Drug Metabolism Letters - Volume 1, Issue 4, 2007

We investigated the effects of Cymbopogon schoenanthus herb on experimental induced kidney stones in male Wistar albino rats. Oxalate nephrotoxicity was experimentally induced by 200 mg single dose of glycolic acid given orally (gavage). Rats were divided into three groups, glycolic acid, glycolic acid plus Cymbopogon schoenanthus, and control (D. water). Urine analysis of blood urea nitrogen (BUN), creatinin Read More

The roles of alkylation and redox cycling in quinone toxicity were investigated. In general the more cytotoxic quinones produced the highest responses in an assay monitoring redox activity. No evidence of alkylation of high molecular weight protein thiols was detected. We conclude quinone toxicity is dominated by redox cycling.

Acute lung injury is accompanied by an increased endothelial chemokine production and adhesion molecule expression, which may result in an extensive neutrophil infiltration. Moreover, a destruction of the alveolar epithelium and capillary endothelium may result in permeability edema. As such, the search for novel anti-inflammatory substances, able to downregulate these parameters as well as the tissue damage holds the Read More

Sera from AIH (autoimmune hepatitis) type 2 patients contain an autoantibody against the UGT1A subtype, called anti-LKM3. Previously, we reported that sera in AIH type 1 patients contained autoantibodies against drugmetabolizing enzymes (Shinoda et al. (2004) Autoimmunity, 37, 473). In this report, we showed that AIH-1 sera did not react with some peptides in the C-terminal half of the UGT1A subtype but reacted Read More

Background: Sirolimus is the latest immunosuppressive agent used to prevent rejection, and may have less nephrotoxicity than calcineurin inhibitor (CNI)-based regimens. To date there has been little documentation of clinically significant proteinuria linked with the use of sirolimus. We have encountered several patients who developed substantial proteinuria associated with sirolimus use. In each patient, the close temporal a Read More

Our policy of conducting biotransformation studies with extended chromatography prior to pharmacokinetic bioanalyses allowed us to quickly detect an unusual, cis/trans metabolite in rat plasma that was inseparable using a short chromatographic method. We caution investigators that short methods invite unknown isobaric metabolites to cause inaccuracies in plasma concentration measurements.

Epidemiological studies have identified a number of risk factors that contribute to the development of cervical cancer precursors and cervical cancer. These include infection with certain oncogenic types of human papillomaviruses (HPVs) and other socio-economic factors. Tobacco smoking is an independent risk-factor for cervical neoplasia. It has been found that polymorphism at loci that encode carcinogen-metabolizing en Read More

Cytochrome P450 isoforms from male rat liver microsomes were comprehensively identified using nano liquid chromatography tandem mass spectrometry (nanoLC-MS/MS). The enrichment of P450, an endomembrane-anchored heme protein, was achieved by solubility-based protein fractionation, and greatly improved the total number of identified P450 isoforms. LC-MS/MS analysis of fractions resulted in the identific Read More

This study describes the application of the mass defect filter method for the detection of two unpredicted oxazole- ring opened metabolites of muraglitazar in the feces of humans following oral administration. Unlike other muraglitazar metabolites, these metabolites formed little to no protonated ions, and the NH4 + or Na+ adduct ions that were formed were weak and not discernible from fecal interferences even afte Read More

An LC-MS/MS-based approach that employs authentic radioactive metabolites as reference standards was developed to estimate metabolite exposures in early drug development studies. This method is useful to estimate metabolite levels in studies done with non-radiolabeled compounds where metabolite standards are not available to allow standard LC-MS/MS assay development. A metabolite mixture obtained from an in Read More

Leflunomide was found to be metabolized predominantly to A77-1726 and two novel hydroxylated metabolites, M1 and M2, in microsomes while A77-1726 was only biotransformed to M1. M1 and M2 were proposed to be the hydroxylated α-cyanoenol form of A77-1726 and the hydroxylated 5 methyl-isoxazole form of leflunomide, respectively.

We have developed an easy and sensitive method to measure P-glycoprotein (P-gp) activity using [γ-32P]ATP and charcoal. This method utilizes the nature of adsorption of organic phosphate to charcoal. The standard assay method is as follows: the reaction mixture (20 μl) of 1 mM [γ-32P]ATP (1 Ci/mol), 2.5 μg P-gp membranes, and the drug was incubated for 30 min, and 50 μl of 10% charcoal suspension in 0.1 M phosphate buff Read More

We used 2,3,8,9-tetrachlorodibenzo-p-dioxin (TCDD) and dexamethasone (DEX) to examine their effects on aryl hydrocarbon receptor (AhR) and glucocorticoid receptor (GR) in HeLa cells. TCDD (5 nM), DEX (100 nM) and their combination down-regulated GR after 24 h. DEX reversed AhR mRNA increase and AhR protein decrease caused by TCDD. Since AhR-GR cross-talk occurs in cell-type and species-specific manner, the Read More