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

Whole pancreas or beta-cell transplantation has opened the way for the treatment of advanced stage of diabetes mellitus. However, it is always limited by the scarcity of transplantation materials. The amniotic membrane is part of the fetal membrane and is composed of amniotic epithelium (HAE) and mesenchymal (HAM) cells that are derived from the inner cell mass in the blastocyst. Thus, HAE and HAM cells may have the potential to differentiate into various organs. The aim of our study was to assess the possibility of HAE cells differentiating into insulin-producing cells. In vitro, HAE cells stimulated with nicotinamide induced insulin mRNA in the culture cells. In vivo, HAE cells were capable of normalizing the blood glucose level of diabetic mice after several weeks of implantation into streptozotocin-induced diabetic mice. The distribution of human cells and human insulin secretion in mouse tissue studied by immunohistochemistry for anti-human-specific beta-2-microglobulin and anti-human-specific insulin shows the same location in mouse tissue. These studies suggest that HAE cells have the potential to differentiate into beta-cells in vivo, and hence that HAE cells have therapeutic potential for the treatment of type I diabetes mellitus.
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PMID:Human amnion-isolated cells normalize blood glucose in streptozotocin-induced diabetic mice. 1295 29

Type 1 diabetes is an immune-mediated disease characterized by a preclinical prodrome during which beta cell autoimmunity proceeds at a variable rate. Large geographic differences and a conspicuous increase in incidence, especially among young children since the 1950s, and the relatively low concordance in identical twins are factors that favor a critical role of environmental factors in the etiology of this disease. Only approximately 5% or fewer subjects with HLA-conferred genetic susceptibility to type 1 diabetes actually develop the clinical disease. Breastfeeding, nicotinamide, zinc, and vitamins C, D, and E have been reported as possibly protecting against type 1 diabetes, whereas N-nitroso compounds, cow milk, increased linear growth, and obesity may increase the risk. Thus far, only the significance of infant feeding, cow milk, and vitamin D have been studied in both case-control and cohort settings. The major shortcoming of most studies done so far is that only single dietary exposures have been assessed at single time points. Putative nutritional and other confounding factors have received little attention as have the limitations of the dietary methods used. There is little firm evidence of the significance of nutritional factors in the etiology of type 1 diabetes. The availability of good markers of preclinical type 1 diabetes and of genetic risk have decreased the sample sizes needed and made longitudinal cohort studies of the assessment of children's diets feasible.
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PMID:Nutritional risk predictors of beta cell autoimmunity and type 1 diabetes at a young age. 1466 64

Prevention of type 1 diabetes in high risk individuals presents with both positive and negative aspects. On one hand, the availability of reliable and convenient screening tools (antibodies) allows us to quantify the risk of diabetes in the short term. Large randomised studies have provided indisputable answers regarding the efficiency of selection of at risk patients. Unfortunately, both DPT-1 study (using insulin) and ENDIT trial (with nicotinamide) ruined the hopes raised from solid experimental data. These studies have also demonstrated the huge costs in terms of number of subjects, time for follow-up, and financial burden, requiring an international collaboration. Finally, only a small number of such studies can be conducted simultaneously. Progress and obstacles paving this research area must be explained to diabetic patients and their family. Current mitigated results should not drive us to give up screening campaigns. Rather, these results should prompt diabetes centers and families to participate in the selection of high risk individuals in order to explore new therapeutic options within future prevention trials.
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PMID:[Prevention of type 1 diabetes: what have we achieved? What should we say and propose next to families?]. 1470 96

Type 1 diabetes begins with the progressive autoimmune mediated destruction of the insulin-producing beta cells. When sufficient beta cell function is lost, the endocrine phase, characterized by insulin deficiency and hyperglycemia, supervenes. While a genetic predisposition to diabetes is an important precondition, most believe an environmental factor or factors serve as the trigger for initiating this process. In this paper we review trials designed to prevent or delay the clinical onset of diabetes. In these studies, high-risk individuals are identified by their genetic predisposition to diabetes, and/or by the presence of immune markers indicating activation of the autoimmune process directed against islet cells. The Deutsche Nicotinamide Intervention Study (DENIS) randomized 55 high-risk subjects to either nicotinamide or placebo and found no significant benefit. The European Nicotinamide Diabetes Intervention Trial (ENDIT) completed enrollment in May 1998. ENDIT screened over 40 000 relatives, randomizing 552 to either nicotinamide or placebo. Results are expected in May of 2003. Designed to test if avoidance of cow's milk in infancy will decrease the incidence of diabetes, the Trial to Reduce Type I Diabetes in the Genetically at Risk (TRIGR). High-risk infants are randomly assigned to different supplemental formulas in the first 6 months of life. Initial results suggest that removing cow's milk has a protective effect. The ongoing, NIH funded, multicenter Diabetes Prevention Trial-Type 1 (DPT-1) is testing two antigen-based (insulin) interventions in relatives at high risk for diabetes. Now in its sixth year, the DPT-1 study group has screened over 84,000 individuals. As of November 2000, 339 subjects have been randomized in the parenteral insulin study, completing the enrollment phase. Enrollment continues in the oral insulin study. Results of this trial are not yet available. Different epitopes of insulin and its analogs, monoclonal antibodies, and cytokine-based therapy, among others, have all been proposed as potential new interventional agents. While a great deal of effort will be required to test these approaches, the potential benefits of prevention justify these research efforts.
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PMID:Prevention of type 1a diabetes mellitus*. 1501 6

Type I diabetes mellitus is caused by an autoimmune destruction of the insulin-producing beta cells. The major obstacle in using transplantation for curing the disease is the limited source of insulin-producing cells. The isolation of human embryonic stem (hES) cells introduced a new prospect for obtaining a sufficient number of beta cells for transplantation. We present here a method for forming immature islet-like clusters of insulin-producing cells derived from hES cells. The protocol consisted of several steps. Embryoid bodies were first cultured and plated in insulin-transferrin-selenium-fibronectin medium, followed by medium supplemented with N2, B27, and basic fibroblast growth factor (bFGF). Next, the glucose concentration in the medium was lowered, bFGF was withdrawn, and nicotinamide was added. Dissociating the cells and growing them in suspension resulted in the formation of clusters which exhibited higher insulin secretion and had longer durability than cells grown as monolayers. Reverse transcription-polymerase chain reaction detected an enhanced expression of pancreatic genes in the differentiated cells. Immunofluorescence and in situ hybridization analyses revealed a high percentage of insulin-expressing cells in the clusters. In addition to insulin, most cells also coexpressed glucagon or somatostatin, indicating a similarity to immature pancreatic cells. Further improvement of this insulin-producing cell protocol may lead to the formation of an unlimited source of cells suitable for transplantation.
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PMID:Differentiation of human embryonic stem cells into insulin-producing clusters. 1515 4

For many years, the vast amount of data gathered from analysis of nonobese diabetic (NOD) and congenic NOD mice has eclipsed interest in the rat for the study of type 1 diabetes. The study of rat models has continued, however, and recently there has been a reanimation of interest for several reasons. First, genetic analysis of the rat has accelerated. Ian4L1, cblb, and Iddm4 are now known to play major roles in rat autoimmunity. Second, rats are amenable to study the interactions of genetics and environment that may be critical for disease expression in humans. Environmental perturbants that predictably enhance the expression of rat autoimmune diabetes include viral infection, toll-like receptor ligation, and depletion of regulatory T cell populations. Finally, data generated in the rat have correctly predicted the outcome of several human diabetes prevention trials, notably the failure of nicotinamide and low dose parenteral and oral insulin therapies.
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PMID:Rat models of type 1 diabetes: genetics, environment, and autoimmunity. 1522 75

Evidence from animal experiments and human observational studies suggests that some dietary micronutrients may protect against the development of type 1 diabetes. The most promising data so far have been obtained for a beneficial role of vitamin D. Beneficial effects of vitamin E (or other antioxidants) in diabetes development remain hypothetical. Despite plausible theoretical background evidence from animal experiments and supportive data from pilot studies, randomized, controlled trials using nicotinamide have not provided any evidence for a beneficial effect.
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PMID:Micronutrients and the risk of type 1 diabetes: vitamin D, vitamin E, and nicotinamide. 1549 67

The hallmark of immune-mediated type 1 diabetes is T cell-mediated destruction of the insulin-producing beta cells in the islets, which results from an imbalance between disease promoting factors and protective elements. The precise mechanisms of beta cell destruction leading to diabetes remain unclear. There are many molecules, including Fas ligand (FasL) and cytokines, such as IL-1, TNF-alpha and IFN-gamma that cause release of other cytokine-mediators that have potential to damage the beta cells. The beta cell-death appears to ultimately be caused by receptor (Fas/FasL)-mediated mechanisms and/or by secretion of cytotoxic molecules (e.g., granzymes, perforin). FasL-mediated beta cell damage might play a role in promoting insulitis and beta cell destruction in autoimmune diabetes in addition to toxic molecules, such as reactive oxygen species (superoxide, hydroxy radical, nitric oxide) or perforin. Furthermore, DNA damage in beta cells leads to poly (ADP-ribose) polymerase-activation which will increase NAD consumption and rapid depletion of NAD compromise ATP production in the cells. Nicotinamide inhibits poly (ADP-ribose) polymerase and reduces nitric oxide accumulation in the NOD pancreas and protect beta cells against radical-induced necrosis. Transgenic mice with beta cell specific overexpression of copper, zinc superoxide dismutase, or thioredoxin are resistant to autoimmune and STZ-induced diabetes. It is apparent that a number of different mechanisms of beta cell destruction are operative in type 1 diabetes. Blockage of multiple pathways, rather than a single pathway, of beta cell-death may, therefore be necessary to fully protect beta cells from destruction and thereby prevent type 1 diabetes.
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PMID:Prevention of type 1 diabetes: from the view point of beta cell damage. 1556 75

Clinical islet transplantation is an emerging procedure to cure type 1 diabetes. The graft is implanted by infusion into the liver through the portal vein. A major obstacle that still needs to be overcome is the requirement for islets from multiple donors to achieve insulin independence. An innate inflammatory reaction, the IBMIR, is elicited when islets are exposed to blood. The IBMIR has been described as a clotting reaction culminating in disruption of islet morphology and is a plausible cause for loss of tissue during the early post-transplant period. In this thesis, the underlying mechanisms of the IBMIR were characterized. The IBMIR was for the first time demonstrated in patients undergoing an islet transplant, and a number of clinically applicable strategies to limit this reaction were identified. The thrombin inhibitor melagatran completely blocked the IBMIR in an in vitro tubing blood loop system, indicating that thrombin is the driving force in the reaction. Interestingly, islets were shown to produce and secrete tissue factor (TF), the physiological trigger of coagulation. Inactivated FVIIa, a specific inhibitor of TF, successfully blocked initiation of the IBMIR. An alternative approach to limit the IBMIR was to pre-treat islets in culture prior to transplantation. Nicotinamide added to the culture medium effectively decreased the level of TF in human islets. Infiltration of immune cells, also a part of the IBMIR, was characterized in detail. The predominant cell types infiltrating the islets were neutrophilic granulocytes and, to a lesser degree, monocytes. Both cell types may exert direct cytotoxic effects, and the antigen-presenting monocytes may also be important for directing the specific immune system to the site of inflammation. These findings have provided new insight into the nature of the IBMIR and offer several new strategies to improve the outcome of clinical islet transplantation.
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PMID:The role of the innate immunity in islet transplantation. 1580 85

The pathogenesis of type 1 diabetes is multifactorial, involving genetic susceptibility, autoimmune mechanisms, and environmental factors. This article will focus on two main strategies for altering the underlying disease process in type 1 diabetes. The first strategy is to identify individuals at risk for the development of diabetes and to halt the immune process before it leads to overt clinical disease, Promising in vitro and animal studies with nicotinamide, parenteral insulin, and oral insulin led to large clinical prevention studies, such as the European Nicotinamide Diabetes Intervention Trial and the Diabetes Prevention Trial (DPT-1). These studies failed to show that nicotinamide and insulin prevented the disease in at risk relatives of patients with type 1 diabetes and left many questions unanswered. The second strategy focuses on intervention shortly after diagnosis in order to arrest the destruction of beta cells and to preserve residual beta-cell function as long as possible. Cyclosporin was an effective immunosuppressive but was rejected as a potential treatment for type 1 diabetes because of its renal toxicity. Recently, more attention has been focused on an anti-CD3 antibody, on DiaPep277, and on glutamic acid decarboxylase (GAD). Animal studies and small short-term human trials with these compounds have suggested that they may be effective interventions in patients recently diagnosed with type 1 diabetes.
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PMID:Therapeutic targets for the prevention of type 1 diabetes mellitus. 1608 57


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