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

Biochemical assessments of micronutrient antioxidant status were done in 14 consecutive black patients with calcific chronic pancreatitis and 15 controls at Soweto, near Johannesburg in southern Africa. The patients showed subnormal levels of vitamin C in plasma; selenium, beta-carotene and alpha-tocopherol in serum; and inorganic sulphate (as an index of long-term sulphur amino acid intake) in urine (P < 0.001 for each): furthermore, among the patients ascorbate constituted a lower fraction of vitamin C (P < 0.002), indicating heightened oxidation of the bioactive form. By comparing the results in Sowetan controls with reference ranges from Manchester, UK, the markedly lower vitamin C and, hence, ascorbate levels in the Sowetans was underlined (P < 0.001) and their selenium levels were also lower (P < 0.001), but beta-carotene, alpha-tocopherol and inorganic sulphate levels were comparable. The very low bioavailability of ascorbate among Sowetan controls is reminiscent of our previous finding in outwardly healthy people at Madras in southern India: in both these areas chronic pancreatitis is currently endemic, has a propensity to pancreatic calculi and runs a virulent course towards premature death from diabetes, malnutrition or pancreatic cancer. Considering that low ascorbate levels are a feature in patients with chronic pancreatitis who develop pancreatic calculi at Manchester and that antioxidant supplements ameliorate painful symptoms, we suggest that poor antioxidant intake may predispose underprivileged tropical communities to the disease. If so, there could be an opportunity for prophylaxis through a daily tablet containing vitamin C, perhaps along with selenium at Soweto and beta-carotene at Madras.
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PMID:Micronutrient antioxidant status in black South Africans with chronic pancreatitis: opportunity for prophylaxis. 758 89

Evidence is accumulating that most of the degenerative diseases that afflict humanity have their origin in deleterious free radical reactions. These diseases include atherosclerosis, cancer, inflammatory joint disease, asthma, diabetes, senile dementia and degenerative eye disease. The process of biological ageing might also have a free radical basis. Most free radical damage to cells involves oxygen free radicals or, more generally, activated oxygen species (AOS) which include non-radical species such as singlet oxygen and hydrogen peroxide as well as free radicals. The AOS can damage genetic material, cause lipid peroxidation in cell membranes, and inactivate membrane-bound enzymes. Humans are well endowed with antioxidant defences against AOS; these antioxidants, or free radical scavengers, include ascorbic acid (vitamin C), alpha-tocopherol (vitamin E), beta-carotene, coenzyme Q10, enzymes such as catalase and superoxide dismutase, and trace elements including selenium and zinc. The eye is an organ with intense AOS activity, and it requires high levels of antioxidants to protect its unsaturated fatty acids. The human species is not genetically adapted to survive past middle age, and it appears that antioxidant supplementation of our diet is needed to ensure a more healthy elderly population.
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PMID:The role of free radicals in disease. 761 52

Ceruloplasmin (Cp) is an acute-phase-responsive oxidase enzyme. Prior reports suggest that Cp is increased in diabetes mellitus, perhaps reflecting greater oxidant stress. However, the situation in insulin-dependent diabetes mellitus (IDDM) per se remains unclear. Furthermore, vitamin C can interfere with one indirect assay for Cp, and vitamin C metabolism is altered in IDDM. We measured Cp levels by both a direct radial immunodiffusion (RID) assay and an indirect oxidase assay in 10 subjects with IDDM and 10 nondiabetics, both at baseline and after 30 days of vitamin C supplementation (100 or 600 mg daily, five subjects per group). Plasma copper level was measured independently also. Our data show that circulating levels of Cp are significantly increased in IDDM subjects as a group, and specifically that Cp is abnormally high in a subset of IDDM individuals. Vitamin C supplementation at either dose interfered with the oxidase assay for Cp in both groups, but vitamin C did not alter the RID assay. The observed increase in plasma copper suggests that circulating holo-Cp is increased. The finding of increased Cp in some individuals with IDDM supports the hypothesis of increased oxidant stress as a variable factor in the spectrum of chronic complications in diabetes. Measurements of Cp level by the oxidase assay must be considered unreliable for subjects taking vitamin C supplements of > or = 100 mg/d.
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PMID:Elevated plasma ceruloplasmin in insulin-dependent diabetes mellitus: evidence for increased oxidative stress as a variable complication. 763 57

alpha-Lipoic acid, which plays an essential role in mitochondrial dehydrogenase reactions, has recently gained considerable attention as an antioxidant. Lipoate, or its reduced form, dihydrolipoate, reacts with reactive oxygen species such as superoxide radicals, hydroxyl radicals, hypochlorous acid, peroxyl radicals, and singlet oxygen. It also protects membranes by interacting with vitamin C and glutathione, which may in turn recycle vitamin E. In addition to its antioxidant activities, dihydrolipoate may exert prooxidant actions through reduction of iron. alpha-Lipoic acid administration has been shown to be beneficial in a number of oxidative stress models such as ischemia-reperfusion injury, diabetes (both alpha-lipoic acid and dihydrolipoic acid exhibit hydrophobic binding to proteins such as albumin, which can prevent glycation reactions), cataract formation, HIV activation, neurodegeneration, and radiation injury. Furthermore, lipoate can function as a redox regulator of proteins such as myoglobin, prolactin, thioredoxin and NF-kappa B transcription factor. We review the properties of lipoate in terms of (1) reactions with reactive oxygen species; (2) interactions with other antioxidants; (3) beneficial effects in oxidative stress models or clinical conditions.
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PMID:alpha-Lipoic acid as a biological antioxidant. 764 94

Low ascorbate concentrations in diabetes may be secondary to inadequate dietary vitamin C intake or may relate to the varied metabolic roles of the vitamin. To determine whether inadequate dietary intake is a factor we calculated daily vitamin C intakes using both a vitamin C questionnaire and a 4-day food diary in a group of 30 patients with Type 2 diabetes (mean age 68.8 +/- 6.9 yr, 17M/13F) and in 30 community controls (mean age 68.0 +/- 5.5 yr, 12M/18F)). Measures of plasma glucose, serum fructosamine, and plasma ascorbic and dehydroascorbic acid were obtained from 20 subjects in each group. There was no significant difference in daily vitamin C intake between the two groups using both methods: food diary, 61.4 +/- 28.3 (patients) vs 69.5 +/- 33.4 (controls) mg; questionnaire, 54.0 +/- 28.9 (patients) vs 65.0 +/- 30.9 (controls) mg. Vitamin C intake derived from both methods was significantly correlated (p < 0.001). Plasma ascorbate (30.4 +/- 19.1 mumol l-1) and dehydroascorbate (27.6 +/- 6.4 mumol l-1) levels were significantly lower in patients vs in controls (68.8 +/- 36.0 and 31.8 +/- 4.8 mumol l-1, respectively), p < 0.0001 and p < 0.01. Plasma ascorbate levels were significantly correlated with vitamin C intake derived from the food diary (p < 0.01) and questionnaire (p < 0.01) methods in the diabetic group only. Low ascorbate levels in diabetes appears to be a consequence of the disease itself and not due to inadequate dietary intake of vitamin C. A short vitamin C questionnaire is a convenient and reliable estimate of vitamin C intake.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Low plasma ascorbate levels in patients with type 2 diabetes mellitus consuming adequate dietary vitamin C. 770 29

Three groups of 10 age- and sex-matched nondiabetic volunteers took 0, 750, or 1500 mg of vitamin C each day for 12 weeks. Glycohemoglobin (GHb) was measured by HPLC, electrophoresis, affinity chromatography, and immunoassay at baseline (-4 weeks and -1 day), during supplementation (6 weeks and 12 weeks), and after supplementation ended (6 and 12 weeks). Plasma vitamin C increased twofold during supplementation but, in contrast with the results of Davie et al. (Diabetes 1992; 41:167-73), there were no between-group differences in GHb, glucose, and fructosamine concentrations. Fructosamine may have increased with storage time. The net effects of vitamin C on absolute GHb at 12 weeks vs -1 day (and at 12 weeks vs 12 weeks after) in % GHb amounted to: HPLC -0.035 (-0.050); electrophoresis +0.005 (+0.035); affinity chromatography -0.070 (+0.015); and immunoassay -0.110 (+0.025). We conclude that supplementation of nondiabetics with 750 or 1500 mg of vitamin C daily for 12 weeks does not cause interference in GHb determinations by HPLC, electrophoresis, affinity chromatography, or immunoassay, and does not reduce in vivo Hb glycation.
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PMID:Vitamin C and glycohemoglobin. 772 50

As shown by mathematical analysis of a dependence of vitamin C excretion with urine on its content in blood as well as by plotting and mathematical interpretation of the variation curves exhibiting distribution of the ascorbic acid detected in blood plasma of persons additionally treated with vitamin C, the values 0.4-0.5 mg/dl of vitamin C (lower limit of normal values) may be recommended as a criterion of the vitamin normal consumption which corresponded to literature data. The value 0.7 mg/dl used in literature is the optimum content of vitamin C in blood. Excretion of vitamin C with urine, corresponding to lower limits of the vitamin consumption, constituted 0.4 mg/h in adults and 0.2 mg/h-in children of 5-14 years old. Metabolism of vitamin C in patients with diabetes mellitus was considerably distinct from that of healthy persons. As a criterion of normal vitamin C consumption in children of 9-13 years old impaired with diabetes mellitus, the content 1 mg/dl of vitamin C in blood plasma should be considered and its excretion with urine--more than 1.8 mg/h.
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PMID:[Refining criteria for supplying the body with vitamin C]. 777 Oct 95

A self-administered semiquantitative food frequency questionnaire including 75 food items and providing information on the habitual intake of 31 nutritional parameters, based on the intake of protein, fat, carbohydrate, fiber and 11 vitamins and minerals, was developed for use in epidemiologic research on chronic disease among the elderly, such as diabetes and cardiovascular disease. By means of detailed frequency and quantity questions, specifications of types of food, preparation methods and seasonal variation, the questionnaire was expected to be an improvement on existing instruments. The relative validity of the questionnaire was examined in 74 men and women, aged 50-75, by comparison with a modified dietary history. Systematic differences were absent or negligible for all nutrients, except vitamin C. Bias depending on the level of intake could be ruled out for all but seven nutrients. Pearson correlation coefficients for estimates from the questionnaire and dietary history were on average 0.71 (range: 0.65-0.78) and 0.66 (range: 0.36-0.81) for macronutrients, and vitamins and minerals, respectively. Classifying individual intake estimates into tertiles of the distribution for both methods, on average 62.4 and 54.7% of the intakes were categorized into the same tertile and 3.9 and 5.9% into the opposite tertile for macronutrients, vitamins and minerals, respectively. These results demonstrate an acceptable relative validity for this newly developed questionnaire, as compared to the dietary history method.
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PMID:A semiquantitative food frequency questionnaire for use in epidemiologic research among the elderly: validation by comparison with dietary history. 778 93

The specific activities of superoxide dismutase, catalase, and glutathione S-transferase (mu subtype) were significantly lower in the brains of mice with type II diabetes than in the brains of control mice. On the other hand, the specific activity of glutathione peroxidase was unaltered. The concentration of vitamin E, but not that of total glutathione and ascorbate, was increased in the brains of the type II diabetic mice. The relative amount of polyunsaturated fatty acids (as determined with soybean lipoxygenase) was increased in whole brains and crude synaptosomal membranes of the type II diabetic mice. Endogenous levels of thiobarbituric acid-positive material were decreased in both whole brain homogenates and crude synaptosomal membranes of the db/db mice. Susceptibility of lipids within whole brain homogenates and crude synaptosomal membranes of mice with type II diabetes to peroxidation with iron/ascorbate was also markedly decreased compared with that of controls. Vitamin E is known to quench lipid peroxidation. Therefore, decreased lipid peroxidation in the type II mouse brain may be due to increased vitamin E content.
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PMID:Antioxidant defense systems in the brains of type II diabetic mice. 779 Aug 73

Oxidative stress and protein glycation are closely related processes that may contribute to the development of complications in diabetes mellitus. Treatment with antioxidants could protect against these processes at a biochemical level, and we have therefore investigated the effects of ascorbate and desferrioxamine treatment in the streptozotocin diabetic rat. Diabetic animals were given ascorbate 1 g/l in drinking water or desferrioxamine 6 mg/kg/day by subcutaneous injection and were killed after 6 weeks. In diabetic animals, oxidative stress was increased as shown by increased levels of conjugated dienes (CD) in plasma and malondialdehyde (MDA) in plasma, erythrocyte membranes, and urine. In addition, there was depletion of the nutritional antioxidants ascorbate, alpha-tocopherol, and retinol. Insulin treatment returned all of these parameters to normal. Ascorbate supplementation or desferrioxamine treatment alone failed to reduce oxidative stress, but a combination of both interventions restored MDA, CD, and antioxidant vitamins to control values. Both ascorbate and desferrioxamine also reduced HbA1c and glycated albumin levels. Treatment with antioxidants can reduce both oxidative stress and protein glycation and may help to reduce the risk of developing diabetic complications. However, ascorbate can have both prooxidant and antioxidant effects in vivo, and its use in pharmacological doses should be approached with caution.
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PMID:The effects of desferrioxamine and ascorbate on oxidative stress in the streptozotocin diabetic rat. 779 90


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