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91.
笔者对吉林省8种优势种群吸血蠓的昼夜活动节律进行了观察.结果表明:华库蠓、孔库蠓、伊库蠓、原野库蠓、亚单带库蠓、淡角库蠓属于晨昏活动型蠓种;明边库蠓属于夜间活动型蠓种;浑江铗蠓属于白天活动型蠓种. 相似文献
92.
活性钙在大鼠体内吸收利用率的研究 总被引:6,自引:0,他引:6
目的对活性钙以度常用钙的朴钙效果进行比较研究.方法 选用3周断乳的wistar大鼠随机分为碳酸钙、醋酸钙、活性钙、磷酸氢钙、乳酸钙和基础6组,分别进行28d喂养及3d代谢实验。结果 活性钙组的增加体重大于磷酸氢钙、醋酸钙和基础组(P<0.05);活性钙的骨钙含量高于磷酸氢钙和基础组(P<0.05);活性钙组钙吸收率为71.7%;净利用丰为71.2%,结论 活性钙是一种良好的钙源,可以广泛用于食品添加剂和补钙药物. 相似文献
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David J. Stewart MD FRCPC G. Peter Raaphorst Jonathan Yau Arthur R. Beaubien 《Investigational new drugs》1996,14(2):115-130
Summary With chemotherapy, the in vitro and clinical dose-response curve is steep in some situations, but is relatively flat in others, possibly due to the mechanism by which tumors are resistant to chemotherapy. For tumors with resistance due to factors that actively decrease chemotherapy efficacy (e.g., p-glycoprotein, glutathione, etc.), one would predict that high dose chemotherapy and therapy with some resistance modulating agents would increase therapeutic efficacy. Such active resistance would most likely generally arise from gene amplification or over expression, and would be characterized by a shoulder on the log response vs. dose curve, with eventual saturation of the protective mechanism. On the other hand, one would expect that high dose chemotherapy and most resistance modulating agents would be of little value for rumors with resistance due to defective apoptosis or due to a deficiency in or decreased drug affinity for a drug target, drug activating enzyme, drug active uptake system, or essential cofactor. Such passive resistance would most likely generally arise from gene down regulation, deletion, or mutation, and would probably be characterized by a relatively flat log response vs. dose curve, or by a curve in which a steep initial section is followed by a plateau, as target, etc., is saturated. (If response were plotted vs. log dose, then compared to the curve for a sensitive cell line, the curve for active resistance would be analogous to the pharmacodynamic curve seen with competitive antagonism [i.e., a sigmoid curve shifted to the right], and the curve for most types of passive resistance would be analogous to the pharmacodynamic curve seen with noncompetitive antagonism [i.e., a sigmoid curve with reduced maximal efficacy]. As such, one might also refer to active vs. passive resistance as competitive vs. noncompetitive resistance, respectively.) Many tumor types probably possess a combination of active and passive mechanisms of resistance. New in vivo strategies could be helpful in defining dose-response relationships, mechanisms of resistance, and targets for resistance modulation. Such in vivo studies would be conducted initially in animals, but might also be tested clinically if animal studies demonstrated them to be feasible and useful. These in vivo studies would be conducted by randomizing 5–25 subjects to one of 10–20 dose levels over a potentially useful therapeutic range. Nonlinear regression analysis would then be used to define the characteristics of a curve generated by plotting against dose the log percent tumor remaining after the first course of therapy. While this might offer insight into the nature of resistance mechanisms present initially, plotting further tumor shrinkage vs. dose-intensity vs. course number for each later treatment course (or plotting dose-intensity vs. time to tumor progression) might provide information on how tumors become increasingly resistant to drugs following treatment. 相似文献
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Conventional teaching states that the retractile testis is a normal, physiological variant that descends spontaneously by puberty and requires no active treatment. Critical review of the literature, however, suggests that this complacent view may be inappropriate. Substantial overlap exists between the three seemingly separate entities of the late descending, the ascending and the retractile testes. This overlapping group probably accounts for the recently observed increased incidence of orchidopexies. Retractile testes that spend most of the time in an extrascrotal position are subject to the same adverse effects of higher temperatures as true undescended testes, regardless of whether they can be manipulated into the scrotum; what matters is where they actually reside most of the time. The evidence suggests that such retractile testes suffer similar pathological changes to true undescended testes if left to await spontaneous descent. Evidence is presented to support a radical, novel proposal that the retractile testis is a variant of the spectrum of pathological maldescended testes and requires active treatment. A new strategy is proposed for the management of this common pathology.
Correspondence to: D. W. Goh 相似文献
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99.
ZMS对老年大鼠脑内NGF和BDNF的影响 总被引:15,自引:3,他引:15
目的 研究自然衰老大鼠脑内两种神经营养素与学习记忆的关系 ,以及中药活性成分ZMS的作用。方法 用Y 迷宫测试动物的学习记忆功能 ,酶联免疫吸附分析法测定脑组织中BDNF和NGF的含量。结果 老年大鼠的学习和记忆成绩比青年大鼠差 (P <0 0 1) ,脑组织中BDNF的水平降低 ,NGF的变化无显著性。老年鼠喂服ZMS 2mon后 ,学习和记忆能力改善 ,正确次数 /反应总时间比值提高 (P <0 0 1) ,同时BDNF含量也高于老年组 (P <0 0 1)。但是ZMS对脑内NGF含量无影响。结论 ZMS能提高增龄引起的脑BDNF降低 ,从而对神经元起保护作用 ,这可能是ZMS改善老年大鼠学习记忆功能的重要机制之一 相似文献
100.
目的 观察豚鼠分泌性中耳炎时咽鼓管内表面活性物质的变化 ,探讨表面活性物质在分泌性中耳炎发病中的作用。方法 建立豚鼠分泌性中耳炎动物模型 ,分析咽鼓管内表面活性物质的生化成分和活性变化 ,同时观察给外源性表面活性物质治疗后咽鼓管内表面活性物质的变化。结果 豚鼠分泌性中耳炎模型组表面活性物质主要成分减少 ,磷脂酰胆碱 (phosphatidylcholine ,PC)和磷脂酰乙醇胺 (phosphatidylethanolamine ,PE)分别是 (19 9± 1 7) %和 (36 8± 2 7) % ,而正常组的PC和PE分别是 (2 5 7± 2 1) %和 (43 7± 3 8) % ,P值均 <0 0 0 1。模型组最低表面张力 (minimumsurfacetension ,γmin)为 (18 5± 2 4 )mN/m ,比正常组 (7 6± 0 8)mN/m升高 ,P <0 0 0l。给外源性表面活性物质治疗后 ,PC和PE增高 ,分别为 (2 3 3± 2 2 ) %和 (42 5± 3 6 ) % ,γmin降低 ,为 (11 8± 2 3)mN/m。结论 豚鼠分泌性中耳炎时咽鼓管内表面活性物质的主要生化成分明显减少 ,活性减弱 ,给外源性表面活性物质治疗后明显改善 相似文献