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991.
992.
Proper assessment of environmental resistance of animals is critical for the ability of researchers to understand how variation in environmental conditions influence population and species abundance. This is also the case for studies of upper thermal limits in insects, where researchers studying animals under laboratory conditions must select appropriate methodology on which conclusions can be drawn. Ideally these methods should precisely estimate the trait of interest and also be biological meaningful. In an attempt to develop such tests it has been proposed that thermal ramping assays are useful assays for small insects because they incorporate an ecologically relevant gradual temperature change. However, recent model-based papers have suggested that estimates of thermal resistance may be strongly confounded by simultaneous starvation and dehydration stress. In the present study we empirically test these model predictions using two sets of independent experiments. We clearly demonstrate that results from ramping assays of small insects (Drosophila melanogaster) are not compromised by starvation- or dehydration-stress. Firstly we show that the mild disturbance of water and energy balance of D. melanogaster experienced during the ramping tests does not confound heat tolerance estimates. Secondly we show that flies pre-exposed to starvation and dehydration have "normal" heat tolerance and that resistance to heat stress is independent of the energetic and water status of the flies. On the basis of our results we discuss the assumptions used in recent model papers and present arguments as to why the ramping assay is both a valid and ecologically relevant way to measure thermal resistance in insects. 相似文献
993.
Background
Previous studies indicate multiple influences on the overall health of HIV-infected persons; however, few assess and rank longitudinal changes in social and structural barriers that are disproportionately found in impoverished populations. We empirically ranked factors that longitudinally impact the overall health status of HIV-infected homeless and unstably housed men.Methods and Findings
Between 2002 and 2008, a cohort of 288 HIV+ homeless and unstably housed men was recruited and followed over time. The population was 60% non-Caucasian and the median age was 41 years; 67% of study participants reported recent drug use and 20% reported recent homelessness. At baseline, the median CD4 cell count was 349 cells/µl and 18% of eligible persons (CD4<350) took antiretroviral therapy (ART). Marginal structural models were used to estimate the population-level effects of behavioral, social, and structural factors on overall physical and mental health status (measured by the SF-36), and targeted variable importance (tVIM) was used to empirically rank factors by their influence. After adjusting for confounding, and in order of their influence, the three factors with the strongest negative effects on physical health were unmet subsistence needs, Caucasian race, and no reported source of instrumental support. The three factors with the strongest negative effects on mental health were unmet subsistence needs, not having a close friend/confidant, and drug use. ART adherence >90% ranked 5th for its positive influence on mental health, and viral load ranked 4th for its negative influence on physical health.Conclusions
The inability to meet food, hygiene, and housing needs was the most powerful predictor of poor physical and mental health among homeless and unstably housed HIV-infected men in an urban setting. Impoverished persons will not fully benefit from progress in HIV medicine until these barriers are overcome, a situation that is likely to continue fueling the US HIV epidemic. 相似文献994.
Jeremy Miller Torsten Dikow Donat Agosti Guido Sautter Terry Catapano Lyubomir Penev Zhi-Qiang Zhang Dean Pentcheff Richard Pyle Stan Blum Cynthia Parr Chris Freeland Tom Garnett Linda S Ford Burgert Muller Leo Smith Ginger Strader Teodor Georgiev Laurence Bénichou 《BMC biology》2012,10(1):1-5
In the ubiquitin-proteasome system, a subset of ubiquitylated proteins requires the AAA+ ATPase p97 (also known as VCP or Cdc48) for extraction from membranes or protein complexes before delivery to the proteasome for degradation. Diverse ubiquitin adapters are known to link p97 to its client proteins, but two recent papers on the adapter protein UBXD7, including one by Bandau et al. in BMC Biology, suggest that rather than simply linking p97 to ubiquitylated proteins, this adapter may be essential to coordinate ubiquitylation and p97-mediated extraction of the proteasome substrate. These findings add to growing indications of richly diverse roles of adapters in p97-mediated signaling functions. See research article: http://www.biomedcentral.com/1741-7007/10/36 相似文献
995.
Sebastian J. Theobald Christoph Kreer Sahamoddin Khailaie Agnes Bonifacius Britta Eiz-Vesper Constanca Figueiredo Michael Mach Marija Backovic Matthias Ballmaier Johannes Koenig Henning Olbrich Andreas Schneider Valery Volk Simon Danisch Lutz Gieselmann Meryem Seda Ercanoglu Martin Messerle Constantin von Kaisenberg Torsten Witte Frank Klawonn Michael Meyer-Hermann Florian Klein Renata Stripecke 《PLoS pathogens》2021,17(3)
996.
Juan M. Bolivar Tanja Consolati Torsten Mayr Bernd Nidetzky 《Biotechnology and bioengineering》2013,110(8):2086-2095
Enzymatic O2‐dependent oxidations are receiving increased attention for use in fine chemicals synthesis. Solid supported oxidation catalysts often show poor efficiency due to pronounced O2 diffusion restriction. Internal O2 supply therefore constitutes a key parameter for optimizing the enzyme immobilization. We herein describe an optical sensing method for quantitation of space‐averaged intraparticle O2 concentrations in porous Sepabeads carriers. The method applies phosphorescence lifetime measurements on Sepabeads labeled with an O2 sensitive indicator dye. Using glucose oxidase immobilized at different loadings (0.005–12 mg/g) on labeled Sepabeads, we analyzed in real time during the enzymatic reaction the formation of O2 concentration differences between bulk liquid and the intraparticle environment. We show that the O2 gradient at apparent steady state increased with increasing enzyme loading, so that O2 eventually became totally depleted from inside the highly loaded carriers. We also show that the residual intraparticle O2 concentration was correlated with the catalytic effectiveness factor (η) of the enzyme immobilizate used, thus providing a direct measure of the magnitude of O2 diffusion limitation. Once corrected for diffusional effect, η was no longer dependent on enzyme loading and its constant value now described the intrinsic activity of immobilized glucose oxidase. Three common procedures of enzyme immobilization, involving adsorption, cross‐linking, and covalent attachment, are shown to differ widely concerning the obtained intrinsic activity. Therefore, intraparticle O2 concentration data enable distinction between diffusional restriction and activity loss as the two principal factors limiting the effectiveness of immobilized O2 dependent enzymes, and thus they inform rational design of an optimally active oxidation biocatalyst on solid support. Biotechnol. Bioeng. 2013; 110: 2086–2095. © 2013 Wiley Periodicals, Inc. 相似文献
997.
998.
Torsten Gunnarsson Anders Karlsson Per Hansson Göran Johnson Christer Alling Göran Odham 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1998,705(2):1428
The `pathologic' phospholipid, phosphatidylethanol (PEth), formed only in the presence of ethanol, was determined in extracts of human blood using high-performance liquid chromatography with evaporative light scattering detection (ELSD) or electrospray (ES) mass spectrometry. Separation was performed using a diol column and a normal-phase binary gradient system. Decreasing concentrations of PEth (15 to 1 nmol/ml blood) could be detected by ELSD in three male alcoholics, up to 3 weeks after the beginning of an alcohol-free period. Using ES, levels down to 100 pmol/ml blood was detected. The molecular species of PEth were similar to those of phosphatidylcholine found in the same blood sample. The method provides a rapid quantitative and qualitative determination of PEth in blood. The limits of detection were 200 pmol (≈125 ng) using ELSD and 140 fmol (≈100 pg) using ES, total amounts injected. 相似文献
999.
1000.