麦冬类中药组织切片计算机三维重建图鉴

利用计算机技术实现麦冬类中药组织连续切片三维重建与动态显示,为计算机辅助生药学鉴定和教学提供了新的三维图像技术和研究资料。     

表小檗碱对α受体的作用

表小檗碱(epiberberine,EB)是从湖北产黄连(Coptis chinensis Franch)中提取的一种生物碱,属苯喹嗪类原小檗碱,对其药理作用的研究资料甚少,未见其对α肾上腺素体作用的报道。资料表明,许多原小檗碱类化合物有α受体阻滞作用,为从该类化合物中选择     

Scientific and regulatory issues relevant to assessing risk for developmental neurotoxicity: an overview

The effects of chemical exposure on the developing nervous system have been documented in both humans and animals for a variety of agents. However, the comparability of these effects has not been carefully evaluated to determine the predictability of animal models to adverse effects in humans. A workshop sponsored by the U.S. Environmental Protection Agency (EPA) and the National Institute on Drug Abuse was held on April 11-13, 1989, to address the Qualitative and Quantitative Comparability of Human and Animal Developmental Neurotoxicity. Invited experts were asked to review the human and animal data on several agents that are known to cause developmental neurotoxicity in humans, including lead, methylmercury, selected abused agents, anticonvulsants, polychlorinated biphenyls (PCBs), ethanol and X-irradiation, and to make quantitative comparisons on a specific end point basis as well as on a functional category basis. In addition, they were asked to make quantitative comparisons when adequate dose-effect data were available. The data also were evaluated in the context of the proposed EPA developmental neurotoxicity testing battery to determine whether or not the battery would adequately detect the effects of each agent. Finally, four work groups were asked to reach consensus on issues relating to: 1) comparability of end points across species for developmental neurotoxicity; 2) testing methods in developmental neurotoxicity for use in human risk assessment; 3) weight-of-evidence and quantitative evaluation of data from developmental neurotoxicity studies; and 4) triggers for developmental neurotoxicity testing.     

T cell subsets mediating rejection of established fetal pancreas grafts and failure to observe graft adaptation

The present study has attempted to elucidate the cellular mechanisms by which long-term established fetal pancreas allografts are rejected. We used an experimental model in which H-2b nude mice were made hyperglycemic by streptozotocin treatment and then engrafted with allogeneic fetal pancreas grafts. These grafts were functional in that engrafted animals returned to near normoglycemia while all animals left unengrafted subsequently died. The fetal pancreas grafts were allowed to reside in the immunoincompetent nude host for 6-9 months prior to T cell reconstitution, at which time animals were reconstituted with either negatively selected CD4+ or CD8+ H-2b T cell subpopulations. We found that a 6-9 month residence in an immunoincompetent host did not lead to a change in the immunogenicity of fetal pancreatic grafts in that both CD4+ and CD8+ T cell subsets were capable of rejecting these long-term established fetal pancreas grafts. The finding that isolated CD8+ spleen T cell subpopulations, which are only activated by antigen-presenting cells of donor origin bearing MHC class I alloantigen, were capable of effecting graft rejection suggested that APC of donor origin persisted in these long-term fetal pancreas allografts.     

Biochemical parameters which may be useful in improving organ viability after storage.

Biochemical methods that accurately detect ischemic damage in livers stored by flush cooling would be useful in the efficient development of new storage solutions. This study compares UW and Collins' solutions to evaluate those biochemical parameters which may be useful in assessing the reversibility of ischemic damage and the efficiency of organ storage solutions. Livers stored in UW solution showed higher levels of adenine nucleotides at all storage times studied. This increase in adenine nucleotides averaged 29% and was statistically significant. There was also a significant increase in the NAD levels in organs stored in UW solutions; however, the ATP levels were not significantly different after storage in either solution. Storage of livers in UW solution also decreased the amount of DNA damage which occurs with storage as compared to storage in Collins' solution, becoming statistically significant after 48 hr of storage. This suggests that these biochemical parameters may be useful in designing improved storage solutions since they reflect the extent of ischemic damage to the organ and can be determined on a small section of liver taken by biopsy.     

Evaluation of myocardial metabolism with microdialysis during bypass surgery with cold blood- or Calafiore cardioplegia.

BACKGROUND: For the first time, microdialysis was used to investigate in vivo and online the myocardial metabolism during and after cardiac surgery in patients treated with two different methods of myocardial protection. METHODS: Thirty patients underwent standard CABG with one of two different methods of myocardial protection. The patients were randomised to receive either cold blood (COLD group) or warm modified Calafiore cardioplegia (WARM group). Microdialysis probes were implanted into the myocardium of left ventricular apical region of the heart. Cardioplegia was given antegrade only. Microdialysis measurements were performed at time intervals before, during and 24 h after cardiopulmonary bypass and analysed for glucose, lactate, pyruvate and glycerol. RESULTS: Myocardial lactate concentrations were significantly higher in the WARM group compared with that of the COLD group, while serum lactate was comparable. Glycerol was significantly higher at the end of the clamping time in the WARM group. At the same time the glucose-lactate ratio as a marker of nutritional disorder had significantly lower levels in the WARM group. The cumulative CK-MB release over 24 h was significantly higher in those hearts protected with warm blood. CONCLUSIONS: The oxidative stress measured was significantly higher in patients undergoing CABG using modified Calafiore cardioplegia, whereas the cold cardioplegia minimised the effects of aortic clamping. The results indicate that cold cardioplegia offers superior protection of the heart, in terms of more rapid normalisation of myocardial metabolism. In elective myocardial revascularisation, intermittent antegrade warm blood cardioplegia is a comparable safe method of myocardial protection. However, in patients referring to a long clamping time, advantages of cold cardioplegia for myocardial revascularisation may be magnified.