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Biomedical subjects

V A Isachenkov

Publications and source records attributed to V A Isachenkov.

At least 37 records · Page 2Linked to original sources
PubMed1977

[Properties of human creatine kinase isoenzymes].

Properties of human creatine kinase isoenzymes (MM, MB and BB) are investigated. The most pronounced differences in properties of these isoenzymes are found under their urea inactivation, heat denaturation and the inhibition by rabbit antisera to isoenzymes. Differences in values of the Mikhaelis constant and substrate and pH dependencies are much less pronounced. The presence of ADP stabilizes creatine kinase isoenzymes under conditions of urea and heat inactivation. Properties of hybrid MB isoenzymes are found to be intermediate with respect to MM and BB isoenzymes. A mode of the interaction of M and B subunits in dimeric molecules of creatine kinase isoenzymes is discussed.

Adenosine Diphosphate↗
PubMed1976

[Interrelationship of the pineal body with the hypothalamo-hypophyseal complex. II. The effect of melatonin on the incorporation of H3-leucine in the anterior and medial hypothalamic nuclei of pinealectomized blinded rats].

A study was made of the effect of low doses of melatonin on the H3-leucine incorporation into the supraoptic, paraventricular, ventro-medial, and arcuate nuclei of the hypothalamus. Sexually mature blinded pinealectomized female rats were used in these experiments. Melatonin administered in a dose of 10 mug at 11 a.m. for 9 days inhibited the biosynthetic potential of the mentioned hypothalamic nuclei enhanced by extirpation of the epiphysis. Administration of melatonin at 11 p.m. in the same doses produced no effect on leucine incorporation.

Animals↗
PubMedDate not supplied

[The relationship between the pineal gland and the hypothalamo-hypophyseal complex. I. The effect of pinealectomy, binding and continuous illumination on H3-leucine incorporation in the nucleus of the anterior, middle and posterior hypothalamus of prepubertal and sexually mature rats].

Autoradiography was applied to the study of the effect of extirpation of the epiphysis in rats on the level of H3-leucine incorporation by the neurons of 8 couples of the nuclei localized in the anterior, middle and posterior portions of the hypothalamus. Experiments were conducted on female animals of the prepubertal and reproductive age. Pinealectomy was combined with binding (a factor intensifying the physiological status of the epiphysis) and continuous illumination (a factor inhibiting the function of this gland). In the blinded prepubertal rats pinealectomy enhanced the H3-leucine incorporation into the supraoptic nucleus by 38%, into the paraventricular--by 26%, into the dorsomedial--by 61%, into the premammillary dorsal--by 58%, into the ventro-medial--by 40%, into the premammillary ventral--by 36%, and into the anterior hypothalamic--by 26%. In mature rats this index exceeded, after pinealectomy, such in the sham-operated animals (control) in the supraoptic nucleus by 48%, in the paraventral--by 40%, in the premamillary ventral--by 80%, in the arcuate--by 48%, in the premammillary dorsal--by 35%, in the ventro-medial--by 29%, and in the dorso-medial--by 26%. Continuous illumination reduced the stimulating influence of pinealectomy on the H3-leucine incorporation into the neurons of the premammillary and the arcuate nuclei, without changing the difference between the experiment and control in the macrocellular nuclei. On the whole, the results obtained permit a conclusion to be drawn on tonic inhibition by the epiphysis of the extensive hypothalamic zones.

Animals↗
PubMedDate not supplied

[Metabolism of sex steroid hormones in neuroendocrine organs. I. In vitro androgen metabolism in the hypophyses and epiphyses of rats during the puberal period].

Metabolism of tritium-labeled testosterone, delta4-androstane-3, 17-dion, dihydrotestosterone. 5alpha-androstane-3alpha, 17beta-diod and 5alpha-androstane-3beta, 17beta-dion by the isolated hypophyses and epiphyses of male and female 30-day rats was studied. The glands were incubated in Eagle's medium containing the mentioned androgens with the concentration of 1-2.10(-8) M for 90 min at 37 degrees C. As revealed, restoration of testosterone and delta4 androstane-3, 17-dion by 5alpha-reductase occurred in the epiphyses and hypophyses; under conditions of incubation androgen hydroxylation was realized only in the 3alpha- and 17beta-positions. Organ and sexual specificity of the androgen metabolism in the hypophyses and the epiphyses was quantitative in character: the metabolism level of all the androgens was greater in female rats than in the male both in the hypophysis and in the epiphyses; the activity of 5-reductase was lower in the epiphyses of animals of the both sexes than in the hypophyses. It appeared that in the process of biotransformation androgens in the organs under study served as precursors of the polar unidentified metabolites poorly retained by the tissues and eliminated from the organs into the incubation medium during the incubation.

15-Oxoprostaglandin 13-Reductase↗
PubMedDate not supplied

[Simple and rapid heterologous method of radioimmunochemical determination of luteinizing hormone in the blood serum of rats. 1. Basic principles of the method].

Possibilities of creation of a radioimmunochemical method (RICM) of determination of the luteinising hormone (LH) were studied. The method is based on the application in the binding system of a water-insoluble immunosorbent obtained by copolymerization of antisera with isobutyl ester of chlorocarbonic acid. The antisera were obtained by immunization of rabbits with a highly-purified LH isolated from sheep hypophyses. The method is rapid and precise, and is carried out in a single stage. Significant results of RICM in the LH determination can be obtained with the minimal two-hour incubation time. Using different amounts of the immunosorbent in the reaction mixture with the same indicator dose of I125-LH it is possible to vary the method sensitivity (from 0.05 to 5 ng/test).

Animals↗
PubMedDate not supplied

[Immunosorption method of urokinase determination].

An immunosorption procedure is developed for quantitative estimation of plasminogen activator of the urokinase type in human blood serum. The procedure involved sorption of urokinase from blood serum using polyclonal antibodies to the enzyme as a sorbent at the first step of the assay. Concentration of the immunoreactive urokinase in a preparation correlated with the absorbed fraction of standard urokinase added into the sample at the second step after washing of the sorbent. The residual fibrinolytic activity of the standard dose was detected in fibrin-agar gel. Results of the assay were not altered in presence of high molecular (bovine blood serum, soy bean inhibitor of trypsin) and low molecular inhibitors of urokinase (benzamidine, arginine, epsilon-aminocapronic acid). Sensitivity of the assay constituted 0.05 IU/sample (2.5 IU/ml, 0.25 ng/sample) and might be increased by a decimal order after addition of plasminogen into fibrin-agar gel. Content of urokinase in blood serum of healthy men (21-48 years old) was equal to 166 +/- 8.9 IU/ml with individual variations from 107 to 260 IU/ml.

Blood Proteins↗
PubMedDate not supplied

[Interaction of plasminogen activator of urokinase type with human serum].

Effects of blood serum on u-PA (EC 3.4.21.31) fibrinolytic activity were studied. After incubation for one hour at 37 degrees of the enzyme with human blood serum (55-145 IU/ml of blood serum) the enzymatic activity was completely inhibited. At the same time, amido-lytic activity of u-PA, estimated with low molecular substance S2444 as a substrate, was maintained in presence of blood serum. Blood serum inhibitors did not exhibit the specific affinity to u-PA. Serine proteases (trypsin, chymotrypsin and plasmin) competed with u-PA at equimolar concentrations. These inhibitors were inactivated after blood serum preincubation with primary amines methylamine, ethylamine, putrescine, spermidine and spermine (0.1-10 mM). The u-PA-inhibitor complexes were not dissociated in presence of 2.5 mM sodium dodecylsulfate. Trypsin-albumin copolymer bound specifically the blood serum u-PA inhibitors and the fraction adsorbed was electrophoretically characterized as a protein with molecular mass of 185 kDa.

Benzamidines↗
PubMedDate not supplied

[Relationship between the pineal body and the hypothalamo-hypophyseal complex. 3. Possible role of LH releasing hormone in the hypothalamo-epiphyseal feedback].

The presence of immunoreactive LH-releasing hormone (LH-RH) was revealed in the epiphysis of rats by radioimmunochemical method. The content of this hormone displayed circadian variations: it was maximum at 6 p.m. and minimum at 6 a.m. Intravenous injection of synthetic LG-RH to infantile and sexually mature rats of both sexes induced in the epiphysis the activity of hydroxyindol-O-methyl transpherase (HIOMT), the key enzyme of melatonin synthesis. Increased activity of this enzyme in the epiphysis persisted for at least 5 hours after the administration of LH-RH. HIOMT activation is preceded by a rapid fall (in 5 minutes) of cyclic adenosine-3', 5'-monophosphate in the epiphysis. The data obtained permitted to suppose that feed-back of the hypothalamus with the epiphysis could be realized with the aid of LH-RH.

Acetylserotonin O-Methyltransferase↗
PubMedDate not supplied

[Interrelationship between the pineal gland and the hypothalamo-hypophyseal complex. IV. Effect of pinealectomy on the luteinizing function of the rat pituitary].

The effect of pinealectomy on the luteinizing function of the hypophysis was studied in sexually mature rats. Following pinealectomy or sham operation rats were blinded in one experimental series, and both blinded and ovariectomized--in another series. Blood LH was determined radioimmunologically with hard-phase immunosorbent produced from antiserum. Pinealectomy does not alter the basic blood LH concentration in the blinded male and female animals. In comparison with the sham operated rats, LH mobilization from the hypophysis was elevated in the blinded ovariectomized rats with removed pineal gland under the action of the maximal LH-releasing hormone dose (200 ng per rat). In comparison with the initial, the hormone concentration increased in control group by 189%, and in the pinealectomized--by 301%. Pinealectomy intensified the autopotentiating action of the LH-releasing hormone (in repeated administration in 60 min) to 1119%, whereas in control rats an increase of the blood LH in response to the repeated adminstration of the LH-releasing hormone constituted 730% in comparison with the initial level. Pinealectomy decreased the inhibitory action of actidion on the autopotentiating effect of the LH-releasing hormone. Besides, pinealectomy accelerated the I125-LH elimination from the circulation in the blinded female rats = 7 min). It is supposed that LH biosynthesis was more active in the hypophysis of pinealectomized rats.

Animals↗