Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recovery from hyperglycemia was observed in streptozotocin diabetic mice that received subcutaneous, isogeneic transplants of either isolated islets or duct-ligated pancreas. Transplants of isolated islets obtained from collagenase-digested adult pancreas provided recovery from hyperglycemia, but the incidence of recovery depended on the amount of islet tissue initially transplanted. Hyperplastic, insulin-rich islets obtained from the pancreas of obese hyperglycemic mice (ob/ob) allowed recovery between 3 and 6 weeks, whereas an equivalent number of islets obtained from non-obese, normal donors gave only partial recovery after 8 weeks. Implantation of pancreatic endocrine tissue obtained from adult donors whose pancreatic ducts were ligated several weeks earlier, led to consistent recovery within 8 to 10 weeks. The content of immunoreactive insulin (IRI) extracted from transplants of mice recovering from hyperglycemia was 16 to 19% of that found in the normal mouse pancreas and was about 4 times greater than that remaining in the recepient's own pancreas. Transplants removed from hosts that did not recover contained a relatively small amount of IRI indicating that these transplants contained insufficient insulin stores to allow recovery form hyperglycemia.
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PMID:Subcutaneous, isogeneic transplantation of either duct-ligated pancreas or isolated islets in streptozotocin diabetic mice. 13 42

Intraperitoneal transplantation of collagenase-digested, isogeneic, neonatal rat pancreatic tissue successfully reversed streptozotocin-induced diabetes in 77% of recipients. The low serum immunoreactive insulin, hyperglycaemia, glycosuria and weight loss, characteristic of the diabetic animal, were corrected and the reduced activities of hepatic glucokinase and pyruvate kinase, and the low glycogen concentration of the liver of diabetic rats were restored to normal. Forty-three per cent of the successfully transplanted rats became normoglycaemic within 1 month of transplantation whereas 57% took from 1 to 6 months to achieve normoglycaemia and displayed a mild glucose intolerance when subjected to a glucose load. The rats which had not become normoglycaemic 6 months after transplantation showed some amelioration of the diabetic state, as shown by increased serum immunoreactive insulin and hepatic glycogen concentration and a slow weight gain compared with diabetic controls.
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PMID:Neonatal islet cell transplantation in the diabetic rat: effect on hepatic enzyme activity and glucose homeostasis. 14 94

Partially purified beta cell monolayer cultures were prepared from the pancrease of neonatal Wistar rats by dissociating the cells with a trypsin-collagenase solution. The cultures were grown in medium 199 containing a 10% fetal calf serum and 100 or 300 mg/100 ml glucose. Insulin release from the primary cultures during 12 days was 15 to 20 microunit/culture/day when the cells were grown in the medium containing 300 mg/100 ml glucose. When glucose concentration in the medium was decreased from 300 to 100 mg/ml insulin release fell to 2--5 microunit/culture/day. Theophylline stimulated insulin release in a short-time experiment. Transplantation of a 6--8-day culture in diabetic rats reduced the blood glucose concentration for 1 to 2 days.
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PMID:[Monolayer culture of pancreatic beta cells of newborn rats: Insulin secretion in vitro and attempt at beta-cell transplantation in experimental diabetes]. 15 May 94

Elucidation of the role of Ca2+ in the secretion of insulin and glucagon is complicated by the presence of different types of cells in the pancreatic islets. Visualization of calcium in sections of guinea pig pancreas with the histochemical reagent glyoxal bis-2-hydroxyanil revealed the most intense staining in the endocrine part but no differences between various islet cell types. A procedure for eliminating the majority of the beta-cells by streptozotocin injection in the guinea pig enabled a comparison of collagenase-isolated islets rich in alpha 2-cells with islets from untreated animals rich in beta-cells. The latter islets contained 24.6 +/- 2.4 mmol calcium/kg dry wt, as estimated by flameless atomic absorption spectrophotometry. This is twice as much as noted for the exocrine pancreas or the islets rich in alpha 2-cells. After storage for 3 days in culture medium, the two types of islets contained similar amounts of calcium. The cultured islets displayed differences related to cellular composition when measuring the incorporation of 45Ca into a lanthanum-nondisplaceable (intracellular) pool. In the presence of 3 mM glucose, more 45Ca was incorporated into the islets rich in alpha 2-cells. Increasing the glucose concentration to 20 mM with or without further addition of 30 U/liter bovine insulin was without effect on the 45Ca uptake into the islets rich in alpha 2-cells but stimulated that into islets rich in beta-cells. The different calcium dependence on glucose in the two types of islets may indicate that increased uptake of Ca2+ is a component of the mechanism for the secretion of both insulin and glucagon.
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PMID:Evidence for divergent glucose effects on calcium metabolism in pancreatic beta- and alpha 2-cells. 15 70

An enzymatic method is described for isolating intact parenchymal cells from rat livers. 3--4 g cells (wet weight) could be isolated from livers of rats weighing 180--230 g. After an in vitro preperfusion of 15 minutes with a Ca-free buffer, collagenase (200 mg/1) and calcium chloride (5.2 mmol/1) were added. Perfusion was continued for another 15 minutes at 37 degrees C. Micromorphological integrity of cell membranes was demonstrated by scanning electron microscopy. With regard to rates of gluconeogenesis and protein synthesis, parenchymal cells isolated according to our method were found to be superior to liver slices and cells isolated by other methods. Ratios of ATP/ADP (5.69) and of lactate/pyruvate (8.64) as parameters of the energetic situation and the redox state resp. were found within the physiological range. Integrity of cell surface receptors was proved by their sensitivity to epinephrine, glucagon and insulin. Glucagon (0.3 mumol/1) and epinephrine (1 mumol/1) and reduced glycogen deposition in hepatocytes of fasted rats by 84.9 % and 95.9 % resp. Both hormones stimulated glycogenolysis in parenchymal cells of fed rats to a similar extent. Urea synthesis was stimulated 29.5 % by glucagon (1 mumol/1), and inhibited 28.0 % by insulin (10 nmol/1). The stimulatory effect of glucagon (1 mumol/1) was abolished by insulin (10 nmol/1).
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PMID:[Isolation of intact liver parenchymal cells by a modified enzymatic method]. 16 41

An organ culture method suitable for the maintenance of viable human breast cancer for at least 14 days has been described. This method was applied to a total of 94 breast cancer specimens. It allowed good survival of "soft" tumors of various histological types, with loose connective stroma even in hormone-free medium. In contrast, "scirrhous" cancers showed poor survival in hormone-free medium; viable cells were maintained only at the very periphery of the explants. Supplementation of the medium with insulin (10 mug/ml), ovine prolactin (5 mug/ml), and hydrocortisone (1 mug/ml) in various combinations seemed to induce enlargement of viable cancer cells and moderate loosening of the stroma in some cases. However, it did not improve the survival of central tumor cords in scirrhous explants. Further supplementation of the medium with 17 beta-estradiol (minimum effective dose, 0.1 to 10 ng/ml), although it did not affect soft tumors, markedly improved survival of the cancer cells of scirrhous tumors throughout the whole explants, with evidence of collagen digestion around the neoplastic cells. This was observed in 18 of 20 scirrhous cancers subjected to this treatment. Estradiol need not be present during the whole culture period; the results at 14 days were identical in explants treated with estradiol for the first 7 days only or for the entire period. Addition of purified collagenase during the first 24 or 48 hr of culture resulted in complete dissolution of the collage. After such treatment, culture under the usual conditions resulted in excellent survival of the explants without improvement from hormone supplementation; thus, while estradiol was necessary when collagen was present, it was not longer required after collagen digestion. It can be concluded that breast cancer cells in organ culture are only slightly, or not at all, hormone dependent for survival, provided that they are not restrained by a dense collagen barrier. The estrogen-induced changes allowing survival inside the scirrhous explants strongly suggest the presence of an estrogen-dependent collagenolytic enzyme system in the collagen-rich breast cancers. This system could represent an important component of the hormone dependency of human breast cancer growth.
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PMID:Estradiol-dependent collagenolytic enzyme activity in long-term organ culture of human breast cancer. 16 44

In order to study the oeffect of somatostatin on the endocrine pancreas directly, islets isolated from rat pancreas by collagenase were incubated for 2 hrs 1) at 50 and 200 mg/100 ml glucose in the absence and presence of somatostatin (1, 10 and 100 mg/ml) and2) at 200 mg/100 ml glucose together with glucagon (5 mug/ml), with or without somatostatin (100 ng/ml). Immunologically measurable insulin was determined in the incubation media at 0, 1 and 2 hrs. Insulin release was not statistically affected by any concentration stomatostatin. On the other hand, somatostatin exerted a significant inhibitory action on glucagon-potentiated insulin secretion (mean +/- SEM, mu1/2 hrs/10 islets: glucose and glucagon: 1253 +/- 92; glucose, glucagon and somatostatin: 786 +/- 76). The insulin output in th epresence of glucose, glucagon and somatostatin was also significantly smaller than in thepresence of glucose alone (1104 +/- 126) or of glucose and somatostatin (1061 +/- 122). The failure of somatostatin to affect glucose-stimulated release of insulin from isolated islets contrasts its inhibitory action on insulin secretion as observed in the isolated perfused pancreas and in vivo. This discrepancy might be ascribed to the isolation procedure using collagenase. However, somatostatin inhibited glucagon-potentiated insulin secretion in isolated islets which resulted in even lower insulin levels than obtained in the parallel experiments without glucagon. It is concluded that the hormone of the alpha cells, or the cyclic AMP system, might play a part in the machanism of somatostatin-induced inhibition of insulin release from the beta-cell.
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PMID:Somatostatin-induced inhibition of insulin secretion from isolated islets of rat pancreas in presence of glucagon. 16 38

The inhibitory actions of somatostatin (100 ng./ml.) on insulin release, stimulated by high glucose (20 mM), and on glucagon release, stimulated by arginine (15 mM), were studied with two in vitro systems: the isolated perifused rat islets prepared by the collagenase procedure and the isolated perfused rat pancreas. Suppression of arginine-induced glucagon release by glucose (20 mM) and glyceraldehyde (5 mM) was also assessed in both systems. With the perfused pancreas, somatostatin caused 32 per cent inhibition of glucose-mediated insulin release and inhibited arginine-induced glucagon release by 72 per cent. In the same system, glucose and glyceraldehyde were similarly potent inhibitors of arginine-induced glucagon secretion. In contrast to the isolated perfused pancreas, there was no significant somatostation suppression of glucose-induced insulin release or arginine-induced glucagon release whether the inhibitor was present prior to or was added during stimulation by glucose or arginine. Furthermore, glucose was only minimally active and glyceraldehyde ineffective in inhibiting glucagon secretion due to arginine in the perifusion system. The most plausible explanation for the difference in the endocrine response of islet cells in the two types of widely used in vitro systems is that the alpha and beta cells have lost inhibitory receptors in the plasma membrane as a result of the collagenase isolation technic.
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PMID:Comparison of alpha- and beta-cell secretory responses in islets isolated with collagenase and in the isolated perfused pancreas of rats. 17 Nov 90

Pancreatic islets of wistar rats, isolated after 15 min of digestion with collagenase, secreted insulin in response to 15.0 mM glucose within 2 min and showed the typical sigmoidal glucose response during an incubation time of 15 and 60 min, respectively. Islets, isolated after 35 min of digestion with collagenase, responded with delay after stimulation with glucose (after 15 min of incubation), and are characterized by an increased "release" in the presence of 2.5 mM glucose.
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PMID:[The effect of preparative pancreatic digestion with collagenase on the glucose stimulated insulin secretion of isolated Langerhans islets]. 17 95

A human pancreatic beta cell tumor was maintained in monolayer cell culture for 80 days. The culture was terminated because of bacterial infection. Probably because extensive trypsin-collagenase dissociation was unnecessary, the dissociated cells attached much more quickly to the surface of the culture flask than do rat pancreatic cells obtained by enzymatic dissociation. Insulin release not only oscillated widely during the first 40 days of culture but also showed a decline from 380 mU the first week to about 50 mU/week the seventh week. For some unknown reason fibroblast overgrowth was not a major problem. Reduction of the medium glucose concentration from 16.5 mM to 5.5 mM did not alter insulin release rate. At glucose concentration of 16.5 mM, somatostatin 1.0 mug/ml reduced insulin release by 40%. From our previously reported studies on the effect of somatostatin on insulin release by monolayer cell cultures of rat endocrine pancreas, we conclude that the constant release of insulin by the tumor cells is relatively nonstimulated. We have confirmed that monolayer cultures of human pancreatic beta cell tumor do not represent a good model for normal human beta cell function because of the major shortcoming of an apparent inability to recognize glucose as a secretogogue.
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PMID:Monolayer cell culture of human pancreatic beta cell tumor: effect of glucose and somatostatin on insulin release. 17 3


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