Search

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)

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.

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.

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.

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)

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.

In 15 mongrel dogs, a mixture of exocrine and endocrine pancreatic tissue obtained by a simple procedure was implanted into the liver of the same animal through a branch of the portal vein. Five animals with partial pancreatectomy were used for a morphological study. In a second group of ten dogs, 5 delayed and 5 immediate pancreatectomies were performed. No diabetes appeared after the pancreatectomy. The subsequent blood glucose and insulin levels remained within or close to the normal range for several weeks in 9 animals and up to 10 months in a last one, still alive. In 9 out of 10 animals, the long term study was limited between 6 and 17 weeks by the development of a malnutrition syndrome with hepatic steatosis due to the lack of exocrine secretory function because of the pancreatectomy. The last animal still alive developed the malnutrition syndrome after a second complementary resection of a small pancreatic fragment left along the duodenum. This last animal without diabetes at the 45th week suggests that the endocrine function of the autotransplanted pancreatic tissue could be maintained over a long period of time.

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.

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. Seven days after creation of an obstruction with bile derivation, 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. These results suggest that the secretion in the obstructed intestine is not influeced by the presence of bile.

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.

Two groups of mongrel dogs underwent intrasplenic autotransplantation of pancreatic tissues prepared from the head and tail of the organ. In the first group (12), the operation was terminated by the removal of the rest of the gland. In the second group (8), total pancreatectomy was done 6-8 months after autotransplantation. The first group of dogs became spontaneously normoglycemic after ten days of moderate hyperglycemia; their insulinemia increased significantly during a glucose loading test. The second group of dogs never became normoglycemic but remained vivacious; insulin level in their splenic vein increased moderately only after glucose injection. Microscopically, exo- and endocrine pancreatic tissues were seen in the spleens of the first group of dogs; in the spleens of the second group of dogs, only a few degenerating B cells were observed. These results suggest that the temporary hyperglycemia following autotransplantation of pancreatic tissues is a functional demand: it is necessary for ultimate survival and function of transplanted B cells.