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排序方式: 共有478条查询结果,搜索用时 15 毫秒
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Synthesis,Characterization, and in Vitro Stability of Chitosan-Methotrexate Conjugates 总被引:1,自引:0,他引:1
Pharmaceutical Research - 相似文献
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Oxygen lack as a possible cause of reactive hyperemia 总被引:1,自引:0,他引:1
Crawford Dewitt G.; Fairchild Hilton M.; Guyton Arthur C. 《The American journal of physiology》1959,197(3):613-616
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The effects of in vivo physiologic doses of vasopressin and 1-deamino-8-D-arginine vasopressin (DDAVP) on the cyclic AMP content of plasma, urine, and renal papillary tissue were determined in the ADH-deficient Brattleboro rat. During clearance studies, plasma cyclic AMP concentrations and both total and nephrogenous urinary cyclic AMP excretion in vasopressin- and DDAVP-treated rats were similar to the values in time-matched controls. In contrast, in situ renal papillary cyclic AMP content was higher (P less than 0.001) in both vasopressin- (35.7 +/- 3.6 pmol/mg protein) and DDAVP- (29.7 +/- 2.2 pmol/mg protein) treated rats compared to controls (15.1 +/- 1.3 pmol/mg protein). Endogenous stimulation of vasopressin by dehydration in normal rats increased both papillary cyclic AMP content (27.1 +/- 2.7 pmol/mg protein) and urine osmolality, whereas no change in papillary cyclic AMP was observed following dehydration in Brattleboro rats (13.6 +/- 0.8 pmol/mg protein) despite an increase in urine osmolality. The results demonstrate that changes in cyclic AMP following in vivo vasopressin are best demonstrated by measurement of in situ cyclic AMP content of the renal papilla, whereas total urinary cyclic AMP and nephrogenous cyclic AMP are not useful indices of tubular sensitivity to this hormone. 相似文献
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Jolinda LD Schram Joost Oude Groeniger Merel Schuring Karin I Proper Sandra H van Oostrom Suzan JW Robroek Alex Burdorf 《Scandinavian journal of work, environment & health》2021,47(2):127
Objective:Using a novel mediation method that presents unbiased results even in the presence of exposure–mediator interactions, this study estimated the extent to which working conditions and health behaviors contribute to educational inequalities in self-rated health in the workforce.Methods:Respondents of the longitudinal Survey of Health, Ageing, and Retirement in Europe (SHARE) in 16 countries were selected, aged 50–64 years, in paid employment at baseline and with information on education and self-rated health (N=15 028). Education, health behaviors [including body mass index (BMI)] and working conditions were measured at baseline and self-rated health at baseline and two-year follow-up. Causal mediation analysis with inverse odds weighting was used to estimate the total effect of education on self-rated health, decomposed into a natural direct effect (NDE) and natural indirect effect (NIE).Results:Lower educated workers were more likely to perceive their health as poor than higher educated workers [relative risk (RR) 1.48, 95% confidence interval (CI) 1.37–1.60]. They were also more likely to have unfavorable working conditions and unhealthy behaviors, except for alcohol consumption. When all working conditions were included, the remaining NDE was RR 1.30 (95% CI 1.15–1.44). When BMI and health behaviors were included, the remaining NDE was RR 1.40 (95% CI 1.27–1.54). Working conditions explained 38% and health behaviors and BMI explained 16% of educational inequalities in health. Including all mediators explained 64% of educational inequalities in self-rated health.Conclusions:Working conditions and health behaviors explain over half of the educational inequalities in self-rated health. To reduce health inequalities, improving working conditions seems to be more important than introducing health promotion programs in the workforce. 相似文献
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Characterization of xenobiotic-metabolizing enzymes and nitrosamine metabolism in the human esophagus 总被引:5,自引:2,他引:5
Smith TJ; Liao A; Wang LD; Yang GY; Starcic S; Philbert MA; Yang CS 《Carcinogenesis》1998,19(4):667-672
Esophageal cancer has been associated with tobacco smoking, and
nitrosamines are possible causative agents for this cancer. The present
study investigated the metabolism of the tobacco carcinogens N'-
nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1- butanone
(NNK), and N-nitrosodimethylamine (NDMA), as well as the presence of
xenobiotic-metabolizing enzymes in human esophageal tissues from
individuals in the United States and Huixian, Henan Province, China (a
high-risk area for esophageal cancer). All esophageal microsomal samples
activated NNN and the metabolic rate was 2-fold higher in the esophageal
samples from China than the USA. All microsomal samples activated NDMA.
However, most of the microsomal samples did not activate NNK.
Troleandomycin (an inhibitor of cytochrome P450 3A) decreased the formation
of NNN-derived keto acid by 20-26% in the esophageal microsomes. The
activities for NADPH: cytochrome c reductase, ethoxycoumarin O-deethylase,
NAD(P)H: quinone oxidoreductase and glutathione S-transferase were present
in the esophageal samples. Coumarin 7-hydroxylase (a representative
activity for P450 2A6) activity was not detected in the esophageal
microsomal samples. The activities for nitrosamine metabolism and
xenobiotic- metabolizing enzymes were decreased (by 30-50%) in the squamous
cell carcinomas compared with their corresponding non-cancerous mucosa. The
presence of activation and detoxification enzymes in the esophagus may play
an important role in determining the susceptibility of the esophagus to the
carcinogenic effect of nitrosamines. Our results suggest that P450s 3A4 and
2E1 are involved in the activation of NNN and NDMA, respectively, in the
human esophagus.
相似文献