Protective effects of vitamin C, alone or in combination with vitamin A, on endotoxin-induced oxidative renal tissue damage in rats

This study was designed to investigate the protective effects of vitamin C and vitamin A on oxidative renal tissue damage. Male Wistar rats were given an intraperitoneal injection of 0.5 ml saline (control) or 0.5 ml solution of lipopolysaccharide (10 mg/kg), which caused endotoxemia. Immediately (within 5 min) after the endotoxin injection, the endotoxemic rats were untreated or treated with intraperitoneal injection of vitamin A (195 mg/kg bw), vitamin C (500 mg/kg bw) or their combination. After 24 hours, tissue and blood samples were obtained for histopathological and biochemical investigation. Endotoxin injection caused renal tissue damage and increased erythrocyte and tissue malondialdehyde (MDA) and serum nitric oxide (NO), urea and creatinine concentrations, but decreased the superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) activities compared to the parameters of control animals. Treatment with vitamin C or with vitamins C and A significantly decreased the MDA levels and serum NO, urea and creatinine levels, recovered the antioxidant enzyme activities (SOD, GSH-Px and CAT), and prevented the renal tissue damage in endotoxemic rats. In contrast, vitamin A alone did not change the altered parameters except for creatinine levels. Notably, the better effects were observed when vitamins A and C given together. It is concluded that vitamin C treatment, alone or its combination with vitamin A, may be beneficial in preventing endotoxin-induced oxidative renal tissue damage and shows potential for clinical use.     

维生素C和芦丁对力竭运动小鼠组织自由基代谢的影响

目的：观察注射维生素C和芦丁后,急性疲劳性游泳运动小鼠机体各组织自由基代谢的变化情况.方法：实验于2004-09/12在泰山医学院基础医学研究所完成,选择雄性小鼠32只,随机分为4组,分别为生理盐水组、芦丁组、维生素C组和维生素C＋芦丁组,每组8只.生理盐水组每天注射等量生理盐水,芦丁组注射芦丁5 mg/d,维生素C组注射维生素C 8 mg/d,维生素C＋芦丁组每天注射芦丁5 mg和维生素C 8 mg,持续15 d.各组小鼠进行池中游泳至力竭,力竭标准：动物不能在水中保持上浮,开始下沉,取出后尾部受刺激逃避呈踉跄步态,身体不能保持平衡,但呼吸心跳存在.麻醉后断头处死,测定小鼠脑、心、肝、肾和骨骼肌中丙二醛含量和超氧化物歧化酶活性分别采用硫代巴比妥酸比色法和氮蓝四唑光还原法.结果：所有小鼠全部进入结果分析,无脱失.①各组小鼠运动耐力比较：芦丁组、维生素C组及维生素C＋芦丁组小鼠的耐力时间显著长于生理盐水组[（52.51&;#177;8.97,50.50&;#177;7.23和60.15&;#177;9.54,42.10&;#177;6.32）min（χ^2=18.48～19.11,P＜0.01）].②各组小鼠各组织丙二醛/超氧化物歧化酶比值比较：芦丁组、维生素C组和维生素C＋芦丁组小鼠心、肾、肝和肌组织中比值均显著低于生理盐水组（χ^2=14.20～16.00,P＜0.05）,但维生素C＋芦丁组的比值显著低于芦丁组和维生素C组（χ^2=18.50～20.13,P＜0.01）.结论：维生素C和芦丁均可降低丙二醛/超氧化物歧化酶比值,减少力竭运动后因脂质过氧化而产生的自由基,延长机体过度运动的耐力,但两者混合使用效果更好.     

维生素C和芦丁对力竭运动小鼠组织自由基代谢的影响

目的:观察注射维生素C和芦丁后,急性疲劳性游泳运动小鼠机体各组织自由基代谢的变化情况。方法:实验于2004-09/12在泰山医学院基础医学研究所完成,选择雄性小鼠32只,随机分为4组,分别为生理盐水组、芦丁组、维生素C组和维生素C+芦丁组,每组8只。生理盐水组每天注射等量生理盐水,芦丁组注射芦丁5mg/d,维生素C组注射维生素C8mg/d,维生素C+芦丁组每天注射芦丁5mg和维生素C8mg,持续15d。各组小鼠进行池中游泳至力竭,力竭标准:动物不能在水中保持上浮,开始下沉,取出后尾部受刺激逃避呈踉跄步态,身体不能保持平衡,但呼吸心跳存在。麻醉后断头处死,测定小鼠脑、心、肝、肾和骨骼肌中丙二醛含量和超氧化物歧化酶活性分别采用硫代巴比妥酸比色法和氮蓝四唑光还原法。结果:所有小鼠全部进入结果分析,无脱失。①各组小鼠运动耐力比较:芦丁组、维生素C组及维生素C+芦丁组小鼠的耐力时间显著长于生理盐水组[(52.51±8.97,50.50±7.23和60.15±9.54,42.10±6.32)min(χ2=18.48～19.11,P<0.01)]。②各组小鼠各组织丙二醛/超氧化物歧化酶比值比较:芦丁组、维生素C组和维生素C+芦丁组小鼠心、肾、肝和肌组织中比值均显著低于生理盐水组(χ2=14.20～16.00,P<0.05),但维生素C+芦丁组的比值显著低于芦丁组和维生素C组(χ2=18.50～20.13,P<0.01)。结论:维生素C和芦丁均可降低丙二醛/超氧化物歧化酶比值,减少力竭运动后因脂质过氧化而产生的自由基,延长机体过度运动的耐力,但两者混合使用效果更好。     

Functional involvement of rat organic anion transporter 3 (rOat3; Slc22a8) in the renal uptake of organic anions

Our previous kinetic analyses have shown that the transporter responsible for the renal uptake of pravastatin, an HMG-CoA reductase inhibitor, differs from that involved in its hepatic uptake. Although organic anion transporting polypeptides are now known to be responsible for the hepatic uptake of pravastatin, the renal uptake mechanism has not been clarified yet. In the present study, the involvement of rat organic anion transporter 3 (rOat3; Slc22a8) in the renal uptake of pravastatin was investigated. Immunohistochemical staining indicates the basolateral localization of rOat3 in the kidney. rOat1- and rOat3-expressed LLC-PK1 cells exhibited specific uptake of p-aminohippurate (PAH) and pravastatin, respectively, with the Michaelis-Menten constants (Km values) of 60 microM for rOat1-mediated PAH uptake and 13 microM for rOat3-mediated pravastatin uptake. Saturable uptake of PAH and pravastatin was observed in kidney slices with Km values of 69 and 11 microM, respectively. The difference in the potency of PAH and pravastatin in inhibiting uptake by kidney slices suggests that different transporters are responsible for their renal uptake. This was also supported by the difference in the degree of inhibition by benzylpenicillin, a relatively selective inhibitor of rOat3, for the uptake of PAH and pravastatin by kidney slices. These results suggest that rOat1 and rOat3 are mainly responsible for the renal uptake of PAH and pravastatin, respectively.     

Hepatitis C is a predictor of poorer renal survival in diabetic patients

OBJECTIVE: Hepatitis C virus (HCV) is highly prevalent in the U.S. and worsens renal survival in some kidney diseases. We examined the effects of HCV on renal survival in diabetic patients with renal disease. RESEARCH DESIGN AND METHODS: HCV and diabetes status were noted in patients seen in our nephrology clinic in 2001 and 2002. Charts of diabetic patients were reviewed for demographics, blood pressure, renal function, medicines, the presence of HCV, and other factors at the initial visit and over follow-up. The effect of HCV on renal survival was determined by Cox proportional hazards, using end-stage renal disease (ESRD) as an end point. RESULTS: Of 1,127 patients, prevalence rates for HCV were higher in African Americans than non-African Americans (8.09 vs. 3.93%, respectively, P = 0.06), with African-American men having the highest prevalence rates (12.7%). The charts of 312 diabetic patients were reviewed. Over 80% were African American, as were 23 of 24 patients with HCV. Compared with non-HCV patients, HCV patients were younger, had higher diastolic blood pressure, and had lower BMI. HCV patients had significantly worse cumulative renal survival by Kaplan-Meier. On Cox proportional hazards analysis, HCV was a significant predictor of reaching ESRD independent of initial renal function, proteinuria, blood pressure, sex, race, presence of diabetic nephropathy, age, or duration of diabetes (odds ratio 3.49, 95% CI 1.27-9.57, P = 0.015). CONCLUSIONS: HCV is common in African Americans with diabetes and renal disease and is an independent risk factor for renal survival in this population. Prospective studies are necessary to confirm these observations.     

Vitamin C supplementation in the patient with burns and renal failure.

Vitamin C supplementation is an important component of nutritional management in patients with burns. To supply appropriate vitamin C therapy, complications such as renal failure must be considered. An understanding of current vitamin regimens and potential metabolic sequelae can assist the practitioner in providing safe and therapeutic vitamin C doses.     

Leukocyte accumulation and changes in extra-renal organs during renal ischemia reperfusion in mice

Multiorgan failure is a life threatening complication in patients with ischemic acute renal failure (ARF). However, little is known about the underlying multiorgan system cellular immunity in ischemic ARF. We therefore studied the dynamics of cells accumulating in the kidneys and other organs in mice and analyzed the characteristics of the accumulated cells. We prepared a unilateral renal ischemia/reperfusion injury (IRI) model in C57BL/6 or C3H/He mice. At 1 to 3 hours after renal ischemia, increased accumulations of neutrophils and intermediate T cells were observed in the clamped kidney, but the same phenomena were also observed in the nonclamped kidney, liver, and spleen. After 24 hours, these cell numbers had returned to preischemic levels, but remained elevated for a longer period in the clamped kidney. The intermediate T cells that accumulated in the kidney and liver in the IRI mice expressed higher Vbeta chains specific to forbidden clones than in the control mice. Moreover, the accumulated intermediate T cells in the IRI liver had cytotoxic activity against both tumor cells and syngeneic thymocytes. In the clamped kidney, the accumulated intermediate T cells had less cytotoxic activity against tumor cells; however, the expression of the Fas ligand (FasL) increased, indicating a cell-mediated tissue injury via the Fas/FasL system. Histopathologically, an influx of neutrophils and lymphocytes was observed not only in the clamped kidney but also in the hepatic sinusoids concomitantly with liver dysfunction. These findings indicate that a systemic cellular immune response, including intermediate T cells, affects multiple organs during ischemic ARF, which may play an important role in the development of multiorgan failure.     

Role of complement receptors 1 and 2 (CD35 and CD21), C3, C4, and C5 in survival by mice of Staphylococcus aureus bacteremia

Complement-mediated opsonization and phagocytosis of encapsulated serotype 5 Staphylococcus aureus are essential to host defense. We describe the effects of complement depletion and deficiencies of C4, C5, and complement receptors 1 and 2 on mouse survival after intravenous exposure to S aureus. Depletion of complement proteins in C57BL/6 mice with the use of cobra-venom factor decreased survival compared with that of controls after the induction of bacteremia with mucoid (90% mortality), encapsulated (73%), and unencapsulated (59%) S aureus strains. In this model complement is even more important in the control of infection with encapsulated S aureus (80% of clinical isolates) than in the control of infection by unencapsulated strains. C4-deficient mice demonstrated similar mortality from bacteremia caused by encapsulated S aureus compared with controls, suggesting that in the unimmunized animal the alternative complement pathway contributes more to control of bacteremia caused by encapsulated S aureus than the classical complement pathway or mannan-binding lectin pathway. C5-deficient mice (B10.D2-H2(d) H2-T18(c) Hc(0)/oSnJ) showed similar mortality when subjected to bacteremia caused by encapsulated S aureus compared with C5-sufficient (B10.D2-Hc(1) H2(d) H2-T18(c)/nSnJ) mice, suggesting that in this model the anaphylatoxin C5a and the late complement cascade are not critical to survival of bacteremia induced with the use of these strains. However, C5-deficient mice depleted of C3 with the use of cobra-venom factor had 60% decreased survival compared with untreated C5-deficient mice with bacteremia induced by encapsulated S aureus, suggesting that in this model C3 is more critical than C5 in controlling S aureus bacteremia. Complement receptor 1 (CD35) is the primary receptor for the opsonin C3b. Mice deficient in CD35/CD21 showed a 67% decrease in survival compared with normal mice, suggesting that CD35/CD21 is of major importance in the control of S aureus-induced bacteremia.     

FGF 23, PTH and vitamin D status in end stage renal disease patients affected by VDR FokI and BsmI variants

ObjectivesThe aim of this study was to evaluate the association between two VDR SNPs FokI and BsmI and mineral status in ESRD patients.Design and methodsOur case-control study included 100 patients with chronic renal failure in ESRD and 149 healthy subjects. We measured the serum Vitamin D levels and the serum intact PTH level by Electrochemiluminescence Technology (cobas E411 analyzer). We evaluated the serum FGF23 levels by indirect ELISA method. The genotyping of two VDR gene variants FokI and BsmI was carried out by PCR-RFLP technique.ResultsIn our study, the FokI TT genotype was associated with lower risk of ESRD development (OR = 0.176, Padj = 0.039). The difference in PTH and FGF23 levels between cases and controls was statistically significant. The expression of FokI CT genotype in subjects with diabetic nephropathy was associated with a negative correlation between VD and PTH levels (r = −0.620, P = 0.032) and a positive correlation between VD and FGF23 levels (r = 0.967, P = 0.012). A significant differences in VD levels between patients and controls was observed in the presence of FokI TT (P = 0.044) and CT (P = 0.036) genotypes. The expression of FGF23 serum level was significantly elevated in patients than in controls in the presence of the FokI CC and BsmI AG genotypes.ConclusionsIn conclusion, our study shows the existence of an association between VDR FokI, BsmI polymorphisms and mineral status in ESRD patients. The presence of VDR variants affect the protein expression of VD, phosphorus, FGF23 and PTH.     

Vitamin A toxicity and vitamin E deficiency in a rabbit colony.

Vitamin A toxicosis and vitamin E deficiency was diagnosed in a commercial rabbit-breeding colony and was associated with reproductive abnormalities, abortions, and poor survivability of kits in the breeding colony. Paresis and muscular dystrophy were noted in juvenile rabbits. Another group of New Zealand White rabbits from the same commercial colony was used to assess the effect of vitamin E-based therapy on clinical signs, reproduction, and vitamin A and E serum and liver levels. Blood samples were taken before and after dietary changes and vitamin E therapy. Serum vitamin E remained low after feeding a diet containing the recommended levels of vitamin E. Administration of vitamin E for 2 weeks lowered the serum vitamin A levels and increased the vitamin E serum and liver levels. In conclusion, vitamin E therapy appears to be an effective treatment for hypervitaminosis A.     

ENT1, a ribavirin transporter, plays a pivotal role in antiviral efficacy of ribavirin in a hepatitis C virus replication cell system

We previously showed that equilibrative nucleoside transporter 1 (ENT1) is a primary ribavirin transporter in human hepatocytes. However, because the role of this transporter in the antiviral mechanism of the drug remains unclear, the present study aimed to elucidate the role of ENT1 in ribavirin antiviral action. OR6 cells, a hepatitis C virus (HCV) replication system, were used to evaluate both ribavirin uptake and efficacy. The ribavirin transporter in OR6 cells was identified by mRNA expression analyses and transport assays. Nitrobenzylmercaptopurine riboside (NBMPR) and micro-RNA targeted to ENT1 mRNA (miR-ENT1) were used to reduce the ribavirin uptake level in OR6 cells. Our results showed that ribavirin antiviral activity was associated with its accumulation in OR6 cells, which was also closely associated with the uptake of the drug. It was found that the primary ribavirin transporter in OR6 cells was ENT1 and that inhibition of ENT1-mediated ribavirin uptake by NBMPR significantly attenuated the antiviral activity of the drug as well as its accumulation in OR6 cells. The results also showed that even a small reduction in the ENT1-mediated ribavirin uptake, achieved in this case using miR-ENT1, caused a significant decrease in its antiviral activity, thus indicating that the ENT1-mediated ribavirin uptake level determined its antiviral activity level in OR6 cells. In conclusion, our results show that by facilitating its uptake and accumulation in OR6 cells, ENT1 plays a pivotal role in the antiviral effectiveness of ribavirin and therefore provides an important insight into the efficacy of the drug in anti-HCV therapy.     

Effect of vitamin E and vitamin C supplementation on antioxidative state and renal glomerular basement membrane thickness in diabetic kidney

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.