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

Nitric oxide, a radical generated by the enzyme nitric oxide synthase (iNOS), may be an important mediator of beta-cell damage in early insulin-dependent diabetes mellitus. We have investigated the molecular regulation of iNOS in insulin-producing RINm5F cells. The data obtained suggest that iNOS is maximally induced in these cells by a 6-h exposure to IL-1 beta or TNF-alpha + IFN-gamma, but not by endotoxin. iNOS mRNA degradation is rapid and it is not affected by IL-1 beta. Interestingly, NO seems to induce a negative feedback on iNOS expression, probably by decreasing iNOS transcription.
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PMID:Studies on the molecular regulation of the inducible form of nitric oxide synthase (iNOS) in insulin-producing cells. 753 33

We have used a reverse transcriptase-polymerase chain reaction (RT-PCR) protocol to examine the expression of cytokines in the pancreases and islets of patients with type I diabetes. We detect a significant increase in the level of expression of interferon (IFN)-alpha in the pancreases of the diabetic patients as compared with the control pancreases. In contrast, IFN-beta was detected at comparable levels in both groups, while IFN-gamma was detected in three of four control pancreases and one of four pancreases from the diabetic individuals. The IFN-alpha cDNAs generated by the RT-PCR were cloned and sequenced to determine which alpha-subtypes were being expressed. We found that the repertoire of subtypes was quite limited in any one individual (diabetic or not), although each individual was different with respect to the pattern of subtypes expressed. We also examined these pancreases for the expression of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, IL-2, IL-4, and IL-6. We found no detectable expression of TNF-alpha or IL-2 in any pancreases, and the expression of the other cytokines was variable, with no pattern emerging from the comparison of the diabetic and nondiabetic individuals. We conclude that, of the cytokines examined, only IFN-alpha was significantly increased in the diabetic patients, a result that is consistent with the possibility that this cytokine is directly involved in the development of type I diabetes.
Diabetes 1995 Jun
PMID:Interferon expression in the pancreases of patients with type I diabetes. 754 May 71

Nitric oxide (NO) is believed to be an effector molecule that mediates interleukin (IL)-1 beta-induced destruction and dysfunction of pancreatic beta-cells. We have demonstrated that both exogenous NO and NO generated endogenously by IL-1 beta brought about apoptosis of isolated rat pancreatic islet cells as well as pancreatic beta-cell tumor-derived cell line HIT. This apoptosis was characterized by cleavage of DNA into nucleosomal fragments of 180-200 bp and morphologically by nuclear shrinkage, chromatic condensation, and apoptotic body formation. The IL-1 beta-induced internucleosomal DNA cleavage occurred in a time- and dose-dependent manner. Actinomycin D, cycloheximide, and nitric oxide synthase inhibitors inhibited the DNA cleavage, which was correlated with the amount of NO produced, indicating that NO produced by HIT cells themselves could mediate the apoptosis. Furthermore, in the presence of tumor necrosis factor (TNF)-alpha, large amounts of NO were produced by IL-1 beta and DNA cleavage occurred more noticeably, although TNF-alpha alone did not generate NO. Streptozotocin (STZ), a diabetogenic reagent containing a nitroso moiety, also released NO and induced internucleosomal DNA cleavage in HIT cells. These results suggest that NO-induced internucleosomal DNA cleavage is an important initial step in the destruction and dysfunction of pancreatic beta-cells induced by inflammatory stimulation or treatment with STZ.
Diabetes 1995 Jul
PMID:Apoptotic cell death triggered by nitric oxide in pancreatic beta-cells. 754 May 72

It has been postulated that cytokines may mediate the beta-cell destructive process causing insulin-dependent diabetes mellitus. The aim of this investigation was to study cytokine effects on pancreatic islet functions in vitro. For this purpose 5-7 days precultured (medium RPMI 1640 +/- 10% fetal calf serum) rat pancreatic islets were exposed for another 48 h to either culture medium alone or with addition of rat interferon-gamma (IFN-gamma; 1000 U/ml), or human tumor necrosis factor-alpha (TNF-alpha; 1000 U/ml) or a combination of the cytokines. After the culture period the islets were subjected to short-term experiments in the absence of cytokines. Neither the DNA nor the insulin content of the islets were affected by the cytokines alone or by the combination. The combination IFN-gamma + TNF-alpha caused a 5-fold increase in the medium nitrite accumulation, indicating induction of nitric oxide formation. It was found that IFN-gamma reduced medium insulin accumulation and basal insulin secretion at 1.7 mM glucose, without affecting the medium nitrite level. On the other hand, the islet glucose oxidation rate at 16.7 mM glucose and the insulin secretory response to 16.7 mM glucose was normal or even increased when examined after 48 h. TNF-alpha alone had no significant effects. In conclusion, a combination of the cytokines can induce nitric oxide formation and inhibition of insulin production in rat pancreatic islets. However, this effect appears not to be sustained. Moreover, IFN-gamma alone seems to induce changes not related to nitric oxide.
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PMID:Effects of prolonged exposure in vitro to interferon-gamma and tumour necrosis factor-alpha on nitric oxide and insulin production of rat pancreatic islets. 757 79

Peripheral blood mononuclear cells from patients with non-insulin-dependent diabetes mellitus (NIDDM) show reduced proliferative response to phytohemagglutinin (PHA) and other mitogens. This study was undertaken to determine whether this reduced lymphocyte proliferation is mediated by a decreased production of cytokine or decreased expression of interleukin-2 receptor (IL-2R). Mononuclear cells from NIDDM patients (n = 34) and healthy controls (n = 22) were cultured in RPMI-1640 media containing PHA, concanavalin-A and phorbol myristate acetate. NIDDM patients showed reduced [3H]thymidine uptake (57% of controls, P < 0.01), reduced percentage of IL-2R-positive cells (61% of controls, P < 0.02) and increased level of tumor necrosis factor (TNF)-alpha (200% of controls, P < 0.05). The percentage of complement receptor (CR) 3-positive monocytes from NIDDM patients was also decreased (72% of controls, P < 0.05). However, the production of IL-1 beta, IL-2 and interferon-gamma, the percentages of pan T cells (CD3), T helper cells (CD4), T suppressor cells (CD8), the ratio of CD4/CD8 and the expression of CR1 and Fc receptors for immunoglobulin G (Fc gamma RII and Fc gamma RIII) were not significantly different between NIDDM patients and healthy subjects. Human recombinant IL-2 was unable to restore the [3H]thymidine uptake by PHA-stimulated mononuclear cells from NIDDM patients. Elevation of glucose concentration up to 27.8 mmol/l in the culture medium did not suppress the [3H]thymidine uptake and IL-2R expression by activated lymphocytes from healthy subjects. The decreased expression of IL-2R on activated lymphocytes might be responsible for the insufficient lymphocyte proliferation in NIDDM patients. These findings suggest that decreased expression of CR3 on monocytes, decreased lymphocyte proliferation and decreased IL-2R expression despite a higher production of TNF-alpha may explain the impaired cell-mediated immunity seen in NIDDM patients.
Diabetes Res Clin Pract 1995 May
PMID:Decreased cell-mediated immunity in patients with non-insulin-dependent diabetes mellitus. 758 21

We have previously reported that the mRNA levels of extracellular matrix (ECM) components including alpha 1(I), alpha 1(III), and alpha 1(IV) collagen chains, laminin B1 and B2 chains, and growth factors including tumor necrosis factor (TNF)-alpha, platelet-derived growth factor (PDGF)-B chain, transforming growth factor (TGF)-beta, and basic fibroblast growth factor (FGF) all increase with age in diabetic glomeruli. The present study was designed to assess whether glomerular expression of these mRNAs in rat diabetic glomeruli is affected by a specific endothelin receptor A antagonist, FR139317. Diabetes was produced by streptozotocin injection, and animals were divided into four groups: untreated diabetic rats, FR139317-treated diabetic rats, control nondiabetic rats, and FR139317-treated control rats. FR139317 treatment was continued for 24 weeks. FR139317 attenuated the rise in creatinine clearance (P < 0.01) and reduced urinary protein excretion (P < 0.01) in diabetic rats, but did not affect blood pressure. FR139317 attenuated the increases in glomerular mRNA levels of alpha 1(I) (P < 0.01), alpha 1(III) (P < 0.01), and alpha 1(IV) (P < 0.01) collagen chains, laminin B1 (P < 0.01) and B2 (P < 0.01) chains, TNF-alpha (P < 0.01), PDGF-B (P < 0.01), TGF-beta (P < 0.001) and basic FGF (P < 0.01) in diabetic rats. However, FR139317 did not affect these mRNA levels in glomeruli of control rats. These findings suggest that FR139317 may be useful in the treatment of diabetic glomerulopathy by reducing mRNA levels of ECM components and growth factors.
Diabetes 1995 Aug
PMID:Effect of a specific endothelin receptor A antagonist on mRNA levels for extracellular matrix components and growth factors in diabetic glomeruli. 762 93

Markers of cell-mediated immune activation were studied in 32 Chinese patients with recent-onset insulin-dependent diabetes mellitus (IDDM) as compared with 12 patients with recent-onset non-insulin-dependent diabetes mellitus (NIDDM) and 34 normal subjects. Sera were assessed for soluble markers of T-cell activation (sCD4, sCD8, sIL-2R); the cytokines (IL-1 beta, TNF-alpha, IL-2, IL-6), and T-cell subsets were also determined. Only 1 of the 32 IDDM patients had increased sCD4 levels, 5 had increased sCD8, and 3 had increased sIL-2R. None of the sera from NIDDM patients and control subjects showed such increased levels of soluble markers. Three IDDM patients had detectable IL-1 beta and this weakly so (< 3.5 pg/ml). However, the other cytokine data and the frequency of activated T-cells, CD4+, CD8+ T-cell subsets and CD4:CD8 ratio showed no significant differences among the IDDM, NIDDM and normal subjects. Our data suggest that in addition to a low frequency of islet cell antibodies, Chinese patients with recent onset IDDM also showed a lack of serum markers of cellular activation.
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PMID:Soluble T-cell markers and serum cytokines in type I (insulin-dependent) diabetes mellitus. 764 84

To understand the role of TNF in the regulation of inflammation and the development of autoimmune diseases such as insulin-dependent diabetes mellitus, we produced transgenic mice in which the synthesis of murine TNF-alpha was directed by the rat insulin II promoter. The expression of the TNF-alpha transgene was restricted to the pancreas, in contrast to TNF-beta expression from the same promoter, in which the transgene was expressed in the pancreas, kidney, and skin. The expression of TNF-alpha in the pancreas of transgenic mice resulted in an overwhelming insulitis, composed of CD4+ and CD8+ T cells and B220+ B cells, considerably greater than that of TNF-beta transgenics. Moreover, in contrast to the predominant peri-insulitis observed in TNF-beta transgenic mice, the majority of the infiltrate in the TNF-alpha transgenic mice was within the islet itself. These unique patterns of infiltration were observed in the F1 progeny of crosses with C57BL/6 as well as NOD. Both TNF-alpha and TNF-beta transgenic mice show elevated expression of leukocyte adhesion molecules VCAM-1 and ICAM-1 in islet endothelia and increased expression of MHC class I on islet cells. This inflammation did not result in reduced insulin content of the islets, nor did it lead to diabetes. These data suggest that additional stimuli are necessary to initiate the process of islet destruction.
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PMID:Transgenic tumor necrosis factor (TNF)-alpha production in pancreatic islets leads to insulitis, not diabetes. Distinct patterns of inflammation in TNF-alpha and TNF-beta transgenic mice. 768 90

Tumor necrosis factor (TNF) bioactivity was assessed in culture media conditioned with uterine cells collected from control or diabetic rats on days 5 and 8 of pregnancy. On both days, diabetic uterine cells released significantly more biologically active TNF than did control cells, and this activity was significantly decreased by the addition of anti-TNF-alpha antibodies but not by the addition of normal IgG when WEHI 164 cells were used as a target. When uterine tissues from day 5 or day 8 pregnant diabetic rats were tested by Northern blot analysis, TNF-alpha mRNAs were twofold more abundant than in control samples, but the difference was not statistically significant (P = 0.086 and 0.100, respectively). Immunohistochemical analysis of diabetic day 5 uterine sections revealed that most of the TNF-alpha synthesis occurs in the epithelium lining the uterine lumen. Finally, the growth of day-5 embryos in culture medium conditioned with day-5 diabetic uterine cells was significantly reduced when compared with that of embryos in medium conditioned with control cells. Embryonic development was markedly improved when anti-TNF-alpha antibodies were added to the diabetic-cell conditioned medium. Our data support the hypothesis that TNF-alpha may be implicated in the developmental deficiencies observed in preimplantation embryos from pregnant diabetic rats.
Diabetes 1995 May
PMID:Possible role for TNF-alpha in early embryopathy associated with maternal diabetes in the rat. 772 11

Obesity is frequently associated with insulin resistance and abnormal glucose homeostasis. Recent studies in animal models have indicated that TNF-alpha plays an important role in mediating the insulin resistance of obesity through its overexpression in fat tissue. However, the mechanisms linking obesity to insulin resistance and diabetes in humans remain largely unknown. In this study we examined the expression pattern of TNF-alpha mRNA in adipose tissues from 18 control and 19 obese premenopausal women by Northern blot analysis. TNF-alpha protein concentrations in plasma and in conditioned medium of explanted adipose tissue were measured by ELISA. Furthermore, the effects of weight reduction by dietary treatment of obesity on the adipose expression of TNF-alpha mRNA were also analyzed in nine premenopausal obese women, before and after a controlled weight-reduction program. These studies demonstrated that obese individuals express 2.5-fold more TNF-alpha mRNA in fat tissue relative to the lean controls (P < 0.001). Similar increases were also observed in adipose production of TNF-alpha protein but circulating TNF-alpha levels were extremely low or undetectable. A strong positive correlation was observed between TNF-alpha mRNA expression levels in fat tissue and the level of hyperinsulinemia (P < 0.001), an indirect measure of insulin resistance. Finally, body weight reduction in obese subjects which resulted in improved insulin sensitivity was also associated with a decrease in TNF-alpha mRNA expression (45%, P < 0.001) in fat tissue. These results suggest a role for the abnormal regulation of this cytokine in the pathogenesis of obesity-related insulin resistance.
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PMID:Increased adipose tissue expression of tumor necrosis factor-alpha in human obesity and insulin resistance. 773 5


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