颈动脉内注入腺苷对呼吸,血压和肾交感神经活动的影响

在33只麻醉家兔,观察了颈动脉内注入腺苷所诱发的平均动脉压、心率,呼吸和肾交感神经活动的变化。结果如下:(1)颈动脉内注入腺苷后,平均动脉压呈剂量依赖性下降;呼吸加快,深度变化不明显,剪断窦神经后注入腺苷,仍引起平均动脉压下降,而呼吸变化消失。(2)隔离的颈动脉窦灌流液内加入腺苷后,平均动脉压下降,心率减慢;颈动脉体(CB)失活后反应消失。(3)将腺苷灌注到颈动脉窦区后,平均动脉压下降,肾交感神经传出放电活动增加,CB 失活或剪断窦神经后,反应消失。由此提示:腺苷可作为兴奋 CB 的一种物质,引起平均动脉压降低,心率减慢,呼吸加强和肾交感神经放电活动增加。     

Superoxide dismutase in vegetative cells, heterocysts and akinetes of Anabaena cylindrica Lemm

Abstract: Superoxide dismutase (SOD) activity was assayed in vegetative cells, heterocysts and akinetes of Anabaena cylindrica Lemm. The iron-containing isoenzyme (Fe-SOD) was in all cases predominant over the manganese-containing isoenzyme (Mn-SOD). Differentiated cells maintained the same relative content of the two enzymes as in vegetative cells. However, heterocysts and akinetes contained only 20 and 35%, respectively, of the total SOD activity present in vegetative cells.
Both Mn-SOD and Fe-SOD activities increased in all types of cells isolated from A. cylindrica grown at high light intensity. The increase of SOD in heterocysts paralleled that of nitrogenase, suggesting a role of SOD in the protection mechanism of nitrogenase.     

Enhancement of ATPase Activity by a Lipid Peroxide of Arachidonic Acid in Rat Brain Microvessels

The effects of 15-hydroperoxyarachidonic acid (15-HPAA) on Na+, K+- and Mg+-ATPase activities in the blood-brain barrier (BBB) were examined using rat brain microvessels (MV). 15-HPAA markedly stimulated these ATPase activities in MV at low concentrations whereas the synaptosomal Na+, K+-ATPase activity was inhibited in a dose-dependent manner. Further neurochemical analysis revealed that this stimulatory effect of 15-HPAA in MV was not due to a simple detergent-like action of the compound on the membranes but rather to stimulation of the phospholipase A2 and lipoxygenase activity within MV. In addition, it was shown that free radical reactions were involved in the mechanism. Since such anti-edema drugs as 1,2-bis(nicotinamido)propane were proved to be potent suppressors of the enhanced ATPase activity, further speculations on the role of this effect for ischemic brain edema are offered.     

Monoamine Neurotransmitter Metabolism and Locomotor Activity During Chemical Hypoxia

The effects of hypoxia on metabolism of 5-hydroxytryptamine (5-HT or serotonin) and 3,4-dihydroxyphenylethylamine (DA or dopamine) were compared with those on open-field activity in male CD-1 mice. Chemical hypoxia was induced with NaNO2. Hypoxia did not alter striatal concentrations of DA, 5HT, Trp, Tyr, 5-hydroxyindoleacetic acid, or homovanillic acid. However, NaNO2 (75 mg/kg) reduced the rates of conversion of [3H]Tyr to [3H]DA (-41%) and [3H]Trp to [3H]5-HT (-39%). Hypoxia also reduced dihydroxyphenylacetic acid (DOPAC) levels (-27%) and DOPAC/DA ratios (-20%). Open-field behavior, as measured in an automated activity monitor, decreased in a dose-dependent fashion with 75-150 mg/kg of NaNO2 (-35 to -90%). Comparison with previous studies suggests that the syntheses of dopamine, serotonin, and the amino acids are equally vulnerable to hypoxic insults but may be less sensitive than the synthesis of acetylcholine.     

Effect of base substitutions in the colicin E1 gene on colicin E1 export and bacteriocin activity

Summary Base substitutions have been introduced into the segment of the colicin E1 gene corresponding to the polypeptide region between the 404th and the 502nd residues which was considered to participate in colicin E1 export and bacteriocin activity. The methods used were in vitro localized mutagenesis with sodium bisulphite and in vivo mutagenesis using either nitrosoguanidine or ethyl methane sulphonate. Cells carrying mutagenized plasmids were screened by their inability to form a clear zone on a lawn of colicin E1 sensitive cells. Mutation sites were determined from the nucleotide sequence analysis and the altered amino acid residues were reduced. The mutant proteins were analysed for their ability to be exported to the periplasmic space and for their bacteriocin activity. Out of eight mutants obtained, three had a single amino acid replacement. Mutant proteins that had Ser and Glu in place of Pro-462 and Gly-502, respectively, showed a decrease in both the export and the bacteriocin activity. A mutant protein having Arg in place of Gly-439 showed a decrease only in the bacteriocin activity. These results suggest that the target region of colicin E1 contributes to the export as well as the bacteriocin activity but the two functions are supported in part by different amino acid residues of the protein.     

人体急性缺氧性意识障碍

实验分为低压组(低压舱7,000米)与常压组(吸入7.6％低氧混合气),每组受试者各为12名,有7名参加了两组实验。每组各有4名平均经15分23秒发生了意识模糊或丧失(通称意识障碍)。障碍者的肺泡氧分压为29.9±0.8mmHg。障碍发生前,呈现严重无力,觉醒度降低,反应迟钝,脑波特征是高幅6波(100-300μV)占优势。障碍发生时,高幅δ波丧失节律,幅度衰减,波型不规则,额枕失同步;呼吸循环代偿功能增强程度明显高于障碍前。本工作对于预测和评价人体急性缺氧引起的意识障碍有意义。     

电离辐射引起胃排空延迟机理的初步探讨

本文观察了800rad照射后胃肠肌电的变化及切斷内脏神经与电刺激迷走神经对官的影响,初步分析了电离辐射引起胃排空延迟的机理。结果是:800rad照后大鼠胃肠肌电的峰波平均振幅胃幽部窦部照后1小时至第4天明显降低(P<0.05);幽门括约肌政变不大;十二指肠球部照后第3～7天明显下降(P<0.01)。切断内脏神经后照射大鼠胃肠肌电的峰波平均振幅胃幽门窦部变化不大,幽门括约肌照后1小时至第5天明显升高(P<0.05),十二指肠球部照后第3～7天明显下降(P<0.05)。800rad照后第4天大鼠胃对电刺激迷走神经的反应性明显降低(P<0.01)。上述结果表明:照后胃排空延迟的原因不仅与神经-体液调节紊乱有关,而且与射线损伤了平滑肌,使其兴奋性暂时的功能性降低有关。此外照后由于十二指肠球部运动的变化而使内感受器对胃运动的调节发生紊乱也是值得重视的因素。     

体外分化的人体巨噬细胞抑制天然杀伤(NK)细胞的研究

本文继先前工作后,进一步应用正常健康人外周血单个核细胞(PBMNC)经塑料培皿粘附技术把单核细胞分离出来,经培养进一步纯化,随后动态观察培养0,2,4,6和8天的单核-巨噬细胞的形态变化和对新鲜分离同种异基因个体PBMNC中NK活性的影响。实验表明,体外分化6天和8天的巨噬细胞质/核比例和胞浆内空泡显著增加,细胞直径约为0天时的2倍。这些细胞和PBMNC之比为0.5:1时,引起了NK细胞活性的50%以上抑制(4小时~(51)Cr标记K 562肿瘤的同位素释放试验)。这种抑制效应不为过氧化氢酶(Catalase 4000单位/毫升)和前列腺素合成酶的抑制剂(Indom 1×10~(-5)M)所阻断。实验证明,同种异基因个体的NK细胞不能识别巨噬细胞表面抗原,从而排除了巨噬细胞和K562肿瘤抗原竞争的可能性。实验还表明,巨噬细胞对NK活性的抑制是不受HLA约束的。应用高频超声振荡破碎巨噬细胞膜方法和免疫调变技术进一步提示,人体巨噬细胞对NK活性的抑制与巨噬细胞体积无关,而与体外分化所赋有的固有特性和它们分泌的免疫调节分子有关。     

The influence of level of infection of rats with Nippostrongylus brasiliensis on the haematology and phospholipase activity and mast cell numbers in the small intestine and colon

The haematology and phospholipase activity and mast cell numbers of the small intestine and colon of rats was studied 10 days after infection with various numbers of larvae of N. brasiliensis. A significant reduction in the RBC occurred after infections with 200 and 5000 larvae but not with 1000 larvae. Hb was significantly reduced after infection with 200 larvae and increases in the MCV and MCH indicated the development of a macrocytic anaemia. Reticulocyte count was increased at all levels of infection except after 200 larvae. WBC was increased at all levels of infection except in the 5000 larvae group. Lymphocytes were significantly increased in all groups except those infected with 5000 larvae. Neutrophils increased only at the lower levels of infection. The most marked changes occurred in eosinophil numbers, significant increases occurring with increasing levels of infection. However, after infection with 5000 larvae the numbers were significantly lower than after infection with 200 or 1000 larvae. Phospholipase activity, which is believed to be related to tissue eosinophil levels, was significantly increased at all infection levels in the proximal small intestine. Significant increases in the distal ileum and colon occurred mainly after infection with 1000 and 5000 larvae. Mast cell numbers did not change significantly at any infection level. It is suggested that the pathology observed, here in the form of anaemia, is multifactorial in origin and is largely a function of the immune response, the development and expression of which is dependent on the level of infection, with suppression of immune damage occurring at the high levels of infection when pathogenesis may involve a direct effect of the worms.     

Nippostrongylus brasiliensis: feeding activity in the mouse

Nippostrongylus brasiliensis incorporated the fluorescent dye, Rhodamine B, while feeding in vivo. Uptake of dye in both sexes of helminth increased linearly from 30 to 120 min after the hosts were given dye per os. Feeding by female N. brasiliensis significantly exceeded that of the male at 4 and 5 days postinfection. Feeding declined in older helminths of both sexes. The density of helminths had no effect on their incorporation of dye in vivo. Feeding in male- and female-only groups of worms was similar to that seen in populations of mixed sexes. Feeding by helminths decreased during the first 36 h of food deprivation in the host, but increased during subsequent fasting of the host. Both sexes of N. brasiliensis resumed feeding within 15 min after the fasted hosts were fed. Growth of N. brasiliensis increased linearly from 4 to 7 days postinfection, based on dry weight. Seven-day-old and older females were significantly heavier than males.