Sensory distinction between H-2b and H-2bm1 mutant mice.

Genetic polymorphism in the H-2:Qa:Tla region of chromosome 17 is associated with constitutive variation of bodily odor phenotypes which permit individual olfactory recognition among mice. To determine whether known genes in the H-2:Qa:Tla complex are concerned in the constitution of odor phenotypes, mice were tested for their ability to sense a difference between the B6/By (H-2b) and congeneic B6.C-H-2bm1 strains, which differ genetically by mutation of the H-2K gene. As in previous studies of the sensory discrimination of H-2:Qa:Tla phenotypes, mice were trained by reward in a Y maze to distinguish the odors of urine samples, and the successful distinctions of B6/By from B6.C-H-2bm1 were confirmed by transfer of training, without reward, to coded samples of urine from genetically equivalent urine donor mice which the trained mice had not previously encountered. Cosegregation of odor phenotype with H-2b and H-2bm1 was demonstrated by transfer of training to typed H-2b and H-2bm1 homozygous segregants of F2 generations of appropriate crosses. Although it is not excluded that the differences in odor phenotype which distinguish H-2b and H-2bm1 mice are directly related to the structure of the H-2b and H-2bm1 products, it is equally possible that H-2-related odor phenotypes arise from effects of H-2 genetic variation on metabolic pathways either directly, or indirectly through developmental polymorphism.     

Effect of nibentan on dispersion of repolarization of ventricular myocardium in the rabbit

Among factors determining development of polymorphic ventricular tachycardia torsades de pointes under influence of class III antiarrhythmic drugs great value is attributed to enhanced heterogeneity of repolarization of ventricular myocardium which can cause functional conduction blocks and development of re-entry of excitation. In this work with the help of optical mapping of electrical activity of the heart we investigated effect of nibentan (0.3 and 1 mM) on chronotopography of repolarization of epicardial surface of ventricles of isolated after Langendorf rabbit heart (n=5). For assessment of heterogeneity of repolarization we measured the following parameters: standard deviation of mean action potential duration (APDm) along mapped region (SD-APD), dispersion index (DI=1000 SD-APDm), maximal dispersion (Dmax=APDmax-APDmin). Nibentan in concentrations 0.3 and 1 mM increased APD at the level of 90% repolarization (APD90%) from 231 +/- 12 to 277 +/- 7 ms (p < 0.05) 318 +/- 7 ms (p < 0.001), respectively, but in concentration 1 mM it practically did not affect parameters of heterogeneity of repolarization (SD-APD: from 4.4 +/- 0.9 to 5.7 +/- 1.1 ms, p=0.4; DI: from 19.1 +/- 4.2 to 18.0+3.5, p=0.8; Dmax: from 16.6 +/- 2.5 to 24.8 +/- 4.3 ms, < 0.05). These results show that nibentan in the range of clinically used doses does not effect heterogeneity of ventricular myocardium. This can explain low proarrhythmic effect of nibentan.     

Results of medical studies in relation to the program of the second space flight on the orbital complex "Mir"

In 1987, the USSR cosmonauts Y. V. Romanenko (326 days), A. I. Laveikin (approximately 176 days), and A. P. Alexandrov (approximately 160 days) made a space mission on Mir. (A. I. Laveikin showed specific cardiovascular responses to exercise tests and was therefore replaced with A. P. Alexandrov). The most important medical result of this mission was that Yu. V. Romanenko, who remained in orbit for 3 months longer than anyone before, working intensively, did not exhibit any changes that were qualitatively different from those observed in previous long-duration space flights. The health status and work performance of other crewmembers were also good, although each of them showed individual responses. The postflight recovery period went smooth.     

Economic effectiveness of conservative and surgical methods of treatment of duodenal ulcer in young patients

The work evaluates the results of treatment of duodenal ulcer in 152 young patients. The state's financial losses connected with their treatment by various methods are counted up. Prolonged nonoperative treatment was applied in 52 patients (group I), organ-preserving operations were carried out in 100 patients (group II). Group I patients felt much worse, most of them suffered from annual recurrences of the disease, 21% underwent various operative interventions later due to the development of complications. Good and excellent results were recorded in 86% of group II patients. It was established that not only are the clinical results better in group II patients, but the economical losses in timely performance of organ-preserving operations are half those in prolonged nonoperative therapy.     

Biomedical Aspects of Cardiac Massage in Experiments and Clinical Practice

Despite current successes in modern cardiology and heart surgery, the problem of restoring and maintaining cardiac function in cases of sudden arrest or ventricular insufficiency is still urgent. Different methods of mechanically assisting the heart and replacing its pumping function exist, and direct mechanical cardiac massage (DMCM) is one of the more important. Experimental results with dogs and calves on 2- to 4-h DMCM, cardiac massage lasting for up to 48 h, subsequent restoration of cardiac activity, and cardiac massage during experimentally induced myocardial infarction permitted clinical application in patients with myocardial infarction complicated by ventricular fibrillation. DMCM also permits extension of the possibilities of obtaining and transplanting donor organs. It is one of the variants for solving the problem of total and partial replacement of the pump function of the heart, and now makes it possible to solve some important problems in transplantation and cardiac resuscitation.