Cholesterol is an essential component of cellular membranes, but when present in excess in the circulation, can be deposited in the arterial wall, leading to the formation of atherosclerotic lesions. The principal plasma carrier of cholesterol, low density lipoprotein (LDL), is removed from the circulation by LDL receptors in the liver. This process plays a critical role in regulating plasma LDL levels. The unique structure and composition of the LDL particle makes it particularly susceptible to modification by oxidative reactions. Current evidence suggests that the production of oxidised LDL in the intima, and the removal of oxidised LDL particles by scavenger receptors on macrophages, play a central role in the development and progression of atherosclerotic lesions. 相似文献
Using the "canine model of the completely ischemic brain regulated with a perfusion method," the effects on cerebral ischemia of vitamin E, which is known to act as an antioxidant, were investigated. After pretreatment with vitamin E by oral or intravenous administration, cerebral blood flow was reduced to 1/10th the normal state and, 1 hour later, allowed to return to normal. Subsequent changes in electrical activity were observed, and the effects of vitamin E were evaluated. In the control group, no recovery of electrical activity was seen. In the groups given vitamin E, the recovery time was significantly shortened in the dogs given 30 mg/kg of vitamin E intravenously. Furthermore, in the groups treated with vitamin E, distinct recovery of electroencephalographic potentials at 3 hours after recirculation was apparent. These effects were more favorable in the case of intravenous administration than in the case of oral administration. These experimental results indicate that the administration of vitamin E is effective in protecting the brain from cerebral ischemia. 相似文献
Objective: To determine whether anionic ligands for the macrophage scavenger receptor inhibit the fertilization of mouse oocytes by mouse spermatozoa.
Design: In vitro study of sperm binding and two-cell embryo formation in the presence of scavenger receptor ligands. Sperm-oocyte interaction may be mediated by sulfated sugars. In this study, we tested other nonsulfated anionic ligands for the scavenger receptor for their ability to affect fertilization. The only common feature of these ligands is their anionic nature.
Setting: Oocytes and sperm from mice were used.
Main Outcome Measure(s): Binding of sperm to oocytes and subsequent formation of two cell embryos were determined.
Result(s): Fucoidin, polyinosinic acid, oxidized low-density lipoprotein, acetyl low-density lipoprotein, and malondialdehyde-modified LDL inhibited the binding and fertilization of mouse sperm to mouse oocytes. Addition of fresh sperm to oocytes previously treated with sperm in the presence of these agents restored the binding and fertilization.
Conclusion(s): These results show that charge-based interactions analogous to the interactions of the scavenger receptor with its ligands may play an important role in mammalian fertilization. 相似文献
No HeadingPurpose. Oxidative degradation of drug substances in pharmaceutical products is well documented and is thought to occur in many cases via autoxidative processes involving headspace molecular oxygen in the primary package. Reducing the headspace oxygen concentration inside a package could thus be an option for reducing oxidative degradation in pharmaceutical products. The purpose of this study is to examine the effect of headspace oxygen concentration and relative humidity (RH) on the oxidative degradation of a model pharmaceutical formulation.Methods. Model formulations, including a drug substance known to exhibit oxidative degradation, at two different drug/excipient ratios were packaged in stoppered glass vials maintained at different oxygen concentrations, (from 0% to 20.9%) and headspace relative humidities and were stored at 40°C. The oxidative degradation was quantified as a function of time.Results. The results clearly show dependence of oxidative degradation on headspace oxygen concen-tration, relative humidity, drug loading and time.Conclusions. The results provided insight into the effectiveness of inert atmospheric packaging (IAP) for protecting oxidation-labile products. In light of these observations, a few strategies for practically implementing inert atmosphere packaging are also presented. 相似文献