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Biomedical subjects

N P Mertvetsov

Publications and source records attributed to N P Mertvetsov.

At least 73 records · Page 4Linked to original sources
PubMedDate not supplied

[Distribution of mineralocorticoid receptors in the kidney cells of rats with different levels of aldosterone in their bodies].

A metabolic method was applied to the study of the distribution of mineralocorticoid receptors in the kidney cells of rats at various aldosterone levels in the organism. A great number of binding sites of aldosterone in the cytoplasm and a low aldosterone-H3 binding by the nuclei of kidney cells was revealed in adrenalectomized rats, as well as in the animals kept under conditions of sodium load, when endogenous aldosterone was absent in the organism. A reduction of the number of binding sites in the cytoplasm and an increase of aldosterone-H3 binding in the nuclei was noted in the animals with a high content of the given hormone in the organism (sodium deficiency in food or aldosterone administration to the adrenalectomized animals). The difference in the hormone binding by the nuclei of the kidney cells of rats kept under conditions of sodium loading or deficiency corresponded to an even greater difference in the aldosterone binding by the chromatin proteins of such nuclei. It is supposed that an increased aldosterone concentration in the organism intensified the change from the cytoplasm and the accumulation of specific aldosterone-receptor complexes in the nuclei.

Adrenalectomy↗
PubMedDate not supplied

[Effect of L-thyroxine on the activity and isoenzymatic spectrum of liver hexokinase in intact and insulin-resistant rats].

Administration of L-thyroxine into intact rats caused a distinct increase in the activity of hexokinase in liver tissue. In the isoenzyme spectrum of hexokinase the activity of hexokinase II was increased significantly. After repeated administration of insulin, liver tissue cells lost their capacity to respond to the hormone administration by induction of hexokinase. Administration of L-thyroxine into animals caused a distinct increase in the hexokinase activity in liver tissue. In isoenzyme spectrum of hexokinase under effect of L-thyroxine a significant increase in the hexokinase II activity was also observed.

Agar↗
PubMedDate not supplied

[Effect of prolonged feeding of glucose to rats on the levels of sugar and insulin in the blood and the activity of key glycolysis enzymes in the liver].

A study was made of the effect of food with a high glucose content given to albino rats for a long time on blood sugar and insulin. Changes in the activity of hexokinase and pyruvickinase in the liver were also investigated. Food with a high glucose content given to rats for 90--100 days led to an increase in the blood sugar and insulin level. The activity of hexokinase and pyruvickinase rose markedly by the 40th--60th day of feeding, and fell to the initial level by the 80th--90th day. Thus, in case of a prolonged action of insulin on the organism as a result of prolonged stimulation of the insular apparatus of the pancreas by glucose there developed signs of peculiar insulin-resistance.

Animals↗
PubMedDate not supplied

[Angiogenin and its role in angiogenesis].

The review is devoted to angiogenin, one of the factors that induce formation of blood vessels, which is unique among them in that it is a ribonuclease. Consideration is given to the tertiary structure of human angiogenin; the catalytic and cell-receptor binding sites, their significance for angiogenic activity; the human angiogenin gene structure, chromosomal localization, and expression; the specificity of angiogenin as a ribonuclease and abolishment of protein synthesis; the nuclear localization of angiogenin in proliferating endothelial cells and its significance for angiogenic activity; angiogenin binding to a cell-surface actin as a plausible mechanism of inducing neovascularization (enhancement of plasminogen activation by actin with angiogenin, stimulation of the cell-associated proteolytic activity by angiogenin; promotion of the cultured cells invasiveness); modulation of mitogenic stimuli in endothelial, smooth muscle, and fibroblast cells by angiogenin. The importance of angiogenin as an adhesive molecule for endothelial and tumor cells is discussed too, as well as the modulation of tubular morphogenesis by bovine angiogenin, prevention of tumor growth in vivo by angiogenin antagonists, prospects of the use of angiogenin and angiogenin-encoding recombinant plasmids and vaccinia virus in therapeutic practice.

Actins↗
PubMedDate not supplied

[Introduction of the human recombinant angiogenin at the early stages of postnatal development inhibits the growth of mice].

We studied the influence of recombinant DNA containing the cloned angiogenin gene, plasmid DNA without angiogenin gene, and purified recombinant angiogenin injected to Tg8 mice at the age of two days on the body mass of 28- and 40-day old mice. The body mass of mice that were injected with the cloned angiogenin gene or purified angiogenin was less than in the control mice. The body mice of Tg8 mice injected with recombinant DNA containing the cloned angiogenin gene did not increase from day 2 to day 40, while in the mice with purified recombinant angiogenin and control mice it increased by 24 and 57%, respectively. These data suggest that the elevated level of angiogenin at the early developmental stages inhibits the increase of body mass. The effect we described as related, in al likelihood, to the known inhibitory effect of angiogenin on protein synthesis.

Animals↗
PubMedDate not supplied

[Binding of H3-aldosterone to cytoplasmic receptors of the kidney in various functional states of the organ target].

A study was made of the capacity of the cytoplasmic cell fraction of rat kidney to bind H3-aldosterone, depending on the level of Na uptake with food, and, consequently, on the intensity of aldosterone secretion by the adrenal glands. It was shown by Sketchard's method that there existed in the cytoplasmic fraction of the kidney cells of rats with a high and low level of aldosterone secretion two classes of receptors binding aldosterone with a different degree of affinity. The number of binding sites for aldosterone in the 1st class of receptors, more specific for mineralocorticoids in the animals with a low level of aldosterone secretion (Na loading), was double that in comparison with the animals with a high level of aldosterone (Na deficiency). It is supposed that an increased aldosterone concentration in the organism in Na deficiency increased the transport of the specific hormone-receptor complex from the cytoplasm into the nucleus.

Adrenal Cortex↗
PubMedDate not supplied

[Immunochemical characteristics of hydrocortisone induced and hydrocortisone non-induced rat liver tyrosine aminotransferase isoenzymes].

Two isoenzymes of tyrosine aminotransferase (induced and noninduced by hydrocortisone were isolated from rat liver tissue and subjected to chromatographic purification. Specific antibodies with high titer were obtained after immunization of rabbits by the inducible isoenzyme. The antigenic properties of the obtained tyrosine aminotransferase isoenzymes were compared after double immunodiffusion in agar and immunoelectrophoresis. The purified induced and non-induced isoenzymes were shown to possess both similar and different antigenic determinants. The data obtained suggest that differences in antigenic properties of the tyrosine aminotransferase isoenzymes reflect those variations in their structure, which are expressed as various thermostability, sensitivity to proteolytic enzymes and substrate specificity.

Animals↗
PubMedDate not supplied

[Molecular aspects of the action of insulin].

Molecular aspects of the insulin action in an organism are discussed. The following mechanisms of the hormone effect are considered: induction of the synthesis of glycolytic enzymes in cell-targets under effect of insulin; mechanisms of the insulin reception in cell-enzymes in cell-targets; the possible role of cyclic nucleotides as mediators in the effect of insulin in cell targets.

Adipose Tissue↗
PubMedDate not supplied

[The use of a molecular probe containing a specific cDNA consisting of bacteriophage M13 for detecting the hepatitis A virus in clinical specimens].

A probe was constructed containing a fragment of DNA replica of hepatitis A virus (HAV) RNA within bacteriophage M13 single-stranded DNA which allowed 10(-12) g of viral RNA to be tested. Hybridization of 32P-labeled probe with total RNA from 559 samples of blood, saliva, and urine from patients with viral hepatitis A revealed the presence of HAV RNA in 14% of the samples. In the 1st week of the jaundice period HAV RNA was detected in 40% (15 positive samples out of the 39 tested), in the 2nd week 26% (14 out of 54). HAV RNA was demonstrated in 20 out of 236 blood samples from subjects in a focus of HA outbreak. Six out of 9 subjects subsequently developing the disease were detected 7-10 days before the onset of the clinical symptoms. The proposed method may be useful for detection of HAV carriers in the latent period for their isolation in order to prevent further development of epidemic.

Bacteriophages↗
PubMedDate not supplied

[The study of protein-peptide hormones using genetic engineering methods (review of the literature)].

Use of genetic engineering technique in cloning and sequence assay of cDNA and genes coding for mammal protein and peptide hormones is reviewed. Recent data on molecular aspects of gene reorganization in some inherited disorders are considered involving analytical methods for evaluation of gene activity, especially of genes coding for peptide hormones. Sequence assay of mRNA coding for mammal proopiomelanocortins (precursor of adrenocorticotropic hormone), beta-lipotropic hormones of pituitary body, is discussed.

Amino Acid Sequence↗
PubMedDate not supplied

[Isolation of matrix RNA coding a tyrosine aminotransferase isoenzyme induced by hydrocortisone from rat liver polyribosomes].

Messenger RNA (mRNA) capable of coding hydrocortisone induced isoenzyme of tyrosineaminotransferase (TAT) was isolated and purified approximately 5000 times. Highly specific rabbit antibodies to the isoenzyme were obtained. Using these antibodies a specific antibody immunoadsorbent with a high capacity for specific binding to TAT was prepared. From total rat liver polyribosomes induced by hydrocortisone a specific fraction synthesising TAT was isolated by fractionation on the antibody immunoadsorbent. Affinity chromatography using poly(U)--Sephadex 4B allowed to isolate a poly(A)-containing RNA from this polyribosome fraction. The mRNA (15-16S) acts as a matrix in a cell-free protein synthesising system. The extent of purification of the mRNA was estimated by the synthesis of specific protein TAT in the cell-free system.

Animals↗