Biomedical subjects
Publications and source records attributed to L M Mikhneva.
The "middle molecules", endotoxins of peptide nature appearing in biological fluids in several diseases, cause the disorder of many regulatory processes, suppress the functions of blood cells, affect the transport characteristics of cell membranes. The review covers different aspects of formation, structure and numerous biological effects of "middle molecules", including the molecular mechanism of their biological action.
Empirical energy calculations were used to determine all low-energy conformations of vasoactive pentapeptide Ala-Arg-Pro-Ala-Lys, thereby three most stable conformations were distinguished. Biological testing of conformationally restricted analogs allowed to delineate the most probable "biologically active" conformation of the molecule.
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The authors examined the soluble proteins of the brain frontal lobes in the newborn with trisomias of the 13th, 18th, and 21st chromosomes (Down's, Patau's, and Edwards' syndromes). The examinations were carried out on autopsy material (the post-mortem period not exceeding 24 hours) by the method of disc electrophoresis in polyacrylamide gel. The brain tissue was taken from 17 newborn infants with Down's syndrome; 9 infants with Patau's syndrome; and 7 infants with Edwards' syndrome. For the control the brain of 21 newborn infants without defects of the CNS development (the death cause being analogous) was taken. In all the syndromes studied diversely directed but relatively specific shifts were revealed on the proteinograms. It was the albumin section which appeared to be the most sensitive to the chromosomal pathology: in cases of Down's and Patau's syndromes the protein content in it was reduced, whereas in cases of Edwards' syndrome it was increased. In the latter syndrome the relative amount of neuronines S-5 and S-6, and in Patau's syndrome the amount of neuronine S-6 were lowered, this lowering being statistically significantly. In all the trisomias a tendency to a diminution of the zone of the acidic neurospecific cerebral proteins was noted. This is, possibly, due to the lower level of the CNS functional activity in chromosomal pathologies.
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It has been demonstrated that the plasma ratio of free and protein-bound corticosterone depends on the hypoxic degree. After two-hour hypoxia at an altitude of 10,000 m the trained and untrained animals exhibit a similar content of the free hormone (21%), with the content of total corticosterone being significantly lower in the trained rats. A study of variations in the content of free corticosterone in rats exposed to hypoxia for 20, 45 and 120 min and ACTH administration during the same time intervals has shown that the binding capacity of transcortine changes 45 min after the beginning of hypoxia.
Blood plasma proteins and soluble proteins from brain lobus frontalis of patients with mongolism were studied using polyacrylamide gel disc electrophoresis. A decrease in content of albumins, proteins of Gc system, transferrine, fast posttransferrines and an increase in amount of immunoglobulin proteins as well as of alpha 2-macroglobulin were observed in the preparations of blood plasma proteins. These alterations were apparently determined by impairments in functions of protein-synthesizing systems. Content of four different protein fractions was altered as shown by brain proteinogramms.
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