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)

A new technique for pancreatic islet isolation, based on trypsin administered into the pancreatic duct system and a reduced amount of collagenase for digestion of the removed and chopped pancreatic tissue, yielded viable islets as judged by the metabolic response of 27 inbred, streptozotocin-diabetic rats after intraportal transplantation of the islets: all recipients of greater than 240 islets normalized their blood glucose, plasma insulin, urine volume and urinary glucose. The number of islets isolated was the same as with the conventional collagenase technique.
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PMID:Use of trypsin for isolation of islets of Langerhans in the rat. 20 69

To identify cells developing into adipocytes by accumulation of triglyceride, rat epididymal fat pad cells from small rats were exposed to (3)H-labeled chylomicron fatty acids in vivo and then liberated with collagenase. Tissue remnants were removed by filtration and mature fat cells by flotation. Aggregating cells were then removed by filtration through a 25- micro m nylon screen. Further purification of cells labeled in vivo was obtained by removing floating cells from those adhering to the bottom of a culture dish. The adhering cells multiplied to a confluent monolayer when cultured in Medium 199 containing serum, glucose, insulin, and a triglyceride emulsion. The cells then gradually enlarged due to granulation of the cytoplasm by a lipid-staining material. After about 2 weeks these granules had coalesced forming mature adipocytes of typical signet-ring appearance. Free adipocytes could then be recovered from the cultures by collagenase treatment. After about 2 weeks of culture these cells had the same size (about 30 micro m) as adipocytes recovered in the original collagenase preparation of the rat epididymal fat pad. They contained triglyceride lipase activity and incorporated glucose into triglycerides to the same extent as cells developed in vivo but had higher lipoprotein lipase activity. In vitro, heparin in a low concentration, prostaglandin E(1), isobutylmethylxanthine, and cholera toxin markedly promoted the development of these cells into adipocytes. This could be shown to occur almost completely indicating that this fraction of cells was homogeneous and consisted of cells with the capacity to form adipocytes. The duplication time was about 2 days and did not change with subculturing. Preadipocytes could be obtained by density gradient centrifugation, isolating triglyceride-containing cells either directly from the pad or after 3 days in culture. All of these cells developed into adipocytes as described above but did not multiply as readily. It was concluded that cells from the epididymal fat pad from small rats can be isolated in a homogenous fraction that develops in culture into cells of identical morphology and function as adipocytes formed in vivo. The differentiation of these cells into adipocytes may be manipulated in vitro.
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PMID:Isolation and characterization of cells from rat adipose tissue developing into adipocytes. 20 38

Glucose-induced insulin secretion is enhanced by a preceeding glucose stimulus. The characteristics of this action of glucose were investigated in perfused pancreas and collagenase-isolated islets of Langerhans. A 20- to 30-min pulse of 27.7 mM glucose enhanced both the first and second phase of insulin release in response to a second glucose stimulus by 76-201%. This enhancement was apparent as an augmented maximal insulin release response to glucose. The effect of priming with glucose was seen irrespective of whether the pancreatic tissue was obtained from fed or fasted rats. Separating the two pulses of hexose by a 60-min time interval of exposure to 3.3 mM glucose did not abolish the potentiation of the second pulse. Omission of Ca(++) as well as the inclusion of somatostatin or mannoheptulose during the first pulse abolished insulin secretion during this time period; however, only the inclusion of mannoheptulose deleted the potentiation of the second pulse. d-Glyceraldehyde, but not pyruvate, d-galactose, or 3-isobutyl-1-methylxanthine, could substitute for glucose in inducing potentiation. In islets labeled with [2-(3)H]adenine, the [(3)H]cyclic AMP response to glucose was increased by 35% when measured after 1 min, but was increased only marginally after 2-10 min of stimulation with a second pulse of glucose. The production of (3)H(2)O from glucose was not affected by glucose priming. It is concluded that (a) the induction of the glucose-induced, time-dependent potentiation described here is dependent on glucose metabolism but not on stimulation of cyclic AMP, calcium fluxes, or insulin release per se; (b) the mechanisms that mediate the pancreatic "memory" for glucose are unknown but do not seem to involve to a major extent an increased activity of the adenylate cyclase-cyclic AMP system of the beta-cell; (c) the evidence presented supports the hypothesis of a dual role of glucose for insulin release.
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PMID:Immediate and time-dependent effects of glucose on insulin release from rat pancreatic tissue. Evidence for different mechanisms of action. 20 21

In collagenase isolated rat pancreatic islets, CCK-PZ, SHG, secretin and glucagon stimulated the accumulation of cAMP, in physiological ranges. The resulting increment of cAMP showed a good correlation with insulin release stimulated by either glucagon or secretin, but not by SHG or CCK-PZ. In the same system, 14CO2 production from glucose-U-14C was significantly increased by either SHG or CCK-PZ. The results presented in this report are compatible with the hypothesis that insulin release by gastrointestinal hormones may be mediated by cAMP in the B-cell in the case of either glucagon or secretin; whereas, in the case of either SHG or CCK-PZ, it may presumably be mediated by an unknown mechanism in glucose metabolism, other than c-AMP.
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PMID:Stimulation by gastro-intestinal hormones of cyclic adenosine 3': 5'-monophosphate accumulation and insulin release in isolated pancreatic islets of the rat. 20 18

The metabolic response to repeated isologous transplantation of isolated pancreatic islets was studied in 11 streptozotocin-diabetic AGUS rats. The islets were isolated with collagenase and transplanted intra-portally in batches previously found to be quantitatively insufficient for reversal of the diabetic state. Primary transplantation caused a slight improvement whereas retransplantation with the same number of islets three weeks later was followed by normalization of blood glucose, plasma insulin, urine volume and urine glucose per 24 hours during a three-month observation period. Repeated isologous transplantation of isolated pancreatic islets has an additive effect on the metabolism in that two insufficient tissue doses correct streptozotocin induced diabetes in the rats.
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PMID:Repeated isologous transplantation of islets of Langerhans in the diabetic rat. 21 67

Fluxes of 86Rb+ and hydrolysis of p-nitrophenyl phosphate were measured in collagenase-isolated islets of diabetic C57BL/KsJ-db/db-mice and normal controls (C57BL/KsJ-+/+). Both types of islets accumulated Rb+ avidly, as originally reported for hand-dissected islets of non-inbred ob/ob-mice. KsJ-db/db-mouse islets showed enhanced accumulation of Rb+ and normal activity of K+-activated nitrophenyl phosphatase. D-glucose, 20 mmol/l, inhibited Rb+ efflux in normal islets but not in those from KsJ-db/db-mice. The glucose insensitivity of Rb+ efflux was observed in young animals, which exhibit glucose-induced insulin release, as well as in old animals, which do not secrete insulin in response to glucose. The anomalous regulation of Rb+ efflux already present in young animals may bear on the liability of KsJ-db/db-mouse B-cells to develop defective control of membrane potential, an abnormal metabolism of cyclic AMP, and a marked failure of insulin secretory capacity.
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PMID:86Rb+ fluxes and K+-stimulated nitrophenyl phosphatase activity in the pancreatic islets of genetically diabetic mice (C57BL/KsJ-db/db). 21 36

22 human pancreases were removed soon after circulatory arrest from donors aged 15--63 years. Part of the pancreas was used for isolation of islets by the collagenase technique. The mean yield +/- SEM, expressed as the number of islets isolated from 4 g pancreas was 79 +/- 15. The yield varied considerably even when the pancreas was removed immediately after circulatory arrest and the histology was normal, and there was no correlation with the age of the donors. The islet content of insulin (ng/microgram dry islet) was 8.5 +/- 1.2 (mean +/- SEM). Isolated islets were loaded with 45Ca in the presence of 20 mM glucose and placed in a perfusion apparatus for further studies of the 45Ca washout. The decrease of washout of radioactivity in Ca2+-deficient medium offers support for the existence of a Ca2+-Ca2+ exchange process. When added in a concentration of 20 mM, glucose tended to stimulate 45Ca efflux in perfusion medium of ordinary ionic composition but inhibited this process when the medium was deficient in Ca2+. Exposure to the calcium ionophore X-537A resulted in immediate stimulation of of 45Ca efflux from human islets as previously observed for islets from rats and mice. This suggests that Ca2+ has a direct regulatory role for insulin release also in humans.
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PMID:Collagenase isolation and 45Ca efflux studies of human islets of Langerhans. 21 85

The influence of histocompatibility on islet transplantation in dogs was studied. Donors and hosts were chosen by help of the macrophage-electrophoresis-mobility test. By subtotal pancreatectomy and twice applying streptocotocin diabetes was successfully induced in recipient animals. Isolation of pancreating islets from the donor was done by means of the collagenase method combined with the Ficoll-gradient-separating technique. The grafting occurred via portal vein into the liver. Significant decrease of blood sugar during 10 weeks was observed in animals with good compatibility. This effect lasted only 14 days in cases of bad compatibility. Concentrations of insulin in the portal vein and superior caval vein 4 weeks after grafting was lower in cases with high-grade histoincompatibility. The duration of functioning of transplanted islets depends on the histocompatibility.
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PMID:[Results of islet transplantation in diabetic dogs]. 21 71

Prolactin receptors were monitored by measuring 125I-labeled prolactin binding to collagenase-dissociated mammary epithelial cells of lactating BALB/c mice. Specific receptors for iodine-labeled prolactin with an apparent dissociation constant (Kd) of 0.99 . 10(-9) M were present on the dissociated mammary cells. The binding was inhibited by ovine prolactin, human growth hormone and human placental lactogen but not by follicle stimulating hormone, luteinizing hormone, thyroid stimulating hormone, bovine growth hormone or insulin. Adrenal ablation of nursing mothers caused a reduction of the number of prolactin receptors and this effect was preventable by hydrocortisone therapy. Hydrocortisone injections to mothers 3 days after adrenalectomy also induced a replenishment of the prolactin receptors on the mammary cells. Injections of progesterone failed to sustain the high level of mammary cell prolactin receptors in adrenalectomized animals. Stimultaneous injections of hydrocortisone and progesterone to animals 3 days after adrenalectomy caused a partial suppression of the stimulatory action of hydrocortisone alone. The results suggest that hydrocortisone can exert a modulatory influence on mammary cell prolactin receptors in non-hypophysectomized post-partum mice without altering the dissociation constant (Kd) of the receptors.
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PMID:Glucocorticoid modulation of prolactin receptors on mammary cells of lactating mice. 21 16

A method is described for isolation of plasmatic membranes of rat fatty cells immediately from fatty tissue without the treatment with collagenase. Homogenization of fatty tissue was carried out in large volumes of buffered sucrose and EDTA at room temperature followed by sucrose density gradient centrifugation. The preparations obtained exhibited high specific activity of the marker enzyme of plasmatic membranes [5'-nucleotidase and K+, Na+-ATPase], as well as high ability for specific binding of insulin.
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PMID:[Isolation of the plasma membranes of fat cells without using collagenase]. 22 73


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