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Biomedical subjects

A M Ugolev

Publications and source records attributed to A M Ugolev.

At least 109 records · Page 6Linked to original sources
PubMed1975

Substrate interactions on the intestinal mucosa: a concept for the regulation of intestinal digestion.

1. The hydrolysis of glycyl-L-leucine, glycyl-L-tyrosine, tributyrin, sucrose, maltose, soluble starch and alpha- and beta-glycerophosphates by everted segments of rat intestine was estimated separately or in combination. 2. A comparative study showed significant interaction between different substrates which affected their digestion. 3. Two types of interaction were identified: products of hydrolysis (1) affected the hydrolysis of homologous substances, e.g. methionine and alanine inhibited glycyl-L-leucine hydrolysis, maltose reduced glucoamylase (alpha-1,4-glucan glucohydrolase; EC 3-2-1-3) activity (intracatenary interactions); (2) interfered with the hydrolysis of a different group of substances, e.g. tributyrin inhibited dipeptidase (glycyl-L-leucine hydrolase; EC 3-4-3-2) and alkaline phosphatase (EC 3-1-3-1), glycyl-L-leucine interfered with the activity of the latter enzyme (intercatenary interactions). 4. Mechanisms of interactions were suggested by the results of a comparison of the extent of inhibition or activation of two enzymes (glycyl-L-leucine hydrolase and alkaline phosphatase) in situ in everted intestinal segments or after solubilization with papain or Triton X-100, and different treatments known to affect allosteric sites of these enzymes. 5. Tributyrin and dipeptides were found to act on alkaline phosphatase as allosteric regulators. A discontinuity of the Arrhenius plot suggested the existence of different enzyme conformations which were re-arranged by tributyrin. 6. Substrate interactions in digestion were found in adult rat, cat, rabbit and hen. Substantial differences were found between classes (Aves and Mammalia), orders (rodents, lagomorphs and carnivores) and between age-groups within an animal strain (in this instance, for the rat). 7. These interactions are thought to be involved in the co-ordination of digestion with intestinal absorption and to regulate the time and site of subsequent hydrolysis.

Alkaline Phosphatase↗
PubMed1975

Non-digestive functions of the intestinal hormones (enterines). New data and hypotheses based on experimental duodenectomy (Short review).

In cats and dogs, total duodenectomy with transplantation of the papilla Vateri into the jejunum and gastroenteroanastomosis has been shown to result in the so-called "duodenal deficiency syndrome" which is characterized, in the first phase, by cachexia of the animals occurring within 6 weeks after operation followed by obesity in the second phase. In contrast, animals with preserved by isolated duodenum do not exhibit pronounced changes in body weight as compared to intact controls. Consequently, it is suggested that intestinal hormones (enterines) not only exert gastrointestinal effects but also systemic ones. Thus, duodenectomy has been shown to lead to disturbances of lipid and protein metabolism, decreased secretory activities of the thyroid gland and the hypothalamus. Due to these findings, -- in addition to the even well-known intestinal hormones -- the existence of enterines with thyrotropic, lipotropic, hypothalamotropic, and appetite-regulating functions can be assumed which may make the duodenum act as an "abdominal hypophysis".

Ampulla of Vater↗
PubMed1974

Digestive and resorptive function of the small intestine in stressful situation.

The present study examines the effects of severe stress on digestive and resorptive functions of the small intestine. Transverse 20-minute acceleration (+10 Gx) results in an increase of invertase activity, particularly in distal parts of the small intestine. Although the activity of glycyl-l-leucine dipeptidase was changed, the fluctuations were less pronounced than those in invertase activity. Acceleration also produces rise in glucose accumulated in the intestinal mucosa and intensification of active carbohydrate transport. The displacement of the proximodistal gradient of invertase activity and carbohydrate resorption was significant. Dipeptidase and invertase activities in intestinal sacs and in tissue homogenates were depressed following exposure to 15-, 30- and 60-day hypokinetics. In distal parts the invertase activity was increased, and the resorptive function was enhanced. Following exposure to unusual gaseous atmospheres (hypoxic, hypercapnic and hyperoxic) there was an increase in active glucose transport over the entire length of the small intestine. Heat produces a decrease in invertase activity both in intact cells and homogenates. There were no pronounced changes in dipeptidase activity. Transport processes exhibited some variations.

Absorption↗