ascorbic-acid and Albuminuria

The present study was designed to assess the effect of magnesium plus zinc, vitamins C plus E, and a combination of these micronutrients on nephropathy indexes in type 2 diabetic patients.. In a randomized, double-blind, placebo-controlled clinical trial, 69 type 2 diabetic patients were randomly divided into four groups, each group receiving one of the following daily supplement for 3 months: group M (n = 16), 200 mg Mg and 30 mg Zn; group V (n = 18), 200 mg vitamin C and 100 IU vitamin E; group MV (n = 17), minerals plus vitamins; and group P (n = 18), placebo. Urinary albumin excretion and N-acetyl-beta-d-glucosaminidase activity (NAG) in urine were determined at the beginning and at the end of the trial. Treatment effects were analyzed by general linear modeling.. Results indicate that after 3 months of supplementation, levels of urinary albumin excretion decreased in the V and MV groups (P = 0.034 and P = 0.005, respectively). Urinary NAG activity did not significantly change in any treatment groups. Levels of systolic, diastolic, and mean blood pressure significantly decreased in the MV group (P = 0.008, P = 0.017, and P = 0.009, respectively). Also, combination of vitamin and mineral supplementation had significant effects in decreasing fasting serum glucose (P = 0.035) and malondialdehyde concentrations (P = 0.004) and in increasing HDL cholesterol and apolipoprotein A1 levels (P = 0.019). There was no significant change in the levels of these parameters in the other three groups.. In conclusion, the results of the present study provide evidence for the effects of vitamins C and E and also combination of magnesium, zinc, and vitamins C and E supplementation on improvement of glomerular but not tubular renal function in type 2 diabetic patients.

Topics: Adult; Aged; Albuminuria; Ascorbic Acid; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Drug Therapy, Combination; Female; Humans; Kidney Glomerulus; Kidney Tubules; Magnesium; Male; Middle Aged; Treatment Outcome; Vitamin E; Vitamins; Zinc

Our aim was to investigate mechanisms of inflammation-induced endothelial dysfunction in humans.. Endothelial function in twenty-one healthy human volunteers was measured using forearm venous plethysmography before and 8 h after administration of typhoid vaccination to generate an inflammatory response. Basal and stimulated endothelial nitric oxide (NO) bioavailability was assessed by measurement of the responses to intra-arterial N(G)-monomethyl-l-arginine (l-NMMA) and bradykinin, respectively. The effects of supplementation with l-arginine or ascorbic acid were assessed to probe the effects of substrate deficiency and oxidative stress, respectively. Systemic effects were determined by measuring cytokine response, total anti-oxidant status (TAOS) and urinary protein excretion.. Vaccination induced a cytokine response, a fall in total anti-oxidant status and increased urinary albumin excretion (UAE). There was a reduction in the response to bradykinin (BK, P<0.005) and l-NMMA (P<0.0001) with no effect on the response to glyceryl trinitrate (GTN) and norepinephrine (NE). Following vaccination blood flow response to BK (but not GTN) was partially returned to pre-vaccine levels by infusion of ascorbic acid (P=0.01). Supplementation with l-arginine had no effect.. Inflammation causes widespread endothelial dysfunction, reduces vascular NO bioavailability and increases oxidative stress. These actions are partially reversible with local anti-oxidants. These findings suggest a role for reactive oxygen species in inflammation-induced endothelial dysfunction.

Topics: Adult; Albuminuria; Analysis of Variance; Arginine; Ascorbic Acid; Biological Availability; Bradykinin; Dose-Response Relationship, Drug; Endothelium, Vascular; Female; Forearm; Humans; Male; Nitric Oxide; Nitroglycerin; Norepinephrine; omega-N-Methylarginine; Oxidative Stress; Plethysmography; Regional Blood Flow; Statistics, Nonparametric; Typhoid-Paratyphoid Vaccines; Vasoconstrictor Agents; Vasodilator Agents

Renal failure after lower torso ischemia is a serious problem, partly caused by hypotension and indirect reperfusion injury. This injury is partly due to the formation of oxygen free radicals by activated neutrophils. This injury results in albuminuria and renal function impairment. There are indications that free radical damage in indirect reperfusion injury can be diminished by administering extra antioxidants before and during reperfusion.. In this prospective randomised study we have looked at the influence of a multi-antioxidant supplementation on renal function in patients undergoing an elective open infrarenal abdominal aneurysm repair. The patients received either standard treatment (n=22) or standard treatment with additional antioxidants perioperatively (Allopurinol, vitamin E and C, N-acetylcysteine and mannitol). For renal function we have looked at the albumin/creatinine ratio in urine and 24 hr creatinine clearance.. Despite significantly increased serum total antioxidant capacity, the group receiving extra antioxidants showed no decrease in the albumin/creatinine ratio in urine. There was however a significantly higher creatinine clearance in this group at day 2.. The results indicate that the diminished renal function after infrarenal aneurysm repair may be influenced by antioxidant therapy.

Topics: Acetylcysteine; Aged; Albuminuria; Allopurinol; Antioxidants; Aortic Aneurysm, Abdominal; Ascorbic Acid; Female; Humans; Kidney Function Tests; Male; Mannitol; Prospective Studies; Renal Insufficiency; Reperfusion Injury; Vitamin E

The hypoglycemic drug, troglitazone (TGZ) has antioxidant activity. Superoxide dismutase (SOD) removes superoxide produced by cells. We measured the response of SOD-like activity (deltaSOD) to ascorbic acid (AA) or TGZ using electron spin resonance at various glucose concentrations in polymorphonuclear leukocytes from 18 type 2 diabetic patients and 18 healthy controls. In control and diabetic subjects, ASOD in response to AA was dose-dependent (maximal effect at 100 ng/ml). Maximal response occurred 2 min after AA addition (50 ng/ml). In cells from diabetic patients, ASOD with 25 ng/ml AA was significantly less than for healthy controls. The deltaSOD with AA changed little at glucose concentration from 0 to 200 mg/dl. In patient and control cells, higher glucose concentrations (400 to 800 mg/dl) reduced ASOD with AA. Response patterns with TGZ resembled those with AA. deltaSOD with AA correlated positively with glycosylated hemoglobin A1c.. The present data suggest that an amerioration of blood glucose on high levels in diabetic patients plays an important role in an antioxidant efficacy of TGZ and AA on leukocytes in patients.

Topics: Aged; Albuminuria; Antioxidants; Ascorbic Acid; Chromans; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Diabetic Retinopathy; Dose-Response Relationship, Drug; Electron Spin Resonance Spectroscopy; Female; Glucose; Glycated Hemoglobin; Humans; Hypoglycemic Agents; Leukocytes; Male; Middle Aged; Superoxide Dismutase; Thiazoles; Thiazolidinediones; Troglitazone

Elevated levels of urinary albumin excretion rate (AER) predict high risk for progressing to end-stage renal disease. In streptozotocin-induced diabetes, supplementation with vitamin C or E reduces albuminuria and glomerular hypertrophy. We tested the hypothesis that supplementation of both vitamin C and E in pharmacological doses lowers AER in Type 2 diabetic patients with persistent micro/macroalbuminuria.. Thirty Type 2 diabetic patients with AER 30-300 mg/24 h were included in a double-blind randomised, cross-over trial. Patients received vitamin C (1250 mg) and vitamin E (680 IU) per day or matching placebo for 4 weeks with a 3-week wash-out period between treatment periods in random order.. Combined treatment with vitamin C and E reduced AER by 19% (95% CI 6-34%) (p = 0.04), geometric mean 197 mg/24 h (95% CI 114-341 mg/24 h) vs. 243 mg/24 h (146-404 mg/24 h). No changes were seen in serum creatinine, haemoglobin A1C or blood pressure. Fasting plasma concentrations of vitamin C and E increased in all patients during active treatment (mean vitamin C 79.4 micromol/L (SD 27.8) vs. 41.9 micromol/L (18.4) and vitamin E 47.0 micromol/L (19.8) vs. 29.5 micromol/L (15.3), P < 0.000001). Except for two patients that started additional blood pressure lowering treatment during the run-in period, no changes in medication, food and exercise habits or in the number of smokers occurred during the study.. Short-term treatment with vitamin C and E in pharmacological doses lowers AER in Type 2 diabetic patients with micro/macroalbuminuria. Further long-term, large-scale studies of this albuminuria reducing treatment modality are warranted.

Topics: Albuminuria; alpha-Tocopherol; Ascorbic Acid; Cross-Over Studies; Diabetes Mellitus, Type 2; Double-Blind Method; Drug Therapy, Combination; Fasting; Female; Glycated Hemoglobin; Humans; Male; Middle Aged; Placebos; Vitamin E

The important role of ascorbic acid (AA) as an anti-oxidant is particularly relevant in diabetes mellitus where plasma concentrations of AA are reduced. This study was conducted to evaluate the effects of treatment with AA or an aldose reductase inhibitor, tolrestat, on AA metabolism and urinary albumin excretion in diabetes. Blood and urine samples were collected at 0, 3, 6, 9, and 12 months from 20 diabetic subjects who were randomized into two groups to receive either oral AA 500 mg twice daily or placebo. Systolic and diastolic blood pressures, HbA1c, plasma lipids, urinary albumin, and total glycosaminoglycan excretion were measured at all time points, and heparan sulphate (glycosaminoglycan) was measured at 0 and 12 months. The same parameters, as well as urinary AA excretion, were determined at 0 and 3 months for 16 diabetes subjects receiving 200 mg tolrestat/day. AA treatment increased plasma AA (ANOVA, F ratio = 12.1, p = 0.004) and reduced albumin excretion rate (AER) after 9 months (ANOVA, F ratio = 3.2, p = 0.03), but did not change the other parameters measured. Tolrestat lowered plasma AA (Wilcoxon's signed-rank test, p < 0.05), but did not change AER or the other parameters measured. The ability of AA treatment to decrease AER may be related to changes in extracellular matrix or improvement in oxidative defence mechanism. Unlike the rat model of diabetes, inhibition of aldose reductase did not normalize plasma AA or AER in humans. In fact, tolrestat reduced the plasma AA concentration, a phenomenon which may be due to increased utilization of AA. Dietary supplementation of AA in diabetic subjects may have long-term benefits in attenuating the progression of diabetic complications.

Topics: Administration, Oral; Adult; Aged; Albuminuria; Aldehyde Reductase; Ascorbic Acid; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Double-Blind Method; Drug Administration Schedule; Female; Glycosaminoglycans; Humans; Male; Middle Aged; Naphthalenes; Placebos; Proteoglycans; Time Factors

Epidemiological studies show that 5-40 % of type 2 diabetes (T2DM) patients have diabetic nephropathy, and oxidative stress is one of several underlying mechanisms. We investigated associations between oxidative stress markers and severity of diabetic nephropathy.. Fifty-nine T2DM patients from the endocrinology outpatient department were included, and their levels of oxidative stress markers were measured. Three groups were determined by their urine albumin-to-creatinine ratio (UACR): group A (UACR < 30 mg/g, n = 22); group B (30 ≤ UACR < 300 mg/g, n = 22); and group C (UACR ≥ 300 mg/g, n = 15).. Vitamin C levels correlated negatively and moderately with serum creatinine (γ = -0.459, p < 0.001), urine albumin (γ. Our results identified several oxidative stress markers that may be clinically important in diabetic nephropathy. Studies with larger sample sizes should be undertaken to confirm these findings.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Albuminuria; Antioxidants; Ascorbic Acid; Biomarkers; Creatinine; Deoxyguanosine; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Female; Glomerular Filtration Rate; Humans; Male; Middle Aged; Oxidative Stress; Predictive Value of Tests; Prognosis; Prospective Studies; Severity of Illness Index

Oxidative stress has been suggested to play a role as a common mediator of apoptosis and kidney damage in diabetes. However, it is uncertain whether the apoptosis occurs in the kidney during the course of diabetes. We investigated the occurrence of apoptosis in the diabetic rat kidney, the role of oxidative stress and the effect of an antioxidant on apoptosis in the diabetic rat kidney.. Otsuka-Long-Evans-Tokushima-Fatty rats, an animal model for type 2 diabetes, were randomized into a non-treated diabetic (n=8) and a vitamin C-treated group (n=8). Long-Evans Tokushima Otsuka rats (n=8) were used as a control.. Apoptosis was present in the epithelial cells of the proximal tubules in diabetic rats. The number of apoptotic cells, albuminuria, proteinuria, glomerular and tubulointerstitial sclerosis, and renal malondialdehyde were significantly decreased in vitamin C-treated diabetic rats when compared to the untreated diabetic rats. The decreased slit pore density (number of slit pores per underlying glomerular basement membrane length) as assessed by electron microscopy was also significantly restored by treatment with vitamin C without significantly affecting plasma glucose in diabetic rats.. By blocking these pathophysiologic processes, a blockade of oxidative stress by vitamin C might become a useful adjunct to albuminuria and renal sclerosis in diabetic nephropathy.

Topics: Albuminuria; Animals; Antioxidants; Apoptosis; Ascorbic Acid; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Kidney; Male; Oxidative Stress; Rats; Rats, Inbred OLETF; Sclerosis

Microalbuminuria may increase the risk for cardiovascular disease. Increased oxidative stress, which may be important in the pathophysiological process of cardiovascular disease, occurs frequently in people with microalbuminuria and could depress their antioxidant concentrations, which then could contribute to end-organ damage associated with microalbuminuria.. We examined associations between microalbuminuria and circulating concentrations of vitamins A, C, and E and carotenoids in 9,575 US adults aged 20 years or older who participated in the Third National Health and Nutrition Examination Survey (1988 to 1994).. After adjustment for age, sex, race or ethnicity, education, smoking status, cotinine concentration, physical activity, alcohol use, fruit and vegetable intake, vitamin or mineral use during the past 24 hours, body mass index, systolic blood pressure, and total cholesterol, triglyceride, glucose, insulin, and C-reactive protein concentrations, concentrations of beta-cryptoxanthin (odds ratio for quartile of highest concentration compared with quartile of lowest concentration, 0.56; 95% confidence interval, 0.38 to 0.82), lutein/zeaxanthin (odds ratio, 0.59; 95% confidence interval, 0.37 to 0.94), lycopene (odds ratio, 0.64; 95% confidence interval, 0.46 to 0.89), and total carotenoids (odds ratio, 0.54; 95% confidence interval, 0.38 to 0.75) were associated inversely with microalbuminuria. Vitamin C, vitamin E, and selenium concentrations were not significantly associated with microalbuminuria.. People with microalbuminuria may have reduced concentrations of selected antioxidants. Additional research is needed to examine the relationships between microalbuminuria and antioxidant status, mechanisms for depletion of antioxidants, and possible benefits from increased intake of antioxidants through dietary change or the use of supplements in people with microalbuminuria.

Topics: Adult; Albuminuria; Antioxidants; Ascorbic Acid; Carotenoids; Female; Humans; Male; Middle Aged; United States; Vitamin A; Vitamin E

to assess the relations among plasma levels of von Willebrand factor (vWf), microalbuminuria and markers of oxidative stress in patients with type 2 diabetes mellitus.. We studied 10 healthy subjects without microalbuminuria or history of coronary artery disease (CAD) and 30 patients with type 2 diabetes mellitus who were classified into three groups, each including 10 patients of matched age and sex; group 1: patients without microalbuminuria or history of CAD; group 2: patients with microalbuminuria and no history of CAD, and group 3: patients with microalbuminuria and history of CAD. All subjects underwent laboratory measurements of vWf, albumin excretion rate (AER), malondialdehyde, vitamin C, reduced glutathione and C peptide.. vWf was elevated in patients with type 2 diabetes mellitus compared with control subjects. However, levels were higher in patients with than without microalbuminuria and in patients with than without a history of CAD (96+/-12, 124+/-7, 149+/-9, 175+/-7 in the control subjects and the diabetic patients' groups respectively). There was a positive correlation between vWf and AER, MDA and C- peptide (r=0.91, 0.98, 0.96, p<0.0001) and a negative correlation between vWf and both vitamin C and reduced glutathione (r=-0.59 and -0.62 respectively, p<0.001).. vWf levels are elevated in patients with type 2 diabetes mellitus, particularly in the presence of microalbuminuria and history of CAD. vWf levels are associated with markers of increased oxidative stress and therefore reflect the severity of biochemical abnormalities, which contribute to diabetic vascular disease.

Topics: Albuminuria; Ascorbic Acid; C-Peptide; Diabetes Mellitus, Type 2; Female; Glutathione; Humans; Male; Malondialdehyde; Oxidative Stress; Platelet Adhesiveness; von Willebrand Factor

The aim of this study was to analyze the effect of vitamins C and E on malondialdehyde (MDA) content and activities of key antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) as well as glomerular basement membrane (GBM) thickness in streptozotocin-induced diabetic kidney in rats. Wistar male rats were divided into following groups (12 rats each): the control, diabetic rats, diabetic rats whose drinking water was supplemented with vitamin C in a dose of 1.0 g/l or diet was supplemented with 200 mg of vitamin E/100 g fodder. Body weight, blood glucose and HbA1C levels and 24-hour urinary albumin excretion (UAE) were studied every week (0-12 weeks). After 6 and 12 weeks, MDA content and activities of SOD, CAT and GSH-Px were measured in the kidney homogenate supernatants. Electron micrographs of glomeruli were scanned and morphometric investigations were performed by means of computer image analysis system to compare GBM thickness. The blood glucose and HbA1C concentrations and UAE in diabetic rats were significantly higher than in the control group. An increase in the MDA level and decrease in the SOD, CAT and GSH-Px activities in the kidney of diabetic rats were observed after 6 and 12 weeks of experiment. Administration of vitamins C and E did not affect body weight, blood glucose and HbA1C levels. Both vitamin C and vitamin E decreased lipid peroxidation and augmented the activities of antioxidant enzymes studied in the kidneys of diabetic rats as well as reduced UAE, decreased kidney weight and GBM thickness. The results indicate the potential utility of antioxidant vitamins in the protection against the development of diabetic nephropathy.

Topics: Albuminuria; Animals; Antioxidants; Ascorbic Acid; Basement Membrane; Blood Glucose; Body Weight; Catalase; Diabetes Mellitus, Experimental; Dietary Supplements; Glomerular Mesangium; Glutathione Peroxidase; Glycated Hemoglobin; Male; Malondialdehyde; Organ Size; Rats; Rats, Wistar; Superoxide Dismutase; Time Factors; Vitamin E

In diabetic nephropathy and hypertension, a major cause of mortality is from cardiovascular disease. Since low levels of antioxidants such as vitamin C have been associated with such complications, we have examined the uptake mechanisms for ascorbic acid (AA) and dehydroascorbic acid (DHA) in lymphoblasts from normal control subjects (CON), normoalbuminuric insulin-dependent diabetic (IDDM) patients (DCON), patients with IDDM and nephropathy (DN) and hypertensive patients (HT) using mass assays of uptake and measuring AA using high-performance liquid chromatography. Precautions were taken to prevent oxidation of AA and to take into account the instability of DHA in buffers. DHA uptake was the major mechanism in all four groups of subjects, and the Vmax (maximal uptake rate) was significantly lower in the DN cells (24.7 +/- 1.0 nmol [95% confidence intervals CI 22.5, 26.3] 10(6) cells(-1) h(-1)) compared to CON and DCON cells (33.9 +/- 2.1 [95% CI 29.4, 38.4] and 37.0 +/- 2.2 [95% CI 32.2, 41.8] nmol 10(6) cells(-1) h(-1), respectively, p < 0.001 for both). DHA Vmax was also lower in the HT group (23.2 +/- 1.1 [95% CI 20.7, 25.7] nmol 10(6) cells(-1) h(-1)) compared to the CON group (p < 0.001). There were no significant differences in the Km or passive membrane permeability for DHA or the AA uptake. DHA uptake showed a negative correlation to systolic blood pressure (r(s) = -0.49, p < 0.001). These findings suggest that impaired DHA uptake may be one component of the phenotype expressed by DN cells that may persist in culture. Impaired DHA uptake in vivo, especially in the presence of hyperglycaemia, leads to impaired regeneration of AA and depletion of anti-oxidant defences, exposing such individuals to increased risk of cardiovascular disease.

Topics: Adult; Aged; Albuminuria; Ascorbic Acid; Biological Transport; Cells, Cultured; Dehydroascorbic Acid; Diabetes Mellitus, Type 1; Diabetic Nephropathies; Female; Humans; Hypertension; Kinetics; Male; Middle Aged; Models, Biological; Reference Values

Pathogenesis of diabetes-related microvascular complications involving oxidative damage by free radicals has been demonstrated. Free radical generation has been shown to derive largely from iron. Our objectives, therefore, were to determine if there is an increased incidence and/or an accelerated course of nephropathy in patients with diabetes, secondary to transfusional hemochromatosis, and to examine whether free radical activity contributes to the development of this complication.. We evaluated nine patients with homozygous beta-thalassemia, complicated by clinically overt diabetes, for diabetic nephropathy over a 7-year period. Lipid peroxidation was quantified by measuring the presence of 20 saturated and unsaturated aldehydes, and results were compared with five normotensive type 1 diabetic patients without iron overload.. Nephropathy developed in five of nine patients (55%) after a mean duration of overt diabetes of 3.6 +/- 2.0 years. Three patients showed evidence of progressive microalbuminuria over a 7-year period (24.7-46.2, 52.2-430.1, and 17.7-54.3 micrograms/min, respectively). Two patients with borderline microalbuminuria (19.9 and 14.5 micrograms/min, respectively) demonstrated stable albumin excretion rates over the follow-up period. Total aldehyde concentration was significantly higher in beta-thalassemia diabetic patients, compared with nonthalassemic diabetic control subjects (8,106 +/- 1,280 vs. 4,594 +/- 247 nmol/l; P < 0.0001). The three patients with progressive microalbuminuria demonstrated significantly higher total aldehyde concentration, compared with the other beta-thalassemia diabetic patients with stable albumin excretion (9,428 +/- 337 vs. 7,445 +/- 1,003 nmol/l; P < 0.01). Serum vitamin E concentrations were significantly lower in beta-thalassemia patients with diabetes, compared with diabetic patients without iron overload (12.1 +/- 6.0 vs. 25.9 +/- 11.4 mumol/l; P = 0.02). Serum vitamin C concentrations did not differ between the two groups. Multiple regression analysis demonstrated total aldehyde concentration to be the most significant predictor for the development of microalbuminuria (P = 0.01), followed by the duration of diabetes (P = 0.02) and glycemic control (P = 0.02).. Early development and an accelerated course of diabetic nephropathy in iron-loaded patients with beta-thalassemia are observed. These findings may be attributed to high oxidative stress in these patients, which is secondary to iron-derived free radicals and to the patients' diminished antioxidant reserves.

Topics: Adult; Albuminuria; Aldehydes; Antioxidants; Ascorbic Acid; beta-Thalassemia; Blood Glucose; Blood Pressure; Diabetes Complications; Diabetes Mellitus; Diabetic Nephropathies; Fructosamine; Homozygote; Humans; Iron; Kidney Function Tests; Lipid Peroxidation; Oxidative Stress; Retrospective Studies; Transfusion Reaction; Vitamin E

Oxidant stress and a reduction in antioxidant status, including reduced plasma and tissue ascorbic acid content, occur in diabetic patients and experimental models of diabetes. In this study, the effects of treatment of streptozotocin diabetic rats for 2 mo with vitamin C (10 g/kg body wt/d) or dietary vitamin E (200 mg/kg body wt/d) in the drinking water on urinary albumin excretion, glomerular transforming growth factor (TGF)-beta content, and glomerular size were examined. Treatment of diabetic rats with vitamin C or E had no effect on blood glucose levels compared with that in untreated diabetics (453 +/- 28 g/dl +/- SEM). Body weight, BP, and creatinine clearance rates were not significantly different among the study groups. Kidney weight was significantly higher in all of the diabetic groups compared with age-matched control rats. Treatment with vitamin C, but not vitamin E, significantly reduced kidney weight compared with that in untreated diabetic rats. Immunohistochemical staining for TGF-beta was 2.5-fold higher in glomeruli of cortical sections from untreated diabetic rats versus control rats. Treatment with vitamin C or E prevented the increase in glomerular TGF-beta immunoreactivity. Glomerular volume was also significantly increased (twofold) in kidneys of untreated diabetic rats compared with control rats, as assessed by light microscopy. Treatment with vitamin C prevented and treatment with vitamin E reduced the increase in glomerular volume. Treatment with vitamin C also prevented the sevenfold increase in albumin clearance otherwise seen in untreated diabetic rats. By contrast, treatment with vitamin E had no effect on albumin clearance despite reductions in glomerular size and TGF-beta. Renal cortical vitamin E and plasma, but not renal cortical vitamin C, were reduced in diabetic rats versus control rats. Supplementation of diabetic rats with vitamin C markedly increased plasma and renal cortical vitamin C content to values greater than those in control rats. Supplementation with vitamin E increased renal cortical vitamin E content by 50% compared with values in control rats and also increased plasma and renal cortical vitamin C. These results support the potential utility of antioxidant treatment for the prevention of renal injury in diabetes.

Topics: Albuminuria; Animals; Ascorbic Acid; Diabetes Mellitus, Experimental; Female; Kidney Cortex; Kidney Glomerulus; Rats; Rats, Sprague-Dawley; Transforming Growth Factor beta; Vitamin E

The relationship between serum ascorbic acid (AA) and diabetic macroangiopathy was studied. Fifty-six patients with noninsulin-dependent diabetes mellitus were examined, together with 20 healthy controls matched for age against the diabetes patients. Aortic pulse wave velocity (PWV) was taken as an index of the severity of atherosclerosis. The level of serum AA in diabetic patients was significantly lower than that of the controls. Among the diabetic groups, those with elevated PWV levels by age demonstrated a significant drop in AA. No significant differences were seen in the level of serum dehydroascorbic acid (DHAA) between patients and controls, nor were there any significant differences among patient groups. The concentration of serum AA was inversely related to the risk factors of atherosclerosis, such as body mass index, Apo B/ Apo A-I ratio, thiobarbituric acid-reactive substances (TBARS), and microalbumin in urine. It was inferred from these findings that the depletion of serum AA was apparent in diabetics with advanced atherosclerosis.

Topics: Adult; Aged; Albuminuria; Aorta; Apolipoprotein A-I; Apolipoproteins B; Arteriosclerosis; Ascorbic Acid; Body Mass Index; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Female; Humans; Male; Middle Aged; Rheology; Thiobarbituric Acid Reactive Substances

Serum ascorbic acid (AA) is reduced in diabetic patients. Aim of this study was 1) to verify whether such a decrease might be due to an altered urinary excretion of AA, and 2) whether this latter was modified in presence of early diabetic nephropathy with microalbuminuria (albumin excretion rate [AER] > 20 micrograms/min) in a group of 21 patients affected by insulin-dependent (type 1) diabetes mellitus (IDDM) as compared with 13 healthy controls matched for sex, age, dietary AA intake, and creatinine clearance per 1.73 m2 (CCl). Mean serum AA (+/- SD) was lower in diabetics (40.3 +/- 14 microM/l) than in controls (85.1 +/- 23.5 microM/l; p = 0.0001) and there was no difference between serum AA of patients with or without microalbuminuria. Urinary excretion of AA to creatinine x 100 (UAA/Cr) was higher in micro- (n = 6; 4.6 +/- 1.7) as compared to normoalbuminurics (n = 15; 1.6 +/- 0.9) or controls (1.5 +/- 1.2; p = 0.0001). For values exceeding renal threshold of tubular AA reabsorption (39 microM) the regression line of serum AA to UAA/Cr was significantly (p = 0.001) steeper in diabetics than in controls, suggesting an impaired tubular reabsorption of filtered AA in IDDM. The ratio of AA clearance to CCl was moreover related to AER (r = 0.48; p = 0.03) and to blood glucose (r = 0.51; p = 0.01), being unrelated to uric acid clearance, glycosuria and to urinary excretion of both alanine aminopeptidase and N-acetyl-beta-glucosaminidase.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Absorption; Adult; Albuminuria; Ascorbic Acid; Creatinine; Diabetes Mellitus, Type 1; Female; Humans; Kidney; Kidney Tubules; Male

Topics: Albuminuria; Ascorbic Acid; Bacteriuria; Glycosuria; Hematuria; Humans; Indicators and Reagents; Methods; Reagent Strips; Urine

It has been demonstrated recently that the reaction of serum samples with bromcresol green (BCG) reagent proceeds in two steps. Albumin is responsible for the immediate reaction while other serum proteins produce the slow reaction. In this paper the immediate BCG reaction has been used for the determination of urinary albumin concentration in patients with proteinuria by a slightly modified method with a primary pH adjustment of the urine and the use of a urine blank. Comparison of the immediate BCG method (y) with Laurell "rocket" technique (x) gave the following equation: y = 17.2 + 1.006x (n = 98; r = 0.99) mg/l. The coefficient of variation (within-day), C.V. (%), ranged between 0.9 and 2.7% depending on the albumin concentration. It is thus possible to carry out rapid, accurate and precise albumin determinations in urine samples using this simple method.

Topics: Albuminuria; Ascorbic Acid; Bence Jones Protein; Bromcresol Green; Humans; Hydrogen-Ion Concentration; Immunoassay; Time Factors

Topics: Albuminuria; Ascorbic Acid; Blood Glucose; Carbohydrate Metabolism, Inborn Errors; Diet Therapy; Feces; Fructose; Glucose Tolerance Test; Humans; Infant; Infant Nutrition Disorders; Male; Seizures; Sucrose; Vitamin D; Vomiting

Topics: Acid-Base Equilibrium; Albuminuria; Ascorbic Acid; Bence Jones Protein; Bile Pigments; Bilirubin; Color; Drug Antagonism; Hematuria; Hemoglobinuria; Humans; Indicators and Reagents; Ketone Bodies; Paper; Peroxidases; Phenolphthaleins; Phenols; Povidone; Proteinuria