Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Endothelin role in the orthostatic stress Papel da endotelina no estresse ortostático  [cached]
Luciana Cristina Fosco,Marli Cardoso Martins Pinge
Semina : Ciências Biológicas e da Saúde , 2008,
Abstract: Orthostasis adoption causes hemodynamic changes. Hydrostatic opposition to the venous return, venous return reduction and cardiac output decrease act as stimuli and generate compensatory mechanisms. The central nervous system adjusts the autonomic sympathetic and parasympathetic activity. The autonomous nervous system causes a tonic and reflexive influence on the main variables of the cardiovascular system and, together with hormonal components, extends the adaptation capacity in face of postural changes. Any difficulties in this compensatory mechanism that prevents it from functioning properly may result in hypotension response failure, what, on its turn, can lead to cerebral hypoperfusion, hypoxia and loss of consciousness. Blood pressure maintenance at normal levels is important for the internal medium homeosthasis. Baroreflex plays an important role in the cardiovascular control in the short-term in the adaptation of the orthostatic stress, preventing excessive blood pressure alterations. During the orthostatic stress, neuroendocrinal changes also occur as alteration in endothelin plasma levels. Endothelin, a peptide formed by 21 amino acids, shows a powerful vasoconstrictor action. It also demonstrates that its levels in the blood are increased in response to an orthostatic stress. However, although endothelin-1 levels increase in response to an acute postural stress, its role in cardiovascular homeosthasis and its relation in the release of other hormones are still controversial and quite unknown in humans in vivo. A ado o da ortostase promove altera es hemodinamicas. A oposi o hidrostática ao retorno venoso, a redu o do retorno venoso e a diminui o do débito cardíaco atua como estímulos e geram mecanismos compensatórios. O sistema nervoso central ajusta a atividade auton mica simpática e parassimpática. O sistema nervoso aut nomo influencia t nica e reflexamente as principais variáveis do sistema cardiovascular e, juntamente com componentes hormonais, amplia a capacidade de adapta o frente a mudan as posturais. Qualquer dificuldade nesse mecanismo compensatório que impe a seu funcionamento adequado pode resultar em falha da resposta com hipotens o, que, por sua vez, pode levar à hipoperfus o cerebral, hipóxia e perda de consciência. A manuten o da press o arterial em níveis normais é importante para a homeostasia do meio interno. O barorreflexo desempenha papel fundamental no controle cardiovascular a curto-prazo na adapta o ao estresse ortostático, e prevendo excessivas flutua es da press o arterial. Durante o estresse ortostático, tamb
Ambulatory Pessary Trial Unmasks Occult Stress Urinary Incontinence  [PDF]
Bilal Chughtai,Sara Spettel,Jonathan Kurman,Elise De
Obstetrics and Gynecology International , 2012, DOI: 10.1155/2012/392027
Abstract: Objective. We evaluated the use of a one-week ambulatory pessary trial in predicting patients' postoperative outcomes for occult stress incontinence. Methods. Patients with anterior vaginal wall prolapse were offered a pessary trial to predict response to reconstruction. We performed a retrospective review of 4 years of cases. All patients underwent a detailed evaluation including videourodynamics with and without pessary reduction. Results. Twenty-six patients completed the 1-week pessary trial. Ten (38%) women showing no evidence of stress urinary incontinence (SUI) underwent surgical repair of prolapse without anti-incontinence procedure. None of these patients had SUI postoperatively. Sixteen women (61%) had occult stress urinary incontinence on evaluation and underwent concurrent sling procedure. Three (19%) of these patients were identified by the pessary trial alone. Twenty-five of the 26 patients were without clinical stress incontinence at a mean follow up of 12 months (range 4–37 months). The pessary trial correctly predicted persistent urgency in six patients and persistent frequency in five. No patients with SUI or persistent voiding difficult were missed in a pessary trial. Conclusion. An ambulatory pessary trial is an effective, easy, and inexpensive method to approximate anatomic results achieved by surgery under real-life conditions. In our series, 20% of patients with occult SUI were identified by pessary trial alone. 1. Introduction Each year, approximately 200,000 women undergo surgical treatment for pelvic organ prolapse (POP) in the United States [1]. Of these women, approximately 21% included urinary incontinence procedures, for an annual cost of greater than $1 billion for surgical repair of prolapse [2]. The demand for POP repair is expected to increase as the U.S. population ages and life expectancies increase. The central question in the preoperative evaluation of a patient with POP is to estimate functional outcome once the anatomy is corrected. It is well documented that stress-continent women with advanced POP may develop stress urinary incontinence (SUI) following prolapse reduction [3, 4]. It is thought that correction of the anatomy will unkink or decrease resistance to the urethra, thereby unmasking intrinsic sphincteric deficiency. Regardless of objective outcome of prolapse repair, patient satisfaction with surgery is highly correlated with patient expectations preoperatively [5]. There are no clear guidelines regarding concurrent anti-incontinence procedures during surgical prolapse repair. Some surgeons place a sling
The Effects of Stress Tensor Fluctuations upon Focusing  [PDF]
J. Borgman,L. H. Ford
Physics , 2003, DOI: 10.1103/PhysRevD.70.064032
Abstract: We treat the gravitational effects of quantum stress tensor fluctuations. An operational approach is adopted in which these fluctuations produce fluctuations in the focusing of a bundle of geodesics. This can be calculated explicitly using the Raychaudhuri equation as a Langevin equation. The physical manifestation of these fluctuations are angular blurring and luminosity fluctuations of the images of distant sources. We give explicit results for the case of a scalar field on a flat background in a thermal state.
Environmental Influences Cause Stress on the Use of Computer
I Ketut Wijaya
International Journal of Public Health Science , 2012, DOI: 10.11591/ijphs.v1i1.419
Abstract: Working with a computer over a period long enough to be done. Computer is the best medium currently in appearance and in the way of working, because the computer can assist in completing the work in a more rapid, efficient and very easy to use. With the convenience offered by the computer, almost all the work can be done with computer. Computers are a necessity in supporting work and communication tool that is quite reliable. The computer is useful in life, but can also cause problems on users, the computer can issue radiation that affects the condition of the user as well as ignorance in using computers can cause Repetitive Strain Injury (RSI). Besides, the use of computers can lead to stress as a result of incomprehension in determining the condition of the environment on room. To be able to know the stress resulting from the use of computer, conducted research with a sample of 30 people at Udayana University Computer Science students with a design the same subject. Data analysis was performed with SPSS 13.00 and differences in the data before and after the redesigned (improvement), that do use the test independent sample t-test (t test group), at the level of significance of 5%. After a redesigned (improvement) on the environmental temperature is obtained decrease in the standard cold temperatures of Indonesia work of 28.00 C to 25.83 C, occupational stress decreased from 86% to 42%, and improve learning outcomes from 59.6% to 98.1%.. Thus It can be concluded that due to improvements made agains environmentally ergonomic standards can reduce the stress of work. Keywords: Computers; Stress.
Expression of endothelin in organ-cultured artery under low shear stress

LIU Bo,ZHOU Jin,LIU Yan-chun,Teng Hai-yin,Jiang Zong-lai,

生物物理学报 , 2005,
Abstract: The biological effect of shear strees on intact artery and the change of Endothelin (ET) during the stress-induced vascular remodeling was studied. The common carotid arteries of pigs were cultured with a artery organ-culture system under different shear stress, 0.5 and 2 Pa respectively, 1.33×10-4 Pa of pressure and stable flow in vitro. Cultured for 2, 4, 6, 8, 10, 12, 14, 16 and 18 h, the content of ET in the perfusate was examined with radio-immunity method, and the data were described by Logistic equation. The secretion velocity of ET didn't change obviously in S20 group, while in S5 group it rised evidently at the first 12 h and then descend to a stable level which was higher than S20 group all the time. The secretion and expression of ET rised under low shear stress. It may play an important role in vascular remodeling induced by low shear stress.
Liver sinusoidal endothelial cell modulation upon resection and shear stress in vitro
Filip Braet, Maria Shleper, Melia Paizi, Sergey Brodsky, Natalia Kopeiko, Nitzan Resnick, Gadi Spira
Comparative Hepatology , 2004, DOI: 10.1186/1476-5926-3-7
Abstract: Following partial hepatectomy blood flow-to-liver mass ratio reached maximal values 24 hrs post resection. Concomitantly, large fenestrae (gaps) were noted. Exposure of liver sinusoidal endothelial cells, in vitro, to physiological laminar shear stress forces was associated with translocation of vascular endothelial cell growth factor receptor-2 (VEGFR-2) and neuropilin-1 from perinuclear and faint cytoplasmic distribution to plasma membrane and cytoskeletal localization. Under these conditions, VEGFR-2 co-stains with VE-cadherin. Unlike VEGFR-2, the nuclear localization of VEGFR-1 was not affected by shear stress. Quantification of the above receptors showed a significant increase in VEGFR-1, VEGFR-2 and neuropilin-1 mRNA following shear stress.Our data suggest a possible relation between elevated blood flow associated with partial hepatectomy and the early events occurring thereby.Following partial hepatectomy (PHx) the remaining liver is transfused by normal blood volume, thereby exposing liver sinusoidal endothelial cells (LECs) to excess hemodynamic forces. These forces have been noted as an early event leading to liver restoration in rats [1-3]; however, the idea that quality of the blood rather than quantity has been the accepted dogma [4,5]. Based on time-scale events, shear stress inflicted on liver cells precedes the expression of factors some of which are expressed within minutes. Studies conducted in recent years indicate that shear stress induced NO leads to the expression of genes participating in liver regeneration including c-fos [6-8]. There is evidence demonstrating that increase of c-fos in PHx or portal branch ligation models is inhibited by N-nitro-L-arginine methyl ester, which blocks NO synthase [8]. The present study was undertaken to examine the molecular and ultrastructural effects of hemodynamic forces on LECs. We have chosen to focus on vascular endothelial cell growth factor (VEGF) receptors (VEGFRs), as these are present on endothelial
Pre-Disposition and Epigenetics Govern Variation in Bacterial Survival upon Stress  [PDF]
Ming Ni,Antoine L. Decrulle equal contributor,Fanette Fontaine equal contributor,Alice Demarez,Francois Taddei,Ariel B. Lindner
PLOS Genetics , 2012, DOI: 10.1371/journal.pgen.1003148
Abstract: Bacteria suffer various stresses in their unpredictable environment. In response, clonal populations may exhibit cell-to-cell variation, hypothetically to maximize their survival. The origins, propagation, and consequences of this variability remain poorly understood. Variability persists through cell division events, yet detailed lineage information for individual stress-response phenotypes is scarce. This work combines time-lapse microscopy and microfluidics to uniformly manipulate the environmental changes experienced by clonal bacteria. We quantify the growth rates and RpoH-driven heat-shock responses of individual Escherichia coli within their lineage context, stressed by low streptomycin concentrations. We observe an increased variation in phenotypes, as different as survival from death, that can be traced to asymmetric division events occurring prior to stress induction. Epigenetic inheritance contributes to the propagation of the observed phenotypic variation, resulting in three-fold increase of the RpoH-driven expression autocorrelation time following stress induction. We propose that the increased permeability of streptomycin-stressed cells serves as a positive feedback loop underlying this epigenetic effect. Our results suggest that stochasticity, pre-disposition, and epigenetic effects are at the source of stress-induced variability. Unlike in a bet-hedging strategy, we observe that cells with a higher investment in maintenance, measured as the basal RpoH transcriptional activity prior to antibiotic treatment, are more likely to give rise to stressed, frail progeny.
Aspergillus oryzae AoSO Is a Novel Component of Stress Granules upon Heat Stress in Filamentous Fungi  [PDF]
Hsiang-Ting Huang, Jun-ichi Maruyama, Katsuhiko Kitamoto
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0072209
Abstract: Stress granules are a type of cytoplasmic messenger ribonucleoprotein (mRNP) granule formed in response to the inhibition of translation initiation, which typically occurs when cells are exposed to stress. Stress granules are conserved in eukaryotes; however, in filamentous fungi, including Aspergillus oryzae, stress granules have not yet been defined. For this reason, here we investigated the formation and localization of stress granules in A. oryzae cells exposed to various stresses using an EGFP fusion protein of AoPab1, a homolog of Saccharomyces cerevisiae Pab1p, as a stress granule marker. Localization analysis showed that AoPab1 was evenly distributed throughout the cytoplasm under normal growth conditions, and accumulated as cytoplasmic foci mainly at the hyphal tip in response to stress. AoSO, a homolog of Neurospora crassa SO, which is necessary for hyphal fusion, colocalized with stress granules in cells exposed to heat stress. The formation of cytoplasmic foci of AoSO was blocked by treatment with cycloheximide, a known inhibitor of stress granule formation. Deletion of the Aoso gene had effects on the formation and localization of stress granules in response to heat stress. Our results suggest that AoSO is a novel component of stress granules specific to filamentous fungi. The authors would specially like to thank Hiroyuki Nakano and Kei Saeki for generously providing experimental and insightful opinions.
Influences of Annealing on Residual Stress and Structure of HfO2 Films
SHEN Yan-Ming,SHAO Shu-Ying,DENG Zhen-Xia,HE Hong-Bo,SHAOJian-Da,FAN Zheng-Xiu,

中国物理快报 , 2007,
Abstract: HfO2 films are deposited on BK7 glass substrates by electron beam evaporation. The influences of annealing between 100°C and 400°C on residual stresses and structures of HfO2 films are studied. It is found that little differences of spectra, residual stresses and structures are obtained after annealing at lower temperatures. After annealing at higher temperatures, the spectra shift to short wavelength, the residual stress increases with the increasing annealing temperature. At the same time, the crystallite size increases and interplanar distance decreases. The variations of optical spectra and residual stress correspond to the evolutions of structures induced by annealing.
Depression, Anxiety Levels and Coping Strategies with Stress in Continuous Ambulatory Peritoneal Dialysis (CAPD) and Hemodialysis (HD) Patients in a University Hospital  [PDF]
Selma ?ET?NKAYA,Naim NUR,Adnan AYVAZ,Deniz ?ZDEM?R
N?ropsikiyatri Ar?ivi , 2008,
Abstract: Objective: This study is aimed to evaluate depression and anxiety levels and coping strategies with stress in continuous ambulatory peritoneal dialysis (CAPD) and hemodialysis (HD) patients.Method: Study which was planned as a descriptive cross-sectional research has been made among patients who were under treatment with CAPD or HD for chronic renal failure in Cumhuriyet University Hospital in 01-31 August 2007. Questions were asked to determine the demographic profile, tobacco and alcohol use patterns and psychological status of the patients. Beck Depression Inventory and State-Trait Anxiety Inventory I-II (STAI-I, STAI-II) and Coping Strategies With Stress Inventory (COPE) were used for psychological evaluation.Results: Depression rate was 33.3% in CAPD patients and 61.3% in HD patients. Beck Depression Inventory and State-Trait Anxiety Inventory I-II (STAI-I, STAI-II) scores were 14.1±8.4, 39.3±4.7, 47.6±5.1 and 19.9±9.9, 41.0±3.7, 49.5±6.2 in CAPD and HD patients respectively. CAPD patients’ depression scores were significantly lower than HD patients’ (p<0.05) whereas there was no significant difference between Beck Depression Inventory and State-Trait Anxiety Inventory scores (p>0.05). In both groups the most frequently used coping strategy was religious coping followed by positive reinterpretation and development methods. The only significant difference between groups were in “to laugh it off” and “not to worry about it” strategies. Conclusion: Depression and anxiety appeared frequently in all dialysis patients, but depression was more frequent in HD patients. Therefore it is considered necessary for dialysis patients (CAPD and HD) to be under regular psychiatric evaluation. (Archives of Neuropsychiatry 2008; 45: 78-84)
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.