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

Oxidative stress has been related to the development of diabetic neuropathy. Experimental diabetes (alloxan injection of mice) promotes early biochemical changes in peripheral nervous tissue, e.g. decrease in Na,K-ATPase activity and glutathione (GSH) peroxidase (GSHPx) activity. The former decrease can be reverted by inhibiting protein kinase C (PKC), since it has been reported that PKC is activated in these experimental conditions. Here we present data demonstrating that the inhibition of PKC, as early as 4 days after alloxan administration, is not able to return to normal values GSHPx activity in sciatic nerve of diabetes mice. Thus, it would fit with our previous proposal of the possible glycation of this protein as an early event in experimental diabetes, and apparently rules out the control of GSHPx activity by PKC in this tissue.
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PMID:Experimental diabetic neuropathy: role of oxidative stress and mechanisms involved. 969 7

Specific antagonists of platelet-activating factor (PAF) receptors inhibit platelet aggregation and thromboxane synthesis. These two processes have been implicated in the course of diabetic retinopathy. We assessed the effect of a specific PAF receptor antagonist, WEB 2086-BS (3-(4-(2-chlorophenyl)-9-methyl-6H-thieno(3,2-f) (1,2,4 triazolo-(4,3-a(1,4)-diazepine-2-yl)-1-(4-morpholinyl)-1-propanone) on retinal vascularity in a model of experimental streptozocin-induced diabetes in rats. Rats were divided into five experimental groups (10 animals/group): group I, non-diabetic group II, untreated diabetic group III, diabetic given 1 mg/kg per day of WEB 2086-BS (p.o.) group IV, diabetic given 5 mg/kg per day (p.o.) and group V, diabetic given 10 mg/kg per day (p.o.). After 3-month treatment, platelet aggregometry, platelet synthesis of thromboxane B2, aortic production of 6-keto-prostaglandin F1alpha, platelet and vascular lipid peroxidation, and percentage of the retinal area occupied by horseradish peroxidase-labeled vessels were measured. Untreated diabetic rats showed an increase in platelet reactivity, reduced 6-keto-prostaglandin F1alpha production, increased thromboxane B2 and lipid peroxides, and a decrease in the percentage of retinal area occupied by horseradish peroxidase-labeled vessels. WEB 2086-BS produced a decrease in platelet aggregation induced by collagen in whole blood, in thromboxane B2 synthesis and lipid peroxide production, and an increase in the percentage of retinal area occupied by horseradish peroxidase-labeled vessels (13.9+/-1.1% in group II and 9.9+/-0.8% in group V). There was a statistically significant linear correlation (Y= -0.72 + 137X, r2 = 0.7247, P < 0.0007) between thromboxane B2 values and the percentages of retinal area occupied by horseradish peroxidase-labeled vessels in the groups of animals treated with WEB 2086-BS.
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PMID:Effect of WEB 2086-BS, an antagonist of platelet-activating factor receptors, on retinal vascularity in diabetic rats. 984 70

Results of the initial clinical evaluation in 20 human subjects of a subcutaneously implanted microsensor-based amperometrically glycemia-monitoring system, carried out between April 1994 and June 1995, are reported. The system was based on the electrical connection ("wiring") of the reaction centers of glucose oxidase to a gold electrode and on elimination of the chemicals that interfere with glucose monitoring through their horseradish peroxidase-catalyzed oxidation by internally generated hydrogen peroxide. The sensor was finer than a 29-gauge needle and had no leachable components. Because of its high selectivity for glucose, the sensor output was virtually nil at zero glucose level. This enables prompt "one-point" in vivo calibration of the sensor with a single blood glucose sample. Microsensors were subcutaneously implanted in ten nondiabetic and ten insulin-dependent diabetes mellitus (IDDM) volunteers. All subjects underwent standard meal tests and intravenous glucose-tolerance tests (IVGTT) in addition to hourly plasma glucose measurements. The sensor signals were continuously recorded, and the glucose concentration estimates were derived by calibrating the sensor using a single blood sample (one-point calibration). Regression analysis revealed that the sensor-estimated glucose concentrations were linearly related to the plasma glucose concentrations (r2 = 0.75) over a wide glucose concentration range (2-28 mmol/L) (sensor estimate = plasma 0.96 + 0.26 mmol/L). The difference between the estimated and actual glucose concentration was -0.13+/-0.23 mmol/L [mean +/-95% confidence interval (CI), n = 546], and 95% of the estimates fell in clinically acceptable zones of the Clarke error grid. The sensing delay time was 10.4+/-2.3 min as measured by the IVGTT. The subjects reported no discomfort associated with wearing the sensors.
J Diabetes Complications
PMID:Initial evaluation of a 290-microm diameter subcutaneous glucose sensor: glucose monitoring with a biocompatible, flexible-wire, enzyme-based amperometric microsensor in diabetic and nondiabetic humans. 987 61

Chronic hyperglycemia in diabetes determines the overproduction of free radicals, and evidence is increasing that these contribute to the development of diabetic complications. It has recently been reported that dehydroepiandrosterone possesses antioxidant properties; this study evaluates whether, administered daily for three weeks per os, it may provide antioxidant protection in tissues of rats with streptozotocin-induced diabetes. Lipid peroxidation was evaluated on liver, brain and kidney homogenates from diabetic animals, measuring both steady-state concentrations of thiobarbituric acid reactive substances and fluorescent chromolipids. Hyperglycemic rats had higher thiobarbituric acid reactive substances formation and fluorescent chromolipids levels than controls. Dehydroepiandrosterone-treatment (4 mg/day for 3 weeks) protected tissues against lipid peroxidation: liver, kidney and brain homogenates from dehydroepiandrosterone-treated animals showed a significant decrease of both thiobarbituric acid reactive substances and fluorescent chromolipids formation. The effect of dehydroepiandrosterone on the cellular antioxidant defenses was also investigated, as impaired antioxidant enzyme activities were considered proof of oxygen-dependent toxicity. In kidney and liver homogenates, dehydroepiandrosterone treatment restored to near-control values the cytosolic level of reduced glutathione, as well as the enzymatic activities of superoxide-dismutase, glutathione-peroxidase, catalase. In the brain, only an increase of catalase activity was evident (p < .05), which reverted with dehydroepiandrosterone treatment. The results demonstrate that DHEA treatment clearly reduces oxidative stress products in the tissues of streptozotocin-treated rats.
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PMID:Dehydroepiandrosterone protects tissues of streptozotocin-treated rats against oxidative stress. 1040 10

Previous studies have shown a high prevalence of gastric parietal cell antibodies (PCA) in type 1 diabetes, which can be accompanied by (sub)clinical autoimmune gastric disease. This study aimed to determine the grade of associated autoimmunity and to assess the pattern of prevalence of PCA by gender, age, duration of disease, age at onset of diabetes, and human leukocyte antigen (HLA) type in an adult type 1 diabetic population. Furthermore, to examine the clinical significance of being PCA positive, manifestations of gastric autoimmune disease were studied in PCA-positive and PCA-negative patients. The population studied consisted of 497 type 1 diabetics (men/women, 252/245; mean age, 40.8 +/- 12.1 yr; mean duration of disease, 16.4 +/- 10.4 yr; mean age at onset, 26.9 +/- 13.5 yr; mean hemoglobin A1c, 8.1 +/- 1.6%). Associated autoantibodies were present in 39% and PCA were present in 20.9% of the subjects, particularly in older patients. Gender, duration, and age at onset of diabetes did not influence the appearance of PCA. Antithyroid peroxidase antibodies (aTPO) were more frequent in PCA-positive patients than in those without PCA (33.6% vs. 22.4%; P = 0.025), suggesting an association between gastric and thyroid autoimmunity. We could demonstrate an association between PCA and the HLA DR5 haplotype (P = 0.001) as well, but not with HLA DR3 and/or DR4. In the PCA-positive group, iron deficiency anemia was detected in 15.4%, and pernicious anemia was found in 10.5% of subjects. These autoimmune gastric manifestations were significantly more prevalent in PCA-positive diabetics than in PCA-negative subjects, in whom the percentages were 6.9% and 0.5%, respectively (P = 0.01 and P < 0.0001). PCA were prevalent in 84.6% of patients with pernicious anemia. A gastroscopic and anatomopathological examination performed in a subgroup of 30 patients with gastric symptoms revealed atrophic gastritis in 13 of 14 PCA-positive patients and in 9 of 16 PCA-negative subjects (P = 0.04). PCA were present in 59.1% of patients with atrophic gastritis. In conclusion, a high prevalence of parietal cell antibodies and associated autoimmune gastric disease is present in PCA-positive type 1 diabetics, recommending its screening. Early detection of PCA and iron deficiency anemia, pernicious anemia, and atrophic gastritis and the subsequent care could reduce the morbidity of type 1 diabetes.
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PMID:High prevalence of manifestations of gastric autoimmunity in parietal cell antibody-positive type 1 (insulin-dependent) diabetic patients. The Belgian Diabetes Registry. 1056 50

A peroxidase from yeast that reduces H2O2 with the use of electrons provided by thioredoxin (Trx) together with homologs from a wide variety of species constitute the peroxiredoxin (Prx) family of proteins. Twelve mammalian Prx members have been previously identified in association with various cellular functions apparently unrelated to peroxidase activity. These mammalian proteins have now been divided into three distinct types, Prx I, II, and III, on the basis of their deduced amino acid sequences and immunological reactivity. With the use of recombinant proteins, Prx I, II, and III have now been shown to possess peroxidase activity and to rely on Trx as a source of reducing equivalents. None of the three proteins exhibited peroxidase activity in the presence of glutaredoxin. All three enzymes showed similar kinetic properties: the Vmax was 6-13 micromol/min per mg at 37 degrees C, the Km for Trx was 3-6 microM, and the Km for H2O2 was < 20 microM. Immunoblot analysis of various rat tissues and cultured cells indicated that most cell types contain the three Prx isoforms, the sum of which amounts to approximately 1-10 microg per milligram of soluble protein. Prx I and II are cytosolic proteins, whereas Prx IlI is localized in mitochondria. These results suggest that, together with glutathione peroxidase and catalase, Prx enzymes likely play an important role in eliminating peroxides generated during metabolism as well as during stimulation of cell surface receptors.
Diabetes Res Clin Pract 1999 Sep
PMID:Characterization of three isoforms of mammalian peroxiredoxin that reduce peroxides in the presence of thioredoxin. 1058 61

Children with insulin-dependent diabetes mellitus have a lower salivary flow rate, pH and buffer capacity, but a higher glucose content and peroxidase, IgA, magnesium and calcium concentration, in comparison with healthy children. Nevertheless the incidence of caries is lower than normal in diabetic children with good metabolic control. Periodontal disease usually starts at puberty as mild gingivitis with bleeding and gingival recession, and it may develop into severe periodontitis, especially in children with poor control of diabetes. Microangiopathy, impaired immune response, different bacterial microflora and collagen metabolism are involved in the pathogenesis of diabetic periodontal disease. The gingival flora is mostly composed of Gram-negative, anaerobic bacteria, while collagen has a lower solubility and is atrophic and inadequate to support the occlusion forces. For these reasons, prevention of periodontitis is important in diabetic children; they should receive oral hygiene instruction and visit a dentist at least twice a year.
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PMID:Oral health in children and adolescents with IDDM--a review. 1070 31

Children with insulin-dependent diabetes mellitus have a lower salivary flow rate, pH and buffer capacity, but a higher glucose content and peroxidase, IgA, magnesium and calcium concentration, in comparison with healthy children. Nevertheless the incidence of caries is lower than normal in diabetic children with good metabolic control. Periodontal disease usually starts at puberty as mild gingivitis with bleeding and gingival recession, and it may develop into severe periodontitis, especially in children with poor control of diabetes. Microangiopathy, impaired immune response, different bacterial microflora and collagen metabolism are involved in the pathogenesis of diabetic periodontal disease. The gingival flora is mostly composed of Gram-negative, anaerobic bacteria, while collagen has a lower solubility and is atrophic and inadequate to support the occlusion forces. For these reasons, prevention of periodontitis is important in diabetic children; they should receive oral hygiene instruction and visit a dentist at least twice a year.
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PMID:Oral health in children and adolescents with IDDM--a review. 1085 89

The relationship between glycaemic metabolic control and intracellular concentration of reduced glutathione (GSH) and related enzymes GSH-peroxidase (GSH-Px), GSH-reductase (GSH-Red), GSH-transferase (GSH-Tr), glucose-6-P-dehydrogenase (G6PDH), and thioltransferase (TT) in patients with insulin-dependent diabetes mellitus (IDDM) is controversial. Choosing platelets as cell model (as commonly done in previous studies), the aim of this study was to relate the platelet content of GSH and related enzymes to glycaemic metabolic control, expressed as glycated haemoglobin (HbA1c), as well as to presence of retinopathy and nephropathy in 114 IDDM patients. As compared to controls, both GSH and GSH-Red (geometric means (95% CI)) were significantly increased in platelets of diabetic patients: 3.3 (0.7-9.6) vs. 2.4 (0.8-7.6) mmol 10(-9) platelets; P=0.01 for GSH, and 30.6 (14.7-61.6) vs. 22.2 (8.7-52.2) mU 10(-9) platelets, P=0.0002 for GSH-Red, and TT activity was marginally decreased in the IDDM group (P=0.06). While no clear relationship was present between GSH-related enzymes and HbA1c, a trend was present toward a non-linear relation between HbA1c and GSH, being significantly related by a parabolic curve (P=0.002). As compared to patients with normoalbuminuria (n=88), diabetic patients with increased urinary albumin excretion rate (n=26) had a significant decrease in platelet TT concentration (3.2 (0.9-6.7) vs. 5.1 (1.9-18.7) mU 10(-9) platelets; P=0.0002), whereas retinopathy was not associated to modifications in GSH or in the enzymatic pattern. In summary: (a) platelet GSH and GSH-Red are increased in IDDM, while other enzymes are unmodified; (b) GSH seems to be related to metabolic control according to non-linear parabolic curve; (c) presence of increased albuminuria is associated to a selective decrease in platelet TT content.
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PMID:Relationship between metabolic glycaemic control and platelet content of glutathione and its related enzymes, in insulin-dependent diabetes mellitus. 1090 Feb 97

Sequential changes in androgen receptor (AR) distribution were investigated in rat ovarian follicles during their physiological development. Mature female Wistar rats, exhibiting a regular 4-day oestrous cycle, were killed in succession on the day of oestrus, metoestrus, dioestrus, and pro-oestrus. Excised ovaries were submitted to immunohistochemical procedure in which polyclonal androgen receptor antibody, avidin-biotin-peroxidase complex, and DAB were used. Strong AR immunostaining was located predominantly in the nuclei of the granulosa layer of preantral and very early antral follicles, present in the ovaries at all stages of the oestrous cycle. At early oestrus a decline in AR was noted in the mural granulosa cells of presumably recruited early antral follicles. The decline involved the area of appearing pseudostratification. During metoestrus and dioestrus AR decline proceeded towards the antrum, but the antral regions connected with COC by strings of granulosa cells or lying in close proximity to COC were always strongly AR-positive. It was only on the day of pro-oestrus that AR was confined to COCs and a few antral cells bordering the antrum. These findings indicate that during the oestrous cycle AR decline starts in the mural granulosa cells of oestrous antral follicles beginning to differentiate and is completed at pro-oestrus, but even before ovulation it does not extend to COC. The persistence of AR immunostaining in the latter region suggests that androgens can play here a paracrine role especially before ovulation. Atretic follicles showed a different pattern of AR distribution, dependent on their stage of development and the advancement of this process.
Exp Clin Endocrinol Diabetes 2000
PMID:Changes in distribution of androgen receptor during maturation of rat ovarian follicles. 1092 21


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