Studies on the metabolism of aristolochic acids I and II

1. After oral administration of aristolochic acid I (AAI) and aristolochic acid II (AAII) to rats, the following metabolites were isolated from the urine and their structures elucidated: aristolactam I, aristolactam Ia, aristolochic acid Ia, aristolic acid I and 3, 4-methylenedioxy-8-hydroxy-1-phenanthrenecarboxylic acid (metabolites of AAI); or aristolactam Ia, aristolactam II and 3,4-methylenedioxy-1-phenanthrenecarboxylic acid (metabolites of AAII). A further metabolite of AAII having a lactam structure has not yet been isolated in pure form.

2. The metabolic pathways have been elucidated by administration of various metabolites.

3. The principal metabolite of AAI in rats was aristolactam Ia; 46% of the dose was excreted in the urine in form of this metabolite and 37% in the faeces. The other substances were minor metabolites. Those metabolites of AAII whose structures have been elucidated were minor metabolites; the largest proportion consisted of aristolactam II, which accounted for 4.6% in the urine and 8.9% in the faeces.

4. The mouse was the only animal which had the same metabolite patterns of AAI and AAII as those found in the rat. Not all the metabolites listed above were found in urine from guinea pigs, rabbits, dogs and man.     

Differential cytotoxic effects of denitroaristolochic acid II and aristolochic acids on renal epithelial cells

Aristolochic acids (AAs), naturally occurring nephrotoxins and rodent carcinogens, are commonly found in medicinal plants such as Radix aristolochiae. The toxicity of AAs is believed to be associated with the formation of promutagenic AA-DNA adducts, and it has also been suggested that the nitro group in AAs might be important in the process. In order to investigate the role of the nitro group in AA-mediated cytotoxicity, the effects of denitroaristolochic acid II (dN-AAII), aristolochic acid II (AAII) and aristolochic acid I (AAI) on renal tubular epithelial Madin–Darby canine kidney (MDCK) cells were examined and compared. The cytotoxicity of AAI, AAII and dN-AAII was found to be time- and concentration-dependent. As determined by MTT assay, AAI was found to be most toxic in MDCK cells upon exposure for 24, 48 and 72 h, followed by AAII, and dN-AAII showed the least cytotoxicity. The effect of AAI and AAII on the integrity of cell membrane was found to be similar and appeared to be more prominent than that of dN-AAII. Based on the results obtained from the flow cytometric analysis, significant apoptosis in MDCK cells was observed with AAI and AAII at as low as 25 μmol/L following exposure for 24 h, whereas significant apoptosis was induced by dN-AAII at a much higher concentration, 300 μmol/L, suggesting that both AAI and AAII were significantly more cytotoxic than dN-AAII. In addition, the levels of reactive oxygen species (ROS) were increased following treatment with AAI, AAII and dN-AAII at concentrations of 5, 25 and 25 μmol/L, respectively, for 4 h. The results suggest that the nitro group plays an important role in AA-mediated cytotoxicity in MDCK cells and increased intracellular ROS levels may be associated, at least in part, with the cell injury observed in MDCK cells.     

马兜铃酸I在大鼠体内的毒代动力学

目的采用重复多次给药毒性研究的三种剂量对马兜铃酸I进行毒代动力学的初步研究，了解在毒性实验条件下马兜铃酸I所达到的全身暴露与毒性之间的内在联系，为安全性评价和毒性机制的研究提供参考资料。方法分别灌胃给予大鼠马兜铃酸I 30、15、5mg·kg^-1，每天1次，连续14d，测定不同时间点的血浆药物浓度，用DAS药动学程序对血药浓度-时间数据进行拟合并计算毒代动力学参数。结果高、中、低三个剂量组的半衰期（t1/2）分别为（14．29±3．98）、（41．67±21．96）、（144．83±50．43）h，达峰时间（Tmax）分别为（0．10±0．06）、（0．08±0．00）、（0．08±0．00）h，峰浓度（Cmax）分别为（3．02±1．72）、（2．39±2．00）、（1．47±0．78）mg·L^-1，曲线下面积AUC（0-24）分别为（8．47±3．08）、（9．36±2．31）、（7．49±0．46）mg·L^-1·h。AUC及Cmax与剂量均不呈比例，且三种剂量的半衰期相差较远。结论马兜铃酸I能迅速吸收入血，随后浓度逐渐降低，于24h后仅存微量。在毒性剂量下，马兜铃酸I在大鼠体内的毒代动力学过程出现了一定程度的变化，具有非线性动力学性质。     

Investigation of the metabolism and reductive activation of carcinogenic aristolochic acids in rats.

The metabolic activation of aristolochic acids (AAs) that have been demonstrated to be mutagenic and carcinogenic was investigated. In vitro metabolism study indicated that AAs were metabolized to N-hydroxyaristolactam, which could be either reduced to aristolactams or rearranged to 7-hydroxyaristolactams via the Bamberger rearrangement. In vivo metabolism study is important because the intermediates (aristolactam-nitriumion) of the nitroreduction process are thought to be responsible for the carcinogenicity of AAs. Liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry (MS/MS) were applied to the analyses of a series of positional isomers of hydroxyaristolactams in rat urine samples after the in vivo study of AAs. Three hydroxylated metabolites of aristolactam II and two hydroxylated metabolites of aristolactam I were identified. The structures of the positional isomers were elucidated from the interpretation of MS/MS spectra and theoretical calculations. In addition, several new metabolites were detected in the rat urine by high-resolution mass spectrometry and MS/MS, including those from the decarboxylation of AAs and the conjugations of acetylation, glucuronidation, and sulfation of aristolochic acid Ia.     

Studies on the metabolism of aristolochic acids I and II

1. After oral administration of aristolochic acid I (AAI) and aristolochic acid II (AAII) to rats, the following metabolites were isolated from the urine and their structures elucidated: aristolactam I, aristolactam Ia, aristolochic acid Ia, aristolic acid I and 3,4-methylenedioxy-8-hydroxy-1-phenanthrenecarboxylic acid (metabolites of AAI); or aristolactam Ia, aristolactam II and 3,4-methylenedioxy-1-phenanthrenecarboxylic acid (metabolites of AAII). A further metabolite of AAII having a lactam structure has not yet been isolated in pure form. 2. The metabolic pathways have been elucidated by administration of various metabolites. 3. The principal metabolite of AAI in rats was aristolactam Ia; 46% of the dose was excreted in the urine in form of this metabolite and 37% in the faeces. The other substances were minor metabolites. Those metabolites of AAII whose structures have been elucidated were minor metabolites; the largest proportion consisted of aristolactam II, which accounted for 4.6% in the urine and 8.9% in the faeces. 4. The mouse was the only animal which had the same metabolite patterns of AAI and AAII as those found in the rat. Not all the metabolites listed above were found in urine from guinea pigs, rabbits, dogs and man.     

Comparative study of the contents of analogues of aristolochic acid in two kinds of Aristolochiae Fructus by high-performance liquid chromatography

Aristolochiae Fructus (??Madouling??) is derived from the fruits of Aristolochia contorta and A. debilis (Aristolochiaceae). These two species contain potentially nephrotoxic constituents, but are officially used in China. Distinction of constituents and toxicity between these two species remains unclear. A high-performance liquid chromatography method was developed and validated for the simultaneous determination of seven analogues of aristolochic acid (aristolochic acids I, II, IIIa, IVa and VIIa), as well as aristololactams I and II in Aristolochiae Fructus. Chromatographic separation was achieved on a Zorbax SB-C₁₈ column with a gradient mobile phase comprising acetonitrile and 1?% acetic acid?C30?mM triethylamine (20:1, v/v) buffer. Analytes were detected with a diode array detector at 250 and 260?nm. The contents of seven constituents in samples (11 batches of A. contorta fruits, 15 batches of A. debilis fruits and 33 commercial samples of Madouling) were determined. The content of aristolochic acid IVa was higher than that of aristolochic acid VIIa in A. contorta fruits, whereas the opposite was true in A. debilis fruits. This feature can be used to distinguish the two species from each other and identify the resource plant of Madouling. Through a morphological method and a newly found principle based on the ratio AA-IVa/AA-VIIa, we found that the 33 commercial samples collected from 12 provinces in China were all derived from the fruits of A. contorta.     

Cyclophilin D Promotes Acute,but Not Chronic,Kidney Injury in a Mouse Model of Aristolochic Acid Toxicity

The plant-derived toxin, aristolochic acid (AA), is the cause of Chinese Herb Nephropathy and Balkan Nephropathy. Ingestion of high dose AA induces acute kidney injury, while chronic low dose ingestion leads to progressive kidney disease. Ingested AA is taken up by tubular epithelial cells of the kidney, leading to DNA damage and cell death. Cyclophilin D (CypD) participates in mitochondrial-dependent cell death, but whether this mechanism operates in acute or chronic AA-induced kidney injury is unknown. We addressed this question by exposing CypD-/- and wild type (WT) mice to acute high dose, or chronic low dose, AA. Administration of 5 mg/kg AA to WT mice induced acute kidney injury 3 days later, characterised by loss of kidney function, tubular cell damage and death, and neutrophil infiltration. All of these parameters were significantly reduced in CypD-/- mice. Chronic low dose (2 mg/kg AA) administration in WT mice resulted in chronic kidney disease with impaired renal function and renal fibrosis by day 28. However, CypD-/- mice were not protected from AA-induced chronic kidney disease. In conclusion, CypD facilitates AA-induced acute kidney damage, but CypD does not contribute to the transition of acute kidney injury to chronic kidney disease during ongoing AA exposure.     

Pharmacokinetics of trapidil,an antagonist of platelet derived growth factor,in healthy subjects and in patients with liver cirrhosis

1Pharmacokinetic parameters of trapidil (an antagonist of platelet derived growth factor) were evaluated in 12 healthy male subjects (study I) and in a group of 10 patients with liver cirrhosis (Child B) and five control subjects, respectively (study II). 2Investigations were carried out after a single dose trapidil (200 mg) and at steady state after application of 200 mg trapidil three times daily for 5 days (study 1) or 4 days (study II). 3Study I: The concentration-time curves of the terminal elimination phase of trapidil exhibited a slight convexity which might reflect nonlinear kinetics. The AUC of trapidil obtained after the first dose (20.5 [±7.0 s.d.] μg ml⁻¹ h) was markedly higher than the AUC determined at steady state (13.2 [±3.8 s.d.] μg ml⁻¹ h), the non-parametric 90% confidence intervals of the ratio day 5/day 1 was 0.58–0.73 (point estimator 0.64). 4Study II: AUC averaged (21.4 [±9.1 s.d.] μg ml⁻¹ h) in controls and (34.4 [±14.9 s.d.] μg ml⁻¹ h) in cirrhotic patients. The 90% confidence intervals for the difference group 1 vs group 2 was 0.95–2.97 (point estimator 1.48, P=0.066). At steady state, AUC averaged (13.7 [±5.7 s.d.] μg ml⁻¹ h) in controls and (20.8 [±6.8 s.d.] μg ml⁻¹ h) in cirrhotic patients (90% confidence intervals group 1 vs group 2: 0.88–2.20 [point estimator 1.45, P=0.05]). As seen in study I, the AUC of trapidil obtained after the first dose was markedly higher than the AUC determined at steady state , the non-parametric 90% confidence intervals of the ratio day 5/day 1 was 0.48–0.84 (point estimator 0.66) in control subjects and 0.54–0.72 (point estimator 0.64) in cirrhotic patients, respectively. 5An inverse correlation was seen between the results of the monoethylglycin-xilidid (MEGX)-test and the AUC of trapidil (single dose: r=−0.516, P=0.048; steady state: r=−0.548, P=0.042). 6Results of study I and study II indicate an autoinduction of trapidil metabolism after repeated oral doses. Although trapidil elimination is decreased in patients with liver cirrhosis (study II), the elimination half-life at steady state is relatively short (2.4 [±1.1 s.d.] h) and therefore should prevent cumulation of trapidil even in cirrhotic patients.     

A CHRNA5 Smoking Risk Variant Decreases the Aversive Effects of Nicotine in Humans

Genome-wide association studies have implicated the CHRNA5-CHRNA3-CHRNB4 gene cluster in risk for heavy smoking and several smoking-related disorders. The heavy smoking risk allele might reduce the aversive effects of nicotine, but this hypothesis has not been tested in humans. We evaluated the effects of a candidate causal variant in CHRNA5, rs16969968, on the acute response to nicotine in European American (EA) and African American (AA) smokers (n=192; 50% AA; 73% male). Following overnight abstinence from nicotine, participants completed a protocol that included an intravenous (IV) dose of saline and two escalating IV doses of nicotine. The outcomes evaluated were the aversive, pleasurable, and stimulatory ratings of nicotine''s effects, cardiovascular reactivity to nicotine, withdrawal severity, and cognitive performance before and after the nicotine administration session. The heavy smoking risk allele (rs16969968*A; frequency=28% (EA) and 6% (AA)) was associated with lower ratings of aversive effects (P<5 × 10⁻⁸) with marked specificity. This effect was evident in EA and AA subjects analyzed as separate groups and was most robust at the highest nicotine dose. Rs16969968*A was also associated with greater improvement on a measure of cognitive control (Stroop Task) following nicotine administration. These findings support differential aversive response to nicotine as one likely mechanism for the association of CHRNA5-CHRNA3-CHRNB4 with heavy smoking.     

Characterization of the urinary metabolites of 5-amino-1-naphthol in the rat

The metabolic fate of [¹⁴C]5-amino-1-naphthol (5A1N) was investigated in Sprague-Dawley rats. [¹⁴C]5A1N was administered by gastric intubation to male rats at doses 1, 37 and 135 mg/kg body weight. In a separate experiment the rats were also dosed with 150 mg/kg of unlabeled 5A1N daily for 4 consecutive days. Between 74% and 85% of the administered dose was excreted in the urine. Over 98% of the urinary radioactivity was characterized as unchanged 5A1N, 5-acetamido-1-naphthol (5AA1N) and glucuronic and sulfuric acid conjugates of both 5A1N and 5AA1N. Unchanged 5A1N and 5AA1N accounted for less than 3% of the dose. The amount of 5A1N converted to 5AA1N and its conjugates varied inversely with the dose. Two minor metabolites were not identified. Rats dosed repeatedly with 150 mg/kg of 5A1N showed no significant change in metabolite excretion patterns compared to rats dosed singly. These findings indicate that in the rodent model the metabolism of 5A1N was dose dependent, and occurred predominantly by phase II reaction involving N-acetylation and conjugation with glucuronic and sulfuric acids. N-Acetylation predominated at lower doses and O-sulfate conjugation at higher doses. There was no evidence for the formation of N-hydroxylated metabolites over the dose range studied.     

Autoinduction of phase I and phase II metabolism of artemisinin in rats

1. This study was designed to get the direct evidence of the autoinduction metabolism for the antimalarial drug artemisinin (QHS). The sex effect on the pharmacokinetic profiles of QHS and its metabolites was also studied.

2. Two groups of rats received a single oral dose of QHS, and another two groups of rats were given oral doses of QHS once daily for 5 consecutive days. Plasma samples and its phase I and phase II metabolites were analysed for QHS, using a validated liquid chromatography tandem mass spectrometric (LC-MS) method.

3. Eight phase I metabolites (DQHS, M1–M7) and five phase II metabolites (M8–M12) of QHS were detected in rat plasma. The AUC_0?t of the parent drug QHS, and its phase I metabolites DQHS, M2, M3 and M6 decreased significantly (p?<?0.05) with increased oral clearance (CL/F) (p?<?0.05) after 5-day oral doses of QHS to rats. There was no change (p?>?0.05) in AUC of M1 and M4, whereas its metabolites M5 and M7 exhibited higher AUC (p?<?0.05). The AUC of phase II metabolites M8, M11 and M12 also increased after multiple oral doses of QHS. Sex difference was observed for QHS and its metabolites DQHS, M1, M3, M5, M8 and M9 in rats after a single oral dose of QHS.

4. The results gave the direct evidence for the autoinduction of both phase I and phase II metabolism of QHS. The sex effect existed for QHS.

     

A dose-dependent pharmacokinetic study on caffeic acid in rabbits after intravenous administration

The dose-dependent pharmacokinetics of caffeic acid (CA) were studied in rabbits. Three different doses (5, 10, and 25 mg kg⁻¹) were administered intravenously to six rabbits each. The concentration–time profiles for CA could be fitted by a two-compartment model for each dose. The results showed that total-body clearance and elimination rate constant from the central compartment (k₁₀) after a 5 mg kg⁻¹ dose were greater than those after the other two doses. Furthermore, the terminal elimination half-life (β half-life) and mean residence time (MRT) after a 5 mg kg⁻¹ dose were less than after the other doses. The AUC value increased linearly with dose within the range of 10–25 mg kg⁻¹. Most of the unchanged caffeic acid was excreted in the urine within 2 h. The percentage of unchanged caffeic acid excreted in the urine was 63·4, 60·0, and 55·4% after doses of 5, 10, and 25 mg kg⁻¹, respectively, which was not significantly different. However, significant differences in the renal clearances and renal excretion rate constants were observed with a 5 mg kg⁻¹ dose compared to the other doses. On the other hand, nonrenal clearances and nonrenal excretion rate constants showed no dose-related differences. The differences observed in total-body clearance, k₁₀, β half-life, and MRT between a 5 mg kg⁻¹ dose and the other doses can be explained on the basis of the differences in renal clearance and renal excretion rate constants. ©1997 John Wiley & Sons, Ltd.     

Autoinduction of phase I and phase II metabolism of artemisinin in rats

This study was designed to get the direct evidence of the autoinduction metabolism for the antimalarial drug artemisinin (QHS). The sex effect on the pharmacokinetic profiles of QHS and its metabolites was also studied. Two groups of rats received a single oral dose of QHS, and another two groups of rats were given oral doses of QHS once daily for 5 consecutive days. Plasma samples and its phase I and phase II metabolites were analysed for QHS, using a validated liquid chromatography tandem mass spectrometric (LC-MS) method. Eight phase I metabolites (DQHS, M1-M7) and five phase II metabolites (M8-M12) of QHS were detected in rat plasma. The AUC(0-t) of the parent drug QHS, and its phase I metabolites DQHS, M2, M3 and M6 decreased significantly (p < 0.05) with increased oral clearance (CL/F) (p < 0.05) after 5-day oral doses of QHS to rats. There was no change (p > 0.05) in AUC of M1 and M4, whereas its metabolites M5 and M7 exhibited higher AUC (p < 0.05). The AUC of phase II metabolites M8, M11 and M12 also increased after multiple oral doses of QHS. Sex difference was observed for QHS and its metabolites DQHS, M1, M3, M5, M8 and M9 in rats after a single oral dose of QHS. The results gave the direct evidence for the autoinduction of both phase I and phase II metabolism of QHS. The sex effect existed for QHS.     

Megadose vitamin C suppresses sulfoconjugation in human colon carcinoma cell line Caco-2

Intake of high doses of vitamin C has known to modulate sulfoconjugation of drugs in the intestine, but the underlying mechanisms for this effect remain to be elucidated. In the present study, we investigated the effects of vitamin C (l-ascorbic acid (AA)) on sulfation of 1-naphthol using Caco-2 cells, a model of human intestinal cells. We found that high dose of AA inhibited the accumulation of 1-naphthyl sulfate in Caco-2 culture medium within 24 h in a dose-dependent manner (IC₅₀ = 42 mM). Dehydroascorbic acid (DA), an oxidized form of AA, showed no inhibition. AA did not inhibit the in vitro sulfotransferase (SULT) activity toward 1-naphthol, whereas it reduced the expression of genes belonging to SULT1A family, SULT1A1 and SULT1A3. DA showed no effect on SULT1A gene expression. Consistent with the reduction in gene expression, AA reduced the cytosolic SULT activity towards 1-naphthol in the AA-treated Caco-2 cells. In addition, cAMP exerted an additive effect on AA-mediated repression of SULT1A gene expression. Our results suggest that megadose AA suppresses sulfoconjugation in the intestine mainly by downregulating the expression of SULT1A genes.     

Erythropoietin inhibits liver gelatinases during galactosamine-induced hepatic damage in rats

Matrix metalloproteinase (MMP)-2 and -9 (gelatinases) participate in extracellular protein remodeling. Moreover, they are involved in the development of hepatic fibrosis. The goal of this study was to evaluate liver gelatinase activities after erythropoietin (Epo) treatment (1U/dose, sc) in experimentally damaged livers of rats treated with D-galactosamine (Gal, 800 mg/kg/dose, ip).Sixty rats were divided into six equal groups: I – received 5 doses of Epo anda single dose of Gal [the experiment duration (ED): 10 days]; II – received 5 doses of Epo and 3 doses of Gal (ED: 14 days); III – received only 5 doses of Epo (ED: 9 days); IV – received 3 doses of Gal (ED: 5 days); V–received a single dose of Gal (ED: 1 day); VI – control group (ED: 9 days). The animals were sacrificed and the livers were collected 48 h after the last drug administration. The activity of gelatinases was measured using gelatin zymography. No fluctuations in gelatinase activities were observed after the administration of a single dose of Gal in comparison to the control group. However, a significant increase in gelatinase activities was observed after treatment with three doses of Gal. Five doses of Epo administrated before Gal treatment prevented elevated gelatinase activities: MMP-9 activity was comparable to control, and MMP-2 activity was decreased (group II). The gelatinase activities was lower in group I and II in comparison to the control group. These results revealed that Epo decreases MMP-2 and MMP-9 activity, suggesting that it is a hepatoprotective agent against hepatic damage induced by galactosamine injection.     

Pyrazine diazohydroxide (NSC-361456)

Summary Pyrazine diazohydroxide (NSC-361456) was identified as an active congener of pyridine 2-diazohydroxide with enhanced stability under physiologic conditions. In this phase I study, 35 patients with advanced cancer received 62 courses of PZDH administered intravenously every 3 weeks at doses ranging from 15–608 mg/m². The dose-limiting toxicity was myelosuppression and the maximal tolerated dose was 487 mg/m². Hematologie toxicity was delayed and prolonged with median time to recovery about 5 weeks. Mild gastrointestinal toxicity in the form of nausea and vomiting was fairly common. Ondansetron was effective in reducing nausea and vomiting at higher dose levels. Other less common reactions included stomatitis, diarrhea, fatigue, alopecia, and mild abnormalities of renal function and hepatic enzymes. PZDH pharmacokinetics were characterized in 16 patients who received doses of 100–608 mg/m². Plasma elimination was fit to one (12/16) or two (4/16) compartment model with a mean k₁₀ half-life of 11.5 min. Clearance was dose dependent. Hematologic toxicity was related to PZDH dose, AUC and peak plasma concentration. The sigmoidal relationships between hematologic toxicity and AUC or peak plasma concentration were well described by the Hill equation. There were no objective responses observed in this study. Based on this study, the recommended dose for phase II evaluation of PZDH using this schedule is 390 mg/m².     

Subchronic toxicity studies of the aqueous extract of Aristolochiae fructus in Sprague-Dawley rats

The subchronic toxicity of Aristolochiae fructus containing aristolochic acids (AAs), a natural component in the Aristolochiaceae family, was investigated. The A. fructus was daily administered by gavage to male and female rats for 90 d at dose levels of 21.35, 213.5, and 2135 mg/kg (equivalent to 0.05, 0.5, and 5 mg/kg as AAs, respectively). During the test period, clinical signs, mortality, body weights, food and water consumption, hematology, serum biochemistry, organ weights, and histopathology were examined. Significant decreases in body weight gain were noted in the high-dose group receiving both the aqueous extract of A. fructus and AAs. Decreases in food consumption were noted beginning at 50 d and did not recover in the high-dose group of aqueous extract of A. fructus and AAs. Irrespective of dose, water consumption was not affected. There was no mortality or adverse clinical signs, hematology, or serum biochemistry in the treatment groups versus control. Nephrotoxicity and hyperplasia of epithelial cells in the forestomach were observed in rats receiving the highest dose of aqueous extract of A. fructus and at doses of >or= 0.5 mg/kg/day AAs. For both genders, the no-observed-adverse-effect level (NOAEL) for A. fructus based on this subchronic study in rats was considered to be 21.3 mg/kg/d.     

Nephroprotective Role of Resveratrol and Ursolic Acid in Aristolochic Acid Intoxicated Zebrafish

The nephrotoxicity of aristolochic acid (AA) is well known, but information regarding the attenuation of AA-induced toxicity is limited. The aim of the present study was to study the nephroprotective effects of resveratrol (Resv) and ursolic acid (UA) in a zebrafish model. We used two transgenic lines, Tg(wt1b:EGFP) and Tg(gata1:DsRed), to evaluate the nephroprotective effects of Resv and UA by recording subtle changes in the kidney and red blood cell circulation. Our results demonstrated that both Resv and UA treatment can attenuate AA-induced kidney malformations and improve blood circulation. Glomerular filtration rate assays revealed that both Resv and UA treatment can restore renal function (100% for Mock; 56.1% ± 17.3% for AA-treated; 80.2% ± 11.3% for Resv+AA; and 83.1% ± 8.1% for UA+AA, n = 15). Furthermore, real-time RT-PCR experiments showed that pre-treatment with either Resv or UA suppresses expression of pro-inflammatory genes. In conclusion, our findings reveal that AA-induced nephrotoxicities can be attenuated by pre-treatment with either Resv or UA. Therefore, we believe that zebrafish represent an efficient model for screening AA-protective natural compounds.     

Phase Ι trial of weekly Docetaxel and daily Temozolomide in patients with metastatic disease

Summary  Docetaxel is second generation taxoid that has shown activity against a variety of cancers and has been approved for use in cancers of the breast, lung, head and neck, ovaries and prostate. Temozolomide is an alkylating agent which crosses the blood brain barrier and has demonstrated antitumor activity against a broad range of tumor types, including malignant glioma, melanoma, non small cell lung cancer and carcinoma of the ovary and colon. A Phase I trial was conducted to determine the toxicity of this combination in refractory solid tumor patients. Methods: Twenty five patients with metastatic cancers were enrolled in a Phase I dose escalation trial. Docetaxel was administered weekly in 5 escalating doses of 25 to 35 mg/ m² as a one-hour bolus intravenous infusion for 3 consecutive weeks. Temozolamide was administered orally daily for 3 weeks (escalating doses of 75 to 100 mg/m²). Cycles were repeated at 4 week intervals. Results: The maximum tolerated dose (MTD) was not determined in this study. The most commonly reported adverse events were mild to moderate nausea, vomiting and fatigue. Thrombocytopenia was the most commonly observed grade 3 and 4 hematological toxicity. Eight patients had dose interruptions for adverse events and only one patient had a dose reduction while receiving 30 mg/ m² of docetaxel and 90 mg/ m² of temozolomide due to grade 3 thrombocytopenia. Two patients achieved partial responses and 88% of the patients are deceased. The median survival is 8.4 months. Conclusions: The combination of docetaxel and temozolomide was well tolerated and these agents can be safely combined. For phase II trials, docetaxel 35 mg/ m² IV day 1, 8 and 15, and daily temozolomide at 100 mg/ m² day 1–21 are recommended. Supported by grants from Schering Plough and Sanofi-Aventis