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排序方式: 共有650条查询结果,搜索用时 187 毫秒
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Brevetoxins are a family of ladder-framed polyether toxins produced during blooms of the marine dinoflagellate, Karenia brevis. Consumption of shellfish or finfish exposed to brevetoxins can lead to the development of neurotoxic shellfish poisoning. The toxic effects of brevetoxins are believed to be due to the activation of voltage-sensitive sodium channels in cell membranes. The traditional cytotoxicity assay for detection of brevetoxins uses the Neuro-2A cell line, which must first be treated with the neurotoxins, ouabain and veratridine, in order to become sensitive to brevetoxins. In this study, we demonstrate several drawbacks of the Neuro-2A assay, which include variability for the EC50 values for brevetoxin and non-linear triphasic dose response curves. Ouabain/veratridine-treated Neuro-2A cells do not show a typical sigmoidal dose response curve in response to brevetoxin, but rather, have a polynomial shaped curve, which makes calculating EC50 values highly variable. We describe a new fluorescence live cell imaging model, which allows for accurate calculation of cytotoxicity via nuclear staining and additional measurement of other viability parameters depending on which aspect of the cell is stained. In addition, the SJCRH30 cell line shows promise as an alternative to Neuro-2A cells for testing brevetoxins without the need for ouabain and veratridine. 相似文献
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Kim KC Reed CA Elliott DW Mueller LJ Tham F Lin L Lambert JB 《Science (New York, N.Y.)》2002,297(5582):825-827
Evidence for a three-coordinate silyl cation is provided by the crystal structure of [(Mes)3Si][H-CB11Me5Br6].C6H6 (where Mes is 2,4,6-trimethylphenyl). Free (Mes)3Si+ cations are well separated from the carborane anions and benzene solvate molecules. Ortho-methyl groups of the mesityl substituents shield the silicon atom from the close approach of nucleophiles, while remaining innocent as significant ligands themselves. The silicon center is three-coordinate and planar. The downfield 29Si nuclear magnetic resonance chemical shift in the solid state (226.7 parts per million) is almost identical to that in benzene solution and in "gas phase" calculations, indicating that three-coordination can be preserved in all phases. 相似文献
646.
Bouatia-Naji N Rocheleau G Van Lommel L Lemaire K Schuit F Cavalcanti-Proença C Marchand M Hartikainen AL Sovio U De Graeve F Rung J Vaxillaire M Tichet J Marre M Balkau B Weill J Elliott P Jarvelin MR Meyre D Polychronakos C Dina C Sladek R Froguel P 《Science (New York, N.Y.)》2008,320(5879):1085-1088
Several studies have shown that healthy individuals with fasting plasma glucose (FPG) levels at the high end of the normal range have an increased risk of mortality. To identify genetic determinants that contribute to interindividual variation in FPG, we tested 392,935 single-nucleotide polymorphisms (SNPs) in 654 normoglycemic participants for association with FPG, and we replicated the most strongly associated SNP (rs560887, P = 4 x 10(-7)) in 9353 participants. SNP rs560887 maps to intron 3 of the G6PC2 gene, which encodes glucose-6-phosphatase catalytic subunit-related protein (also known as IGRP), a protein selectively expressed in pancreatic islets. This SNP was associated with FPG (linear regression coefficient beta = -0.06 millimoles per liter per A allele, combined P = 4 x 10(-23)) and with pancreatic beta cell function (Homa-B model, combined P = 3 x 10(-13)) in three populations; however, it was not associated with type 2 diabetes risk. We speculate that G6PC2 regulates FPG by modulating the set point for glucose-stimulated insulin secretion in pancreatic beta cells. 相似文献
647.
Daniel F Kripke Jeffrey A Elliott Shawn D Youngstedt Katharine M Rex 《Journal of circadian rhythms》2007,5(1):4-13
Background
The phase of a circadian rhythm reflects where the peak and the trough occur, for example, the peak and trough of performance within the 24 h. Light exposure can shift this phase. More extensive knowledge of the human circadian phase response to light is needed to guide light treatment for shiftworkers, air travelers, and people with circadian rhythm phase disorders. This study tested the hypotheses that older adults have absent or weaker phase-shift responses to light (3000 lux), and that women's responses might differ from those of men. 相似文献648.
649.
Kelly E Helmick Mark G Papich Kent A Vliet R Avery Bennett Elliott R Jacobson 《Journal of zoo and wildlife medicine》2004,35(3):341-346
The pharmacokinetics of a long-acting oxytetracycline preparation administered i.v. and i.m. to American alligators (Alligator mississippiensis) at 10 mg/kg was determined. Plasma levels of oxytetracycline were measured using high-performance liquid chromatography, and the resulting concentration versus time curve was analyzed using compartmental modeling and noncompartmental modeling techniques for i.v. and i.m. samples, respectively. A two-compartment model best represented the i.v. data. Intravenous administration of oxytetracycline resulted in an extrapolated mean plasma concentration at time zero of 60.63 +/- 28.26 microg/ml, with average plasma drug levels of 2.82 +/- 0.71 microg/ml at the end of the 192-hr sampling period. Plasma volume of distribution for i.v. oxytetracycline was 0.20 +/- 0.09 L/kg, with a harmonic mean elimination half-life of 15.15 hr and mean total body clearance rate of 0.007 +/- 0.002 L/hr/kg. Intramuscular administration of oxytetracycline achieved a mean peak plasma concentration of 6.85 +/- 1.96 microg/ml at 1 hr after administration, with average plasma drug levels of 4.96 +/- 1.97 microg/ml at the end of the 192-hr sampling period. The harmonic mean terminal elimination half-life for i.m. oxytetracycline was 131.23 hr. Based on the results of this study, long-acting preparations of oxytetracycline administered parenterally to American alligators at 10 mg/kg q 5 days is expected to maintain plasma concentrations above the minimum inhibitory concentration of 4.0 microg/ml for susceptible organisms. 相似文献
650.
Dirk Hendrik Nicolaas van den Broek Rebecca F. Geddes Nicola S. Ltter YuMei Chang Jonathan Elliott Rosanne E. Jepson 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2022,36(4):1312
BackgroundHypercalcemia is associated with chronic kidney disease (CKD) in cats, but studies assessing the physiologically relevant ionized calcium fraction are lacking.ObjectivesTo describe the prevalence and incidence rate of ionized hypercalcemia, and to explore predictor variables to identify cats at risk of ionized hypercalcemia in a cohort of cats diagnosed with azotemic CKD.AnimalsOne hundred sixty‐four client‐owned cats with azotemic CKD.MethodsVariables independently associated with ionized hypercalcemia at diagnosis of azotemic CKD were explored by binary logistic regression. Cats that were normocalcemic at diagnosis of azotemic CKD were followed over a 12‐month period or until ionized hypercalcemia occurred and baseline predictor variables for ionized hypercalcemia explored using Cox proportional hazards and receiver operating characteristic curve analysis.ResultsIonized hypercalcemia (median, 1.41 mmol/L; range, 1.38‐1.68) was observed in 33/164 (20%) cats at diagnosis of azotemic CKD and was associated with male sex, higher plasma total calcium and potassium concentrations, and lower plasma parathyroid hormone concentrations. Twenty‐five of 96 initially normocalcemic (26%) cats followed for minimum 90 days developed ionized hypercalcemia (median, 1.46 mmol/L; range, 1.38‐1.80) at a median of 140 days after diagnosis of azotemic CKD (incidence rate, 0.48 per feline patient‐year). Only body condition score was independently associated with incident ionized hypercalcemia.Conclusions and Clinical ImportanceThe occurrence of ionized hypercalcemia is high in cats with CKD. Continued monitoring of blood ionized calcium concentrations is advised. 相似文献