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John D. Fitzsimons Bill Williston Georgina Williston Lisa Brown Abdel El-Shaarawi Lenore Vandenbyllaardt Dale Honeyfeld Don Tillitt Martha Wolgamood Scott B. Brown 《Journal of Great Lakes research》2007,33(1):93-103
Alewives (Alosa pseudoharengus), the major prey fish for Lake Ontario, contain thiaminase. They are associated with development of a thiamine deficiency in salmonines which greatly increases the potential for developing an early mortality syndrome (EMS). To assess the possible effects of thiamine deficiency on salmonine reproduction we measured egg thiamine concentrations for five species of Lake Ontario salmonines. From this we estimated the proportion of families susceptible to EMS based on whether they were below the ED20, the egg thiamine concentration associated with 20% mortality due to EMS. The ED20s were 1.52, 2.63, and 2.99 nmol/g egg for Chinook salmon (Oncorhynchus tshawytscha), lake trout (Salvelinus namaycush), and coho salmon (Oncorhynchus kisutch), respectively. Based on the proportion of fish having egg thiamine concentrations falling below the ED20, the risk of developing EMS in Lake Ontario was highest for lake trout, followed by coho (O. kisutch), and Chinook salmon, with the least risk for rainbow trout (O. mykiss). For lake trout from western Lake Ontario, mean egg thiamine concentration showed significant annual variability during 1994 to 2003, when the proportion of lake trout at risk of developing EMS based on ED20 ranged between 77 and 100%. Variation in the annual mean egg thiamine concentration for western Lake Ontario lake trout was positively related (p < 0.001, r2 = 0.94) with indices of annual adult alewife biomass. While suggesting the possible involvement of density-dependent changes in alewives, the changes are small relative to egg thiamine concentrations when alewife are not part of the diet and are of insufficient magnitude to allow for natural reproduction by lake trout. 相似文献
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Rat hepatocytes in monolayer culture were utilized to determine if the decrease in glucose-6-phosphate dehydrogenase (G6PD)
activity resulting from the ingestion of fat can be mimicked by the addition of fatty acids to a chemically, hormonally defined
medium. G6PD activity in cultured hepatocytes was induced several-fold by insulin. Dexamethasone or T3 did not amplify the
insulin induction of G6PD. Glucose alone increased G6PD activity in cultured hepatocytes from fasted donors by nearly 500%.
Insulin in combination with glucose induced G6PD an additional two-fold. The increase in G6PD activity caused by glucose was
greater in hepatocytes isolated from 72 hr-fasted rats as compared to fed donor rats. Such a response was reminiscent of the
“overshoot” phenomenon in which G6PD activity is induced well above the normal level by fasting-refeeding rats a high glucose
diet. Addition of linoleate to the medium resulted in a significant suppression of insulin’s ability to induce G6PD, but linoleate
had no effect on the induction of G6PD activity by glucose alone. A shift to the right in the insulin-response curve for the
induction of G6PD also was detected for the induction of malic enzyme and acetyl-CoA carboxylase. Arachidonate (0.25 mM) was
a significantly more effective inhibitor of the insulin action than linoleate was. Apparently rat hepatocytes in monolayer
culture can be utilized as a model to investigate the molecular mechanism by which fatty acids inhibit the production of lipogenic
enzymes. In part, this mechanism of fatty acid inhibition involves desensitization of hepatocytes to the lipogenic action
of insulin. 相似文献
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Alumina membranes were prepared using a sol–gel process. Thin gel layers were grown onto porous alumina support tubes by using the permeation of water through the tube to control the rate of hydrolysis. Optimum coating conditions were found to be an ASB to 2-propanol volume ratio of 1:25, coating times between 10 and 15 s, and partial drying times between 2.5 and 3 min, depending on whether the water was flowing in the tube or stored in the tube. The coatings remained crack-free and adherent when fired to 800°C. 相似文献
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为了观察分析高密度聚乙烯(HDPE)的银纹区性能,对两种HDPE全切痕试样分别进行了速率为0.1 mm/min,0.5 mm/min,1 mm/min,5 mm/min,20 mm/min和50 mm/min的拉伸测试。基于对静态断裂过程应力-位移数据的分析处理,结果表明,HDPE的屈服应力随着拉伸速率增大;高应力时两种HDPE均存在常临界位移控制其银纹断裂;HDPE2480银纹微纤的稳定性较大,材料韧性较好。HDPE静态拉伸断面显微结构显示,HDPE2480的银纹微纤尺寸大于HDPE4801,导致两者断面弧形巢尺寸和弧形巢内粗糙度的不同。 相似文献
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Tom Schreiner Lisa Allnoch Georg Beythien Katarzyna Marek Kathrin Becker Dirk Schaudien Stephanie Stanelle-Bertram Berfin Schaumburg Nancy Mounogou Kouassi Sebastian Beck Martin Zickler Gülsah Gabriel Wolfgang Baumgrtner Federico Armando Malgorzata Ciurkiewicz 《International journal of molecular sciences》2022,23(9)
Similar to many other respiratory viruses, SARS-CoV-2 targets the ciliated cells of the respiratory epithelium and compromises mucociliary clearance, thereby facilitating spread to the lungs and paving the way for secondary infections. A detailed understanding of mechanism involved in ciliary loss and subsequent regeneration is crucial to assess the possible long-term consequences of COVID-19. The aim of this study was to characterize the sequence of histological and ultrastructural changes observed in the ciliated epithelium during and after SARS-CoV-2 infection in the golden Syrian hamster model. We show that acute infection induces a severe, transient loss of cilia, which is, at least in part, caused by cilia internalization. Internalized cilia colocalize with membrane invaginations, facilitating virus entry into the cell. Infection also results in a progressive decline in cells expressing the regulator of ciliogenesis FOXJ1, which persists beyond virus clearance and the termination of inflammatory changes. Ciliary loss triggers the mobilization of p73+ and CK14+ basal cells, which ceases after regeneration of the cilia. Although ciliation is restored after two weeks despite the lack of FOXJ1, an increased frequency of cilia with ultrastructural alterations indicative of secondary ciliary dyskinesia is observed. In summary, the work provides new insights into SARS-CoV-2 pathogenesis and expands our understanding of virally induced damage to defense mechanisms in the conducting airways. 相似文献
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Suresh Sivasubramaniam Lisa Murphy 《电子测试》2005,(9):62-65
PowerPC处理器能帮助实现快速灵活的可编程嵌入式平台设计.Virtex-4 FX平台利用集成于双PowerPC处理器的创新辅助处理器单元(APU)控制器,支持新的硬件加速应用.FX APU控制器又大大改善了软件算法的执行,提高了FPGA资源可用性.本文将介绍使用Xilinx/Ansoft 10Gbps背板设计套件确保互连性能. 相似文献
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