Gastric cancer etiology: a biochemical hypothesis.

We have proposed a two-stage biochemical model for the etiology of "intestinal" gastric cancer. The model postulates that the gastric mucosal barrier is biochemically pierced as a result of chemical interactions between the mucoproteins and mucopolysaccharides of the barrier and ingested polysaccharrides (starches). This would allow the growth of gastric flora which could produce carcinogenic nitrosamines and/or nitrosamides. Observational and experimental evidence in favor of the model is provided. The model suggests various research initiatives, the results of which might provide the basis for biochemical and physiological methods for the prevention and/or treatment of gastric cancer. Various ways in which the model may be tested are also noted.     

Electrical coupling, without dye coupling, between mammalian astrocytes and oligodendrocytes in cell culture

Evidence of electrical and dye coupling between oligodendrocytes and astrocytes was sought in cultures of mouse spinal cord. Cell identity was verified using cell specific antigenic markers. In most experiments current was injected into oligodendrocytes while recording voltage in nearby astrocytes. Nine of 17 oligodendrocyte-astrocyte cell pairs showed weak electrical coupling; the average estimated coupling ratio was 0.03 +/- 0.06 (cf. 0.11 for oligodendrocyte-oligodendrocyte and 0.44 for astrocyte-astrocyte pairs; Kettenmann and Ransom: Glia, 1: 64-73, 1988). Application of 0.5 mM BaCl2 or 44.6 mM CsCl depolarized astrocytes and oligodendrocytes and was estimated to increase the coupling ratio between these cells 3-5-fold; these effects were rapid in onset and completely reversible. In 5 of 7 cases, oligodendrocyte-astrocyte pairs that appeared uncoupled in normal solution exhibited coupling during Ba++ or Cs+ exposure. The actions of these cations are believed to be mediated by blockade of glial K+ channels. Depolarization, per se, as induced by increasing [K+]o, did not increase coupling ratio. The fluorescent dye lucifer yellow (LY) was injected into 10 oligodendrocytes, 8 of which were electrically coupled to nearby astrocytes, and never passed into astrocytes in detectable quantities. Likewise, astrocytes injected with LY stained other astrocytes, but never oligodendrocytes. These findings document the presence of weak electrical coupling between astrocytes and oligodendrocytes, in the absence of dye coupling. Weak coupling of this sort could subserve metabolic interactions between these cells mediated by the passage of small but important molecules such as cyclic AMP, but would not allow strong electrical interactions. If such coupling among glial cells is widespread, it would constitute a "metabolic syncytium" that could serve to coordinate glial behavior.     

恒温恒压电烫仪建立小鼠烫伤模型的实验研究

目的：寻求理想的建立小鼠不同深度烫伤模型的方法。方法：研制了恒温恒压电烫仪,分别以80度,0．5kg,2cm为统一的致伤温度,致伤压力,致伤直径,同时严格控制其他各个因素,以致伤时间为唯一可变因素,通过改变致伤时间,在小鼠背部建立不同深度的烫伤模型,并于烫伤后即时,4h,12,24h和48h取材病检。结果：建立浅II度,深II度及III度烫伤创面模型的致伤时间分别为5s,8s和12s;汤伤创面深度随病程逐渐加深,直至伤后24h才稳定,伤后48h的组织学改变类似伤后24h,结论：烫伤创面深度应以伤后24h创面深度稳定后的深度为诊断标准,本方法操作简单,所建模型稳定,重复性好,不失为一种建立小鼠不同深度烫伤模型的较为理想的方法。     

用钳夹法制作心肌缺血再灌注损伤模型的研究

目的:了解用无创伤动脉夹钳夹冠状动脉制作心肌缺血再灌注损伤模型的效果.方法:用无创伤动脉夹钳夹冠状动脉制作心肌缺血再灌注损伤模型37例.结果:此法的血流阻断的成功率及血管再通的成功率均是100%,血管损伤并发症发生率占5.4%(2/37).结论:钳夹法制作心肌缺血再灌注损伤模型的成功率及血管再通的成功率均为100%.而血管损伤并发症发生率低,钳夹法是一制作心肌缺血再灌注损伤模型的较好方法.     

难治性黄疸动物模型研究

目的：为难治性黄疸研究找到一种较为合适的动物模型。方法：１６只狗胆管壁浸润注射１％甲醛,１月内观察胆汁粘度和管壁病理形态学变化。结果：注射后胆管粘膜有进行性加重的炎症、粘膜脱落、纤维化及乃至管腔狭窄,其病理变化及临床的硬化性胆管炎病理特征基本符合。结论：本模型可望成为研究难治性黄疸的较为实用的动物模型。     

简易切割法制作健康SD成年大鼠hSCI和tSCI模型

用简易切割法制作ｈＳＣＩ和ｔＳＣＩ模型。４５只ＳＤ大鼠随机分为３组。ＩＳＣ组６只,ｈＳＣＩ组１８只,ｔＳＣＩ组２１只。用显微剪在Ｔ１３－Ｌ间横几完全剪断脊髓或其一则１／２,制成ｔＳＣＩ和ｈＳＣＩ模型,术后动态行为观察和神经功能综合评价,并分别于术后２４ｈ,７ｄ取Ｔ１１－Ｌ３节段脊髓作冻冻切片苏木精染色观察。结果显示,３组间ＣＢＳ两两比较经ｑ检验均有显著性差异。病理改变,ｈＳＣＩ组主要是伤侧伤质缩小     

大鼠拟血管性痴呆模型的建立及中药9602防治作用初探

用反复夹闭双侧颈总动脉(CCA)结合腹腔注射硝普钠将血压降低到50mmHg左右的方法复制了大鼠拟血管性痴呆的模型。结果表明脑缺血再灌注后7 d,行为学实验显示模型组大鼠出现明显的学习记忆障碍;形态学观察发现海马CA1区出现明显的细胞缺失,而CA3区无明显变化。中药9602可明显减轻脑缺血对海马的损伤,改善脑缺血引起的学习记忆障碍的作用。     

Richmond-Kotelchuck健康政策模式图的启示──我国预防医学模式转变中的三个关键问题

Richmond－Kotelchuck的健康政策模式图由科学知识基础、政治意愿和社会行为措施三部分组成。该模式图充分体现了三者对整个健康政策模式图的作用及其相互联系。随着社会的发展,我国当前正面临着转变预防医学模式的任务,借助于该模式图,本文论述了我国预防医学模式转变中值得注意的三个关键问题：科学研究、健康教育和举措设计。