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Biomedical subjects

J Ahonen

Publications and source records attributed to J Ahonen.

At least 217 records · Page 12Linked to original sources

Effect of defibrinogenation on collagen synthesis in granulation tissue. A study in the rabbit.

Collagen synthesis was studied in sponge-induced early granulation tissue from rabbits defibrinogenated by Arvin. Tissue slices were incubated in vitro with 14C-proline. The formation of 14C-hydroxyproline and the incorporation of 14C-proline into proteins was determined. The incorporation of proline into collagen and proteins was equally reduced after defibrinogenation. A possible explanation for this is a reduced number of active fibroblasts in granulation tissue formed during defibrinogenation.

Afibrinogenemia↗

Granulation tissue formation in zinc-treated rats.

Chronic zinc deficiency impairs would healing. It is not known if acute decrease of werum zinc ocdurring after trauma has the same negative effect. We have studied the effect of extra zinc supply in connection with trauma on granulation tissue formation in subcutaneously implanted polyvinyl sponges. Zinc given postoperatively had no effect on granulation tissue formation. Zinc administered also preoperatively resulted in higher amount of collagen by the fourth postoperative day but not later. This effect of zinc on the collagen content can be explained either by an increased collagen synthesis or by decreased collagen break down. The fact that zinc had no effect when given only postoperatively indicates that collagen synthesis is not affected. The demonstrated effect of zinc thus seems to be due to decreased collagen break down.

Animals↗

Collagen synthesis in granulation tissue formed in rats treated with female sex hormones.

In previous studies, we have shown that female sex hormones given in dosages corresponding to plasma levels in the last trimester of pregnancy retard collagen accumulation in early phases of experimental granulation tissue formation. Results of incorporation experiments using radioactive proline reported in this article indicate that this hormone treatment reduces general protein synthesis in granulation tissue and, even more markedly, the synthesis of collagen. Since collagen accumulation into granulomas is normal in the later phases of healing, it is suggested that hormone treatment not only decreases synthesis of collagen but also decreases breakdown of collagen. Hormone treatment did not affect the solubility of labeled collagen. No differences were observed in the synthesis of different collagen types. Under conditions when active collagen and protein synthesis occurs in the uterus and fetus, corresponding synthesis in other tissues is, thus, decreased. This may serve as an energy and protein saving function during pregnancy. The results may have applications for treatment of extensive scar formation.

Animals↗

Cytochemical study of granulation tissue in zinc treated rats.

The effect of zinc administration on cell composition of early granulation tissue has been studied in rats using histological and cytochemical methods. Granulation tissue was obtained by subcutaneous implantation of polyvinyl sponges. The experimental group was given zinc intramuscularly daily beginning preoperatively. Zinc administration does not change the early inflammatory cell infiltration but results in a more rapid disappearance of polymorphonuclear granulocytes from the granulation tissue. No effect can be seen on the mononuclear cell population. The observations are related to alterations in repair processes following zinc administration.

Acid Phosphatase↗

Cardiac output distribution after left colon anastomosis in the rat.

Resection and anastomosis of the left colon result in an aysmmetric breakdown of preexisting collagen in the colonic wall during the first days of healing. Suture technique influences this reaction. To study the regional blood flow in the colon after resection and anastomosis a tracer microsphere technique was used for determination of the cardiac output distribution in four groups of rats: unoperated and sham-operated controls and rats with left colon anastomosis sutured either by continuous or interrupted sutures. There were no differences in the organ distribution of caridac output between unoperated and sham-operated controls. Left colon resection and anastomosis led to an increased regional blood flow in the colon, which was most marked proximal to the anastomosis and furthermore more pronounced in animals with anastomosis made of continuous suture than in those made of interrupted sutures. Further, resection and anastomosis resulted in an increased cardiac output distribution to the visceral organs. The visceral increase was most pronounced in animals with continuous suture. This increase was predominantly observed in the kidneys and in the colon. The latter is interpreted as being due to an increased metabolic demand induced by resection and anastomosis.

Animals↗

Liver damage after liver hilus dearterialization in dogs.

Twenty-one harrier dogs underwent a standardized liver hilus dearterialization with (7) or without (14) cholecystectomy using six sham-operated dogs as controls. Seven dogs died, only one of which was in the dearterialization and cholecystectomy group. S-OCT and s-GDH were increased at 90 minutes after dearterialization. There was no statistical difference between the groups at 90 minutes. On the first day after dearterialization, the activity of s-OCT, s-GDH, s-ALAT rose significantly (p less than 0.005). The activity of s-ASAT was, however, increased to the same extent both in the dearterialized and the sham-operated animals. A normalization of the serum enzyme activities was usually seen after one week. S-ALP increased on the first day (p less than 0.005) and still higher values were noted on the seventh day after dearterialization. Cholecystectomy did not affect any of these results except mortality. Liver oxygen consumption, in vitro was unchanged throughout the experiment. The oxygen consumption of bile duct mucosal scrapings one week after dearterialization was similar to the corresponding values in the controls. The results indicate that the dearterialization leads to a definite but mild and reversible mitochondrial and cell membrane damage. The results indicate further the need of adequate controls when the effects of dearterialization on the liver are studied.

Alanine Transaminase↗

Healing of experimental colonic anastomoses. The effect of suture technic on collagen concentration in the colonic wall.

The present experimental study in rats has demonstrated a marked difference in the healing process of anastomoses in the left colon following two different suture technics: continuous and interrupted sutures. Rats having anastomoses constructed of continuous suture showed a high incidence of complications and a marked decrease of collagen concentration in the anastomosis and in the colonic wall proximal to the anastomosis during the first week of healing. In animals with anastomoses made of interrupted sutures there were fewer complications, the decrease in collagen concentration was confined to the anastomotic region, and the recovery of collagen concentration occurred earlier. The findings indicate that the interrupted suture technic is preferable for anastomosis in the left colon.

Animals↗

Changes in calcium and hydroxyproline content of cortical bone after compression and neutral plate fixation.

Calcium and hydroxyproline content of intact rabbit tibio-fibular bone was assay chemically 1 day to 36 weeks after compression and neutral plate fixation with a 4-hole stainless steel ASIF/DCP plate. During the first three postoperative weeks calcium content of the cortical bone decreased by an almost significant amount (P less than 0.05); thereafter, calcium values remained subnormal but did not differ significantly from initial postoperative values. Hydroxyproline content increased steadily throughout the experiment (P less than 0.001). The changes in chemical composition of the bone were of the same magnitude after compression and neutral plate fixation. The results suggest that the cancellous transformation of cortical bone, known to take place under rigid plates, reflects an active remodelling process of the bone in which the calcium and hydroxyproline content changes only slightly.

Animals↗

Structural changes in intact tubular bone after application of rigid plates with and without compression.

The influence of a rigid plate on the structure of intact tubular bone was studied in forty adult rabbits using a four-hole commercial-steel DCP-ASIF plate attached to each tibiofibular bone, with and without compression. The morphological changes in the bone underlying the plate were examined and were assessed quantitatively at one day to thirty-six weeks after operation. The rigid plate induced porotic changes in the cortical bone, which were evident three weeks after the operation and increased rapidly between twelve and eighteen weeks. At thirty-six weeks, resorption cavities occupied 40.6 per cent of the cortical wall of the bones plated with compression and 41.2 per cent of the wall of those plated without compression. The changes were visible slightly earlier in the presence of compression. A rigid plate brought about a statistically significant increase both in the outer diameter of the bone and in the diameter of the medullary space as a result of subperiosteal new-bone formation and concomitant subendosteal bone resorption.

Animals↗

Revascularization in mesenteric infarction by reimplantation of the superior mesenteric artery. Report of a case.

A case of revascularization in mesenteric infarction by reimplantation of the superior mesenteric artery combined with intestinal resection is presented. The patient had an acute occlusion of the superior mesenteric artery with coincident blockage of celiac axis and inferior mesenteric artery resulting in gangrene and perforation of the small bowel. The good postoperative recovery suggests the usefulness of this method in selected cases.

Aged↗

Effect of rigid plate fixation on structure and mineral content of cortical bone.

The effect of rigid plate fixation on the structure and mineral content of cortical bone were studied by light and fluorescence microscopy and by chemical analysis of calcium and hydroxyproline content in 27 rabbits from one day to 17 weeks after the attachment of a 5 hole ASIF-plate onto intact femur. Between the second and seventeenth postoperative weeks the plated cortical bone became progressively thinner and porotically transformed. Subendosteal resorption was partly offset by the formation of new subperiosteal bone that resulted in a slightly wider than normal, thin-walled tubular bone. At 17 weeks the mean calcium content of the tubular bone under the plate was 15% less than the initial postoperative content (p less than 0.05). The corresponding decrease in calcium content in the metaphyseal and epiphyseal areas of both the operated and the control bone was highly significant. The mean values for hydroxyproline in plated and control bones remained largely unchanged.

Animals↗

Transient liver hypoxia after liver hilus dearterialization.

Dearterializaton of the liver causes changes which have been thought to be ischaemic in nature. Previous reports of direct measurements of liver tissue gas tensions have been confined only to the acute postoperative phase. In this study 15 dogs underwent a standardized and angiographically controlled liver hilus dearterialization with (6 dogs) or without (9 dogs) cholecystectomy. Six dogs underwent a sham operation and were used as controls. Liver respiratory gas tensions were measured with a Silastic tonometer intraoperatively during the first 90 minutes after dearterialization and on the first and seventh day postoperatively. Six dogs died, only one of these being in the dearterialization and cholecystectomy group. Liver pO2 decreased from the mean of 33.2 mmHg to a level of 15--20 mmHg in 20 minutes (p less than 0.05) during room air breathing. On the next day the liver pO2 values were normal. There was no difference in pO2-Values between the cholecystectomy and the noncholecystectomy groups. Liver pCO2 increased from the mean of 26.4 mmHg to 55--60 mmHg in the same time (p less than 0.05). However, on the first postoperative day normal values were seen only in the cholecystectomy group. 60% oxygen breathing prevented the changes in both liver pO2 and pCO2. No changes were noted in the liver gas tensions of the sham-operated dogs, not in the systemic arterial pO2 and pCO2 of the dearterialized animals. Thus a transient hypoxic state developed after this operation, which lasted for less than one day. This hypoxia may be prevented by 60% oxygen breathing postoperatively.

Animals↗

Microsomal hexobarbital metabolizing enzymes in regenerating cholestatic rat liver.

Microsomal changes were studied in regenerating liver cholestatic rats by measuring hexobarbital metabolzing capacity (HMC) in vitro. Total extrahepatic biliary obstruction was induced by ligating the common duct, 3 days later, a 70% liver resection was performed. Sham-operated animals served as controls. Analysis of HMC showed a similar pattern of microsomal regeneration in cholestatic as in sham-operated rats. This indicates that in the rat, cholestasis per se does not interfere with the development of this enzyme system during regeneration.

Alkaline Phosphatase↗

Peptic ulceration in kidney transplantation.

Gastroduodenal ulceration occurred in 45 patients during the post-transplantation period in a series of 500 transplantations of 434 patients. The mortality rate of this complication was high, 42%. Bleeding and perforation were the main problems. These complications occurred frequently during treatment for acute rejection. Present day prophylaxis, which is based on the use of antacids, seems to be inadequate for controlling these complications. Other possibilities for reducing the incidence of gastroduodenal ulceration in transplant patients are discussed. Since increased serum gastrin concentrations are often observed in these patients, prophylactic treatment should be based on preoperative evaluation of gastric secretion and serum gastrin determinations. The new histamine (H2) blocking agents should be evaluated in these patients.

Cimetidine↗