Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

By perfusion of the isolated human liver with collagenase and hyaluronidase a mixed suspension of various cell types was obtained. Pure parenchymal cells were prepared by differential centrifugation, pure non-parenchymal cells by the use of pronase and subsequent isopycnic centrifugation on metrizamide gradients (50-300 g/l). About 90% of the parenchymal and non-parenchymal cells were viable as judged by trypan blue staining. Non-parenchymal cells were not capable fo gluconeogenesis but at high rates. Parenchymal cells retained their ability to form glucose and to accumulate glycogen from fructose greater than lactate/pyruvate greater than alanine. Studies on binding of 125I-labelled insulin by isolated parenchymal cells were performed at 30 degrees C. The binding data may fit with a minimum of two classes of binding sites: (a) high affinity--low capacity sties (Kd approximately 6.6 nmol/l, capacity approximately 16 000 insulin molecules per cell) and (b) low affinity-high capacity sites (Kd approsimately 0.37 mumol/l, capacity approximately 646 000 molecules per cell).
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PMID:Preparation of parenchymal and non-parenchymal cells from adult human liver--morphological and biochemical characteristics. 100 13

A method is described for the dissociation of mouse ovaries and the isolation of oocytes free of somatic cells by agitating pieces of ovary in collagenase and deoxyribonuclease in a calcium and magnesium free salt solution. This method yielded about 50% of the growing oocytes from immature mice. The utilization of exogenously administered 14C-labelled energy sources by oocytes in various growth stages was determined by measurement of evolved 14CO2. Little or no evolution of 14CO2 was detected from oocytes of any size incubated in 14C-glucose, lactate or succinate. The production of 14CO2 from 14C-pyruvate increased logarithmically when plotted against increasing oocyte volume with a plateau occurring after occytes reached a volume of 65,500 mum3 (50 mum diameter). Thus, the pattern of energy metabolism for oocyte maturation and early egg cleavage, wherein glucose and lactate are not utilized as efficiently as pyruvate, has been established by the earliest stages of oocyte growth.
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PMID:Analysis of mouse oogenesis in vitro. Oocyte isolation and the utilization of exogenous energy sources by growing oocytes. 100 46

Perfusion of growth hormone inhibitory factor (somatostatin) into rat pancreas inhibited secretion of glucagon and insulin into medium containing 5.5 mM glucose. A 15-min infusion of arginine (20 mM) greatly increased glucagon and insulin secretion. When perfused simultaneously with arginine, somatostatin (55 nM) abolished the increase in glucagon secretion. The acute phase of insulin secretion in response to arginine was attenuated by somatostatin, and subsequent secretion was decreased to control levels. Pretreatment for 5 min with somatostatin blocked even acute-phase insulin secretion in response to arginine. Somatostatin did not affect basal or glucose-stimulated secretion of insulin from rat pancreatic islets isolated by the collagenase technique. Arginine-stimulated secretion of insulin was enhanced by somatostatin in isolated islets. These results demonstrate a direct effect of somatostatin on the pancreas to inhibit secretion of glucagon and insulin. The failure of somatostatin to inhibit insulin secretion in pancreatic islets may be due to alterations in the beta cells produced by the isolation procedure. It is also possible that the effect of somatostatin on insulin secretion may be mediated indirectly.
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PMID:Inhibition of glucagon and insulin secretion by somatostatin in the rat pancreas perfused in situ. 108 35

The in vitro effect of alloxan exposure on the permeability of collagenase isolated rat pancreatic islets to sucrose, D-mannitol, and L-glucose has been investigated. Determination of changes in cell volume with a non-wash double label isotope procedure indicates that alloxan treatment exerts no measurable effect on permeability to sucrose, D-mannitol, or L-glucose as compared to nonalloxan-treated islets. In addition, neither prior exposure nor the concomitant presence of alloxan alters the rate of D-glucose or 3-0-methyl-D-glucose transport into rat pancreatic islets. It is concluded that the in vitro effect of alloxan on abolishing glucose-induced insulin release in isolated rat pancreatic islets does not appear to be the result of permeability changes to small organic molecules or alteration in the transport of D-glucose into the beta-cell.
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PMID:Effect of alloxan on permeability and hexose transport in rat pancreatic islets. 109 63

The biosynthetic activity of the B-cells of obese hyperglycemic mice (obob) was measured by the incorporation of [3H]leucine into proteins in collagenase-isolated pancreatic islets. To quantitate the incorporation into proinsulin and insulin, an immune binding method was used. For this purpose, anti-insulin serum was coupled to cyanogen bromide-activated SepharoseR 4B. This turned out to be a specific and versatile technique for the measurement of newly synthesized proinsulin and insulin in the B-cells. The B-cells of obob mice appear to be well adapted to a high rate of hormone biosynthesis, since at 16.7 mM glucose 44% of [3H]leucine incorporated into TCA-precipitable proteins was bound to the insulin antibodies coupled to Sepharose 4B. The insulin biosynthetic rate was stimulated 9 times at 16.7 mM glucose, during a 3-h incubation, compared with the basal insulin biosynthesis rate.
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PMID:Anti-insulin serum coupled to Sepharose 4B as a tool for the investigation of insulin biosynthesis in the B-cells of obese hyperglycemic mice. 110 96

Pancreatic islets of mice were isolated by the collagenase method. After a preincubation period of 20 min they were incubated in Krebs-Ringer-albumin buffer in the presence of glucose. Concanavalin A (2 mg/ml) inhibits the glucose-induced release of insulin; this same property is shown by Concanavalin A bound to nonphagocytosable beads of Sephrose at lower concentrations (0.4 mg/ml). In pancreatic islets stimulated by tolbutamide, glibenclamide or arginine the secretion of insulin is not inhibited in the presence of Concanavalin A. The incorporation of tritiated leucine is not influenced by Concanavalin A. Since desialized pancreatic islets react in the same way the glucose-induced secretion of insulin appears to be a membrane-dependent process.
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PMID:Interactions of concanavalin A with isolated pancreatic islets. 110 13

The function of the pancreatic B-cell was studied in relation to the development of the diabetic syndrome in a new variety of the diabetic mutant mouse, which was produced at The Jackson Laboratory, Bar Harbor, Maine, U.S.A. by outcrossing of a c57bl/ksJ-db stock with C57BL/6J mice. The expression of the db-gene in the resulting strain was evaluated by measurements of the body weights and the concentrations of serum glucose and serum insulin at different ages of the animals. In the diabetic mice the body weights increased rapidly between 5 and 25 weeks of age to a weight twice that of the lean controls. During the same time hyperglycaemia and hyperinsulinaemia occurred, the maximal serum glucose and insulin values being observed between 17 and 25 weeks of age. Later on the serum glucose and serum insulin concentrations gradually decreased. Islets were isolated with collagenase from animals 5, 10 or 20 weeks old, and studied with respect to insulin content, glucose oxidation and the secretion and synthesis of insulin. The results were compared with data from control experiments with islets isolated from non-diabetic littermates. No major differences were found between islets from diabetic and control mice with regard to the glucose oxidation rate, whereas an exaggerated insulin response to glucose was observed in islets from 5 weeks old diabetic mice. In the 20 weeks old diabetic animals there was a significantly decreased islet insulin content and a considerably lowered insulin biosynthesis.
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PMID:Function of the pancreatic B-cell during the development of hyperglycaemia in mice homozygous for the mutations "diabetes" (db) and "misty" (m). 110 67

The surfaces of isolated pancreatic islet cells were studied with the scanning and transmission electron microscopes. Islets were isolated from the pancreas of Wistar rats by collagenase treatment and were incubated either in glucose-free medium or in 300 mg% glucose for one hour. Immunoreactive insulin (IRI) in the media of both control and experimental preparations was assayed. Islets were then transferred to 4% glutaraldehyde, buffered with cacodylate, pH 7.4, and prepared for scanning and transmission electron microscopy. Cell masses average 200 mu in diameter. Alpha cells appear pyramidal in shape, are about 8 mu in diameter and appear in groups. Beta cells are round or oval in shape and have an average diameter of 10 mu. Glucose stimulation raised the IRI value tenfold and increased the number of blebs and other surface irregularities per unit area of beta cell surface. Comparison with transmission electron micrographs suggests that the blebs are related to the process of emiocytosis.
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PMID:The surface structure of isolated pancreatic islet cells. 110 68

Using an in vitro rabbit pancreas system, we studied the effect of monoamine oxidase (MAO) inhibitors on flucose-stimulated insulin secretion. We evaluated the effect of both brief (15 min) and prolonged (60 min) exposure of pancreas segments to non-hydrazine (harmine, alpha-methyltryptamine, tranylcypromine and pargyline) and hydrazine (phenelzine, nialamide, iproniazid) type MAO inhibitors. All of the hydrazine type MAO inhibitors potentiated glucose-stimulated insulin secretion. Of the non-hydrazine inhibitors, only harmine and alpha-methyltryptamine potentiated glucose-stimulated insulin secretion. Hydrazine, although not itself an MAO inhibitor, also potentiated insulin secretion. Sixty minutes of exposure to tranylcypromine or alpha-methyltryptamine caused a decrease in insulin secretion. These MAO inhibitors are primary amines and primary amines can inhibit insulin secretion. The dopamine (DA) or serotonin (5-HT) content of the B-cells was increased by incubating rabbit pancreas with L-3, 4-dihydroxyphenylalanine (L-Dopa) or 5-hydroxytryptophan (5-HTP) for forty-five minutes prior to stimulation with glucose. Non-hydrazine MAO inhibitors increased dopamine inhibition of insulin secretion and either did not alter, or decreased serotonin inhibition of insulin secretion. Rabbit pancreatic islets were isolated using the collagenase digestion technique. The MAO activity of islet homogenates was determined using 5-HT and DA as substrates. Rabbit islet MAO has only one-tenth the specific activity against 5-HT (35 +/- 8.7 mumumoles/mg/min, M +/- SEM) that it has against DA (357 +/- 62.3 mumumoles/mg/min). This suggests that one reason that MAT inhibitors do not increase serotonin inhibition of insulin secretion is because MAO is not the major pathway for 5-HT inactivation in rabbit pancreatic islets. These studies suggest that MAO inhibitors alter insulin secretion, by both decreasing B-cell monoamine degradation and by mechanisms that do not involve MAO inhibition.
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PMID:Monoamine oxidase inhibitors: nature of their interaction with rabbit pancreatic islets to alter insluin secretion. 110 23

Procedures were developed for preparing partially purified beta cell monolayer cultures. Neonatal rat pancreases were dissociated with a trypsin-collagenase solution. Beta cells were separated from denser acinar cells by centrifuging the initial suspension in a two layer discontinous Ficoll gradient (20, 25%). Resultant cultures, highly enriched in beta cells, were further purified by incubation with cystine-free medium. This caused necrosis of the majority of fibroblastoid cells within two days, while beta cells were considerably less affected. The resultant cultures contained an average of 72% beta cells compared to 10% in untreated control cultures. Insulin release by purified monolayers remained responsive to changes in the glucose concentration of the culture medium.
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PMID:Pancreatic beta cell culture: preparation of purified monolayers. 111 78


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