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Biomedical subjects

A M Ugolev

Publications and source records attributed to A M Ugolev.

At least 37 records · Page 2Linked to original sources
PubMed1991

[The hydrolases of the mucosal, submucosal and muscular layers of the small intestine and their functions].

Proceeding from the newly obtained evidence on the distribution of digestive enzymes in mucosal, submucosal and muscular layers of the small intestine in rats, a hypothesis has been formulated: in addition to the enterocyte enzyme complex forming the epithelial barrier, there seems to exist a postepithelial barrier formed by the enzymes localized in subepithelial structures. The efficiency of this second barrier was manifested by the study of the peptide hydrolysis and transport using everted intact and de-epithelialized intestinal sacs.

Animals↗
PubMed1990

Localization of peptide hydrolysis in the enterocyte and the transport mechanisms of apical membrane.

1. The absence of the effect of anoxia on the hydrolysis rate of a number of dipeptides and one tripeptide by the intact and homogenized mucosa of the small intestine in different mammals (rat, mouse and guinea pig) has been demonstrated. 2. It has been shown that in rats anoxia inhibits intestinal transport both of free glycine and glycine formed during the hydrolysis of Gly-Leu, Leu-Gly, Gly-Pro but not Pro-Gly. 3. Data obtained using the anoxic criterion suggest that the systems of membrane hydrolysis of peptides with the subsequent absorption of released amino acids presents a dominant mechanism of protein assimilation under normal physiological conditions. 4. However, they do not exclude the possibility of the transport of peptides across the apical membrane of enterocytes.

Absorption↗
PubMed1990

Two-channel transporter versus a single-channel Na+-dependent transporter for glucose and amino acids in rat and turtle.

Conditions in rat and turtle small intestine tissue where glucose and glycine transport are inhibited while glucose-induced Na+ transport is preserved are described. The generally accepted model for the Na(+)-dependent transporter (a single channel for the Na+ and nutrient) does not account for the data obtained from an analysis of the interaction between the transport of glucose, glycine, and Na+ at different temperatures and the effect of inhibitors on these processes. The phenomenon of uncoupling of Na+ and nutrient transport can best be described by a two-channel model with a gate mechanism. According to this model, the Na(+)-dependent transporter has at least two channels: one for Na+ and another for nutrients. The model provides for the passage of Na+ in both directions along a channel opened by glucose, and accounts for changes in the stoichiometric ratio of Na+: glucose transport. Experiments are reported that confirm these theoretical predictions.

Amino Acids↗
PubMed1990

[Proteolytic activities of colonic mucosa].

The large intestine of human and dog contains considerable activities of various aminopeptidases and genuine dipeptidases. Furthermore, a dipeptidase is described, which is independant in respect to the C-terminal configuration of the peptide. This dipeptidase is an intrinsic membrane protein. The physiological significance of these enzymes is discussed.

Aminopeptidases↗
PubMed1987

[Canalicular system of enterocytes at rest and its changes during lipid absorption].

A study was made of the structural changes in different organoids of enterocytes of the rat small intestine at "rest" and during lipid absorption using ultrathin sections, impregnation with Ur-Pb-Cu, and continuous impregnation with OsO4. With the latter technique a specific canalicular system was found in the enterocytes, which we failed to observe on ultrathin sections. During lipid absorption the canalicular system underwent fragmentation. The vesicules on the trans-surface of the Golgi apparatus were enlarged, and the number of flattened cisterns was significantly lower. The changes in cellular organoids and their interrelations observed in the present study support the earlier hypothesis of the resynthesis of triglycerides within the enterocytes, the formation of chylomicrons and their transfer into the intercellular space.

Animals↗