Navegando por Palavras-chave "vitamin C"

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    Antioxidant vitamins C and E supplementation increases markers of haemolysis in sickle cell anaemia patients: a randomized, double-blind, placebo-controlled trial
    (Wiley-Blackwell, 2013-03-01) Arruda, Martha M. [UNIFESP]; Mecabo, Grazielle [UNIFESP]; Rodrigues, Celso A. [UNIFESP]; Matsuda, Sandra S. [UNIFESP]; Rabelo, Iara B. [UNIFESP]; Figueiredo, Maria S. [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Erythrocytes from sickle cell anaemia (SCA) patients continuously produce larger amounts of pro-oxidants than normal cells. Oxidative stress seems to primarily affect the membrane and results in haemolysis. the use of antioxidants in vitro reduces the generation of pro-oxidants. To evaluate the impact of vitamins C (VitC) and E (VitE) supplementation in SCA patients, patients over 18years were randomly assigned to receive VitC 1400mg+VitE 800mg per day or placebo orally for 180d. Eighty-three patients were enrolled (44 vitamins, 39 placebo), median age 27 (1868) years, 64% female. There were no significant differences between the two groups regarding clinical complications or baseline laboratorial tests. Sixty percent of the patients were VitC deficient, 70% were VitE deficient. Supplementation significantly increased serum VitC and E. However, no significant changes in haemoglobin levels were observed, and, unexpectedly, there was a significant increase in haemolytic markers with vitamin supplementation. in conclusion, VitC+VitE supplementation did not improve anaemia and, surprisingly, increased markers of haemolysis in patients with SCA and S-0-thalassaemia. the exact mechanisms to explain this findings and their clinical significance remain to be determined.
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    Effect of vitamin C supplements on urinary oxalate and pH in calcium stone-forming patients
    (Blackwell Publishing Inc, 2003-03-01) Baxmann, Alessandra Calábria [UNIFESP]; Mendonça, Cláudia de Oliveira Guimarães [UNIFESP]; Heilberg, Ita Pfeferman [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Background. the contribution of ascorbate to urinary oxalate is controversial. the present study aimed to determine whether urinary oxalate and pH may be affected by vitamin C supplementation in calcium stone-forming patients.Methods. Forty-seven adult calcium stone-forming patients received either 1 g (N = 23) or 2 g (N = 24) of vitamin C supplement for 3 days and 20 healthy subjects received 1 g. A 24-hour urine sample was obtained both before and after vitamin C for calcium, oxalate, magnesium, citrate, sodium, potassium, and creatinine determination. the Tiselius index was used as a calcium oxalate crystallization index. A spot fasting morning urine sample was also obtained to determine the urinary pH before and after vitamin C.Results. Fasting urinary pH did not change after 1 g (5.8 +/- 0.6 vs. 5.8 +/- 0.7) or 2 g vitamin C (5.8 +/- 0.8 vs. 5.8 +/- 0.7). A significant increase in mean urinary oxalate was observed in calcium stone-forming patients receiving either 1 g (50 +/- 16 vs. 31 +/- 12 mg/24 hours) or 2 g (48+/- 21 vs. 34 +/- 12 mg/24 hours) of vitamin C and in healthy subjects (25 +/- 12 vs. 39 +/- 13 mg/24 hours). A significant increase in mean Tiselius index was observed in calcium stone-forming patients after 1 g (1.43 +/- 0.70 vs. 0.92 +/- 0.65) or 2 g vitamin C (1.61 +/- 1.05 vs. 0.99 +/- 0.55) and in healthy subjects (1.50 +/- 0.69 vs. 0.91 +/- 0.46). Ancillary analyses of spot urine obtained after vitamin C were performed in 15 control subjects in vessels with or without ethylenediaminetetraacetic acid (EDTA) with no difference in urinary oxalate between them (28 +/- 23 vs. 26 +/- 21 mg/L), suggesting that the in vitro conversion of ascorbate to oxalate did not occur.Conclusion. These data suggest that vitamin C supplementation may increase urinary oxalate excretion and the risk of calcium oxalate crystallization in calcium stone-forming patients.
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    Vitamin C prevents DNA damage induced by renovascular hypertension in multiple organs of Wistar rats
    (Sage Publications Ltd, 2010-07-01) Nishi, Erika Emy [UNIFESP]; Campos, Ruy Ribeiro [UNIFESP]; Bergamaschi, Cassia Toledo [UNIFESP]; Almeida, Vitor Rossi de [UNIFESP]; Ribeiro, Daniel Araki [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The aim of this study was to investigate, through the single-cell gel (comet) assay, whether vitamin C is able to protect against renovascular hypertension-induced genotoxicity in multiple organs. A total of 32 male Wistar rats were divided into four groups: negative control (n = 6); animals treated with vitamin C (n = 6); hypertensive rats (n = 10) and hypertensive rats and treated with vitamin C (n = 10). Hypertension was induced as a result of partial obstruction of the left renal artery by means of a silver clip during 6 weeks. Vitamin C was administered at 150 mg/kg during 7 consecutive days before the end of the experimental period. the results showed that vitamin C was able to protect blood cells against hypertension-induced genotoxicity. Brain, liver and heart cells were also protected by vitamin C following hypertension-induced genotoxic damage. Regarding blood pressure, vitamin C reduced the hypertensive state. in conclusion, our results suggest that vitamin C can prevent hypertension-induced DNA damage in blood, liver, brain and heart cells as well as to normalize the blood pressure of rats.