Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0011854 (type 1 diabetes)
 20,749 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of nitric oxide (NO) and free radicals in the development of microvascular disease in type 1 diabetes remains unclear. We have measured NO and isoprostane (a stable marker of in vivo lipid peroxidation) production in 13 type 1 diabetic subjects with normal urinary albumin excretion and 13 healthy volunteers. Whole-body NO synthesis was quantified by measuring the urinary excretion of 15N-nitrate after the intravenous administration of L-[15N]2-arginine. The urinary excretion of the major urinary metabolite of 15-F2t-isoprostane (8-iso-prostaglandin-F2alpha), 2,3-dinor-5,6-dihydro-F2t-IsoP, was quantified as a marker of in vivo lipid peroxidation. Whole-body NO synthesis was significantly higher in diabetic subjects compared with control subjects (342 vs. 216 nmol 15N-nitrate/mmol creatinine [95% CI of the difference 45-207], P = 0.005). This increase was not explained by a difference in renal function between the 2 groups. There was no difference in 2,3-dinor-5,6-dihydro-F2t-IsoP excretion between diabetic subjects and control subjects (44.8+/-7.8 vs. 41.4+/-10.0 ng/mmol creatinine, mean +/- 95% CI). However, there was an inverse correlation between NO synthesis and free radical activity in subjects with diabetes (r = -0.62, P = 0.012) that was not observed in control subjects (r = 0.37, P = 0.107). We conclude that whole-body NO synthesis is higher in type 1 diabetic subjects with normal urinary albumin excretion than in control subjects. The inverse correlation between isoprostane production and NO synthesis in diabetic subjects is consistent with the hypothesis that NO is being inactivated by reactive oxygen species.
 ...
PMID:Nitric oxide synthesis and isoprostane production in subjects with type 1 diabetes and normal urinary albumin excretion. 1090 97

Secoisolariciresinol diglucoside (SDG) isolated from flaxseed has antioxidant activity and has been shown to prevent hypercholesterolemic atherosclerosis. An investigation was made of the effects of SDG on the development of diabetes in diabetic prone BioBreeding rats (BBdp rats), a model of human type I diabetes [insulin dependent diabetes mellitus (IDDM)] to determine if this type of diabetes is due to oxidative stress and if SDG can prevent the incidence of diabetes. The rats were divided into three groups: Group I, BioBreeding normal rats (BBn rats) (n = 10); group II, BBdp untreated (n = 11); and group III, BBdp treated with SDG 22 mg/kg body wt, orally) (n = 14). Oxidative stress was determined by measuring lipid peroxidation product malondialdehyde (MDA) an index of level of reactive oxygen species in blood and pancreas; and pancreatic chemiluminescence (Pancreatic-CL), a measure of antioxidant reserve. Incidence of diabetes was 72.7% in untreated and 21.4% in SDG-treated group as determined by glycosuria and hyperglycemia. SDG prevented the development of diabetes by approximately 71%. Development of diabetes was associated with an increase in serum and pancreatic MDA and a decrease in antioxidant reserve. Prevention in development of diabetes by SDG was associated with a decrease in serum and pancreatic-MDA and an increase in antioxidant reserve. These results suggest that IDDM is mediated through oxidative stress and that SDG prevents the development of diabetes.
 ...
PMID:Oxidative stress as a mechanism of diabetes in diabetic BB prone rats: effect of secoisolariciresinol diglucoside (SDG). 1094 5

In this study, our aim was to determine whether or not type 1 diabetes mellitus affects salivary sialic acid level and SOD activity. For this purpose, unstimulated saliva specimen was collected. Saliva sialic acid level and SOD activity were measured by the methods of Warren and Sun, respectively. We found significantly decline in salivary sialic acid level and SOD activity. The decrease of salivary sialic acid level in type 1 diabetes may be due to changes in the activities of the enzymes taking part of in the synthesis and catabolism of sialic acid. The main reason for the decrease of salivary SOD activity may be increased glycation of the enzyme and/or deleterious effect of increased free oxygen radicals by glycated proteins on SOD activity in diabetes. We conclude the decline both in sialic acid and SOD in saliva may be a possible factor leading to oral complications of diabetes mellitus.
 ...
PMID:Evaluation of salivary sialic acid level and Cu-Zn superoxide dismutase activity in type 1 diabetes mellitus. 1124 51

Pancreatic beta-cells are sensitive to a number of proapoptotic stimuli. Thus, apoptosis is an important part of the physiological neonatal remodeling of the endocrine pancreas, and a number of pathological stimuli involved in type 1 and type 2 diabetes have been shown to elicit beta-cell apoptosis. Factors of relevance to type 1 diabetes include proinflammatory cytokines, nitric oxide, and reactive oxygen species as well as Fas ligand. Recent findings that free fatty acids, glucose, sulfonylurea, and amylin cause beta-cell apoptosis in vitro suggest that programmed cell death may also be involved in the pathogenesis of type 2 diabetes. Furthermore, there is evidence favoring a convergence in signaling pathways toward common effectors of beta-cell apoptosis elicited by stimuli implicated in the pathogenesis of type 1 and type 2 diabetes. Therefore, recent studies involving the stimuli and signaling pathways of beta-cell apoptosis-in particular, mitogen- and stress-activated protein kinases-will be reviewed. It is concluded that immunological, inflammatory, and metabolic signals cause beta-cell apoptosis, and the possibility that these signals converge toward a common beta-cell death signaling pathway should be investigated further.
 ...
PMID:beta-cell apoptosis: stimuli and signaling. 1127 4

The aim of this study was to evaluate the cochlear micromechanics in type 1 diabetic patients and to compare these findings with diabetic microvascular complications (retinopathy and nephropathy). Cochlear activity was evaluated by recording 2f1-f2 DPOAE. DPOAEs were performed using an ILO92 Otodynamics Ltd Analyser. DPOAEs were measured in 42 normally hearing IDDM patients aged between 21 and 42 years, and 33 age-and sex-matched non-diabetic control subjects. IDDM patients were divided into two groups: 17 patients without microangiopathy and 25 with microangiopathy. Microangiopathy was evaluated with ophthalmoscopy and 24-hour albumin excretion rate into urine. Both groups (diabetic and control) had normal and undifferentiated results in tonal and impedance audiometry. The mean amplitudes of various DPOAEs were significantly reduced in the diabetic groups (with and without microangiopathy) compared with control subjects. No correlation was found between diabetic microvascular complications and DPOAE amplitudes reduction. Our results indicate the existence of an alteration in cochlear micromechanics in diabetic patients with microangiopathy as well as in patients without microangiopathy. The lack of significant correlation between the degree of microvascular complications in the retina or kidneys and DPOAEs amplitude reduction suggest that the impaired functional properties of the outer hair cells are probably caused by early metabolic complications in diabetes (among other things non-enzymatic glycation related to hyperactivity of free oxygen radicals) and not directly by diabetic microangiopathy.
 ...
PMID:Cochlear dysfunction and diabetic microangiopathy. 1131 68

The beta-cell toxin alloxan, which produces oxygen radicals, is a model substance in studies of type 1 diabetes. Recently, human beta-cells have been found to be relatively resistant to this toxin. To clarify species differences in alloxan diabetogenicity, and oxygen radical toxicity, mouse, rat, rabbit, dog, pig, human and guinea pig islets have been studied after alloxan exposure. Using a standardized in vivo model, where islets were transplanted to nude mice, the different islets were compared. The results demonstrated that mouse and rat islet grafts were morphologically disturbed by alloxan and ROS. Rabbit and dog islet graft morphology was reasonably intact; and human, porcine, and guinea pig islet grafts were all well preserved. Furthermore, ultrastructural signs of apoptosis and necrosis, disturbances in the insulin secretory pattern during and after an alloxan perifusion, and islet lysosomal enzyme activities were studied in vitro in islets from some species. Guinea pig beta-cells were affected by alloxan, but a regeneration process compensated for the observed apoptotic and necrotic cell death. Human islets did not show any signs of alloxan-induced damage in the different models studied. Finally, no correlation between high alloxan sensitivity and high lysosomal enzyme activity was found. Thus, the beta-cell lysosomes are hardly specific targets for alloxan.
 ...
PMID:Species differences in susceptibility of transplanted and cultured pancreatic islets to the beta-cell toxin alloxan. 1135 36

Insulin and exercise have been shown to activate glucose transport at least in part via different signaling pathways. However, it is unknown whether insulin resistance is associated with a defect in the ability of an acute bout of exercise to enhance muscle glucose uptake in vivo. We compared the abilities of insulin and isometric exercise to stimulate muscle blood flow and glucose uptake in 12 men with type 1 diabetes (age 24 +/- 1 years, BMI 23.0 +/- 0.4 kg/m(2)) and in 11 age- and weight-matched nondiabetic men (age 25 +/- 1 years, BMI 22.3 +/- 0.6 kg/m(2)) during euglycemic hyperinsulinemia (1 mU. kg(-1). min(-1) insulin infusion for 150 min). One-legged exercise was performed at an intensity of 10% of maximal isometric force for 105 min (range 45-150). Rates of muscle blood flow, oxygen consumption, and glucose uptake were quantitated simultaneously in both legs using [(15)O]water, [(15)O]oxygen, [(18)F]-2-fluoro-2-deoxy-D-glucose, and positron emission tomography. Resting rates of oxygen consumption were similar during hyperinsulinemia between the groups (2.4 +/- 0.3 vs. 2.0 +/- 0.5 ml. kg(-1) muscle. min(-1); normal subjects versus patients with type 1 diabetes, NS), and exercise increased oxygen consumption similarly in both groups (25.3 +/- 4.3 vs. 20.1 +/- 3.0 ml. kg(-1) muscle. min(-1), respectively, NS). Rates of insulin-stimulated muscle blood flow and the increments in muscle blood flow induced by exercise were also similar in normal subjects (129 +/- 14 ml. kg(-1). min(-1)) and in patients with type 1 diabetes (115 +/- 12 ml. kg(-1). min(-1)). The patients with type 1 diabetes exhibited resistance to both insulin stimulation of glucose uptake (34 +/- 6 vs. 76 +/- 9 micromol. kg(-1) muscle. min(-1), P < 0.001) and also to the exercise-induced increment in glucose uptake (82 +/- 15 vs. 162 +/- 29 micromol. kg(-1) muscle. min(-1), P < 0.05). We conclude that the ability of exercise to increase insulin-stimulated glucose uptake in vivo is blunted in patients with insulin-resistant type 1 diabetes compared with normal subjects. This could be caused by either separate or common defects in exercise- and insulin-stimulated pathways.
 ...
PMID:Resistance to exercise-induced increase in glucose uptake during hyperinsulinemia in insulin-resistant skeletal muscle of patients with type 1 diabetes. 1137 38

Pregnancy complicated by poor control of diabetes is associated with a higher risk of embryopathies, spontaneous abortions and perinatal mortality. A number of authors suggest an involvement of reactive oxygen species (ROS) in diabetic pregnancy. Determining lipid peroxidation products (LP), scavenging enzyme activities and the umbilical cord blood's acid-base balance may contribute to an adequate diagnosis of the neonate at birth. Nevertheless, such measurements seem to have limited value in practical clinical routine. The present study evaluates LP, antioxidant defence and acid-base status related to diabetic pregnancy. Twenty-eight women with type 1 diabetes (PGDM), 19 with gestational diabetes (GDM) and 13 control cases were investigated. An additional control group consisted of 15 healthy patients with negative diabetic history; all women underwent vaginal delivery. Immediately after delivery cord blood samples and placental tissue were collected for malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH) determination. Additionally, pH, pCO2, pO2 and base excess were measured in both vessels and compared to identify and exclude double venous samples. MDA levels in both cord blood and placental homogenates were significantly higher in both pregestational and gestational diabetic groups, but SOD activity was significantly diminished. Cord blood GSH was markedly elevated in PGDM and GDM. We have also shown significant differences in acid-base parameters in infants of PGDM group. Statistical analysis was performed using the Mann-Whitney U-test. These findings indicate an excessive oxidative stress in pregnancy complicated by diabetes mellitus. Evaluating LP products and scavenging enzyme activities may be valuable, sensitive indexes of fetal/neonatal threat in diabetic pregnancy in humans. Since oxidative stress is an important pathway for fetal injury, we believe that obtaining adequate measurements at the time of birth would contribute to clarifying the fetal/neonatal status in a medical and legal context and might be of value in altering therapy in newborn infants.
 ...
PMID:Lipid peroxidation, antioxidant defence and acid-base status in cord blood at birth: the influence of diabetes. 1138 27

The generation of an autoimmune response against islet beta-cells is central to the pathogenesis of type 1 diabetes mellitus, and this response is driven by the stimulation of autoreactive lymphocytes by components of the beta-cells themselves. Reactive oxygen species (ROS) have been implicated in the beta-cell destruction which leads to type 1 diabetes and may modify beta-cell components so as to enhance their immunogenicity. We investigated the effects of oxidation reactions catalysed by copper or iron on the major beta-cell autoantigen glutamic acid decarboxylase (GAD). Lysates of purified rat islets were exposed to copper or iron sulphate with or without hydrogen peroxide or ascorbic acid. Immunostaining showed that these treatments generated high molecular weight covalently linked aggregates containing GAD. These are not formed by intermolecular disulphide bonds between cysteine residues since they cannot be resolved into monomeric form when electrophoresed under extreme reducing conditions. There was no modification of insulin or pro-insulin by ROS. The same oxidative changes to GAD could be induced in viable islet cells treated with copper sulphate and hydrogen peroxide, and thus the modifications are not an artefact of the catalysed oxidation of cell-free lysates. Sera from patients with type 1 diabetes and stiffman syndrome containing GAD antibodies reacted predominantly with the highest molecular weight modified protein band of GAD: normal human sera did not precipitate GAD. Thus, oxidatively modified aggregates of GAD react with serum antibodies of type 1 diabetes patients and some SMS patients: this is consistent with oxidative modifications of autoantigens being relevant to the pathogenesis of type 1 diabetes.
 ...
PMID:Islet glutamic acid decarboxylase modified by reactive oxygen species is recognized by antibodies from patients with type 1 diabetes mellitus. 1170 67

To become insulin independent, patients with type 1 diabetes mellitus require transplantation of at least two donor pancreata because of massive beta-cell loss in the early post-transplantation period. Many studies describing the introduction of new immunosuppressive protocols have shown that this loss is due to not only immunological events but also nonimmunological factors. To test to what extent hypoxia may contribute to early graft loss, we analyzed the occurrence of apoptotic events and the expression of hypoxia-inducible factor 1 (HIF-1), a heterodimeric transcription factor consisting of an oxygen-dependent alpha subunit and a constitutive beta subunit. Histological analysis of human and rat islets revealed nuclear pyknosis as early as 6 h after hypoxic exposure (1% O2). Moreover, immunoreactivity to activated caspase-3 was observed in the core region of isolated human islets. Of note, both of these markers of apoptosis topographically overlap with HIF-1alpha immunoreactivity. HIF-1alpha mRNA was detected in islets from human and rat as well as in several murine beta-cell lines. When exposed to hypoxia, mouse insulinoma cells (MIN6) had an increased HIF-1alpha protein level, whereas its mRNA level did not alter. In conclusion, our data provide convincing evidence that reduced oxygenation is an important cause of beta-cell loss and suggest that HIF-1alpha protein level is an indicator for hypoxic regions undergoing apoptotic cell death. These observations suggest that gene expression under the control of HIF-1 represents a potential therapeutic tool for improving engraftment of transplanted islets.
 ...
PMID:Apoptosis in hypoxic human pancreatic islets correlates with HIF-1alpha expression. 1192 16


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>