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Biomedical subjects

N N Lebedev

Publications and source records attributed to N N Lebedev.

At least 19 recordsLinked to original sources
PubMed2001

[Acid producing function of the stomach in patients with duodenal ulcer and diabetes mellitus].

We studied gastric secretion in submaximal and maximal histamine and pentagastrin tests, computer-assisted pH-metry, chromogastroscopy and chromoduodenoscopy in 205 patients with duodenal ulcer (DU) and diabetes mellitus (DM). DU patients with DM type I had low acid gastric secretion in the stimulated phase, an excitable type of gastric secretion, continuous acid-formation of low intensity, subcompensated acid-neutralizing function of the antral portion of the stomach, normoacidic state. DU patients with DM type II had low fasting acid gastric secretion, an inhibitory type of gastric secretion, normal acid-formation, compensated acid-neutralizing function of the antral portion of the stomach, hypoacidic state.

Adult↗
PubMed1998

[The treatment of peptic ulcers of gastrointestinal anastomoses].

Peptic ulcers of gastroenterostomies are a serious complication after resection of the stomach or gastrojejunostomy. Their appearance is always associated with the presence of considerable production of hydrochloric acid in the stomach, while the primary operations are performed, as a rule, for chronic ulcers of the duodenum. Choice of an adequate kind of treatment of these patients still remains an actual problem. The authors have obtained convincing data of good results of conservative treatment of patients with peptic ulcer of the anastomosis. However, surgery is considered to be the main method of treatment of this category of patients. Its success depends upon the correct detection of causes of the disease and use of the pathogenetically substantiated surgical interventions aimed at eradication of etiological factors.

Adult↗
PubMed1997

[The effect of a paravertebral novocaine block on acid formation in the stomach].

The dependence of acid-formation in the stomach on the blockade of sympathetic innervation of the acid-formation area was investigated in 38 patients in whom the paravertebral novocaine blockade was made at the ThVII-ThIX level in order to cup off the pain syndrome. The control group included 7 patients without diseases of the organs of the hepato-pancreatico-duodenal zone. This blockade was found to sharply increase the basal acid-formation in healthy people. In patients with the high acid-formation it leads to greater elevation of acidity. It was shown that the disturbed functional balance between two parts of the vegetative nervous system responsible for the acid-formation function of the stomach was one of the causes of higher acid formation in patients with peptic ulcer of the gastroenterostomy and with chronic ulcer of the duodenum. It seems to be reasonable to investigate disturbances of the function of sympathetic innervation of the acid-formation area of the stomach for determining the optimum volume of surgical interventions in such patients.

Anesthetics, Local↗
PubMed1992

[The hemostatic effect of vagotomy in acute gastroduodenal ulcers complicated by massive hemorrhage].

The clinico-experimental investigation has shown high efficiency of the bilateral subdiaphragmatic truncal vagotomy in treatment of patients with acute gastroduodenal ulcers complicated by massive hemorrhage. The haemostatic effect of the operation is related to the inhibited acid gastric secretion, proteolytic activity of the intragastric content as well as to the activation of serotonin-containing cells and increased tonus of the sympathetic nervous system, which is responsible for gastric vessel spasm, shortens time of bleeding, increases the amount of thrombocytes and their aggregation. When vagotomy with interventions draining the stomach is not possible, suturing (dissection) of bleeding acute ulcers is recommended in combination with prolonged novocain blockade of vagus nerves.

Acute Disease↗
PubMed1988

[Circahoral rhythms of the skin biopotentials outside of digestion and their relationship to the periodic motility of the gastrointestinal tract].

Circahoral rhythms of the skin surface potentials recorded simultaneously with periodic motor activity of stomach in 4 dogs and 7 healthy subjects revealed the rhythms to be an electrophysiological equivalent of the latter in dogs. A "migration" of the group potentials in a certain spatial-temporal sequence was observed among the leads. It corresponded to the cycles of periodic motor activity of the stomach in dogs. The circahoral rhythms are a major topic for research in humans, too.

Adult↗
PubMed1986

[Rhythms of the digestive system and the body's biological clocks].

A hierarchic system of short-period rhythms are supposed to exist in the gastro-intestinal tract (GIT). A periodical activity (PA) of the GIT was considered from the standpoint of its role in the control of intraintestinal transit. A hypothesis is proposed concerning the structure and mechanism of the PA rhythm clock. The daily interaction of own rhythms of the enterometa-sympathetic system with the food intake triggers the intramuscular oscillator, two physiologically significant signals of which (filling up of the stomach and transit to the colon) are under the control of higher nervous centers. On the basis of the intramuscular oscillator, a central also double one, is formed, and a mutual neuro-humoral interaction is established between them. Significance of this mechanism is emphasized not only for the GIT activity but as a "timer" for ultraradian rhythms as well.

Activity Cycles↗
PubMed1986

[Characteristics of periodic motility of the upper portion of the jejunum in rabbits].

Proximal jejunal motility was studied balloonographically in rabbits devoid of food and in properly fed animals. Three phases of jejunal motor activity were revealed: the resting phase, irregular contraction phase and rhythmic phase. It was found that the regularity of rhythmic phase onset was not stable. The rate of continuous contractions during rhythmic phase and the rate of interrupted contractions during irregular phase coincided and were relatively constant. The feeding did not affect the rate of contractions during rhythmic and irregular phases, but increased the duration of the rhythmic phase.

Animals↗
PubMed1984

[Electrical activity of the cerebral cortex in fasting dogs with preserved and disordered gastric innervation].

Chronic experiments on 6 hungry dogs were made to record the motor periodicity of the stomach from fistulas in the fundal area and the electrocorticograms (ECoG) from bipolar electrodes implanted into cranial bones. Five months before experiments 2 dogs of the six were subjected to selective distal vagotomy. Analysis of 700 ECoGs allowed the conclusion to be made that apart from stereotyped periodicity of the frequency spectrum of the ECoG according to the phases of gastric motor periodicity cycles, in each successive cycle there add up unique compositions of 5 main ECoG frequencies, which do not recur in other cycles (within the range from 2 to 30 Hz) consequent on the asymmetry in electric activity of the right and left hemisphere cortex and on the phenomenon of migrating wave activation. Denervation of the gastroduodenal zone organs leads to substantial restitution and destabilization of the frequency spectrum of the ECoG, disorders in the regulation of migrating wave activation. It is suggested that the features of the ECoG described are linked with the enterogastric mechanisms of hunger motivation.

Animals↗
PubMed1983

[Functional and structural changes in the small intestine during experimental hypercholesteremia].

Functional and structural changes that occurred in the small intestine and liver of rabbits with alimentary hypercholesterolemia have been studied. Maximal rise of peripheral blood cholesterol after a single exposure to cholesterol was coupled with an increased penetration of chylomicrons and low and very low density lipoproteins from the intestine to the circulation. The decrease of cholesterol excretion along the whole length of the small intestine was accompanied by activation of the release of high density lipoproteins into the blood outflowing from the intestine. The decay of chylomicrons in the liver was restricted during the first days of hypercholesterolemia. Cholesterol concentration in the bile was decreased. The microvessels of the small intestine demonstrated the dilatation of the postcapillary-venular component erythrocyte aggregates and capillarostases.

Animals↗
PubMed1982

[Action of morphine on periodic gastric motor activity in dogs after selective distal vagotomy].

Chronic experiments on 9 dogs with gastric fistulas (with preliminary selective vagotomy in 5) were made to examine the action of morphine on periodic gastric motility (PGM). Morphine was injected subcutaneously at rest, selecting the minimal threshold vomitive dose (TVD) that provoked a series of contractions with a single vomiting attack, and the maximal dose that produced only an extra period of contractions. Clear-cut differences were discovered in the dogs' sensitivity to morphine (the groups with high and low sensitivity, the TVD 35 and 110 micrograms/kg on the average, respectively). Three consecutive stages were defined on the part of PGM in the response to morphine injection. After vagal denervation the sensitivity to morphine (as evaluated from the TVD magnitude) remained unchanged, the second stage (the alternating accelerated cycles) was lost, while the third stage involved continuous contractions. It is inferred that the primary reaction to morphine occurs as a result of eliminating the central inhibitory effects on PGM, the second stage is effected according to the mechanism of the enterogastric reflex, whereas the third stage reflects complete loss of the central and peripheral inhibitory mechanisms that regulate PGM.

Animals↗
PubMed1981

[Correlation between electroencephalogram rhythms and periodic gastric motility in fasting dogs].

The correlation between the frequency EEG spectrum and cycle phases of the gastric periodic motility was studied in the day and evening time in chronic experiments on 2 fasting dogs with chronic stomach fistulas and 8 pairs of silver bipolar electrodes implanted into the cranial bones. Consistent changes were observed in the correlation of rapid and slow EEG components according to each type of the periodic motility, the wave portion with a frequency of 2--8 Hz in the total electrical brain activity being minimum and that with a frequency of 20--30 Hz being maximum in the contraction phases. In the phases of the stomach rest, the correlations were reverse. The total portion of the waves with frequencies of 8--12 and 12--20 Hz changed insignificantly during each cycle. The time course of changes in the frequency EEG spectrum was also studied within each cycle phase. Preliminary verification of a possible role of the interoceptive signals from the contracted stomach in the mechanism of the correlation observed provided negative results.

Animals↗
PubMed1981

[Effect of pentagastrin on the periodic activity of gastroduodenal organs in dogs with intact and disrupted innervation of the stomach].

Chronic experiments on dogs with gastric and duodenal fistulas were made to study the effect of pentagastrin (6 micrograms/kg, s. c.) on the motor and secretory components of periodical activity of the gastroduodenal organs. Gastric secretion was collected from the open fistulas. To detect the role of the nervous mechanisms, subject to comparison were similar parameters of the periodic activity in 5 dogs with intact stomach innervation and in 6 dogs with preliminary circular gastrotomy in the upper third of the fundal part. Gastrotomy did not impair the periodical rhythm but led to the prolongation of the activity periods, decreased the contraction amplitude and shortened the periods of rest. The quantity of the periodical duodenal secretion was also diminished. In dogs with intact stomach innervation, pentagastrin inhibited the periodic contractions, stimulated the duodenum motility and caused an intensive special period of duodenal secretion. In disturbed innervation, these effects were less pronounced or completely disappeared. It is concluded that central parasympathetic innervation plays an important role in he mechanism of the pentagastrin effect on the periodic activity of the gastroduodenal organs.

Animals↗
PubMed1978

[Effect of ligation of the pancreatic ducts on endogenous serotonin distribution in the organs of the gastrointestinal tract].

The content of endogenous serotonin in the mucosa of various parts of the stomach and the small intestine and also in the homogenates of the pancreatic tissue and the peripheral blood was traced in the course of 12 months after the ligation of the pancreatic ducts in dogs. Marked and prolonged disturbances were revealed in the deposition of the endogenous serotonin characterized by definite regularities in all the tissues under study, connected with the changes of the relative constancy of the enteral medium due to the absence of pancreatic secretion in the lumen of the digestive tube.

Animals↗
PubMed1978

[Role of intestinal hormones in the pathogenesis of experimental pancreatitis].

In acute experiments on dogs with preliminarily induced pancreatitis the authors traced disturbances of the secretory reactions of the pancreas in response to adequate stimulation with the intestinal hormones. There was a reduction in the activity of complex intestinal hormones preparations obtained from the duodenal mucosa at the acute period of the disease in these dogs. In chronic experiments there was found an increase of acid production debit in the stomach and a shift in the duodenal contents reaction in the acid direction in pancreatitis. A conclusion was drawn on an important pathogenetic role played by the intestinal hormones in the mechanism of disturbances of the pancreatic exocrine secretion in pancreatitis.

Amylases↗