Super-reactivity to amphetamine toxicity induced by schedule of reinforcement

The chronic exposure of rats to a schedule of operant water reinforcement coupled with chronically restricted access to water sensitized the animals to intermittentd-amphetamine injections (0.31–2.5 mg/kg with intervals of 12–23 days between any two injections) in such a way that this drug came to produce catastrophic losses of body weight (32.4% of control levels). In the sessions whend-amphetamine was administered, the rats were also given a total of 12 brief electric shocks. Loss of body weight was unaccompanied by parallel changes in operant behavior performance, or in food or water intake. Remarkably, in other studies with the same interventions (sham schedule sessions, water deprivation, and foot shocks), with the exception that reinforcers were never delivered,d-amphetamine did not produce catastrophic falls in body weight. This super-reactivity tod-amphetamine toxicity may be mediated by a possible stressor action of the schedule of reinforcement. Its mechanism might be analogous to the known sensitization produced by classical experimental stressor stimuli to the repeated administration ofd-amphetamine.     

Distinguishment of A 42 Capsomere Structure of Icosohedral Virion from A 32 One by Electron Microsco

ＤｉｓｔｉｎｇｕｉｓｈｍｅｎｔｏｆＡ４２ＣａｐｓｏｍｅｒｅＳｔｒｕｃｔｕｒｅｏｆＩｃｏｓｏｈｅｄｒａｌＶｉｒｉｏｎｆｒｏｍＡ３２ＯｎｅｂｙＥｌｅｃｔｒｏｎＭｉｃｒｏｓｃｏｐｅＣｎｅｎＢｉｎｇｙｉｎｇ（陈丙莺）；ＺｈｏｕＴｏｎｇ（周）（Ｄｅｐａｒｔｍｅ...     

三种调味品对小鼠内脏器官的影响

目的探讨过量八角、花椒及桂皮对小鼠内脏器官的影响。方法分别使用不同浓度三种调味品的提取液灌胃 ,采用病理学检验技术 ,观察小鼠肝脏、肾脏等器官的病理学变化 ,并计算出肝、肾、脾的脏体系数。结果调味品各组小鼠的肝脏、肾脏和脾脏重量都有所增加 ,脏体系数有不同程度升高 ,与正常组比较 ,差异具显著性 (P <0 .0 5 ,P <0 .0 1 )。肝脏、肾脏可见明显形态学改变 ,肝脏的损伤主要表现在肝细胞胞浆疏松化和气球样变 ,甚至出现双核、巨核和分裂相。肾脏损伤主要表现为肾小管上皮细胞水肿 ,肾小球毛细血管充血、出血。脾脏未见明显改变。结论三种调味品过量使用时 ,对小鼠肝脏、肾脏和脾脏有不同程度的损伤 ,但病变的程度与调味品的剂量关系不大 ,而与其种类关系较密切。八角的毒性反应最为明显 ,桂皮次之 ,花椒的影响较小     

氧化损伤与铅毒性研究进展

铅是一种对全身组织有广泛亲和力的毒物,作用的基点是体内一些生物大分子(蛋白质、脂类、核酸),进而使大分子受损,影响到细胞功能.     

酥胆麒麟膏用于痔瘘术后换药的药效学与毒理学研究（二）

本文通过设一个阳性对照组（马应龙鹰香痔疮膏），一个空白对照组（凡士林）及酥胆麒麟膏大、中、小三个剂量组（１０％、２０％、４０％浓度）进行三个方面的实验研究，证实酥胆麒麟膏具有止血、抗菌、生肌长皮等综合作用，局部外用无毒副作用，安全性高。其止血、生肌长皮作用，优于马应龙麝香痔疮膏；抗金葡萄茵的作用与银灰散相同；抗大肠杆菌的作用犹于银灰散。尤其是２０％酥胆麒麟膏的以上多种作用优于１０％浓度的，等效于４０％浓度的，可作为临床使用时的最佳浓度。     

镉对大鼠肾脏和睾丸毒性的比较

大鼠饮水中给镉12wk后,检测了尿低分子蛋白(LMWP)排出量。尿碱性磷酸酶(ALP)活性,血清睾酮水平,睾丸乳酸脱氢酶同功酶(LDH-X)活性,精子计数和形态,雄鼠生育力,肾,睾丸和附睾组织镉含量,并在光镜和电镜下观察上述组织的病理变化,从生化,形态和功能改变三方面比较了大鼠肾脏和睾丸对镉的敏感性,发现尿LMWP和ALP仅在高剂量组显著增加,而血清睾酮和睾丸LDH-X在中剂量纽和低剂量纽已明显降低,说明镉对睾丸的有害作用可出现在肾脏之前。     

邻甲苯胺的毒性研究

邻甲苯胺经口半数致死量为７５５ｍｇ／ｋｇ，属低毒类。动物染毒邻甲苯胺１９ｍｇ／ｋｇ以上引起小鼠脾脏增大，３８ｍｇ／ｋｇ以上引起白细胞计数升高，且淋巴细胞百分比升高，各染每剂量对小因清免疫球蛋白ＩｇＧ含量和巨噬细胞吞噬功能无明显影响。结果表明，邻甲苯胺对造血系统有影响，对免疫系统无明显直接影响。     

Kohl: a hazardous eyeliner

Kohl is a widely used traditional cosmetic. It is mainly worn around the eyes in the Middle East, Asia and Africa. The elemental composition of twenty-one kohl specimens originating from various parts of Saudi Arabia, India and the Middle East was determined by energy dispersive X-ray analysis (EDAX). The data indicates the presence of significant lead levels in two thirds (14/21) of the kohl specimens ranging from 2.9–100 (mean 48.5). Other less frequent elements present in kohl preparations include aluminum, carbon, iron, titanium, calcium, magnesium, oxygen, silver silicon, sulfur and antimony. Seven kohl specimens were totally lead-free, four had a lead content in the range of 2.9–34.1 and ten had lead levels in excess of 84. Carbon levels in excess of 60 were detected in six kohl samples. Antimony was present in only one kohl specimen at a concentration of 7.8.Five western made eyeliner pencils analyzed for comparative purposes consistently revealed iron as a common constituent (mean 46) but no lead or carbon were detected in these specimens.The findings of this study indicate that modern kohl preparations contain a number of metals derived from natural sources in addition to carbon. The predominance of lead in the kohl preparations tested is of major concern due to the documented adverse effects in humans and the increased susceptibility of children to lead intoxication. Application of lead-containing kohl needs to be considered as a source of lead in evaluating patients with symptoms of lead intoxication in regions where this tradition prevails. The documented toxic effects of lead in humans and the increased sensitivity of children to lead exposure serve to emphasize potential health risks of using traditional lead containing kohl preparations and the need for increased surveillance and regulation of the manufacture of kohl.The opinions or assertions contained herein are the private views of the author and are not to be construed as official or as reflecting the views of the Department of the Army or Department of Defense.     

Species- and sex-specific variations in binding of ochratoxin A by renal proteins in vitro

The mycotoxin ochratoxin A (OTA) is a potent renal carcinogen in rodents and induces renal fibrosis in pigs. Furthermore, OTA has been associated with the development of renal tumors and nephropathies in humans. Large species- and sex-differences are observed in sensitivity toward OTA-mediated toxicity and carcinogenicity, yet neither the mechanism(s) resulting in OTA toxicity nor the reasons for the observed species- and sex-specificities are known. This paper investigated variations in OTA handling viz binding to renal proteins which could possibly explain the observed differences in OTA susceptibility in vivo and in vitro. The results obtained via a modification of a standard receptor-binding assay demonstrated the presence of at least one homogeneous binding component in renal cortical homogenates from pig, mouse, rat and humans. This component was shown to bind OTA in a specific and saturable manner. A range of compounds selected for their affinity for steroid receptors and/or for various known organic anion transporters were employed in a competition assay to answer the question whether this homogenous OTA binding component represents a steroid-like receptor component or one of the known organic anion transporters of the kidney. Although many of the compounds were able to compete with OTA for protein-binding, the competition patterns displayed a distinct species specificity and did not correspond to the competition patterns associated with presently known organic anion transporters of the kidney in the mouse, rat or human. The data thus suggests the presence of a new organic anion transporter or more likely, a cytosolic binding component of unknown function with high affinity and capacity for OTA binding in humans, rats, mice and possibly pigs.