不同记忆负荷对事件相关电位—P300的影响

我们研究了不同记忆负荷条件下,ERP-P_(300)变化的规律性和特点及ERP-P_(300)与脑力负荷难度之间的关系。在三种脑力作业时,要求受试者记忆2、4、6位随机数字。结果表明,1、随着记忆数字增加,P_(300)波幅相应增大,三种记忆作业P_(300)波幅之间均有显著性差异。2、记忆错误率和记忆难度主观评价值,亦随着记忆数字增加而增大,且在三种记忆作业之间均有显著性差异。3、P_(300)波幅和记忆难度主观评价值之间相关分析表明呈正相关(P<0.01)。我们建议,P_(300)波幅测量可以作为评价脑力负荷的一项客观指标。     

Altered enzyme activities of xenobiotic biotransformation in kidneys after subchronic administration of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) to rats

Activities of the xenobiotic metabolizing enzymes were measured in the liver, kidney, duodenum and lung microsomes and cytosol fractions of Wistar rats after subchronic administration of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), a potent bacterial mutagen in chlorinated drinking water. MX was administered by gavage at the dose level of 30 mg/kg for 18 weeks (low dose), or at the dose level which was raised gradually from 45 mg/kg for 7 weeks via 60 mg/kg for 2 weeks to a clearly toxic dose of 75 mg/kg for 5 weeks (high dose). Microsomal and cytosolic preparations were made and the activities of 7-ethoxyresorufin-O-deethylase (EROD), pentoxyresorufin-O-dealkylase (PROD), NADPH-cytochrome-c-reductase, UDP-glucuronosyltransferase (UDPGT) and glutathione-S-transferase (GST) were measured. Kidneys were affected most. A dose-dependent decrease was observed in EROD (90% in males, 80% in females at the high dose) and in PROD (58% in females, at the high dose) in kidneys. An increase was, however, detected in kidney NADPH-cytochrome-c-reductase (66% in females at high dose), UDPGT (89% in males and 97% in females at high dose) and GST activities (56% in males and 50% in females at high dose). MX caused only a few changes in the enzyme activities of the liver. The EROD activity was decreased 25% to 37%, both in the livers of males and females, but the total content of P450s was not altered. Hepatic GST activity was elevated in females in a dose-dependent manner (31% and 44%). GST activity was elevated in duodenum in females (59%) at the high dose. There were no marked changes in the enzyme activities in the lungs. MX was a weak inhibitor of EROD activity both in the liver and kidney microsomes in vitro, decreasing the EROD activity by 53% and 43%, respectively at the concentration of 0.9 mM. The results indicate that MX decreases the activity of phase I metabolism enzymes, but induces phase II conjugation enzyme activities, particularly in kidneys in vivo. It is possible that these changes contribute to metabolism of MX in kidneys and renders them susceptible to MX in the course of repeated exposure.     

江门市乡镇集中式供水卫生现状分析

为加强乡镇集中式供水卫生管理，进一步普及与提高农村的改水工作，我们按统一的调查方案，于１９９４￣１９９５年在全国范围内开展乡镇自来水厂调查登记和水质监测工作。据统计全市建成投产乡镇水厂６８座，普及率７７．３％，受益人口１４９．０９万，占农村总人口６２．５％，调查结果显示，水源总污染率为８．８２％，在监测项目中主查细菌学指标合格率不高，丰、枯水期水源水平均合格率分别为４０．０％和８８．９％，而出厂水     

老年患者不同证型红外热象舌图温度负荷的变化

目的 :探讨老年不同中医辨证分型的红外热象舌图温度负荷变化。方法 :被测试者分为阴虚证、阳虚证、气滞血瘀证、气血两虚证、湿热证五组。施以冷负荷后 ,红外舌图分析选取七个点温为代表 ,以计算机图像处理系统确定纵横坐标位置 ,对采录的所有红外舌图进行分析、处理。结果 :阴虚组舌尖、舌前两侧点冷负荷前后变化值与正常组比较 P<0 .0 5 ;阳虚组各点冷负荷前后变化值均低于正常组 (除 M点 ) ,且 T点、TL 点、TR点、M点均大于气血两虚组及湿热组 P<0 .0 5 ;气滞血瘀组舌温变化值低于正常 (T点 P<0 .0 5 ) ;气血两虚组各点温变化值均显著低于正常组 (P<0 .0 5～ 0 .0 1)及其他证型组 ;湿热组舌尖、舌前两侧点冷负荷前后变化值与正常组比较 P<0 .0 5 ,且低于阴虚组、阳虚组、气滞血瘀组。结论 :老年不同中医辨证分型的红外热象舌图各有其特征 ,红外热象舌图直观、重复性强 ,可作为中医辨证分型和疗效判断的临床指标     

Effect of compressive follower preload on the flexion-extension response of the human lumbar spine.

Traditional experimental methods are unable to study the kinematics of whole lumbar spine specimens under physiologic compressive preloads because the spine without active musculature buckles under just 120 N of vertical load. However, the lumbar spine can support a compressive load of physiologic magnitude (up to 1200 N) without collapsing if the load is applied along a follower load path. This study tested the hypothesis that the load-displacement response of the lumbar spine in flexion-extension is affected by the magnitude of the follower preload and the follower preload path. Twenty-one fresh human cadaveric lumbar spines were tested in flexion-extension under increasing compressive follower preload applied along two distinctly different optimized preload paths. The first (neutral) preload path was considered optimum if the specimen underwent the least angular change in its lordosis when the full range of preload (0-1200 N) was applied in its neutral posture. The second (flexed) preload path was optimized for an intermediate specimen posture between neutral and full flexion. A twofold increase in flexion stiffness occurred around the neutral posture as the preload was increased from 0 to 1200 N. The preload magnitude (400 N and larger) significantly affected the range of motion (ROM), with a 25% decrease at 1200 N preload applied along the neutral path. When the preload was applied along a path optimized for an intermediate forward-flexed posture, only a 15% decrease in ROM occurred at 1200 N. The results demonstrate that whole lumbar spine specimens can be subjected to compressive follower preloads of in vivo magnitudes while allowing physiologic mobility under flexion-extension moments. The optimized follower preload provides a method to simulate the resultant vector of the muscles that allow the spine to support physiologic compressive loads induced during flexion-extension activities.     

Lipoprotein lipase in relation to inflammatory activity in rheumatoid arthritis

Objective. To evaluate the impact of chronic inflammation on lipoprotein lipase (LPL) levels and triglyceride metabolism in patients with rheumatoid arthritis (RA). Design. Plasma levels of LPL activity and mass before and after heparin were determined in post-menopausal women with active RA and in controls. The results were related to lipid levels and inflammatory variables. The LPL activity and mass together with triglyceride levels were also measured before and 6 h after an oral fat load. Setting. The study was performed on in- and out-patients at a University Rheumatology clinic. The controls came from the same reference area. Subjects. Altogether 17 consecutive post-menopausal female patients with RA and 16 age and sex matched controls were enrolled for the initial determination of LPL. Fifteen of the patients and 15 of the controls agreed to take part in the fat load. Of these, one patient and one control were excluded. Main outcome measures. LPL determination: basal levels and post-heparin levels of LPL activity and mass. Correlations between LPL and blood lipids (cholesterol, triglycerides), lipoprotein levels (high density lipoprotein, HDL; low density lipoprotein, LDL), erythrocyte sedimentation rate (ESR) acute phase proteins (orosomucoid, haptoglobin, fibrinogen mass) and cytokines (tumour necrosis factor α, TNF-α; interleukin 1β, IL-1β; and interleukin-6, IL-6). Fat tolerance test: LPL activity, mass and triglyceride levels before and 6 h after a per oral fat load. Results. Pre-heparin LPL mass (P<0.01) and activity (P<0.01) were significantly lower in the rheumatoid patients. Pre-heparin LPL mass showed no correlation to the lipid levels, but an inverse correlation to several inflammatory parameters; it was significant for orosomucoid (r_s=?0.63, P<0.05) and C-reactive protein (CRP) (r_s=?0.54, P<0.05) and close to significant for haptoglobin (r_s=?0.48, P=0.087) and IL-6 (r_s=?0.52, P=0.061). Six hours after a lipid load the LPL activity and mass were significantly lower in RA (P<0.05 and P<0.01, respectively) but the triglyceride level was not significantly different compared to controls. Conclusion. An inverse relationship exists between inflammatory status and pre-heparin LPL mass. Pre-heparin LPL mass reflects mainly the inactive monomeric fraction of LPL. This has been shown to hinder the uptake of remnant lipoprotein particles through competition with lipoprotein bound dimeric LPL for the LDL receptor-related protein (LRP receptor) on hepatocytes and macrophages in culture. A decrease of the level of monomeric LPL in plasma may thus be beneficial for remnant catabolism. The same mechanism may on the other hand increase macrophage uptake of lipids. This may not affect global lipid metabolism but may be important in driving the atherosclerotic process in the vessel wall.     

关于在BOD_5测定中取样量的探讨

天子岭垃圾填埋场利用活性污泥法处理生活垃圾渗滤水,BOD_5测定的取样量公式为:V_i=k_1·V_(?)/COD_(cr),通过确定k_i值以确定取样体积.并分析了影响取样量的几种因素.     

8-羟基喹啉-5-磺酸-溴化十六烷基三甲铵荧光法测定水中铝的探讨

作者根据铝与8-羟基喹啉-5-磺酸(H_2QS)和溴化十六烷基三甲铵(CTMAB)的荧光反应,采用930型荧光计,测定水中铝含量在0～1.5μg/ml范围内有良好线性关系。方法的回收率为87.9％～105.0％,变异系数为2.9％～8.9％,铝的最低检出量和最低检出浓度分别为0.3μg和3×10~(-2)μg/ml。此法适于饮水和天然水中铝含量测定,具有灵敏、准确、所需仪器简单的特点。     

糖尿病性心血管病变与血清微量元素铁、铬、锰水平的相关性研究

本文研究糖尿病并发心血管病变时血清脂类、脂类过氧化产物与微量元素水平的相关性,结果发现:血清微量元素铁(Fe)与总胆固醇(T—ch)水平呈负相关,与水溶性荧光物质(WSFS)呈正相关;血清微量元素锰(Mn)与极低密度脂蛋白—胆固醇(VLDL—ch)呈负相关,与丙二醛(MDA)呈正相关;微量元素铬(Cr)与高密度脂蛋白—胆固醇(HDL—ch)呈正相关。提示:微量元素Fe、Cr、Mn为糖尿病性心血管病变的易患元素。     

Regulation of fluid intake in dogs following water deprivation

Whereas water loss in land living animals occurs continuously, water intake takes place discontinuously. At the normal operating set point of plasma osmolality, urine is more concentrated than plasma due to secretion of vasopressin. Thus animals operate around a state of mild dehydration. As water loss occurs, the severity of dehydration and thirst increase in intensity and at some point water intake occurs. Sufficient water is consumed to return plasma osmolality to the normal operating set point. Food intake and water balance are interdependent as food provides the osmoles which determine obligatory renal solute excretion. When dry food with the same osmotic content was substituted for canned food (water content 74%), dogs increased water intake from 24.2 +/- 4.3 to 62.2 +/- 8.8 ml/kg. Urine output and urine osmolality were unchanged, as under conditions of normal hydration, near maximal urine concentration is achieved. Changing water intake is the only available variable to maintain water balance. During water deprivation, the major renal mechanism appears to be natriuresis. In rehydration, satiety mechanisms ensure appropriate water intake and renal sodium conservation restores sodium balance.