[Preservation of hepatocytes of the rat by active transport of glycine]. / Etude de la conservation des hépatocytes de rat par la méthode de transport actif de la glycine.

The measurement of the active accumulation of specific substrates against a concentration gradient in tissue fragments in vitro has proved to be a simple but excellent procedure to ascertain the viability of several cell types and, in parallel with routine microscopy, has become a reliable tool in assaying the biochemical and functional modifications of a tissue under physiopathological conditions. It also has the added advantage of using tissues that are not pretreated in any way such as the preparative procedures used in cell isolation methods. The majority of investigations employing hepatocytes has been carried out in material derived from cell cultures or on isolated cells in suspension. The aim of this study was to determine if active transport could be determined in whole-tissue fragments of livers. Following identification of the specific substrate system and ideal incubation conditions, this method was then used to test the validity of different organ preservation solutions after cold storage in vitro. Livers were rapidly removed from rats and incubated for 1 hour at 37 degrees C in oxygenated Krebs bicarbonate buffer containing the substrates in question marked with a tracer dose of 14C. Preliminary investigations showed that active transport by rat hepatocytes was non-existent for beta-methyl-glucoside, phenylalanine and AIB; low for arginine but very important for glycine and serine and that this uptake could be significantly abolished by the presence of choline in the incubation medium.(ABSTRACT TRUNCATED AT 250 WORDS)

[Value of antral mucosectomy, selective proximal vagotomy and a combination of the 2 procedures in serum gastrin production and inhibition of stomach acid. An experimental study]. / Valeur de la mucosectomie antrale, de la vagotomie sélective proximale et de la combinaison des deux procédés dans la production de gastrine sérique et l'inhibition de la production acide de l'estomac. Etude expérimentale.

This experimental study was aimed at determining the volume and acidity produced by the normal stomach, following antral mucosectomy (MA), proximal selective vagotomy (VSP) and combination of both procedures. In 10 mongrel dogs, a double-lumen tube was placed in the stomach under general anesthesia. One of the lumen was rinsed with a constant flow and the other retrieved the gastric secretion. Gastric secretion and acidity were calculated every 10 minutes for 120 minutes. At 60 minutes, pentagastrin was injected. After these controls, a MA was carried out in half the animals and a VSP in the other half. 6 and 12 weeks postoperatively, the same controls were repeated. The dogs were then submitted to the operation of the other group. Following MA and pentagastrin stimulation, the gastric secretion (volume) is not modified with regard to the preoperative levels. On the other hand, after VSP, pentagastrin stimulation induces only a small volume response. The vagus thus seems to be involved in liquid secretion of the stomach. Following MA, pentagastrin stimulation lowers gastric pH at 6 weeks but not at 12 weeks postoperatively. Gastrin is known to have a trophic effect on the oxyntic mucosa. This effect disappears in a few weeks and explains these different figures. Following VSP, gastric acidity decreases and plasmatic gastrin increases. In this situation, pentagastrin directly acts on a trophic mucosa and produces the important lowering of the gastric pH. Finally, after MA, pentagastrin induces an increase in plasmatic gastrin. This effect seems to be mediated by central stimulation of the nuclei of the vagus nerve.

Alanine uptake by the endothelium of canine blood vessels and by the vessels of human umbilical cord.

In order to determine whether the endothelium of vascular wall fragments possesses an active uptake mechanism for alanine identical to the one present in endothelial cells in tissue culture samples of canine aorta, carotid artery and vena cava, human umbilical cord vessels, were incubated in vitro in the presence of labelled alanine. In a series of experiments, it was observed that all the tissues investigated accumulated a significant amount of this substrate against a concentration gradient, and that the accumulation was saturable in the presence of sodium. This uptake was sodium-dependent, was significantly inhibited by ouabain and was greatly reduced under anoxic conditions. Finally, the uptake was completely abolished by prior mechanical or osmotic destruction of the intima. In conclusion, the very reproducible measurement of active alanine uptake in fragments of blood vessels may be a valuable method of evaluating the integrity of the endothelium.

[Development of a gastroplasty with variable diameter. Experimental study using artificial sphincters]. / Développement d'une gastroplastie avec stoma de vidange variable. Etude expérimentale faisant appel aux sphincters artificiels.

The vertical banded gastroplasty is currently the most popular technique in the surgical treatment of morbid obesity. This experimental study was aimed to create a gastroplasty with a variable stoma. The Marlex band was replaced by the cuff of an artificial sphincter to allow selective variation of the diameter of the stoma. The study was carried out on four mongrel dogs. The artificial sphincter was connected to a subcutaneous port. Injection of sterile fluid into the port inflates the cuff and decreases the surface of the stoma. The study was followed up for one year. Under gastroscopic control the system was regularly activated, the diameter and the surface of the stoma was measured and calculated. The sphincter allowed the surface of the stoma to decrease from 103 +/- 2.0 mm2 to 61 +/- 2.1 mm2. There was no significant variation of the surface for each volume unit injected into the system. After one year, the systems and stomachs were harvested and examined. It is possible to create a gastroplasty with a variable stoma. This system works without any technical problem. Microscopic examination of the stoma shows no peri-sphincteric fibrosis.

[An evaluation method for organ preservation]. / Méthode d'évaluation de solutions pour la préservation d'organes.

The determination of the active transport of alanine by canine endothelial cells was employed as a parameter to test cellular viability following conservation in vitro at 4 degrees C in Krebs bicarbonate buffer (KB), St. Thomas (ST), Euro-Collins (EC) or University of Wisconsin (UW) solutions. Following 24-hour conservation, active transport values demonstrated that the highest results were obtained with UW solution. At the same time, dog renal cortex slices were also tested under identical conditions and, once again, UW solution proved to be the best. Conservation was then extended to 72 hours and UW solution still afforded maximum protection of cellular viability.

[Origin of secretions after denervation of the small intestine in the dog]. / L'origine de la sécrétion après la dénervation de l'intestin grêle de chien.

The origin of the severe diarrhea appearing after intestinal denervation or transplantation was studied on the 3rd and 14th postoperative days in 5 groups of dogs undergoing total or partial denervation. The net movements of water and electrolytes were investigated by employing an experimental model of intestinal perfusion in isolated loops in vivo. The active uptake of phenylalanine and beta-methylglucoside and Na(+)-K(+)-ATPase activity were used for in-vitro evaluation. Bacteriologic and histological specimens were also taken. Following total denervation with anastomosis, a considerable loss of water and electrolytes as well as numerous E. coli were found in the entire small intestine. This net secretion is due to the stagnation of bacteria in the presence of complete denervation and the absence of food since the animals in this group could not eat properly following general anesthesia and surgery. Consequently, peristalsis was not stimulated and bacterial overgrowth occurred. In the group denervation with pseudo-anastomosis, perfusion studies showed a decrease of absorption in the jejunum and minimal but significant secretion in the ileum. A high number of E. coli was also present. Since the mucosa remained intact, nutrition per os was resumed in the immediate postoperative period and excessive water and electrolyte loss was avoided. The high number of bacteria was due to a decrease in intestinal motility since complete denervation was performed. In the denervation group, water and electrolyte movements were identical to those observed in the preceding group but the entire intestine remained sterile.(ABSTRACT TRUNCATED AT 250 WORDS)

Active uptake of amino acids by the urinary bladder epithelium of rat, rabbit, and dog.

Through a series of experiments employing tissue fragments incubated in vitro together with labeled substrates, it was observed that the tight urinary bladder epithelia of rat, rabbit, and dog possess the capacity of an active accumulation of amino acids against a concentration gradient. This uptake is saturable in the presence of sodium, is sodium-dependent, and is inhibited by ouabain. In comparison with other tissues, this phenomenon of active uptake is strikingly resistant to anoxia. The direction of uptake is from blood to lumen across the basolateral epithelial membrane. The induction of hyperplasia in the bladder epithelium of dogs very significantly increased the uptake of amino acids. Further studies should confirm the presence of this phenomenon in the human bladder.

Recombinant human interleukin-1 beta decreases serum carboxypeptidase N and modifies serum amino acid concentrations in rats.

The effects of recombinant human interleukin-1 beta (rhIL-1 beta) on various serum constituents were studied following subcutaneous injection (12.5 or 125 micrograms/kg) in female Wistar rats. Protein electrophoresis and the determination of the serum concentrations of carboxypeptidase N (CPN), aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, aldolase, total proteins, iron, urea, creatinine, and several amino acids were performed 12, 24, and 72 hr after injection. With both doses of rhIL-1 beta, iron, albumin, CPN, and lysine were significantly decreased whereas alpha 2-globulin, urea, and creatinine were significantly increased 12 hr after administration. Iron and CPN were still low after 24 hr but returned to normal levels after 72 hr. With the higher dose of rhIL-1 beta, only alanine and phenylalanine levels were increased after 12 and 72 hr, taurine after 12 hr, and methionine after 24 hr. There were no biochemical or histological signs of hepatotoxicity. The findings indicate that rhIL-1 beta produces a reversible alteration of various biochemical plasma constituents without any apparent signs of cytotoxicity. Moreover, the decrease in CPN observed may influence the degradation of inflammatory peptides.

Prevention of coronary restenosis by stenting.

Balloon angioplasty fails to provide acceptable long-term results for a significant proportion of patients. An intravascular mechanical support, developed with the aim of preventing restenosis and acute closure of diseased arteries after transluminal angioplasty, was implanted in 44 patients (39 male and five female), aged from 35 to 70 years (mean 56 years) with documented restenosis of native coronary artery (41 stents) and bypass grafts (12 stents). In the group of bypass graft patients there was no local restenosis and no major complication. In patients in whom stents were placed in native coronary arteries, the complication rate was higher (two patients died after coronary bypass surgery). One patient died suddenly at home. Except for one patient, in whom a new lesion developed proximally with extension into the stent, no case of restenosis could be observed. Despite the still relatively high complication rate, we feel that stenting may present a rational approach to the unresolved problem of restenosis after coronary angioplasty.

Intravascular stents to prevent occlusion and restenosis after transluminal angioplasty.

Occlusion and restenosis are the most common reasons that transluminal balloon angioplasty may fail to provide long-term benefit. An intravascular mechanical support was therefore developed with the aim of preventing restenosis and sudden closure of diseased arteries after angioplasty. The endoprosthesis consists of a self-expandable stainless-steel mesh that can be implanted nonsurgically in the coronary or peripheral arteries. Experiments in animals showed complete intimal coverage within weeks and no late thrombosis during a follow-up period of up to one year. We performed 10 implantations in 6 patients for iliac or femoral arterial disease; 24 coronary-artery stents were implanted in 19 patients who presented with coronary-artery restenoses (n = 17) or abrupt closure (n = 4) after transluminal angioplasty or deterioration of coronary-bypass grafts (n = 3). We observed three complications in the group with coronary disease. One thrombotic occlusion of a stent resulted in asymptomatic closure, a second acute thrombosis was managed successfully with thrombolysis, and one patient died after bypass surgery for a suspected but unfound occlusion. Follow-up in the patients has continued for nine months without evidence of any further restenoses within the stented segments. Our preliminary experience suggests that this vascular endoprosthesis may offer a useful way to prevent occlusion and restenosis after transluminal angioplasty. Long-term follow-up will be required to validate the early success of this procedure.

Effect of dimethyl sulfoxide on the function and structure of the intact and ischemic canine ileum.

The action of dimethyl sulfoxide (DMSO) was investigated employing an experimental model of intestinal perfusion in vivo of isolated loops of dog ileum before, during, and following 1-h ischemia. DMSO was administered either into the intestinal lumen or by a continuous injection via a branch of the artery supplying the experimental loop. In the intact intestine, intraluminal DMSO significantly decreased the net movement of water, electrolytes, and glucose without affecting either the active transport of phenylalanine and beta-methylglucoside or morphology. This inhibition was irreversible since, following DMSO removal, there was only partial recovery of water absorption, while the other parameters remained significantly low. Inhibition by DMSO was delayed when the substance was injected intraarterially (i.a.). Regardless of its route of administration, DMSO did not reduce the extent of ischemic injury in comparison with non-treated "Controls": during ischemia, all functional parameters were practically non-existent. Following the re-establishment of circulation, a net loss of water and electrolytes ensued, and active transport did not improve. In both instances, the structural alterations were those associated with ischemia of the experimental model employed: short, broad, club-shaped villi which had completely lost their epithelium, but fairly intact crypts. It can be concluded from the data presented that in the dog DMSO inhibits absorption in the intact ileum and exerts no protection against ischemic lesion.

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.

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.