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The contribution of T-, L-, N-, P-, and Q-type Ca2+ channels to pre- and postsynaptic Ca2+ entry during stimulus-induced high neuronal activity in area CA1 of rat hippocampal slices was investigated by measuring the effect of specific blockers on stimulus-induced decreases in extracellular Ca2+ concentration ([Ca2+]o). [Ca2+]o was measured with ion-selective electrodes in stratum radiatum (SR) and stratum pyramidale (SP), while Ca2+ entry into neurons was induced with stimulus trains (20 Hz for 10 s) alternately delivered to SR and the alveus, respectively. The [Ca2+]o decreases recorded in SR in response to SR stimulation represented mainly presynaptic Ca2+ entry (Capre), while [Ca2+]o decreases recorded in SP in response to alvear stimulation were predominantly based on postsynaptic Ca2+ entry (Capost). Ethosuximide and trimethadione were ineffective in concentrations up to 1 mM. At 10 mM, they reduced Capost and, much less, also Capre. Nimodipine (25 microM) reduced Capost and, to a minor extent, Capre. omega-Agatoxin IVA (0.4-1 microM) and omega-contoxin MVIIC (1 microM) also reduced both Capre and Capost, but with a stronger action on Capre. omega-Conotoxin GVIA (3-8 microM) reduced Capost without effect on Capre. We conclude that during stimulus-induced, high-frequency neuronal activity Capost is carried by P/Q-, N-, and L- type channels and probably a further channel type different from these channels. Capre includes at least P/Q- and possibly L-type channels. N-type channels did not contribute to Capre in our experiments. Since ethosuximide and trimethadione were only effective in high concentrations, their action may be unspecific. Thus, T-type channels do not seem to play a major part in Ca2+ entry in this situation.

Four compounds were isolated from the fruit of cultivated Panax ginseng and identified as beta-sitosterol,20(R)-protopanaxatriol, daucosterine and 20(R)-ginsenoside-Rg3 on the basis of physicochemical constants and spectral evidences.

Electron capture processes in collisions of O6+ with ground state He and H2 are investigated using the two-centre atomic orbital close-coupling method. Total and state-selective one-electron capture cross sections are obtained for collision energies between 0.5 and 300 keV/u. The comparison with the available experimental state-selective capture data in the overlapping energy range (0.5–100 keV/u for O6++He and 0.5–8 keV/u for O6++H2) shows a good overall agreement. The polarization degrees of 3p 2P3/2–3s 2S1/2 radiation from O5+(3p 2P3/2) produced in O6++He and O6++H2 collisions are calculated from the magnetic substate-selective cross sections with inclusion of cascade contributions from higher n = 4 and n = 5 states. Good agreement is obtained with the experimental data available in the energy range 3–8 keV/u. Below ~10 keV/u, the polarization degrees of O5+(3p 2P3/2) in both collision systems exhibit an oscillatory structure and above this energy they steadily increase with the increase of collision energy, reaching the values of about 0.37 at 300 keV/u. The energy behaviour of the polarization degree of O5+(3p 2P3/2) in the O6++He collision system is determined almost exclusively by the direct electron capture to 3p0 and 3p1 states of O5+, while in the case of the O6++H2 collision system in the energy region below ~40 keV/u it is strongly affected by the cascade contributions from the 4l states, which are the dominant capture states in this system.

Standard microelectrode techniques were used to study the effects of isocorydine (Isoc) on potential characteristics of canine cardiac Purkinje fibers (PF) and ventricular myocardium (VM) in vitro. In PF, the action potential durations (APD), APD50, and APD90, were prolonged at 3 mumol.L-1 but shortened at 30 mumol.L-1 by Isoc. The action potential amplitude (APA) and the maximal upstroke velocity (Vmax) were decreased at 100 mumol.L-1. In VM, the action potential characteristics were changed by Isoc at above 30 mumol.L-1. APD50 was shortened by APD90 was prolonged. Vmax were decreased at 30 mumol.L-1. The effective refractory period (ERP) was prolonged by Isoc in PF and VM. The results suggest that Isoc may interfere with K+, Na+, and Ca2+ currents in myocardiac cell membrane at different concentrations.

The effects of metoclopramide (Met) on the action potential of rabbit sinus node cells and slow response action potential of guinea pig papillary muscles were studied with the intracellular microelectrodes. Met 10 mumol.L-1 prolonged the action potential duration at 90% repolarization (APD90) of SA node cell and sinus cycle length (SCL). Met 100 mumol.L-1 caused a decrease in action potential amplitude (APA), Vmax and the slope of phase 4 of action potential of SA node cell. APD90 and SCL were prolonged further. For slow response action potential induced by KCl (25 mmol.L-1), Met 100 mumol.L-1 produced a decrease in APA and depolarization rate. Met 10 mumol.L-1 began to suppress the spontaneous electrical activities induced by barium ion. These findings suggest that Met probably has the effect of blocking calcium inward current in myocardium.

The inhibition of the proteolytic activity of acrosin in human spermatozoa by butyl p-hydroxybenzoate was assessed by the gelatin substrate film method. Compared with a typical acrosin inhibitor, TLCK, the inhibitory activity of butyl p-hydroxybenzoate to acrosin was much more effective (20 times) than that of TLCK, proving that butyl p-hydroxybenzoate was a potent acrosin inhibitor. The effect of butyl p-hydroxybenzoate on membrane function of human spermatozoa was evaluated using a sperm-tail hypoosmotic swelling test and supravital stain method. A good correlation (r = 0.92) was observed between the % spermatozoa with normal membrane function and the % live spermatozoa after treatment of the spermatozoa with butyl p-hydroxybenzoate for 1 min, indicating that the death of spermatozoa caused by butyl p-hydroxybenzoate is probably due to impairment of sperm membrane function. Both the inhibitory effect on acrosin and the adverse effect on membrane function suggest that butyl p-hydroxybenzoate could be developed as a new vaginal contraceptive.

By using monoclonal anti-myoglobin antibodies to sensitize new immunospheres, serum myoglobin (SMb) was semi-quantitatively estimated with a rapid reverse passive latex agglutination (RPLA) test. Its clinical value in the early diagnosis of acute myocardial infarction (AMI) has been evaluated in 56 patients with AMI, 7 of them being observed serially. There are 92 serum specimens of AMI, of which 19 were within 12 hours after the onset of symptoms. Meanwhile, serum specimens of 72 non-AMI patients were observed with the same method. All the specimens above were also quantitated with radioimmunoassay (RIA) and the results were compared with those of RPLA. RPLA test was negative in the specimens below 100 ng/ml (81 specimens) and positive in those above 110 ng/ml (73 specimens). For specimens from 100 to 110 ng/ml, RPLA test could be either positive (9/10) or negative (1/10). This study confirms that RPLA test is a very sensitive indicator for acute myocardial infarction. It can yield a reliable semi-quantitative estimation of SMb within a few minutes. Because of its simplicity, rapidity and practicability. RPLA test is especially convenient for use in emergency room.

Two new natural products were isolated from the stems and leaves of Panax ginseng C.A. Meyer cultivated in Liaoning, China. Their structures were characterized as 20(R)-dammaran-3 beta, 6 alpha, 12 beta, 20, 25-pentol and 20(R)-dammaran-3 beta, 6 alpha, 12 beta, 20, 25-pentol-6-O-alpha-L-rhampyranosyl(1----2)-O-beta-D-gluc opy ranoside.

C60:LiF nanocomposite thin films were synthesized by physical vapor coevaporation. It is found that the nano-composite films are extremely conductive even at high LiF concentrations of up to 75wt% and that the films form Ohmic contacts with Al electrodes. IR measurements showed evidence of charge transfer from LiF to C60. Scanning electron microscope studies showed that C60:LiF (75wt%) nanocomposite forms uniform films. Compared with an archetypical tris(8-hydroxyquinolinato)alumina based device, OLEDs with the C60:LiF composite electron transport materials have lower driving voltages and higher power efficiencies.

A non-isentropic potential method on a S2 stream surface has been developed for the design and analysis of transonic compressors with shocks, in which the entropy increase across a shock may be directly calculated from the momentum equations in the divergence form. The numerical results show that the non-isentropic shock is weaker and placed one or two meches further upstream compared to the classical potential calculation, and is in good agreement with the experimental data.Copyright © 1988 by ASME

A method for solving various aerodynamic problems of transonic cascade design is developed, in which the coordinates equation is derived directly by inverting the stream function and the principal equation of the stream function. The corresponding “boundary conditions are obtained similarly. The coordinates equation has the same type property as that of the original equation and the only difference for various aerodynamic problems is the change of the boundary conditions on the cascade surfaces. Numerical results show that this unified method offers a useful tool for transonic cascade design.