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Biomedical subjects

M Aprahamian

Publications and source records attributed to M Aprahamian.

At least 73 records · Page 4Linked to original sources
PubMed1985

Combined effect of chronic bombesin and secretin or cholecystokinin on the rat pancreas.

This work investigates the pancreatico-trophic action of bombesin, a peptide stimulating pancreatic secretion in vivo and in vitro and examines whether this effect is altered by CCK or secretin. Rats were injected three times daily for 5 days either with saline, bombesin (1 or 10 micrograms/kg), CCK (20 I.D.U./kg), secretin (20 C.U./kg) or a combination of bombesin and CCK or secretin. Bombesin alone induced growth of the pancreas beginning with the dose of 10 micrograms/kg. This growth was characterized by an increase of pancreatic weight, its protein, RNA and enzyme content, but not of its DNA content. The ratios of the three former parameters to DNA increased, suggesting cellular hypertrophy. Cholecystokinin alone exhibited a similar trophic action on the pancreas as bombesin. Secretin alone had no effect on pancreatic size and composition. Cholecystokinin and secretin did not modify the pancreatico-trophic response of bombesin. These findings suggest that bombesin, administered for 5 days in the rat, induces pancreatic growth due to cellular hypertrophy. Cholecystokinin has the same effect. However the mode of action, at the cellular level, of bombesin appears to be different from that of cholecystokinin.

Animals↗
PubMed1985

Trophic effect of bombesin on the rat pancreas: is it mediated by the release of gastrin or cholecystokinin?

This work investigates the effect, on the rat pancreas, of a chronic administration of bombesin in function of the dose and duration of treatment and examines whether this effect may be mediated by the release of endogenous gastrin or cholecystokinin. Bombesin, administered three times daily for 5 or 15 days, induced a marked increase in pancreatic weight, its protein, RNA and enzyme contents with the dose of 10 micrograms/kg body weight; the ratios of pancreatic weight, protein and RNA contents to DNA contents increased significantly after a 5 day treatment, suggesting cellular hypertrophy. Pancreatic DNA content was markedly enhanced after a 15 day treatment, suggesting cellular hyperplasia. Antrectomy decreased plasma gastrin levels, but did not alter the pancreatico-trophic action of a 10 micrograms/kg bombesin treatment for 5 days. Proglumide, an inhibitor of cholecystokinin and gastrin in the pancreas, did not affect the growth of the pancreas induced by a 10 micrograms/kg bombesin treatment for 5 days. It is concluded that chronic bombesin induces, in the rat pancreas, cellular hypertrophy or hyperplasia depending on the duration of treatment. Pancreatic hypertrophy is not mediated by the release of endogenous gastrin or cholecystokinin.

Amylases↗
PubMed1985

Effects of supplemental pantothenic acid on wound healing: experimental study in rabbit.

The effect of pantothenic acid supplementation and deficiency on wound healing was investigated over a one month postoperative period in rabbits. The supplemented group was injected with pentothenate (20 mg/kg of body weight/24 h) for three weeks and compared to a placebo group (0.5 ml of distilled water). Deficient animals were fed with a pantothenate free diet also for three weeks. These three experimental groups were matched against a control group. The degree of wound healing was determined by the mean of postoperative breaking strength and wound fibroblast population changes. Pantothenic acid urinary excretion measured by gas chromatography served as control of pantothenate consumption. With regard to these three parameters no significant difference has been found between placebo and controls. The average urinary elimination in the pantothenic acid group was significantly higher as far as the pantothenate supplemented group was concerned, while the deficient group showed no significant decrease when compared to controls. Chronic pre- and postoperative pantothenic acid supplementation significantly increased aponeurosis strength after surgery; it improved slightly, but not significantly the strength of the skin. Furthermore, the fibroblast content of the scar became significantly greater during the fibroblast proliferation phase after pantothenic supplementation. These data suggest that pantothenic acid induces an accelerating effect of the normal healing process. The mechanism responsible for this improvement seems to be an increase in cellular multiplication during the first postoperative period. But the exact intimate mechanism of the beneficial effect of pantothenate remains unclear.

Animals↗
PubMed1985

Gastrin modulation of pancreatic growth.

Gastrin has been proposed as a trophic factor for the pancreas. Extensive small-bowel resection increased transiently plasma gastrin levels in the rat and produced pancreatic growth. This growth was characterized by an increased pancreatic weight, protein and DNA content, and the occurrence of mitotic figures in acinar cells. In order to determine if gastrin is implicated in pancreatic hyperplasia, we induced endogenous variations of gastrin 3 weeks before small-bowel resection or transection. Hypogastrinemia was produced by antrectomy and hypergastrinemia by vagotomy plus pyloroplasty. Pyloroplasty alone was without any effect. All gastric operations alone enhanced though not significantly the weight of the pancreas and its content in protein and DNA. When performed before intestinal resection, they did not modify the hyperplastic response of the pancreas to the resection. Our findings do not support the views that antral gastrin exerts a trophic action on the rat pancreas and that gastrin is implicated in postresectional hyperplasia of the gland.

Animals↗
PubMed1984

Effects of wheat bran on the exocrine pancreas and the small intestinal mucosa in the dog.

Five Beagle dogs, equipped with duodenal and gastric fistulae, were fed a standard diet before receiving the same diet supplemented with wheat bran for 1 month. Pancreatic secretory investigations performed in conscious animals before and 1 month after bran administration showed a significant parallel increase in the flow rate of pancreatic secretion and the outputs of bicarbonate and amylase both in basal and secretin-stimulated conditions. The outputs of protein and chymotrypsin increased only in unstimulated secretions, while the output of lipase was strongly reduced in response to secretin. However, the small intestinal mucosa was not affected by bran administration. Dietary fiber did not alter the height of the villi or the activity of sucrase, maltase and aminopeptidase in mucosal homogenates or isolated brush border membranes from intestinal biopsies. These data suggest that wheat bran supplemented to the standard diet affects the exocrine pancreatic secretion but not intestinal enzyme activities involved in the absorption of carbohydrates and proteins in the dog.

Amylases↗
PubMed1984

Protein malnutrition after jejunoileal bypass in the rat. Possible contribution of the exocrine pancreas and the included intestine.

A 90% jejunoileal bypass induces in the rat a protein malnutrition state which is characterized (1) by the decreased level of plasma proteins and albumins and (2) by the reduced level of most essential and non-essential plasma amino acids. In the exocrine pancreas there was a decreased content of digestive enzymes, especially of amylase, while the secretion of enzymes studied in vitro was reduced. In the ileum left in one piece, the specific activities of maltase and sucrase increased significantly while aminopeptidase was unaffected. It is suggested that exocrine pancreatic insufficiency observed after small bowel bypass in the rat might contribute to protein malnutrition (1) by producing maldigestion and (2) by inducing an imbalance in intestinal enzymes favouring a preferential absorption of carbohydrates compared to proteins, thus emphasizing the protein malnutrition state.

Animals↗
PubMed1984

Pancreatic hyperplasia after small bowel resection in the rat: dissociation from endogenous gastrin levels.

Extensive small bowel resection produces pancreatic hyperplasia and increases plasma gastrin levels in the rat. Because gastrin is known as a trophic factor for the exocrine pancreas, we studied the effect of endogenous variations of gastrin induced by different gastric operations on the rat pancreas in both resected and transected animals. Vagotomy increased plasma gastrin level while antrectomy decreased it; pyloroplasty was without any effect. These gastric operations enhanced slightly but not significantly the pancreatic weight, its protein and DNA content. A 90% jejunoileal resection alone increased markedly these parameters while mitotic figures appeared in acinar cells. Pyloroplasty, vagotomy and antrectomy did not modify the changes induced by intestinal resection itself except the level of protein. These findings suggest that hypergastrinemia produced by intestinal resection is not responsible for pancreatic hyperplasia.

Animals↗
PubMed1984

[Gastrin is not implicated in intestinal adaptation after extensive resection of the small intestine in rats].

Because gastrin is thought to be a trophic agent for the digestive tract, we studied the effects of endogenous variations of plasma gastrin on the small intestinal mucosa after a 90 p. 100 jejunoileal resection in the rat. Hypogastrinemia was induced by antrectomy while hypergastrinemia resulted from vagotomy. Pyloroplasty had no effect on gastrinemia. Small bowel resection increased mucosal weight, DNA and protein content; these changes were more obvious in the jejunum and ileum than in the duodenum. Gastric operations performed before the resection did not significantly modify these parameters except for the level of protein. Our results indicate that endogenous gastrin plays no role in the adaptive growth response of the intestinal mucosa after extensive small bowel resection.

Adaptation, Physiological↗
PubMed1983

Effect of dietary fiber supplementation on the secretory function of the exocrine pancreas in the dog.

The effects on pancreatic secretion of a diet supplemented with wheat bran for one month were studied in five dogs provided with chronic pancreatic and gastric fistulae. Dogs were subjected before and after bran administration to a continuous intravenous infusion of secretin (GIH, 0.5 U/kg/h) alone and a combination of secretin with cerulein (25 or 100 ng/kg/h). Exocrine pancreatic secretions under basal conditions were collected during the intravenous infusions of normal saline. Wheat bran supplementation for 4 wk to the standard diet in dogs increased pancreatic juice flow rate along with bicarbonate and amylase output whether the secretion was unstimulated or stimulated with caerulein alone or combined with secretin. No significant changes in the concentration of pancreatic bicarbonate, amylase, chymotrypsin, and proteins were noted under stimulated conditions. Furthermore, lipase concentration and output were dramatically reduced. These data indicated that wheat bran supplemented to the standard diet in dogs affects the exocrine pancreatic secretion whether it was unstimulated or stimulated by secretin alone or combined with cerulein.

Animals↗
PubMed1983

Effect of chronic alcohol administration on the exocrine pancreas after jejunoileal bypass in the rat.

To determine whether intestinal bypass operation and alcohol administration exerted a synergistic effect on pancreatic enzyme composition and morphology, adult rats were submitted either to a sham-operation or to a 90 per cent jejunoileal bypass. Two weeks after the operation, the rats received a 15 per cent solution of ethanol in drinking fluid during a period of four weeks while controls received water. In sham-operated animals, alcohol had no effect on pancreatic weight or its total content in protein and amylase. The general structural and ultrastructural aspect remained unchanged except for the presence of a few mixed acinar-islet cells. Bypass operation alone induced a significant decrease in amylase content while the population of zymogen granules was reduced. Parallely, lipid droplets deposited within acinar cells. Alcohol administered in bypassed animals exerted a synergistic effect on fat accumulation in pancreatic acinar cells but had no effect on other biochemical and morphological parameters.

Amylases↗
PubMed1982

Copper accumulation in primary biliary cirrhosis. An electron and X-ray microanalytical study.

Ultrastructural and X-Ray microanalytical aspects of primary biliary cirrhosis were analysed and compared to those of normal liver. Electron microscopic studies showed a significant increase of dense lipofuscin-like granules in PBC compared to the hepatocytes of normal liver (665%). These granules (0.3-2.7 micrometers in diameter) were formed by the association of primary lysosomes and lipid droplets. X-Ray microanalysis of these structures showed the presence of Calcium, Phosphorus, Potassium, Chlorine, Sulphur, Aluminium and Copper. The coexistence of Sulphur with other mineral elements suggests the occurrence of metalloproteins binding these elements. These findings provide evidence that intralysosomal sequestration of mineral elements, especially copper protects the hepatocytes from cytotoxic effects.

Copper↗
PubMed1981

Ultrastructural changes in the rat exocrine pancreas after jejunoileal bypass.

The influence of a 90% jejunoileal bypass on the rat exocrine pancreas was studied by morphometrical procedures. In sham-operated animals exocrine acinar cells accounted for 80.3% of the pancreas volume. These cells are composed of 9.9% nuclei, 8.4% mitochondria, 12.2% zymogen granules, 0.3% lipid droplets and 69.2% of a compartment ("ERGLS") composed of endoplasmic reticulum, ribosomes, Golgi areas, lysosomes and the cytoplasmic ground substance. Intestinal bypass did not change the volume density of exocrine cells nor that of nuclei in the cells during the three postoperative months. The means nuclear diameter was approximately the same in both groups. However, the volume density of secretory granules diminished by 50%. This was accompanied by a decrease in mean granular diameter, but not in their numerical density. The volume density of lipid droplets increased 10 fold, that of mitochondria increased slightly from the 15th postoperative day but significantly from the 45th day. The remaining cellular compartment composed of "ERGLS" was not modified by intestinal bypass. These findings suggest that a 90% jejunoileal bypass induces major changes in the composition of pancreatic acinar cells but not in their size.

Animals↗
PubMed1981

Inhibition of canine duodenal interdigestive myoelectric complex by nutrient perfusion of jejunal and ileal Thirty-Vella loops.

The mechanisms by which the intestinal interdigestive myoelectric complex (IDMEC), recurring at about 90 minute intervals in the fasted dog, is disrupted by feeding remain unknown. We investigated whether the IDMEC could be disrupted in the duodenum by perfusing a Thiry-Vella loop with glucose in the dog. An intestinal Thiry-Vella loop, measuring one half (80 to 160 cm) of the total length of the small bowel was constructed in four dogs from the jejunum, and in four other dogs from the ileum. Extracellular nichrome electrodes were sewn on the duodenum for recording the electrical activity of the intestine. After three weeks' recovery, electrical recordings were performed in the fasted dogs in order to observe whether the IDMEC persisted in the duodenum when the Thiry-Vella loops were perfused, at different days, for four hours with solutions made of either (1) NaCl 154 mM, (2) NaCl 308 mM, (3) glucose 300 mM, or (4) glucose 600 mM, at a rate of 8 ml/min. NaCl 308 mM and glucose 600 mM were also delivered at a rate of 4 ml/min. Glucose output from the Thiry-Vella loops was measured throughout the experiments over consecutive five minute intervals. Each experiment was performed three times in each dog. The results showed that perfusing the Thiry-Vella loops with NaCl 154 mM or NaCl 308 mM did not suppress the IDMEC in the duodenum whether the flow rate was 4 or 8 ml/min. On the contrary, perfusing the jejunal loops with glucose 300 mM disrupted the IDMEC in 54% of the experiments; perfusing glucose 600 mM disrupted the IDMEC in 83% of the experiments. In the ileal Thiry-Vella loop experiments, the IDMEC was disrupted in 33% of the cases with glucose 300 mM and in 66% of the cases with 600 mM. No significant difference was observed with glucose 300 mM delivered at a rate of 8 ml/min and glucose 600 mM delivered at a rate of 4 ml/min. Finally, the inhibitory effect of perfusing the Thiry-Vella loops with glucose increased as the amount of absorbed glucose increased. These results indicate that interruption of the IDMEC by feeding probably involves extraintestinal factors. These factors do not seem to be specific for any one part of the small intestine, but they seem to be activated by intestinal absorption.

Action Potentials↗
PubMed1978

[Contribution to the study of gallstones. Morphological, radiological and cristallographic analysis (author's transl)].

The structure of gallstones has become of recent interest with the medical treatment of cholesterol stones. It seemed to us interesting to determine by morphological, radiological and above all cristallographic criteria the constituants of gallstones in order to draw up a practical classification which reflects better the biological reality. The present study confirms the existence of cholesterol and calcium carbonate in various types of stone, but reveals in addition the presence of cholesterol and bile salts associated with new mineral constituants identified for the first time (aluminium chlorite and silicate). The notion of pure stones, generally attributed to cholesterol and pigmented stones was only verified in the case of mineral stones.

Aluminum Silicates↗