Effects of octylguanidine on the electrical activity of Xenopus heart.

The effects of laboratory synthesized octylguanidine are described. There is an early decease of the maximum rate of rise of the action potential with negligible reduction of the overshoot although the membrane resting potential is unchanged. Subsequently, there is a remarkable reduction of both membrane potential and overshoot, while the plateau is shortened. The former effects resemble those seen with tetrodotoxin, the latter ones, with metabolic poisons.     

Time course of excitatory and inhibitory states of bulbar respiratory modulated neurons

Summary In respiratory modulated neurons of rabbits, vagally mediated inhibition is not bound to resting membrane potential oscillations. Latency of spinally evoked antidromical spike invasion, however, is shorter and threshold voltage is lower during the shift of membrane potential towards depolarization accompanying burst discharge.     

Contribution of divalent cations to the maintenance of membrane potentials in the oocytes of Pleurodeles waltlii Michah (Amphibia, Urodela)]

When the external concentration of Ca and Mg is changed, the oocyte membrane potential, in the Urodela Amphibian: Pleurodeles waltlii, is not significantly modified. The addition of chelator agents, EGTA and EDTA in Ca, Mg free Steinberg solution promotes a membrane depolarisation and the rise of membrane conductance. It is concluded that divalent ions Ca++ and Mg++ are needed to maintain a potential difference between internal and external medium of the oocyte.     

亚90nm沟道MOSFET亚阈值状态下二维电势和阈值电压的半解析模型

本文提出一个亚90nm沟道MOSFET在亚阈值状态下的二维电势和阈值电压的半解析模型．文章首先根据短沟道MOSFET在亚闽值状态下的物理模型提出定解问题,然后用特征函数将由氧化层和空间电荷区衔接条件所得到的超越方程组作正交展开,得到关于未知量的线性代数方程组．求出了氧化层和空间电荷区的二维电势、耗尽层厚度和阈值电压的表达式．该模型不需要适配参数,运算量小,避免了方程离散化,计算精度与数值解精度相同．文章给出了沟道长度为90nm以下MOSFET的电势分布、表面势、耗尽层厚度和阈值电压计算结果．计算值与二维数值模拟值高度吻合．     

Contributions of cellular electrophysiology to the understanding of the electrocardiogram

The understanding of cardiac action potential and membrane currents has broadened the theoretical foundation and enhanced the clinical usefulness of the electrocardiogram. An improved understanding of the morphology of the electrocardiographic waveform has resulted from: correlations between Vmax of depolarization and QRS complex, plateau of the ventricular action potential and S-T segment, terminal repolarization and T-wave, from definitions of action potential differences responsible for the T-wave, and recordings of action potential alternans. Cellular electrophysiology has contributed to the understanding of certain mechanisms of cardiac standstill. Many disturbances of conduction and refractoriness associated with ventricular arrhythmias can be attributed to the following derangements at the cellular level: slowing of terminal repolarization, development of diastolic depolarization in fibers with stable resting membrane potential, after-depolarizations, currents of injury resulting from non-uniform polarization, increased dispersion of action potential durations, and co-existence of slow conduction and short premature action potentials.     

Electrophysiological characteristics ofBombyx mori L. ventral nerve cord (effect of sodium and potassium on the membrane potential)

Summary Na⁺ and K⁺ effects on the resting cellular membrane potential of desheathed ganglia of theBombyx mori L. ventral nerve cord have been studied. The cells are depolarized by high concentrations of external potassium ions in the same way as in vertebrates, mollusca and crustacean cells. The possibility that the behaviour of the resting potential is not only influenced by the potassium equilibrium potential, but also by the conductances to other ions, is discussed.The authors are indebted to Prof V. Capraro, Drs B. Giordana and F. Sacchi for helpful comments and criticism.     

Anti-infective properties of bacteriocins: an update

Bacteriocin production is a widespread phenomenon among bacteria. Bacteriocins hold great promise for the treatment of diseases caused by pathogenic bacteria and could be used in the future as alternatives to existing antibiotics. The anti-infective potential of bacteriocins for inhibiting pathogens has been shown in various food matrices including cheese, meat, and vegetables. However, their inhibition of pathogens in vivo remains unclear and needs more investigation, due mainly to difficulties associated with demonstrating their health benefits. Many bacteriocins produced by established or potential probiotic organisms have been evaluated as potential therapeutic agents and interesting findings have been documented in vitro as well as in a few in vivo studies. Some recent in vivo studies point to the efficacy of bacteriocin-based treatments of human and animal infections. While further investigation remains necessary before the possibilities for bacteriocins in clinical practice can be described more fully, this review provides an overview of their potential applications to human and veterinary health.     

Effect of transmembrane potential on noradrenaline transport in chromaffin granules]

Imposing a transmembrane potential positive with respect to the medium on chromaffin granule ghosts increased the initial rate of the delta pH-induced uptake of noradrenaline, whereas imposing a negative potential decreased this rate. The increase of the uptake rate was proportional to the potential. The ATP-induced uptake of noradrenaline was also sensitive to the potential since imposing a transient negative potential onto the positive potential generated by the membrane ATPase induced a latency in this transport.     

城市土地集约利用潜力评价信息系统构建浅析

城市土地集约利用潜力评价是一项复杂的系统工程。在整合城市规划信息系统、多用途地籍信息系统、房地产开发与管理信息系统、城镇土地定级估价信息系统等的基础上开发城市土地集约利用潜力评价信息系统,可实现此项工作的一期自动化,日常管理更新动态化,从而推动土地工作向科学化、现代化方向发展。     

Contributions of cellular electrophysiology to the understanding of the electrocardiogram

Summary The understanding of cardiac action potential and membrane currents has broadened the theoretical foundation and enhanced the clinical usefulness of the electrocardiogram. An improved understanding of the morphology of the electrocardiographic waveform has resulted from: correlations between V_max of depolarization and QRS complex, plateau of the ventricular action potential and S-T segment, terminal repolarization and T-wave, from definitions of action potential differences responsible for the T-wave, and recordings of action potential alternans. Cellular electrophysiology has contributed to the understanding of certain mechanisms of cardiac standstill. Many disturbances of conduction and refractoriness associated with ventricular arrhythmias can be attributed to the following derangements at the cellular level: slowing of terminal repolarization, development of diastolic depolarization in fibers with stable resting membrane potential, afterdepolarizations, currents of injury resulting from non-uniform polarization, increased dispersion of action potential durations, and co-existence of slow conduction and short premature action potentials.     

Effects of intracellular or extracellular application of tetraethylammonium on the action potential in cultured chick embryonic heart muscle cell

Summary The effects of tetraethylammonium (TEA) on the action potential in cultured chick embryonic heart muscle cells were investigated. The onset of prolongation of the action potential occurred within 10 min following intracellular iontophoretic application of TEA, but after more than 50 min following extracellular application. These facts suggest that the major site of action of TEA is on the inner surface of the membrane in these cells.     

The action of cycloheximide on the action potential and protein synthesis in medullatedXenopus axons

Summary Cycloheximide depresses maximum rate of change in membrane potential observed during the rising phase of the action potential in single medullated axons ofXenopus. Time course of depression is independent of cycloheximide concentration over a range that almost completely inhibits leucine incorporation into axonal proteins.     

Linear constraints and the efficiency of combined forecasts

This note extends some recent results, achieved by Clemen, on constraining the weights of a combined forecast. There is a great potential for improving the ordinary least squares forecast by imposing linear restrictions, and it will be shown how this potential can be exhausted by using an F-test. The corresponding decision procedure leads to a pre-test forecast with good statistical properties.     

Effects of 1-alkyl-1,2,3,4-tetrahydrocarbazole-1-ethanamines and related compounds, potential antidepressants, on biogenic amine uptake mechanisms.

A new series of compounds structurally related to the potential antidepressant tandamine, i.e., the 1-alkyl-1,2,3,4-tetrahydrocarbazole-1-ethanamines, inhibit the noradrenaline uptake mechanism and are relatively ineffective in inhibiting the serotonin uptake mechanism in vivo. The potency of the most effective compound (9-ethyl-N,N,1-trimethyl-1,2,3,4-tetrahydrocarbazole) is similar to that of desimipramine and is of potential use in the treatment of endogenously depressed patients.     

Changes in transmitter release at frog neuromuscular junction induced by 4-aminopyridine]

4-aminopyridine (4-AP) at micromolar concentrations, increases the end-plate potential amplitude in curarized preparations and the mean quantal content in every preparation tested, but the spontaneous release is not modified by 4-AP. These results can explain the anticurare activity observed in the wole animal or in vitro. 4-AP prolongs the falling phase of the muscle action potential without change in the muscle membrane potential.     

美国休斯基金人才资助模式特征与启示

通过梳理美国霍华德·休斯医学研究所的几种主要人才资助模式，分析其特征，并提出在资助创新研究、培养创新人才、促进科技发展中值得借鉴的发展思路，得到四点启示与建议：要打破项目制的人才培养模式；在评价标准上突出人才的成长潜力；注重对有潜力人才的长周期培养；建立以科研为主的制度约束和保障。     

Zur wirkung hypertoner Lösungen auf die markhaltige Nervenfaser

Summary The effect of hypertonic solutions on the action potential of single myelinated nerve fibres is described. Hypertonicity mainly changes the duration of the action potential: Short action potentials obtained in normal Ringer's solution at room temperature are prolonged, long action potentials due to 0.1–1.0 mM NiCl₂-Ringer's solution and low temperature are shortened by hypertonicity. The changes in action potential duration are accompanied by small changes in action potential amplitude. In addition, hypertonicity reduces the depolarization produced by 20 mM KCl; inactivation of the sodium-carrying system under cathodal polarization is enhanced.

---

---

Die Untersuchungen wurden mit Unterstützung der Deutschen Forschungsgemeinschaft ausgeführt.     

Effects of 1-alkyl-1,2,3,4-tetrahydrocarbazole-1-ethanamines and related compounds,potential antidepressants,on biogenic amine uptake mechanisms

Summary A new series of compounds structurally related to the potential antidepressant tandamine, i.e., the 1-alkyl-1,2,3,4-tetrahydrocarbazole-1-ethanamines, inhibit the noradrenaline uptake mechanism and are relatively ineffective in inhibiting the serotonin uptake mechanism in vivo. The potency of the most effective compound (9-ethyl-N,N, 1-trimethyl-1,2,3,4-tetrahydrocarbazole is similar to that of desimipramine and is of potential use in the treatment of endogenously depressed patients.The authors acknowledge the technical assistance of Mrs J. Farnsworth, Mrs B. Gut and Mr J. Lacasse.     

Resting potential of excitable neuroblastoma cells in weak magnetic fields

The mechanism by which static and low-frequency magnetic fields are transduced into biological signals responsible for reported effects on brain electrical activity is not yet ascertained. To test the hypothesis that fields can cause a subthreshold change in the resting membrane potential of excitable cells, we measured changes in transmembrane current under voltage clamp produced in SH-SY5Y neuroblastoma cells, using the patch-clamp method in the whole-cell configuration. In separate experiments, cells were exposed to static fields of 1, 5, and 75 G, to time-varying fields of 1 and 5 G, and to combined static and time-varying fields tuned for resonance of Na+, K+, Ca2+, or H+. To increase sensitivity, measurements were made on cells connected by gap junctions. For each cell, the effect of the field was evaluated on the basis of 100 trials consisting of a 5-s exposure immediately followed by a 5-s control period. In each experiment, the field had no discernible effect on the transmembrane current in the vicinity of zero current (- 50 mV voltage clamp). The sensitivity of the measuring system was such that we would have detected a current corresponding to a change in membrane potential as small as 38 microV. Consequently, if sensitivity of mammalian cells to magnetic fields is mediated by subthreshold changes in membrane potential, as in sensory transduction of sound, light, and other stimuli, then the ion channels responsible for the putative changes are probably present only in specialized sensory neurons or neuroepithelial cells. A change in transmembrane potential in response to magnetic fields is not a general property of excitable cells in culture.     

The Na/K pump,resting potential and selective permeability in canine Purkinje fibres at physiologic and room temperatures

All mammalian cells maintain a resting potential generated by ions moving down concentration gradients. In excitable cells, the inside potential is negative relative to outside. In order to maintain this electrochemical gradient, the sodium potassium (Na/K) pump actively transports out three sodium ions for every two potassium ions it brings in. This process generates a net outward current and thus hyperpolaizes the resting potential. I employed dihydroouabain (DHO) to inhibit the Na/K pump and thus measure its contribution to the resting potential. It contributed 9.0 mV at 34°C and 3.8 mV at 25°C. The P_K/P_Na ratios were calculated at both temperatures before and after subtracting the Na/K pump contribution. These ratios also suggested a decreased contribution of the Na/K pump under hypothermia. Taken together, these results suggest that the pump contribution to the resting potential is more significant at physiologic temperatures (34°C) than at room temperature (25°C), and that estimates of selective permeability can only be accurately obtained after assessing and eliminating the Na/K pump contribution to the resting potential.