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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Exponentially growing rat islet cells (RINr) and hamster islet cells (HIT T-15) were incubated in presence of tolbutamide (10-1000 microM), gliclazide (0.1-10 microM) or glibenclamide (0.01-10 microM) for 15 hrs. Accumulation of insulin in culture medium was estimated by RIA. Effects of sulfonylureas (SU) on cell proliferation were assessed by 3H-thymidine (3H-T) incorporation into cellular DNA. All of SUs used stimulated insulin production in RIN and HIT cell cultures (with an exception of tolbutamide, which markedly suppressed insulin secretion in HIT cells at 1000 microM). 3H-T incorporation into RIN cells was elevated only in presence of gliclazide (10 microM), whereas tolbutamide at 1000 M significantly inhibited RIN cell proliferation. Gliclazide (0.1 microM) and glibenclamide (0.01-10 microM) enhanced 3H-T incorporation into HIT cells. Further detailed investigations of mechanisms of SU effects on islet cell reproduction will be of use for designing optimal strategy of hypoglycemizing therapy of diabetes mellitus.
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PMID:[The insulin-secreting and proliferative activity of established islet cells in the presence of sulfonylurea]. 128 6

Since their demonstration in 1975, ICSAs have been proposed as serological markers and pathogenic elements in IDDM. ICSAs are detected in the sera of most newly diagnosed IDDM patients by indirect IFL that uses viable preparations of rat islet or insulinoma cells as substrate, but they also can be detected by using human insulinoma or fetal islet cells. We have tried to demonstrate ICSAs in the sera of 31 newly diagnosed diabetic patients, including 6 positive samples on human fetal islet cells, which used their natural target for the first time: normal human islet cells. In spite of using different types of preparations of these cells (i.e., freshly dispersed cell suspensions, monolayer cultures, or dispersed islets after culture), ICSAs could not be detected by IFL under the UV microscope, nor by flow cytometry. In contrast, 9 of 29 of the sera gave a positive staining on the RIN rat insulinoma cells. In an attempt to establish whether the putative ICSA autoantigen is present in the surface of human islet cells in the diabetic pancreas, the insulitis microenvironment was emulated by exposing the islets to three types of stress: 1) cytokines (IFN-gamma and TNF-alpha); 2) heat shock; and 3) hyperglycemia. However, diabetic sera failed again to recognize membrane antigens on the islet cells after either of these treatments. Neither were islet cells from a newly diagnosed diabetic patient stained by its autologous serum (ICA titer > 80 JDF U). These results suggest that ICSA autoantigen is not expressed in the membrane of human islet cells and therefore raises doubts about their proposed pathogenic role.
Diabetes 1992 Dec
PMID:Reevaluation of autoantibodies to islet cell membrane in IDDM. Failure to detect islet cell surface antibodies using human islet cells as substrate. 144 4

At present, only islet cell lines of animal origin have been successfully generated (e.g. RIN, HIT). A fully differentiated human beta cell line would be advantageous for diabetes research. We now report the generation of a human endocrine pancreatic cell line obtained by transfection using a plasmid containing the early region of SV40 viral DNA. Viral integration and transcription was assessed by Southern and Northern blotting. This cell line has been growing continuously for more than 2 years and maintains several of the characteristics of the parental cells from which they were generated. The presence of Neuron Specific Enolase, Protein Gene Product 9.5, cytokeratin, microvilli, cytoplasmic electrodense granules and the secretion of insulin, glucagon and somatostatin supports the neuroendocrine origin of this cell line. However, hormone production progressively decreased and finally stopped at passage 8. Flow cytometric analysis showed that HLA expression in this cell line is readily induced by IFN-gamma and modulated by TNF-alpha. The establishment of this human endocrine cell line indicates the feasibility of immortalizing human islets by transfection with viral oncogenes. To obtain a fully differentiated cell line it may be necessary to use other DNA constructs which immortalize the cells without fully transforming their phenotype.
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PMID:Transfection with SV40 gene of human pancreatic endocrine cells. 168 Mar 32

To investigate the target antigen(s) recognized during the autoimmune process in insulin-dependent diabetes mellitus (IDDM), we produced human monoclonal antibodies by Epstein-Barr virus transformation of peripheral blood lymphocytes from a large number (n = 50) of newly diagnosed IDDM patients. Screening by indirect immunofluorescence assay, using the RINm5F rat insulinoma cell line and eight other human or rat tumour cell lines, was performed to identify monoclonal antibodies that reacted with either membrane or cytoplasmic antigens. Eighteen IgM monoclonal antibodies reacting with cytoplasmic antigens of RIN cells were obtained; 14 of them also showed a staining of the cytoplasm of various non-beta-cell lines, while four displayed a binding restricted to beta-cells among the panel tested. However, among three monoclonal antibodies reacting with the membrane of RIN cells, one (HMD-1) produced an IgG antibody with a binding restricted to the membrane of beta-cells (RIN, HIT, and normal rat islet cells). The membrane antigens of HMD-1 were identified in Western blotting as proteins with molecular weights of 64 and 70 kD. This antibody had no apparent cytotoxic effect on RIN cells. These data suggest that, apart from 'natural autoantibodies,' it is feasible to obtain human monoclonal antibodies from IDDM patients that bind specifically to the beta-cell cytoplasm or to the beta-cell membrane.
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PMID:Monoclonal autoantibodies from insulin-dependent diabetic patients: autoantibodies against beta-cell surface or cytoplasmic antigens. 169 82

Previously it has been shown that glucagon-like peptide (GLP)-1(7-36)amide stimulates insulin secretion from tumoral RIN m5F cells by activation of adenylate cyclase. However, its mechanism in normal islets is not established. We therefore examined the effects of GLP-1(7-36)amide in isolated, overnight cultured, normal rat islets. GLP-1(7-36)amide (greater than or equal to 10(-9) M) stimulated insulin secretion by augmenting both the efficacy and potency of glucose over a wide dose-range of glucose (3.3-16.7 mM). The first 15 min of GLP-1(7-36)amide-stimulated insulin secretion was independent on extracellular Ca2+, whereas a sustained insulin secretion was seen only in the presence of extracellular Ca2+. Concurrently with this, GLP-1(7-36)amide sustainely stimulated 45Ca(2+)-efflux from prelabelled islets only in the presence of extracellular Ca2+, whereas after removal of extracellular Ca2+, the peptide stimulated only a slight 45Ca(2+)-efflux during the first 15 min. GLP-1(7-36)amide also stimulated 86Rb(+)-efflux from prelabelled islets, but in contrast to 45Ca(2+)-efflux, the 86Rb(+)-efflux was not reduced by removal of extracellular Ca2+. GLP-1(7-36)amide had no influence on 3H-efflux from myo-[2-3H]-inositol prelabelled islets. Moreover, the inhibitor of protein kinase C (PKC), staurosporine, did not affect GLP-1(7-36)amide-stimulated insulin secretion. The results show that the first phase of GLP-1(7-36)amide-stimulated insulin secretion is independent on extracellular Ca2+, whereas the sustained phase of GLP-1(7-36)amide-stimulated insulin secretion requires extracellular Ca2+. In contrast, phosphoinositide hydrolysis and PKC are not involved in the signal transduction pathway stimulated by GLP-1(7-36)amide in normal islets.
Diabetes Res 1991 Apr
PMID:GLP-1(7-36) amide stimulates insulin secretion in rat islets: studies on the mode of action. 180 86

The effects of the cytokines tumor necrosis factor-alpha and interferon-gamma on the adult beta-cell have been well described: a reduction of insulin secretion and content and death of the cell. For this reason and because these cytokines may be released from activated lymphocytes and macrophages that infiltrate islets in insulin-dependent diabetes, they have been implicated in the pathophysiology of this form of diabetes. As to whether the human fetal beta-cell, which differs from the adult beta-cell in not releasing insulin in response to the nutrient glucose and not being adversely affected by the toxin streptozotocin, is similarly affected is unknown. To examine this question we cultured monolayers of a single cell suspension of human fetal pancreas in the presence or absence of 1000 U/mL of these cytokines for 7 days. Chronic insulin release was enhanced for the first 2 days of culture, but unchanged thereafter. Acute insulin release in response to the secretagogue theophylline (10 mM) was enhanced on day 7, but not earlier. There was an increase in the insulin content of the cells by the fourth day, probably due to an increase in the number of beta-cells present (45 +/- 5% vs. 22 +/- 3%). Microscopically, non-beta-cells also seemed to increase in number; there was an increase in both DNA and cell number by the seventh day. In contrast to these beneficial effects on the human fetal beta-cell, treatment of adult rat insulinoma cells, represented by RIN-m5F cells, resulted in inhibition of insulin secretion during the first day of culture and subsequent death of 86% of the cells by the sixth day of culture. It is hypothesized that the functional immaturity and lack of normal (adult) metabolic activity of the human fetal beta-cell somehow confers protection on these cells from the cytotoxic effects of tumor necrosis factor-alpha and interferon-gamma. Indeed, our findings suggest that these cytokines may be trophic for the developing beta-cell.
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PMID:Role of tumor necrosis factor-alpha and interferon-gamma as growth factors to the human fetal beta-cell. 193 17

Five low doses (40 mg.kg-1.day-1) of streptozotocin were given to CD-1 mice to induce "immune" diabetes with insulitis. T-splenocytes (L3T4+ and Lyt2+) from streptozotocin-treated mice were previously reported to display in vitro an increased binding for Beta cells, preceding the onset of hyperglycaemia and of insulitis. Since heparin inhibits lymphocyte traffic, displays anti-adhesive properties, and attenuates some cell-mediated immune diseases, we have investigated the effects of heparin and N-desulphated heparin: 1) in vivo on low-dose streptozotocin-induced diabetes and insulitis, and 2) in vitro on the increased binding of T-splenocytes from streptozotocin-treated mice to rat insulinoma (RINm5F) cells. Daily subcutaneous low doses (5 micrograms or 10 micrograms) of heparin induced a delay in onset and a reduction of the severity of hyperglycaemia and insulitis (p less than 0.01), and reduced the incidence of diabetes (p less than 0.01). Similar effects were obtained with 5 micrograms daily doses of N-desulphated heparin devoid of anticoagulant activity. In contrast, lower (1 microgram) or higher (200 micrograms) doses of heparin were ineffective. Heparin (10 micrograms) did not modify the "toxic" diabetes induced by a single high dose (200 mg/kg) of streptozotocin. On the other hand, heparin dose-dependently (0.1 microgram/ml to 500.0 micrograms/ml) inhibited the increased binding of splenocytes from streptozotocin-injected mice to RIN cells as compared to splenocytes from control mice. This in vitro anti-adhesive effect was detected when either splenocytes or RIN cells were pretreated with heparin before their co-incubation, and was also obtained with N-desulphated heparin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Heparin attenuates low-dose streptozotocin-induced immune diabetes in mice and inhibits the beta-cell binding of T-splenocytes in vitro. 206 56

An enzyme-linked immunosorbent assay (ELISA) has been developed to detect antibodies against surface components of rat islet and spleen lymphocytes. Live islet tumor RIN5 AH cells expressing characteristic ganglioside target antigens or rat spleen cells were immobilized onto wells of microtiter polystyrene plates precoated with poly-l-lysine and then incubated with test or normal rat sera. Cell surface-bound antibodies were quantitated after reaction with horseradish peroxidase-conjugated rabbit anti-rat Ig. With this assay, 46% (6/13) of sera from diabetes-prone BB rats and 100% (8/8) of sera from rats treated with complete Freund's adjuvant/streptozotocin (CFA/STZ) prior to immunization with RIN cells had islet cell surface antibodies: 54% (7/13) and 75% (6/8), respectively, were positive for lymphocyte antibodies (defined as the HRP anti-rat Ig binding exceeding the mean + 2SD of control group values). SDS polyacrylamide gel electrophoresis followed by immunoblotting analysis suggested that the islet cell antibodies in sera from the BB and CFA/STZ rats recognized RIN-cell components that were different in their molecular weights. These antigens were not detectable on spleen cells indicating that the ELISA described can be used to quantitate levels of islet cell specific antibodies which possibly reflect beta cell damage with progression to islet degeneration in the rat.
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PMID:Detection of antibodies to islet cell and splenic lymphocytes in diabetes-prone BB and adjuvant-streptozotocin treated Lewis rats by ELISA and immunoblot analysis. 209

Growth hormone (GH) plays a dual role in glucose homeostasis. On the one hand, it exerts an insulin antagonistic effect on the peripheral tissue, on the other hand, it stimulates insulin biosynthesis and beta-cell proliferation. The expression of GH-receptors on the rat insulinoma cell line RIN-5AH-T2-clone B was studied. The binding characteristics with regard to specificity for the native 22 kDa hGH, and the 20 kDa variant were similar to that reported on rat adipocytes. Normal rat islet cells showed a similar affinity for hGH. The RIN cells express GH receptors similar to the cloned liver receptor. It is hypothesized that defects in the receptor expression on the beta-cells may contribute to the susceptibility to develop diabetes.
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PMID:Expression of the growth hormone receptor gene in insulin producing cells. 209 87

Splenocytes from low-dose (40 mg.kg-1.day-1) streptozotocin-treated mice were tested for their binding ability to rat insulinoma (RINm-5F) cells in a rosette-forming cell assay, before and during the onset of diabetes. They displayed a higher (p less than 0.0001) RIN-adherence than control splenocytes. Such an enhanced binding of splenocytes from diabetic mice was observed on another B-cell (HIT cell) line, but not on non-B cells (particularly on exocrine pancreatic cells, endocrine cells or natural killer-target cells), suggesting that the increased RIN-binding is B-cell specific. This B-cell specificity was also suggested by the use of increasing splenocytes/RIN ratios showing a saturation of RIN-binding in streptozotocin-treated mice. Depletion of lymphocyte subsets revealed that supernumerary RIN-adherent splenocytes from diabetic mice were mainly T lymphocytes, involving both L3T4+ and Lyt2+ cells. Overall, the increased splenocyte-RIN binding was concomitant with the occurrence of islet destruction, but preceded the onset of hyperglycaemia by five days and even the islet immune infiltration. An increased number of RIN-binding splenocytes was also found in mice treated with 33 mg.kg-1.day-1 of streptozotocin, displaying insulitis but not hyperglycaemia. This phenomenon was not found with splenocytes from mice displaying a "toxic" diabetes induced by a single high dose of streptozotocin. No correlation could thus be found between numbers of RIN-binding splenocytes and blood glucose levels, indicating that this phenomenon was not due to metabolic disturbances. These data describe a new marker of cellular immunity in this animal model.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:B cell-adherent splenocytes precede the onset of diabetes in low-dose streptozotocin-treated mice. 213 23


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