Low-density lipoprotein oxidizability and the alteration of its fatty acid content in renal transplant recipients treated with cyclosporine/tacrolimus.

Renal transplantation is widely used to treat patients with end-stage renal disease. Atherosclerosis is an important posttransplantation risk factor for renal transplant recipients. Subsequent to transplantation low-density lipoprotein (LDL) particles become susceptible to oxidative modification, which results in atherosclerosis. Therefore, the aim of our study was to investigate differences in the susceptibility of LDL particles to oxidation by analyzing LDL fatty acid levels among renal transplant recipients. The changes in lag phases and fatty acid levels of LDL were observed over 4 months among renal transplant recipients treated with Cyclosporine (CsA; n = 7) or Tacrolimus (FK-506; n = 9). We also analyzed cholesterol and triglyceride levels of patients and healthy controls. The lag phase at the 60th day after transplantation was significantly shorter than the results either before transplantation or among control subjects. In conclusion, a similar decrease in lag phase was observed in both above groups, but the FK-506-treated group showed a better lipid profile than the CsA-treated group.

Evidence of increased oxidative stress by simple measurements in patients with dilated cardiomyopathy.

The heart cannot supply sufficient blood for tissue metabolic needs in patients with congestive heart failure. Hypoxia and organ hypoperfusion increase oxidative activity. It has been reported that free radicals are involved in the genesis of heart failure. The aim of this study was to assess the status of oxidative stress by simple measurements in patients with dilated cardiomyopathy of ischemic or idiopathic etiology. Eleven patients (8 M, 3 F, age range 32 to 65 years) with dilated cardiomyopathy of ischemic etiology and 12 patients (8 M, 4 F, age range 31 to 66 years) with dilated cardiomyopathy of idiopathic etiology were included in the study. A control group included 21 healthy subjects (12 M, 9 F, age range 25 to 67 years). Levels of thiobarbituric acid-reactive substances, total thiols, and fluorescent products of lipid peroxidation were measured in plasma/serum samples of patients and controls. No statistically significant differences were found between the two patient groups for the parameters studied (p>0.05). Levels of thiobarbituric acid-reactive substances and fluorescent products of lipid peroxidation were higher in both patient groups than in controls (p<0.05), whereas concentrations of total thiols were decreased (p<0.05). In conclusion, in patients with idiopathic or ischemic dilated cardiomyopathy, there are associated abnormalities of a range of markers of increased oxidative stress and lipid peroxidation. The plasma/serum constituents studied can be routinely measured in order to monitor patients during antioxidant therapy.

Determination of Ca2+-atpase activity in streptozotocin-induced diabetic rat liver.

Microsomal Ca2+-ATPase activity was studied in control and streptozotocin (STZ)-induced diabetic rat livers. Male rats were rendered diabetic by injection of STZ (45 mg/kg body weight) via the tail vein. Diabetic rats at 1, 4, 8, 10 or 15 wk and control rats were sacrificed. Liver tissues were obtained for the isolation of Ca2+-ATPase. Ca2+-ATPase activity was determined spectrophotometrically and lipid peroxidation [measured as tiobarbituric acid reactive substances (TBARS)] in liver tissues was determined spectrofluorometrically. Total calcium was measured by atomic absorption spectrophotometry. Blood glucose levels of the diabetic animals were >500 mg/dl at 4, 8, 10 and 15 wk of diabetes. Ca2+-ATPase activity was significantly decreased at all weeks of diabetes compared to control group (p<0.001). Ca2+-ATPase activity of control rats was 0.193 +/- 0.015 U/I whereas activity was 0.130 +/- 0.015 U/I at 15 wk of diabetes. The difference in calcium levels of diabetic rat livers was not significantly different compared to control group. On the other hand TBARS were elevated by 67% at 15 wk of diabetes. The decrease in enzyme activity may have been caused by elevated TBARS levels observed in liver tissue sindicative of increased lipid peroxidation.

Ca(2+)-ATPase activity in streptozotocin-induced diabetic rat kidneys.

Kidney Ca(2+)-ATPase activity was altered in streptozotocin (STZ)-induced diabetic rats. Male rats, 200-250 g, were rendered diabetic by injection of STZ 45 mg/kg body weight via the tail vein. Following injection, control rats and diabetic rats at 1, 4, 8 or 15 weeks were sacrificed. Kidney tissues were obtained for the isolation of Ca(2+)-ATPase. Ca(2+)-ATPase activity was determined spectrophotometrically. Total calcium was measured by atomic absorption spectrophotometry. Diabetic rats had significantly elevated blood glucose levels compared to controls. Blood glucose levels were 92.92 +/- 1.215 mg/dl (mean +/- S.E.M.) for the control group, and 362.50 +/- 9.613 mg/dl at one week and > 500 mg/dl at 4, 8 and 15 weeks of diabetes. Enzyme activities were significantly higher at 4, 8 and 15 weeks of diabetes than in the control group (p < 0.001). There was no significant increase at one week of diabetes. Ca(2+)-ATPase activity was 0.43 +/- 0.003 U/L, 0.517 +/- 0.058 U/L, 0.707 +/- 0.078 U/L, 0.730 +/- 0.006 U/L and 0.715 +/- 0.055 U/L respectively for controls and rats at 1, 4, 8 and 15 weeks of diabetes. Calcium levels in diabetic rat kidneys were also significantly higher than for controls. The increase in enzyme activity may have been caused by higher calcium levels in diabetic kidneys resulting from a compensatory response of the enzyme to high levels of the ion.

Increased oxidative stress in dilated cardiomyopathic heart failure.

In the present study, we assessed oxidative stress in patients with dilated cardiomyopathy of ischemic or idiopathic etiology. For this reason we measured whole blood reduced glutathione, erythrocyte superoxide dismutase, susceptibility of erythrocyte membranes and erythrocytes to peroxidation, and SH content of erythrocyte membranes in 12 patients (8 men and 4 women, ages 31 to 66 years) with idiopathic dilated cardiomyopathy, in 11 patients (8 men and 3 women, ages 32 to 65 years) with ischemic dilated cardiomyopathy, and in 21 healthy volunteers (12 men and 9 women, ages 25 to 67 years). There was no statistically significant difference between the two patient groups for the indicators studied (P >0.05). Blood glutathione, erythrocyte superoxide dismutase, and membrane SH content of both groups of patients was decreased compared with controls (P <0.05), whereas erythrocyte and membrane susceptibility to peroxidation were increased (P <0.05). We conclude that patients with idiopathic or ischemic dilated cardiomyopathy exhibit abnormalities of a range of markers of increased oxidative stress. These abnormalities may contribute to contractile dysfunction, increased incidence of fatal arrhythmias, and sudden death.

Calmodulin glycation in diabetic rat lenses.

The activation of phosphodiesterase by calmodulin isolated from diabetic rat lens tissue was determined. Male rats, 200-250 g, were rendered diabetic by injection of streptozotocin (45 mg/kg body weight) via the tail vein. After the onset of diabetes, the animals were observed for 15 weeks. Compared with a blood glucose level of 94.84 +/- 2.72 mg/dL in the control group, 1, 4, and 6 week diabetic rats had blood glucose levels of 357.00 +/- 7.55, 366.53 +/- 4.76, and 366.57 +/- 5.30 mg/dL, and 8, 10, and 15 week diabetic rats had levels over 400 mg/dL. After collecting the lens tissue, boiled extracts were prepared as a calmodulin source and were applied to a Glycogel B column for separating glycosylated and nonglycosylated calmodulin. Calmodulin activities of boiled extracts and glycosylated eluates were determined via the activation of calmodulin-deficient brain phosphodiesterase. Calmodulin activities of diabetic rat lenses were significantly reduced compared with the control group. The results of glycosylated protein determination with the thiobartiuric acid method were in accordance with calmodulin activities. Calmodulin activities of the diabetic lens tissues were reduced, while the protein glycosylation levels were elevated.

Effect of vitamin C on copper and iron status in men and guinea pigs.

Healthy individual were given 2 g of vitamin C per day for 2 months. Whole blood iron, ascorbic acid, hemoglobin, and serum ceruloplasmin were determined at the beginning, and 1 or 2 months after the start of the experiment. The concentration of ascorbic acid was observed to increase significantly in the blood, while blood iron, hemoglobin, and serum ceruloplasmin levels significantly increased at the end of the 1st month, but decreased to control levels at the end of the 2nd month. Male albino guinea pigs were administered 8, 180, and 360 mg of vitamin C per day for 2 months. Liver ferritin iron, liver copper, serum copper, and serum ceruloplasmin levels significantly decreased, but there was no significant change in hemosiderin iron while blood ascorbic acid significantly increased at the end of the 2 month period. There was no significant change in serum iron and hematocrit levels. These results suggest that vitamin C has an antagonistic effect on copper metabolism in guinea pigs but not in humans either on copper or iron metabolisms.

Effect of vanadium compounds on calmodulin activity in experimental diabetes in rats.

Vanadate and vanadyl have been reported to have insulin-like properties and have recently been demonstrated to be beneficial in the treatment of diabetic animals. In this study, we determined whether vanadium ions mimic the effect of insulin on calmodulin activity of liver and adipose tissues in streptozotocin-induced diabetic rats and examined their effect with respect to concentration and time. Calmodulin activities in the hormone-sensitive tissues decreased in diabetes and returned to normal after sodium metavanadate or vanadyl sulfate treatment for 3 weeks (0.2, 0.4, and 0.8 mg/mL in drinking water). These results demonstrate that V5+ and V4+ forms of vanadium can restore the activity of calmodulin in experimental diabetes induced by streptozotocin.

Vitamin C aspirin interactions in laboratory animals.

Ascorbic acid concentration has been determined in samples of plasma, leucocytes, urine, faeces and adrenal glands of guinea-pigs after administration of (i) 10, 25 or 100 mg ascorbic acid, (ii) 10 mg ascorbic acid plus 10, 25 or 50 mg aspirin and (iii) 25 mg aspirin and 25, 50 or 100 mg ascorbic acid. When the dose of aspirin was 25 mg or more, the transport of ascorbic acid into leucocytes was inhibited, the plasma concentration of vitamin C was elevated significantly and the excretion of ascorbic acid in the urine was increased in direct proportion to the aspirin dose. Ascorbic acid concentration in the adrenal glands was not significantly elevated after 3 h. When a constant dose of 25 mg of aspirin was given along with increasing doses of ascorbic acid both plasma and leucocyte ascorbic acid levels were elevated but not significantly after 2, 3 and 24 h. Urine ascorbic acid levels did not show any changes with the same doses.

Mechanisms underlying enhanced glycogenolysis in livers of 3,5,3'-triiodothyronine-treated rats.

Rats trained on a diurnal controlled meal-feeding schedule and injected with a single dose of 3,5,3'-triiodothyronine (T3) failed to accumulate liver glycogen and incorporated less D-[6-3H]glucose into glycogen than normally observed during the feeding period. In the experimental group, the concentration of liver adenosine 3',5'-cyclic monophosphate (cAMP) did not fall during feeding and the pattern of activities of glycogen phosphorylase, glycogen synthase, and phosphorylase kinase remained conductive to glycogenolysis. Liver lysosomal alpha-glucosidase activity normally fell during feeding periods. After T3 treatment the activities of alpha-glucosidase and two lysosomal cathepsins (B1 and D) were elevated. The evidence suggests that T3 may induce both liver phosphorylase kinase and lysosomal alpha-glucosidase. This outcome of T3 excess, in concert with previously described T3-inducible systems, provides a plausible explanation for the failure of glycogen accumulation in this experimental model.

Effects of ascorbic acid supplementation on liver, lung and kidney microsomal drug metabolizing enzymes of the guinea-pig.

1. Male guinea-pigs were administered 8, 180 and 360 mg ascorbic acid/day via drinking water for 1 and 2 months. The two high levels of ascorbic acid were not able to produce saturation in either blood or any of the three tissues (liver, lung and kidney) while the lowest ascorbic acid level was sufficient to prevent scurvy. 2. There was no significant differences among the groups receiving three distinct ascorbic acid levels in body weights, tissue weights or protein contents. 3. No significant alterations were observed in microsomal ethylmorphine N-demethylase activity of any of the three tissues among the groups after experimental periods. 4. The two high ascorbic acid levels produced significant increases in liver microsomal aniline 4-hydroxylase activity as compared to the lowest supplementation of ascorbic acid after 2 months. However, no significant enzyme activity changes were found among the groups after 1 month. 5. In lung, after 1 month significant increase was observed in microsomal aniline 4-hydroxylase activity with the two high ascorbic acid levels as compared to the lowest supplementation of ascorbic acid whereas after 2 months no significant changes were observed. 6. Kidney microsomal aniline 4-hydroxylase activity was unaffected by changes in ascorbate status.

Effects of vitamin C intake on whole blood plasma, leucocyte and urine ascorbic acid and urine oxalic acid levels.

Fifty volunteers among the students of the Faculty of Pharmacy at Ankara and Gazi Universities were taken 2 grams of Vitamin C per day at regular time intervals for two months. Blood and urine samples were collected in the beginning, one month and 2 months after vitamin administration. The whole blood, plasma and leucocyte ascorbic acid levels were increased after one and 2 months treatment. The urine ascorbic acid were also increased significantly. Urine oxalic acid were not elevated after vitamin C intake.

Ascorbic acid effect on some lipid fractions in human beings.

A group of 50 volunteers of our Faculty students have taken Vitamin C 2 g per day at regular time intervals for 2 months. Blood samples were taken in the beginning, one month and 2 months after vitamin administration. Cholesterol, HDL-cholesterol, lipoprotein and triglyceride concentrations were determined. Cholesterol concentrations were decreased significantly at the end of treatment. Triglyceride concentrations were decreased also in first and second month. HDL-cholesterol were rised significantly and alpha and beta fractions of lipoprotein were increased.