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Biomedical subjects

I Ia Kon'

Publications and source records attributed to I Ia Kon'.

63 records · Page 4Linked to original sources
PubMedDate not supplied

[Changes in the rat intestinal mucosa in hypervitaminosis A].

Administration of excess vitamin A to the growing male rats (50 000 IU of oily solution of retinol palmitate a day for 8 days) provoked a tendency toward a decrease in the number of goblet cells (of both absolute and relative number calculated per 500 cells of the epithelium) in the crypts and villi of the small intestinal mucosa, with this tendency being more marked in the inferior part of the intestine. At the same time administration of vitamin A excess increased the intensity of staining with alcyane blue of the secretion of the goblet cells, particularly on the apeces of the villi, which indicates the increased content of acid glycoconjugates in these cells. hypervitaminosis A was also accompanied by the intensification of infiltration with lymphocytes of the small intestinal epithelium and led to an increase in the number of plasma cells in the natural membrane of the villi. It is inferred that vitamin A excess produces an impairment in the program of enterocyte differentiation, characterized by both acceleration (an increase in the content of acid glycoconjugates in the goblet cells) and retardation (a decrease in the number of the goblet cells) of its individual aspects. At the same time hypervitaminosis A produces an adaptive-compensatory reaction on the part of the small intestinal mucosa, manifesting in activation of its infiltration with immunocompetent cells.

Animals↗
PubMedDate not supplied

[Enzymatic activity of glycoprotein catabolism in the organs of rats with hyper- and hypovitaminosis A].

Activities of glycosidases neuromanidase, alpha-L-fucosidase, beta-galactosidase and beta-N-acetylglucosaminidase were studied in rat small intestine and liver tissue under conditions of hyper- and hypovitaminosis A. Both excessive and insufficient administrations of vitamin A were accompanied by distinct alterations in activity of the enzymes studied in small intestine and (although less distinct) in liver tissue. The most significant dependence on the presence of vitamin A exhibited beta-galactosidase and especially alpha-L-fucosidase, activity of which was decreased in hypervitaminosis and increased in hypovitaminosis A. Activity of neuraminidase was usually slightly altered but its marked activation was noted in liver tissue under conditions of hypervitaminosis A. Vitamin A appears to participate in allosteric control of the glycosidase activity in small intestine and in catabolism of glycoproteins. The alterations of the enzymatic activity found in hyper- and hypovitaminosis A might be responsible for changes in composition of membrane glycoproteins and, hence, for the typical for vitamin A disbalance impairments in cellular growth and differentiation.

Acetylglucosaminidase↗
PubMedDate not supplied

[Mitochondrial and lysosomal membrane stability following administration of excessive doses of vitamin A in vivo].

Stability of mitochondrial and lysosomal membranes was studied in growing rats under conditions of hypervitaminosis A. The membrane stability was evaluated by the rate of solubilization of marker mitochondrial enzyme--malate dehydrogenase, and of lysosomal enzyme--beta-galactosidase, using incubation of the isolated organelles with gradually increasing concentrations of Triton X-100. High doses of vitamin A did not affect the total activity of the enzymes studied but distinctly increased the rate of malate dehydrogenase and beta-galactosidase solubilization, caused by Triton X-100, as compared with controls. This suggests the increase in sensitivity of the organelle membranes to the effect of Triton X-100 in the hypervitaminosis A, which is apparently related to pronounced impairment of the membrane structure.

Animals↗
PubMedDate not supplied

[Study of the thiamine supply of healthy school-age children and adolescents by examining transketolase activity and the TDP effect in the blood].

A modified method is described for determination of transketolase (TK) activity in the blood and the degree of its stimulation under the effect of exogenous thiamine diphosphate (TDP-effect). The method allows for an appreciable reduction of the time required for an analysis and to decrease 2-fold the blood volume necessary for the determination. With the use of the modification described 70 schoolchildren of three age groups (7-10, 11-13 and 14-15 years old) attending one of the Moscow non-specialized prolonged-day schools were examined. It was found that the magnitude of TDP-effect in the schoolchildren of all three groups was fairly similar (9.4, 7.7 and 6.9%, respectively) and was within normal (15%). Despite adequate thiamine status of all the group on the whole, in part of the schoolchildren (in 20% on the average) of each age group the magnitude of TDP-effect exceeded 15%. This pointed to inadequate supply with thiamine of these schoolchildren and to the necessity of taking appropriate measures aimed at preventing the clinically marked thiamine deficiency. The modified method suggested may be used during studies on thiamine supply of different population groups, particularly of the schoolchildren attending non-specialized schools.

Adolescent↗
PubMedDate not supplied

[Antioxidant effect of metallothioneins in acute bromobenzene poisoning in mice].

An increase in the content of malondialdehyde (MDA) and endogenous metallothioneins (MT) in the liver of mice 1 day after intraperitoneal injection of bromobenzene (0.5-2 g/kg) has been found. An exogenic zinc-MT polymer injected to mice decreases the basal and xenobiotic-induced MDA level in the liver and blood plasma and decreases the acute toxicity of bromobenzene. The mixture modelling zinc-MT composition (albumin, cysteine and zinc) possesses no such properties. A conclusion is made that the protective effect is specific for the MT structure and is induced by antioxidant properties of MT.

Acute Disease↗
PubMedDate not supplied

[Effect of retinol deficiency on the activity of phospholipase A lysosomal enzymes in rat testes].

In the testes homogenates of rats kept on a A-deficient ration and receiving additionally retinyl-acetate (control) and retinoic acid (experiment) the activity of the phospholipases A1 and A2, with 1-acyl-2(1-14C)-oleoyl-SN-glycero-3-galactosidase and acid phosphatase employed as a substrate, was investigated. In the testes of rats receiving retinyl-acetate the activity of the phospholipases A1 and A2 was greatly declining. An addition of retinyl to the testes homogenates of test rats contributed to re-establishing the activity of the phospholipases up to the control level. In the testes of rats receiving retinoic acid a reduced activity of the acid phosphatase and a rise of beta-galactosidase, as compared to their activity in controls was also demonstrable.

Acid Phosphatase↗
PubMedDate not supplied

[Lysosomal component in the mechanism of the toxic effect of sporofusarin].

The effect of Fusarium sporotrichiella v. sporotrichioides mycotoxin (sporofusarin) on the total and non-sedimentary supernatant activity of 13 marker-enzymes of subcellular particles (2 mitochondrial enzymes-cytochrome oxidase and malate dehydrogenase; 8 lysosomal enzymes -- acid phosphatase, acid RNAase, acid DNAase, arylsulphatases A and B, beta-N-acetylglucosaminidase, beta-glucuronidase, beta-galactosidase and beta-glucosidase; 2 microsomal enzymes -- glucose-6-phosphatase and acetylesterase; plasma membrane enzyme -- alkaline phosphatase) of the rat liver, kidney, spleen and bone-marrow was studied in in vivo experiments. The latter demonstrated that sporofusarin effects were characterized by a significant organ and organella specificity, viz. the toxin caused a sharply increased activity, mainly of lysosomes enzymes and labilization of the lysosomal membranes, primarily in the spleen and the bone-marrow. A conclusion is drawn that the discovered selective destructive action of sporofusarin on the lysosomes may be regarded as a new phenomenon that, possibly is directly related to the characterization of the mechanism responsible for a specific effect produced by sporofusarin.

Animals↗