Allelic diversity at the primate Mhc-G locus: exon 3 bears stop codons in all Cercopithecinae sequences

The aim of this study was to determine whether bisaramil-an antiarrhythmic compound under clinical investigation-influences the reperfusion-induced arrhythmias and biochemical parameters characterizing occlusion-reperfusion-induced free-radical reactions. The left descending coronary artery (LAD) was occluded for 60 min in anaesthetized dogs followed by one hour of reperfusion. Blood samples were taken at different times of the occlusion and reperfusion for the determination of plasma concentration of malondialdehyde (MDA), reduced (GSH) and oxidized glutathione (GSSG); furthermore of the activity of catalase and superoxide dismutase (SOD). Free-radical generating capacity of polymorph neutrophil granulocytes (PMN) was also measured. At the end of the experiments heart tissue samples were excised from the injured areas and from the intact part of the left ventricular muscle. In tissues samples the concentrations of MDA and GSH and the activity of SOD were determined. Bisaramil was given as an i.v. bolus injection at a dose of 2 mg kg-1 several minutes prior to the end of LAD-occlusion; then the administration was repeated in the 30th minute of reperfusion. In the control group (10 dogs) ventricular fibrillation (VF) occurred in seven cases which resulted in death in three. In the bisaramil-treated group, however. VF was seen in three cases and no death was recorded. Bisaramil inhibited the elevation of the plasma concentration of MDA and GSSG during the reperfusion and abolished the decrease in the plasma concentration of GSH during the occlusion and reperfusion. The activity of SOD and catalase in plasma was much better preserved in the bisaramil-treated group then in the controls. Bisaramil significantly inhibited the increase of the superoxide-radical generating capacity of PMNs during the reperfusion. The data obtained from myocardial tissue samples supported the cardioprotective effect of bisaramil. The biochemical investigation of ischemic-reperfused myocardium showed that bisaramil promoted preservation of SOD-activity and of tissue glutathione. Results of this study clearly showed that bisaramil has a significant effect on ischemiareperfusion injury. Besides its inhibitory effects on ischaemia-reperfusion induced arrhythmias it has a special benefit in influencing free-radical mediated damage leading to better preservation of membranes and to limitations of irreversible cell injuries.     

Estimate of the intensity of gas filtration from a camouflet cavity under gas-dynamic blowout

The formation of a camouflet cavity under a sudden blowout of a compressed cold gas from a deepened source is considered. The intensity of gas outflow from the cavity by filtration in the pore space is estimated. It is shown that from the viewpoint of the useful work of plastic deformations and depth displacement of loose soil mass it is expedient to ensure optimum gas-discharge characteristics at low-density mass packing which corresponds to shallow depths of the energy source.Translated from Fizika Goreniya i Vzryva, Vol. 32, No. 4, pp. 134–140, July–August, 1996.     

Metrology-cybernetics-control: A new approach

As a science and as a special activity concerned with measurements, the science of metrology pursues a classical, orthodox purpose, mainly involving the measurement of physical quantities. The term “measurement” is now applied also to social, economic, medical, and other disciplines, including cybernetics and problems of management and control. Translated from Izmeritel'naya Tekhnika, No. 7, pp. 17–20, July, 1996.     

Linearization of Drug Delivery from Sustained-Release Dosage Forms, Synthetic Gel Systems

A linear, apparent zero-order, in vitro release profile may be approximated from triple-pressed tablets using synthetic gum systems in the first and second press coats. This is coupled with varying concentrations of the actives (Melperone HCl. Diethylpropion HCl, and Dyphylline) in the core and press coats. The approximately linear release function obtained from these tablet systems is in stark contrast to a supposedly prolonged release tablet (comparative formulation) from the literature, which actually releases by the square root of time function characteristic of diffusion control. Addition of a placebo press coat to the outside of the synthetic gum systems simply increases the lag times for release (while the placebo coat is undergoing hydration, etc.). The linearity following the lag is reminiscent of saturation kinetics. Results suggest that the almost linear release profile is a function of the concentration of the various layers (core first and second press coats) coupled with the gelation characteristics of the synthetic gums. This zero order release does not hold for the systems of the comparative formulation taken from the patent literature.     

Bit error simulation for π/4 DQPSK mobile radio communicationsusing two-ray and measurement-based impulse response models

An accurate software/hardware bit-by-bit error simulator for mobile radio communications is described. Simulation results in indoor and outdoor channels are compared with theoretical results. Bit error rate (BER) results in simulated frequency-selective fading channels generated by several channel models such as two-ray, constant amplitude, and simulated indoor radio channel impulse models (SIRCIMs) are presented. It is shown that BER is not only dependent on the RMS delay spread, but also on the distribution of temporal and spatial multipath components in local areas. An important result is that a two-ray Rayleigh fading model is a poor fit for indoor wireless channels and, if used, can underestimate the BER by orders of magnitude. A real-time bit error simulation of video transmission using the bit-by-bit error simulator is described. The simulator, called BERSIM, is shown to be a useful tool for evaluating emerging data transmission products for digital mobile communications     

Creep deformation of induction pressure welded 2·25Cr-1Mo steel

In this paper, experimental results involving the effect of stress and temperature on creep behaviour of induction pressure welded (IPW) 2·25Cr-1Mo steel are presented. Creep rupture tests were conducted at 550–700°C in steps of 50°C over a stress range of 112·5–180 MPa. Above 650°C failure of the specimen was enhanced due to the microstructural instability. Failure in the specimens occurred invariably in the heat affected zones (HAZ), and the fracture surfaces indicated ductile failure.     

Platelet-activating factor and the vascular effects of zymosan in rats

Platelet-activating factor (PAF; 2.5 micrograms/kg) injected in the tail vein of anaesthetized rats increased the vascular permeability of the duodenum, paws, skin and muscles, as measured by the extravasation of 125I-labelled albumin. It did not affect the permeability of the lungs or the presence of labelled albumin in the liver and spleen. The effects of PAF were dose dependently inhibited by WEB 2086 (ID50: 1.39 to 2.09 mg/kg) and SM-12502 (ID50: 7.17 to 8.36 mg/kg). Zymosan, an activator of the alternative complement pathway (10 or 16 mg/kg), induced protein extravasation in the lungs, duodenum, paws and skin, and the accumulation of labelled albumin in the liver. The effects of zymosan on the duodenum and liver were dose dependently inhibited by WEB-2086 and SM-12502. Both PAF antagonists increased the effects of zymosan in the paws but they did not affect protein extravasation in the lungs. The hypotensive effect of PAF (0.5 micrograms/kg) was inhibited by WEB 2086 (ID50: 1.21 mg/kg) and SM-12502 (ID50: 13.4 mg/kg). Both PAF antagonists reduced the hypotensive effects of zymosan (4 or 16 mg/kg) with a similar relative inhibitory potency. PAF is the major mediator involved in the hypotensive effect of zymosan but plays only a minor role in the permeability-enhancing effect of zymosan, mostly in the splanchnic area.