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Biomedical subjects

M Aprahamian

Publications and source records attributed to M Aprahamian.

At least 55 records · Page 3Linked to original sources
PubMed1989

Pancreatic lithiasis: a rare cause of gastrointestinal hemorrhage.

The rare instance of a gastrointestinal hemorrhage caused by a lithiasis of the duct of Wirsung is described. The world literature records only 13 other cases. Pancreatic calculi cause hemorrhage by either migrating through the pancreatic parenchyma to perforate the duodenum, ulcerating the vessels of the periductal parenchyma, or rupturing the pancreas. The usual sign of this complication of chronic calcifying pancreatitis, difficult to diagnose, is repeated gastrointestinal hemorrhages and sometimes pain, as in epigastric colitis. The immediate therapy is control of the hemorrhage. With transcatheter occlusive techniques, radical surgery can be postponed until it is more tolerable.

Adult↗
PubMed1988

Comparative effect of chronic bombesin, gastrin-releasing peptide and caerulein on the rat pancreas.

This study was designed to compare, on a molar basis, the effect of chronic bombesin, gastrin-releasing peptide (GRP) and caerulein on pancreatic growth in the rat. These 3 peptides were administered s.c. 3 times daily for 4 days at the following concentrations: 0.036, 0.36, 3.6 and 7.2 nmol/kg of body weight. Bombesin and GRP induced pancreatic growth in a dose-dependent manner from 3.6 nmol/kg. This growth was characterized by an increase in pancreatic weight, its protein and RNA contents but not in DNA content suggesting cellular hypertrophy. Caerulein exerted a biphasic effect on pancreatic growth, inducing cellular hypertrophy at low doses since 0.36 nmol/kg and atrophy with the highest dose (7.2 nmol/kg). Bombesin and caerulein (until 3.6 nmol/kg) increased the pancreatic content in chymotrypsin more than in amylase. The 7.2 nmol/kg caerulein treatment depressed all enzyme activities while the same dose of GRP increased pancreatic lipase content. It is concluded that (1) bombesin and GRP are equipotent trophic factors for the pancreas; (2) caerulein is the most potent factor and exerts a biphasic effect on pancreatic growth; (3) pancreatic growth and synthesis and/or secretion of enzymes are not regulated through the same mechanism.

Amylases↗
PubMed1988

New approach for oral administration of insulin with polyalkylcyanoacrylate nanocapsules as drug carrier.

Polyalkylcyanoacrylate nanocapsules (mean size 220 nm), composed of spheric polymeric structures, have been used as a drug carrier for insulin. The rate of encapsulation of insulin is 54.9%, and we studied the therapeutic efficiency of the nanocapsules in diabetic and normal rats. When administered subcutaneously, insulin-loaded nanocapsules prolonged the hypoglycemic effect of insulin; the duration of this effect increased with the doses. When administered orally by force-feeding to diabetic rats, insulin nanocapsules (12.5, 25, and 50 U/kg) decreased fasted glycemia 50-60% by day 2. This effect was maintained for 6 or 20 days with 12.5 or 50 U/kg, respectively. Only the dose of 100 U/kg decreased fed glycemia by 25% in diabetic rats. In normal rats, hyperglycemia induced by an oral glucose load was reduced by 50% with the same dose of oral insulin nanocapsules. We concluded that polyalkylcyanoacrylate nanocapsules preserve the therapeutic effect of insulin when administered orally and prolong this effect when administered subcutaneously and orally.

Administration, Oral↗
PubMed1987

A new reconstituted connective tissue matrix: preparation, biochemical, structural and mechanical studies.

A fibrinogen derivative generated by thrombin was reacted with elastin to yield a new addition product or adduct between the two proteins. Addition of fibronectin, and then of collagen, did not interfere with the basic elastin-fibrinogen reaction and conferred the qualities of an artificial connective tissue to the product. Biochemical, structural and biomechanical aspects of the new matrix were studied. Aprotinin, heparin, thiomersal, and thiourea did not inhibit the main reaction; indeed, some of these ingredients improved the matrix cohesion. Scanning electron microscopy showed the genesis of a true network whose meshes were more reticulated by the addition of thiourea. Biomechanical studies, i.e., strength and elasticity showed the thiourea matrix to be the strongest. These intrinsic properties suggest the product could have biological and clinical applications.

Biocompatible Materials↗
PubMed1987

Small bowel bypass prevents the trophic action of cholecystokinin on the rat pancreas.

The effect of a chronic administration of cholecystokinin (CCK) on the rat pancreas has been studied in rats subjected to a 90% jejunoileal bypass or an intestinal transection (controls). Jejunoileal bypass, when compared to transection, did not modify the size of the pancreas but decreased its enzyme content, especially for amylase, and reduced the number of zymogen granules. These structural and biochemical changes were maintained when bypassed animals were treated three times daily and for six days with cholecystokinin (20 Ivy Dog Units (IDU)/kg). In contrast, CCK treatment in transected animals induced growth of the pancreas due to cellular hypertrophy and hyperplasia; pancreatic enzyme content, especially for chymotrypsin, and the population of zymogen granules in acinar cells were also enhanced. It is concluded that jejunoileal bypass prevents the trophic action of chronic CCK on the pancreas.

Animals↗
PubMed1987

Adduct formation between soluble fibrin monomers and elastin.

Monomers of fibrin generated from fibrinogen by thrombin reacted with elastin to give a new addition product or adduct. The adduct formation results from a covalent bond between both proteins, formation of which is dependent on elastin, fibrinogen and Ca2+ concentrations; but, Factor XIIIa did not intervene. Addition of fibronectin, together with fibrinogen, as cold insoluble proteins from human plasma, and of soluble collagen from rat tail tendon did not inhibit the first reaction. This enabled us to elaborate a new artificial connective matrix.

Animals↗
PubMed1987

Influence of repeated administration of bombesin on rat pancreatic secretion.

To study the effects of chronic bombesin on pancreatic growth and secretion, rats were injected subcutaneously, 3 times daily for 4 days with either saline or bombesin (10 micrograms/kg). Bombesin significantly increased the pancreatic weight and content in protein and RNA but not in DNA. The ratios of the three former parameters to DNA increased, suggesting cellular hypertrophy. The pancreatic content in enzymes was also elevated, especially for chymotrypsin and to a lesser degree for amylase. However, the volume of pancreatic secretion and the output of enzymes in response to CCK under a continuous infusion of secretin remained unchanged. The in vitro secretory response to caerulein and bombesin was reduced for amylase and lipase. It is concluded that chronic bombesin exerts a trophic action on the rat pancreas but decreases the sensitivity of each cell to hormonal stimulation.

Animals↗
PubMed1987

Transmucosal passage of polyalkylcyanoacrylate nanocapsules as a new drug carrier in the small intestine.

The enteral absorption of particles has been investigated in the dog using a colloidal drug carrier, polyalkylcyanoacrylate nanocapsules loaded with an iodized oil (Lipiodol), as a tracer for X-ray microprobe analysis in a scanning electron microscope. Nanocapsules are spherical capsules, 100 to 200 nm in diameter, with a continuous polymeric wall surrounding a cavity which encapsulates the drug. Administered in the jejunal lumen, Lipiodol nanocapsules improved the absorption of the tracer as indicated by increased concentration of iodine in the plasma of mesenteric blood. In order to follow nanocapsules at the cellular level, all tissue compartments were preserved in a life-like state by cryofixation and freeze-drying of intestinal biopsies. Nanocapsules appeared in the intestinal lumen close to the mucus, then in intercellular spaces and defects of the mucosa and finally in the lamina propria and blood capillaries; in this latter compartment, the iodine content was four-fold higher than after intra-jejunal administration of Lipiodol emulsion. This complete phenomenon occurred only at the tip of the villi and happened within less than 60 min. We conclude that nanocapsules enhance the rate of absorption of Lipiodol and transport the drug from the intestinal lumen to the vascular compartment using a paracellular pathway. Thus they may be useful as drug carrier for oral administration of many chemicals.

Animals↗
PubMed1987

Effect of chronic bombesin on pancreatic size, composition and secretory function in the rat.

Bombesin administered subcutaneously to rats, three times daily for four days, induces pancreatic growth at a dose of 10 micrograms/kg. Growth was characterised by an increased pancreatic weight and content in protein and RNA, accompanied by cellular hypertrophy. Chronic bombesin also enhanced the pancreatic content in chymotrypsin and to a lesser degree its contents in amylase and lipase. The volume of the secretion and the output of enzymes in response to CCK under an infusion of secretin, however, remained unchanged although the functional capacity of individual cells to secret amylase and lipase was reduced. It is concluded that chronic bombesin exerts a trophic action on the rat pancreas but decreases the sensitivity of each cell to hormonal stimulation.

Animals↗
PubMed1987

A slow wave frequency complex of the canine small intestine during the fasting state.

The electrical activity of the duodenum and proximal jejunum was studied in conscious healthy dogs implanted with unipolar silver electrodes. A computerized method was used for the calculation of the mean frequency of the slow wave for each consecutive minute of the electromyographic signal. A "slow wave frequency complex" was identified in the fasted animals. It was characterized by an increase of the mean frequency of the slow wave which ranged, from one dog to another, between 1 and 3 cycles/min. The complex lasted about 30 min. It consisted of two distinct phases: a phase of increasing frequency of the slow wave which lasted about one-third of the total duration of the complex and a phase of progressive return of the frequency to its precomplex value. Each phase III of the migrating myoelectric complex occurring in both the duodenum and the jejunum was associated with one slow wave frequency complex. The phase III began a few minutes before the start of the slow wave frequency complex and ended a few minutes before the slow wave frequency reached its maximum. Ectopic phase IIIs which occurred in the jejunum but not in the duodenum were not associated with slow wave frequency complexes. The slow wave frequency complex was never seen in the fed dogs.

Animals↗
PubMed1986

[Vascular malformations of the colon. A frequently undetected etiology of lower digestive hemorrhage].

Angiectasia of the right colon is a new entity which must be considered in cases of lower intestinal haemorrhage. Moore's classification is the one that is generally accepted today; it distinguishes between 3 types the most interesting and best individualized of which is type I. It consists of acquired lesions occurring after the age of 60, often multiple, localized in the right colon and frequently associated with aortic stenosis and atheroma. The diagnosis of these vascular malformations is usually delayed because the lesions are submucosal and not visible at endoscopy. Bimesaraic arteriography may show typical images where extravasation of contrast medium is associated with vascular tuft or "tuff". Even the anatomicopathological confirmation of the diagnosis is difficult, since the lesion can only be located by special techniques, such as intra-arterial injection of a silicone-containing substance. Owing to the failure of modern techniques such as embolization, the only possible treatment is surgical, based on resection of the colonic segment involved.

Arteriovenous Malformations↗
PubMed1986

[Mechanical sutures in digestive surgery. A critical study].

An objective review of the experimental and clinical literature comparing stapled- and hand-sutured anastomoses in gastrointestinal surgery is presented. Experimental studies support the hypothesis that stapled-sutured lines heal by primary intention, thus avoiding the inflammatory time lag, and resulting in a stronger wound during the first post-operative week. In contrast, manual sutures always produce an early inflammatory reaction with a transitory rise in collagenase activity in the submucosa, which explains the particular fragility of the anastomosis during that phase. Nevertheless, it was difficult to find a concordance between this histological quality of the stapled suture line and clinical results. In oesophageal surgery, a slightly higher rate of stenosis and a lower rate of anastomotic leakage were observed. In gastric and colorectal surgery, the superiority of the stapled suture was not proved. However, in colorectal randomized studies, the presence of "withdrawn" group for which the stapler was the only technically possible alternative, provides undeniable proof that this technique is an indispensable adjunct in modern digestive surgery. Conversely, its value seems negligible in surgery of the small bowel or of the intraperitoneal colon where manual suturing remains the technique of choice.

Acute-Phase Reaction↗
PubMed1986

Longitudinal distribution of brush border hydrolases and morphological maturation in the intestine of the preterm infant.

The morphological maturation and the distribution of brush border hydrolase activities were studied in the small intestine and the colon in newborn babies of 28-38 weeks gestational age. Lactase and sucrase activities were higher at term with maximal activity in the proximal intestine. In contrast, aminopeptidase and glucoamylase exhibited maximum activity in the distal part of the small bowel. Glucoamylase activity was already significant in the small intestine and in the colon of the preterm newborn. Sucrase activity present in the proximal colon of the preterm dropped to a negligible amount at term, whereas aminopeptidase activity increased, reaching values found in the small intestine. The enzymic changes occurring in the intestinal tract were related to the morphological maturation of the mucosa from fetal to adult type during late gestation. Accelerated morphological and functional maturation was observed in one preterm infant nourished intravenously for 12 days, these processes being independent of the presence of nutrients in the intestine. At term, the distal part of the intestine seems to have increased digestive capacities for peptides and polysaccharides. We present evidence that full-term, and to a lesser extent preterm infants are able to hydrolyse glucose polymers.

Aminopeptidases↗
PubMed1986

Small-intestinal and colonic changes after biliopancreatic bypass for morbid obesity.

Morphologic and functional adaptations of the functioning intestine were evaluated in 41 patients before and after biliopancreatic bypass for morbid obesity. This surgical procedure diverts pancreatobiliary secretions via the duodenum and the jejunum into the colon, the remaining small intestine being anastomosed to the stomach after antrectomy. In the proximal ileum there was an 80% increase of the height of villi; the specific activities of maltase, sucrase, and aminopeptidase in brush border membranes remained unaffected, and that of lactase tended to decrease. In the distal ileum villi heights increased only by 58%, and disaccharidase activities (except for maltase) were slightly enhanced. In the colon the mucosa displayed, in some patients, focal appearance of true villi, and brush border enzyme activities increased concomitantly. We conclude that biliopancreatic bypass induces an adaptation of all intestinal segments of the functioning intestine; this adaptation tends to compensate for the shortening of the gut continuity.

Adult↗
PubMed1986

[Autotransplantation of the spleen. A new possibility in the conservative surgery of the spleen].

Conservative surgery to spleen is an ancient concept brought up-to date by improved knowledge of its fundamental roles in immunity and anti-bacterial defences. Suture of spleen and partial splenectomy ensure the best possible functional results but have technical limitations resulting frequently in splenectomy to provide hemostasis. Data from clinical and experimental studies and reports in the literature have demonstrated that autotransplantation of spleen is a simple, safe and effective method for preventing the true dangers of asplenia. Optimal results from autotransplantation of spleen are obtained when the injured organ is broken into small fragments which are then implanted into small spaces fashioned in the greater omentum. Clinical and biological tests to evaluate functional value of these transplants have shown that results approach those of a normal or sutured spleen. It is concluded that this procedure, which completes other conservative methods of splenic surgery, should definitely exclude hemostasis splenectomy from therapy of injuries to spleen.

Animals↗
PubMed1985

[Pancreatic and intestinal adaptation following proximal or distal resection of the small intestine in the rat].

The comparative effect of a 50% proximal or distal enterectomy on the exocrine pancreas and the remaining intestine has been studied in the rat one month after operation. Distal enterectomy induces (1) growth of the pancreas, characterized by a parallel increase in pancreatic weight, protein, DNA, RNA, amylase, lipase and chymotrypsin content, (2) preferential adaptation of the remaining ileum. Proximal enterectomy did not modify the pancreatic parameters studied but brings about an adaptation of the duodenum, the remaining jejunum and the ileum. It is concluded that pancreatic and intestinal adaptations differ after proximal and distal enterectomy.

Adaptation, Physiological↗