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Query: UMLS:C0011854 (type 1 diabetes)
 20,749 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

T-cell-mediated loss of pancreatic beta-cells is the crucial event in the development of type 1 diabetes. The phenotypic characteristics of disease-associated T-cells in type 1 diabetes have not yet been defined. The negative results from two intervention trials (the Diabetes Prevention Trial-Type 1 Diabetes and the European Nicotinamide Diabetes Intervention Trial) illustrate the need for technologies to specifically monitor ongoing autoimmune reactions. We used fluorescence-activated cell sorter analysis to study surface marker expression on T-cell lines specific for two major type 1 diabetes autoantigens, GAD65 and proinsulin. We then applied this knowledge in a cross-sectional approach to delineate the phenotype of circulating memory T-cells. The autoreactive T-cells of patients could be distinguished from those of control subjects by their coexpression of CD25 and CD134. Autoantigen-specific T-cells that recognized multiple GAD65- and preproinsulin-derived peptides and coexpressed CD25(+)CD134(+) were confined to patients (n = 32) and pre-diabetic probands (n = 5). Autoantigen-reactive T-cells in control subjects (n = 21) were CD25(+)CD134(-) and recognized fewer autoantigen-derived peptides. Insulin therapy did not induce CD25(+)CD134(+) T-cells in type 2 diabetic patients. The coexpression of CD25 and the costimulatory molecule CD134 on memory T-cells provides a novel marker for type 1 diabetes-associated T-cell immunity. The CD134 costimulatory molecule may also provide a novel therapeutic target in type 1 diabetes.
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PMID:Coexpression of CD25 and OX40 (CD134) receptors delineates autoreactive T-cells in type 1 diabetes. 1638 Apr 76

Over the years, several clinical syndromes have been described in diabetes mellitus. Although world opinion has settled somewhat on the main two types, the debate continues as to how the 'formes frustes' syndromes fit in and what if any implications there are for the accepted aetiology of the disease. Type 1, insulin dependent diabetes mellitus, results from pancreatic inadequacy as a result of a variety of insults such as autoimmune attack, toxic damage, etc. Insulin administration is at the core of the therapeutic approach. Type 2, non insulin dependent diabetes mellitus, results from reduced responsiveness of the target tissues to insulin and as such, an insulin resistance syndrome is described. Lifestyle adjustment and oral hypoglycaemic agents are the mainstay of therapy. Over the years, however, insulin insufficiency will develop in most cases and insulin therapy required in order to achieve normoglycaemia. The aetiology of these main two types has been maintained to be distinct from each other and as such types 1 and 2 are described as two separate developmental conditions. Furthermore, the variant patterns, such as malnutrition related, drug induced, intermittent or phasic insulin requiring, gestational, temporary, stress related, etc., all present a challenge as to how they fit in aetiologically. The Unitarian Hypothesis, by presenting this overall cascade of biochemical and physiological interactions, brings a logic which embraces the points of entry of a variety of insults, all of which can lead to the clinical picture of hyperglycaemia and its attendant adverse outcomes. The hypothesis buttresses the belief that nature - the genetic predisposition which directs potential antibody development; and nurture - the environmental influences such as nutritional status (over- or under-), infective and toxic attack, can aggravate or initiate aspects of the cascade of reactions leading to hyperglycaemia. The causative agents functioning internally within the cascade are imputed to be free radicals, oxidizing molecular species and antibodies and the corollary to this overview concept would be that a situation that minimizes the genesis and accumulation of these three agents would minimize the development of diabetes mellitus. Currently the debate is rife about the use of free radical scavengers and antioxidants in the treatment and prevention of diabetes mellitus. The verdict is still out on this approach. Our research on rootcrops such as yams and cassava, staple foods in tropical countries, indicates the presence of cyanoglycosides such as linamarin, which on digestion yields cyanide radicals. These radicals are pancreatotoxic especially in the undernourished state. Dog models however, have shown that free radical scavengers such as riboflavin, Vitamin B(2), is protective against this toxic damage. Further, scientific investigations have clearly demonstrated the role of antibody attack and have been able to ward off the appearance of type 1 diabetes mellitus in susceptible individuals, by the early use of immunosuppressive therapy such as cyclosporin. Thus the Unitarian Hypothesis demonstrates how all types of clinical syndromes being described in diabetes mellitus are not necessarily variants of a specific illness but rather manifestations of a central process of membrane damage-->antibody response-->insulin inadequacy (quantitatively or qualitatively); and the future intervention in containing this disease may well lie in focusing on preservation of the integrity of the body's cell membranes.
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PMID:The Unitarian Hypothesis for the aetiology of diabetes mellitus. 1680 31

The antihyperglycemic actions of some aporphines and their derivatives in normal Wistar, streptozotocin (STZ)-induced diabetic (IDDM) and nicotinamide-STZ induced diabetic (NIDDM) rats were investigated in this study. These compounds included thaliporphine, glaucine, boldine, N-methyllaurotetanine, and predicentrine and the derivatives, N-[2-(2-methoxyphenoxy)ethyl]norglaucine and diacetyl- N-allylsecoboldine. Bolus intravenous injection of these compounds decreased the plasma glucose levels in a dose-dependent manner in both normal and diabetic rats. Among them, thaliporphine was found to have the most potent antihyperglycemic effect in both NIDDM and IDDM diabetic rats. It was found that thaliporphine could stimulate the release of insulin in both normal and diabetic rats, and a dose of 1 mg per kg thaliporphine could significantly attenuate the increase of plasma glucose induced by an intravenous glucose challenge test in normal rats. Similar treatment with thaliporphine significantly increased the skeletal muscle glycogen synthesis in both normal and diabetic rats. Hence, the hypoglycemic effect of thaliporphine in diabetic rats could be attributed to the stimulation of insulin release and the increase of glucose utilization.
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PMID:Antihyperglycemic effect of aporphines and their derivatives in normal and diabetic rats. 1692 83

We recently found that pancreatic acinar cells isolated from normal adult mouse can transdifferentiate into insulin-secreting cells in vitro. Using two different animal models of type 1 diabetes, we show here that insulin-secreting cells can also be generated from pancreatic acinar cells of rodents in the diabetic state with absolute insulin deficiency. When pancreatic acinar cells of streptozotocin-treated mice were cultured in suspension in the presence of epidermal growth factor and nicotinamide under low-serum condition, expressions of insulin genes gradually increased. In addition, expressions of other pancreatic hormones, including glucagon, somatostatin, and pancreatic polypeptide, were also induced. Analysis by the Cre/loxP-based direct cell lineage tracing system revealed that these newly made cells originated from amylase-expressing pancreatic acinar cells. Insulin secretion from the newly made cells was significantly stimulated by high glucose and other secretagogues. In addition, insulin-secreting cells were generated from pancreatic acinar cells of Komeda diabetes-prone rats, another animal model of type 1 diabetes. The present study demonstrates that insulin-secreting cells can be generated by transdifferentiation from pancreatic acinar cells of rodents in the diabetic state and further suggests that pancreatic acinar cells represent a potential source of autologous transplantable insulin-secreting cells for treatment of type 1 diabetes.
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PMID:Generation of insulin-secreting cells from pancreatic acinar cells of animal models of type 1 diabetes. 1692 84

The capacity for self-renewal and differentiation of human embryonic stem (ES) cells makes them a potential source for generation of pancreatic beta cells for treating type I diabetes mellitus. Here, we report a newly developed and effective method, carried out in a serum-free system, which induced human ES cells to differentiate into insulin-producing cells. Activin A was used in the initial stage to induce definitive endoderm differentiation from human ES cells, as detected by the expression of the definitive endoderm markers Sox17 and Brachyury. Further, all-trans retinoic acid (RA) was used to promote pancreatic differentiation, as indicated by the expression of the early pancreatic transcription factors pdx1 and hlxb9. After maturation in DMEM/F12 serum-free medium with bFGF and nicotinamide, the differentiated cells expressed islet specific markers such as C-peptide, insulin, glucagon and glut2. The percentage of C-peptide-positive cells exceeded 15%. The secretion of insulin and C-peptide by these cells corresponded to the variations in glucose levels. When transplanted into renal capsules of Streptozotocin (STZ)-treated nude mice, these differentiated human ES cells survived and maintained the expression of beta cell marker genes, including C-peptide, pdx1, glucokinase, nkx6.1, IAPP, pax6 and Tcf1. Thirty percent of the transplanted nude mice exhibited apparent restoration of stable euglycemia; and the corrected phenotype was sustained for more than six weeks. Our new method provides a promising in vitro differentiation model for studying the mechanisms of human pancreas development and illustrates the potential of using human ES cells for the treatment of type I diabetes mellitus.
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PMID:In vitro derivation of functional insulin-producing cells from human embryonic stem cells. 1742 93

Cells at the maternal-fetal interface express indoleamine 2,3 dioxygenase (IDO) to consume all local tryptophan for the express purpose of starving adjacent maternal T cells of this most limiting and essential amino acid. This stops local T cell proliferation to ultimately result in the most dramatic example of immune tolerance, acceptance of the fetus. By contrast, inhibition of IDO using 1-methyl-tryptophan causes a sudden catastrophic rejection of the mammalian fetus. Immunomodulatory factors including IFNgamma, TNFalpha, IL-1, and LPS use IDO induction in responsive antigen presenting cells (APCs) also to transmit tolerogenic signals to T cells. Thus it makes sense to consider IDO induction towards tolerance for autoimmune diseases in general. Approaches to cell specific therapeutic IDO induction with NAD precursor supplementation to prevent the collateral non-T cell pathogenesis due to chronic TNFalpha-IDO activated tryptophan depletion in autoimmune diseases are reviewed. Tryptophan is an essential amino acid most immediately because it is the only precursor for the endogenous biosynthesis of nicotinamide adenine dinucleotide (NAD). Both autoimmune disease and the NAD deficiency disease pellagra occur in women at greater than twice the frequency of occurrence in men. The importance of IDO dysregulation manifest as autoimmune pellagric dementia is genetically illustrated for Nasu-Hakola Disease (or PLOSL), which is caused by a mutation in the IDO antagonizing genes TYROBP/DAP12 or TREM2. Loss of function leads to psychotic symptoms rapidly progressing to presenile dementia likely due to unchecked increases in microglial IDO expression, which depletes neurons of tryptophan causing neurodegeneration. Administration of NAD precursors rescued entire mental hospitals of dementia patients literally overnight in the 1930's and NAD precursors should help Nasu-Hakola patients as well. NAD depletion mediated by peroxynitrate PARP1 activation is one of the few established mechanisms of necrosis. Chronic elevation of TNFalpha leading to necrotic events by NAD depletion in autoimmune disease likely occurs via combination of persistent IDO activation and iNOS-peroxynitrate activation of PARP1 both of which deplete NAD. Pharmacological doses of NAD precursors repeatedly provide dramatic therapeutic benefit for rheumatoid arthritis, type 1 diabetes, multiple sclerosis, colitis, other autoimmune diseases, and schizophrenia in either the clinic or animal models. Collectively these observations support the idea that autoimmune disease may in part be considered as localized pellagra manifesting symptoms particular to the inflamed target tissues. Thus pharmacological doses of NAD precursors (nicotinic acid/niacin, nicotinamide/niacinamide, or nicotinamide riboside) should be considered as potentially essential to the therapeutic success of any IDO-inducing regimen for treating autoimmune diseases. Distinct among the NAD precursors, nicotinic acid specifically activates the g-protein coupled receptor (GPCR) GPR109a to produce the IDO-inducing tolerogenic prostaglandins PGE(2) and PGD(2). Next, PGD(2) is converted to the anti-inflammatory prostaglandin, 15d-PGJ(2). These prostaglandins exert potent anti-inflammatory activities through endogenous signaling mechanisms involving the GPCRs EP2, EP4, and DP1 along with PPARgamma respectively. Nicotinamide prevents type 1 diabetes and ameliorates multiple sclerosis in animal models, while nothing is known about the therapeutic potential of nicotinamide riboside. Alternatively the direct targeting of the non-redox NAD-dependent proteins using resveratrol to activate SIRT1 or PJ34 in order to inhibit PARP1 and prevent autoimmune pathogenesis are also given consideration.
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PMID:Pharmacological targeting of IDO-mediated tolerance for treating autoimmune disease. 1743 Jan 13

Niacin (nicotinic acid and nicotinamide) is a vitamin used as a source of the NAD+ and NADP+ coenzymes required for many metabolic processes. Its low dietary levels induce the development of pellagra. Niacin has been used for decades in the treatment of patients with disturbed lipid and lipoprotein metabolism, this being the main cause of atherosclerotic changes in cardiovascular diseases. It is still the most efficacious drug in terms of its ability to increase HDL cholesterol content accompanied by a decrease in all atherogenic lipoproteins (VLDL, LDL, and L(a)) as well as fatty acids and triglycerides. Niacin also increases adiponectin level, which might result in additional atheroprotection. There are studies confirming the beneficial action of niacin against migraine and hyperphosphatemia associated with renal failure, ethanol-induced neurodegeneration, and loss of beta-cell function in type 1 diabetes. Moreover, it augments plasma tryptophan concentrations in HIV-infected patients and thyroid radiosensitivity to 131I. Inhibition of the invasion of hepatoma cells has also been proven. However, it is necessary to point out that the currently applied niacin preparations might exhibit such side effects as cutaneous flushing, gastrointestinal disturbances, and hepatotoxicity, particularly during treatment with sustained-release niacin preparations. The recent discovery of the G-protein-coupled receptor GPR109A, which mediates the antilipolytic effects induced by nicotinic acid in adipocytes as well as cutaneous vasodilation, allows the development of new agents interacting with this receptor. In view of these observations, niacin therapy must be accompanied by control of the choice of niacin preparation and its dose in order to eliminate or at least limit its side effects.
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PMID:[Niacin in therapy]. 1755 32

To prevent diabetic complications derived from enhanced glucose flux via the polyol pathway the development of aldose reductase inhibitors (ARIs) has been established as a promising therapeutic concept. Here, we study the binding process of inhibitors to aldose reductase (ALR2) with respect to changes of the protonation inventory upon complex formation. Knowledge of such processes is a prerequisite to factorize the binding free energy into enthalpic and entropic contributions on an absolute scale. Our isothermal titration calorimetry (ITC) measurements suggest a proton uptake upon complex formation with carboxylate-type inhibitors. As the protonation event will contribute strongly to the enthalpic signal recorded during ITC experiments, knowledge about the proton-accepting and releasing functional groups of the system is of utmost importance. However, this is intricate to retrieve, if, as in the present case, both, binding site and ligand possess several titratable groups. Here, we present pKa calculations complemented by mutagenesis and thermodynamic measurements suggesting a tyrosine residue located in the catalytic site (Tyr48) as a likely candidate to act as proton acceptor upon inhibitor binding, as it occurs deprotonated to a remarkable extent if only the cofactor NADP+ is bound. We furthermore provide evidence that the protonation state and binding thermodynamics depend strongly on the oxidation state of the cofactor;s nicotinamide moiety. Binding thermodynamics of IDD 388, IDD 393, tolrestat, sorbinil, and fidarestat are discussed in the context of substituent effects.
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PMID:Tracing changes in protonation: a prerequisite to factorize thermodynamic data of inhibitor binding to aldose reductase. 1790 6

This paper reviews worldwide efforts to interdict the type 1 diabetes (T1D) disease process, during the stage of evolution of the disease prior to the time of disease onset. The goal of intervention before disease onset is to arrest immune destruction and thus prevent or delay clinical disease. In this regard, there have been several large-scale multicenter randomized controlled clinical trials designed to prevent T1D. These have tested nicotinamide, parenteral insulin, oral insulin, nasal insulin, and the elimination of cow's milk from infant feeding.
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PMID:Update on worldwide efforts to prevent type 1 diabetes. 1912 Feb 93

Insulin dependent diabetes mellitus (IDDM) results from irreversible loss of beta cells (beta-cells) of the pancreas. A Streptozotocin (STZ)-induced diabetes in animal model mimics, in some aspects, recent onset IDDM. This study was conducted to investigate the effect of nicotinamide on experimentally-induced IDDM. Thirty Spraque Dawley rats were divided into 3 groups; a control group, a diabetic group which received an intraperitoneal (i.p.) injection of 55 mg/kg STZ and a nicotinamide group (1g/kg/day) which were dosed orally for 3 days followed by (i.p.) STZ (55 mg/kg) with the nicotinamide treatment continuing for an additional 14 days. Rats receiving STZ became diabetic after 2 weeks. This diabetic group showed hyperglycemia, and a very low level of C-peptide. Furthermore, pancreatic islets exhibited increased nitric oxide (NO) production together with an increased apoptotic index (as detected by TUNEL and electron microscopy). Nicotinamide treatment prevented STZ-induced diabetes, it also antagonized an increase in NO, and inhibited beta-cell apoptosis. Fasting blood glucose, serum insulin and serum C-peptide were all within the normal range in the nicotinamide group. The nicotinamide protection of beta-cells may be facilitated via inhibition of apoptosis and nitric oxide generation. It is suggested that nicotinamide might be considered an effective agent for the prevention and treatment of IDDM in prediabetic, and early stages, of IDDM.
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PMID:Effect of nicotinamide on experimental induced diabetes. 1927 54


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