Effects of bile acids on ventricular muscle contraction and electrophysiological properties: studies in rat papillary muscle and isolated ventricular myocytes

Summary The effects of sodium salts of various bile acids on the contractile force and the electrophysiological properties of rat ventricular muscle were studied in vitro. Primary, conjugated, and secondary bile acids were studied in a concentration range of 10^–9–10^–6 mol/l, which corresponds to concentrations found in the plasm of patients with cholestatic jaundice. In general, the bile acid induced a negative inotropic effect which was manifested as a reduction in active tension, maximum rate of tension activation, and maximum rate of tension relaxation. Twitch duration and time to peak tension were unaffected by the bile acids. The negative inotropism was associated with a reduction in ventricular action potential duration. Resting potential, action potential amplitude, and maximum upstroke velocity of phase 0 depolarization were unaffected. Voltage clamp experiments in rat ventricular myocytes demonstrated that sodium taurocholate decreased the slow inward current and slightly increased the outward potassium current. Hence, these effects on the membrane currents are probably responsible for the negative inotropic effect. Send offprint requests to O. Binah at the above address     

Relation of olfactory bulb and cortex. II. Model for driving of cortex by bulb

The major projection pathway of the olfactory bulb is by way of the lateral olfactory tract (LOT) to the olfactory cortex. Oscillatory bursts of extracellular potential appear during inspiration in both bulb and cortex. Based on anatomical and physiological considerations, a model was proposed, consisting of a bulbar transmitter, a conduction line representing axons in the LOT, and a cortical receiver. The model predicted the relation between phase and frequency of bulbar and cortical burst pairs, based on the expectation that the bulb drives the cortex. Experimental phase-frequency plots were computed from bursts of 9 bulbocortical electrode site pairs from each of 10 rabbits. For each site pair, the model predicted the expected range of the joint variation of phase and frequency, using the known distance between the bulbar and cortical sites. The model was highly successful (greater than 95% prediction accuracy) for one quarter of the total number of site pairs examined. The wide range of variation for the rest of the data suggested that higher order interactions are responsible for the phase relation between bulb and cortex. Convergence of input, independence of the cortical generator, cortical feedback to the bulb and synchronization by an outside source are all discussed as possible contributors to this variation.     

Discriminative conditioning-related slow potential and single-unit responses in the frontal cortex of urethane-anesthetized rats

A model is described for obtaining long-term and stable discriminative conditioning-related slow-potential and single-unit responses from the frontal cortex of urethane-anesthetized rats. Responses were recorded and analyzed to reinforced (rewarding medial forebrain bundle stimulation) and non-reinforced tone cues. In the present study, cortical event-related slow potentials provided an adequate index of the level of discriminative conditioning. Single-unit response patterns are described for 57 neurons which demonstrated a discriminative response to either the reinforced or non-reinforced tone cue.     

兔内听动脉阻断与听觉改变的关系

目的 探讨实验性内听动脉阻断与术后听力改变的关系及术中听觉监控的方法。方法 实验兔乙状窦后进路暴露小脑桥脑角，下压小脑暴露内听道及第Ⅷ神经复合体，分辨出内听动脉，予阻断不同时间，分别行蜗神经直接复合动作电位(DCAP)和畸变产物耳声发射记录(DPOAE)。结果对照组DCAPN1波潜伏期值无明显改变。内耳血供阻断10s和30s组在压迫开始后3min，DCAPN1波潜伏期值均恢复为初始值。内耳血供阻断1min组在压迫开始后3h，DCAPN1波潜伏期值未恢复为初始值假手术组DPOAE幅值无明显改变，内耳血供阻断10s、30s对DPOAE幅值无影响，内耳血供阻断1min使得DPOAE幅值下降结论兔内耳血供阻断1min可能造成兔听觉不可逆损伤。DCAP、DPOAE能有效、持续地监控内耳血供阻断，是耳神经外科手术中实用的听觉监测手段。     

小儿注射性坐骨神经损伤的脊髓运动诱发电位诊断

目的利用肌电图常规电刺激器测定脊髓运动诱发电位（MEP）技术，建立小儿注射性坐骨神经损伤诊断的新方法。方法采用英国Medelec公司生产的MS6型肌电图机，刺激器采用本机所配刺激器，刺激电压250～300mv，脉宽0．5～1ms。刺激电极为表面鞍型电极。刺激部位：负极处于L1棘突间，正极处于其上方。刺激方式为单次手动触发。记录部位为健、患侧胫前肌群及腓肠肌群。记录电极采用2支单极针电极。结果7例患儿主要异常形式表现为：诱发波的振幅降低，潜伏时延迟。结论测定表明该方法具有直接测定损伤段神经，异常表现出现早等优点。     

三氧化二砷诱导肝癌Bel-7402细胞凋亡与线粒体跨膜电位关系的研究

目的研究三氧化二砷（As2O3）诱导人肝癌细胞系Bel-7402细胞凋亡及与线粒体跨膜电位的关系。方法应用不同浓度的As2O3作用于肝癌细胞后，观察As2O3对肝癌细胞生长状态的影响；通过噻唑蓝（MTT）比色法观察其对Bel-7402细胞增殖的影响；利用共聚焦显微镜及流式细胞术观察经Annexin V-FITC／PI双染后的细胞早期凋亡；通过共聚焦显微镜及流式细胞仪检测线粒体跨膜电位（MMP）的改变情况；并通过底物染色法反映Caspase-3的活性。结果不同浓度的As2O3作用于肝癌细胞后有明显的时间和剂量依赖性；经Annexin V-FITC／PI双染后，可观察到Bel-7402细胞的早期凋亡现象，2μmol／L As2O3作用24h细胞凋亡率为9．89％，作用48h细胞凋亡率为48．53％，而4μmol／L As2O3作用24h细胞凋亡率为18．27％，作用48h细胞凋亡率为67．52％；经As2O3药物作用后，细胞线粒体膜电位水平下降，且与药物作用时间和药物浓度有关（P〈0．05）；同时Caspase-3活性被激活。结论As2O3可明显抑制肝癌细胞Bel-7402的生长，并使细胞线粒体膜电位下降，诱导肝癌细胞凋亡。     

Reassessment of the accuracy of traditional sperm characteristics and adenosine triphosphate (ATP) in estimating the fertilizing potential of human semen in vivo

Receiver operating characteristic curves and accuracy parameters were computed for traditional sperm characteristics (concentration, motility, morphology) and the number of peroxidase negative cells, and the concentration of adenosine triphosphate (ATP) in semen from populations of fertile and infertile men, and men who achieved a pregnancy after varicocele treatment. The percentage and concentration per millilitre of spermatozoa with rapid linear progressive motility, and the ATP concentration, provided the best discrimination between fertile and treated fertile from infertile men. The misclassification rate was higher for sperm morphology, total progressive motility and viability, whereas sperm concentration and the total sperm count per ejaculate had the worst discriminating power. The number of peroxidase negative cells per 100 spermatozoa was highly specific in identifying men who achieved pregnancy after varicocele treatment. The lower limit of normality of sperm characteristics was remarkably different between fertile men and men achieving pregnancy after treatment or during infertility work-up.     

脑瘫患儿脑干听觉诱发电位研究

本文采用日本光电公司生产的 MEB-5304K 诱发电位测定仪,对101名6月-14岁脑瘫患儿和40名正常儿测定了脑干听觉诱发电位(BAEP)。结果表明:给予80dBNHL,20Hz 刺激时 BAEP 异常率为45.54%,随刺激强度减小及刺激重复率增加,BAEP 阳性率提高。BAEP 改变与病情、病型及并发症有关。为脑瘫的发病机理及病理生理学研究提供神经电生理学依据。对脑瘫合并听力障碍者有助于及早选用助听装置,解决其听力障碍问题。     

用视诱发电位和富里叶变换作视力客观估计

目的:研究用图形视觉诱发电位(PVEP)和离散富里叶变换(DFT)作视力客观估计的方法。方法:检测对象为33只正常眼。用翻转频率为10次/秒,条纹张角分别为30、20、18、12、10、6、4和2弧分的垂直方波光栅图形刺激,记录相应的稳态图形视诱发电位。用离散富里叶交换提取WEP频谱中10Hz成分的幅值。以光栅条纹张角为横坐标、相应的VEP频谱幅值为纵坐标作关系曲线,取阈值附近的近似线性部分的数据点作直线回归,用外推法求得阈值和视力。结果:比较VEP所测之视力与用国际标准视力表所测之视力,可见在本研究中70％的受检眼VEP视力估计较准确。结论:用本研究中的VEP技术客观地测量视力可靠性较高。眼科学报1997;13:59～61。