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Biomedical subjects

V Mirkovitch

Publications and source records attributed to V Mirkovitch.

At least 37 records · Page 2Linked to original sources
PubMed1984

A long-term study of experimental duodenogastric reflux on the vagotomized stomach in dogs.

The possibility has been explored in dogs that the effects of chronic enteral reflux on the gastric mucosa may be modified by highly selective vagotomy (HSV). In both the innervated and the vagotomized stomachs, Roux-en-Y duodenogastrostomy induced mucosal hyperaemia and foveolar hyperplasia; the mucosa regained normal morphology after the elimination of reflux. Duodenogastrostomy without HSV did not influence basal serum gastrin but resulted in a significant increase in mucosal histamine. After duodenogastrostomy with HSV basal serum gastrin decreased significantly and mucosal histamine was not affected. It is concluded that foveolar hyperplasia is a reversible reaction of the mucosa to potentially damaging agents like enteral contents. It is also suggested that the combination of chronic enterogastric reflux, abnormal gastrointestinal motility and HSV might have an inhibitory effect on gastrin release.

Animals↗
PubMed1984

A long-term study of different types of experimental alkaline reflux and the effects of its suppression in dogs.

The gastric mucosa of 19 mongrel dogs was submitted to a bilio-pancreatic, isolated biliary or isolated pancreatic reflux. With an isolated biliary reflux, there is a more rapid and more severe hyperaemia and foveolar hyperplasia of the mucosa of the fundus than with an isolated pancreatic reflux. There was no significant change in the basal serum level of gastrin with any of these different types of alkaline reflux, but we observed a statistically significant increase in the level of histamine in the gastric mucosa. Hyperaemia and foveolar hyperplasia of the fundic mucosa both disappeared when the alkaline reflux was suppressed, and there was a statistically significant decrease in the basal serum level of gastrin and in the level of histamine in the gastric mucosa.

Animals↗
PubMed1982

Functional alterations in the dog colon mucosa following temporary ischaemia.

Segments of dog colon were subjected to 1 h of total ischaemia. In one experimental group, the colon was not touched before the trauma; in another, it was rinsed out before the intervention; while in a third, it was perfused with Krebs bicarbonate buffer during injury. In all groups, the mucosa after the trauma is the site of net movement of water, sodium and chloride towards the lumen, while glucose absorption is greatly reduced. The accumulation of amino acid and sugar in vitro by samples of ischaemic mucosa is reduced but not abolished. The capacity for organic solute transport in vitro is greater in samples removed after the perfusion than in specimens excised immediately after the end of the ischaemia. According to the test in vitro, the mucosa can be protected from the deleterious effects of the ischaemia by intraluminal perfusion during the ischaemia. Immediately after 1 h of ischaemia, slight alterations in the histological structure of some villi were observed under the light microscope in occasional animals, particularly when the colon was not rinsed out before the ischaemia.

Animals↗
PubMed1980

The effect of cyclic AMP on dog renal function.

The infusion of dibutyryl-cyclic AMP into the dog renal artery in vivo leads to diuresis, natriuresis and glucosuria. Addition of the nucleotide to the incubation medium bathing dog renal cortex slices in vitro causes inhibition of p-amino-hippurate accumulation and stimulation of glycine and beta-methyl-glucoside transport. The results are interpreted in terms of the development of a blood-lumen flux of sodium and water in the renal proximal tubule, analogous to that seen in the intestine.

Animals↗
PubMed1980

Source of net water and electrolyte loss following intestinal ischaemia.

Ischaemia of the dog intestine lasting 1 h causes desquamation of the epithelium at the villus tips and congestion in the villus capillaries. The crypt cells are relatively undamaged. These changes are associated with a loss of active transport of organic solutes, determined in vitro, a reduction in mucosal sucrase activity and an abolition of glucose absorption in vivo. A profuse net loss of water and electrolytes into the lumen in vivo develops. The net sodium loss is due primarily to an inhibition of the lumen-blood flux of this ion, the blood-lumen flux being relatively unchanged. In uraemic dogs, the loss of urea into the lumen is the same in control and ischaemic loops, testifying to the lack of change in the unidirectional water flow from blood to lumen. Perfusion of the dog intestine with 1% Triton X-100 leads to morphological changes that have certain similarities with those provoked by ischaemia. Damage was restricted to the villus tips, protection from further alterations apparently being provided by a mucus layer that forms on the mucosal surface; the crypt region remained unchanged. After 10 min exposure, organic solute transport in vitro and glucose absorption in vivo were both reduced by not abolished; sodium and water absorption in vivo were suppressed, but no net secretion occurred. To account for these observations, we have suggested that the normal crypt cell is a secretory element with respect to sodium and water. During maturation, its absorptive properties develop such that the mature enterocyte, possessing both absorptive and secretory mechanisms, is capable of net absorption of sodium. After destruction of the villus tips, net secretion continues in the crypts; if there are insufficient villus cells remaining to ensure reabsorption, a net secretory capacity is observed.

Animals↗
PubMed1980

Morphological and functional recovery of the canine gallbladder mucosa following two hours' ischemia.

Temporary interruption of the circulation to the canine gallbladder causes hemorrhagic necrosis of the mucosa and an abolition of active transport of glycine in vitro. The first signs of epithelial recovery following two hours' ischemia are seen in animals examined 7 days after the injury and are characterized by the appearance of a layer of cuboidal epithelial cells in which some mitotic figures are observed, accompanied by a decrease in the amount of necrosis and the presence of granulation tissue. At the same time, there is some slight resumption in glycine uptake. Two weeks after injury, the new epithelium covers a larger surface of the gallbladder wall but recovery is still incomplete. Four weeks after operation, structural and functional recovery has occurred in almost all the animals studied: the epithelium is columnar and does not differ greatly from that seen in the normal gallbladder. Mucosal folds are present although their morphological appearance is slightly altered in comparison with those of control specimens. The gallbladder wall is thickened by fibrosis. Measurements of active glycine transport in vitro confirm that the new epithelium functions normally.

Animals↗
PubMed1980

[Functional changes after occlusion of the colon in the dog].

One or two weeks after total mechanical occlusion of the dog colon, the organ is severely dilated, but the intraluminal pressure never exceeds 8 cm of water, and there are no obvious histological lesions of the mucosa. Perfusion of the occluded colon in vivo reveals marked inhibition of ion and water absorption; however, except in the case of potassium, net secretion as occurs in the occluded ileum does not develop. Glucose absorption in vivo and active phenylalanine and beta-methyl-D-glucoside transport in vitro are reduced in the mucosa of the occluded colon.

Animals↗
PubMed1980

[Biotransformation of vascular prostheses].

Fifty arterial implants in animals and sixteen arterial implants in man have been examined with the scanner electronic microscope. After these examinations it appears to be that the form of biological reaction of the vessel graft is mostly determined by the condition of the host artery. If the host artery is healthy, even a synthetic prothesis will undergo a kind of revitalisation. However, if the host artery shows arteriosclerotic changes, even a healthy implant will be changed into a fibrotic tube.

Animals↗
PubMed1979

Minor hemobilia. Clinical significance and pathophysiological background.

Profuse hemorrhage into the biliary tract--major hemobilia,--is an alarming condition which attracts much attention. Minor hemobilia, often caused by gallstones or operative injury, is much more frequent, yet often neglected. Clinical observations indicate that minor hemobilia is not always an innocent condition with the blood remaining fluid and unobtrusively flowing into the intestine. Examples are given where clots from occult hemobilia have caused diagnostic errors or obstructed the bile flow, thus imitating gallstones for which they may be mistaken. Experiments have been performed to elucidate the pathophysiology of this clot formation: 1) A model of the biliary tract was constructed with bile flowing through it. When blood was injected forcefully to simulate a major hemorrhage, mixed clots of blood and bile were formed. When introduced gently, as in minor hemobilia, the blood flowed immiscibly to the lowest level where it formed a clot of pure blood. The clots dissolved under the influence of flowing bile, but remained intact when protected from the flow. 2) Mixed clots were mushy and dissolved spontaneously, while pure clots remained solid and stable. When clots containing increasing amounts of bile were incubated, increasing amounts of cleavage products of fibrinogen and fibrin were formed. 3) Blood clots were produced in gallbladders of 33 dogs. Pure clots remained solid and floating while mixed clots formed a mushy layer, strongly adherent to the mucosa. Both kinds of clots disappeared after two-four weeks, but remained if bile flow was diverted. These findings explain why under certain circumstances minor hemobilia acquires clinical significance by forming clots that may obstruct the flow or cause diagnostic errors. Successful dissolution of "retained stones" may occasionally have the simple explanation that blood clots, mistaken for calculi, have been fibrinolysed. Consequently, in biliary obstruction or when defects are found on cholangiography, the possibility of blood clots in the ducts should be considered even in the absence of overt gastrointestinal hemorrhage.

Adult↗
PubMed1979

[Scanning electron microscopy study of autologous fascia lata and bovine xenograft as arterial prosthesis. An experimental study].

The present communication deals with the decomposition of thrombi and the formation of an endothelium in two different vascular prothesis. Devitalized bovine arteries which were enzymatically reduced to a collagen reticulum, and tubes made of autologous fascia lata were implanted into the arterial bloodstream of dogs. The implants were left in place for a time ranging between 30 min and four months. They were examined by scanning electronmicroscope with the cortical point method. This enabled us to reach the following conclusions: unprepared autologous fascia lata implanted into the arterial bloodstream has much more thrombogenous qualities than solcograft. The decomposition of thrombi and the formation of an endothelium is much faster accomplished in fascia lata than in the devitalized bovine artery. It is not possible to distinguish solcograft and fascia lata by the formation of endothelium only.

Animals↗
PubMed1978

Lack of effect of bile in pathogenesis of secretion in mechanical small bowel obstruction.

In dogs, the principal lesion in the ileal mucosa above a mechanical obstruction is the induction of a secretory state in which there is a net loss of water and electrolytes into the intestinal lumen. The role of stagnated bile as a possible agent provoking this secretion was explored by ligating the common bile duct and diverting the bile by means of an anastomosis between the gall bladder and the ileum distal to the obstruction. 7 days after creation of an obstruction with bile diversion, the functional and morphological changes in the obstructed loop were almost identical to those occurring in animals with obstructions without bile diversion. The secretory response above the obstruction continued unabated, with levels of cAMP in the secreting mucosae lower than in control tissues. These results suggest: (a) that the secretion in the obstructed intestine is not influenced by the presence of bile, and (b) that this secretion may not be secondary to an increase in mucosal cAMP levels.

Animals↗