The kidney is the target for a wide variety of chemical agents, including heavy metals, haloalkenes, analgesics and antibiotics. The functional and metabolic characteristics of the proximal tubule (PT) predispose it as the primary site for xenobiotic damage. The aim of this study was to isolate and characterise human and rat PT cells in suspension and primary culture for use as defined models to investigate drug-induced PT cell damage in vitro . A second aim was to compare the response of human and rat systems to known nephrotoxins. Human and rat PT cells (90&'37 viable) were isolated from kidney cortex by collagenase digestion followed by isopycnic Percoll density centrifugation. This resulted in the formation of two distinct bands of cell at densities 1.040g/ml (A) and 1.060g/ml (B) for both preparations. Characterisation of human cells in terms of morphology, marker enzymes, retention of active transport systems and responsiveness to parathyroid hormone indicated that &'62 95&'37 of the cells in band B were proximal tubular. Each transport system demonstrated Michaelis-Menten kinetics; kinetic parameters suggested that a higher proportion of PT cells from the S1-S2 segment of the nephron were present in human isolates. Human isolated cells also contained levels of glutathione and cytochrome P450, in particular ethoxyresorufin-O-deethylase activity, a marker for the P4501A family, similar to the intact kidney. Both human and rat cells were successfully cultured in serum-supplemented medium (10&'37 v/v) with human cells reaching confluence by 3-4 days and rat by 5-6. Maximal attachment was seen when cells from both preparations were inoculated onto collagen coated plates with an additional layer of fibronectin. Only human cells were able to reach confluence on porous membranes and demonstated an enhanced morphology when compared to normal cultured cells. Cultured cells from both preparations retained an epithelial morphology and showed minimal secondary cell contamination as shown by light microscopy and in the case of human cultures additionally through immunohistochemical staining. Immunohistochemical staining also demonstrated that human cells in culture were depositing components of the extracellular matrix. The maintenance of PT cell function, throughout the time in culture, was shown following maintenance of active transport systems, in particular the glucose carrier system and on porous membranes the organic anion system. Only rat cells maintained the organic cation system in primary culture. In addition human cells maintained the preferential response to parathyroid hormone. Except for the transport of organic cations, the other carrier systems and responsiveness to hormones were evident at both sub-confluent and confluent stages of cell culture.

No description available.

The effects of diabetes on cytochrome P450 dependent drug metabolizing enzymes have not to be clarified yet. The most widely used animals in these studies have been rats, and information regarding the effects of diabetes on cytochrome P450 dependent procarcinogen/carcinogen metabolism in rabbits is limited. In the present study, we investigated, for the first time, the influence of benzene on liver, kidney and lung microsomal cytochrome P450 dependent drug metabolizing enzyme activities, protein and mRNA levels in diabetic and non-diabetic rabbits. Male New Zealand rabbits were made diabetic by a single dose of alloxan treatment in this study. AST, ALT and LDH enzyme activities in the blood serum and lipid peroxidation in liver microsomes were found to increase in diabetic, benzene treated and benzene treated diabetic rabbits. Besides these, CYP2E1 dependent NDMA N-demethylase and p-nitrophenol hydroxylase activities and CYP2E1 protein level were found to increase in liver and kidney of diabetic and benzene-treated rabbits. The combined effects of benzene and diabetes on these activities and protein level were found to be additive. Although diabetes caused induction of pulmonary CYP2E1 protein level and associated enzyme activities, benzene treatment of rabbits resulted in no change in enzyme activities and protein level in lung. The level of mRNA was investigated by Real-Time PCR. Accordingly, hepatic CYP2E1 mRNA level was increased 6.71-, 10.53- and 12.93-fold in diabetic, benzene treated and benzene treated diabetic rabbits with respect to the control animals. Similarly, renal CYP2E1 mRNA level was found in increase in these rabbits. In addition to CYP2E1, CYP3A6 associated enzyme activity, erythromycin N-demethylase, CYP3A6 protein and mRNA level were found to increase in diabetic rabbit liver and lung. Unlike diabetes, benzene treatment caused suppression of CYP3A6 protein and inhibition of associated enzyme activity in liver. There was no significant change in the erythromycin N-demethylase activity and CYP3A6 level of liver and lung as a result of benzene treatment of diabetic rabbits. Moreover, diabetes induced CYP1A2 protein and mRNA level and CYP1A associated enzyme activities in the rabbit liver. On the other hand, benzene caused statistically insignificant decreases in CYP1A dependent enzyme activities and CYP1A2 protein level in liver. CYP1A associated enzyme activities, CYP1A2 protein and mRNA levels were not changed in the liver of benzene treated diabetics. The results of the present work indicate that both diabetes and benzene stimulate metabolic activation toxic chemicals metabolized by CYP2E1 such as NDMA and benzene by inducing CYP2E1 which results in the formation of increased amounts of reactive metabolites. Application of benzene to diabetic rabbits further elevates expression and activities of the CYP2E1. As a result of additive induction of the CYP2E1 in benzene treated diabetics, further increase the risk of hepatotoxicity produced by toxins may be observed when compared to the separate treatments. This may in turn further potentiate the risk of organ toxicity and mutagenesis in liver and kidney of these subjects. As in the case of CYP2E1, the risk of carcinogenesis due to induction of CYP1A may be increased in diabetic subjects. Moreover, in diabetic and benzene exposed subjects, alteration of drug clearance and clinical drug toxicity may be observed due to induction or suppression of CYP3A.

As infecções fúngicas invasivas (IFIs) são um problema de saúde pública e representam uma importante causa de morbidade e mortalidade. A Anfotericina B (AnfB) é a droga de escolha no tratamento das IFIs. Apesar da sua eficácia, a AnfB está associada com efeitos adversos como a nefrotoxicidade. Com o número elevado de pacientes suscetíveis às IFIs, estudos foram desenvolvidos e demonstraram que a nefrotoxicidade pode ser prevenida através do uso de AnfBs modificadas. Dessas modificações, a AnfB incorporada à uma emulsão lipídica (AnfB/EL) apresenta baixo custo e similar eficácia. Existe uma alta prevalência de deficiência de vitamina D (dVD) na população mundial. Sendo assim, a hipovitaminose D pode acelerar a progressão da doença renal e refletir em mau prognóstico em casos de nefrotoxicidade. Esse trabalho visa analisar se a deficiência da vitamina D pode induzir a nefrotoxicidade da AnfB/EL. Ratos Wistar foram divididos em quatro grupos: controle, animais que receberam dieta padrão por 34 dias; AnfB/EL, animais que receberam dieta padrão por 34 dias e injeção intraperitoneal de AnfB/EL (5mg/kg/dia) nos últimos 4 dias; dVD, animais que receberam dieta depletada em vitamina D por 34 dias; e dVD+AnfB/EL, animais que receberam dieta depletada em vitamina D por 34 dias e a injeção intraperitoneal de AnfB/EL (5mg/kg/dia) nos últimos 4 dias. Amostras de sangue, urina e tecido renal foram coletadas para a análise dos efeitos da droga sobre a função, hemodinâmica e morfologia renal. A associação de AnfB/EL com a hipovitaminose D levou a injúria renal, lesão tubular discreta, hiperfosfatúria, hipermagnesiúria, hipertensão e comprometimento do mecanismo de concentração urinária. Dessa forma, é essencial monitorar os níveis de vitamina D em pacientes tratados com AnfB/EL, uma vez que a deficiência dessa vitamina é um fator indutor de nefrotoxicidade associada ao uso da AnfB/EL / Invasive fungal infections (IFI) have become a worldwide serious health problem and represent a significant cause of morbidity and mortality. Amphotericin B (AmB) is the drug of choice for the treatment of IFI. Despite its efficacy, use of AmB has been associated with adverse reactions such as nephrotoxicity The increasing number of high-risk patients, who are more susceptible to IFI and are more likely to use AmB, has enabled the development of modified AmBs in order to reduce nephrotoxicity. Among these formulations, an extemporaneous lipid emulsion preparation of AmB (AmB/LE) is a lower cost alternative with similar benefits. Moreover, studies have shown a high prevalence of vitamin D deficiency (VDD) in immunocompromised individuals and patients hospitalized in intensive care units. Thus, vitamin D deficiency or insufficiency may hasten the progression of kidney disease and reflect on a worse prognosis in cases of acute kidney injury and drug-induced nephrotoxicity. In view of the high worldwide incidence of hypovitaminosis D, the aim of this study was to investigate whether vitamin D deficiency may induce AmB/LE-related nephrotoxicity. Wistar rats were divided into four groups: control, received a standard diet for 34 days; AmB/LE, received a standard diet for 34 days and AmB/LE (5mg/kg/day) intraperitoneally in the last 4 days; VDD, received a vitamin D-free diet for 34 days; and VDD+AmB/LE, received a vitamin D-free diet for 34 days and AmB/LE (5mg/kg/day) intraperitoneally in the last 4 days. Blood, urine and renal tissue samples were collected in order to evaluate the effects of the drug on renal function, hemodynamic and morphology. Association of AmB/LE and vitamin D deficiency led to impaired renal function, mild tubular injury, hypertension and urinary concentration defect. Hence, it is important to monitor vitamin D levels in AmB/LE treated patients, since vitamin D deficiency induces AmB/LE nephrotoxicity