Biomedical subjects
Publications and source records attributed to V V Egorova.
The activity of digestive enzymes was reduced both in the small intestine mucosal layer and in the postepithelial ones. The reduction was due to sodium nitrate administration and was more obvious in the rats fed with proteins. The response of the enzyme systems of the liver and kidney was heterogeneous.
Diagnostic value of protein C measurements was investigated in 159 surgical patients with diseases of the liver, great vessels, and wound infection. Protein C antigen was detected by ELISA with specific antibodies to protein C. The changes of protein C antigenic activity correlated with severity of hepatic disorders. Inhibition of protein C synthetic activity went on in parallel with a fall in pseudocholine esterase concentrations. This suggests feasibility of protein C measurements for examination of protein production by the liver. Characteristics and location of the lesions in great vessels were also related to protein C antigen levels. The fall in this antigen quantity was observed in patients with purulent wound infection. The greater the fall, the more serious the patient's condition became.
The effects of fasting and immobilization manifests itself in changes of the enzymes activity in the stomach, duodenum, jejunum, ileum, colon as well as in the liver, spleen, kidneys. In these conditions, the protective function is primarily fulfilled by the enzyme systems of the non-digestive organs whereas the enzymatic intestinal barrier is less obvious.
A reduced activity of cytosol dipeptidases was revealed both in epithelial and subepithelial layers of the small intestine against the background of protein deprivation in adult and maturing rats. The latters' enzyme systems of the small intestine and kidneys' layers proved to be particularly sensitive to protein deprivation. The disturbance of the digestive-barrier functions provides favourable conditions for penetration of foreign protein and peptide substances into the organism's inner milieu which can be dangerous for a maturing organism.
The large intestine was found to reveal an obvious activity of various aminopeptidases and genuine dipeptidases in dogs and in humans. A dipeptidase was found specific by its independence of the C-terminal configuration of the peptide. This peptidase in an intrinsic membrane protein. Physiological significance of these enzymes is discussed.
Administration of nitrates to pregnant rats induced disorder in maturation and hormonal regulation of enzymes prompting the digestion of the main nutrients in the small intestine of suckling rats. Essential changes were also found under these conditions in activity of the liver and kidney enzymes maintaining the barrier and protective functions.
In suckling rats whose mothers had had an immobilisation stress or been injected HC and T4 at the last day of their pregnancy, the sucrase induction decreased in the small intestine, if the HC was injected on the 10th day of life. The hormone injection to 1-day suckling rats did not affect the induction. These effects seem to be exerted not by the direct permeation of hormone from mother to litter but to be mediated rather by a special factor "stressin". The latter is transferred from mother to litter and decreases the sensitivity of intestinal enzymes to exogenous HC, thus exerting an antistressor effect.
The activity of the small intestine's peptide hydrolases is higher in 1-day old rats than in adult rats, whereas levels of activity of alkaline phosphatase and diglycyl glycine peptidase do not differ significantly in these two groups of the rats. Our own data on carbohydrases corroborate other authors' evidence and reveals that activities of lactase, sucrase and maltase are either absent or very low in the first days of life and sharply increase by the third week of postnatal development. Adaptive changes of regulatory properties of lactase and alkaline phosphatase are revealed.
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Ageing was shown to be accompanied by changes of the activity levels of the small intestine's carbohydrases, dipeptidases, and alkaline phosphatases. The changes occurred both under normal conditions and after operations on the small intestine. In ageing, the small intestine's capacity for the homeomorphosis decreases irrespective of either increase or decrease in the functional loading. The age involution of the gastrointestinal tract is followed by disturbances not only in hydrolytic processes but in transport those as well: particularly deceleration of glucose accumulation in preparations of the rat intestine mucose. Regulatory properties of some enzymes were changed, too, in old rats.
A wide range of digestive enzymes with different cellular location (membrane, intracellular, Lysosomal) was determined in gastrointestinal organs (stomach, duodenum, jejunum, ileum, colon) as well as in undigestive organs (liver, kidney, spleen) in normal conditions and in altered functional states (fasting, refeeding). High levels of peptidase activity was noted in undigestive organs and the colon as compared to that in the small intestine. Adaptive responses were (revealed not only for a number of membrane enzymes but also for intracellular ones including those in undigestive organs.
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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.
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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.
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