosal microbiotas were strikingly different, with Firmicutes dominating the mucosa and Bacteroidetes the stools. Osmotic diarrhea decreased phylotype richness and showed a strong tendency to equalize the otherwise individualized microbiotas on the mucosa. Moreover, diarrhea led to significant relative shifts in the phyla Bacteroidetes and Firmicutes and to a relative increase in the abundance of Proteobacteria on the mucosa, a phenomenon also noted in several inflammatory and diarrheal GI diseases. Changes in microbial community structure induced by osmotic diarrhea are profound and show similarities to changes observed in other GI diseases including IBD. These effects so must be considered when specimens from diarrheal diseases (i.e. obtained by stratification of samples according to diarrheal status) or conditions wherein bowel preparations like PEG (i.e. specimens obtained during endoscopy) are used.

  17. Alterations in the colonic microbiota in response to osmotic diarrhea.

    Directory of Open Access Journals (Sweden)

    Gregor Gorkiewicz

    Full Text Available BACKGROUND & AIMS: Diseases of the human gastrointestinal (GI tract are often accompanied by diarrhea with profound alterations in the GI microbiota termed dysbiosis. Whether dysbiosis is due to the disease itself or to the accompanying diarrhea remains elusive. With this study we characterized the net effects of osmotic diarrhea on the composition of the GI microbiota in the absence of disease. METHODS: We induced osmotic diarrhea in four healthy adults by oral administration of polyethylene glycol 4000 (PEG. Stool as well as mucosa specimens were collected before, during and after diarrhea and 16S rDNA-based microbial community profiling was used to assess the microbial community structure. RESULTS: Stool and mucosal microbiotas were strikingly different, with Firmicutes dominating the mucosa and Bacteroidetes the stools. Osmotic diarrhea decreased phylotype richness and showed a strong tendency to equalize the otherwise individualized microbiotas on the mucosa. Moreover, diarrhea led to significant relative shifts in the phyla Bacteroidetes and Firmicutes and to a relative increase in the abundance of Proteobacteria on the mucosa, a phenomenon also noted in several inflammatory and diarrheal GI diseases. CONCLUSIONS: Changes in microbial community structure induced by osmotic diarrhea are profound and show similarities to changes observed in other GI diseases including IBD. These effects so must be considered when specimens from diarrheal diseases (i.e. obtained by stratification of samples according to diarrheal status or conditions wherein bowel preparations like PEG (i.e. specimens obtained during endoscopy are used.

  18. Osmotic dehydration - a pre-treatment for pineapple drying

    CSIR Research Space (South Africa)

    Lombard, GE

    2006-02-01

    Full Text Available Cayenne- type pineapple pieces. The effects of osmotic dehydration on mass transfer properties such as water loss, solids gain and weight reduction were investigated. The results obtained were also analysed in terms of WL/SG ratio since this parameter can...

  19. Root water extraction under combined water and osmotic stress

    NARCIS (Netherlands)

    Jong van Lier, de Q.; Dam, van J.C.; Metselaar, K.

    2009-01-01

    Using a numerical implicit model for root water extraction by a single root in a symmetric radial flow problem, based on the Richards equation and the combined convection-dispersion equation, we investigated some aspects of the response of root water uptake to combined water and osmotic stress. The

  20. Osmotic pressure of ring polymer solutions : A Monte Carlo study

    NARCIS (Netherlands)

    Flikkema, Edwin; Brinke, Gerrit ten

    2000-01-01

    Using the wall theorem, the osmotic pressure of ring polymers in solution has been determined using an off-lattice topology conserving Monte Carlo algorithm. The ring polymers are modeled as freely-jointed chains with point-like beads, i.e., under conditions corresponding to θ-conditions for the

  1. Osmotic generation of 'anomalous' fluid pressures in geological environments

    Science.gov (United States)

    Neuzii, C.E.

    2000-01-01

    Osmotic pressures are generated by differences in chemical potential of a solution across a membrane. But whether osmosis can have a significant effect on the pressure of fluids in geological environments has been controversial, because the membrane properties of geological media are poorly understood. 'Anomalous' pressures - large departures from hydrostatic pressure that are not explicable in terms of topographic or fluid-density effects are widely found in geological settings, and are commonly considered to result from processes that alter the pore or fluid volume, which in turn implies crustal changes happening at a rate too slow to observe directly. Yet if osmosis can explain some anomalies, there is no need to invoke such dynamic geological processes in those cases. Here I report results of a nine- year in situ measurement of fluid pressures and solute concentrations in shale that are consistent with the generation of large (up to 20 MPa) osmotic-pressure anomalies which could persist for tens of millions of years. Osmotic pressures of this magnitude and duration can explain many of the pressure anomalies observed in geological settings. The require, however, small shale porosity and large contrasts in the amount of dissolved solids in the pore waters - criteria that may help to distinguish between osmotic and crystal-dynamic origins of anomalous pressures.

  2. An analysis of electro-osmotic and magnetohydrodynamic heat pipes

    International Nuclear Information System (INIS)

    Harrison, M.A.

    1988-01-01

    Mechanically simple methods of improving heat transport in heat pipes are investigated. These methods are electro-osmotic and magnetohydrodynamic augmentation. For the electro-osmotic case, a detailed electrokinetic model is used. The electrokinetic model used includes the effects of pore surface curvature and multiple ion diffusivities. The electrokinetic model is extended to approximate the effects of elevated temperature. When the electro-osmotic model is combined with a suitable heat-pipe model, it is found that the electro-osmotic pump should be a thin membrane. Arguments are provided that support the use of a volatile electrolyte. For the magnetohydrodynamic case, a brief investigation is provided. A quasi-one-dimensional hydromagnetic duct flow model is used. This hydromagnetic model is extended to approximate flow effects unique to heat pipes. When combined with a suitable heat pipe model, it is found that there is no performance gain for the case considered. In fact, there are serious pressure-distribution problems that have not been previously recognized. Potential solutions to these pressure-distribution problems are suggested

  3. Controlled porosity solubility modulated osmotic pump tablets of gliclazide.

    Science.gov (United States)

    Banerjee, Arti; Verma, P R P; Gore, Subhash

    2015-06-01

    A system that can deliver drug at a controlled rate is very important for the treatment of various chronic diseases such as diabetes, asthma, and heart disease. Poorly water-soluble drug with pH-dependent solubility such as gliclazide (GLZ) offers challenges in the controlled-release formulation because of low dissolution rate and poor bioavailability. Solid dispersion (SD) of GLZ consisted of hydroxypropyl cellulose (HPC-SSL) as a polymeric solubilizer was manufactured by hot melt extrusion (HME) technology. Then, controlled porosity osmotic pump (CPOP) tablet of gliclazide was designed to deliver drug in a controlled manner up to 16 h. The developed formulation was optimized for type and level of pore former and coating weight gain. The optimized formulation was found to exhibit zero order kinetics independent of pH and agitation speed but depends on osmotic pressure of dissolution media indicated that mechanism of drug release was osmotic pressure. The in vivo performance prediction of developed formulation using convolution approach revealed that the developed formulation was superior to the existing marketed extended-release formulation in terms of attaining steady state plasma levels and indicated adequate exposure in translating hypoglycemic response. The prototype solubilization method combined with controlled porosity osmotic pump based technique could provide a unique way to increase dissolution rate and bioavailability of many poorly water-soluble, narrow therapeutic index drugs used in diabetes, cardiovascular diseases, etc.

  4. Impact of osmotic stress on protein diffusion in Lactococcus lactis

    NARCIS (Netherlands)

    Mika, Jacek; Schavemaker, Paul; Krasnikov, Viktor; Poolman, Bert

    2014-01-01

    We measured translational diffusion of proteins in the cytoplasm and plasma membrane of the Gram-positive bacterium Lactococcus lactis and probed the effect of osmotic upshift. For cells in standard growth medium the diffusion coefficients for cytosolic proteins (27 and 582 kDa) and 12-transmembrane

  5. Molecular sieving properties of the cytoplasm of Escherichia coli and consequences of osmotic stress

    NARCIS (Netherlands)

    Mika, Jacek T.; van den Bogaart, Geert; Veenhoff, Liesbeth; Krasnikov, Victor; Poolman, Bert

    We determined the diffusion coefficients (D) of (macro)molecules of different sizes (from ~0.5 to 600 kDa) in the cytoplasm of live Escherichia coli cells under normal osmotic conditions and osmotic upshift. D values decreased with increasing molecular weight of the molecules. Upon osmotic upshift,

  6. Modeling osmotic salinity effects on yield characteristics of substrate-grown greenhouse crops

    NARCIS (Netherlands)

    Sonneveld, C.; Bos, van den A.L.; Voogt, W.

    2004-01-01

    In a series of experiments with different osmotic potentials in the root environment, various vegetables, and ornamentals were grown in a substrate system. The osmotic potential was varied by addition of nutrients. Yield characteristics of the crop were related to the osmotic potential of the

  7. A Simple Membrane Osmometer System & Experiments that Quantitatively Measure Osmotic Pressure

    Science.gov (United States)

    Marvel, Stephen C.; Kepler, Megan V.

    2009-01-01

    It is important for students to be exposed to the concept of osmotic pressure. Understanding this concept lays the foundation for deeper discussions that lead to more theoretical aspects of water movement associated with the concepts of free energy, water potential, osmotic potential, pressure potential, and osmotic adjustment. The concept of…

  8. Alleviation of osmotic stress of water and salt in germination and ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-07-04

    Jul 4, 2008 ... The osmotic potential of the control solution was -0.20 MPa. The osmotic potentials of the two osmotic agents. (PEG 6000 and NaCl) were read with a Wescor Vapour Pressure. Osmometer- 5520). Seed germination test and seedling growth. The treated and untreated seeds were then transferred to Petri.

  9. Cryopreservation of coffee zygotic embryos: dehydration and osmotic rehydration

    Directory of Open Access Journals (Sweden)

    Maísa de Siqueira Pinto

    Full Text Available ABSTRACT Conservation of plant genetic resources is important to prevent genetic erosion. Seed banks are the most common method of ex situ conservation; however, coffee seeds can not be stored by conventional methods. Cryopreservation is a viable alternative for long-term conservation of species that produce intermediate or recalcitrant seeds, as coffee. The aim of this work was to cryopreserve Coffea arabica L. cv Catuaí Vermelho IAC 144 zygotic embryos, and analyse the effects of dehydration prior cryopreservation and osmotic rehydration after thawing, in embryos germination and seedlings formation after cryopreservation. Prior to cryopreservation, different dehydration times (0, 15, 30, 60 and 120 min were tested. Dehydrated embryos were cryopreserved in liquid nitrogen for 1 hour, and after thawing were rehydrated by osmotic solutions. Dehydrated and non-cryopreserved embryos were also analysed. The test with 2,3,5 triphenyl tetrazolium chloride (TTC was used to evaluate the embryos viability. Non-dehydrated embryos did not survive after freezing. Embryos that were dehydrated until 20% of the moisture content did not germinate when osmotic rehydration was not performed. In contrast, cryopreserved embryos with the same moisture content presented 98% germination when they were rehydrated slowly in osmotic solution. According to tetrazolium tests, embryos presented maximum viability (75% after dehydration for 60 minutes (23% moisture content. Therefore, coffee zygotic embryos (Coffea arabica L. cv. Catuaí Vermelho can be successfully cryopreserved using physical dehydration in silica gel for 60 minutes (23% moisture content, followed by osmotic rehydration after thawing. This method allowed a germination of 98% of cryopreserved zygotic embryos.

  10. Genetic structure of a morphological species within the amoeba genus Korotnevella (Amoebozoa: Discosea), revealed by the analysis of two genes.

    Science.gov (United States)

    Zlatogursky, Vasily V; Kudryavtsev, Alexander; Udalov, Ilya A; Bondarenko, Natalya; Pawlowski, Jan; Smirnov, Alexey

    2016-10-01

    Amoebae of the genus Korotnevella are covered with scales, the structure of which is believed to be species-specific and allows distinguishing species reliably at the morphological level. We studied members of this genus in order to assess the genetic structure of the local populations of amoebae. For the present study we isolated nine freshwater strains of Korotnevella, belonging to three species, from two locations in North-Western Russia. In order to obtain data on the population structure of these amoebae, we identified all isolates based on the light-microscopic morphology and scale structure and investigated both inter-strain and intra-strain polymorphism of Cox I and 18S rRNA genes. Results show that both genes provide congruent patterns of population structure. The Cox I gene appears to be more reliable DNA barcode while the 18S rRNA gene shows an interesting pattern of polymorphism, which may represent phylotypes of amoebae. Local population of amoebae in every studied species consists of a number of genetic lineages (phylotypes), some shared between the populations while others are unique to a local habitat. Copyright © 2016. Published by Elsevier GmbH.

  11. Hunting for agile prey: trophic specialisation in leptophryid amoebae (Vampyrellida, Rhizaria) revealed by two novel predators of planktonic algae.

    Science.gov (United States)

    Hess, Sebastian

    2017-09-01

    Vampyrellid amoebae (Vampyrellida, Rhizaria) are widespread in freshwater, marine and terrestrial ecosystems and consume a wide range of eukaryotes, e.g. algae, fungi and micrometazoa. Environmental sequences indicate that only a small fraction of their genetic diversity is phenotypically characterised, emphasising the need to further explore unknown vampyrellids and their interactions with prey organisms. This study tests the prey range specificity of three vampyrellid amoebae with 49 strains of three common groups of freshwater algae (Zygnematophyceae, Euglenophyceae and Volvocales), and documents specific interactions by time-lapse microscopy. Two of the amoebae, here introduced as the novel genera Arachnomyxa and Planctomyxa based on morphology and SSU rRNA gene comparisons, display a complementary prey range and consume motile algae, namely Volvocales and Euglenophyceae, respectively. This reveals the existence of specialised 'plankton feeders' in the vampyrellid family Leptophryidae, contrasting with the strikingly broad prey range of Leptophrys vorax. The distinct autecological characteristics found in this group of morphologically rather indistinct amoebae contribute to our knowledge about the vastly understudied vampyrellid amoebae. Furthermore, time-lapse observations suggest that euglenoid movements exerted by the sluggish species of the 'Euglena deses group' as a reaction to vampyrellid contact may serve as an effective defence against microbial predators. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. Survival of Campylobacter jejuni in co-culture with Acanthamoeba castellanii: role of amoeba-mediated depletion of dissolved oxygen.

    Science.gov (United States)

    Bui, Xuan Thanh; Winding, Anne; Qvortrup, Klaus; Wolff, Anders; Bang, Dang Duong; Creuzenet, Carole

    2012-08-01

    Campylobacter jejuni is a major cause of infectious diarrhoea worldwide but relatively little is known about its ecology. In this study, we examined its interactions with Acanthamoeba castellanii, a protozoan suspected to serve as a reservoir for bacterial pathogens. We observed rapid degradation of intracellular C.jejuni in A.castellanii 5 h post gentamicin treatment at 25°C. Conversely, we found that A.castellanii promoted the extracellular growth of C.jejuni in co-cultures at 37°C in aerobic conditions. This growth-promoting effect did not require amoebae - bacteria contact. The growth rates observed with or without contact with amoeba were similar to those observed when C.jejuni was grown in microaerophilic conditions. Preconditioned media prepared with live or dead amoebae cultivated with or without C.jejuni did not promote the growth of C.jejuni in aerobic conditions. Interestingly, the dissolved oxygen levels of co-cultures with or without amoebae - bacteria contact were much lower than those observed with culture media or with C.jejuni alone incubated in aerobic conditions, and were comparable with levels obtained after 24 h of growth of C.jejuni under microaerophilic conditions. Our studies identified the depletion of dissolved oxygen by A.castellanii as the major contributor for the observed amoeba-mediated growth enhancement. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  13. Control of Branchionus sp. and Amoeba sp. in cultures of Arthrospira sp. Control de Branchionus sp. y Amoeba sp. en cultivos de Arthrospira sp.

    Directory of Open Access Journals (Sweden)

    Carlos Méndez

    2012-09-01

    Full Text Available Cultivation of cyanobacterium Arthrospira sp. has been developed in many countries for the production of proteins, pigments and other compounds. Outdoor mass cultures are often affected by biological contamination, drastically reducing productivity as far as bringing death. This study evaluates the control of Branchionus sp. and Amoeba sp. with two chemical compounds: urea (U and ammonium bicarbonate (AB, in laboratory conditions and outdoor mass culture of Arthrospira sp. The lethal concentration 100 (LC100 at 24 h for Branchionus sp. and Amoeba sp. determined was of 60-80 mg L-1 (U and 100-150 mg L-1 (AB. The average effective inhibition concentration for 50% of the population (IC50 in Arthrospira sp., after 72 h, was 80 mg L-1 (U and 150 mg L-1 (AB. The application of doses of 60 mg L-1 (U or 100 mg L-1 (AB in the outdoor mass culture of this contaminated microalga, completely inhibited grazing and did not affect the growth of Arthrospira sp. but rather promoted rapid recovery of algal density at levels prior to infestation. These compounds provided an economical and effective control of predators in cultures of Arthrospira sp.El cultivo de la cianobacteria Arthrospira sp. ha sido desarrollado en muchos países para la obtención de proteínas, pigmentos y otros compuestos. Cultivo que a nivel industrial se ve afectado frecuentemente por contaminación biológica, reduciendo drásticamente la productividad hasta causar la muerte. Este estudio evalúa el control de Branchionus sp. y de Amoeba sp. con dos compuestos químicos, la urea (U y bicarbonato de amonio (AB en cultivos de Arthrospira sp. La concentración letal 100 (LC100 determinada a las 24 h para Branchionus sp. y Amoeba sp. fue de 60-80 mg L-1 (U y 100-150 mg L-1 (AB. La concentración media de inhibición efectiva, después de 72 h, para el 50% de la población (IC50 en Arthrospira fue de 80 mg L-1 (U y 150 mg L-1 (AB. La aplicación de dosis de 60 mg L-1 (U ó 100 mg L-1 (AB en

  14. Investigating the role of free-living amoebae as a reservoir for Mycobacterium ulcerans.

    Science.gov (United States)

    Amissah, Nana Ama; Gryseels, Sophie; Tobias, Nicholas J; Ravadgar, Bahram; Suzuki, Mitsuko; Vandelannoote, Koen; Durnez, Lies; Leirs, Herwig; Stinear, Timothy P; Portaels, Françoise; Ablordey, Anthony; Eddyani, Miriam

    2014-09-01

    The reservoir and mode of transmission of Mycobacterium ulcerans, the causative agent of Buruli ulcer, still remain a mystery. It has been suggested that M. ulcerans persists with difficulty as a free-living organism due to its natural fragility and inability to withstand exposure to direct sunlight, and thus probably persists within a protective host environment. We investigated the role of free-living amoebae as a reservoir of M. ulcerans by screening the bacterium in free-living amoebae (FLA) cultures isolated from environmental specimens using real-time PCR. We also followed the survival of M. ulcerans expressing green fluorescence protein (GFP) in Acanthameoba castellanii by flow cytometry and observed the infected cells using confocal and transmission electron microscopy for four weeks in vitro. IS2404 was detected by quantitative PCR in 4.64% of FLA cultures isolated from water, biofilms, detritus and aerosols. While we could not isolate M. ulcerans, 23 other species of mycobacteria were cultivated from inside FLA and/or other phagocytic microorganisms. Laboratory experiments with GFP-expressing M. ulcerans in A. castellani trophozoites for 28 days indicated the bacteria did not replicate inside amoebae, but they could remain viable at low levels in cysts. Transmission electron microscopy of infected A. castellani confirmed the presence of bacteria within both trophozoite vacuoles and cysts. There was no correlation of BU notification rate with detection of the IS2404 in FLA (r = 0.07, n = 539, p = 0.127). This study shows that FLA in the environment are positive for the M. ulcerans insertion sequence IS2404. However, the detection frequency and signal strength of IS2404 positive amoabae was low and no link with the occurrence of BU was observed. We conclude that FLA may host M. ulcerans at low levels in the environment without being directly involved in the transmission to humans.

  15. Coexistence of free-living amoebae and bacteria in selected South African hospital water distribution systems.

    Science.gov (United States)

    Muchesa, P; Leifels, M; Jurzik, L; Hoorzook, K B; Barnard, T G; Bartie, C

    2017-01-01

    Pathogenic free-living amoebae (FLA), such as Naegleria fowleri, Balamuthia mandrillaris and Acanthamoeba species isolated from aquatic environments have been implicated in central nervous system, eye and skin human infections. They also allow the survival, growth and transmission of bacteria such as Legionella, Mycobacteria and Vibrio species in water systems. The purpose of this study was to investigate the co-occurrence of potentially pathogenic FLA and their associated bacteria in hospital water networks in Johannesburg, South Africa. A total of 178 water (n = 95) and swab (n = 83) samples were collected from two hospital water distribution systems. FLA were isolated using the amoebal enrichment technique and identified using PCR and 18S rDNA sequencing. Amoebae potentially containing intra-amoebal bacteria were lysed and cultured on blood agar plates. Bacterial isolates were characterized using the VITEK®2 compact System. Free-living amoebae were isolated from 77 (43.3 %) of the samples. Using microscopy, PCR and 18S rRNA sequencing, Acanthamoeba spp. (T3 and T20 genotypes), Vermamoeba vermiformis and Naegleria gruberi specie were identified. The Acanthamoeba T3 and T20 genotypes have been implicated in eye and central nervous system infections. The most commonly detected bacterial species were Serratia marcescens, Stenotrophomonas maltophilia, Delftia acidovorans, Sphingomonas paucimobilis and Comamonas testosteroni. These nosocomial pathogenic bacteria are associated with systematic blood, respiratory tract, the urinary tract, surgical wounds and soft tissues infections. The detection of FLA and their associated opportunistic bacteria in the hospital water systems point out to a potential health risk to immune-compromised individuals.

  16. The Opuntia streptacantha OpsHSP18 Gene Confers Salt and Osmotic Stress Tolerance in Arabidopsis thaliana

    Science.gov (United States)

    Salas-Muñoz, Silvia; Gómez-Anduro, Gracia; Delgado-Sánchez, Pablo; Rodríguez-Kessler, Margarita; Jiménez-Bremont, Juan Francisco

    2012-01-01

    Abiotic stress limits seed germination, plant growth, flowering and fruit quality, causing economic decrease. Small Heat Shock Proteins (sHSPs) are chaperons with roles in stress tolerance. Herein, we report the functional characterization of a cytosolic class CI sHSP (OpsHSP18) from Opuntia streptacantha during seed germination in Arabidopsis thaliana transgenic lines subjected to different stress and hormone treatments. The over-expression of the OpsHSP18 gene in A. thaliana increased the seed germination rate under salt (NaCl) and osmotic (glucose and mannitol) stress, and in ABA treatments, compared with WT. On the other hand, the over-expression of the OpsHSP18 gene enhanced tolerance to salt (150 mM NaCl) and osmotic (274 mM mannitol) stress in Arabidopsis seedlings treated during 14 and 21 days, respectively. These plants showed increased survival rates (52.00 and 73.33%, respectively) with respect to the WT (18.75 and 53.75%, respectively). Thus, our results show that OpsHSP18 gene might have an important role in abiotic stress tolerance, in particular in seed germination and survival rate of Arabidopsis plants under unfavorable conditions. PMID:22949853

  17. In vitro screening of potato genotypes for osmotic stress tolerance

    Directory of Open Access Journals (Sweden)

    Gelmesa Dandena

    2017-02-01

    Full Text Available Potato (Solanum tuberosum L. is a cool season crop which is susceptible to both drought and heat stresses. Lack of suitable varieties of the crop adapted to drought-prone areas of the lowland tropics deprives farmers living in such areas the opportunity to produce and use the crop as a source of food and income. As a step towards developing such varieties, the present research was conducted to evaluate different potato genotypes for osmotic stress tolerance under in vitro conditions and identify drought tolerant genotypes for future field evaluation. The experiment was carried out at the Leibniz University of Hannover, Germany, by inducing osmotic stress using sorbitol at two concentrations (0.1 and 0.2 M in the culture medium. A total of 43 genotypes collected from different sources (27 advanced clones from CIP, nine improved varieties, and seven farmers’ cultivars were used in a completely randomized design with four replications in two rounds. Data were collected on root and shoot growth. The results revealed that the main effects of genotype, sorbitol treatment, and their interactions significantly (P < 0.01 influenced root and shoot growthrelated traits. Under osmotic stress, all the measured root and shoot growth traits were significantly correlated. The dendrogram obtained from the unweighted pair group method with arithmetic mean allowed grouping of the genotypes into tolerant, moderately tolerant, and susceptible ones to a sorbitol concentration of 0.2 M in the culture medium. Five advanced clones (CIP304350.100, CIP304405.47, CIP392745.7, CIP388676.1, and CIP388615.22 produced shoots and rooted earlier than all other genotypes, with higher root numbers, root length, shoot and root mass under osmotic stress conditions induced by sorbitol. Some of these genotypes had been previously identified as drought-tolerant under field conditions, suggesting the capacity of the in vitro evaluation method to predict drought stress tolerant

  18. Computational identification of putative miRNAs and their target genes in pathogenic amoeba Naegleria fowleri.

    Science.gov (United States)

    Padmashree, Dyavegowda; Swamy, Narayanaswamy Ramachandra

    2015-01-01

    Naegleria fowleri is a parasitic unicellular free living eukaryotic amoeba. The parasite spreads through contaminated water and causes primary amoebic meningoencephalitis (PAM). Therefore, it is of interest to understand its molecular pathogenesis. Hence, we analyzed the parasite genome for miRNAs (microRNAs) that are non-coding, single stranded RNA molecules. We identified 245 miRNAs using computational methods in N. fowleri, of which five miRNAs are conserved. The predicted miRNA targets were analyzed by using miRanda (software) and further studied the functions by subsequently annotating using AmiGo (a gene ontology web tool).

  19. Confocal Laser Scanning Microscopy and Two Photon Excitation Microscopy as Tools to Study Testate Amoebae

    Czech Academy of Sciences Publication Activity Database

    Burdíková, Zuzana; Čapek, Martin; Ostašov, Pavel; Mitchell, E.A.D.; Machač, Jiří; Kubínová, Lucie

    2010-01-01

    Roč. 16, Suppl.2 (2010), s. 1142-1143 ISSN 1431-9276. [Microscopy and Microanalysis 2010. Portland, 01.08.2010-05.08.2010] R&D Projects: GA MŠk(CZ) LC06063; GA ČR(CZ) GA102/08/0691; GA ČR(CZ) GA304/09/0733 Institutional research plan: CEZ:AV0Z50110509; CEZ:AV0Z60050516 Keywords : testate amoeba e * confocal microscopy * two-photon microscopy Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.179, year: 2010

  20. Quantitative analysis of glycerol accumulation, glycolysis and growth under hyper osmotic stress.

    Directory of Open Access Journals (Sweden)

    Elzbieta Petelenz-Kurdziel

    Full Text Available We provide an integrated dynamic view on a eukaryotic osmolyte system, linking signaling with regulation of gene expression, metabolic control and growth. Adaptation to osmotic changes enables cells to adjust cellular activity and turgor pressure to an altered environment. The yeast Saccharomyces cerevisiae adapts to hyperosmotic stress by activating the HOG signaling cascade, which controls glycerol accumulation. The Hog1 kinase stimulates transcription of genes encoding enzymes required for glycerol production (Gpd1, Gpp2 and glycerol import (Stl1 and activates a regulatory enzyme in glycolysis (Pfk26/27. In addition, glycerol outflow is prevented by closure of the Fps1 glycerol facilitator. In order to better understand the contributions to glycerol accumulation of these different mechanisms and how redox and energy metabolism as well as biomass production are maintained under such conditions we collected an extensive dataset. Over a period of 180 min after hyperosmotic shock we monitored in wild type and different mutant cells the concentrations of key metabolites and proteins relevant for osmoadaptation. The dataset was used to parameterize an ODE model that reproduces the generated data very well. A detailed computational analysis using time-dependent response coefficients showed that Pfk26/27 contributes to rerouting glycolytic flux towards lower glycolysis. The transient growth arrest following hyperosmotic shock further adds to redirecting almost all glycolytic flux from biomass towards glycerol production. Osmoadaptation is robust to loss of individual adaptation pathways because of the existence and upregulation of alternative routes of glycerol accumulation. For instance, the Stl1 glycerol importer contributes to glycerol accumulation in a mutant with diminished glycerol production capacity. In addition, our observations suggest a role for trehalose accumulation in osmoadaptation and that Hog1 probably directly contributes to the

  1. Effects of Grazing by the Free-Living Soil Amoebae Acanthamoeba castellanii, Acanthamoeba polyphaga, and Hartmannella vermiformis on Various Bacteria

    Science.gov (United States)

    Weekers, Peter H. H.; Bodelier, Paul L. E.; Wijen, John P. H.; Vogels, Godfried D.

    1993-01-01

    Cultures of 10 different bacteria were used to serve as food sources for axenically grown Acanthamoeba castellanii, Acanthamoeba polyphaga, and Hartmannella vermiformis. The nonpigmented enterobacteriaceae Escherichia coli K-12 and Klebsiella aerogenes appeared to be excellent feed to all three amoebae. Hardly any growth or ammonium production was observed in tests with Chromatium vinosum and Serratia marcescens, which share the presence of pigmented compounds. Distinct differences in net ammonium production were detected and were correlated to the amoebal growth yield. In general, growth of amoebae and ammonium production increased in the order A. polyphaga, A. castellanii, and H. vermiformis. PMID:16349000

  2. Effects of Naphthalene on DNA and RNA quantity in Amoeba proteus by using confocal laser scanning microscope

    Directory of Open Access Journals (Sweden)

    Khwanmuni, J.

    2006-01-01

    Full Text Available Effects of Naphthalene which is a carcinogen on changes of DNA and RNA quantities were studied with acridine orange stained cells under a confocal laser scanning microscope. It was found that DNA and RNA in amoebae nucleus and cytoplasm, reared in 0 (control, 3 and 8.85 mg/l (24h-LD50 at 0 and 12 h. showed a statistically significant difference (p<0.05. The more naphthalene concentrations and larger incubation periods had greater effects on DNA and RNA decreases in amoebae nucleus and cytoplasm.

  3. SSU rRNA reveals a sequential increase in shell complexity among the euglyphid testate amoebae (Rhizaria: Euglyphida)

    DEFF Research Database (Denmark)

    Lara, Enrique; Heger, Thierry J; Mitchell, Edward A D

    2007-01-01

    The existing data on the molecular phylogeny of filose testate amoebae from order Euglyphida has revealed contradictions between traditional morphological classification and SSU rRNA phylogeny and, moreover, the position of several important genera remained unknown. We therefore carried out a study...... aiming to fill several important gaps and better understand the relationships among the main euglyphid testate amoebae and the evolutionary steps that led to the present diversity at a higher level. We obtained new SSU rRNA sequences from five genera and seven species. This new phylogeny obtained shows...

  4. Self-consistent unstirred layers in osmotically driven flows

    Science.gov (United States)

    Bruus, Henrik; Hartvig Jensen, Kåre; Bohr, Tomas

    2010-11-01

    It has long been recognized, that the osmotic transport characteristics of membranes may be strongly influenced by the presence of unstirred concentration boundary layers adjacent to the membrane. Previous experimental as well as theoretical works have mainly focused on the case where the solutions on both sides of the membrane remain well-mixed due to an external stirring mechanism. We investigate the effects of concentration boundary layers on the efficiency of osmotic pumping processes in the absence of external stirring i.e. when all advection is provided by the osmosis itself. This case is relevant in the study of intracellular flows, e.g. in plants. For such systems, we show that no well-defined boundary layer thickness exists and that the reduction in concentration can be estimated by a surprisingly simple mathematical relation across a wide range of geometries and P'eclet numbers. This work is accepted for publication in Journal of Fluid Mechanics.

  5. Response of midpiece vesicles on human sperm to osmotic stress

    DEFF Research Database (Denmark)

    Abraham-Peskir, Joanna V; Chantler, Eric; Uggerhøj, Erik

    2002-01-01

    BACKGROUND: We investigated the osmotic response of midpiece vesicles (MPV) on human sperm. METHODS: Light microscopy, transmission X-ray microscopy and computer-aided semen analysis was used to investigate sperm in normozoospermic semen from healthy donors, separated from semen and suspended...... in hyper- or hypo-osmotic solutions. RESULTS: The mean incidence of MPV-bearing sperm in semen was 31% (range 8-71; n = 47). MPV were morphologically different from cytoplasmic droplets. The incidence of MPV-bearing sperm in separated populations increased reversibly after washing in Sperm Preparation...... Medium but not after washing in seminal plasma. There was an inverse relationship between medium osmolality and both MPV-bearing sperm incidence and MPV diameter. However, initial osmolality in semen from different donors did not correlate with incidence of MPV-bearing sperm. Furthermore, a direct...

  6. Optimization of the Energy Output of Osmotic Power Plants

    Directory of Open Access Journals (Sweden)

    Florian Dinger

    2013-01-01

    Full Text Available On the way to a completely renewable energy supply, additional alternatives to hydroelectric, wind, and solar power have to be investigated. Osmotic power is such an alternative with a theoretical global annual potential of up to 14400 TWh (70% of the global electricity consumption of 2008 per year. It utilizes the phenomenon that upon the mixing of fresh water and oceanic salt water (e.g., at a river mouth, around 2.88 MJ of energy per 1 m3 of fresh water is released. Here, we describe a new approach to derive operational parameter settings for osmotic power plants using a pressure exchanger for optimal performance, either with respect to maximum generated power or maximum extracted energy. Up to now, only power optimization is discussed in the literature, but when considering the fresh water supply as a limiting factor, the energy optimization appears as the challenging task.

  7. Glucose Monitoring System Based on Osmotic Pressure Measurements

    Directory of Open Access Journals (Sweden)

    Alexandra LEAL

    2011-02-01

    Full Text Available This paper presents the design and development of a prototype sensor unit for implementation in a long-term glucose monitoring system suitable for estimating glucose levels in people suffering from diabetes mellitus. The system utilizes osmotic pressure as the sensing mechanism and consists of a sensor prototype that is integrated together with a pre-amplifier and data acquisition unit for both data recording and processing. The sensor prototype is based on an embedded silicon absolute pressure transducer and a semipermeable nanoporous membrane that is enclosed in the sensor housing. The glucose monitoring system facilitates the integration of a low power microcontroller that is combined with a wireless inductive powered communication link. Experimental verification have proven that the system is capable of tracking osmotic pressure changes using albumin as a model compound, and thereby show a proof of concept for novel long term tracking of blood glucose from remote sensor nodes.

  8. Analytical Expressions for Thermo-Osmotic Permeability of Clays

    Science.gov (United States)

    Gonçalvès, J.; Ji Yu, C.; Matray, J.-M.; Tremosa, J.

    2018-01-01

    In this study, a new formulation for the thermo-osmotic permeability of natural pore solutions containing monovalent and divalent cations is proposed. The mathematical formulation proposed here is based on the theoretical framework supporting thermo-osmosis which relies on water structure alteration in the pore space of surface-charged materials caused by solid-fluid electrochemical interactions. The ionic content balancing the surface charge of clay minerals causes a disruption in the hydrogen bond network when more structured water is present at the clay surface. Analytical expressions based on our heuristic model are proposed and compared to the available data for NaCl solutions. It is shown that the introduction of divalent cations reduces the thermo-osmotic permeability by one third compared to the monovalent case. The analytical expressions provided here can be used to advantage for safety calculations in deep underground nuclear waste repositories.

  9. Vasogenic shock physiology

    OpenAIRE

    Gkisioti, Sotiria; Mentzelopoulos, Spyros D

    2011-01-01

    Sotiria Gkisioti, Spyros D MentzelopoulosDepartment of Intensive Care Medicine, University of Athens Medical School, Evaggelismos General Hospital, Athens, GreeceAbstract: Shock means inadequate tissue perfusion by oxygen-carrying blood. In vasogenic shock, this circulatory failure results from vasodilation and/or vasoplegia. There is vascular hyporeactivity with reduced vascular smooth muscle contraction in response to α1 adrenergic agonists. Considering vasogenic shock, one can un...

  10. Life Shocks and Homelessness

    OpenAIRE

    Marah A. Curtis; Hope Corman; Kelly Noonan; Nancy Reichman

    2011-01-01

    We exploit an exogenous health shock--the birth of a child with a severe health condition--to investigate the causal effect of a life shock on homelessness. Using survey data from the Fragile Families and Child Wellbeing study that have been augmented with information from hospital medical records, we find that the health shock increases the likelihood of homelessness three years later, particularly in cities with high housing costs. Homelessness is defined using both a traditional measure an...

  11. Shock transformations in quartzite

    Science.gov (United States)

    Badjukov, D. D.; Koslov, E. A.; Zhugin, Yu. N.; Abakshin, E. V.

    1993-01-01

    We report results of studies of experimental shock metamorphism in a quartzite sample. Shock pressure increases in the experiment from a rim to a center of the bowl-shaped sample due to a design of a recovery assembly. The section along an equatorial plane shows a progressive development of shock metamorphism. On the basis of observations, it is proposed that diaplectic glass can be a product of quenching a melt.

  12. Interaction of MHD shocks

    International Nuclear Information System (INIS)

    Gundersen, R.M.

    1983-01-01

    A plane MHD shock wave of arbitrary strength meets a slender body moving at super-true-sonic speed in the opposite direction. The interaction between the given shock wave and the weak shock attached to the slender body is studied for aligned fields for axisymmetrical flow and for both aligned and transverse fields in the two-dimensional case. Formal solutions for the linearized flow in the interaction region are obtained by the use of integral transforms. (author)

  13. Cadmium affects osmotic phase and regulatory volume decrease in cultured human embryonic kidney cells

    Directory of Open Access Journals (Sweden)

    Rossana Morabito

    2016-06-01

    Full Text Available The present investigation aims to verify whether cadmium (Cd2+, a metal possibly accumulated in body tissues from air and food, affects cell volume regulation capability in cultured human embryonic kidney (HEK 293 Phoenix cells. The osmotic phase (OP, which is the expected cell swelling due to aquaporins involvement after hyposmotic challenge, and regulatory volume decrease (RVD, bringing cell volume back to control values through Ca2+-dependent ion efflux (K+ and Cl–, have been monitored in HEK 293 cells treated with Cd2+ (1-10-100 μM for different time intervals (30 min, 3 h, overnight and then submitted to 15 % hyposmotic shock. The results show that both 1 and 10 μM Cd2+ significantly reduced OP, whereas 100 μM impaired Cd2+ RVD mechanisms. The use of glutathione (GSH, 200 μM confirmed that Cd2+ elicited its effect via oxidative damage, being RVD inhibition after Cd2+ treatment prevented by this antioxidant compound. Our findings show that: i HEK 293 cells are a suitable model to assay the effect of xenobiotics on cell homeostasis; ii Cd2+, depending on its concentration, affects cell homeostasis at different levels, i.e. water and ion permeability, responsible for, respectively, OP and RVD mechanism, adding thus more information to the knowledge of Cd2+ toxicology.

  14. QseC Mediates Osmotic Stress Resistance and Biofilm Formation in Haemophilus parasuis

    Directory of Open Access Journals (Sweden)

    Lvqin He

    2018-02-01

    Full Text Available Haemophilus parasuis is known as a commensal organism discovered in the upper respiratory tract of swine where the pathogenic bacteria survive in various adverse environmental stress. QseC, a histidine protein kinase of the two-component regulatory systems CheY/QseC, is involved in the environmental adaptation in bacteria. To investigate the role of QseC in coping with the adverse environment stresses and survive in the host, we constructed a qseC mutant of H. parasuis serovar 13 strain (ΔqseC, MY1902. In this study, we found that QseC was involved in stress tolerance of H. parasuis, by the ΔqseC exhibited a decreased resistance to osmotic pressure, oxidative stress, and heat shock. Moreover, the ΔqseC weakened the ability to take up iron and biofilm formation. We also found that the QseC participate in sensing the epinephrine in environment to regulate the density of H. parasuis.

  15. Applied osmotic loading for promoting development of engineered cartilage

    OpenAIRE

    Sampat, Sonal R.; Dermksian, Matthew V.; Oungoulian, Sevan R.; Winchester, Robert J.; Bulinski, J. Chloë; Ateshian, Gerard A.; Hung, Clark T.

    2013-01-01

    This study investigated the potential use of static osmotic loading as a cartilage tissue engineering strategy for growing clinically relevant grafts from either synovium-derived stem cells (SDSCs) or chondrocytes. Bovine SDSCs and chondrocytes were individually encapsulated in 2% w/v agarose and divided into chondrogenic media of osmolarities 300 (hypotonic), 330 (isotonic), and 400 (hypertonic, physiologic) mOsM for up to 7 weeks. The application of hypertonic media to constructs comprised ...

  16. Rationalization of Sucrose Solution Using During the Fruit Osmotic Dehydration

    OpenAIRE

    Babić, Mirko; Babić, Ljiljana; Pavkov, Ivan; Radojčin, Milivoj

    2009-01-01

    The model of sustainable energy production of dried fruit conducted by using combined technology – the model that has been developed at the Faculty of Agriculture in Novi Sad – includes osmotic dehydration of fruit in sucrose solution. During the process of dehydration the moisture content of the solution is increased due to mass transfer of moisture from fruit. This article examines different models of recycling and concentrating of the solution. Thus, the model for concentrating of the solu...

  17. Impact of osmotic dehydration on the encapsulated apices survival ...

    African Journals Online (AJOL)

    L-1 activated charcoal) prior to encapsulation in alginate (3%) beads with calcium chloride (1.32M). Then, the apices were exposed to osmotic dehydration with two concentrations of sucrose (0.75M and 1.25M) at two durations (24h and 40h) before their culture in M2 medium (MS + 2mg.L-1 BAP, 100?g.L-1 d'ANA and 2g.

  18. Hydro-osmotic Instabilities in Active Membrane Tubes

    Science.gov (United States)

    Al-Izzi, Sami C.; Rowlands, George; Sens, Pierre; Turner, Matthew S.

    2018-03-01

    We study a membrane tube with unidirectional ion pumps driving an osmotic pressure difference. A pressure-driven peristaltic instability is identified, qualitatively distinct from similar tension-driven Rayleigh-type instabilities on membrane tubes. We discuss how this instability could be related to the function and biogenesis of membrane bound organelles, in particular, the contractile vacuole complex. The unusually long natural wavelength of this instability is in agreement with that observed in cells.

  19. Toxic Shock Syndrome (For Parents)

    Science.gov (United States)

    ... Safe Videos for Educators Search English Español Toxic Shock Syndrome KidsHealth / For Parents / Toxic Shock Syndrome What's ... en español Síndrome de shock tóxico About Toxic Shock Syndrome Toxic shock syndrome (TSS) is a serious ...

  20. Impact of osmotic stress on protein diffusion in Lactococcus lactis.

    Science.gov (United States)

    Mika, Jacek T; Schavemaker, Paul E; Krasnikov, Victor; Poolman, Bert

    2014-11-01

    We measured translational diffusion of proteins in the cytoplasm and plasma membrane of the Gram-positive bacterium Lactococcus lactis and probed the effect of osmotic upshift. For cells in standard growth medium the diffusion coefficients for cytosolic proteins (27 and 582 kDa) and 12-transmembrane helix membrane proteins are similar to those in Escherichia coli. The translational diffusion of GFP in L. lactis drops by two orders of magnitude when the medium osmolality is increased by ∼ 1.9 Osm, and the decrease in mobility is partly reversed in the presence of osmoprotectants. We find a large spread in diffusion coefficients over the full population of cells but a smaller spread if only sister cells are compared. While in general the diffusion coefficients we measure under normal osmotic conditions in L. lactis are similar to those reported in E. coli, the decrease in translational diffusion upon osmotic challenge in L. lactis is smaller than in E. coli. An even more striking difference is that in L. lactis the GFP diffusion coefficient drops much more rapidly with volume than in E. coli. We discuss these findings in the light of differences in turgor, cell volume, crowding and cytoplasmic structure of Gram-positive and Gram-negative bacteria. © 2014 John Wiley & Sons Ltd.

  1. Active osmotic exchanger for advanced filtration at the nano scale

    Science.gov (United States)

    Marbach, Sophie; Bocquet, Lyderic

    2015-11-01

    One of the main functions of the kidney is to remove the waste products of an organism, mostly by excreting concentrated urea while reabsorbing water and other molecules. The human kidney is capable of recycling about 200 liters of water per day, at the relatively low cost of 0.5 kJ/L (standard dialysis requiring at least 150 kJ/L). Kidneys are constituted of millions of parallel filtration networks called nephrons. The nephrons of all mammalian kidneys present a specific loop geometry, the Loop of Henle, that is believed to play a key role in the urinary concentrating mechanism. One limb of the loop is permeable to water and the other contains sodium pumps that exchange with a common interstitium. In this work, we take inspiration from this osmotic exchanger design to propose new nanofiltration principles. We first establish simple analytical results to derive general operating principles, based on coupled water permeable pores and osmotic pumps. The best filtration geometry, in terms of power required for a given water recycling ratio, is comparable in many ways to the mammalian nephron. It is not only more efficient than traditional reverse osmosis systems, but can also work at much smaller pressures (of the order of the blood pressure, 0.13 bar, as compared to more than 30 bars for pressure-retarded osmosis systems). We anticipate that our proof of principle will be a starting point for the development of new filtration systems relying on the active osmotic exchanger principle.

  2. Does Osmotic Stress Affect Natural Product Expression in Fungi?

    Science.gov (United States)

    Overy, David; Correa, Hebelin; Roullier, Catherine; Chi, Wei-Chiung; Pang, Ka-Lai; Rateb, Mostafa; Ebel, Rainer; Shang, Zhuo; Capon, Rob; Bills, Gerald; Kerr, Russell

    2017-08-13

    The discovery of new natural products from fungi isolated from the marine environment has increased dramatically over the last few decades, leading to the identification of over 1000 new metabolites. However, most of the reported marine-derived species appear to be terrestrial in origin yet at the same time, facultatively halo- or osmotolerant. An unanswered question regarding the apparent chemical productivity of marine-derived fungi is whether the common practice of fermenting strains in seawater contributes to enhanced secondary metabolism? To answer this question, a terrestrial isolate of Aspergillus aculeatus was fermented in osmotic and saline stress conditions in parallel across multiple sites. The ex-type strain of A. aculeatus was obtained from three different culture collections. Site-to-site variations in metabolite expression were observed, suggesting that subculturing of the same strain and subtle variations in experimental protocols can have pronounced effects upon metabolite expression. Replicated experiments at individual sites indicated that secondary metabolite production was divergent between osmotic and saline treatments. Titers of some metabolites increased or decreased in response to increasing osmolite (salt or glycerol) concentrations. Furthermore, in some cases, the expression of some secondary metabolites in relation to osmotic and saline stress was attributed to specific sources of the ex-type strains.

  3. Osmotic heat engine using thermally responsive ionic liquids

    KAUST Repository

    Zhong, Yujiang

    2017-07-11

    The osmotic heat engine (OHE) is a promising technology for converting low grade heat to electricity. Most of the existing studies have focused on thermolytic salt systems. Herein, for the first time, we proposed to use thermally responsive ionic liquids (TRIL) that have either an upper critical solution temperature (UCST) or lower critical solution temperature (LCST) type of phase behavior as novel thermolytic osmotic agents. Closed-loop TRIL-OHEs were designed based on these unique phase behaviors to convert low grade heat to work or electricity. Experimental studies using two UCST-type TRILs, protonated betaine bis(trifluoromethyl sulfonyl)imide ([Hbet][Tf2N]) and choline bis(trifluoromethylsulfonyl)imide ([Choline][Tf2N]) showed that (1) the specific energy of the TRIL-OHE system could reach as high as 4.0 times that of the seawater and river water system, (2) the power density measured from a commercial FO membrane reached up to 2.3 W/m2, and (3) the overall energy efficiency reached up to 2.6% or 18% of the Carnot efficiency at no heat recovery and up to 10.5% or 71% of the Carnet efficiency at 70% heat recovery. All of these results clearly demonstrated the great potential of using TRILs as novel osmotic agents to design high efficient OHEs for recovery of low grade thermal energy to work or electricity.

  4. Osmotic stress response in the wine yeast Dekkera bruxellensis.

    Science.gov (United States)

    Galafassi, Silvia; Toscano, Marco; Vigentini, Ileana; Piškur, Jure; Compagno, Concetta

    2013-12-01

    Dekkera bruxellensis is mainly associated with lambic beer fermentation and wine production and may contribute in a positive or negative manner to the flavor development. This yeast is able to produce phenolic compounds, such as 4-ethylguaiacol and 4-ethylphenol which could spoil the wine, depending on their concentration. In this work we have investigated how this yeast responds when exposed to conditions causing osmotic stress, as high sorbitol or salt concentrations. We observed that osmotic stress determined the production and accumulation of intracellular glycerol, and the expression of NADH-dependent glycerol-3-phosphate dehydrogenase (GPD) activity was elevated. The involvement of the HOG MAPK pathway in response to this stress condition was also investigated. We show that in D. bruxellensis Hog1 protein is activated by phosphorylation under hyperosmotic conditions, highlighting the conserved role of HOG MAP kinase signaling pathway in the osmotic stress response. Gene Accession numbers in GenBank: DbHOG1: JX65361, DbSTL1: JX965362. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Development and evaluation of microporous osmotic tablets of diltiazem hydrochloride

    Directory of Open Access Journals (Sweden)

    Afifa Bathool

    2012-01-01

    Full Text Available Microporous osmotic tablet of diltiazem hydrochloride was developed for colon targeting. These prepared microporous osmotic pump tablet did not require laser drilling to deliver the drug to the specific site of action. The tablets were prepared by wet granulation method. The prepared tablets were coated with microporous semipermeable membrane and enteric polymer using conventional pan coating process. The incorporation of sodium lauryl sulfate (SLS, a leachable pore-forming agent, could form in situ delivery pores while coming in contact with gastrointestinal medium. The effect of formulation variables was studied by changing the amounts of sodium alginate and NaCMC in the tablet core, osmogen, and that of pore-forming agent (SLS used in the semipermeable coating. As the amount of hydrophilic polymers increased, drug release rate prolonged. It was found that drug release was increased as the concentration of osmogen and pore-former was increased. Fourier transform infrared spectroscopy and Differential scanning calorimetry results showed that there was no interaction between drug and polymers. Scanning electron microscopic studies showed the formation of pores after predetermined time of coming in contact with dissolution medium. The formation of pores was dependent on the amount of pore former used in the semipermeable membrane. in vitro results showed acid-resistant, timed release at an almost zero order up to 24 hours. The developed osmotic tablets could be effectively used for prolonged delivery of Diltiazem HCl.

  6. Osmotic Heat Engine Using Thermally Responsive Ionic Liquids.

    Science.gov (United States)

    Zhong, Yujiang; Wang, Xinbo; Feng, Xiaoshuang; Telalovic, Selvedin; Gnanou, Yves; Huang, Kuo-Wei; Hu, Xiao; Lai, Zhiping

    2017-08-15

    The osmotic heat engine (OHE) is a promising technology for converting low grade heat to electricity. Most of the existing studies have focused on thermolytic salt systems. Herein, for the first time, we proposed to use thermally responsive ionic liquids (TRIL) that have either an upper critical solution temperature (UCST) or lower critical solution temperature (LCST) type of phase behavior as novel thermolytic osmotic agents. Closed-loop TRIL-OHEs were designed based on these unique phase behaviors to convert low grade heat to work or electricity. Experimental studies using two UCST-type TRILs, protonated betaine bis(trifluoromethyl sulfonyl)imide ([Hbet][Tf 2 N]) and choline bis(trifluoromethylsulfonyl)imide ([choline][Tf 2 N]) showed that (1) the specific energy of the TRIL-OHE system could reach as high as 4.0 times that of the seawater and river water system, (2) the power density measured from a commercial FO membrane reached up to 2.3 W/m 2 , and (3) the overall energy efficiency reached up to 2.6% or 18% of the Carnot efficiency at no heat recovery and up to 10.5% or 71% of the Carnet efficiency at 70% heat recovery. All of these results clearly demonstrated the great potential of using TRILs as novel osmotic agents to design high efficient OHEs for recovery of low grade thermal energy to work or electricity.

  7. Intravesical electro-osmotic administration of mitomycin C.

    Science.gov (United States)

    Di Stasi, Savino M; Verri, Cristian; Celestino, Francesco; De Carlo, Francesco; Pagliarulo, Vincenzo

    2016-10-04

    Bladder cancer is very common and most cases are diagnosed as nonmuscle invasive disease, which is characterized by its propensity to recur and progress. Intravesical therapy is used to delay recurrence and progression, while cystectomy is reserved for patients who are refractory to transurethral resection and intravesical therapy. There is an increasing interest in methods to enhance the delivery of intravesical chemotherapeutic agents to improve efficacy. In vitro and in vivo studies demonstrated that electro-osmosis of mitomycin C (MMC) is more effective in delivering this drug into the urothelium, lamina propria, and superficial muscle layers of the bladder wall than is passive transport. Higher MMC tissue concentrations might have a clinical impact in the treatment of nonmuscle invasive bladder cancer (NMIBC). In randomized trials, intravesical electro-osmotic MMC was associated with superior response rate in high-risk NMIBC cancer, compared with passive diffusion MMC transport. New strategies such as intravesical Bacillus Calmette-Guerin (BCG) combined with electro-osmotic MMC as well as intravesical pre-operative electro-osmotic MMC provided promising results in terms of higher remission rates and longer remission times.Device-assisted intravesical chemotherapy may be a useful ancillary procedure in the treatment of NMIBC. Its evaluation must be planned with respect to the technical functioning of equipment and their use for a clear purpose to avoid the financial and human costs associated with incorrect therapies.

  8. Old lineages in a new ecosystem: diversification of arcellinid amoebae (Amoebozoa and peatland mosses.

    Directory of Open Access Journals (Sweden)

    Omar Fiz-Palacios

    Full Text Available Arcellinid testate amoebae (Amoebozoa form a group of free-living microbial eukaryotes with one of the oldest fossil records known, yet several aspects of their evolutionary history remain poorly understood. Arcellinids occur in a range of terrestrial, freshwater and even brackish habitats; however, many arcellinid morphospecies such as Hyalosphenia papilio are particularly abundant in Sphagnum-dominated peatlands, a relatively new ecosystem that appeared during the diversification of Sphagnum species in the Miocene (5-20 Myr ago. Here, we reconstruct divergence times in arcellinid testate amoebae after selecting several fossils for clock calibrations and then infer whether or not arcellinids followed a pattern of diversification that parallels the pattern described for Sphagnum. We found that the diversification of core arcellinids occurred during the Phanerozoic, which is congruent with most arcellinid fossils but not with the oldest known amoebozoan fossil (i.e. at ca. 662 or ca. 750 Myr. Overall, Sphagnum and the Hyalospheniidae exhibit different patterns of diversification. However, an extensive molecular phylogenetic analysis of distinct clades within H. papilio species complex demonstrated a correlation between the recent diversification of H. papilio, the recent diversification of Sphagnum mosses, and the establishment of peatlands.

  9. Isolation and molecular characterization of free-living amoebae from different water sources in Italy.

    Science.gov (United States)

    Montalbano Di Filippo, Margherita; Santoro, Maristella; Lovreglio, Piero; Monno, Rosa; Capolongo, Carmen; Calia, Carla; Fumarola, Luciana; D'Alfonso, Rossella; Berrilli, Federica; Di Cave, David

    2015-03-24

    Free-living amoebae (FLA) are protozoa ubiquitous in Nature, isolated from a variety of environments worldwide. In addition to their natural distribution, some species have been found to be pathogenic to humans. In the present study a survey was conducted in order to evaluate the presence and to characterize at molecular level the isolates of amoebic organisms collected from different water sources in Italy. A total of 160 water samples were analyzed by culture and microscopic examination. FLA were found in 46 (28.7%) of the investigated water samples. Groundwater, well waters, and ornamental fountain waters were the sources with higher prevalence rates (85.7%, 50.0%, and 45.9%, respectively). Identification of FLA species/genotypes, based on the 18S rDNA regions, allowed to identify 18 (39.1%) Acanthamoeba isolates (genotypes T4 and T15) and 21 (45.6%) Vermamoeba vermiformis isolates. Other FLA species, including Vahlkampfia sp. and Naegleria spp., previously reported in Italy, were not recovered. The occurrence of potentially pathogenic free-living amoebae in habitats related to human population, as reported in the present study, supports the relevance of FLA as a potential health threat to humans.

  10. Two distinct sensing pathways allow recognition of Klebsiella pneumoniae by Dictyostelium amoebae.

    Science.gov (United States)

    Lima, Wanessa C; Balestrino, Damien; Forestier, Christiane; Cosson, Pierre

    2014-03-01

    Recognition of bacteria by metazoans is mediated by receptors that recognize different types of microorganisms and elicit specific cellular responses. The soil amoebae Dictyostelium discoideum feeds upon a variable mixture of environmental bacteria, and it is expected to recognize and adapt to various food sources. To date, however, no bacteria-sensing mechanisms have been described. In this study, we isolated a Dictyostelium mutant (fspA KO) unable to grow in the presence of non-capsulated Klebsiella pneumoniae bacteria, but growing as efficiently as wild-type cells in the presence of other bacteria, such as Bacillus subtilis. fspA KO cells were also unable to respond to K. pneumoniae and more specifically to bacterially secreted folate in a chemokinetic assay, while they responded readily to B. subtilis. Remarkably, both WT and fspA KO cells were able to grow in the presence of capsulated LM21 K. pneumoniae, and responded to purified capsule, indicating that capsule recognition may represent an alternative, FspA-independent mechanism for K. pneumoniae sensing. When LM21 capsule synthesis genes were deleted, growth and chemokinetic response were lost for fspA KO cells, but not for WT cells. Altogether, these results indicate that Dictyostelium amoebae use specific recognition mechanisms to respond to different K. pneumoniae elements. © 2013 John Wiley & Sons Ltd.

  11. Evidence of parasexual activity in "asexual amoebae" Cochliopodium spp. (Amoebozoa): extensive cellular and nuclear fusion.

    Science.gov (United States)

    Tekle, Yonas I; Anderson, O Roger; Lecky, Ariel F

    2014-09-01

    The majority of microbial eukaryotes have long been considered asexual, though new evidence indicates sex, or sexual-like (parasexual) behaviors that deviate from the usual union of two gametes, among other variant aspects. Over a dozen amoebozoans are implicated to have sexual stages. However, the exact mechanism by which sex occurs in these lineages remains elusive. This is mainly due to the diverse quality and cryptic nature of their life cycle. In this study we present evidence of some previously unreported aspects of the life cycle of an amoeba, Cochliopodium, that undergoes unusual intraspecific interactions using light microscopy and immunocytochemistry. Similar to other amoebozoans, Cochliopodium, is considered asexual with no published reports of sex or parasexuality. We also investigated environmental conditions that govern the observed intraspecific interactions. Both light microscopic and immunocytochemistry evidence demonstrates Cochliopodium undergoes cellular fusion (plasmogamy) and nuclear fusion (karyogamy). Large plasmodia eventually undergo karyogamy and contain large fused, polyploid, nuclei. These are observed to fragment, subsequently, by karyotomy (nuclear fission) and cytoplasmic fission to yield uninucleated amoebae. This process could lead to a non-meiotic, parasexual exchange of chromosomes in Cochliopodium. These findings strongly suggest that Cochliopodium is involved in parasexual activity and should no longer be considered strictly asexual. Copyright © 2014 Elsevier GmbH. All rights reserved.

  12. Development of a nested PCR assay to detect the pathogenic free-living amoeba Naegleria fowleri.

    Science.gov (United States)

    Réveiller, Fabienne L; Cabanes, Pierre-André; Marciano-Cabral, Francine

    2002-05-01

    Naegleria fowleri is the causative agent of primary amoebic meningoencephalitis, a fatal disease of the central nervous system that is acquired while swimming or diving in freshwater. A cDNA clone designated Mp2C15 obtained from N. fowleri was used as a probe to distinguish N. fowleri from other free-living amoebae. The Mp2C15 probe hybridized to genomic DNA from pathogenic N. fowleri and antigenically related non-pathogenic N. lovaniensis. Mp2C15 was digested with the restriction enzyme XbaI, resulting in two fragments, Mp2C15.G and Mp2C15.P. Four species of Naegleria and four species of Acanthamoeba were examined for reactivity with Mp2C15.P. Mp2C15.P was specific for N. fowleri and was used in the development of a nested PCR assay which is capable of detecting as little as 5 pg of N. fowleri DNA or five intact N. fowleri amoebae. In summary, a rapid, sensitive, and specific assay for the detection of N. fowleri was developed.

  13. Archaeological occurrences and historical review of the human amoeba, Entamoeba histolytica, over the past 6000years.

    Science.gov (United States)

    Le Bailly, Matthieu; Maicher, Céline; Dufour, Benjamin

    2016-08-01

    Understanding parasite history and the evolution of host/parasite relationships is one of the most important aspects of paleoparasitology. Within the framework of this research topic, this paper focuses on the human pathogenic amoeba, Entamoeba histolytica. The compilation of all the available archaeological data concerning this parasite leads to a first glimpse of the history of this parasite of current medical importance. Paleoparasitological investigation into this parasite uses immunological techniques and shows that the modern strain of E. histolytica has been present in Western Europe since at least the Neolithic period (3700yearsBCE), and could have originated in the Old World. The appearance of the modern amoeba strain in the pre-Columbian Americas and the Middle East around the 12th century CE gives rise to hypotheses as to how human migrations (Atlantic or Pacific routes) contributed to the diffusion of this pathogen, resulting in its current distribution. This compilation proves that parasites are valuable proxies for studying past human and animal migrations, and should be given more consideration in the future. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Serologic prevalence of amoeba-associated microorganisms in intensive care unit pneumonia patients.

    Directory of Open Access Journals (Sweden)

    Sabri Bousbia

    Full Text Available BACKGROUND: Patients admitted to intensive care units are frequently exposed to pathogenic microorganisms present in their environment. Exposure to these microbes may lead to the development of hospital-acquired infections that complicate the illness and may be fatal. Amoeba-associated microorganisms (AAMs are frequently isolated from hospital water networks and are reported to be associated to cases of community and hospital-acquired pneumonia. METHODOLOGY/PRINCIPAL FINDINGS: We used a multiplexed immunofluorescence assay to test for the presence of antibodies against AAMs in sera of intensive care unit (ICU pneumonia patients and compared to patients at the admission to the ICU (controls. Our results show that some AAMs may be more frequently detected in patients who had hospital-acquired pneumonia than in controls, whereas other AAMs are ubiquitously detected. However, ICU patients seem to exhibit increasing immune response to AAMs when the ICU stay is prolonged. Moreover, concomitant antibodies responses against seven different microorganisms (5 Rhizobiales, Balneatrix alpica, and Mimivirus were observed in the serum of patients that had a prolonged ICU stay. CONCLUSIONS/SIGNIFICANCE: Our work partially confirms the results of previous studies, which show that ICU patients would be exposed to water amoeba-associated microorganisms, and provides information about the magnitude of AAM infection in ICU patients, especially patients that have a prolonged ICU stay. However, the incidence of this exposure on the development of pneumonia remains to assess.

  15. Elucidation of the Role of 3-Hydroxy Fatty Acids in Cryptococcus-amoeba Interactions

    Directory of Open Access Journals (Sweden)

    Olihile M. Sebolai

    2017-04-01

    Full Text Available We previously reported that 3-hydroxy fatty acids promoted the survival of cryptococcal cells when acted upon by amoebae. To expand on this, the current study sought to explain how these molecules may protect cells. Our data suggest that 3-hydroxy fatty acids may subvert the internalization of cryptococcal cells via suppression of the levels of a fetuin A-like amoebal protein, which may be important for enhancing phagocytosis. Additionally, we show that an acapsular strain (that is devoid of 3-hydroxy fatty acids was protected against the effects of hydrogen peroxide when exogenous 3-hydroxy fatty acids were present, but not in the absence of 3-hydroxy fatty acids. A similar response profile was noted when a strain with a capsule was challenged with hydrogen peroxide. We also show that cryptococcal cells that naturally produce 3-hydroxy fatty acids were more resistant to the effects of amoebapore (an amoeba-specific hydrolytic enzyme, compared to cells that do not produce these molecules. Taken together, our findings suggest that 3-hydroxy fatty acids possess an anti-phagocytic activity that may be expressed when cells interact with macrophages. This may allow the yeast cells to evade immuno-processing.

  16. Spontaneous occurrence of antibodies against pathogenic amoebae of the limax group in domestic animals.

    Science.gov (United States)

    Cerva, L

    1981-01-01

    Sera of 1 218 animals were examined using indirect haemagglutination reaction with antigens of Naegleria fowleri and Acanthamoeba culbertsoni. Rabbit sera (214 samples) gave negative reaction with both antigens. Bovine sera (593 samples) reacted positively in 1.5%, particularly with the antigen of A. culbertsoni. Out of the 411 pigs examined 12% were positive with one or both of the antigens. In one of the pig farms of a modern type the positivity with one or both of the antigens. In one of the pig farms of a modern type the positivity was as much as 32.2%. The titres of positive animal sera have never been higher than 1 : 320. The amoebae of the limax group do not seem to be involved in the pathogenesis of diseases of cattle and rabbits. A sporadic occurrence of peracute cases is possible. In case of a sudden death, animals with symptoms of encephalitis or pneumonia should be examined for the presence of amoebae. Hypersensitivity should be considered as a possible cause of pig diseases.

  17. Isolation and Molecular Characterization of Free-Living Amoebae from Different Water Sources in Italy

    Directory of Open Access Journals (Sweden)

    Margherita Montalbano Di Filippo

    2015-03-01

    Full Text Available Free-living amoebae (FLA are protozoa ubiquitous in Nature, isolated from a variety of environments worldwide. In addition to their natural distribution, some species have been found to be pathogenic to humans. In the present study a survey was conducted in order to evaluate the presence and to characterize at molecular level the isolates of amoebic organisms collected from different water sources in Italy. A total of 160 water samples were analyzed by culture and microscopic examination. FLA were found in 46 (28.7% of the investigated water samples. Groundwater, well waters, and ornamental fountain waters were the sources with higher prevalence rates (85.7%, 50.0%, and 45.9%, respectively. Identification of FLA species/genotypes, based on the 18S rDNA regions, allowed to identify 18 (39.1% Acanthamoeba isolates (genotypes T4 and T15 and 21 (45.6% Vermamoeba vermiformis isolates. Other FLA species, including Vahlkampfia sp. and Naegleria spp., previously reported in Italy, were not recovered. The occurrence of potentially pathogenic free-living amoebae in habitats related to human population, as reported in the present study, supports the relevance of FLA as a potential health threat to humans.

  18. Design of an osmotic pressure sensor for sensing an osmotically active substance

    International Nuclear Information System (INIS)

    Ch, Nagesh; Paily, Roy P

    2015-01-01

    A pressure sensor based on the osmosis principle has been designed and demonstrated successfully for the sensing of the concentration levels of an osmotically active substance. The device is fabricated using the bulk micro-machining technique on a silicon on insulator (SOI) substrate. The substrate has a square cavity on the bottom side to fill with the reference glucose solution and a silicon (Si) membrane on the top side for the actuation. Two sets of devices, having membrane thicknesses of 10 µm and 25 µm, but the same area of 3 mm ×3 mm, are fabricated. The cavity is filled with a glucose solution of 100 mg dL −1 and it is sealed with a semi-permeable membrane made up of cellulose acetate material. The glucose solution is employed to prove the functionality of the device and it is tested for different glucose concentration levels, ranging from 50 mg dL −1 to 450 mg dL −1 . The output voltage obtained for the corresponding glucose concentration levels ranges from −6.7 mV to 22.7 mV for the 10 µm device and from −1.7 mV to 4 mV for the 25 µm device. The device operation was simulated using the finite element method (FEM) and the finite volume method (FVM), and the simulation and experimental results match closely. A response time of 40 min is obtained in the case of the 10 µm device compared to one of 30 min for the 25 µm device. The response times obtained for these devices are found to be small compared to those in similar works based on the osmosis principle. This pressure sensor has the potential to provide controlled drug delivery if it can be integrated with other microfluidic devices. (paper)

  19. Recent experimental data may point to a greater role for osmotic pressures in the subsurface

    Science.gov (United States)

    Neuzil, C.E.; Provost, A.M.

    2009-01-01

    Uncertainty about the origin of anomalous fluid pressures in certain geologic settings has caused researchers to take a second look at osmosis, or flow driven by chemical potential differences, as a pressure-generating process in the subsurface. Interest in geological osmosis has also increased because of an in situ experiment by Neuzil (2000) suggesting that Pierre Shale could generate large osmotic pressures when highly compacted. In the last few years, additional laboratory and in situ experiments have greatly increased the number of data on osmotic properties of argillaceous formations, but they have not been systematically examined. In this paper we compile these data and explore their implications for osmotic pressure generation in subsurface systems. Rather than base our analysis on osmotic efficiencies, which depend strongly on concentration, we calculated values of a quantity we term osmotic specific surface area (Aso) that, in principle, is a property of the porous medium only. The Aso values are consistent with a surprisingly broad spectrum of osmotic behavior in argillaceous formations, and all the formations tested exhibited at least a modest ability to generate osmotic pressure. It appears possible that under appropriate conditions some formations can be highly effective osmotic membranes able to generate osmotic pressures exceeding 30 MPa (3 km of head) at porosities as high as ??0.1 and pressures exceeding 10 MPa at porosities as high as ??0.2. These findings are difficult to reconcile with the lack of compelling field evidence for osmotic pressures, and we propose three explanations for the disparity: (1) Our analysis is flawed and argillaceous formations are less effective osmotic membranes than it suggests; (2) the necessary subsurface conditions, significant salinity differences within intact argillaceous formations, are rare; or (3) osmotic pressures are unlikely to be detected and are not recognized when encountered. The last possibility, that

  20. Recent experimental data may point to a greater role for osmotic pressures in the subsurface

    Science.gov (United States)

    Neuzil, C.E.; Provost, A.M.

    2009-01-01

    Uncertainty about the origin of anomalous fluid pressures in certain geologic settings has caused researchers to take a second look at osmosis, or flow driven by chemical potential differences, as a pressure‐generating process in the subsurface. Interest in geological osmosis has also increased because of an in situ experiment by Neuzil (2000) suggesting that Pierre Shale could generate large osmotic pressures when highly compacted. In the last few years, additional laboratory and in situ experiments have greatly increased the number of data on osmotic properties of argillaceous formations, but they have not been systematically examined. In this paper we compile these data and explore their implications for osmotic pressure generation in subsurface systems. Rather than base our analysis on osmotic efficiencies, which depend strongly on concentration, we calculated values of a quantity we term osmotic specific surface area (Aso) that, in principle, is a property of the porous medium only. The Aso values are consistent with a surprisingly broad spectrum of osmotic behavior in argillaceous formations, and all the formations tested exhibited at least a modest ability to generate osmotic pressure. It appears possible that under appropriate conditions some formations can be highly effective osmotic membranes able to generate osmotic pressures exceeding 30 MPa (3 km of head) at porosities as high as ∼0.1 and pressures exceeding 10 MPa at porosities as high as ∼0.2. These findings are difficult to reconcile with the lack of compelling field evidence for osmotic pressures, and we propose three explanations for the disparity: (1) Our analysis is flawed and argillaceous formations are less effective osmotic membranes than it suggests; (2) the necessary subsurface conditions, significant salinity differences within intact argillaceous formations, are rare; or (3) osmotic pressures are unlikely to be detected and are not recognized when encountered. The last possibility

  1. SAXS investigations on lipid membranes under osmotic stress

    Energy Technology Data Exchange (ETDEWEB)

    Rubim, R.L.; Vieira, V.; Gerbelli, B.B.; Teixeira da Silva, E.R.; Oliveira, C.L.P.; Oliveira, E.A. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil)

    2012-07-01

    Full text: In this work we, experimentally, investigate the interactions between lipid bilayers. A structural characterization is performed by small angle x-ray scattering (SAXS) on multilamellar systems under known osmotic pressure. Changes in the composition of membranes can modify their mechanical properties and structural parameters, like the flexibility of these membranes, which plays a key role on the determination of the tridimensional organization of bilayers. The membranes are composed of soya lecithin, where the major component is DPPC (Dipalmitoylphosphatidylcholine), and fatty acids are incorporated to the membrane in different concentrations, in order to turn the membrane more fluid. The membranes are inserted in a solution of PVP [poly(vinyl-pyrrolidone) - 40000] and the polymer will apply an osmotic pressure on them. The osmotic pressure is controlled by preparing PVP solutions of desired composition and, as we know the concentration of polymer in solution, we can obtain the intensity of the osmotic pressure. SAXS experiments were done in order to determine the distance between the bilayer. From the position of the Bragg peaks, the lamellar periodicity (the thickness of the membranes plus their distance of separation) was determined. Using theoretical model for the form and structure factors we fitted those experimental data and determined the thickness of the membranes. The distance between the membranes was controlled by the osmotic pressure (P) applied to the membranes and, for a given pressure, we determine the distance between the bilayers (a) on equilibrium. The experimental curve P(a) is theoretically described by the different contributions from van der Waals, hydration and fluctuation forces. From the fitting of experimental curves, relevant parameters characterizing the strength of the different interactions are obtained, such as Hamaker and rigidity constant [2, 3]. We observe that the separation between the bilayers on equilibrium is

  2. Osmotic phenomena in application for hyperbaric oxygen treatment.

    Science.gov (United States)

    Babchin, A; Levich, E; Melamed M D, Y; Sivashinsky, G

    2011-03-01

    Hyperbaric oxygen (HBO) treatment defines the medical procedure when the patient inhales pure oxygen at elevated pressure conditions. Many diseases and all injuries are associated with a lack of oxygen in tissues, known as hypoxia. HBO provides an effective method for fast oxygen delivery in medical practice. The exact mechanism of the oxygen transport under HBO conditions is not fully identified. The objective of this article is to extend the colloid and surface science basis for the oxygen transport in HBO conditions beyond the molecular diffusion transport mechanism. At a pressure in the hyperbaric chamber of two atmospheres, the partial pressure of oxygen in the blood plasma increases 10 times. The sharp increase of oxygen concentration in the blood plasma creates a considerable concentration gradient between the oxygen dissolved in the plasma and in the tissue. The concentration gradient of oxygen as a non-electrolyte solute causes an osmotic flow of blood plasma with dissolved oxygen. In other words, the molecular diffusion transport of oxygen is supplemented by the convective diffusion raised due to the osmotic flow, accelerating the oxygen delivery from blood to tissue. A non steady state equation for non-electrolyte osmosis is solved asymptotically. The solution clearly demonstrates two modes of osmotic flow: normal osmosis, directed from lower to higher solute concentrations, and anomalous osmosis, directed from higher to lower solute concentrations. The fast delivery of oxygen from blood to tissue is explained on the basis of the strong molecular interaction between the oxygen and the tissue, causing an influx of oxygen into the tissue by convective diffusion in the anomalous osmosis process. The transport of the second gas, nitrogen, dissolved in the blood plasma, is also taken into the consideration. As the patient does not inhale nitrogen during HBO treatment, but exhales it along with oxygen and carbon dioxide, the concentration of nitrogen in blood

  3. Toxic Shock Syndrome (For Teens)

    Science.gov (United States)

    ... Safe Videos for Educators Search English Español Toxic Shock Syndrome KidsHealth / For Teens / Toxic Shock Syndrome What's ... it, then take some precautions. What Is Toxic Shock Syndrome? If you're a girl who's had ...

  4. Shock Probation in Iowa.

    Science.gov (United States)

    Boudouris, James; Turnbull, Bruce W.

    1985-01-01

    Compared characteristics and recidivism of 820 shock probationers with recidivism of parolees, straight probationers, and persons sentenced to residential facilities or halfway houses. The results indicated that age, prior juvenile or adult commitments, unemployment, and marital status were related to recidivism for all male shock probationers.…

  5. Our Favorite Film Shocks

    DEFF Research Database (Denmark)

    Willerslev, Rane; Suhr, Christian

    2014-01-01

    The modern medium of film has long been hailed for its capacity for producing shocks of an entertaining, thought-provoking, or even politically emancipative nature. But what is a shock, how and when does it occur, how long does it last, and are there particular techniques for producing cinematic...

  6. Climate shocks and conflict

    NARCIS (Netherlands)

    Papaioannou, Kostadis J.

    2016-01-01

    This paper offers a historical micro-level analysis of the impact of climate shocks on the incidence of civil conflict in colonial Nigeria (1912-1945). Primary historical sources on court cases, prisoners and homicides are used to capture conflict. To measure climate shocks we use the deviation

  7. Contrasting diversity of testate amoebae communities in Sphagnum and brown-moss dominated patches in relation to shell counts.

    Science.gov (United States)

    Lizoňová, Zuzana; Horsák, Michal

    2017-04-01

    Ecological studies of peatland testate amoebae are generally based on totals of 150 individuals per sample. However, the suitability of this standard has never been assessed for alkaline habitats such as spring fens. We explored the differences in testate amoeba diversity between Sphagnum and brown-moss microhabitats at a mire site with a highly diversified moss layer which reflects the small-scale heterogeneity in groundwater chemistry. Relationships between sampling efficiency and sample completeness were explored using individual-based species accumulation curves and the effort required to gain an extra species was assessed. Testate amoeba diversity differed substantially between microhabitats, with brown mosses hosting on average twice as many species and requiring greater shell totals to reach comparable sample analysis efficiency as for Sphagnum. Thus, for samples from alkaline conditions an increase in shell totals would be required and even an overall doubling up to 300 individuals might be considered for reliable community description. Our small-scale data are likely not robust enough to provide an ultimate solution for the optimization of shell totals. However, the results proved that testate amoebae communities from acidic and alkaline environments differ sharply in both species richness and composition and they might call for different methodological approaches. Copyright © 2017 Elsevier GmbH. All rights reserved.

  8. Shedding light on microbial dark matter: a TM6 bacterium as natural endosymbiont of a free-living amoeba.

    Science.gov (United States)

    Delafont, Vincent; Samba-Louaka, Ascel; Bouchon, Didier; Moulin, Laurent; Héchard, Yann

    2015-12-01

    The TM6 phylum belongs to the so-called microbial dark matter that gathers uncultivated bacteria detected only via DNA sequencing. Recently, the genome sequence of a TM6 bacterium (TM6SC1) has led to suggest that this bacterium would adopt an endosymbiotic life. In the present paper, free-living amoebae bearing a TM6 strain were isolated from a water network. The amoebae were identified as Vermamoeba vermiformis and the presence of a TM6 strain was detected by polymerase chain reaction and microscopy. The partial sequence of its 16S rRNA gene showed this strain to be closely related to the sequenced TM6SC1 strain. These bacteria displayed a pyriform shape and were found within V. vermiformis. Therefore, these bacteria were named Vermiphilus pyriformis. Interactions studies showed that V. pyriformis was highly infectious and that its relation with V. vermiformis was specific and highly stable. Finally, it was found that V. pyriformis inhibited the encystment of V. vermiformis. Overall, this study describes for the first time an endosymbiotic relationship between a TM6 bacterium and a free-living amoeba in the environment. It suggests that other bacteria of the TM6 phylum might also be endosymbiotic bacteria and may be found in other free-living amoebae or other organisms. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  9. A free-living amoeba with unusual pattern of mitochondrial structure isolated from Atlantic salmon, Salmo salar L

    Czech Academy of Sciences Publication Activity Database

    Dyková, Iva; Veverková, Marie; Fiala, Ivan; Macháčková, Blanka

    2002-01-01

    Roč. 41, - (2002), s. 415-419 ISSN 0065-1583 R&D Projects: GA AV ČR IAA6022202 Institutional research plan: CEZ:AV0Z6022909 Keywords : free-living amoeba * mitochondrial cristae * Salmo salar Subject RIV: EA - Cell Biology Impact factor: 0.446, year: 2002

  10. Quantitative detection of the free-living amoeba Hartmannella vermiformis in surface water by using real-time PCR

    NARCIS (Netherlands)

    Kuiper, M.W.; Valster, R.M.; Wullings, B.A.; Boonstra, H.; Smidt, H.; Kooij, van der D.

    2006-01-01

    A real-time PCR-based method targeting the 18S rRNA gene was developed for the quantitative detection of Hartmannella vermiformis, a free-living amoeba which is a potential host for Legionella pneumophila in warm water systems and cooling towers. The detection specificity was validated using genomic

  11. Effect of Common Drinking Water Disinfectants, Chlorine and Heat, on Free Legionella and Amoebae-Associated Legionella

    Science.gov (United States)

    Cervero-Aragó, Sílvia; Rodríguez-Martínez, Sarah; Puertas-Bennasar, Antoni; Araujo, Rosa M.

    2015-01-01

    Chlorine and thermal treatments are the most commonly used procedures to control and prevent Legionella proliferation in drinking water systems of large buildings. However, cases of legionellosis still occur in facilities with treated water. The purpose of this work was to model the effect of temperature and free chlorine applied in similar exposure conditions as in drinking water systems on five Legionella spp. strains and two amoebal strains of the genera Acanthamoeba. Inactivation models obtained were used to determine the effectiveness of the treatments applied which resulted more effective against Legionella than Acanthamoeba, especially those in cystic stages. Furthermore, to determine the influence of the relationship between L. pneumophila and Acanthamoeba spp. on the treatment effectiveness, inactivation models of the bacteria-associated amoeba were also constructed and compared to the models obtained for the free living bacteria state. The Legionella-amoeba association did not change the inactivation models, but it reduced the effectiveness of the treatments applied. Remarkably, at the lowest free chlorine concentration, 0.5 mg L-1, as well as at the lowest temperatures, 50°C and 55°C, the influence of the Legionella-amoeba associate state was the strongest in reducing the effectiveness of the treatments compared to the free Legionella state. Therefore, the association established between L. pneumophila and amoebae in the water systems indicate an increased health risk in proximal areas of the system (close to the tap) where lower free chlorine concentrations and lower temperatures are commonly observed. PMID:26241039

  12. Differential growth of Legionella pneumophila strains within a range of amoebae at various temperatures associated with in-premise plumbing

    Science.gov (United States)

    The potential effect of in-premise plumbing temperatures (24, 32, 37 and 41 °C) on the growth of five different L. pneumophila strains within free-living amoebae (Acanthamoeba polyphaga, Hartmannella vermiformis and Naegleria fowleri) was examined. Compared to controls only fed E...

  13. Reflection of curved shock waves

    Science.gov (United States)

    Mölder, S.

    2017-09-01

    Shock curvatures are related to pressure gradients, streamline curvatures and vorticity in flows with planar and axial symmetry. Explicit expressions, in an influence coefficient format, are used to relate post-shock pressure gradient, streamline curvature and vorticity to pre-shock gradients and shock curvature in steady flow. Using higher order, von Neumann-type, compatibility conditions, curved shock theory is applied to calculate the flow near singly and doubly curved shocks on curved surfaces, in regular shock reflection and in Mach reflection. Theoretical curved shock shapes are in good agreement with computational fluid dynamics calculations and experiment.

  14. Osmotic therapies added to antibiotics for acute bacterial meningitis

    Science.gov (United States)

    Wall, Emma Cb; Ajdukiewicz, Katherine Mb; Bergman, Hanna; Heyderman, Robert S; Garner, Paul

    2018-01-01

    Background Every day children and adults die from acute community-acquired bacterial meningitis, particularly in low-income countries, and survivors risk deafness, epilepsy and neurological disabilities. Osmotic therapies may attract extra-vascular fluid and reduce cerebral oedema, and thus reduce death and improve neurological outcomes. This is an update of a Cochrane Review first published in 2013. Objectives To evaluate the effects of osmotic therapies added to antibiotics for acute bacterial meningitis in children and adults on mortality, deafness and neurological disability. Search methods We searched CENTRAL (2017, Issue 1), MEDLINE (1950 to 17 February 2017), Embase (1974 to 17 February 2017), CINAHL (1981 to 17 February 2017), LILACS (1982 to 17 February 2017) and registers of ongoing clinical trials (ClinicalTrials.com, WHO ICTRP) (21 February 2017). We also searched conference abstracts and contacted researchers in the field (up to 12 December 2015). Selection criteria Randomised controlled trials testing any osmotic therapy in adults or children with acute bacterial meningitis. Data collection and analysis Two review authors independently screened the search results and selected trials for inclusion. Results are presented using risk ratios (RR) and 95% confidence intervals (CI) and grouped according to whether the participants received steroids or not. We used the GRADE approach to assess the certainty of the evidence. Main results We included five trials with 1451 participants. Four trials evaluated glycerol against placebo, and one evaluated glycerol against 50% dextrose; in addition three trials evaluated dexamethasone and one trial evaluated acetaminophen (paracetamol) in a factorial design. Stratified analysis shows no effect modification with steroids; we present aggregate effect estimates. Compared to placebo, glycerol probably has little or no effect on death in people with bacterial meningitis (RR 1.08, 95% CI 0.90 to 1.30; 5 studies, 1272

  15. Effect of UV irradiation (253.7 nm) on free Legionella and Legionella associated with its amoebae hosts.

    Science.gov (United States)

    Cervero-Aragó, Sílvia; Sommer, Regina; Araujo, Rosa M

    2014-12-15

    Water systems are the primary reservoir for Legionella spp., where the bacteria live in association with other microorganisms, such as free-living amoebae. A wide range of disinfection treatments have been studied to control and prevent Legionella colonization but few of them were performed considering its relation with protozoa. In this study, the effectiveness of UV irradiation (253.7 nm) using low-pressure lamps was investigated as a disinfection method for Legionella and amoebae under controlled laboratory conditions. UV treatments were applied to 5 strains of Legionella spp., 4 strains of free-living amoeba of the genera Acanthamoeba and Vermamoeba, treating separately trophozoites and cysts, and to two different co-cultures of Legionella pneumophila with the Acanthamoeba strains. No significant differences in the UV inactivation behavior were observed among Legionella strains tested which were 3 logs reduced for fluences around 45 J/m(2). UV irradiation was less effective against free-living amoebae; which in some cases required up to 990 J/m(2) to obtain the same population reduction. UV treatment was more effective against trophozoites compared to cysts; moreover, inactivation patterns were clearly different between the genus Acanthamoeba and Vermamoeba. For the first time data about Vermamoeba vermiformis UV inactivation has been reported in a study. Finally, the results showed that the association of L. pneumophila with free-living amoebae decreases the effectiveness of UV irradiation against the bacteria in a range of 1.5-2 fold. That fact demonstrates that the relations established between different microorganisms in the water systems can modify the effectiveness of the UV treatments applied. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Cheating does not explain selective differences at high and low relatedness in a social amoeba

    Directory of Open Access Journals (Sweden)

    Queller David C

    2010-03-01

    Full Text Available Abstract Background Altruism can be favored by high relatedness among interactants. We tested the effect of relatedness in experimental populations of the social amoeba Dictyostelium discoideum, where altruism occurs in a starvation-induced social stage when some amoebae die to form a stalk that lifts the fertile spores above the soil facilitating dispersal. The single cells that aggregate during the social stage can be genetically diverse, which can lead to conflict over spore and stalk allocation. We mixed eight genetically distinct wild isolates and maintained twelve replicated populations at a high and a low relatedness treatment. After one and ten social generations we assessed the strain composition of the populations. We expected that some strains would be out-competed in both treatments. In addition, we expected that low relatedness might allow the persistence of social cheaters as it provides opportunity to exploit other strains. Results We found that at high relatedness a single clone prevailed in all twelve populations. At low relatedness three clones predominated in all twelve populations. Interestingly, exploitation of some clones by others in the social stage did not explain the results. When we mixed each winner against the pool of five losers, the winner did not prevail in the spores because all contributed fairly to the stalk and spores. Furthermore, the dominant clone at high-relatedness was not cheated by the other two that persisted at low relatedness. A combination of high spore production and short unicellular stage most successfully explained the three successful clones at low relatedness, but not why one of them fared better at high relatedness. Differences in density did not account for the results, as the clones did not differ in vegetative growth rates nor did they change the growth rates over relevant densities. Conclusions These results suggest that social competition and something beyond solitary growth differences

  17. Advances in understanding of osmotic dehydration and vacuum impregnation of fruits

    OpenAIRE

    Tylewicz, Urszula

    2011-01-01

    Osmotic Dehydration and Vacuum Impregnation are interesting operations in the food industry with applications in minimal fruit processing and/or freezing, allowing to develop new products with specific innovative characteristics. Osmotic dehydration is widely used for the partial removal of water from cellular tissue by immersion in hypertonic (osmotic) solution. The driving force for the diffusion of water from the tissue is provided by the differences in water chemical potential between ...

  18. Effect of plasma colloid osmotic pressure on intraocular pressure during haemodialysis

    OpenAIRE

    Tokuyama, T.; Ikeda, T.; Sato, K.

    1998-01-01

    BACKGROUND—In a previous case report, it was shown that an increase in plasma colloid osmotic pressure induced by the removal of fluid during haemodialysis was instrumental in decreasing intraocular pressure. The relation between changes in intraocular pressure, plasma osmolarity, plasma colloid osmotic pressure, and body weight before and after haemodialysis is evaluated.
METHODS—Intraocular pressure, plasma osmolarity, plasma colloid osmotic pressure, and body weight were evaluated before a...

  19. Sarcolemmal blebs and osmotic fragility as correlates of irreversible ischemic injury in preconditioned isolated rabbit cardiomyocytes.

    Science.gov (United States)

    Armstrong, S C; Shivell, L C; Ganote, C E

    2001-01-01

    The hypothesis that irreversible ischemic injury is related to sub-sarcolemmal blebbing and an inherent osmotic fragility of the blebs was tested by subjecting isolated control and ischemically preconditioned (IPC) or calyculin A (CalA)-pretreated (protected) rabbit cardiomyocytes to ischemic pelleting followed by resuspension in 340, 170 or 85 mosmol medium containing trypan blue. At time points from 0-240 min, osmotic fragility was assessed by the percentage of trypan blue permeable cells. Membrane blebs were visualized with India ink preparations. Bleb formation, following acute hypo-osmotic swelling, developed by 75 min and increased with longer periods of ischemia. Osmotic fragility developed only after 75 min. Cells resuspended in 340 mosmol media did not form blebs and largely retained the ability to exclude trypan blue, even after 240 min ischemia. Although the latent tendency for osmotic blebbing preceded the development of osmotic fragility, most osmotically fragile cells became permeable without evident sarcolemmal bleb formation. The onset of osmotic fragility was delayed in protected cells, but protection did not reduce the bleb formation. It is concluded that blebbing and osmotic fragility are independent manifestations of ischemic injury. The principal locus of irreversible ischemic injury and the protection provided by IPC may lie within the sarcolemma rather than at sarcolemmal attachments to underlying adherens junctions.

  20. Transcriptome Profiling of Watermelon Root in Response to Short-Term Osmotic Stress.

    Science.gov (United States)

    Yang, Yongchao; Mo, Yanling; Yang, Xiaozheng; Zhang, Haifei; Wang, Yongqi; Li, Hao; Wei, Chunhua; Zhang, Xian

    2016-01-01

    Osmotic stress adversely affects the growth, fruit quality and yield of watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai). Increasing the tolerance of watermelon to osmotic stress caused by factors such as high salt and water deficit is an effective way to improve crop survival in osmotic stress environments. Roots are important organs in water absorption and are involved in the initial response to osmosis stress; however, few studies have examined the underlying mechanism of tolerance to osmotic stress in watermelon roots. For better understanding of this mechanism, the inbred watermelon accession M08, which exhibits relatively high tolerance to water deficits, was treated with 20% polyethylene glycol (PEG) 6000. The root samples were harvested at 6 h after PEG treatment and untreated samples were used as controls. Transcriptome analyses were carried out by Illumina RNA sequencing. A total of 5246 differentially expressed genes were identified. Gene ontology enrichment and biochemical pathway analyses of these 5246 genes showed that short-term osmotic stress affected osmotic adjustment, signal transduction, hormone responses, cell division, cell cycle and ribosome, and M08 may repress root growth to adapt osmotic stress. The results of this study describe the watermelon root transcriptome under osmotic stress and propose new insight into watermelon root responses to osmotic stress at the transcriptome level. Accordingly, these results allow us to better understand the molecular mechanisms of watermelon in response to drought stress and will facilitate watermelon breeding projects to improve drought tolerance.

  1. Gene expression analysis in response to osmotic stimuli in the intervertebral disc with DNA microarray.

    Science.gov (United States)

    Zhang, Wenzhi; Li, Xu; Shang, Xifu; Zhao, Qichun; Hu, Yefeng; Xu, Xiang; He, Rui; Duan, Liqun; Zhang, Feng

    2013-12-27

    Intervertebral disc (IVD) cells experience a broad range of physicochemical stimuli under physiologic conditions, including alterations in their osmotic environment. At present, the molecular mechanisms underlying osmotic regulation in IVD cells are poorly understood. This study aims to screen genes affected by changes in osmotic pressure in cells of subjects aged 29 to 63 years old, with top-scoring pair (TSP) method. Gene expression data set GSE1648 was downloaded from Gene Expression Omnibus database, including four hyper-osmotic stimuli samples, four iso-osmotic stimuli samples, and three hypo-osmotic stimuli samples. A novel, simple method, referred to as the TSP, was used in this study. Through this method, there was no need to perform data normalization and transformation before data analysis. A total of five pairs of genes ((CYP2A6, FNTB), (PRPF8, TARDBP), (RPS5, OAZ1), (SLC25A3, NPM1) and (CBX3, SRSF9)) were selected based on the TSP method. We inferred that all these genes might play important roles in response to osmotic stimuli and age in IVD cells. Additionally, hyper-osmotic and iso-osmotic stimuli conditions were adverse factors for IVD cells. We anticipate that our results will provide new thoughts and methods for the study of IVD disease.

  2. Swelling, mechanical and friction properties of PVA/PVP hydrogels after swelling in osmotic pressure solution.

    Science.gov (United States)

    Shi, Yan; Xiong, Dangsheng; Liu, Yuntong; Wang, Nan; Zhao, Xiaoduo

    2016-08-01

    The potential of polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) hydrogels as articular cartilage replacements was in vitro evaluated by using a macromolecule-based solution to mimic the osmotic environment of cartilage tissue. The effects of osmotic pressure solution on the morphology, crystallinity, swelling, mechanical and friction properties of PVA/PVP hydrogels were investigated by swelling them in non-osmotic and osmotic pressure solutions. The results demonstrated that swelling ratio and equilibrium water content were greatly reduced by swelling in osmotic solution, and the swelling process was found to present pseudo-Fickian diffusion character. The crystallization degree of hydrogels after swelling in osmotic solution increased more significantly when it compared with that in non-osmotic solution. After swelling in osmotic solution for 28days, the compressive tangent modulus and storage modulus of hydrogels were significantly increased, and the low friction coefficient was reduced. However, after swelling in the non-osmotic solution, the compressive tangent modulus and friction coefficient of hydrogels were comparable with those of as-prepared hydrogels. The better material properties of hydrogels in vivo than in vitro evaluation demonstrated their potential application in cartilage replacement. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. An osmotic model of the growing pollen tube.

    Directory of Open Access Journals (Sweden)

    Adrian E Hill

    Full Text Available Pollen tube growth is central to the sexual reproduction of plants and is a longstanding model for cellular tip growth. For rapid tip growth, cell wall deposition and hardening must balance the rate of osmotic water uptake, and this involves the control of turgor pressure. Pressure contributes directly to both the driving force for water entry and tip expansion causing thinning of wall material. Understanding tip growth requires an analysis of the coordination of these processes and their regulation. Here we develop a quantitative physiological model which includes water entry by osmosis, the incorporation of cell wall material and the spreading of that material as a film at the tip. Parameters of the model have been determined from the literature and from measurements, by light, confocal and electron microscopy, together with results from experiments made on dye entry and plasmolysis in Lilium longiflorum. The model yields values of variables such as osmotic and turgor pressure, growth rates and wall thickness. The model and its predictive capacity were tested by comparing programmed simulations with experimental observations following perturbations of the growth medium. The model explains the role of turgor pressure and its observed constancy during oscillations; the stability of wall thickness under different conditions, without which the cell would burst; and some surprising properties such as the need for restricting osmotic permeability to a constant area near the tip, which was experimentally confirmed. To achieve both constancy of pressure and wall thickness under the range of conditions observed in steady-state growth the model reveals the need for a sensor that detects the driving potential for water entry and controls the deposition rate of wall material at the tip.

  4. An Osmotic Model of the Growing Pollen Tube

    Science.gov (United States)

    Hill, Adrian E.; Shachar-Hill, Bruria; Skepper, Jeremy N.; Powell, Janet; Shachar-Hill, Yair

    2012-01-01

    Pollen tube growth is central to the sexual reproduction of plants and is a longstanding model for cellular tip growth. For rapid tip growth, cell wall deposition and hardening must balance the rate of osmotic water uptake, and this involves the control of turgor pressure. Pressure contributes directly to both the driving force for water entry and tip expansion causing thinning of wall material. Understanding tip growth requires an analysis of the coordination of these processes and their regulation. Here we develop a quantitative physiological model which includes water entry by osmosis, the incorporation of cell wall material and the spreading of that material as a film at the tip. Parameters of the model have been determined from the literature and from measurements, by light, confocal and electron microscopy, together with results from experiments made on dye entry and plasmolysis in Lilium longiflorum. The model yields values of variables such as osmotic and turgor pressure, growth rates and wall thickness. The model and its predictive capacity were tested by comparing programmed simulations with experimental observations following perturbations of the growth medium. The model explains the role of turgor pressure and its observed constancy during oscillations; the stability of wall thickness under different conditions, without which the cell would burst; and some surprising properties such as the need for restricting osmotic permeability to a constant area near the tip, which was experimentally confirmed. To achieve both constancy of pressure and wall thickness under the range of conditions observed in steady-state growth the model reveals the need for a sensor that detects the driving potential for water entry and controls the deposition rate of wall material at the tip. PMID:22615784

  5. Echocardiography in shock management.

    Science.gov (United States)

    McLean, Anthony S

    2016-08-20

    Echocardiography is pivotal in the diagnosis and management of the shocked patient. Important characteristics in the setting of shock are that it is non-invasive and can be rapidly applied.In the acute situation a basic study often yields immediate results allowing for the initiation of therapy, while a follow-up advanced study brings the advantage of further refining the diagnosis and providing an in-depth hemodynamic assessment. Competency in basic critical care echocardiography is now regarded as a mandatory part of critical care training with clear guidelines available. The majority of pathologies found in shocked patients are readily identified using basic level 2D and M-mode echocardiography. A more comprehensive diagnosis can be achieved with advanced levels of competency, for which practice guidelines are also now available. Hemodynamic evaluation and ongoing monitoring are possible with advanced levels of competency, which includes the use of colour Doppler, spectral Doppler, and tissue Doppler imaging and occasionally the use of more recent technological advances such as 3D or speckled tracking.The four core types of shock-cardiogenic, hypovolemic, obstructive, and vasoplegic-can readily be identified by echocardiography. Even within each of the main headings contained in the shock classification, a variety of pathologies may be the cause and echocardiography will differentiate which of these is responsible. Increasingly, as a result of more complex and elderly patients, the shock may be multifactorial, such as a combination of cardiogenic and septic shock or hypovolemia and ventricular outflow obstruction.The diagnostic benefit of echocardiography in the shocked patient is obvious. The increasing prevalence of critical care physicians experienced in advanced techniques means echocardiography often supplants the need for more invasive hemodynamic assessment and monitoring in shock.

  6. Pediatric Toxic Shock Syndrome

    Directory of Open Access Journals (Sweden)

    Jennifer Yee

    2017-09-01

    Full Text Available Audience: This scenario was developed to educate emergency medicine residents on the diagnosis and management of a pediatric patient with toxic shock syndrome. The case is also appropriate for teaching of medical students and advanced practice providers, as well as a review of the principles of crisis resource management, teamwork, and communication. Introduction: Toxic shock syndrome is a low-frequency, high-acuity scenario requiring timely identification and aggressive management. If patients suffering from this condition are managed incorrectly, they may progress into multi-organ dysfunction and potentially death. Toxic shock syndrome has been associated with Streptococcus and Staphylococcus aureus (Staph. Approximately half of Staph cases are associated with menstruation, which was first described in the 1970s-1980s and was associated with the use of absorbent tampons.1 Group A Streptococcus may cause complications such as necrotizing fasciitis and gangrenous myositis.2 Pediatric patients may present critically ill from toxic shock syndrome. Providers need to perform a thorough history and physical exam to discern the source of infection. Management requires aggressive care with antibiotics and IV fluids. Objectives: By the end of this simulation session, the learner will be able to: 1 Recognize toxic shock syndrome. 2 Review the importance of a thorough physical exam. 3 Discuss management of toxic shock syndrome, including supportive care and the difference in antibiotic choices for streptococcal and staphylococcal toxic shock syndrome. 4 Appropriately disposition a patient suffering from toxic shock syndrome. 5 Communicate effectively with team members and nursing staff during a resuscitation of a critically ill patient. Method: This session was conducted using high-fidelity simulation, followed by a debriefing session and lecture on toxic shock syndrome.

  7. Imploding conical shock waves

    Science.gov (United States)

    Paton, R. T.; Skews, B. W.; Rubidge, S.; Snow, J.

    2013-07-01

    The behaviour of conical shock waves imploding axisymmetrically was first studied numerically by Hornung (J Fluid Mech 409:1-12, 2000) and this prompted a limited experimental investigation into these complex flow patterns by Skews et al. (Shock Waves 11:323-326, 2002). Modification of the simulation boundary conditions, resulting in the loss of self-similarity, was necessary to image the flow experimentally. The current tests examine the temporal evolution of these flows utilising a converging conical gap of fixed width fed by a shock wave impinging at its entrance, supported by CFD simulations. The effects of gap thickness, angle and incident shock strength were investigated. The wave initially diffracts around the outer lip of the gap shedding a vortex which, for strong incident shock cases, can contain embedded shocks. The converging shock at exit reflects on the axis of symmetry with the reflected wave propagating outwards resulting in a triple point developing on the incident wave together with the associated shear layer. This axisymmetric shear layer rolls up into a mushroom-shaped toroidal vortex ring and forward-facing jet. For strong shocks, this deforms the Mach disk to the extent of forming a second triple point with the primary shock exhibiting a double bulge. Separate features resembling the Richtmeyer-Meshkov and Kelvin-Helmholtz instabilities were noted in some tests. Aside from the incident wave curvature, the reflection patterns demonstrated correspond well with the V- and DV-types identified by Hornung although type S was not clearly seen, possibly due to the occlusion of the reflection region by the outer diffraction vortex at these early times. Some additional computational work explicitly exploring the limits of the parameter space for such systems has demonstrated the existence of a possible further reflection type, called vN-type, which is similar to the von Neumann reflection for plane waves. It is recommended that the parameter space be

  8. The safety of osmotically acting cathartics in colonic cleansing

    DEFF Research Database (Denmark)

    Nyberg, Caroline; Hendel, J.; Nielsen, O.H.

    2010-01-01

    hyperphosphatemia and irreversible kidney damage owing to acute phosphate nephropathy, have been reported after use of sodium-phosphate-based products. The aim of this Review is to provide an update on the potential safety issues related to the use of osmotically acting cathartics, especially disturbances of renal...... function and water and electrolyte balance. The available evidence indicates that PEG-ELS-based products are the safest option. Magnesium-citrate-based, hypertonic products should be administered with caution to elderly individuals and patients who are prone to develop disturbances in water and electrolyte...

  9. Sporadic hypokalemic paralysis caused by osmotic diuresis in diabetes mellitus.

    Science.gov (United States)

    Vishnu, Venugopalan Y; Kattadimmal, Anoop; Rao, Suparna A; Kadhiravan, Tamilarasu

    2014-07-01

    A wide variety of neurological manifestations are known in patients with diabetes mellitus. We describe a 40-year-old man who presented with hypokalemic paralysis. On evaluation, we found that the cause of the hypokalemia was osmotic diuresis induced by marked hyperglycemia due to undiagnosed diabetes mellitus. The patient had an uneventful recovery with potassium replacement, followed by glycemic control with insulin. Barring a few instances of symptomatic hypokalemia in the setting of diabetic emergencies, to our knowledge uncomplicated hyperglycemia has not been reported to result in hypokalemic paralysis. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Artificial neural network model of pork meat cubes osmotic dehydration

    OpenAIRE

    Pezo, Lato L.; Ćurčić, Biljana Lj.; Filipović, Vladimir S.; Nićetin, Milica R.; Koprivica, Gordana B.; Mišljenović, Nevena M.; Lević, Ljubinko B.

    2013-01-01

    Mass transfer of pork meat cubes (M. triceps brachii), shaped as 1x1x1 cm, during osmotic dehydration (OD) and under atmospheric pressure was investigated in this paper. The effects of different parameters, such as concentration of sugar beet molasses (60-80%, w/w), temperature (20-50ºC), and immersion time (1-5 h) in terms of water loss (WL), solid gain (SG), final dry matter content (DM), and water activity (aw), were investigated using experimental results. Five artificial neural net...

  11. A temporary flagellate (mastigote) stage in the vahlkampfiid amoeba Willaertia magna and its possible evolutionary significance.

    Science.gov (United States)

    Robinson, B S; Christy, P E; De Jonckheere, J F

    1989-01-01

    A temporary flagellate (mastigote) stage has been observed in several isolates of the vahlkampfiid amoeba Willaertia magna. In an Australian isolate studied in detail, flagellates appeared synchronously, although later than in Naegleria fowleri or N. lovaniensis under similar conditions (half-maximal time, t50 = 168 min at 37 degrees C). The flagellates initially have four flagella and lack a cytostome, but undergo several successive divisions, the first of them synchronous, resulting in progressive reduction in cell volume. New flagella appear during and after division, and the number of flagella in daughter cells of later divisions is rather variable. Comparison of these observations with descriptions of other amoeboflagellates confirms that Willaertia is a valid genus. A likely sequence of morphological changes in the evolution of Willaertia and Naegleria from a hypothetical ancestral vahlkampfiid is proposed.

  12. The Laredo strain and other 'Entamoeba histolytica-like' amoebae are Entamoeba moshkovskii.

    Science.gov (United States)

    Clark, C G; Diamond, L S

    1991-05-01

    A small number of Entamoeba isolates from humans, the best known of which is the 'Laredo' strain, have the ability to grow at room temperature. This peculiarity, along with other characteristics, distinguishes the strains from the human pathogen E. histolytica despite their being morphologically inseparable. In contrast, these 'E. histolytica-like' strains share several features with E. moshkovskii, which is most frequently isolated from polluted water. To examine the taxonomic relationships among these morphologically similar organisms, we have used polymerase chain reaction amplification of the small subunit ribosomal RNA gene combined with restriction fragment length polymorphism analysis, 'riboprinting'. The results clearly show that the 'E. histolytica-like' amoebae are indeed strains of E. moshkovskii, and not closely related to E. histolytica.

  13. Bioaccumulation of pathogenic bacteria and amoeba by zebra mussels and their presence in watercourses.

    Science.gov (United States)

    Mosteo, R; Goñi, P; Miguel, N; Abadías, J; Valero, P; Ormad, M P

    2016-01-01

    Dreissena polymorpha (the zebra mussel) has been invading freshwater bodies in Europe since the beginning of the nineteenth century. Filter-feeding organisms can accumulate and concentrate both chemical and biological contaminants in their tissues. Therefore, zebra mussels are recognized as indicators of freshwater quality. In this work, the capacity of the zebra mussel to accumulate human pathogenic bacteria and protozoa has been evaluated and the sanitary risk associated with their presence in surface water has also been assessed. The results show a good correlation between the pathogenic bacteria concentration in zebra mussels and in watercourses. Zebra mussels could therefore be used as an indicator of biological contamination. The bacteria (Escherichia coli, Enterococcus spp., Pseudomonas spp., and Salmonella spp.) and parasites (Cryptosporidium oocysts and free-living amoebae) detected in these mussels reflect a potential sanitary risk in water.

  14. Contribution to the problem of the so-called nonpathogenic amoebae in the intestine of man.

    Science.gov (United States)

    Cerva, L; Kliment, V

    1978-01-01

    Among 10,418 patients of a Prague hospital, a plain infection with intestinal parasitic protozoans was identified in 1,319 persons (12.7%). Of these, 3.5% were infested with Giardia intestinalis, 0.3% with Entamoeba histolytica forma minuta, 5.7% with Endolimax nana. We evaluated the frequency of findings of protozoans in various clinical diagnoses. A statistically significant increase in frequency was recorded for E. nana in diagnoses of eosinophilia, giardiasis, amoebiasis and helminthiasis. A slight increase above the average was found for Entamoeba coli in diagnoses of giardiasis and helminthiasis. Most cases of infection with Entamoeba histolytica were associated with a stay abroad. No increase in the frequency of these protozoans was recorded for patients with diarrhea. An analysis of the results indicated that a nonpathogenic amoeba might participate in the origin of intestinal disorders in man.

  15. Examination of thermally polluted water for free living amoebae and testing for their possible pathogenic properties

    Energy Technology Data Exchange (ETDEWEB)

    Janitschke, K.; Lichy, S.; Westphal, C.

    1982-05-01

    Water and mud samples were collected from canals and rivers which were adjacent to outlets discharging warm water of 3 power plants in Berlin. Downstream samples from 1 bathing resort were also collected. Free living amoebae were isolated from 138 water and 69 mud samples. From these respectively 156 and 73 strains could be cultured and were administered intranasally to mice for pathogenicity tests. Two Acanthamoeba strains from water and 7 from mud could be reisolated from mouse brain and or lungs, although no pathological disorders could be observed. Five Naegleria strains were negative in mouse inoculation tests. Four Acanthamoeba strains which were positive in mice were cultured at + 45 degrees C; no cytopathogenic effects were observed in tissue cultures. Acanthamoeba infective for mice could also be isolated from samples at low water temperatures. Further investigations have to show, whether changes in virulence of amoebic strains are of significance and therefore for epidemiology and pathogenicity in man.

  16. Reaching an entrepreneurial management system of amoebas. A qualitative insight into the European experiences

    Directory of Open Access Journals (Sweden)

    Urban Wiesław

    2016-03-01

    Full Text Available The aim of the study is an assessment of the Amoeba Management System (AMS introduction advancements in some European companies. The study takes the practically focused research approach. The approaches, achievements and phases whilst introducing the AMS principles by companies are observed and critically assessed. First insight into the challenges of AMS introduction is taken basing on critical study of the literature output. The scientific studies and managerial publications are taken into consideration. The empirical part of the study is based on the qualitative approach. A multiple case study methodology is employed. The research objects are three companies, one of them operates in Sweden, the next two in Poland. Each of them have different experiences in AMS implementation, they also manifest different management styles and habits. The study demonstrates that AMS is a very prospective management methodology which can support companies in employees commitment during their journey towards operational excellence. The analysis results show different motivations for AMS introduction as well as different development paths, these are harmonized with different management styles in companies and culture occurring in countries. The study is particularly valuable because this is one of the first empirical investigations of AMS implementation in European companies. In the field of theory the study proposes the four level scale for amoebas system maturity. This scale allows to classify companies following AMS principles and, at the same time, this scale is also the kind of path of AMS implementation. The study points out basic tools for companies which support AMS implementation. These tools are already known in management literature, but experience of investigated companies shows that they are fundamental for successful AMS implementation.

  17. Life shocks and homelessness.

    Science.gov (United States)

    Curtis, Marah A; Corman, Hope; Noonan, Kelly; Reichman, Nancy E

    2013-12-01

    We exploited an exogenous health shock-namely, the birth of a child with a severe health condition-to investigate the effect of a life shock on homelessness in large cities in the United States as well as the interactive effects of the shock with housing market characteristics. We considered a traditional measure of homelessness, two measures of housing instability thought to be precursors to homelessness, and a combined measure that approximates the broadened conceptualization of homelessness under the 2009 Homeless Emergency Assistance and Rapid Transition to Housing Act (2010). We found that the shock substantially increases the likelihood of family homelessness, particularly in cities with high housing costs. The findings are consistent with the economic theory of homelessness, which posits that homelessness results from a conjunction of adverse circumstances in which housing markets and individual characteristics collide.

  18. Electrical Shock: First Aid

    Science.gov (United States)

    ... using a dry, nonconducting object made of cardboard, plastic or wood. Begin CPR if the person shows ... org/first-aid/first-aid-electrical-shock/basics/art-20056695 . Mayo Clinic Footer Legal Conditions and Terms ...

  19. Shock Waves in Supernova Ejecta

    Science.gov (United States)

    Raymond, J. C.

    2018-02-01

    Astrophysical shock waves are a major mechanism for dissipating energy, and by heating and ionizing the gas they produce emission spectra that provide valuable diagnostics for the shock parameters, for the physics of collisionless shocks, and for the composition of the shocked material. Shocks in SN ejecta in which H and He have been burned to heavier elements behave differently than shocks in ordinary astrophysical gas because of their very large radiative cooling rates. In particular, extreme departures from thermal equilibrium among ions and electrons and from ionization equilibrium may arise. This paper discusses the consequences of the enhanced metal abundances for the structure and emission spectra of those shocks.

  20. Unlimited Relativistic Shock Surfing Acceleration

    International Nuclear Information System (INIS)

    Ucer, D.; Shapiro, V. D.

    2001-01-01

    Nonrelativistic shock surfing acceleration at quasiperpendicular shocks is usually considered to be a preacceleration mechanism for slow pickup ions to initiate diffusive shock acceleration. In shock surfing, the particle accelerates along the shock front under the action of the convective electric field of the plasma flow. However, the particle also gains kinetic energy normal to the shock and eventually escapes downstream. We consider the case when ions are accelerated to relativistic velocities. In this case, the ions are likely to be trapped for infinitely long times, because the energy of bounce oscillations tends to decrease during acceleration. This suggests the possibility of unlimited acceleration by shock surfing

  1. Pediatric Toxic Shock Syndrome

    OpenAIRE

    Yee, Jennifer; King, Andrew

    2017-01-01

    Audience: This scenario was developed to educate emergency medicine residents on the diagnosis and management of a pediatric patient with toxic shock syndrome. The case is also appropriate for teaching of medical students and advanced practice providers, as well as a review of the principles of crisis resource management, teamwork, and communication. Introduction: Toxic shock syndrome is a low-frequency, high-acuity scenario requiring timely identification and aggressive management....

  2. Prevalence of potentially pathogenic free-living amoebae from Acanthamoeba and Naegleria genera in non-hospital, public, internal environments from the city of Santos, Brazil

    Directory of Open Access Journals (Sweden)

    Lais Helena Teixeira

    Full Text Available Acanthamoeba and Naegleria species are free-living amoebae (FLA found in a large variety of natural habitats. The prevalence of such amoebae was determined from dust samples taken from public non-hospital internal environments with good standards of cleanliness from two campuses of the same University in the city of Santos (SP, Brazil, and where young and apparently healthy people circulate. The frequency of free-living amoebae in both campuseswas 39% and 17% respectively, with predominance of the genus Acanthamoeba. On the campus with a much larger number of circulating individuals, the observed frequency of free-living amoebae was 2.29 times larger (P< 0.00005. Two trophozoite forms of Naegleria fowleri, are the only species of this genus known to cause primary amoebian meningoencephalitis, a rare and non-opportunistic infection. We assume that the high frequency of these organisms in different internal locations represents some kind of public health risk.

  3. Osmotic and activity coefficients of triorganophosphates in n-octane

    International Nuclear Information System (INIS)

    Sagert, N.H.; Lau, D.W.P.

    1982-01-01

    Vapour pressure osmometry was used to measure osmotic coefficients for tributylphosphate (TBP), tricresylphosphate (TCP), and triethylhexylphosphate (THEP) in n-octane at 30, 40, 50, and 60 0 C and at molalities up to 0.3 mol/kg. Activity coefficients and excess thermodynamic properties (unsymmetrical definition) were calculated from these osmotic coefficients. At 30 0 C, the excess Gibbs free energies for 0.1 mol of solute in 1.0 kg n-octane were -42 J, -66 J, and -20 J for TBP, TCP, and TEHP, respectively. The more ideal behavior of the TEHP-octane system is attributed to the increasing importance of hydrocarbon-hydrocarbon interactions as the chain length is increased. The excess enthalpies for 0.1 mol of solute in 1.0 kg of solvent were -100 J, and -300 J, and -150 J for TBP, TCP, and TEHP, respectively. Thus, association of these solutes arises primarily from entropic effects. Our data could generally be accommodated adequately by postulating association of monomers into dimmers. The exception was TCP at lower temperatures, where more complex models were required

  4. Does osmotic distillation change the isotopic relation of wines?

    Directory of Open Access Journals (Sweden)

    Schmitt Matthias

    2014-01-01

    Full Text Available Currently partial alcohol reduction of wine is in the focus of research worldwide. There are several technologies available to achieve this target. These techniques are either based on distilling or membrane processes. Osmotic distillation, one of the possibilities, is a quite modern membrane process that can be used. During that process, wine is pumped in counter flow to water along a micro porous, hydrophobic membrane. The volatile components of the wine can permeate that membrane and are dissolved in water. The driving force of that process is the vapor pressure difference between the volatiles on the wine and water side of the membrane. The aim of this work was to determine if the alcohol reduction by osmotic distillation can change the isotopic relation in a wine. Can this enological practice change the composition of a wine in a way that an illegal water addition is simulated? Different wines were reduced by 2% alcohol v/v with varying process parameters. The isotopic analysis of the O 16/18 ratio in the wine were performed according to the OIV methods (353/2009 These analyses showed that the isotopic ratio is modified by an alcohol reduction of 2% v/v in a way that corresponds to an addition of 4–5% of external water.

  5. Augmentation of peristaltic microflows through electro-osmotic mechanisms

    International Nuclear Information System (INIS)

    Chakraborty, Suman

    2006-01-01

    The present work aims to theoretically establish that the employment of an axial electric field can substantially augment the rate of microfluidic transport occurring in peristaltic microtubes. For theoretical analysis, shape evolution of the tube is taken to be arbitrary, except for the fact that the characteristic wavelength is assumed to be significantly greater than the average radius of cross section. First, expressions for the velocity profile within the tube are derived and are subsequently utilized to obtain variations in the net flow rate across the same, as a function of the pertinent system parameters. Subsequently, the modes of interaction between the electro-osmotic and peristaltic mechanisms are established through the variations in the time-averaged flow rates for zero pressure rise and the pressure rise for zero time-averaged flow rates, as expressed in terms of the occlusion number, characteristic electro-osmotic velocity and the peristaltic wave speed. From the simulation predictions, it is suggested that a judicious combination of peristalsis and an axial electrokinetic body force can drastically enhance the time-averaged flow rate, provided that the occlusion number is relatively small

  6. Thermal and Osmotic Tolerance of 'Irukandji' Polyps: Cubozoa; Carukia barnesi.

    Directory of Open Access Journals (Sweden)

    Robert Courtney

    Full Text Available This research explores the thermal and osmotic tolerance of the polyp stage of the Irukandji jellyfish Carukia barnesi, which provides new insights into potential polyp habitat suitability. The research also targets temperature, salinity, feeding frequency, and combinations thereof, as cues for synchronous medusae production. Primary findings revealed 100% survivorship in osmotic treatments between 19 and 46‰, with the highest proliferation at 26‰. As salinity levels of 26‰ do not occur within the waters of the Great Barrier Reef or Coral Sea, we conclude that the polyp stage of C. barnesi is probably found in estuarine environments, where these lower salinity conditions commonly occur, in comparison to the medusa stage, which is oceanic. Population stability was achieved at temperatures between 18 and 31°C, with an optimum temperature of 22.9°C. We surmise that C. barnesi polyps may be restricted to warmer estuarine areas where water temperatures do not drop below 18°C. Asexual reproduction was also positively correlated with feeding frequency. Temperature, salinity, feeding frequency, and combinations thereof did not induce medusae production, suggesting that this species may use a different cue, possibly photoperiod, to initiate medusae production.

  7. Sterol biosynthesis via cycloartenol and other biochemical features related to photosynthetic phyla in the amoeba Naegleria lovaniensis and Naegleria gruberi.

    Science.gov (United States)

    Raederstorff, D; Rohmer, M

    1987-04-15

    The sterols and sterol precursors of two amoebae of the genus Naegleria, Naegleria lovaniensis and Naegleria gruberi were investigated. Cycloartenol, the sterol precursor in photosynthetic organisms, is present in both amoebae. In N. lovaniesis, it is accompanied by lanosterol and parkeol, as well as by the 24,25-dihydro derivatives of these triterpenes. One of the most striking features of these amoebae is the accumulation of 4 alpha-methylsterols which are present in similar amounts as those of 4,4-desmethylsterols (3-5 mg/g, dry weight). 4 alpha-Methylergosta-7,22-dienol was identified as a new compound. Ergosterol was the major 4,4-desmethylsterol, accompanied by small amounts of C27 and other C28 sterols. Treatment of N. lovaniensis with fenpropimorph modified the sterol pattern of this amoeba and inhibited its growth. This fungicide, known to inhibit steps of sterol biosynthesis in fungi and plants, induced the disappearance of 4 alpha-methyl-delta 7-sterols and the appearance of the unusual delta 6,8,22-ergostatrienol as in A. polyphaga. These results might be explained by a partial inhibition of the delta 8----delta 7 isomerase, the small amounts of delta 7-sterols formed being converted into ergosterol which is still present in fenpropimorph-exposed cells. De novo sterol biosynthesis in N. lovaniensis was shown by incorporation of [1-14C]acetate into sterols and sterol precursors, especially cycloartenol. Lanosterol and parkeol were not significantly labelled. Furthermore, [3-3H]squalene epoxide was efficiently cyclized by a cell-free system of this amoeba into cycloartenol, and again no significant radioactivity was detected in lanosterol and parkeol. This shows that cycloartenol, the sterol precursor in plants and algae, is also the sterol precursor in Naegleria species, and that these amoebae, like A. polyphaga, are related by some biosynthetic pathways to photosynthetic phyla. Lanosterol, the sterol precursor in non-photosynthetic phyla (animal and

  8. Water osmotic absorption in Coleus blumei plants under salinity stress

    Directory of Open Access Journals (Sweden)

    José Ozinaldo Alves de Sena

    2006-11-01

    Full Text Available Three month old Coleus blumei plants in pots were treated with different NaCl concentrations: 0.00, 0.25, 0.50 and 1.00%. To determine the water osmotic absorption, the plants had their stems cut at 10 cm from the soil surface. The remaining stems were linked to glass tubes by flexible rubber tubes. Readings of the water column level in the glass tubes were performed at each 30 minutes, corresponding to the water osmotic absorption, with a total of eleven readings. Other Coleus blumei, with the same age, received the NaCl concentrations, and were evaluated under field conditions in terms of transpiration and stomatal resistance. A randomized complete block analysis was used with five replications. An increase of osmotic absorption was verified for all treatments up to three hours after application. Then a proportional reversion of osmotic absorption to the increases on saline concentration was observed, with a higher effect in the treatment with NaCl 1.00%, showing the increase of water loss by the roots. During this period time, the treatment showed a normal linear growth of the osmotic absorption. Transpiration was reduced proportionally to the increase of salinity concentration.Mudas envasadas de Coleus blumei, com três meses de idade, foram submetidas a diferentes concentrações de cloreto de sódio (NaCl: 0,00; 0,25; 0,50 e 1,00%. Visando determinar a absorção osmótica, as mudas tiveram seus caules cortados a 10 cm acima do solo. Os caules remanescentes foram interligados a tubos de vidro por tubos flexíveis de borracha. Foram feitas leituras (cm a cada 30 minutos dos níveis das colunas de água nos capilares, correspondentes às absorções osmóticas de água, sendo ao todo realizadas onze leituras. Em outro momento, mudas de C. blumei, com a mesma idade das anteriores, receberam as mesmas concentrações de NaCl descritas anteriormente, e, ao ar livre, foram avaliadas em termos de transpiração e resistência estomática, usando

  9. First Record of Potentially Pathogenic Amoeba Vermamoeba vermiformis (Lobosea: Gymnamoebia) Isolated from a Freshwater of Dokdo Island in the East Sea, Korea

    OpenAIRE

    Jong Soo Park

    2016-01-01

    Vermamoeba vermiformis is a very important free-living amoeba for human health in association with Legionnaires’ disease and keratitis. This interesting amoeba was firstly isolated from a freshwater of Dokdo (island), which was historically used for drinking water. Trophozoites and cyst forms of V. vermiformis strain MG1 are very similar to previous reported species. Trophozoites of V. vermiformis strain MG1 showed cylindrical shape with prominent anterior hyaline region. The average ratio of...

  10. Colloid osmotic pressure in decompensated cirrhosis. A 'mirror image' of portal venous hypertension

    DEFF Research Database (Denmark)

    Henriksen, Jens Henrik Sahl

    1985-01-01

    in the interstitial space and ascitic fluid is related to and most likely secondary to the elevated portal pressure in decompensated cirrhosis. Effective colloid osmotic pressure may therefore be regarded as a 'mirror image' of transmural portal pressure. The role of colloid osmotic pressure in the genesis...

  11. Effect of osmotic stress on in vitro propagation of Musa sp. (Malbhog ...

    African Journals Online (AJOL)

    This study demonstrates up to 36% reduced microbial contamination in aseptic culture establishment and subsequent micropropagation due to osmotic stress induction in the banana suckers. Osmotic stress was induced by keeping the freshly collected suckers in shade and measuring fresh weight at 0, 7, 14, 21, and 28 ...

  12. Mechanical properties of the collagen network in human articular cartilage as measured by osmotic stress technique

    NARCIS (Netherlands)

    Basser, P.J.; Schneiderman, R.; Bank, R.A.; Wachtel, E.; Maroudas, A.

    1998-01-01

    We have used an isotropic osmotic stress technique to assess the swelling pressures of human articular cartilage over a wide range of hydrations in order to determine from these measurements, for the first time, the tensile stress in the collagen network, P(c), as a function of hydration. Osmotic

  13. Influence of osmotic pressure changes on the opening of existing cracks in 2 intervertebral disc models

    NARCIS (Netherlands)

    Wognum, Silvia; Huyghe, Jacques M.; Baaijens, Frank P. T.

    2006-01-01

    An experimental hydrogel model and a numerical mixture model were used to investigate why the disc herniates while osmotic pressure is decreasing. To investigate the influence of decreasing osmotic pressure on the opening of cracks in the disc. In the degeneration process, the disc changes structure

  14. The osmotic pressure of 3He-4He mixtures along the phase separation curve

    NARCIS (Netherlands)

    van de Klundert, L.J.M.; Bos, M.R.E.; van der Meij, J.A.M.; Steffens, H.A.

    1977-01-01

    The osmotic pressure of 3He-4He mixtures was measured along the phase separation curve at temperatures up to 500 mK by balancing it with the fountain pressure of pure 4He. The usefullness of the secondary osmotic pressure thermometer was reinvestigated.

  15. The dependence of molecular transmembrane electrotransfer efficiency on medium conductivity and osmotic pressure

    OpenAIRE

    Jakutavičiūtė, Milda; Ruzgys, Paulius; Šatkauskas, Saulius

    2014-01-01

    The electrotransfer efficiency was evaluated for different external medium conductivities, osmotic pressures and electric pulse voltages. It was found that increase in conductivity or decrease in electric pulse strength decreases electrotransfer efficiency. Decrease in osmotic pressure tends to decrease electrotransfer efficiency.

  16. Optimum condition of producing crisp osmotic banana using superheated steam puffing.

    Science.gov (United States)

    Tabtiang, Surapit; Prachayawarakorn, Somkiat; Soponronnarit, Somchart

    2017-03-01

    Puffing can improve textural property of snacks. Nevertheless, high temperature puffing accelerates non-enzymatic browning reactions. The osmotic treatment using sucrose solution potentially retards the browning, but the high amount of sucrose gain causes hard texture. The objective of this work was therefore to study the effects of osmotic time, puffing time and puffing temperature on banana qualities such as colour, shrinkage and textural property. The experimental results showed that puffing temperature, puffing time and osmotic time significantly affected colour, shrinkage and textual properties. The optimisation using response surface methodology was used for a trade-off between colour and textural properties. To obtain a good quality product, the puffed osmotic banana should be operated at the osmotic time of 43 min and puffing temperature of 220 °C and puffing time of 2 min. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  17. Colloid osmotic pressure in decompensated cirrhosis. A 'mirror image' of portal venous hypertension

    DEFF Research Database (Denmark)

    Henriksen, Jens Henrik Sahl

    1985-01-01

    Colloid osmotic pressure in plasma (IIP) and ascitic fluid (IIA) and hydrostatic pressures in the hepatoportal system were measured simultaneously in 20 patients with decompensated cirrhosis. IIP was significantly decreased (mean, 21 mm Hg, versus normal, 30 mm Hg; P less than 0.01), and IIA....../IIP (r = -0.77, P less than 0.001). WHV--IVCP was in most patients in the same order as and closely correlated to effective colloid osmotic pressure (IIP--IIA) (r = 0.88, P less than 0.001). No relationship was found between WHV--IVCP and IIP. The results indicate that a fall in colloid osmotic pressure...... in the interstitial space and ascitic fluid is related to and most likely secondary to the elevated portal pressure in decompensated cirrhosis. Effective colloid osmotic pressure may therefore be regarded as a 'mirror image' of transmural portal pressure. The role of colloid osmotic pressure in the genesis...

  18. Growth regulation of Legionella Pneumophila in biofilms and amoebae; Wachstumsregulation von Legionella Pneumophila in Biofilmen und Amoeben

    Energy Technology Data Exchange (ETDEWEB)

    Hilbi, H.

    2006-07-01

    This final report for the Swiss Federal Office of Energy (SFOE) presents the results of studies made on the regulation of the growth of Legionella Pneumophila bacteria in biofilms and amoebae. In a first project, the formation of biofilms by Legionella Pneumophila bacteria was analysed in static and dynamic systems using a complex growth medium. Under static and dynamic clinical and environmental conditions, the adherence of the biofilms on polystyrene tissue was studied. This was also examined under dynamic flow conditions. In a second part of the project, the regulation of growth of Legionella Pneumophila in amoebae was examined in that changes were made to the genome of the bacteria. The importance of the work for the de-activation of Legionella Pneumophila bacteria in biofilms is noted in the conclusions of the report.

  19. Characterization of the adaptive response and growth upon hyperosmotic shock in Saccharomyces cerevisiae.

    Science.gov (United States)

    Parmar, Jignesh H; Bhartiya, Sharad; Venkatesh, K V

    2011-04-01

    Molecular and physiological details of osmoadaptation in yeast Saccharomyces cerevisiae are well characterized. It is well known that a cell, upon osmotic shock, delays its growth, produces a compatible solute like glycerol in yeast to maintain the osmotic equilibrium. Many genes are regulated by the hyperosmolarity glycerol (HOG) singling pathway, some of which in turn control the carbon flux in the glycolytic pathway for glycerol synthesis and reduced growth. The whole process of survival of cells under hyperosmotic stress is controlled at multiple levels in signaling and metabolic pathways. To better understand the multi-level regulations in yeast to osmotic shock, a mathematical model is formulated which integrates the growth and the osmoadaptation process. The model included the HOG pathway which consists of Sho1 and Sln1 signaling branches, gene regulation, metabolism and cell growth on glucose and ethanol. Experiments were performed to characterize the effect of various concentrations of salt on the wild-type and mutant strains. The model was able to successfully predict the experimental observations for both the wild-type and mutant strains. Further, the model was used to analyze the effects of various regulatory mechanisms prevalent in the signaling and metabolic pathways which are essential in achieving optimum growth in a saline medium. The analysis demonstrated the relevance of the combined effects of regulation at several points in the signaling and metabolic pathways including activation of GPD1 and GPD2, inhibition of PYK and PDC1, closure of the Fps1 channel, volume effect on the glucose uptake rate, downregulation of ethanol synthesis and upregulation of ALD6 for acetate synthesis. The analysis demonstrated that these combined effects orchestrated the phenomena of adaptation to osmotic stress in yeast.

  20. Fecal osmotic gap and pH in experimental diarrhea of various causes.

    Science.gov (United States)

    Eherer, A J; Fordtran, J S

    1992-08-01

    Although the osmotic gap of fecal fluid is often used to distinguish osmotic diarrhea from secretory diarrhea, there has never been a scientific evaluation of the validity of this concept. Similarly, although a low fecal fluid pH value is used to indicate that diarrhea is mediated by carbohydrate malabsorption, the validity of this method is unproven. Therefore, in the present study, diarrhea was induced in normal subjects by different mechanisms and fecal fluid osmotic gap (using an assumed fecal fluid osmolality of 290 mOsm/kg) and pH were measured. In secretory diarrhea caused by phenolphthalein, the osmotic gap was always less than 50 mOsm/kg, whereas in osmotic diarrhea caused by polyethylene glycol, magnesium hydroxide, lactulose, and sorbitol, the osmotic gap always exceeded 50 mOsm/kg. In osmotic diarrhea caused by sodium sulfate, the fecal fluid osmotic gap was less than 50 mOsm/kg, but phenolphthalein-induced secretory diarrhea could be distinguished from sodium sulfate-induced osmotic diarrhea by the fecal chloride concentration. When diarrhea was caused by carbohydrate malabsorption (lactulose or sorbitol), the fecal fluid pH was always less than 5.6 and usually less than 5.3; by contrast, other causes of diarrhea rarely caused a fecal pH as low as 5.6 and never caused a pH less than 5.3. It is concluded that measurement of fecal fluid osmotic gap and pH can distinguish various mechanisms of experimental diarrhea in normal subjects. The concepts on which these tests are based are therefore verified experimentally.

  1. Investigation of Heterotrophic Bacteria, Legionella and Free-Living Amoeba in Cooling Tower Samples by FISH and Culture Methods

    OpenAIRE

    Zeybek, Zuhal; Dogruoz Gungor, Nihal; Turetgen, Irfan

    2018-01-01

    Themicroorganisms living in the cooling towers water can affect both human healththrough inhalation of aerosolized water as well as industrial processes. Inorder to analyse such man-made water systems, microbiological tests that cangive results in a short time are needed. In this study, the presence ofheterotrophic bacteria, Legionella bacteria and free - living amoeba, FLA,including Acanthamoeba, in cooling-tower water and biofilm samples wereinvestigated using two different methods, fluores...

  2. Development of a high- versus low-pathogenicity model of the free-living amoeba Naegleria fowleri.

    Science.gov (United States)

    Burri, Denise C; Gottstein, Bruno; Zumkehr, Béatrice; Hemphill, Andrew; Schürch, Nadia; Wittwer, Matthias; Müller, Norbert

    2012-10-01

    Species in the genus Naegleria are free-living amoebae of the soil and warm fresh water. Although around 30 species have been recognized, Naegleria fowleri is the only one that causes primary amoebic meningoencephalitis (PAM) in humans. PAM is an acute and fast progressing disease affecting the central nervous system. Most of the patients die within 1-2 weeks of exposure to the infectious water source. The fact that N. fowleri causes such fast progressing and highly lethal infections has opened many questions regarding the relevant pathogenicity factors of the amoeba. In order to investigate the pathogenesis of N. fowleri under defined experimental conditions, we developed a novel high- versus low-pathogenicity model for this pathogen. We showed that the composition of the axenic growth media influenced growth behaviour and morphology, as well as in vitro cytotoxicity and in vivo pathogenicity of N. fowleri. Trophozoites maintained in Nelson's medium were highly pathogenic for mice, demonstrated rapid in vitro proliferation, characteristic expression of surface membrane vesicles and a small cell diameter, and killed target mouse fibroblasts by both contact-dependent and -independent destruction. In contrast, N. fowleri cultured in PYNFH medium exhibited a low pathogenicity, slower growth, increased cell size and contact-dependent target cell destruction. However, cultivation of the amoeba in PYNFH medium supplemented with liver hydrolysate (LH) resulted in trophozoites that were highly pathogenic in mice, and demonstrated an intermediate proliferation rate in vitro, diminished cell diameter and contact-dependent target cell destruction. Thus, in this model, the presence of LH resulted in increased proliferation of trophozoites in vitro and enhanced pathogenicity of N. fowleri in mice. However, neither in vitro cytotoxicity mechanisms nor the presence of membrane vesicles on the surface correlated with the pathologic potential of the amoeba. This indicated that the

  3. Growth-supporting activity for Legionella pneumophila in tap water cultures and implication of hartmannellid amoebae as growth factors.

    Science.gov (United States)

    Wadowsky, R M; Butler, L J; Cook, M K; Verma, S M; Paul, M A; Fields, B S; Keleti, G; Sykora, J L; Yee, R B

    1988-11-01

    Photosynthetic cyanobacteria, heterotrophic bacteria, free-living amoebae, and ciliated protozoa may support growth of Legionella pneumophila. Studies were done with two tap water cultures (WS1 and WS2) containing L. pneumophila and associated microbiota to characterize growth-supporting activity and assess the relative importance of the microbiota in supporting multiplication of L. pneumophila. The water cultures were incubated in the dark at 35 degrees C. The growth-supporting factor(s) was separated from each culture by filtration through 1-micron-pore-size membrane filters. The retentate was then suspended in sterile tap water. Multiplication of L. pneumophila occurred when both the retentate suspension and the filtrate from either culture were inoculated into sterile tap water. L. pneumophila did not multiply in tap water inoculated with only the filtrate, even though filtration did not reduce the concentration of L. pneumophila or heterotrophic bacteria in either culture. Growth-supporting activity of the retentate suspension from WS1 was inactivated at 60 degrees C but unaffected at 0, 25, and 45 degrees C after 30-min incubations. Filtration experiments indicated that the growth-supporting factor(s) in WS1 was 2 to 5 micron in diameter. Ciliated protozoa were not detected in either culture. Hartmannellid amoebae were conclusively demonstrated in WS2 but not in WS1. L. pneumophila multiplied in tap water inoculated with the amoebae (10(3)/ml) and the 1-micron filtrate of WS2. No multiplication occurred in tap water inoculated with the filtrate only. Growth-supporting activity for L. pneumophila may be present in plumbing systems; hartmannellid amoebae appear to be important determinants of multiplication of L. pneumophila in some tap water cultures.

  4. The Phanerozoic diversification of silica-cycling testate amoebae and its possible links to changes in terrestrial ecosystems

    Science.gov (United States)

    Bosak, Tanja; Lara, Enrique; Mitchell, Edward A.D.

    2015-01-01

    The terrestrial cycling of Si is thought to have a large influence on the terrestrial and marine primary production, as well as the coupled biogeochemical cycles of Si and C. Biomineralization of silica is widespread among terrestrial eukaryotes such as plants, soil diatoms, freshwater sponges, silicifying flagellates and testate amoebae. Two major groups of testate (shelled) amoebae, arcellinids and euglyphids, produce their own silica particles to construct shells. The two are unrelated phylogenetically and acquired biomineralizing capabilities independently. Hyalosphenids, a group within arcellinids, are predators of euglyphids. We demonstrate that hyalosphenids can construct shells using silica scales mineralized by the euglyphids. Parsimony analyses of the current hyalosphenid phylogeny indicate that the ability to “steal” euglyphid scales is most likely ancestral in hyalosphenids, implying that euglyphids should be older than hyalosphenids. However, exactly when euglyphids arose is uncertain. Current fossil record contains unambiguous euglyphid fossils that are as old as 50 million years, but older fossils are scarce and difficult to interpret. Poor taxon sampling of euglyphids has also prevented the development of molecular clocks. Here, we present a novel molecular clock reconstruction for arcellinids and consider the uncertainties due to various previously used calibration points. The new molecular clock puts the origin of hyalosphenids in the early Carboniferous (∼370 mya). Notably, this estimate coincides with the widespread colonization of land by Si-accumulating plants, suggesting possible links between the evolution of Arcellinid testate amoebae and the expansion of terrestrial habitats rich in organic matter and bioavailable Si. PMID:26734499

  5. Surveillance and evaluation of the infection risk of free-living amoebae and Legionella in different aquatic environments.

    Science.gov (United States)

    Ji, Wen-Tsai; Hsu, Bing-Mu; Chang, Tien-Yu; Hsu, Tsui-Kang; Kao, Po-Min; Huang, Kuan-Hao; Tsai, Shiou-Feng; Huang, Yu-Li; Fan, Cheng-Wei

    2014-11-15

    Free-living amoebae (FLA) are ubiquitous in various aquatic environments. Several amoebae species are pathogenic and host other pathogens such as Legionella, but the presence of FLA and its parasites as well as the related infection risk are not well known. In this study, the presence of pathogenic FLA and Legionella in various water bodies was investigated. Water samples were collected from a river, intake areas of drinking water treatment plants, and recreational hot spring complexes in central and southern Taiwan. A total of 140 water samples were tested for the presence of Acanthamoeba spp., Naegleria spp., Vermamoeba vermiformis, and Legionella. In addition, phylogenetic characteristics and water quality parameters were also assessed. The pathogenic genotypes of FLA included Acanthamoeba T4 and Naegleria australiensis, and both were abundant in the hot spring water. In contrast, Legionella pneumophila was detected in different aquatic environments. Among the FLA assessed, V. vermiformis was most likely to coexist with Legionella spp. The total bacteria level was associated with the presence of FLA and Legionella especially in hot spring water. Taken together, FLA contamination in recreational hot springs and drinking water source warrants more attention on potential legionellosis and amoebae infections. Copyright © 2014. Published by Elsevier B.V.

  6. Detection and Molecular Characterization of Potentially Pathogenic Free-living Amoebae from Water Sources in Kish Island, Southern Iran.

    Science.gov (United States)

    Niyyati, Maryam; Lasgerdi, Zohreh; Lorenzo-Morales, Jacob

    2015-01-01

    Amoebic keratitis, a sight-threatening corneal infection, mainly occurs in contact lens wearers who wash their eyes with tap water. The present research was conducted to identify the occurrence of potentially pathogenic free-living amoebae (FLA) in tap water sources on Kish Island, a tourist region in Iran. Amoebae were detected using a culture-enriched method and by polymerase chain reaction (PCR)/sequencing of the diagnostic fragment 3 region of the 18S rRNA gene of Acanthamoeba. In the case of other free-living amoebae species, PCR/sequencing analysis of the 18S rDNA was conducted. Results of this study showed the presence of Acanthamoeba belonging to T3, T4, T5, and T11 genotypes in tap water sources. Additionally, Vermamoebae vermiformis was detected in three water samples. This is the first report of the Acanthamoeba genotypes T3, T4, T5, and T11 and V. vermiformis species in tap water sources in a tourist region in Iran.

  7. Pathogenic free-living amoebae in a closed-loop power plant; risk assessment and risk management

    Energy Technology Data Exchange (ETDEWEB)

    Cabanes, P. [Electricite de France (EDF), 75 - Paris (France). Service Etudes Medicales; Pringuez, E.; Siclet, F.; Khalanski, M. [Electricite de France (EDF), 75 - Paris (France). Direction des Etudes et Recherches; Bard, D. [CEA/Fontenay-aux-Roses, Inst. de Protection et de Surete Nucleaire (IPSN), 92 (France); Pernin, P. [Faculte de Pharmacie de Lyon, 69 (France)

    1998-07-01

    Since 1980, the water used for cooling in French power plants has been tested for pathogenic amoebae, especially Naegleria fowleri, the causative agent of Primary Amoebic Meningoencephalitis (PAM), a rapid fatal disease of the central nervous system. The replacement of brass condensers by stainless steel condensers resulted in increased Naegleria fowleri development, to a density of as much as 3000 l{sup -1} in the Dampierre power plant cooling water. Downstream from Dampierre, the maximum detected density of this amoeba during the summer of 1995 was 80 l{sup -1}, at low river flow. The replacement of a second condenser in 1996 at the same power plant was expected to double the amoebae concentration in the river. The hypothetical PAM risk for swimmers was then predicted to be 10{sup -4} per swim. To reduce the risk continuous chlorination of the closed-loop cooling system was implemented at a free residual chlorine level in the range of 0.3-0.5 mg.l{sup -1}. Naegleria fowleri concentrations decreased immediately and thereafter remained under 4 l{sup -1}. Total residual chlorine and chlorinated organic compounds were also monitored in the evaluation of the environmental impact of this preventive action. (authors)

  8. The Phanerozoic diversification of silica-cycling testate amoebae and its possible links to changes in terrestrial ecosystems

    Directory of Open Access Journals (Sweden)

    Daniel J.G. Lahr

    2015-09-01

    Full Text Available The terrestrial cycling of Si is thought to have a large influence on the terrestrial and marine primary production, as well as the coupled biogeochemical cycles of Si and C. Biomineralization of silica is widespread among terrestrial eukaryotes such as plants, soil diatoms, freshwater sponges, silicifying flagellates and testate amoebae. Two major groups of testate (shelled amoebae, arcellinids and euglyphids, produce their own silica particles to construct shells. The two are unrelated phylogenetically and acquired biomineralizing capabilities independently. Hyalosphenids, a group within arcellinids, are predators of euglyphids. We demonstrate that hyalosphenids can construct shells using silica scales mineralized by the euglyphids. Parsimony analyses of the current hyalosphenid phylogeny indicate that the ability to “steal” euglyphid scales is most likely ancestral in hyalosphenids, implying that euglyphids should be older than hyalosphenids. However, exactly when euglyphids arose is uncertain. Current fossil record contains unambiguous euglyphid fossils that are as old as 50 million years, but older fossils are scarce and difficult to interpret. Poor taxon sampling of euglyphids has also prevented the development of molecular clocks. Here, we present a novel molecular clock reconstruction for arcellinids and consider the uncertainties due to various previously used calibration points. The new molecular clock puts the origin of hyalosphenids in the early Carboniferous (∼370 mya. Notably, this estimate coincides with the widespread colonization of land by Si-accumulating plants, suggesting possible links between the evolution of Arcellinid testate amoebae and the expansion of terrestrial habitats rich in organic matter and bioavailable Si.

  9. Competition between Naegleria fowleri and Free Living Amoeba Colonizing Laboratory Scale and Operational Drinking Water Distribution Systems.

    Science.gov (United States)

    Miller, Haylea C; Wylie, Jason T; Kaksonen, Anna H; Sutton, David; Puzon, Geoffrey J

    2018-03-06

    Free living amoebae (FLA), including pathogenic Naegleria fowleri, can colonize and grow within pipe wall biofilms of drinking water distribution systems (DWDSs). Studies on the interactions between various FLA species in biofilms are limited. Understanding the interaction between FLA and the broader biofilm ecology could help better predict DWDS susceptibility to N. fowleri colonization. The aim of this study was to determine if N. fowleri and other FLAs ( Naegleria, Vermamoeba, Willaertia, and Vahlkampfia spp.) cocolonize DWDS biofilm. FLAs commonly isolated from DWDSs ( N. fowleri, V. vermiformis, and N. lovaniensis) were introduced into laboratory-scale biomonitors to determine the impact of these amoebae on N. fowleri's presence and viability. Over 18 months, a single viable amoebae ( N. fowleri, N. lovaniensis, or V. vermiformis) was detected in each biofilm sample, with the exception of N. lovaniensis and N. fowleri, which briefly cocolonized biofilm following their coinoculation. The analysis of biofilm and bulk water samples from operational DWDSs revealed a similar lack of cocolonization with a single FLA detected in 99% ( n = 242) of samples. Interestingly, various Naegleria spp. did colonize the same DWDS locations but at different times. This knowledge furthers the understanding of ecological factors which enable N. fowleri to colonize and survive within operational DWDSs and could aid water utilities to control its occurrence.

  10. Pathogenic free-living amoebae in a closed-loop power plant; risk assessment and risk management

    International Nuclear Information System (INIS)

    Cabanes, P.; Pernin, P.

    1998-01-01

    Since 1980, the water used for cooling in French power plants has been tested for pathogenic amoebae, especially Naegleria fowleri, the causative agent of Primary Amoebic Meningoencephalitis (PAM), a rapid fatal disease of the central nervous system. The replacement of brass condensers by stainless steel condensers resulted in increased Naegleria fowleri development, to a density of as much as 3000 l -1 in the Dampierre power plant cooling water. Downstream from Dampierre, the maximum detected density of this amoeba during the summer of 1995 was 80 l -1 , at low river flow. The replacement of a second condenser in 1996 at the same power plant was expected to double the amoebae concentration in the river. The hypothetical PAM risk for swimmers was then predicted to be 10 -4 per swim. To reduce the risk continuous chlorination of the closed-loop cooling system was implemented at a free residual chlorine level in the range of 0.3-0.5 mg.l -1 . Naegleria fowleri concentrations decreased immediately and thereafter remained under 4 l -1 . Total residual chlorine and chlorinated organic compounds were also monitored in the evaluation of the environmental impact of this preventive action. (authors)

  11. Detection and Molecular Characterization of Potentially Pathogenic Free-living Amoebae from Water Sources in Kish Island, Southern Iran

    Directory of Open Access Journals (Sweden)

    Maryam Niyyati

    2015-01-01

    Full Text Available Amoebic keratitis, a sight-threatening corneal infection, mainly occurs in contact lens wearers who wash their eyes with tap water. The present research was conducted to identify the occurrence of potentially pathogenic free-living amoebae (FLA in tap water sources on Kish Island, a tourist region in Iran. Amoebae were detected using a culture-enriched method and by polymerase chain reaction (PCR/sequencing of the diagnostic fragment 3 region of the 18S rRNA gene of Acanthamoeba . In the case of other free-living amoebae species, PCR/sequencing analysis of the 18S rDNA was conducted. Results of this study showed the presence of Acanthamoeba belonging to T3, T4, T5, and T11 genotypes in tap water sources. Additionally, Vermamoebae vermiformis was detected in three water samples. This is the first report of the Acanthamoeba genotypes T3, T4, T5, and T11 and V. vermiformis species in tap water sources in a tourist region in Iran.

  12. Ecophysiology of invasive plants: osmotic adjustment and antioxidants.

    Science.gov (United States)

    Pintó-Marijuan, Marta; Munné-Bosch, Sergi

    2013-12-01

    Current research into plant invasiveness often attempts to predict the effect of invasions under future climate change, but most studies only focus on ecological aspects. Understanding ecophysiological responses by characterizing physiological markers such as osmotic adjustment or antioxidant protection indicators will help us to project future invasiveness patterns. In this opinion article, we highlight how the information from physiological measurements can be incorporated into effective management strategies. Furthermore, we propose how combining research strategies of physiologists and ecologists could speed up our understanding of the advantageous mechanisms adopted by invasive species. We suggest that a combined approach would also be of considerable benefit for the development of effective governmental biodiversity conservation policies. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Solute coupled diffusion in osmotically driven membrane processes.

    Science.gov (United States)

    Hancock, Nathan T; Cath, Tzahi Y

    2009-09-01

    Forward osmosis (FO) is an emerging water treatment technology with potential applications in desalination and wastewater reclamation. In FO, water is extracted from a feed solution using the high osmotic pressure of a hypertonic solution that flows on the opposite side of a semipermeable membrane; however, solutes diffuse simultaneously through the membrane in both directions and may jeopardize the process. In this study, we have comprehensively explored the effects of different operating conditions on the forward diffusion of solutes commonly found in brackish water and seawater, and reverse diffusion of common draw solution solutes. Results show that reverse transport of solutes through commercially available FO membranes range between 80 mg to nearly 3,000 mg per liter of water produced. Divalent feed solutes have low permeation rates (less than 1 mmol/m2-hr) while monovalent ions and uncharged solutes exhibit higher permeation. Findings have significant implications on the performance and sustainability of the FO process.

  14. Osmotic pressure induced tensile forces in tendon collagen

    Science.gov (United States)

    Masic, Admir; Bertinetti, Luca; Schuetz, Roman; Chang, Shu-Wei; Metzger, Till Hartmut; Buehler, Markus J.; Fratzl, Peter

    2015-01-01

    Water is an important component of collagen in tendons, but its role for the function of this load-carrying protein structure is poorly understood. Here we use a combination of multi-scale experimentation and computation to show that water is an integral part of the collagen molecule, which changes conformation upon water removal. The consequence is a shortening of the molecule that translates into tensile stresses in the range of several to almost 100 MPa, largely surpassing those of about 0.3 MPa generated by contractile muscles. Although a complete drying of collagen would be relevant for technical applications, such as the fabrication of leather or parchment, stresses comparable to muscle contraction already occur at small osmotic pressures common in biological environments. We suggest, therefore, that water-generated tensile stresses may play a role in living collagen-based materials such as tendon or bone.

  15. The safety of osmotically acting cathartics in colonic cleansing

    DEFF Research Database (Denmark)

    Nyberg, Caroline; Hendel, J.; Nielsen, O.H.

    2010-01-01

    Efficient cleansing of the colon before a colonoscopy or a radiological examination is essential. The osmotically acting cathartics (those given the Anatomical Therapeutic Chemical code A06AD) currently used for this purpose comprise products based on three main substances: sodium phosphate......, combinations of polyethylene glycol and electrolyte lavage solutions (PEG-ELS), and magnesium citrate. All these preparations give adequate cleansing results and have similar profiles in terms of the frequency and type of mild to moderate adverse effects. However, serious adverse events, such as severe...... function and water and electrolyte balance. The available evidence indicates that PEG-ELS-based products are the safest option. Magnesium-citrate-based, hypertonic products should be administered with caution to elderly individuals and patients who are prone to develop disturbances in water and electrolyte...

  16. Morpho-physiological changes in maize seedling sunder osmotic stress

    Directory of Open Access Journals (Sweden)

    Anđelković Violeta

    2012-01-01

    Full Text Available Drought is a major abiotic stress factor limiting crop growth, development and production worldwide. The objective of this study was to evaluate tolerance to osmotic stress of maize seedlings. More than 6,000 accessions from the Maize Research Institute gene bank were tested under controlled drought (at flowering in Egypt, and afterwards in temperate climate (Serbia and Macedonia. Out of 41 drought tolerant accessions in the field, five inbred lines were chosen for laboratory testing, as well as one drought sensitive line. These genotypes were exposed to 4% polyethylene glycol-PEG (Mr 10000 for 24 h and 48 h. Nine-day-old seedlings compared to control conditions were analyzed in root and shoot length, fresh and dry weight and proline content. Results showed reduction in all parameters under stress, while only proline content increased in all PEG treated genotypes compared to control.

  17. Osmotic de-swelling and swelling of latex dispersions

    International Nuclear Information System (INIS)

    Bonnet-Gonnet, Cecile

    1993-01-01

    This research thesis reports the comparison of, on the one hand, direct measurements of de-swelling resistance of latex dispersions obtained by osmotic pressure with, on the other hand, predictions made by models of electrostatic interactions. This resistance is explained in the case of sulphate-stabilised polystyrene particles (direct repulsion between charged particles), and in the case of copolymer (ps-pba) particles covered by an amphiphilic polymer (interactions between surface macromolecules and polymers). The study of de-swelling and swelling cycles highlights the existence of thresholds beyond which the concentrated dispersion has some cohesion. This irreversibility can be modelled by a Van der Waals attraction. The role of hydrophobic forces in latex destabilisation is studied [fr

  18. Osmotic pressure induced tensile forces in tendon collagen.

    Science.gov (United States)

    Masic, Admir; Bertinetti, Luca; Schuetz, Roman; Chang, Shu-Wei; Metzger, Till Hartmut; Buehler, Markus J; Fratzl, Peter

    2015-01-22

    Water is an important component of collagen in tendons, but its role for the function of this load-carrying protein structure is poorly understood. Here we use a combination of multi-scale experimentation and computation to show that water is an integral part of the collagen molecule, which changes conformation upon water removal. The consequence is a shortening of the molecule that translates into tensile stresses in the range of several to almost 100 MPa, largely surpassing those of about 0.3 MPa generated by contractile muscles. Although a complete drying of collagen would be relevant for technical applications, such as the fabrication of leather or parchment, stresses comparable to muscle contraction already occur at small osmotic pressures common in biological environments. We suggest, therefore, that water-generated tensile stresses may play a role in living collagen-based materials such as tendon or bone.

  19. Osmotic therapies added to antibiotics for acute bacterial meningitis.

    Science.gov (United States)

    Wall, Emma Cb; Ajdukiewicz, Katherine Mb; Bergman, Hanna; Heyderman, Robert S; Garner, Paul

    2018-02-06

    Every day children and adults die from acute community-acquired bacterial meningitis, particularly in low-income countries, and survivors risk deafness, epilepsy and neurological disabilities. Osmotic therapies may attract extra-vascular fluid and reduce cerebral oedema, and thus reduce death and improve neurological outcomes.This is an update of a Cochrane Review first published in 2013. To evaluate the effects of osmotic therapies added to antibiotics for acute bacterial meningitis in children and adults on mortality, deafness and neurological disability. We searched CENTRAL (2017, Issue 1), MEDLINE (1950 to 17 February 2017), Embase (1974 to 17 February 2017), CINAHL (1981 to 17 February 2017), LILACS (1982 to 17 February 2017) and registers of ongoing clinical trials (ClinicalTrials.com, WHO ICTRP) (21 February 2017). We also searched conference abstracts and contacted researchers in the field (up to 12 December 2015). Randomised controlled trials testing any osmotic therapy in adults or children with acute bacterial meningitis. Two review authors independently screened the search results and selected trials for inclusion. Results are presented using risk ratios (RR) and 95% confidence intervals (CI) and grouped according to whether the participants received steroids or not. We used the GRADE approach to assess the certainty of the evidence. We included five trials with 1451 participants. Four trials evaluated glycerol against placebo, and one evaluated glycerol against 50% dextrose; in addition three trials evaluated dexamethasone and one trial evaluated acetaminophen (paracetamol) in a factorial design. Stratified analysis shows no effect modification with steroids; we present aggregate effect estimates.Compared to placebo, glycerol probably has little or no effect on death in people with bacterial meningitis (RR 1.08, 95% CI 0.90 to 1.30; 5 studies, 1272 participants; moderate-certainty evidence), but may reduce neurological disability (RR 0.73, 95% CI 0

  20. Interstitial Fibrosis Restricts Osmotic Water Transport in Encapsulating Peritoneal Sclerosis

    Science.gov (United States)

    Morelle, Johann; Sow, Amadou; Hautem, Nicolas; Bouzin, Caroline; Crott, Ralph

    2015-01-01

    Encapsulating peritoneal sclerosis (EPS) is a rare but severe complication of peritoneal dialysis (PD) characterized by extensive fibrosis of the peritoneum. Changes in peritoneal water transport may precede EPS, but the mechanisms and potential predictive value of that transport defect are unknown. Among 234 patients with ESRD who initiated PD at our institution over a 20-year period, 7 subsequently developed EPS. We evaluated changes in peritoneal transport over time on PD in these 7 patients and in 28 matched controls using 3.86% glucose peritoneal equilibration tests. Compared with long-term PD controls, patients with EPS showed early loss of ultrafiltration capacity and sodium sieving before the onset of overt EPS. Multivariate analysis revealed that loss of sodium sieving was the most powerful predictor of EPS. Compared with long-term PD control and uremic peritoneum, EPS peritoneum showed thicker submesothelial fibrosis, with increased collagen density and a greater amount of thick collagen fibers. Reduced osmotic conductance strongly correlated with the degree of peritoneal fibrosis, but not with vasculopathy. Peritoneal fibrosis was paralleled by an excessive upregulation of vascular endothelial growth factor and endothelial nitric oxide synthase, but the expression of endothelial aquaporin-1 water channels was unaltered. Our findings suggest that an early and disproportionate reduction in osmotic conductance during the course of PD is an independent predictor of EPS. This functional change is linked to specific alterations of the collagen matrix in the peritoneal membrane of patients with EPS, thereby validating the serial three-pore membrane/fiber matrix and distributed models of peritoneal transport. PMID:25636412

  1. Life Shocks and Homelessness

    Science.gov (United States)

    Corman, Hope; Noonan, Kelly; Reichman, Nancy E.

    2014-01-01

    We exploited an exogenous health shock—namely, the birth of a child with a severe health condition—to investigate the effect of a life shock on homelessness in large cities in the United States as well as the interactive effects of the shock with housing market characteristics. We considered a traditional measure of homelessness, two measures of housing instability thought to be precursors to homelessness, and a combined measure that approximates the broadened conceptualization of homelessness under the 2009 Homeless Emergency Assistance and Rapid Transition to Housing Act (2010). We found that the shock substantially increases the likelihood of family homelessness, particularly in cities with high housing costs. The findings are consistent with the economic theory of homelessness, which posits that homelessness results from a conjunction of adverse circumstances in which housing markets and individual characteristics collide. PMID:23868747

  2. Physics of Collisionless Shocks Space Plasma Shock Waves

    CERN Document Server

    Balogh, André

    2013-01-01

    The present book provides a contemporary systematic treatment of shock waves in high-temperature collisionless plasmas as are encountered in near Earth space and in Astrophysics. It consists of two parts. Part I develops the complete theory of shocks in dilute hot plasmas under the assumption of absence of collisions among the charged particles when the interaction is mediated solely by the self-consistent electromagnetic fields. Such shocks are naturally magnetised implying that the magnetic field plays an important role in their evolution and dynamics. This part treats both subcritical shocks, which dissipate flow energy by generating anomalous resistance or viscosity, and supercritical shocks. The main emphasis is, however, on super-critical shocks where the anomalous dissipation is insufficient to retard the upstream flow. These shocks, depending on the direction of the upstream magnetic field, are distinguished as quasi-perpendicular and quasi-parallel shocks which exhibit different behaviours, reflecti...

  3. The Shock Routine

    DEFF Research Database (Denmark)

    van Hooren, Franca; Kaasch, Alexandra; Starke, Peter

    2014-01-01

    in Australia, Belgium, the Netherlands and Sweden over the course of four global economic shocks, we ask whether the notion of critical junctures is useful in understanding the nature of change triggered by crisis. The main empirical finding is that fundamental change in the aftermath of an exogenous shock...... is the exception rather than the rule. Instead, incremental ‘crisis routines’ based on existing policy instruments are overwhelmingly used to deal with economic hardship. We discuss these findings in the light of the psychological ‘threat-rigidity’ effect and reflect on their consequences for theories...

  4. Osmotic regulation in leaves and roots of olive trees during a water deficit and rewatering.

    Science.gov (United States)

    Dichio, Bartolomeo; Xiloyannis, Cristos; Sofo, Adriano; Montanaro, Giuseppe

    2006-02-01

    We evaluated the osmotic adjustment capacity of leaves and roots of young olive (Olea europaea L.) trees during a period of water deficit and subsequent rewatering. The trials were carried out in Basilicata (40 degrees 24' N, 16 degrees 48' E) on 2-year-old self-rooted olive plants (cv. 'Coratina'). Plants were subjected to one of four drought treatments. After 13 days of drought, plants reached mean predawn leaf water potentials of -0.45 +/- 0.015 MPa (control), -1.65 +/- 0.021 (low stress), -3.25 +/- 0.035 (medium stress) and -5.35 +/- 0.027 MPa (high stress). Total osmotic adjustment increased with increasing severity of drought stress. Trees in the high stress treatment showed total osmotic adjustments ranging between 2.4 MPa at 0500 h and 3.8 MPa at 1800 h on the last day of the drought period. Osmotic adjustment allowed the leaves to reach leaf water potentials of about -7.0 MPa. Active osmotic adjustment at predawn decreased during the rewatering period in both leaves and roots. Stomatal conductance and net photosynthetic rate declined with increasing drought stress. Osmotic adjustment in olive trees was associated with active and passive osmotic regulation of drought tolerance, providing an important mechanism for avoiding water loss.

  5. Baseline red blood cell osmotic fragility does not predict the degree of post-LVAD hemolysis.

    Science.gov (United States)

    Madden, Jesse L; Drakos, Stavros G; Stehlik, Josef; McKellar, Stephen H; Rondina, Matthew T; Weyrich, Andrew S; Selzman, Craig H

    2014-01-01

    Continuous-flow left ventricular assist devices (LVADs) subject elements of the blood to significant stress, resulting in clinically significant and subclinical hemolysis. We sought to prospectively determine whether baseline red-cell osmotic fragility of an advanced heart-failure patient influences the hemolytic response to LVAD support. Osmotic fragility assesses the degree of red-blood-cell hemolysis under varying degrees of osmotic stress. Assays were prospectively obtained on 50 consecutive patients prior to placement of continuous-flow LVADs: HeartMate II (n = 34), Jarvik 2000 (n = 5), HeartWare (n = 6). The mean age of the patients was 60.2 years and 87% were male and 47% were nonischemic. The overall median post-LVAD lactate dehydrogenase (LDH) was 583 (427-965), and there was no difference between devices. Mean hemolysis was 15.68 ± 12.96% at 0.45% NaCl (the inflection point of the osmotic fragility hemolysis curve). A scatter plot did not reveal any relationship between preoperative osmotic fragility and postoperative LDH. Linear regression confirmed no predictive relationship (p = 0.71). In conclusion, preoperative variations in osmotic fragility do not appear to account for differences in hemolysis following ventricular assist device placement. Mechanical forces generated by existing LVADs result in similar levels of biochemical hemolysis, as assessed by LDH, despite baseline differences in a patient's osmotic red-cell fragility.

  6. The Arabidopsis Vacuolar Sorting Receptor1 Is Required for Osmotic Stress-Induced Abscisic Acid Biosynthesis

    KAUST Repository

    Wang, Zhen-Yu

    2014-11-21

    Osmotic stress activates the biosynthesis of the phytohormone abscisic acid (ABA) through a pathway that is rate limited by the carotenoid cleavage enzyme 9-cis-epoxycarotenoid dioxygenase (NCED). To understand the signal transduction mechanism underlying the activation of ABA biosynthesis, we performed a forward genetic screen to isolate mutants defective in osmotic stress regulation of the NCED3 gene. Here, we identified the Arabidopsis (Arabidopsis thaliana) Vacuolar Sorting Receptor1 (VSR1) as a unique regulator of ABA biosynthesis. The vsr1 mutant not only shows increased sensitivity to osmotic stress, but also is defective in the feedback regulation of ABA biosynthesis by ABA. Further analysis revealed that vacuolar trafficking mediated by VSR1 is required for osmotic stress-responsive ABA biosynthesis and osmotic stress tolerance. Moreover, under osmotic stress conditions, the membrane potential, calcium flux, and vacuolar pH changes in the vsr1 mutant differ from those in the wild type. Given that manipulation of the intracellular pH is sufficient to modulate the expression of ABA biosynthesis genes, including NCED3, and ABA accumulation, we propose that intracellular pH changes caused by osmotic stress may play a signaling role in regulating ABA biosynthesis and that this regulation is dependent on functional VSR1.

  7. A cellulose synthase-like protein is required for osmotic stress tolerance in Arabidopsis

    KAUST Repository

    Zhu, Jianhua

    2010-04-16

    Osmotic stress imposed by soil salinity and drought stress significantly affects plant growth and development, but osmotic stress sensing and tolerance mechanisms are not well understood. Forward genetic screens using a root-bending assay have previously identified salt overly sensitive (sos) mutants of Arabidopsis that fall into five loci, SOS1 to SOS5. These loci are required for the regulation of ion homeostasis or cell expansion under salt stress, but do not play a major role in plant tolerance to the osmotic stress component of soil salinity or drought. Here we report an additional sos mutant, sos6-1, which defines a locus essential for osmotic stress tolerance. sos6-1 plants are hypersensitive to salt stress and osmotic stress imposed by mannitol or polyethylene glycol in culture media or by water deficit in the soil. SOS6 encodes a cellulose synthase-like protein, AtCSLD5. Only modest differences in cell wall chemical composition could be detected, but we found that sos6-1 mutant plants accumulate high levels of reactive oxygen species (ROS) under osmotic stress and are hypersensitive to the oxidative stress reagent methyl viologen. The results suggest that SOS6/AtCSLD5 is not required for normal plant growth and development but has a critical role in osmotic stress tolerance and this function likely involves its regulation of ROS under stress. © 2010 Blackwell Publishing Ltd.

  8. Erythrocyte osmotic fragility of red (Macropus rufus) and grey (Macropus fuliginosus and Macropus giganteus) kangaroos and free-ranging sheep of the arid regions of Australia.

    Science.gov (United States)

    Buffenstein, R; McCarron, H C; Dawson, T J

    2001-02-01

    The mean corpuscular fragility (MCF) of erythrocytes may reflect phylogenetic characteristics as well as an animal's ability to respond to the osmotic challenges associated with cyclic dehydration and rehydration. This type of ecophysiological stress is commonly encountered by animals living in arid regions and low MCF may contribute to their ability to survive and thrive in these xeric habitats. The eastern grey kangaroo has only in recent times extended its range into the arid zone, and is considered a more mesic inhabitant than the red kangaroo. We therefore compared the ability of eastern grey kangaroos and red kangaroos to handle prolonged periods of water restriction, as well as the MCF of the erythrocytes of free-ranging red, eastern grey and western grey kangaroos found at the Fowlers Gap field station. In addition, the MCF of free-ranging sheep inhabiting the same pastures were used as an experimental control; they are phylogenetically unrelated yet are subjected to the same acclimatisation stresses. While red kangaroos exhibited greater tolerance of dehydration compared to eastern grey kangaroos, the MCF of all three kangaroo species was similar and more resilient to osmotic stresses (MCF, 130 mosmol/kg) than erythrocytes of sheep (MCF, 220 mosmol/kg). The MCF did not change with water restriction, however, the erythrocytes of long-term captive populations fed a comparatively better quality diet were more resistant to osmotic shock than the free-ranging animals. Phylogenetic commonality rather than ecophysiological responses to life in the arid zone appeared to influence MCF. The MCF values of sheep corresponded to that of other ovines; similarly the MCF of kangaroos concurred regardless of their preferred habitats. ecological history and differential success in the arid zone.

  9. Gastrointestinal perfusion in septic shock.

    NARCIS (Netherlands)

    Haren, E.M. van; Sleight, J.W.; Pickkers, P.; Hoeven, J.G. van der

    2007-01-01

    Septic shock is characterised by vasodilation, myocardial depression and impaired microcirculatory blood flow, resulting in redistribution of regional blood flow. Animal and human studies have shown that gastrointestinal mucosal blood flow is impaired in septic shock. This is consistent with

  10. Development of hyper osmotic resistant CHO host cells for enhanced antibody production.

    Science.gov (United States)

    Kamachi, Yasuharu; Omasa, Takeshi

    2018-04-01

    Cell culture platform processes are generally employed to shorten the duration of new product development. A fed-batch process with continuous feeding is a conventional platform process for monoclonal antibody production using Chinese hamster ovary (CHO) cells. To establish a simplified platform process, the feeding method can be changed from continuous feed to bolus feed. However, this change induces a rapid increase of osmolality by the bolus addition of nutrients. The increased osmolality suppresses cell culture growth, and the final product concentration is decreased. In this study, osmotic resistant CHO host cells were developed to attain a high product concentration. To establish hyper osmotic resistant CHO host cells, CHO-S host cells were passaged long-term in a hyper osmotic basal medium. There were marked differences in cell growth of the original and established host cells under iso- (328 mOsm/kg) or hyper-osmolality (over 450 mOsm/kg) conditions. Cell growth of the original CHO host cells was markedly decreased by the induction of osmotic stress, whereas cell growth of the hyper osmotic resistant CHO host cells was not affected. The maximum viable cell concentration of hyper osmotic resistant CHO host cells was 132% of CHO-S host cells after the induction of osmotic stress. Moreover, the hyper osmotic resistant characteristic of established CHO host cells was maintained even after seven passages in iso-osmolality basal medium. The use of hyper osmotic resistance CHO host cells to create a monoclonal antibody production cell line might be a new approach to increase final antibody concentrations with a fed-batch process. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  11. Free water transport, small pore transport and the osmotic pressure gradient.

    Science.gov (United States)

    Parikova, Alena; Smit, Watske; Zweers, Machteld M; Struijk, Dirk G; Krediet, Raymond T

    2008-07-01

    Water transport in peritoneal dialysis (PD) patients occurs through the small pores and water channels, the latter allowing free water transport (FWT). The osmotic gradient is known to be one of the major determinants of water transport. The objective of the study was to analyse the relation between each transport route and the osmotic gradient. The 4-h standard peritoneal permeability analyses of 80 stable PD patients were studied. Small pore transport (SPT) was calculated based on the transported amount of sodium. FWT was calculated by subtracting SPT from transcapillary ultrafiltration (TCUF). Water transport rates were determined. The osmotic gradient was calculated. The slope of the relation between FWT rate and osmotic gradient (slope(FWT)), and the elimination constant (K(e)) of the exponential relation between SPT rate and osmotic gradient (K(SPT)) were calculated for every patient. The FWT rate was related to the osmotic gradient (P = 0.001). A similar correlation was also found between the SPT rate and osmotic gradient when fitted exponentially (P = 0.005). The rates of FWT decreased significantly between each time point during the whole dwell. The SPT rates decreased significantly within the first half of the dwell and levelled off thereafter. No correlations were found between the slope(FWT), K(SPT) and PD duration. The slope(FWT) of the relationship between the FWT and the osmotic gradient is an indirect measurement of the amount of functioning water channels. Similarly, the K(SPT) value represents the number of functioning small pores. The absence of a relationship of these parameters with the duration of PD suggests opposing mechanisms, for instance a lower number of functioning pores in combination with an increased vascular surface area. Conclusion. The curves of the relationship between FWR, SPT and OG support the assumption that FWR is much more dependent on the OG than SPT. Non-osmotic determinants are likely to be important in small pore fluid

  12. High relatedness in a social amoeba: the role of kin-discriminatory segregation.

    Science.gov (United States)

    Gilbert, Owen M; Strassmann, Joan E; Queller, David C

    2012-07-07

    A major challenge for social theory is to explain the importance of kin discrimination for the evolution of altruism. One way to assess the importance of kin discrimination is to test its effects on increasing relatedness within groups. The social amoeba Dictyostelium discoideum aggregates to form a fruiting body composed of dead stalk and live spores. Previous studies of a natural population showed that where D. discoideum occurs in the soil, multiple clones are often found in the same small soil samples. However, actual fruiting bodies usually contain only one clone. We here performed experiments to gauge the effect of kin-discriminatory segregation on increasing relatedness. We mixed co-occurring clones from this population using a relatedness level found in small soil samples. We found a lower proportion of uniclonal fruiting bodies and a lower level of relatedness compared with natural fruiting bodies. We found that the amount of relatedness increase attributable to kin-discriminatory segregation was small. These findings suggest a relatively minor influence of kin-discriminatory segregation on relatedness in D. discoideum. We discuss our results comparing with the results of previous studies, including those of wild clones and laboratory mutants. We ask why wild clones of D. discoideum exhibit a low degree of kin-discriminatory segregation, and what alternative factors might account for high relatedness in D. discoideum.

  13. Campylobacter jejuni Actively Invades the Amoeba Acanthamoeba polyphaga and Survives within Non Digestive Vacuoles

    Science.gov (United States)

    Olofsson, Jenny; Axelsson-Olsson, Diana; Brudin, Lars; Olsen, Björn; Ellström, Patrik

    2013-01-01

    The Gram-negative bacterium Campylobacter jejuni is able to enter, survive and multiply within the free living amoeba Acanthamoeba polyphaga, but the molecular mechanisms behind these events are still unclear. We have studied the uptake and intracellular trafficking of viable and heat killed bacterial cells of the C. jejuni strain 81–176 in A. polyphaga. We found that viable bacteria associated with a substantially higher proportion of Acanthamoeba trophozoites than heat killed bacteria. Furthermore, the kinetics of internalization, the total number of internalized bacteria as well as the intracellular localization of internalized C. jejuni were dramatically influenced by bacterial viability. Viable bacteria were internalized at a high rate already after 1 h of co-incubation and were observed in small vacuoles tightly surrounding the bacteria. In contrast, internalization of heat killed C. jejuni was low at early time points and did not peak until 96 h. These cells were gathered in large spacious vacuoles that were part of the degradative pathway as determined by the uptake of fluorescently labeled dextran. The amount of heat killed bacteria internalized by A. polyphaga did never reach the maximal amount of internalized viable bacteria. These results suggest that the uptake and intracellular survival of C. jejuni in A. polyphaga is bacterially induced. PMID:24223169

  14. Free-living amoebae (FLA) co-occurring with legionellae in industrial waters☆

    Science.gov (United States)

    Scheikl, Ute; Sommer, Regina; Kirschner, Alexander; Rameder, Alexandra; Schrammel, Barbara; Zweimüller, Irene; Wesner, Wolfgang; Hinker, Manfred; Walochnik, Julia

    2014-01-01

    Legionella pneumophila is known as the causative agent of Legionnaires’ disease and free-living amoebae (FLA) can serve as vehicles for legionellae. The aim of this study was to screen industrial waters for the occurrence of FLA and their co-occurrence with legionellae. A total of 201 water samples, including 129 cooling waters and 72 process waters, and 30 cooling lubricants were included in the study. Treated waters were screened periodically, pre and post treatment. Altogether, 72.6% of the water samples were positive for FLA, acanthamoebae being most prevalent (in 23.9% of the samples) followed by Vermamoeba vermiformis (19.4%). Only one cooling lubricant was positive (Acanthamoeba genotype T4). Legionella spp. were detected in 34.8% of the water samples and in 15% in high concentrations (>1000 CFU/100 ml). Altogether, 81.4% of the Legionella-positive samples were positive for FLA by standard methods. By applying a highly sensitive nested PCR to a representative set of random samples it was revealed that Legionella spp. always co-occurred with Acanthamoeba spp. Although the addition of disinfectants did influence amoebal density and diversity, treated waters showed no difference concerning FLA in the interphases of disinfection. It appears that FLA can re-colonize treated waters within a short period of time. PMID:25062389

  15. Ophthalmology hospital wards contamination to pathogenic free living Amoebae in Iran.

    Science.gov (United States)

    Lasjerdi, Zohreh; Niyyati, Maryam; Lorenzo-Morales, Jacob; Haghighi, Ali; Taghipour, Niloofar

    2015-09-01

    The present study was conducted to determine the occurrence of potentially pathogenic free-living amoeba in ophthalmology wards in reference hospitals in Iran. Since an increasing number of Acanthamoeba Keratitis cases after eye surgery and eye trauma have been recently observed in this country, it could be possible that the disinfection procedures undertaken in the clinical setting may not have a good hygiene and disinfection procedures, hence the aim of this study. Therefore, 42 dust and biofilm samples were collected from different areas of ophthalmology wards and checked for the presence of FLA using morphological criteria, PCR based analysis and DNA sequencing. Of the 42 samples from dust and biofilm sources, 18(42.86%) isolates were found to contain FLA and 12(92.3%) isolates belonged to Acanthamoeba T4 genotype. Isolation of the pathogenic genotype T4 from medical instruments, including slit lamp in corneal wards, may be a threat for patients undergoing eye surgery in these wards. Other FLA isolated in this study included Acanthamoeba genotype T5, Vahlkampfia sp, Naegleria australiensis, Vermamoeba vermiformis and Echinamoeba exudans. To our knowledge, this is the first report of the presence of potentially pathogenic FLA in ophthalmology wards in Iran. Improved disinfection methods and monitoring of hospitals ward are thus necessary in this area in order to minimize the risk of infection in patients.

  16. Free-living amoebae (FLA) co-occurring with legionellae in industrial waters.

    Science.gov (United States)

    Scheikl, Ute; Sommer, Regina; Kirschner, Alexander; Rameder, Alexandra; Schrammel, Barbara; Zweimüller, Irene; Wesner, Wolfgang; Hinker, Manfred; Walochnik, Julia

    2014-08-01

    Legionella pneumophila is known as the causative agent of Legionnaires' disease and free-living amoebae (FLA) can serve as vehicles for legionellae. The aim of this study was to screen industrial waters for the occurrence of FLA and their co-occurrence with legionellae. A total of 201 water samples, including 129 cooling waters and 72 process waters, and 30 cooling lubricants were included in the study. Treated waters were screened periodically, pre and post treatment. Altogether, 72.6% of the water samples were positive for FLA, acanthamoebae being most prevalent (in 23.9% of the samples) followed by Vermamoeba vermiformis (19.4%). Only one cooling lubricant was positive (Acanthamoeba genotype T4). Legionella spp. were detected in 34.8% of the water samples and in 15% in high concentrations (>1000 CFU/100 ml). Altogether, 81.4% of the Legionella-positive samples were positive for FLA by standard methods. By applying a highly sensitive nested PCR to a representative set of random samples it was revealed that Legionella spp. always co-occurred with Acanthamoeba spp. Although the addition of disinfectants did influence amoebal density and diversity, treated waters showed no difference concerning FLA in the interphases of disinfection. It appears that FLA can re-colonize treated waters within a short period of time. Copyright © 2014 The Authors. Published by Elsevier GmbH.. All rights reserved.

  17. Planktonic free-living amoebae susceptibility to dental unit waterlines disinfectants.

    Science.gov (United States)

    Costa, Damien; Bossard, Valentin; Brunet, Kévin; Fradin, Benjamin; Imbert, Christine

    2017-11-30

    A high diversity of microorganisms is encountered inside dental unit waterlines (DUWL). Among those the presence of free-living amoebae (FLA) appears currently underestimated, although human infections may occur due to contact with FLA-contaminated water during dental cares. In order to limit microbial DUWL contamination, disinfectants are provided by dental unit manufacturer, however, with limited documentation on their activities against FLA. The aim of this study was to evaluate the efficiency of three commercial DUWL disinfectants: the Calbenium© (Airel, Champigny-sur-Marne, France), the Oxygenal 6© (Kavo, Biberach, Germany) and the Sterispray© (Gammasonic, Billom, France), against two FLA species, i.e. Acanthamoeba castellanii and Vermamoeba vermiformis alone or co-cultured with Pseudomonas aeruginosa and Candida albicans at concentrations ranging from 0% to 5% (v/v). Results showed varied efficacies of disinfectants: the Oxygenal 6© did not exhibit FLA killing activity, while the Sterispray© and the Calbenium© displayed concentration- and species-dependent activities with a maximum eradication rates of 100% and 86%, and 79% and 97% for A. castellani and V. vermiformis, respectively. None of the disinfectants were able to totally eradicate FLA at concentrations recommended by manufacturers. Present results highlight unsatisfactory anti-FLA activities of 3 DUWL disinfectant preparations advocating deeper investigation of antimicrobial spectra of commercial disinfectants in use for DUWL maintenance. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Lateral gene exchanges shape the genomes of amoeba-resisting microorganisms

    Directory of Open Access Journals (Sweden)

    Claire eBertelli

    2012-08-01

    Full Text Available Based on Darwin’s concept of the tree of life, vertical inheritance was thought to be dominant, and mutations, deletions and duplication were streaming the genomes of living organisms. In the current genomic era, increasing data indicated that both vertical and lateral gene inheritance interact in space and time to trigger genome evolution, particularly among microorganisms sharing a given ecological niche. As a paradigm to their diversity and their survival in a variety of cell types, intracellular microorganisms, and notably intracellular bacteria, were considered as less prone to lateral genetic exchanges. Such specialized microorganisms generally have a smaller gene repertoire because they do rely on their host’s factors for some basic regulatory and metabolic functions. Here we review events of lateral gene transfer (LGT that illustrate the genetic exchanges among intra-amoebal microorganisms or between the microorganism and its amoebal host. We tentatively investigate the functions of laterally transferred genes in the light of the interaction with their host as they should confer a selective advantage and success to the amoeba-resisting microorganisms.

  19. Comparative recoveries of Naegleria fowleri amoebae from seeded river water by filtration and centrifugation.

    Science.gov (United States)

    Pernin, P; Pélandakis, M; Rouby, Y; Faure, A; Siclet, F

    1998-03-01

    Detection of pathogenic Naegleria fowleri in environmental water samples, which is necessary for the prevention of primary amoebic meningoencephalitis, generally requires concentrating the samples. Two concentration techniques, filtration and centrifugation, were used to study the recovery of N. fowleri, in vegetative or cystic form, that had been mixed with the two other thermotolerant Naegleria species, N. lovaniensis and N. australiensis. Counting of amoebae was performed by the most probable number method on 10 water replicates of 100 ml and 10 ml each. With both concentration methods, recovery was better for cysts than for trophozoites (53% +/- 21% versus 5% +/- 5% by filtration and 57% +/- 25% versus 22% +/- 5% by centrifugation). The recovery of Naegleria trophozoites by filtration was very low, and centrifugation was significantly better than filtration in recovery of Naegleria trophozoites (22% +/- 5% versus 5% +/- 5%; P 0.7). Although the recovery of cysts of N. fowleri obtained by filtration (51% +/- 24%) appeared higher than that by centrifugation (36% +/- 23%), the difference was not significant (P > 0.1). Both concentration methods have highly variable recovery rates, making accurate quantification of low concentrations (< 100/liter) of N. fowleri in the environment difficult.

  20. Amoebae, Giant Viruses, and Virophages Make Up a Complex, Multilayered Threesome.

    Science.gov (United States)

    Diesend, Jan; Kruse, Janis; Hagedorn, Monica; Hammann, Christian

    2017-01-01

    Viral infection had not been observed for amoebae, until the Acanthamoeba polyphaga mimivirus (APMV) was discovered in 2003. APMV belongs to the nucleocytoplasmatic large DNA virus (NCLDV) family and infects not only A. polyphaga , but also other professional phagocytes. Here, we review the Megavirales to give an overview of the current members of the Mimi - and Marseilleviridae families and their structural features during amoebal infection. We summarize the different steps of their infection cycle in A. polyphaga and Acanthamoeba castellani . Furthermore, we dive into the emerging field of virophages, which parasitize upon viral factories of the Megavirales family. The discovery of virophages in 2008 and research in recent years revealed an increasingly complex network of interactions between cell, giant virus, and virophage. Virophages seem to be highly abundant in the environment and occupy the same niches as the Mimiviridae and their hosts. Establishment of metagenomic and co-culture approaches rapidly increased the number of detected virophages over the recent years. Genetic interaction of cell and virophage might constitute a potent defense machinery against giant viruses and seems to be important for survival of the infected cell during mimivirus infections. Nonetheless, the molecular events during co-infection and the interactions of cell, giant virus, and virophage have not been elucidated, yet. However, the genetic interactions of these three, suggest an intricate, multilayered network during amoebal (co-)infections. Understanding these interactions could elucidate molecular events essential for proper viral factory activity and could implicate new ways of treating viruses that form viral factories.

  1. Comparative Recoveries of Naegleria fowleri Amoebae from Seeded River Water by Filtration and Centrifugation

    Science.gov (United States)

    Pernin, P.; Pélandakis, M.; Rouby, Y.; Faure, A.; Siclet, F.

    1998-01-01

    Detection of pathogenic Naegleria fowleri in environmental water samples, which is necessary for the prevention of primary amoebic meningoencephalitis, generally requires concentrating the samples. Two concentration techniques, filtration and centrifugation, were used to study the recovery of N. fowleri, in vegetative or cystic form, that had been mixed with the two other thermotolerant Naegleria species, N. lovaniensis and N. australiensis. Counting of amoebae was performed by the most probable number method on 10 water replicates of 100 ml and 10 ml each. With both concentration methods, recovery was better for cysts than for trophozoites (53% ± 21% versus 5% ± 5% by filtration and 57% ± 25% versus 22% ± 5% by centrifugation). The recovery of Naegleria trophozoites by filtration was very low, and centrifugation was significantly better than filtration in recovery of Naegleria trophozoites (22% ± 5% versus 5% ± 5%; P 0.7). Although the recovery of cysts of N. fowleri obtained by filtration (51% ± 24%) appeared higher than that by centrifugation (36% ± 23%), the difference was not significant (P > 0.1). Both concentration methods have highly variable recovery rates, making accurate quantification of low concentrations (fowleri in the environment difficult. PMID:9501435

  2. Quadrulella texcalense sp. nov. from a Mexican desert: An unexpected new environment for hyalospheniid testate amoebae.

    Science.gov (United States)

    Pérez-Juárez, Horacio; Serrano-Vázquez, Angélica; Kosakyan, Anush; Mitchell, Edward A D; Rivera Aguilar, Víctor M; Lahr, Daniel J G; Hernández Moreno, Mayra M; Cuellar, Humberto Macías; Eguiarte, Luis E; Lara, Enrique

    2017-10-01

    Quadrulella (Amoebozoa, Arcellinida, Hyalospheniidae) is a genus of testate amoebae with unmistakable morphology, which secretes characteristic square plates to reinforce the test. They are mainly known from fens and freshwater habitats and have never been documented in deserts. We describe a new species, Quadrulella texcalense, from biological soil crusts in the intertropical desert of Tehuacán (state of Puebla, Mexico). Quadrulella texcalense occurred only at altitudes between 2140 and 2221m.a.s.l., together with the bryophyte genera Pseudocrossidium, Weissia, Bryum, Didymodon, Neohyophyla and Aloina. The soil was extremely dry (moisture of 1.97-2.6%), which contrasts sharply with previous reports for the Quadrulella genus. Single cell mitochondrial cytochrome oxidase I (COI) barcoding of thirteen isolated cells showed an important morphological variability despite having all the same COI barcode sequence. Quadrulella texcalense was placed in a tree containing other Hyalsopheniidae, including a newly barcoded South African species, Q. elegans. Q. texcalense unambiguously branched within genus Quadrulella in a compact clade but with a long branch, suggesting accelerated evolution due to a transition towards a new environment and/or under-sampling. Copyright © 2017 Elsevier GmbH. All rights reserved.

  3. Extracellular matrix dynamics and functions in the social amoeba Dictyostelium: A critical review.

    Science.gov (United States)

    Huber, Robert J; O'Day, Danton H

    2017-01-01

    The extracellular matrix (ECM) is a dynamic complex of glycoproteins, proteoglycans, carbohydrates, and collagen that serves as an interface between mammalian cells and their extracellular environment. Essential for normal cellular homeostasis, physiology, and events that occur during development, it is also a key functionary in a number of human diseases including cancer. The social amoeba Dictyostelium discoideum secretes an ECM during multicellular development that regulates multicellularity, cell motility, cell differentiation, and morphogenesis, and provides structural support and protective layers to the resulting differentiated cell types. Proteolytic processing within the Dictyostelium ECM leads to specific bioactive factors that regulate cell motility and differentiation. Here we review the structure and functions of the Dictyostelium ECM and its role in regulating multicellular development. The questions and challenges that remain and how they can be answered are also discussed. The Dictyostelium ECM shares many of the features of mammalian and plant ECM, and thus presents an excellent system for studying the structure and function of the ECM. As a genetically tractable model organism, Dictyostelium offers the potential to further elucidate ECM functions, and to possibly reveal previously unknown roles for the ECM. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Campylobacter jejuni actively invades the amoeba Acanthamoeba polyphaga and survives within non digestive vacuoles.

    Directory of Open Access Journals (Sweden)

    Jenny Olofsson

    Full Text Available The Gram-negative bacterium Campylobacter jejuni is able to enter, survive and multiply within the free living amoeba Acanthamoeba polyphaga, but the molecular mechanisms behind these events are still unclear. We have studied the uptake and intracellular trafficking of viable and heat killed bacterial cells of the C. jejuni strain 81-176 in A. polyphaga. We found that viable bacteria associated with a substantially higher proportion of Acanthamoeba trophozoites than heat killed bacteria. Furthermore, the kinetics of internalization, the total number of internalized bacteria as well as the intracellular localization of internalized C. jejuni were dramatically influenced by bacterial viability. Viable bacteria were internalized at a high rate already after 1 h of co-incubation and were observed in small vacuoles tightly surrounding the bacteria. In contrast, internalization of heat killed C. jejuni was low at early time points and did not peak until 96 h. These cells were gathered in large spacious vacuoles that were part of the degradative pathway as determined by the uptake of fluorescently labeled dextran. The amount of heat killed bacteria internalized by A. polyphaga did never reach the maximal amount of internalized viable bacteria. These results suggest that the uptake and intracellular survival of C. jejuni in A. polyphaga is bacterially induced.

  5. Isolation and Identification of Free-Living Amoebae from Tap Water in Sivas, Turkey

    Directory of Open Access Journals (Sweden)

    Kübra Açıkalın Coşkun

    2013-01-01

    Full Text Available The present work focuses on a local survey of free-living amoebae (FLA that cause opportunistic and nonopportunistic infections in humans. Determining the prevalence of FLA in water sources can shine a light on the need to prevent FLA related illnesses. A total of 150 samples of tap water were collected from six districts of Sivas province. The samples were filtered and seeded on nonnutrient agar containing Escherichia coli spread. Thirty-three (22% out of 150 samples were found to be positive for FLA. The FLA were identified by morphology and by PCR using 18S rDNA gene. The morphological analysis and partial sequencing of the 18S rDNA gene revealed the presence of three different species, Acanthamoeba castellanii, Acanthamoeba polyphaga, and Hartmannella vermiformis. Naegleria fowleri, Balamuthia mandrillaris, or Sappinia sp. was not isolated during the study. All A. castellanii and A. polyphaga sequence types were found to be genotype T4 that contains most of the pathogenic Acanthamoeba strains. The results indicated the occurrence and distribution of FLA species in tap water in these localities of Sivas, Turkey. Furthermore, the presence of temperature tolerant Acanthamoeba genotype T4 in tap water in the region must be taken into account for health risks.

  6. Influence of climate and geography on the occurrence of Legionella and amoebae in composting facilities.

    Science.gov (United States)

    Conza, Lisa; Casati Pagani, Simona; Gaia, Valeria

    2014-11-24

    The incidence of Legionnaires' disease (LD) in southern Switzerland is three times higher than in northern Switzerland. Climatic and geographic factors may be potential causes for this difference.We studied the prevalence of Legionella and free-living amoebae (FLA) in compost and bioaerosol in two Swiss regions to understand the role of climate and geography in the transmission of LD. We also tried to investigate whether or not compost storage duration would influence the composition of Legionella and FLA communities. A larger proportion of compost heaps in facilities from southern Switzerland harbor more diverse Legionella compared to the north (P=0.0146). FLA were isolated from composts in northern facilities at slightly higher rates (88.2% vs. 69.2%) and at lower rates from bioaerosols (6.3% vs. 13%) than in southern Switzerland. The diversity of FLA was higher in northern than in southern Switzerland (80% vs. 65%). A general decrease in the presence and variety of species was observed with decreasing compost storage time length. A discriminant model showed that values of vapour pressure, relative humidity and temperature distinguish the two regions, which were also characterised by different contamination rates by FLA and Legionella. The duration of outdoor storage may favour contamination of the compost by Legionella, and may increase the number and isolation of Legionella naturally occurring in compost. The climate in the south seems to favour higher Legionella contamination of compost heaps: this could explain the higher incidence of LD in southern Switzerland.

  7. Pediatric cardiogenic shock: Current perspectives

    OpenAIRE

    Subhranshu Sekhar Kar

    2015-01-01

    Cardiogenic shock is a pathophysiologic state where an abnormality of cardiac function is responsible for the failure of the cardiovascular system to meet the metabolic needs of the body tissues.Though it is less common than hypovolemia as the primary etiology in paediatric shock, eventually myocardial function is affected because of reduced perfusion in all forms of shock. Myocardial malfunction, in other forms of shock, is secondary to ischemia, acidosis, drugs, toxins or inflammation. Card...

  8. Teleconnected food supply shocks

    Science.gov (United States)

    Bren d'Amour, Christopher; Wenz, Leonie; Kalkuhl, Matthias; Steckel, Jan Christoph; Creutzig, Felix

    2016-03-01

    The 2008-2010 food crisis might have been a harbinger of fundamental climate-induced food crises with geopolitical implications. Heat-wave-induced yield losses in Russia and resulting export restrictions led to increases in market prices for wheat across the Middle East, likely contributing to the Arab Spring. With ongoing climate change, temperatures and temperature variability will rise, leading to higher uncertainty in yields for major nutritional crops. Here we investigate which countries are most vulnerable to teleconnected supply-shocks, i.e. where diets strongly rely on the import of wheat, maize, or rice, and where a large share of the population is living in poverty. We find that the Middle East is most sensitive to teleconnected supply shocks in wheat, Central America to supply shocks in maize, and Western Africa to supply shocks in rice. Weighing with poverty levels, Sub-Saharan Africa is most affected. Altogether, a simultaneous 10% reduction in exports of wheat, rice, and maize would reduce caloric intake of 55 million people living in poverty by about 5%. Export bans in major producing regions would put up to 200 million people below the poverty line at risk, 90% of which live in Sub-Saharan Africa. Our results suggest that a region-specific combination of national increases in agricultural productivity and diversification of trade partners and diets can effectively decrease future food security risks.

  9. SHOCK-INDUCED LUMINESCENCE

    Science.gov (United States)

    When a 270 kilobar shock wave emerges from an illuminated aluminum surface in a vacuum, blue light is emitted. This phenomenon is affected...acoustoelectric effect). The electrons reach the aluminum oxide layer and, falling into the ionized F’ centers, emit blue light .

  10. Health Shocks and Retirement:

    DEFF Research Database (Denmark)

    Datta Gupta, Nabanita; Larsen, Mona

    benefits in Denmark nor by the promotion of corporate social responsibility initiatives since the mid-1990s. In the late 1990s, however, the retirement rate following a health shock is reduced to 3% with the introduction of the subsidized employment program (fleksjob) but this effect is not strongly...

  11. Shock tube Multiphase Experiments

    Science.gov (United States)

    Middlebrooks, John; Allen, Roy; Paudel, Manoj; Young, Calvin; Musick, Ben; McFarland, Jacob

    2017-11-01

    Shock driven multiphase instabilities (SDMI) are unique physical phenomena that have far-reaching practical applications in engineering and science. The instability is present in high energy explosions, scramjet combustors, and supernovae events. The SDMI arises when a multiphase interface is impulsively accelerated by the passage of a shockwave. It is similar in development to the Richtmyer-Meshkov (RM) instability however, particle-to-gas coupling is the driving mechanism of the SDMI. As particle effects such as lag and phase change become more prominent, the SDMI's development begins to significantly deviate from the RM instability. We have developed an experiment for studying the SDMI in our shock tube facility. In our experiments, a multiphase interface is created using a laminar jet and flowed into the shock tube where it is accelerated by the passage of a planar shockwave. The interface development is captured using CCD cameras synchronized with planar laser illumination. This talk will give an overview of new experiments conducted to examine the development of a shocked cylindrical multiphase interface. The effects of Atwood number, particle size, and a second acceleration (reshock) of the interface will be discussed.

  12. Osmotic coefficients of water for thorium nitrate solutions at 25, 37, and 50oC

    International Nuclear Information System (INIS)

    Lemire, R.J.; Sagert, N.H.; Lau, D.W.P.

    1983-01-01

    Vapor pressure osmometry was used to measure osmotic coefficients of water for thorium nitrate solutions at 25, 37, and 50 o C and at molalities up to 0.2 mol·kg -1 . The data were fitted to three- and four-parameter equations containing limiting-law terms for a 4:1 electrolyte. The variation of the osmotic coefficients as a function of temperature was found to be small. The results are compared to published values for the osmotic coefficients. (author)

  13. Renal blood flow, early distal sodium, and plasma renin concentrations during osmotic diuresis

    DEFF Research Database (Denmark)

    Leyssac, P P; Holstein-Rathlou, N H; Skøtt, O

    2000-01-01

    Inconsistencies in previous reports regarding changes in early distal NaCl concentration (ED(NaCl)) and renin secretion during osmotic diuresis motivated our reinvestigation. After intravenous infusion of 10% mannitol, ED(NaCl) fell from 42.6 to 34.2 mM. Proximal tubular pressure increased by 12....... There was a significant inverse relationship between superficial nephron ED(NaCl) and PRC. We conclude that ED(Na) decreases during osmotic diuresis, suggesting that the increase in PRC was mediated by the macula densa. The results suggest that the natriuresis during osmotic diuresis is a result of impaired sodium...

  14. STEREO interplanetary shocks and foreshocks

    Energy Technology Data Exchange (ETDEWEB)

    Blanco-Cano, X. [Instituto de Geofisica, UNAM, CU, Coyoacan 04510 DF (Mexico); Kajdic, P. [IRAP-University of Toulouse, CNRS, Toulouse (France); Aguilar-Rodriguez, E. [Instituto de Geofisica, UNAM, Morelia (Mexico); Russell, C. T. [ESS and IGPP, University of California, Los Angeles, 603 Charles Young Drive, Los Angeles, CA 90095 (United States); Jian, L. K. [NASA Goddard Space Flight Center, Greenbelt, MD and University of Maryland, College Park, MD (United States); Luhmann, J. G. [SSL, University of California Berkeley (United States)

    2013-06-13

    We use STEREO data to study shocks driven by stream interactions and the waves associated with them. During the years of the extended solar minimum 2007-2010, stream interaction shocks have Mach numbers between 1.1-3.8 and {theta}{sub Bn}{approx}20-86 Degree-Sign . We find a variety of waves, including whistlers and low frequency fluctuations. Upstream whistler waves may be generated at the shock and upstream ultra low frequency (ULF) waves can be driven locally by ion instabilities. The downstream wave spectra can be formed by both, locally generated perturbations, and shock transmitted waves. We find that many quasiperpendicular shocks can be accompanied by ULF wave and ion foreshocks, which is in contrast to Earth's bow shock. Fluctuations downstream of quasi-parallel shocks tend to have larger amplitudes than waves downstream of quasi-perpendicular shocks. Proton foreshocks of shocks driven by stream interactions have extensions dr {<=}0.05 AU. This is smaller than foreshock extensions for ICME driven shocks. The difference in foreshock extensions is related to the fact that ICME driven shocks are formed closer to the Sun and therefore begin to accelerate particles very early in their existence, while stream interaction shocks form at {approx}1 AU and have been producing suprathermal particles for a shorter time.

  15. Shock Waves in Gas Dynamics

    Directory of Open Access Journals (Sweden)

    Abdolrahman Razani

    2007-11-01

    Full Text Available Shock wave theory was studied in literature by many authors. This article presents a survey with references about various topics related to shock waves: Hyperbolic conservation laws, Well-posedness theory, Compactness theory, Shock and reaction-diffusion wave, The CJ and ZND theory, Existence of detonation in Majda's model, Premixed laminar flame, Multidimensional gas flows, Multidimensional Riemann problem.

  16. Shock wave treatment in medicine

    Indian Academy of Sciences (India)

    Urology has long been the only medical field for shock waves in medicine. Meanwhile shock waves have been used in orthopedics and traumatology to treat insertion tendinitis, avascular necrosis of the head of femur and other necrotic bone alterations. Another field of shock wave application is the treatment of tendons, ...

  17. Fascinating World of Shock Waves

    Indian Academy of Sciences (India)

    Srimath

    travelling at supersonic speeds (more than the sound speed at local temperature) then one can see a shock wave around the body as shown in Figure 1. Dissipation of energy, rapid changes in velocity, presure, temperature and flow turning are some of the features associated with shock waves. Obviously the word 'shock.

  18. Shock wave treatment in medicine

    Indian Academy of Sciences (India)

    Unknown

    compared to urology where shock waves are used for disintegration. [Shrivastava S K and Kailash 2005 Shock wave treatment in medicine; J. Biosci. 30 269–275]. 1. Introduction. Extracorporeal generated shock waves have been intro- duced for medical therapy approximately 20 years back to disintegrate kidney stones.

  19. The rate of hypo-osmotic challenge influences regulatory volume decrease (RVD) and mechanical properties of articular chondrocytes.

    Science.gov (United States)

    Wang, Z; Irianto, J; Kazun, S; Wang, W; Knight, M M

    2015-02-01

    Osteoarthritis (OA) is associated with a gradual reduction in the interstitial osmotic pressure within articular cartilage. The aim of this study was to compare the effects of sudden and gradual hypo-osmotic challenge on chondrocyte morphology and biomechanics. Bovine articular chondrocytes were exposed to a reduction in extracellular osmolality from 327 to 153 mOsmol/kg applied either suddenly (osmotic stress, 66% of chondrocytes exhibited an increase in diameter followed by RVD, whilst 25% showed no RVD. By contrast, cells exposed to gradual hypo-osmotic stress exhibited reduced cell swelling without subsequent RVD. There was an increase in the equilibrium modulus for cells exposed to sudden hypo-osmotic stress. However, gradual hypo-osmotic challenge had no effect on cell mechanical properties. This cell stiffening response to sudden hypo-osmotic challenge was abolished when actin organization was disrupted with cytochalasin D or RVD inhibited with REV5901. Both sudden and gradual hypo-osmotic challenge reduced cortical F-actin distribution and caused chromatin decondensation. Sudden hypo-osmotic challenge increases chondrocyte mechanics by activation of RVD and interaction with the actin cytoskeleton. Moreover, the rate of hypo-osmotic challenge is shown to have a profound effect on chondrocyte morphology and biomechanics. This important phenomenon needs to be considered when studying the response of chondrocytes to pathological hypo-osmotic stress. Copyright © 2014 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

  20. Shock Dynamics in Stellar Outbursts. I. Shock Formation

    Energy Technology Data Exchange (ETDEWEB)

    Ro, Stephen; Matzner, Christopher D., E-mail: ro@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada)

    2017-05-20

    Wave-driven outflows and non-disruptive explosions have been implicated in pre-supernova outbursts, supernova impostors, luminous blue variable eruptions, and some narrow-line and superluminous supernovae. To model these events, we investigate the dynamics of stars set in motion by strong acoustic pulses and wave trains, focusing on nonlinear wave propagation, shock formation, and an early phase of the development of a weak shock. We identify the shock formation radius, showing that a heuristic estimate based on crossing characteristics matches an exact expansion around the wave front and verifying both with numerical experiments. Our general analytical condition for shock formation applies to one-dimensional motions within any static environment, including both eruptions and implosions. We also consider the early phase of shock energy dissipation. We find that waves of super-Eddington acoustic luminosity always create shocks, rather than damping by radiative diffusion. Therefore, shock formation is integral to super-Eddington outbursts.

  1. Errors when shock waves interact due to numerical shock width

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, R.

    1993-03-04

    A simple test problem proposed by Noh, a strong shock reflecting from a rigid wall, demonstrates a generic problem with numerical shock capturing algorithms at boundaries that Noh called ``excess wall heating.`` We show that the same type of numerical error occurs in general when shock waves interact. The underlying cause is the non-uniform convergence to the hyperbolic solution of the inviscid limit of the solution to the PDEs with viscosity. The error can be understood from an analysis of the asymptotic solution. For a propagating shock, there is a difference in the total energy of the parabolic wave relative to the hyperbolic shock. Moreover, the relative energy depends on the strength of the shock. The error when shock waves interact is due to the difference in the relative energies between the incoming and outgoing shock waves. It is analogous to a phase shift in a scattering matrix. A conservative differencing scheme correctly describes the Hugoniot jump conditions for a steady propagating shock. Therefore, the error from the asymptotics occurs in the transient when the waves interact. The entropy error that occurs in the interaction region remains localized but does not dissipate. A scaling argument shows that as the viscosity coefficient goes to zero, the error shrinks in spatial extend but is constant in magnitude. Noh`s problem of the reflection of a shock from a rigid wall is equivalent to the symmetric impact of two shock waves of the opposite family. The asymptotic argument shows that the same type of numerical error would occur when the shocks are of unequal strength. Thus, Noh`s problem is indicative of a numerical error that occurs when shocks interact due to the numerical shock width.

  2. Errors when shock waves interact due to numerical shock width

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, R.

    1993-03-04

    A simple test problem proposed by Noh, a strong shock reflecting from a rigid wall, demonstrates a generic problem with numerical shock capturing algorithms at boundaries that Noh called excess wall heating.'' We show that the same type of numerical error occurs in general when shock waves interact. The underlying cause is the non-uniform convergence to the hyperbolic solution of the inviscid limit of the solution to the PDEs with viscosity. The error can be understood from an analysis of the asymptotic solution. For a propagating shock, there is a difference in the total energy of the parabolic wave relative to the hyperbolic shock. Moreover, the relative energy depends on the strength of the shock. The error when shock waves interact is due to the difference in the relative energies between the incoming and outgoing shock waves. It is analogous to a phase shift in a scattering matrix. A conservative differencing scheme correctly describes the Hugoniot jump conditions for a steady propagating shock. Therefore, the error from the asymptotics occurs in the transient when the waves interact. The entropy error that occurs in the interaction region remains localized but does not dissipate. A scaling argument shows that as the viscosity coefficient goes to zero, the error shrinks in spatial extend but is constant in magnitude. Noh's problem of the reflection of a shock from a rigid wall is equivalent to the symmetric impact of two shock waves of the opposite family. The asymptotic argument shows that the same type of numerical error would occur when the shocks are of unequal strength. Thus, Noh's problem is indicative of a numerical error that occurs when shocks interact due to the numerical shock width.

  3. Flourish or flush: effects of simulated extreme rainfall events on Sphagnum-dwelling testate amoebae in a subarctic bog (Abisko, Sweden).

    Science.gov (United States)

    Tsyganov, Andrey N; Keuper, Frida; Aerts, Rien; Beyens, Louis

    2013-01-01

    Extreme precipitation events are recognised as important drivers of ecosystem responses to climate change and can considerably affect high-latitude ombrotrophic bogs. Therefore, understanding the relationships between increased rainfall and the biotic components of these ecosystems is necessary for an estimation of climate change impacts. We studied overall effects of increased magnitude, intensity and frequency of rainfall on assemblages of Sphagnum-dwelling testate amoebae in a field climate manipulation experiment located in a relatively dry subarctic bog (Abisko, Sweden). The effects of the treatment were estimated using abundance, species diversity and structure of living and empty shell assemblages of testate amoebae in living and decaying layers of Sphagnum. Our results show that increased rainfall reduced the mean abundance and species richness of living testate amoebae. Besides, the treatment affected species structure of both living and empty shell assemblages, reducing proportions of hydrophilous species. The effects are counterintuitive as increased precipitation-related substrate moisture was expected to have opposite effects on testate amoeba assemblages in relatively dry biotopes. Therefore, we conclude that other rainfall-related factors such as increased infiltration rates and frequency of environmental disturbances can also affect testate amoeba assemblages in Sphagnum and that hydrophilous species are particularly sensitive to variation in these environmental variables.

  4. Effect of thermal additions on the density and distribution of thermophilic amoebae and pathogenic Naegleria fowleri in a newly created cooling lake

    Energy Technology Data Exchange (ETDEWEB)

    Tyndall, R.L.; Ironside, K.S.; Metler, P.L.; Tan, E.L. (Univ. of Tennessee, Knoxville (USA)); Hazen, T.C.; Fliermans, C.B. (E.I. du Pont de Nemours and Co., Inc., Aiken, SC (USA))

    1989-03-01

    Pathogenic Naegleria fowleri is the causative agent of fatal human amoebic meningoencephalitis. The protozoan is ubiquitous in nature, and its presence is enhanced by thermal additions. In this investigation, water and sediments from a newly created cooling lake were quantitatively analyzed for the presence of thermophilic amoebae, thermophilic Naegleria spp., and the pathogen Naegleria fowleri. During periods of thermal additions, the concentrations of thermophilic amoebae and thermophilic Naegleria spp. increased as much as 5 orders of magnitude, and the concentration of the pathogen N. fowleri increased as much as 2 orders of magnitude. Concentrations of amoebae returned to prior thermal perturbation levels within 30 to 60 days after cessation of thermal additions. Increases in the thermophilic amoeba concentrations were noted in Savannah River oxbows downriver from the Savannah River plant discharge streams as compared with oxbows upriver from the discharges. Concentrations of thermophilic amoebae and thermophilic Naegleria spp. correlated significantly with temperature and conductivity. Air samples taken proximal to the lade during periods of thermal addition showed no evidence of thermophilic Naegleria spp. Isoenzyme patterns of the N. fowleri isolated from the cooling lake were identical to patterns of N. fowleri isolated from other sites in the United States and Belgium.

  5. Shock detachment from curved wedges

    Science.gov (United States)

    Mölder, S.

    2017-09-01

    Curved shock theory is used to show that the flow behind attached shocks on doubly curved wedges can have either positive or negative post-shock pressure gradients depending on the freestream Mach number, the wedge angle and the two wedge curvatures. Given enough wedge length, the flow near the leading edge can choke to force the shock to detach from the wedge. This local choking can preempt both the maximum deflection and the sonic criteria for shock detachment. Analytical predictions for detachment by local choking are supported by CFD results.

  6. Osmotically unresponsive water fraction on proteins: non-ideal osmotic pressure of bovine serum albumin as a function of pH and salt concentration.

    Science.gov (United States)

    Fullerton, Gary D; Kanal, Kalpana M; Cameron, Ivan L

    2006-01-01

    How much does protein-associated water differ in colligative properties (freezing point, boiling point, vapor pressure and osmotic behavior) from pure bulk water? This question was approached by studying the globular protein bovine serum albumin (BSA), using changes in pH and salt concentration to alter its native structural conformation and state of aggregation. BSA osmotic pressure was investigated experimentally and analyzed using the molecular model of Fullerton et al. [Biochem Cell Biol 1992;70(12):1325]. Analysis yielded both the extent of osmotically unresponsive water (OUW) and the effective molecular weight values of the membrane-impermeable BSA solute. Manipulation of BSA conformation and aggregation by membrane-penetrating cosolutes show that alterations in pH and salt concentration change the amount of bulk water that escapes into BSA from a minimum of 1.4 to a maximum of 11.7 g water per g dry mass BSA.

  7. Electro-Osmotic Pulse (EOP) Technology for Control of Water Seepage in Concrete Structures

    National Research Council Canada - National Science Library

    McInerney, Michael

    2002-01-01

    ..."). A commercial system that uses electro-osmotic pulse (EOP) technology within concrete structures offers an alternative to the trench-and-drain approach that can mitigate water-related problems from the interior (negative side...

  8. Long-term mannitol-induced osmotic stress leads to stomatal ...

    African Journals Online (AJOL)

    Long-term mannitol-induced osmotic stress leads to stomatal closure, carbohydrate accumulation and changes in leaf elasticity in Phaselous vulgaris leaves. S Sassi, S Aydi, K Hessini, EM Gonzalez, C Arrese-Igor, C Abdelly ...

  9. Red blood cell phosphate concentration and osmotic resistance during dietary phosphate depletion in dairy cows

    NARCIS (Netherlands)

    Grünberg, W; Mol, J A; Teske, E

    BACKGROUND: Hypophosphatemia in early lactating dairy cows has been implicated as primary cause for postparturient hemoglobinuria in cattle. Decreased availability of phosphorus has been proposed to reduce adenosine triphosphate synthesis of erythrocytes and thereby reduce osmotic resistance of

  10. Clinical semiology and neuroradiologic correlates of acute hypernatremic osmotic challenge in adults: a literature review.

    Science.gov (United States)

    Ismail, F Y; Szóllics, A; Szólics, M; Nagelkerke, N; Ljubisavljevic, M

    2013-12-01

    The complex interplay between hypernatremic osmotic disturbances and cerebral lesions is yet to be clarified. In this review, we discuss, on the basis of the reported data of hypernatremic CNS challenge in the adult population, the clinical and radiologic features of the condition. Our search captured 20 case studies and 1 case series with 30 patients in total who acquired acute hypernatremia due to different etiologies and developed CNS lesions. We explored the associations between premorbid conditions, clinical presentation, hypernatremic state, correction rate, and radiologic appearance, including the localization of brain lesions and the outcomes. The results revealed that altered mental status was the most commonly reported symptom and osmotic demyelination syndrome in the form of extrapontine myelinolysis was the prevailing radiologic pattern. Finally, we contrasted, when appropriate, clinical and experimental data related to hypernatremic and hyponatremic osmotic insults to aid the understanding of the pathophysiology of CNS osmotic brain injury.

  11. On equations for the total suction and its matric and osmotic components

    International Nuclear Information System (INIS)

    Dao, Vinh N.T.; Morris, Peter H.; Dux, Peter F.

    2008-01-01

    A clear fundamental understanding of suctions is crucial for the study of the behaviour of plastic cement mortar and concrete, including plastic shrinkage cracking. In this paper, the expression relating the change in free energy of the pore water with an isothermal change in pressure is first derived. Based upon definitions of suctions, it is then shown that total, matric, and osmotic suctions can all be expressed in the same thermodynamic form. The widely accepted, but not yet satisfactorily validated, assumption that the total suction comprises matric and osmotic components is then confirmed theoretically. The well-known Kelvin equation for matric suction, and Morse and van't Hoff equations for osmotic suction are subsequently derived from the corresponding thermodynamic equations. The applicability of latter two equations in evaluating the osmotic suctions of cement mortar and concrete is highlighted

  12. Bubble Dynamics and Shock Waves

    CERN Document Server

    2013-01-01

    This volume of the Shock Wave Science and Technology Reference Library is concerned with the interplay between bubble dynamics and shock waves. It is divided into four parts containing twelve chapters written by eminent scientists. Topics discussed include shock wave emission by laser generated bubbles (W Lauterborn, A Vogel), pulsating bubbles near boundaries (DM Leppinen, QX Wang, JR Blake), interaction of shock waves with bubble clouds (CD Ohl, SW Ohl), shock propagation in polydispersed bubbly liquids by model equations (K Ando, T Colonius, CE Brennen. T Yano, T Kanagawa,  M Watanabe, S Fujikawa) and by DNS (G Tryggvason, S Dabiri), shocks in cavitating flows (NA Adams, SJ Schmidt, CF Delale, GH Schnerr, S Pasinlioglu) together with applications involving encapsulated bubble dynamics in imaging (AA Doinikov, A Novell, JM Escoffre, A Bouakaz),  shock wave lithotripsy (P Zhong), sterilization of ships’ ballast water (A Abe, H Mimura) and bubbly flow model of volcano eruptions ((VK Kedrinskii, K Takayama...

  13. Activation of the Saccharomyces cerevisiae filamentation/invasion pathway by osmotic stress in high-osmolarity glycogen pathway mutants

    Science.gov (United States)

    Davenport, K. D.; Williams, K. E.; Ullmann, B. D.; Gustin, M. C.; McIntire, L. V. (Principal Investigator)

    1999-01-01

    Mitogen-activated protein kinase (MAPK) cascades are frequently used signal transduction mechanisms in eukaryotes. Of the five MAPK cascades in Saccharomyces cerevisiae, the high-osmolarity glycerol response (HOG) pathway functions to sense and respond to hypertonic stress. We utilized a partial loss-of-function mutant in the HOG pathway, pbs2-3, in a high-copy suppressor screen to identify proteins that modulate growth on high-osmolarity media. Three high-copy suppressors of pbs2-3 osmosensitivity were identified: MSG5, CAK1, and TRX1. Msg5p is a dual-specificity phosphatase that was previously demonstrated to dephosphorylate MAPKs in yeast. Deletions of the putative MAPK targets of Msg5p revealed that kss1delta could suppress the osmosensitivity of pbs2-3. Kss1p is phosphorylated in response to hyperosmotic shock in a pbs2-3 strain, but not in a wild-type strain nor in a pbs2-3 strain overexpressing MSG5. Both TEC1 and FRE::lacZ expressions are activated in strains lacking a functional HOG pathway during osmotic stress in a filamentation/invasion-pathway-dependent manner. Additionally, the cellular projections formed by a pbs2-3 mutant on high osmolarity are absent in strains lacking KSS1 or STE7. These data suggest that the loss of filamentation/invasion pathway repression contributes to the HOG mutant phenotype.

  14. Quality and sensorial characteristics of osmotically dehydrated mango with syrups of inverted sugar and sucrose

    OpenAIRE

    Bernardi,Sabrina; Bodini,Renata B.; Marcatti,Bruna; Petrus,Rodrigo Rodrigues; Favaro-Trindade,Carmen Sílvia

    2009-01-01

    Osmotic dehydration is becoming more popular as a complementary treatment in the processing of dehydrated foods, since it presents some advantages such as minimising heat damage to the colour and flavour, inhibiting enzymatic browning and thus dispensing the addition of sulphite and, mainly, reducing energy costs. The objective of the present study was to evaluate the effect of using inverted sugar and sucrose syrups as osmotic agents in the dehydration of mango. The conditions used in the de...

  15. Using miniature osmotic infusion pumps to maintain tritiated thymidine exposure to cells in culture

    International Nuclear Information System (INIS)

    Neely, J.E.; Hake, D.A.

    1982-01-01

    To provide a constant level of tracer doses of tritiated thymidine to cultured cells during continuous infusion, miniature osmotic infusion pumps were used to provide replacement thymidine. By determining the loss of isotope from the media during nonreplacement, the rate of constant infusion replacement to maintain thymidine levels was calculated. The replacement rates were similar for the three cell lines examined and allowed a standard osmotic pump infusion

  16. The osmotic stress response of split influenza vaccine particles in an acidic environment

    OpenAIRE

    Choi, Hyo-Jick; Kim, Min-Chul; Kang, Sang-Moo; Montemagno, Carlo D.

    2013-01-01

    Oral influenza vaccine provides an efficient means of preventing seasonal and pandemic disease. In this work, the stability of envelope-type split influenza vaccine particles in acidic environments has been investigated. Owing to the fact that hyper-osmotic stress can significantly affect lipid assembly of vaccine, osmotic stress-induced morphological change of split vaccine particles, in conjunction with structural change of antigenic proteins, was investigated by the use of stopped-flow lig...

  17. Salt-induced osmotic stress for lipid overproduction in batch culture ...

    African Journals Online (AJOL)

    Effect of NaCl-induced osmotic stress on lipid production was investigated in batch culture of Chlorella vulgaris. Based on the facts that NaCl stress improved lipid production but inhibited cells growth at the same times, the novel strategies of multiple osmotic stresses with different NaCl additions (2 g/L at 80 h, 4 g/L at 100 h, ...

  18. A model of strategic marketing alliances for hospices: vertical, internal, osmotic alliances and the complete model.

    Science.gov (United States)

    Starnes, B J; Self, D R

    1999-01-01

    This article develops two previous research efforts. William J. Winston (1994, 1995) has proposed a set of strategies by which health care organizations can benefit from forging strategic alliances. Raadt and Self (1997) have proposed a classification model of alliances including horizontal, vertical, internal, and osmotic. In the second of two articles, this paper presents a model of vertical, internal, and osmotic alliances. Advantages and disadvantages of each are discussed. Finally, the complete alliance system model is presented.

  19. Studies of osmotic diarrhea induced in normal subjects by ingestion of polyethylene glycol and lactulose.

    OpenAIRE

    Hammer, H F; Santa Ana, C A; Schiller, L R; Fordtran, J S

    1989-01-01

    The purpose of these studies was to gain insight into the pathophysiology of pure osmotic diarrhea and the osmotic diarrhea caused by carbohydrate malabsorption. Diarrhea was induced in normal volunteers by ingestion of polyethylene glycol (PEG), which is nonabsorbable, not metabolized by colonic bacteria, and carries no electrical charge. In PEG-induced diarrhea, (a) stool weight was directly correlated with the total mass of PEG ingested; (b) PEG contributed 40-60% of the osmolality of the ...

  20. Direct measurement of osmotic pressure of glycosaminoglycan solutions by membrane osmometry at room temperature.

    Science.gov (United States)

    Chahine, Nadeen O; Chen, Faye H; Hung, Clark T; Ateshian, Gerard A

    2005-09-01

    Articular cartilage is a hydrated soft tissue composed of negatively charged proteoglycans fixed within a collagen matrix. This charge gradient causes the tissue to imbibe water and swell, creating a net osmotic pressure that enhances the tissue's ability to bear load. In this study we designed and utilized an apparatus for directly measuring the osmotic pressure of chondroitin sulfate, the primary glycosaminoglycan found in articular cartilage, in solution with varying bathing ionic strength (0.015 M, 0.15 M, 0.5 M, 1 M, and 2 M NaCl) at room temperature. The osmotic pressure (pi) was found to increase nonlinearly with increasing chondroitin sulfate concentration and decreasing NaCl ionic bath environment. Above 1 M NaCl, pi changes negligibly with further increases in salt concentration, suggesting that Donnan osmotic pressure is negligible above this threshold, and the resulting pressure is attributed to configurational entropy. Results of the current study were also used to estimate the contribution of osmotic pressure to the stiffness of cartilage based on theoretical and experimental considerations. Our findings indicate that the osmotic pressure resulting from configurational entropy is much smaller in cartilage (based on an earlier study on bovine articular cartilage) than in free solution. The rate of change of osmotic pressure with compressive strain is found to contribute approximately one-third of the compressive modulus (H(A)(eff)) of cartilage (Pi approximately H(A)(eff)/3), with the balance contributed by the intrinsic structural modulus of the solid matrix (i.e., H(A) approximately 2H(A)(eff)/3). A strong dependence of this intrinsic modulus on salt concentration was found; therefore, it appears that proteoglycans contribute structurally to the magnitude of H(A), in a manner independent of osmotic pressure.

  1. Prediction of colloid osmotic pressure in renal patients.

    Science.gov (United States)

    Geranton, F; Chantrel, F; Bouiller, M; Muller, S; Kolb, I; Moulin, B; Hannedouche, T

    2000-04-01

    Colloid osmotic pressure (COP) plays a major role in transcapillary fluid shift, including in the glomerular capillary. However, COP is generally estimated by quadratic equations derived from total plasma protein and/or albumin concentrations. The aim of this study was to assess the accuracy of such equations, and to determine the potential role of liver-derived non-albumin proteins in the maintenance of COP, especially in patients presenting a nephrotic syndrome. COP was directly assessed with an osmometer in 170 patients (347 samples), and the results compared with calculated COP, using 4 previously published formulas [Brenner 1972, Canaan-Kühl 1993, Landis-Pappenheimer 1963, Navar 1977]. The 4 calculated COP values were strongly correlated with measured COP (range r = 0.88 - 0.96). However, in absolute terms, measured COP differed significantly from each of the 4 calculated mean values of COP (p equation was: COP(mmHg) = 6.89 x (albumin + fibrinogen) (g/dl) - 5.68. None of the 4 most commonly used formulas correctly predicted COP, and direct measurement of COP is still preferable for research studies. The introduction of fibrinogen into the formula estimating COP leads to higher accuracy, and therefore represents a more convenient model for routine evaluation.

  2. Miniature osmotic actuators for controlled maxillofacial distraction osteogenesis

    Science.gov (United States)

    Li, Yu-Hsien; Su, Yu-Chuan

    2010-06-01

    We have successfully demonstrated miniature actuators that are capable of converting chemical potential directly into steady mechanical movements for maxillofacial distraction osteogenesis. Pistons and diaphragms powered by osmosis are employed to provide the desired linear and volumetric displacements for bone distraction and potentially the release of bone morphogenetic proteins, respectively. The cylindrical-shaped miniature actuators are composed of polymeric materials and fabricated by molding and assembly processes. In the prototype demonstration, vapor-permeable thermoplastic polyurethane was employed as the semi-permeable material. 3 cm long actuators with piston and diaphragm radii of 1 mm and 500 µm, respectively, were fabricated and characterized. The maximum distraction force from the piston-type actuator is found to be 6 N while the piston travels at a constant velocity of 32 µm h-1 (or 0.77 mm/day) for about 1 week. Meanwhile, the release rate from the diaphragm-type actuator is measured to be constant, 0.15 µl h-1 (or 3.6 µl/day), throughout the experiment. Moreover, the sizes and output characteristics of the self-regulating actuators could readily be tailored to realize optimal distraction rate, rhythm and osteogenic activity. As such, the demonstrated miniature osmotic actuators could potentially serve as versatile apparatuses for maxillofacial distraction osteogenesis and fulfill the needs of a variety of implantable and biomedical applications.

  3. Artificial neural network model of pork meat cubes osmotic dehydratation

    Directory of Open Access Journals (Sweden)

    Pezo Lato L.

    2013-01-01

    Full Text Available Mass transfer of pork meat cubes (M. triceps brachii, shaped as 1x1x1 cm, during osmotic dehydration (OD and under atmospheric pressure was investigated in this paper. The effects of different parameters, such as concentration of sugar beet molasses (60-80%, w/w, temperature (20-50ºC, and immersion time (1-5 h in terms of water loss (WL, solid gain (SG, final dry matter content (DM, and water activity (aw, were investigated using experimental results. Five artificial neural network (ANN models were developed for the prediction of WL, SG, DM, and aw in OD of pork meat cubes. These models were able to predict process outputs with coefficient of determination, r2, of 0.990 for SG, 0.985 for WL, 0.986 for aw, and 0.992 for DM compared to experimental measurements. The wide range of processing variables considered for the formulation of these models, and their easy implementation in a spreadsheet calculus make it very useful and practical for process design and control.

  4. The long-term studies of osmotic membrane distillation.

    Science.gov (United States)

    Gryta, Marek

    2018-01-01

    The results of osmotic membrane distillation carried out for 2.5 years were presented in this work. The influence of the process conditions, such as temperature and brine concentration on the permeate flux, was investigated. The saturated NaCl solutions and distilled water were used as a stripping solution and feed, respectively. A continuous regeneration of stripping solution was conducted using a method of natural evaporation from the surface of Białecki rings to the air surrounding the installation. The possibilities of application of Accurel PP S6/2 hydrophobic polypropylene membranes were tested. It was studied whether a saturation stripping solution does not cause scaling and wettability of membranes. It was found that most of the pores in the used membranes were non-wetted, and the salt retention over 99% was maintained during a study period. However, the obtained permeate flux was decreased by 10-20%. The SEM examinations revealed that it was caused by amorphous deposit, which was formed on the membrane surface on the brine side. The SEM-EDS analysis demonstrated that the deposit composition mainly included Si and O.

  5. Sandwich-structured hollow fiber membranes for osmotic power generation

    KAUST Repository

    Fu, Feng Jiang

    2015-11-01

    In this work, a novel sandwich-structured hollow fiber membrane has been developed via a specially designed spinneret and optimized spinning conditions. With this specially designed spinneret, the outer layer, which is the most crucial part of the sandwich-structured membrane, is maintained the same as the traditional dual-layer membrane. The inner substrate layer is separated into two layers: (1) an ultra-thin middle layer comprising a high molecular weight polyvinylpyrrolidone (PVP) additive to enhance integration with the outer polybenzimidazole (PBI) selective layer, and (2) an inner-layer to provide strong mechanical strength for the membrane. Experimental results show that a high water permeability and good mechanical strength could be achieved without the expensive post treatment process to remove PVP which was necessary for the dual-layer pressure retarded osmosis (PRO) membranes. By optimizing the composition, the membrane shows a maximum power density of 6.23W/m2 at a hydraulic pressure of 22.0bar when 1M NaCl and 10mM NaCl are used as the draw and feed solutions, respectively. To our best knowledge, this is the best phase inversion hollow fiber membrane with an outer selective PBI layer for osmotic power generation. In addition, this is the first work that shows how to fabricate sandwich-structured hollow fiber membranes for various applications. © 2015 Elsevier B.V.

  6. POSTURAL SHOCK IN PREGNANCY

    Science.gov (United States)

    Wilkening, Ralph L.; Knauer, John; Larson, Roger K.

    1955-01-01

    Signs and symptoms of shock may be produced in some patients in late pregnancy by putting them in the dorsal recumbent posture. Change from this position will relieve the condition. The features of the supine hypotensive syndrome can be duplicated by applying pressure to the abdomen with the patient in a lateral position. The postural variations of venous pressure, blood pressure, and pulse appear to be due to obstruction of venous return from the lower portion of the body caused by the large uterus of late pregnancy compressing the vena cava. When shock is observed in a woman in late pregnancy, she should be turned to a lateral position before more active measures of treatment are begun. ImagesFigure 1. PMID:14351983

  7. Radiative relativistic shock adiabate

    International Nuclear Information System (INIS)

    Tsintsadze, L.N.; Nishikawa, K.

    1997-01-01

    The influences of thermal radiation on the state equation of shock waves, derived in the previous paper [L. N. Tsintsadze, Phys. Plasmas 2, 4462 (1995)], are studied and a series of relations of thermodynamic quantities that hold for shock waves are derived. It is shown that the presence of radiation can strongly change the compressibility of the plasma. It is well known that for polytropic gases the compressibility cannot change more than four times the initial value in the case of nonrelativistic temperatures. The numerical calculations show that there are no such restrictions, when the radiation energy exceeds the kinetic energy of the plasma. The ultrarelativistic temperature range is also covered in our numerical calculations. Also studied are the influences of the radiation on the PT and the TV diagrams. A significant modification due to radiation is found in every case studied. copyright 1997 American Institute of Physics

  8. Social amoebae mating types do not invest unequally in sexual offspring.

    Science.gov (United States)

    Douglas, T E; Queller, D C; Strassmann, J E

    2017-05-01

    Unequal investment by different sexes in their progeny is common and includes differential investment in the zygote and differential care of the young. The social amoeba Dictyostelium discoideum has a sexual stage in which isogamous cells of any two of the three mating types fuse to form a zygote which then attracts hundreds of other cells to the macrocyst. The latter cells are cannibalized and so make no genetic contribution to reproduction. Previous literature suggests that this sacrifice may be induced in cells of one mating type by cells of another, resulting in a higher than expected production of macrocysts when the inducing type is rare and giving a reproductive advantage to this social cheat. We tested this hypothesis in eight trios of field-collected clones of each of the three D. discoideum mating types by measuring macrocyst production at different pairwise frequencies. We found evidence that supported differential contribution in only two of the 24 clone pairs, so this pattern is rare and clone-specific. In general, we did not reject the hypothesis that the mating types contribute cells relative to their proportion in the population. We also found a significant quadratic relationship between partner frequency and macrocyst production, suggesting that when one clone is rare, macrocyst production is limited by partner availability. We were also unable to replicate previous findings that macrocyst production could be induced in the absence of a compatible mating partner. Overall, mating type-specific differential investment during sex is unlikely in microbial eukaryotes like D. discoideum. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

  9. Exposure to synthetic gray water inhibits amoeba encystation and alters expression of Legionella pneumophila virulence genes.

    Science.gov (United States)

    Buse, Helen Y; Lu, Jingrang; Ashbolt, Nicholas J

    2015-01-01

    Water conservation efforts have focused on gray water (GW) usage, especially for applications that do not require potable water quality. However, there is a need to better understand environmental pathogens and their free-living amoeba (FLA) hosts within GW, given their growth potential in stored gray water. Using synthetic gray water (sGW) we examined three strains of the water-based pathogen Legionella pneumophila and its FLA hosts Acanthamoeba polyphaga, A. castellanii, and Vermamoeba vermiformis. Exposure to sGW for 72 h resulted in significant inhibition (P vermiformis (1 versus 92%), suggesting sGW induced maintenance of the actively feeding trophozoite form. During sGW exposure, L. pneumophila culturability decreased as early as 5 h (1.3 to 2.9 log10 CFU, P < 0.001) compared to controls (Δ0 to 0.1 log10 CFU) with flow cytometric analysis revealing immediate changes in membrane permeability. Furthermore, reverse transcription-quantitative PCR was performed on total RNA isolated from L. pneumophila cells at 0 to 48 h after sGW incubation, and genes associated with virulence (gacA, lirR, csrA, pla, and sidF), the type IV secretion system (lvrB and lvrE), and metabolism (ccmF and lolA) were all shown to be differentially expressed. These results suggest that conditions within GW may promote interactions between water-based pathogens and FLA hosts, through amoebal encystment inhibition and alteration of bacterial gene expression, thus warranting further exploration into FLA and L. pneumophila behavior in GW systems. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  10. Arcellacea (testate amoebae) as bio-indicators of road salt contamination in lakes.

    Science.gov (United States)

    Roe, Helen M; Patterson, R Timothy

    2014-08-01

    Winter deicing operations occur extensively in mid- to high-latitude metropolitan regions around the world and result in a significant reduction in road accidents. Deicing salts can, however, pose a major threat to water quality and aquatic organisms. In this paper, we examine the utility of Arcellacea (testate amoebae) for monitoring lakes that have become contaminated by winter deicing salts, particularly sodium chloride. We analysed 50 sediment samples and salt-related water property variables (chloride concentrations; conductivity) from 15 lakes in the Greater Toronto Area and adjacent areas of southern Ontario, Canada. The sampled lakes included lakes in proximity to major highways and suburban roads and control lakes in forested settings away from road influences. Samples from the most contaminated lakes, with chloride concentrations in excess of 400 mg/l and conductivities of >800 μS/cm, were dominated by species typically found in brackish and/or inhospitable lake environments and by lower faunal diversities (lowest Shannon diversity index values) than samples with lower readings. Q-R-mode cluster analysis and detrended correspondence analysis (DCA) resulted in the recognition of four assemblage groupings. These reflect varying levels of salt contamination in the study lakes, along with other local influences, including nutrient loading. The response to nutrients can, however, be isolated if the planktic eutrophic indicator species Cucurbitella tricuspis is removed from the counts. The findings show that the group has considerable potential for biomonitoring in salt-contaminated lakes, and their presence in lake sediment cores may provide significant insights into long-term benthic community health, which is integral for remedial efforts.

  11. Presence of Legionella and Free-Living Amoebae in Composts and Bioaerosols from Composting Facilities

    Science.gov (United States)

    Conza, Lisa; Pagani, Simona Casati; Gaia, Valeria

    2013-01-01

    Several species of Legionella cause Legionnaires’ disease (LD). Infection may occur through inhalation of Legionella or amoebal vesicles. The reservoirs of Legionella are water, soil, potting soil and compost. Some species of free-living amoebae (FLA) that are naturally present in water and soil were described as hosts for Legionella. This study aimed to understand whether or not the composting facilities could be sources of community-acquired Legionella infections after development of bioaerosols containing Legionella or FLA. We looked for the presence of Legionella (by co-culture) and FLA (by culture) in composts and bioaerosols collected at four composting facilities located in southern Switzerland. We investigated the association between the presence of Legionella and compost and air parameters and presence of FLA. Legionella spp. (including L. pneumophila) were detected in 69.3% (61/88) of the composts and FLA (mainly Acanthamoeba, Vermamoeba, Naegleria and Stenamoeba) in 92.0% (81/88). L. pneumophila and L. bozemanii were most frequently isolated. FLA as potential host for Legionella spp. were isolated from 40.9% (36/88) of the composts in all facilities. In Legionella-positive samples the temperature of compost was significantly lower (P = 0.012) than in Legionella-negative samples. Of 47 bioaerosol samples, 19.1% (9/47) were positive for FLA and 10.6% (5/47) for L. pneumophila. Composts (62.8%) were positive for Legionella and FLA contemporaneously, but both microorganisms were never detected simultaneously in bioaerosols. Compost can release bioaerosol containing FLA or Legionella and could represent a source of infection of community-acquired Legionella infections for workers and nearby residents. PMID:23844174

  12. An expanded phylogeny of social amoebas (Dictyostelia shows increasing diversity and new morphological patterns

    Directory of Open Access Journals (Sweden)

    Stephenson Steven L

    2011-03-01

    Full Text Available Abstract Background Social Amoebae or Dictyostelia are eukaryotic microbes with a unique life cycle consisting of both uni- and multicellular stages. They have long fascinated molecular, developmental and evolutionary biologists, and Dictyostelium discoideum is now one of the most widely studied eukaryotic microbial models. The first molecular phylogeny of Dictyostelia included most of the species known at the time and suggested an extremely deep taxon with a molecular depth roughly equivalent to Metazoa. The group was also shown to consist of four major clades, none of which correspond to traditional genera. Potential morphological justification was identified for three of the four major groups, on the basis of which tentative names were assigned. Results Over the past four years, the Mycetozoan Global Biodiversity Survey has identified many new isolates that appear to be new species of Dictyostelia, along with numerous isolates of previously described species. We have determined 18S ribosomal RNA gene sequences for all of these new isolates. Phylogenetic analyses of these data show at least 50 new species, and these arise from throughout the dictyostelid tree breaking up many previously isolated long branches. The resulting tree now shows eight well-supported major groups instead of the original four. The new species also expand the known morphological diversity of the previously established four major groups, violating nearly all previously suggested deep morphological patterns. Conclusions A greatly expanded phylogeny of Dictyostelia now shows even greater morphological plasticity at deep taxonomic levels. In fact, there now seem to be no obvious deep evolutionary trends across the group. However at a finer level, patterns in morphological character evolution are beginning to emerge. These results also suggest that there is a far greater diversity of Dictyostelia yet to be discovered, including novel morphologies.

  13. Disruption of MDCK cell tight junctions by the free-living amoeba Naegleria fowleri.

    Science.gov (United States)

    Shibayama, Mineko; Martínez-Castillo, Moisés; Silva-Olivares, Angélica; Galindo-Gómez, Silvia; Navarro-García, Fernando; Escobar-Herrera, Jaime; Sabanero, Myrna; Tsutsumi, Víctor; Serrano-Luna, Jesús

    2013-02-01

    Naegleria fowleri is the aetiological agent of primary amoebic meningoencephalitis. This parasite invades its host by penetrating the olfactory mucosa. However, the mechanism of epithelium penetration is not well understood. In the present study, we evaluated the effect of N. fowleri trophozoites and the non-pathogenic Naegleria gruberi on Madin-Darby canine kidney (MDCK) tight junction proteins, including claudin-1, occludin and ZO-1, as well as on the actin cytoskeleton. Trophozoites from each of the free-living amoeba species were co-cultured with MDCK cells in a 1 : 1 ratio for 1, 3, 6 or 10 h. Light microscopy revealed that N. fowleri caused morphological changes as early as 3 h post-infection in an epithelial MDCK monolayer. Confocal microscopy analysis revealed that after 10 h of co-culture, N. fowleri trophozoites induced epithelial cell damage, which was characterized by changes in the actin apical ring and disruption of the ZO-1 and claudin-1 proteins but not occludin. Western blot assays revealed gradual degradation of ZO-1 and claudin-1 as early as 3 h post-infection. Likewise, there was a drop in transepithelial electrical resistance that resulted in increased epithelial permeability and facilitated the invasion of N. fowleri trophozoites by a paracellular route. In contrast, N. gruberi did not induce alterations in MDCK cells even at 10 h post-infection. Based on these results, we suggest that N. fowleri trophozoites disrupt epithelial monolayers, which could enable their penetration of the olfactory epithelium and subsequent invasion of the central nervous system.

  14. LAMARCKIAN EVOLUTION OF THE GIANT MIMIVIRUS IN ALLOPATRIC LABORATORY CULTURE ON AMOEBAE

    Directory of Open Access Journals (Sweden)

    Philippe eColson

    2012-07-01

    Full Text Available Acanthamoeba polyphaga Mimivirus has been subcultured 150 times on germ-free amoebae. This allopatric niche is very different from that found in the natural environment, where the virus is in competition with many other organisms. In this experiment, substantial gene variability and loss occurred concurrently with the emergence of phenotypically different viruses. We sought to quantify the respective roles of Lamarckian and Darwinian evolution during this experiment. We postulated that the Mimivirus genes that were down-regulated at the beginning of the allopatric laboratory culture and inactivated after 150 passages experienced Lamarckian evolution because phenotypic modifications preceded genotypic modifications, whereas we considered that genes that were highly transcribed in the new niche but were later inactivated obeyed Darwinian rules. We used the total transcript abundances and sequences described for the genes of Mimivirus at the beginning of its laboratory life and after 150 passages in allopatric culture on Acanthamoeba spp. We found a statistically significant positive correlation between the level of gene expression at the beginning of the culture and gene inactivation during the 150 passages. In particular, the mean transcript abundance at baseline was significantly lower for inactivated genes than for unchanged genes (165±589 vs. 470±1,625; p<1e-3, and the mean transcript levels during the replication cycle of Mimivirus M1 were up to 8.5-fold lower for inactivated genes than for unchanged genes. In addition, proteins tended to be less frequently identified from purified virions in their early life in allopatric laboratory culture if they were encoded by variable genes than if they were encoded by conserved genes (9% vs. 15%; p= 0.062. Finally, Lamarckian evolution represented the evolutionary process encountered by 63% of the inactivated genes. Such observations may be explained by the lower level of DNA repair of useless genes.

  15. Amoebae, Giant Viruses, and Virophages Make Up a Complex, Multilayered Threesome

    Directory of Open Access Journals (Sweden)

    Jan Diesend

    2018-01-01

    Full Text Available Viral infection had not been observed for amoebae, until the Acanthamoeba polyphaga mimivirus (APMV was discovered in 2003. APMV belongs to the nucleocytoplasmatic large DNA virus (NCLDV family and infects not only A. polyphaga, but also other professional phagocytes. Here, we review the Megavirales to give an overview of the current members of the Mimi- and Marseilleviridae families and their structural features during amoebal infection. We summarize the different steps of their infection cycle in A. polyphaga and Acanthamoeba castellani. Furthermore, we dive into the emerging field of virophages, which parasitize upon viral factories of the Megavirales family. The discovery of virophages in 2008 and research in recent years revealed an increasingly complex network of interactions between cell, giant virus, and virophage. Virophages seem to be highly abundant in the environment and occupy the same niches as the Mimiviridae and their hosts. Establishment of metagenomic and co-culture approaches rapidly increased the number of detected virophages over the recent years. Genetic interaction of cell and virophage might constitute a potent defense machinery against giant viruses and seems to be important for survival of the infected cell during mimivirus infections. Nonetheless, the molecular events during co-infection and the interactions of cell, giant virus, and virophage have not been elucidated, yet. However, the genetic interactions of these three, suggest an intricate, multilayered network during amoebal (co-infections. Understanding these interactions could elucidate molecular events essential for proper viral factory activity and could implicate new ways of treating viruses that form viral factories.

  16. Presence of Legionella and free-living Amoebae in composts and bioaerosols from composting facilities.

    Directory of Open Access Journals (Sweden)

    Lisa Conza

    Full Text Available Several species of Legionella cause Legionnaires' disease (LD. Infection may occur through inhalation of Legionella or amoebal vesicles. The reservoirs of Legionella are water, soil, potting soil and compost. Some species of free-living amoebae (FLA that are naturally present in water and soil were described as hosts for Legionella. This study aimed to understand whether or not the composting facilities could be sources of community-acquired Legionella infections after development of bioaerosols containing Legionella or FLA. We looked for the presence of Legionella (by co-culture and FLA (by culture in composts and bioaerosols collected at four composting facilities located in southern Switzerland. We investigated the association between the presence of Legionella and compost and air parameters and presence of FLA. Legionella spp. (including L. pneumophila were detected in 69.3% (61/88 of the composts and FLA (mainly Acanthamoeba, Vermamoeba, Naegleria and Stenamoeba in 92.0% (81/88. L. pneumophila and L. bozemanii were most frequently isolated. FLA as potential host for Legionella spp. were isolated from 40.9% (36/88 of the composts in all facilities. In Legionella-positive samples the temperature of compost was significantly lower (P = 0.012 than in Legionella-negative samples. Of 47 bioaerosol samples, 19.1% (9/47 were positive for FLA and 10.6% (5/47 for L. pneumophila. Composts (62.8% were positive for Legionella and FLA contemporaneously, but both microorganisms were never detected simultaneously in bioaerosols. Compost can release bioaerosol containing FLA or Legionella and could represent a source of infection of community-acquired Legionella infections for workers and nearby residents.

  17. Presence of Legionella and free-living Amoebae in composts and bioaerosols from composting facilities.

    Science.gov (United States)

    Conza, Lisa; Pagani, Simona Casati; Gaia, Valeria

    2013-01-01

    Several species of Legionella cause Legionnaires' disease (LD). Infection may occur through inhalation of Legionella or amoebal vesicles. The reservoirs of Legionella are water, soil, potting soil and compost. Some species of free-living amoebae (FLA) that are naturally present in water and soil were described as hosts for Legionella. This study aimed to understand whether or not the composting facilities could be sources of community-acquired Legionella infections after development of bioaerosols containing Legionella or FLA. We looked for the presence of Legionella (by co-culture) and FLA (by culture) in composts and bioaerosols collected at four composting facilities located in southern Switzerland. We investigated the association between the presence of Legionella and compost and air parameters and presence of FLA. Legionella spp. (including L. pneumophila) were detected in 69.3% (61/88) of the composts and FLA (mainly Acanthamoeba, Vermamoeba, Naegleria and Stenamoeba) in 92.0% (81/88). L. pneumophila and L. bozemanii were most frequently isolated. FLA as potential host for Legionella spp. were isolated from 40.9% (36/88) of the composts in all facilities. In Legionella-positive samples the temperature of compost was significantly lower (P = 0.012) than in Legionella-negative samples. Of 47 bioaerosol samples, 19.1% (9/47) were positive for FLA and 10.6% (5/47) for L. pneumophila. Composts (62.8%) were positive for Legionella and FLA contemporaneously, but both microorganisms were never detected simultaneously in bioaerosols. Compost can release bioaerosol containing FLA or Legionella and could represent a source of infection of community-acquired Legionella infections for workers and nearby residents.

  18. The osmotic stress response of split influenza vaccine particles in an acidic environment.

    Science.gov (United States)

    Choi, Hyo-Jick; Kim, Min-Chul; Kang, Sang-Moo; Montemagno, Carlo D

    2014-12-01

    Oral influenza vaccine provides an efficient means of preventing seasonal and pandemic disease. In this work, the stability of envelope-type split influenza vaccine particles in acidic environments has been investigated. Owing to the fact that hyper-osmotic stress can significantly affect lipid assembly of vaccine, osmotic stress-induced morphological change of split vaccine particles, in conjunction with structural change of antigenic proteins, was investigated by the use of stopped-flow light scattering (SFLS), intrinsic fluorescence, transmission electron microscopy (TEM), and hemagglutination assay. Split vaccine particles were found to exhibit a step-wise morphological change in response to osmotic stress due to double-layered wall structure. The presence of hyper-osmotic stress in acidic medium (0.3 osmolarity, pH 2.0) induced a significant level of membrane perturbation as measured by SFLS and TEM, imposing more damage to antigenic proteins on vaccine envelope than can be caused by pH-induced conformational change at acidic iso-osmotic condition. Further supports were provided by the intrinsic fluorescence and hemagglutinin activity measurements. Thus, hyper-osmotic stress becomes an important factor for determining stability of split vaccine particles in acidic medium. These results are useful in better understanding the destabilizing mechanism of split influenza vaccine particles in gastric environment and in designing oral influenza vaccine formulations.

  19. Suppressive effect of cellulose on osmotic diarrhea caused by maltitol in healthy female subjects.

    Science.gov (United States)

    Oku, Tsuneyuki; Hongo, Ryoko; Nakamura, Sadako

    2008-08-01

    Using a single-group time-series design, we determined that osmotic diarrhea caused by maltitol ingestion was suppressed by the addition of not only soluble but also insoluble dietary fiber in healthy humans. We then clarified that cellulose delayed gastric emptying in rats. Twenty-seven healthy volunteers ingested maltitol step-wise at doses of 15, 20, 25, 30, 35, 40 and 45 g from small to large amounts. Within that range of ingested amounts, 22 out of 27 subjects experienced osmotic diarrhea from maltitol ingestion, and the minimal dose level of maltitol that induced osmotic diarrhea (MMD) was established for each subject. When 5 g of cellulose was added to the MMD, osmotic diarrhea was suppressed in 13 out of 19 subjects (68.4%), while partially hydrolyzed alginate-Na (PHA-Na), a soluble dietary fiber, suppressed osmotic diarrhea in 10 out of 20 subjects (50.0%). When a mixed solution of cellulose and maltitol was administered to rats, the gastric emptying of maltitol was significantly delayed at 30 and 60 min after administration (p=0.019, p=0.013), respectively. PHA-Na also significantly delayed gastric emptying at 30 min (p=0.013). In conclusion, cellulose can suppress the osmotic diarrhea caused by maltitol ingestion in humans and delay the gastric emptying of maltitol in rats. A new physiological property of cellulose was clarified in this study.

  20. Osmotic dehydration of Braeburn variety apples in the production of sustainable food products

    Science.gov (United States)

    Ciurzyńska, Agnieszka; Cichowska, Joanna; Kowalska, Hanna; Czajkowska, Kinga; Lenart, Andrzej

    2018-01-01

    The aim of this work was to investigate the effects of osmotic dehydration conditions on the properties of osmotically pre-treated dried apples. The scope of research included analysing the most important mass exchange coefficients, i.e. water loss, solid gain, reduced water content and water activity, as well as colour changes of the obtained dried product. In the study, apples were osmotically dehydrated in one of two 60% solutions: sucrose or sucrose with an addition of chokeberry juice concentrate, for 30 and 120 min, in temperatures of 40 and 60°C. Ultrasound was also used during the first 30 min of the dehydration process. After osmotic pre-treatment, apples were subjected to innovative convective drying with the puffing effect, and to freeze-drying. Temperature and dehydration time increased the effectiveness of mass exchange during osmotic dehydration. The addition of chokeberry juice concentrate to standard sucrose solution and the use of ultrasound did not change the value of solid gain and reduced water content. Water activity of the dried apple tissue was not significantly changed after osmotic dehydration, while changes in colour were significant.

  1. Shock resistance testing

    International Nuclear Information System (INIS)

    Pouard, M.

    1984-03-01

    In the framework of mechanical tests and to answer the different requests for tests, the T.C.R (Transport Conditionnement et Retraitement) laboratory got test facilities. These installations allow to carry out tests of resistance to shocks, mainly at the safety level of components of nuclear power plants, mockups of transport casks for fuel elements and transport containers for radioactive materials. They include a tower and a catapult. This paper give a decription of the facilities and explain their operation way [fr

  2. Characterization of shocked beryllium

    Directory of Open Access Journals (Sweden)

    Papin P.A.

    2012-08-01

    Full Text Available While numerous studies have investigated the low-strain-rate constitutive response of beryllium, the combined influence of high strain rate and temperature on the mechanical behavior and microstructure of beryllium has received limited attention over the last 40 years. In the current work, high strain rate tests were conducted using both explosive drive and a gas gun to accelerate the material. Prior studies have focused on tensile loading behavior, or limited conditions of dynamic strain rate and/or temperature. Two constitutive strength (plasticity models, the Preston-Tonks-Wallace (PTW and Mechanical Threshold Stress (MTS models, were calibrated using common quasi-static and Hopkinson bar data. However, simulations with the two models give noticeably different results when compared with the measured experimental wave profiles. The experimental results indicate that, even if fractured by the initial shock loading, the Be remains sufficiently intact to support a shear stress following partial release and subsequent shock re-loading. Additional “arrested” drive shots were designed and tested to minimize the reflected tensile pulse in the sample. These tests were done to both validate the model and to put large shock induced compressive loads into the beryllium sample.

  3. Evidence of transfer by conjugation of type IV secretion system genes between Bartonella species and Rhizobium radiobacter in amoeba.

    Directory of Open Access Journals (Sweden)

    Watcharee Saisongkorh

    Full Text Available BACKGROUND: Bartonella species cospeciate with mammals and live within erythrocytes. Even in these specific niches, it has been recently suggested by bioinformatic analysis of full genome sequences that Lateral Gene Transfer (LGT may occur but this has never been demonstrated biologically. Here we describe the sequence of the B. rattaustraliani (AUST/NH4(T circular plasmid (pNH4 that encodes the tra cluster of the Type IV secretion system (T4SS and we eventually provide evidence that Bartonella species may conjugate and exchange this plasmid inside amoeba. PRINCIPAL FINDINGS: The T4SS of pNH4 is critical for intracellular viability of bacterial pathogens, exhibits bioinformatic evidence of LGT among bacteria living in phagocytic protists. For instance, 3 out of 4 T4SS encoding genes from pNH4 appear to be closely related to Rhizobiales, suggesting that gene exchange occurs between intracellular bacteria from mammals (bartonellae and plants (Rhizobiales. We show that B. rattaustraliani and Rhizobium radiobacter both survived within the amoeba Acanthamoeba polyphaga and can conjugate together. Our findings further support the hypothesis that tra genes might also move into and out of bacterial communities by conjugation, which might be the primary means of genomic evolution for intracellular adaptation by cross-talk of interchangeable genes between Bartonella species and plant pathogens. CONCLUSIONS: Based on this, we speculate that amoeba favor the transfer of genes as phagocytic protists, which allows for intraphagocytic survival and, as a consequence, promotes the creation of potential pathogenic organisms.

  4. Study of interactions between metal ions and protein model compounds by energy decomposition analyses and the AMOEBA force field

    Science.gov (United States)

    Jing, Zhifeng; Qi, Rui; Liu, Chengwen; Ren, Pengyu

    2017-10-01

    The interactions between metal ions and proteins are ubiquitous in biology. The selective binding of metal ions has a variety of regulatory functions. Therefore, there is a need to understand the mechanism of protein-ion binding. The interactions involving metal ions are complicated in nature, where short-range charge-penetration, charge transfer, polarization, and many-body effects all contribute significantly, and a quantitative description of all these interactions is lacking. In addition, it is unclear how well current polarizable force fields can capture these energy terms and whether these polarization models are good enough to describe the many-body effects. In this work, two energy decomposition methods, absolutely localized molecular orbitals and symmetry-adapted perturbation theory, were utilized to study the interactions between Mg2+/Ca2+ and model compounds for amino acids. Comparison of individual interaction components revealed that while there are significant charge-penetration and charge-transfer effects in Ca complexes, these effects can be captured by the van der Waals (vdW) term in the AMOEBA force field. The electrostatic interaction in Mg complexes is well described by AMOEBA since the charge penetration is small, but the distance-dependent polarization energy is problematic. Many-body effects were shown to be important for protein-ion binding. In the absence of many-body effects, highly charged binding pockets will be over-stabilized, and the pockets will always favor Mg and thus lose selectivity. Therefore, many-body effects must be incorporated in the force field in order to predict the structure and energetics of metalloproteins. Also, the many-body effects of charge transfer in Ca complexes were found to be non-negligible. The absorption of charge-transfer energy into the additive vdW term was a main source of error for the AMOEBA many-body interaction energies.

  5. Hypotonic shock mediation by p38 MAPK, JNK, PKC, FAK, OSR1 and SPAK in osmosensing chloride secreting cells of killifish opercular epithelium

    DEFF Research Database (Denmark)

    Marshall, W. S.; Ossum, Carlo Gunnar; Hoffmann, Else Kay

    2005-01-01

    are not involved. H-89 did not block hypotonic inhibition but decreased the recovery, indicating PKA may be involved in the recovery and overshoot (after restoration of isotonic conditions). SB203580 significantly enhanced the decrease in current by hypotonic shock, suggesting an inhibitory role of p38 MAPK...... analysis) by eightfold at 5 min, then more slowly again to sevenfold at 60 min. Hypertonic shock slowly increased p38 by sevenfold at 60 min. Phosphorylated JNK kinase was increased by 40-50% by both hypotonic and hypertonic shock and was still elevated at 30 min in hypertonic medium. By immunoblot......Hypotonic shock rapidly inhibits Cl- secretion by chloride cells, an effect that is osmotic and not produced by NaCl-depleted isosmotic solutions, yet the mechanism for the inhibition and its recovery are not known. We exposed isolated opercular epithelia, mounted in Ussing chambers, to hypotonic...

  6. Expression profiling on soybean leaves reveals integration of ER- and osmotic-stress pathways

    Directory of Open Access Journals (Sweden)

    Dewey Ralph E

    2007-11-01

    Full Text Available Abstract Background Despite the potential of the endoplasmic reticulum (ER stress response to accommodate adaptive pathways, its integration with other environmental-induced responses is poorly understood in plants. We have previously demonstrated that the ER-stress sensor binding protein (BiP from soybean exhibits an unusual response to drought. The members of the soybean BiP gene family are differentially regulated by osmotic stress and soybean BiP confers tolerance to drought. While these results may reflect crosstalk between the osmotic and ER-stress signaling pathways, the lack of mutants, transcriptional response profiles to stresses and genome sequence information of this relevant crop has limited our attempts to identify integrated networks between osmotic and ER stress-induced adaptive responses. As a fundamental step towards this goal, we performed global expression profiling on soybean leaves exposed to polyethylene glycol treatment (osmotic stress or to ER stress inducers. Results The up-regulated stress-specific changes unmasked the major branches of the ER-stress response, which include enhancing protein folding and degradation in the ER, as well as specific osmotically regulated changes linked to cellular responses induced by dehydration. However, a small proportion (5.5% of total up-regulated genes represented a shared response that seemed to integrate the two signaling pathways. These co-regulated genes were considered downstream targets based on similar induction kinetics and a synergistic response to the combination of osmotic- and ER-stress-inducing treatments. Genes in this integrated pathway with the strongest synergistic induction encoded proteins with diverse roles, such as plant-specific development and cell death (DCD domain-containing proteins, an ubiquitin-associated (UBA protein homolog and NAC domain-containing proteins. This integrated pathway diverged further from characterized specific branches of ER-stress as

  7. Quantitative detection and differentiation of free-living amoeba species using SYBR green-based real-time PCR melting curve analysis.

    Science.gov (United States)

    Behets, Jonas; Declerck, Priscilla; Delaedt, Yasmine; Verelst, Lieve; Ollevier, Frans

    2006-12-01

    Real-time polymerase chain reaction melting curve analysis (MCA) allows differentiation of several free-living amoebae species. Distinctive characteristics were found for Naegleria fowleri, N. lovaniensis, N. australiensis, N. gruberi, Hartmanella vermiformis, and Willaertia magna. Species specificity of the amplicons was confirmed using agarose gel electrophoresis and sequence-based approaches. Amplification efficiency ranged from 91% to 98%, indicating the quantitative potential of the assay. This MCA approach can be used for quantitative detection of free-living amoebae after cultivation but also as a culture-independent detection method.

  8. Thermal shock behaviour of ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Fantozzi, G.; Saadaoui, M.; Chevalier, J.; Olagnon, C. [Groupe d' Etude de Metallurgie Physique UMR, Institut National des Sciences Appliquees de Lyon, Villeurbanne (France)

    2000-07-01

    Thermal shock of ceramics is complex to analyse because of the important number of parameters to take into account. Thermal shock analysis has been refined by considering the dependence with temperature of the different parameters. From the temperature evolution in the specimen, the stress and stress intensity factor (SIF) profiles can be calculated. This allows the prediction of the crack evolution during thermal shock. Thermal shock experiments conducted by using an in-situ acoustic emission (AE) apparatus allow the determination of the time of unstable crack growth. The effect of crack growth resistance (R-curve behaviour) can be taken into account and, if it is significant, the thermal shock resistance of ceramics can be improved. The fracture mechanical analysis was used to determine the R-curve behaviour of alumina material subjected to thermal shock. A good agreement is observed between predictions of thermal fracture theory based on fracture mechanics and experimental results. (orig.)

  9. Sixteen-Day Bedrest Significantly Increases Plasma Colloid Osmotic Pressure

    Science.gov (United States)

    Hargens, Alan R.; Hsieh, S. T.; Murthy, G.; Ballard, R. E.; Convertino, V. A.; Wade, Charles E. (Technical Monitor)

    1994-01-01

    Upon exposure to microgravity, astronauts lose up to 10% of their total plasma volume, which may contribute to orthostatic intolerance after space flight. Because plasma colloid osmotic pressure (COP) is a primary factor maintaining plasma volume, our objective was to measure time course changes in COP during microgravity simulated by 6 deg. head-down tilt (HDT). Seven healthy male subjects (30-55 years of age) were placed in HDT for 16 days. For the purpose of another study, three of the seven subjects were chosen to exercise on a cycle ergometer on day 16. Blood samples were drawn immediately before bedrest on day 14 of bedrest, 18-24 hours following exercise while all subjects were still in HDT and 1 hour following bedrest termination. Plasma COP was measured in all 20 microliter EDTA-treated samples using an osmometer fitted with a PM 30 membrane. Data were analyzed with paired and unpaired t-tests. Plasma COP on day 14 of bedrest (29.9 +/- 0.69 mmHg) was significantly higher (p less than 0.005) than the control, pre-bedrest value (23.1 +/- 0.76 mmHg). At one hour of upright recovery after HDT, plasma COP remained significantly elevated (exercise: 26.9 +/- 0.87 mmHg; no exercise: 26.3 +/- 0.85 mmHg). Additionally, exercise had no significant effect on plasma COP 18-24 hours following exercise (exercise: 27.8 +/- 1.09 mmHg; no exercise: 27.1 +/- 0.78 mmHg). Our results demonstrate that plasma COP increases significantly with microgravity simulated by HDT. However, preliminary results indicate exercise during HDT does not significantly affect plasma COP.

  10. Osmotic and stimulant laxatives for the management of childhood constipation.

    Science.gov (United States)

    Gordon, Morris; MacDonald, John K; Parker, Claire E; Akobeng, Anthony K; Thomas, Adrian G

    2016-08-17

    Constipation within childhood is an extremely common problem. Despite the widespread use of osmotic and stimulant laxatives by health professionals to manage constipation in children, there has been a long standing paucity of high quality evidence to support this practice. We set out to evaluate the efficacy and safety of osmotic and stimulant laxatives used to treat functional childhood constipation. We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, and the Cochrane IBD Group Specialized Trials Register from inception to 10 March 2016. There were no language restrictions. We also searched the references of all included studies, personal contacts and drug companies to identify studies. Randomised controlled trials (RCTs) which compared osmotic or stimulant laxatives to placebo or another intervention, with participants aged 0 to 18 years old were considered for inclusion. The primary outcome was frequency of defecation. Secondary endpoints included faecal incontinence, disimpaction, need for additional therapies and adverse events. Relevant papers were identified and two authors independently assessed the eligibility of trials, extracted data and assessed methodological quality using the Cochrane risk of bias tool. The primary outcome was frequency of defecation. Secondary endpoints included faecal incontinence, disimpaction, need for additional therapies and adverse events. For continuous outcomes we calculated the mean difference (MD) and 95% confidence interval (CI) using a fixed-effect model. For dichotomous outcomes we calculated the risk ratio (RR) and 95% CI using a fixed-effect model. The Chi(2) and I(2) statistics were used to assess statistical heterogeneity. A random-effects model was used in situations of unexplained heterogeneity. We assessed the overall quality of the evidence supporting the primary and secondary outcomes using the GRADE criteria. Twenty-five RCTs (2310 participants) were included in the review. Fourteen

  11. Finnish exchange students' culture shock

    OpenAIRE

    Pekkala, Karoliina

    2015-01-01

    This bachelor’s thesis is written about culture shock experienced by the exchange students from Finland. It is commissioned by an international students exchange organisation located in Finland. The aim of the research was to find out how much the host country affects the culture shock and to identify aspects that affect the adaptation of the students. The goal is to provide the future exchange students with advise on coping with culture shock. Theoretical framework consists of defining w...

  12. Eight Annual Conference on Shock

    Science.gov (United States)

    1985-11-01

    University 2) "Role of Eicosanoids in Disease States Other Than Shock" Perry V. Halushka, MD, PhD Medical University of South Carolina, Charleston 3...anoxemia re- sults in improved myocardial function and augments energy reserves of myocardial gly- cogen(MG). As many patients with heart disease also have...pretreated (30 min) shocked and sham control rats. SAO shock was induced by occlusions of the coeliac and superior mesenteric arteries for 60 mins. Plasma

  13. Effect of Osmotic Pressure on the Stability of Whole Inactivated Influenza Vaccine for Coating on Microneedles.

    Directory of Open Access Journals (Sweden)

    Hyo-Jick Choi

    Full Text Available Enveloped virus vaccines can be damaged by high osmotic strength solutions, such as those used to protect the vaccine antigen during drying, which contain high concentrations of sugars. We therefore studied shrinkage and activity loss of whole inactivated influenza virus in hyperosmotic solutions and used those findings to improve vaccine coating of microneedle patches for influenza vaccination. Using stopped-flow light scattering analysis, we found that the virus underwent an initial shrinkage on the order of 10% by volume within 5 s upon exposure to a hyperosmotic stress difference of 217 milliosmolarity. During this shrinkage, the virus envelope had very low osmotic water permeability (1 - 6×10-4 cm s-1 and high Arrhenius activation energy (Ea = 15.0 kcal mol-1, indicating that the water molecules diffused through the viral lipid membranes. After a quasi-stable state of approximately 20 s to 2 min, depending on the species and hypertonic osmotic strength difference of disaccharides, there was a second phase of viral shrinkage. At the highest osmotic strengths, this led to an undulating light scattering profile that appeared to be related to perturbation of the viral envelope resulting in loss of virus activity, as determined by in vitro hemagglutination measurements and in vivo immunogenicity studies in mice. Addition of carboxymethyl cellulose effectively prevented vaccine activity loss in vitro and in vivo, believed to be due to increasing the viscosity of concentrated sugar solution and thereby reducing osmotic stress during coating of microneedles. These results suggest that hyperosmotic solutions can cause biphasic shrinkage of whole inactivated influenza virus which can damage vaccine activity at high osmotic strength and that addition of a viscosity enhancer to the vaccine coating solution can prevent osmotically driven damage and thereby enable preparation of stable microneedle coating formulations for vaccination.

  14. Paravannella minima n. g. n. sp. (Discosea, Vannellidae) and distinction of the genera in the vannellid amoebae.

    Science.gov (United States)

    Kudryavtsev, Alexander

    2014-06-01

    Paravannella minima n. g. n. sp. (Amoebozoa, Vannellidae) isolated from a freshwater aquarium, possesses all light-microscopic and ultrastructural characteristics of the genus Vannella, being one of the smallest species among the vannellid amoebae (cell size during locomotion usually between 4.5 and 10μm). At the same time, sequence analysis of the genes encoding for nuclear SSU rRNA, actin and mitochondrial Cox1 shows this species as the earliest-branching vannellid that appears to be sister to the rest of this clade. This is correlated with the presence of some plesiomorphic characters; in particular, the secondary structure of the hypervariable helices E23-1-E23-7 in the studied species is shared with Vannella and most of the genera of Dactylopodida. The cell coat structure of the studied species corresponds to the hypothesis that vannellid amoebae were ancestrally enclosed in a cell coat consisting of pentagonal glycostyles that have undergone multiple independent losses in various clades of Vannellidae. Copyright © 2013 Elsevier GmbH. All rights reserved.

  15. Ptolemeba n. gen., a novel genus of hartmannellid amoebae (Tubulinea, Amoebozoa); with an emphasis on the taxonomy of Saccamoeba.

    Science.gov (United States)

    Watson, Pamela M; Sorrell, Stephanie C; Brown, Matthew W

    2014-01-01

    Hartmannellid amoebae are an unnatural assemblage of amoeboid organisms that are morphologically difficult to discern from one another. In molecular phylogenetic trees of the nuclear-encoded small subunit rDNA, they occupy at least five lineages within Tubulinea, a well-supported clade in Amoebozoa. The polyphyletic nature of the hartmannellids has led to many taxonomic problems, in particular paraphyletic genera. Recent taxonomic revisions have alleviated some of the problems. However, the genus Saccamoeba is paraphyletic and is still in need of revision as it currently occupies two distinct lineages. Here, we report a new clade on the tree of Tubulinea, which we infer represents a novel genus that we name Ptolemeba n. gen. This genus subsumes a clade of hartmannellid amoebae that were previously considered in the genus Saccamoeba, but whose mitochondrial morphology is distinct from Saccamoeba. In accordance with previous research, we formalize the clade as distinct from Saccamoeba. Transmission electron microscopy of our isolates illustrate that both molecularly discrete species can be further differentiated by their unique mitochondrial cristal morphology. © 2014 The Author(s) Journal of Eukaryotic Microbiology © 2014 International Society of Protistologists.

  16. The reconstruction of late Holocene depth-to-water-table based on testate amoebae in an eastern Australian mire

    Science.gov (United States)

    Zheng, X.; Money, S.; Hope, G.

    2017-12-01

    There are relatively few quantitative palaeo-hydrological records available in eastern Australia, and those that are available, for example from dendroclimatology and the reconstruction of lake level, are often relatively short or have a relatively coarse temporal resolution (e.g. Wilkins et al. 2013; Palmer et al. 2015). Testate amoebae, a widely used hydrological proxy in the Northern Hemisphere, were used here to reconstruct depth to water table (DWT) at Snowy Flat, which is a Sphagnum-Richea-Empodismahigh altitude (1618 m asl) shrub bog in the Australian Capital Territory, Australia. Testate amoebae were quantified in a Snowy Flat core representing 4,200 cal Y BP and the community composition was used to reconstruct DWT based on our recently established transfer functions. Results from three different types of transfer functions (Fig. 1) consistently show there was a decreasing DWT (wetter) period centred on about 3350 cal Y BP, a trend towards increased dryness from about 3300 to 2200 cal Y BP and a distinctly drier period 850 to 700 cal Y BP which was immediately followed by a wetter period from 700 to 500 cal Y BP. We discuss these episodes and trends in relation to the drivers of climatic variability in this region and in particular, by comparing our results with other south-eastern Australia records, comment on the history of the southern annular mode.

  17. Myths of "shock therapy".

    Science.gov (United States)

    Fink, M

    1977-09-01

    The author discusses the myths of the ECT process--that shock and the convulsion are essential, memory loss and brain damage are inescapable, and little is known of the process--and assesses the fallacies in these ideas. Present views of the ECT process suggest that its mode of action in depression may best be described as a prolonged form of diencephalic stimulation, particularly useful to affect the hypothalamic dysfunctions that characterize depressive illness. The author emphasizes the need for further study of this treatment modality and for self-regulation by the profession.

  18. Loss of Cln3 impacts protein secretion in the social amoeba Dictyostelium.

    Science.gov (United States)

    Huber, Robert J

    2017-07-01

    Neuronal ceroid lipofuscinosis (NCL), also referred to as Batten disease, is the most common form of childhood neurodegeneration. Mutations in CLN3 cause the most prevalent subtype of the disease, which manifests during early childhood and is currently untreatable. The precise function of the CLN3 protein is still not known, which has inhibited the development of targeted therapies. In the social amoeba Dictyostelium discoideum, loss of the CLN3 homolog, Cln3, reduces adhesion during early development, which delays streaming and aggregation. The results of the present study indicate that this phenotype may be at least partly due to aberrant protein secretion in cln3 - cells. It is well-established that Cln3 localizes primarily to the contractile vacuole (CV) system in Dictyostelium, and to a lesser extent, compartments of the endocytic pathway. Intriguingly, the CV system has been linked to the secretion of proteins that do not contain a signal peptide for secretion (i.e., unconventional protein secretion). Proteins that do contain a signal peptide are secreted via a conventional mechanism involving the endoplasmic reticulum, transport through the Golgi, and secretion via vesicle release. In this study, Cln3 was observed to co-localize with the Golgi marker wheat germ agglutinin suggesting that Cln3 participates in both secretion mechanisms. Chimeras of wild-type (WT) and cln3 - cells displayed delayed streaming and aggregation, and interestingly, cln3 - cells starved in conditioned media (CM) harvested from starving WT cells showed near normal timing of streaming and aggregation suggesting aberrant protein secretion in Cln3-deficient cells. Based on these observations, LC-MS/MS was used to reveal the protein content of CM from starved cells (mass spectrometry data are available via ProteomeXchange with identifier PXD004897). A total of 450 proteins were detected in WT and cln3 - CM, of which 3 were absent in cln3 - CM. Moreover, 12 proteins that were present in

  19. Sorbitol treatment extends lifespan and induces the osmotic stress response in Caenorhabditis elegans

    Directory of Open Access Journals (Sweden)

    Devon eChandler-Brown

    2015-10-01

    Full Text Available The response to osmotic stress is a highly conserved process for adapting to changing environmental conditions. Prior studies have shown that hyperosmolarity by addition of sorbitol to the growth medium is sufficient to increase both chronological and replicative lifespan in the budding yeast, Saccharomyces cerevisiae. Here we report a similar phenomenon in the nematode Caenorhabditis elegans. Addition of sorbitol to the nematode growth medium induces an adaptive osmotic response and increases C. elegans lifespan by about 35%. Lifespan extension from 5% sorbitol behaves similarly to dietary restriction in a variety of genetic backgrounds, increasing lifespan additively with mutation of daf-2(e1370 and independently of daf-16(mu86, sir-2.1(ok434, aak-2(ok524, and hif-1(ia04. Dietary restriction by bacterial deprivation or mutation of eat-2(ad1113 fails to further extend lifespan in the presence of 5% sorbitol. Two mutants with constitutive activation of the osmotic response, osm-5(p813 and osm-7(n1515, were found to be long-lived, and lifespan extension from sorbitol required the glycerol biosynthetic enzymes GPDH-1 and GPDH-2. Taken together, these observations demonstrate that exposure to sorbitol at levels sufficient to induce an adaptive osmotic response extends lifespan in worms and define the osmotic stress response pathway as a longevity pathway conserved between yeast and nematodes.

  20. Cystic fibrosis airway secretions exhibit mucin hyperconcentration and increased osmotic pressure

    Science.gov (United States)

    Henderson, Ashley G.; Ehre, Camille; Button, Brian; Abdullah, Lubna H.; Cai, Li-Heng; Leigh, Margaret W.; DeMaria, Genevieve C.; Matsui, Hiro; Donaldson, Scott H.; Davis, C. William; Sheehan, John K.; Boucher, Richard C.; Kesimer, Mehmet

    2014-01-01

    The pathogenesis of mucoinfective lung disease in cystic fibrosis (CF) patients likely involves poor mucus clearance. A recent model of mucus clearance predicts that mucus flow depends on the relative mucin concentration of the mucus layer compared with that of the periciliary layer; however, mucin concentrations have been difficult to measure in CF secretions. Here, we have shown that the concentration of mucin in CF sputum is low when measured by immunologically based techniques, and mass spectrometric analyses of CF mucins revealed mucin cleavage at antibody recognition sites. Using physical size exclusion chromatography/differential refractometry (SEC/dRI) techniques, we determined that mucin concentrations in CF secretions were higher than those in normal secretions. Measurements of partial osmotic pressures revealed that the partial osmotic pressure of CF sputum and the retained mucus in excised CF lungs were substantially greater than the partial osmotic pressure of normal secretions. Our data reveal that mucin concentration cannot be accurately measured immunologically in proteolytically active CF secretions; mucins are hyperconcentrated in CF secretions; and CF secretion osmotic pressures predict mucus layer–dependent osmotic compression of the periciliary liquid layer in CF lungs. Consequently, mucin hypersecretion likely produces mucus stasis, which contributes to key infectious and inflammatory components of CF lung disease. PMID:24892808

  1. A review on controlled porosity osmotic pump tablets and its evaluation

    Directory of Open Access Journals (Sweden)

    Chinmaya Keshari Sahoo

    2015-12-01

    Full Text Available Conventional drug delivery system provides an immediate release of drug which does not control the release of the drug and does not maintain effective concentration at target site for a longer period of time. Hence to avoid the shortcomings there is development of various controlled drug delivery systems. Among these osmotic drug delivery system (ODDS utilizes the principle of osmotic pressure and delivers drug dose in an optimized manner to maintain drug concentration within the therapeutic window and minimizes toxic effects. ODDS releases drug at a controlled rate that is independent of the pH and thermodynamics of dissolution medium. The release of drug from ODDS follows zero order kinetics. The release of drug from osmotic system depends upon various formulation factors such as solubility, osmotic pressure of the core components, size of the delivery orifice and nature of the rate controlling membrane. Controlled porosity osmotic pump (CPOP contains drug, osmogens, excipients in core and a coating of semipermeable membrane with water soluble additives. In CPOP water soluble additives dissolve after coming in contact with water, resulting in an in situ formation of a microporous membrane. The present study gives an idea about osmosis, CPOP, components of CPOP and its evaluation.

  2. THE IMPORTANCE OF THE ERYTHROCYTES OSMOTIC FRAGILITY TEST PERFORMED IN CHILDREN WITH INDIRECT HYPERBILIRUB1NEMIA

    Directory of Open Access Journals (Sweden)

    Ivana Stojanović

    2005-07-01

    Full Text Available The osmotic fragility test of erythrocytes is useful in the diagnosis of different types of hereditary hemolytic anemias followed with hyperbilirubinemia. Hemolytic anemias, characterized by accelerated destruction of red blood cells, are usually the consequence of many metabolic abnormalities like cellular membrane defect, erythrocyte enzymes defect or hemoglobin abnormalities – hemoglobinopathies. The object of our study was to assess the relationship between osmotic fragility test of erythrocytes and severity of indirect hyperbilirubinemia in some inherited erythrocytes’ disorders. We did the osmotic fragility test of erythrocytes by using Dacie, s method with normal values of erythrocytes hemolysis between 0,48 to 0,34% NaCl (minimal to maximal hemolysis. In hereditary spherocytosis, fragility of erythrocytes was increased (min. at 0,50 % NaCl to max. 0,44 % NaCl . In the child with β- thalassemia and cycle cell anemia erythrocytes fragility was decreased (min . at 0,42 to max. 0,32 % NaCl, that is 0,40% min. of hemolysis and 0,34% max. hemolysis in the second case. In newborn infants with high levels of indirect bilirubin in serum as a cause of physiological jaundice, the osmotic fragility test was within a normal range. Our findings point out the diagnostic value of osmotic fragility test in assessing patients with the indirect hyperbilirubinemia. This simple and important diagnostic test can be performed in small laboratories.

  3. Flow cytometric determination of osmotic behaviour of animal erythrocytes toward their engineering for drug delivery

    Directory of Open Access Journals (Sweden)

    Kostić Ivana T.

    2015-01-01

    Full Text Available Despite the fact that the methods based on the osmotic properties of the cells are the most widely used for loading of drugs in human and animal erythrocytes, data related to the osmotic properties of erythrocytes derived from animal blood are scarce. This work was performed with an aim to investigate the possibility of use the flow cytometry as a tool for determination the osmotic behaviour of porcine and bovine erythrocytes, and thus facilitate the engineering of erythrocytes from animal blood to be drug carriers. The method of flow cytometry successfully provided the information about bovine and porcine erythrocyte osmotic fragility, and made the initial steps in assessment of erythrocyte shape in a large number of erythrocytes. Although this method is not able to confirm the swelling of pig erythrocytes, it indicated to the differences in pig erythrocytes that had basic hematological parameters inside and outside the reference values. In order to apply/use the porcine and bovine erythrocytes as drug carriers, the method of flow cytometry, confirming the presence of osmotically different fractions of red blood cells, indicated that various amounts of the encapsulated drug in porcine and bovine erythrocytes can be expected.

  4. Effect of Osmotic Stress on Seed Germination Indices of Nigella sativa and Silybum marianum

    Directory of Open Access Journals (Sweden)

    H Balouchi

    2012-04-01

    Full Text Available Evaluation of medicinal plants to drought and salt stress tolerance, in an attempt to plant them under drought and saline regions, is of utmost importance. Environmental stresses, especially drought and salt, reduce the global crop yields more than other factors. Selection of drought tolerant crops at germination stage, usually is, the fast and low cost method. In order to study the effect of osmotic stress on germination indices of black cumin and milk thistle, an experiment carried out in a completely randomized design with four replications at the Seed Technology Laboratoary of Yasouj University in 2008. Treatments were 0 (as control, -2.4, -4.8, -7.2 and -9.4 bar osmotic potentials created by using PEG 6000. Results showed that, decreasing of osmotic potential reduced speed of germination and its percentage, root and shoot lengths and dry matter in these two plants. Black cumin showed higher tolerance, to -4.8 bar osmotic potential, as compared to milk thistle. However, milk thistle showed higher tolerance to drought stress, up to this osmotic potential (-4.8 bar, compared to black cumin. Milk thistle had lower germination speed and percentage at higher drought stress as compared to black cumin. Generally, milk thistle showed better growth and survival than black cumin due to its higher root and shoot length and dry matter.

  5. Influence of extracellular media's ionic strength on the osmotic stability of Sahel goat erythrocytes.

    Science.gov (United States)

    Igbokwe, Nanacha Afifi; Igbokwe, Ikechukwu Onyebuchi

    2015-03-01

    Heparinised blood was exposed to osmotic lysis in hypotonic buffered saline to evaluate erythrocyte membrane stability. When K3 EDTA blood was used, it added more to the ionic content of blood than heparin. The influence of suspending media's ionic strength on the osmotic stability of Sahel goat erythrocytes was investigated by replacing the ionic saline with non-ionic saccharide (sucrose or glucose) and assessing the effect of using EDTA blood instead of heparinised blood. The erythrocyte osmotic fragility curve in saline was hyperbolic even when the ionic concentration was reduced by 50% with saccharides. Haemolysis was higher with EDTA than heparinised blood at saline concentrations of 90 and 150-180 mosmol/L. The fragility curve was sigmoidal and shifted to the left when saline was completely substituted with a saccharide. The non-ionic saccharides increased erythrocyte osmotic resistance linearly (r=0.88; p90% fragility; and saccharide concentrations were almost non-lytic at comparable saline concentrations evoking <10% haemolysis. Fragilities were neither affected by period (30-60 min) of incubation nor the type of saccharide used. In this study, the variation in osmotic stability of caprine erythrocytes was linked to ionic strength of the suspending extracellular media which seemed to exert an influence through transmembrane ion fluxes and regulatory volume changes in erythrocytes.

  6. Extracellular-matrix-mediated osmotic pressure drives Vibrio cholerae biofilm expansion and cheater exclusion.

    Science.gov (United States)

    Yan, Jing; Nadell, Carey D; Stone, Howard A; Wingreen, Ned S; Bassler, Bonnie L

    2017-08-23

    Biofilms, surface-attached communities of bacteria encased in an extracellular matrix, are a major mode of bacterial life. How the material properties of the matrix contribute to biofilm growth and robustness is largely unexplored, in particular in response to environmental perturbations such as changes in osmotic pressure. Here, using Vibrio cholerae as our model organism, we show that during active cell growth, matrix production enables biofilm-dwelling bacterial cells to establish an osmotic pressure difference between the biofilm and the external environment. This pressure difference promotes biofilm expansion on nutritious surfaces by physically swelling the colony, which enhances nutrient uptake, and enables matrix-producing cells to outcompete non-matrix-producing cheaters via physical exclusion. Osmotic pressure together with crosslinking of the matrix also controls the growth of submerged biofilms and their susceptibility to invasion by planktonic cells. As the basic physicochemical principles of matrix crosslinking and osmotic swelling are universal, our findings may have implications for other biofilm-forming bacterial species.Most bacteria live in biofilms, surface-attached communities encased in an extracellular matrix. Here, Yan et al. show that matrix production in Vibrio cholerae increases the osmotic pressure within the biofilm, promoting biofilm expansion and physical exclusion of non-matrix producing cheaters.

  7. An analysis of the effects of osmotic backwashing on the seawater reverse osmosis process.

    Science.gov (United States)

    Park, JunYoung; Jeong, WooWon; Nam, JongWoo; Kim, JaeHun; Kim, JiHoon; Chon, Kangmin; Lee, Euijong; Kim, HyungSoo; Jang, Am

    2014-01-01

    Fouling control is an important consideration in the design and operation of membrane-based water treatment processes. It has been generally known that chemical cleaning is still the most common method to remove foultants and maintain the performance of reverse osmosis (RO) desalination. Regardless of the chemical membrane cleaning methods applied effectively, however, frequent chemical cleaning can shorten the membrane life. In addition, it also increases operating and maintenance costs due to the waste chemical disposal. As an alternative, osmotic backwashing can be applied to RO membranes by diluting the concentration polarization (CP) layer. In this study, the effects of osmotic backwashing were analysed under different total dissolved salts (TDSs) and backwashing conditions, and the parameters of the osmotic backwashing were evaluated. The results of the analysis based on the properties of the organic matters found in raw water showed that the cleaning efficiency in respect to the fouling by hydrophilic organic matters was the greatest. Osmotic backwashing was carried out by changing the TDS of the permeate. As a result, the backwashing volume decreased with time due to the CP of the permeate and the backwashing volume. The difference in the osmotic pressure between the raw water and the permeate (Delta pi) also decreased as time passed. It was confirmed that when the temperature of the effluent was high, both the cleaning efficiency and the backwashing volume, which inpours at the same time, increased. When the circulation flow of the effluent was high, both the cleaning efficiency and the backwashing volume increased.

  8. Osmotic and apparent molar properties of binary mixtures alcohol + 1-butyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid

    International Nuclear Information System (INIS)

    González, Emilio J.; Calvar, Noelia; Domínguez, Ángeles; Macedo, Eugénia A.

    2013-01-01

    Highlights: ► Osmotic and physical properties of binary mixtures {alcohol + [BMim][TfO]} were measured. ► From experimental data, apparent molar properties and osmotic coefficients were calculated. ► The apparent properties were fitted using a Redlich–Meyer type equation. ► The osmotic coefficients were correlated using the Extended Pitzer model. -- Abstract: In this work, physical properties (densities and speeds of sound) for the binary systems {1-propanol, or 2-propanol, or 1-butanol, or 2-butanol, or 1-pentanol + 1-butyl-3-methylimidazolium trifluoromethanesulfonate} were experimentally measured from T = (293.15 to 323.15) K and at atmospheric pressure. These data were used to calculate the apparent molar volume and apparent molar isentropic compression which were fitted to a Redlich–Meyer type equation. This fit was used to obtain the corresponding apparent molar properties at infinite dilution. On the other hand, the osmotic and activity coefficients and vapor pressures of these binary mixtures were also determined at T = 323.15 K using the vapor pressure osmometry technique. The Extended Pitzer model of Archer was employed to correlate the experimental osmotic coefficients. From the parameters obtained in the correlation, the mean molal activity coefficients and the excess Gibbs free energy for the studied mixtures were calculated

  9. Osmotic coefficients and apparent molar volumes of 1-hexyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid in alcohols

    International Nuclear Information System (INIS)

    González, Emilio J.; Calvar, Noelia; Macedo, Eugénia A.

    2014-01-01

    Highlights: • Physical and osmotic properties of [HMim][TfO] in alcohols are reported. • Apparent molar properties and osmotic coefficients were obtained. • Apparent molar volumes were fitted using a Redlich–Meyer type equation. • The osmotic coefficients were modeled with the Extended Pitzer and the MNRTL models. -- Abstract: In this work, density for the binary mixtures of 1-hexyl-3-methylimidazolium trifluoromethanesulfonate in alcohols (1-propanol, or 2-propanol, or 1-butanol, or 2-butanol, or 1-pentanol) was measured at T = 323.15 K and atmospheric pressure. From this property, the corresponding apparent molar volumes were calculated and fitted to a Redlich–Meyer type equation. For these mixtures, the osmotic and activity coefficients, and vapor pressures of these binary systems were also determined at the same temperature using the vapor pressure osmometry technique. The experimental osmotic coefficients were modeled by the Extended Pitzer model of Archer. The parameters obtained in this correlation were used to calculate the mean molal activity coefficients and the excess Gibbs free energy for the studied mixtures

  10. Increased osmotic sensitivity for antidiuretic response in chronic chagas' disease

    Directory of Open Access Journals (Sweden)

    Joel Paulo Russomano Veiga

    1985-06-01

    Full Text Available The osmotic threshold for attaining the antidiuretic response to hypertonic saline infusion and Progressive dehydration was studied in 31 patients with the chronic form of Chagas' disease and 16 control patients. The chagasic patients exhibited enhanced osmoticsensitivity to the antidiuretic response. This was demonstrated by lower values of the increments in plasma osmolarity sufficient to induce a significant fall in water clearance, without alterations in the osmolar clearance or creatinine excretion. The time needed to attain the antidiuretic response was shorterfor chagasics in relation to normal subjects. The results suggest the existence of a disturbance in the fine control of osmoregulation in the chagasic patients. They are interpreted to be a consequence of the denervation in hypothalamic or extrahypothalamic areas that regulate the secretion of vasopressin in chronic Chagas' disease.O limiar de sensibilidade osmótíca para obtenção de resposta antídiurética foi avaliado em 31 pacientes com a forma crônica da moléstia de Chagas, através de infusão de salina hipertônica ou desidratação. Os resultados, quando comparados com os obtidos em 16 pacientes-controle, mostram uma sensibilidade osmótíca aumentada para os chagásicos, dados os menores valores do incremento na osmolaridade plasmática, suficiente para induzir uma queda significativa na depuração de água livre, sem alterações na depuração osmolar ou na excreção de creatínina. Também, o tempo necessário para atingir a antídiurese foi mais curto para os chagásicos do que para os controles. Os resultados sugerem a existência de um distúrbio na osmorregulação, nos pacientes chagásicos, caracterizado por uma sensibilidade osmótíca aumentada dos osmorreceptores para liberação da vasopressina. Estes dados interpretam-se como conseqüente à desnervação em áreas hipotalâmicas ou extra-hipotalâmicas, relacionadas com a secreção do horm

  11. 30th International Symposium on Shock Waves

    CERN Document Server

    Sadot, Oren; Igra, Ozer

    2017-01-01

    These proceedings collect the papers presented at the 30th International Symposium on Shock Waves (ISSW30), which was held in Tel-Aviv Israel from July 19 to July 24, 2015. The Symposium was organized by Ortra Ltd. The ISSW30 focused on the state of knowledge of the following areas: Nozzle Flow, Supersonic and Hypersonic Flows with Shocks, Supersonic Jets, Chemical Kinetics, Chemical Reacting Flows, Detonation, Combustion, Ignition, Shock Wave Reflection and Interaction, Shock Wave Interaction with Obstacles, Shock Wave Interaction with Porous Media, Shock Wave Interaction with Granular Media, Shock Wave Interaction with Dusty Media, Plasma, Magnetohyrdrodynamics, Re-entry to Earth Atmosphere, Shock Waves in Rarefied Gases, Shock Waves in Condensed Matter (Solids and Liquids), Shock Waves in Dense Gases, Shock Wave Focusing, Richtmyer-Meshkov Instability, Shock Boundary Layer Interaction, Multiphase Flow, Blast Waves, Facilities, Flow Visualization, and Numerical Methods. The two volumes serve as a reference ...

  12. Micriamoeba tesseris nov. gen. nov. sp.: a new taxon of free-living small-sized Amoebae non-permissive to virulent Legionellae.

    Science.gov (United States)

    Atlan, Danièle; Coupat-Goutaland, Bénédicte; Risler, Arnaud; Reyrolle, Monique; Souchon, Maud; Briolay, Jérôme; Jarraud, Sophie; Doublet, Patricia; Pélandakis, Michel

    2012-11-01

    Investigation of soil amoebae in 11 cooling towers allowed us to isolate a major unknown small-sized amoeba population (SZA). However, SZA did not appear to be specific to cooling tower ecosystems since they are also a major amoeba population found in muds isolated from different points of a water treatment plant. The SSU-rDNA sequences from SZA strains did not match any known database sequences, suggesting that SZA constitutes a new amoeba taxon. We isolated and further described one of the SZA that we named Micriamoeba tesseris. The phylogenetic analyses showed that Micriamoeba tesseris belongs to the Amebozoa and branched together with genus Echinamoeba+Vermamoeba vermiformis. Phylogenetic analyses within the Micriamoeba group distinguished different subgroups of Micriamoeba strains according to their origin, i.e. cooling tower or mud. Although Micriamoeba are able to feed on viable E. coli cells, they do not uptake virulent Legionella pneumophila strains, thus enabling them to avoid infection by Legionella. Consequently, Micriamoeba is not directly involved in L. pneumophila multiplication. However, an indirect role of Micriamoeba in Legionella risk is discussed. Copyright © 2012 Elsevier GmbH. All rights reserved.

  13. First Evidence for Diploidy and Genetic Recombination in Free-Living Amoebae of the Genus Naegleria on the Basis of Electrophoretic Variation

    OpenAIRE

    Cariou, Marie Louise; Pernin, Pierre

    1987-01-01

    Electrophoretic variation for 15 enzyme-coding genes was studied in various Naegleria (Rhizopoda, Vahlkampfiidae) species. The occurrence of complex banding patterns provided the first evidence of a diploid structure of the genome of these amoebae. The putative loci identified were found not to be linked and the genotypic distribution suggested chromosomal recombination for one species (Naegleria lovaniensis).

  14. First evidence for diploidy and genetic recombination in free-living amoebae of the genus naegleria on the basis of electrophoretic variation.

    Science.gov (United States)

    Cariou, M L; Pernin, P

    1987-02-01

    Electrophoretic variation for 15 enzyme-coding genes was studied in various Naegleria (Rhizopoda, Vahlkampfiidae) species. The occurrence of complex banding patterns provided the first evidence of a diploid structure of the genome of these amoebae. The putative loci identified were found not to be linked and the genotypic distribution suggested chromosomal recombination for one species (Naegleria lovaniensis).

  15. Isolamento de amebas de vida livre a partir de água mineral engarrafada Isolation of free-living amoebae from bottled mineral water

    Directory of Open Access Journals (Sweden)

    Homero Coutinho Salazar

    1982-10-01

    Full Text Available Foram isoladas amebas dos gêneros Vahlkampfia, Glaeseria, Acanthamoeba, Filamoeba, Amoeba, Platyamoeba e Hartmanella de dez diferentes marcas de água mineral engarrafadas, servidas no Rio de Janeiro, RJ (Brasil. Somente uma das marcas foi negativa para protozoários, enquanto que de todas as outras foram isoladas amebas de vida livre. O significado desses resultados é discutido como um indicador de qualidade da água mineral usada comercialmente, destacando-se o fato de que alguns desses microorganismos são potencialmente patogênicos.Amoebae of the genera Vahlkampfia, Glaeseria, Acanthamoeba, Filamoeba, Amoeba, Platyamoeba and Hartmanella were isolated from ten different brands of bottled mineral water used in Rio de Janeiro. Of these brands, only one was negative after an incubation period of twenty days, while the others were all positive for free living amoebae. The results are discussed as an indicator of the quality of commercially used mineral water and it is stressed that some of these microorganisms are potentially pathogenic.

  16. Electric Shock Injuries in Children

    Science.gov (United States)

    ... Español Text Size Email Print Share Electric Shock Injuries in Children Page Content ​When the human body comes into ... can cause anything from minor discomfort to serious injury (even death). Young children, particularly toddlers, experience electric shock most often when ...

  17. Shock wave treatment in medicine

    Indian Academy of Sciences (India)

    Unknown

    to open surgery, the cost of the ESWT is very reasonable. But nevertheless it is necessary to improve the basic un ... In second group, shock waves are used to measure distances because of the low energy loss over large distances ... pared to a piezoelectric hydrophone. The rise time of an electrohydraulic generated shock ...

  18. Molecular diagnostics of interstellar shocks

    Science.gov (United States)

    Hartquist, T. W.; Dalgarno, A.; Oppenheimer, M.

    1980-01-01

    The chemistry of molecules in shocked regions of the interstellar gas is considered and calculations are carried out for a region subjected to a shock at a velocity of 8 km/sec. Substantial enhancements are predicted in the concentrations of the molecules H2S, SO, and SiO compared to those anticipated in cold interstellar clouds.

  19. Floating shock fitting via Lagrangian adaptive meshes

    Science.gov (United States)

    Vanrosendale, John

    1995-01-01

    In recent work we have formulated a new approach to compressible flow simulation, combining the advantages of shock-fitting and shock-capturing. Using a cell-centered on Roe scheme discretization on unstructured meshes, we warp the mesh while marching to steady state, so that mesh edges align with shocks and other discontinuities. This new algorithm, the Shock-fitting Lagrangian Adaptive Method (SLAM), is, in effect, a reliable shock-capturing algorithm which yields shock-fitted accuracy at convergence.

  20. Oscillating nonlinear acoustic shock waves

    DEFF Research Database (Denmark)

    Gaididei, Yuri; Rasmussen, Anders Rønne; Christiansen, Peter Leth

    2016-01-01

    We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show...... that at resonance a stationary state arise consisting of multiple oscillating shock waves. Off resonance driving leads to a nearly linear oscillating ground state but superimposed by bursts of a fast oscillating shock wave. Based on a travelling wave ansatz for the fluid velocity potential with an added 2'nd order...... polynomial in the space and time variables, we find analytical approximations to the observed single shock waves in an infinitely long tube. Using perturbation theory for the driven acoustic system approximative analytical solutions for the off resonant case are determined....