Inter-species differences between humans and other mammals in the in vitro metabolism of carbofuran and the role of human CYP enzymes.

This study investigated the metabolic transformation of carbofuran in seven species of mammals using LC-MS/MS and liver microsomes. The results revealed species-specific differences in metabolite formation, indicating the potential role of metabolic pathways in toxicity and risk assessment. The majority of carbofuran was metabolized through the 3-hydroxycarbofuran pathway, with the highest levels observed in dogLM and the lowest in humanLM.

Metabolic profiling and - extrapolation of furathiocarb in mammalian hepatic microsomes.

Furathiocarb is a carbamate insecticide found in marine ecosystems as well as river water and sediments. The aim of this study was to characterize species differences in the metabolism of furathiocarb in seven mammalian species (human, monkey, minipig, rat, mouse, dog, rabbit) analyzed by LC-TOF-MS/MS, in order to provide qualitative and quantitative chemical-specific data to enhance toxicological risk assessment. Furathiocarb was mainly biotransformed to carbofuran metabolic pathway (N-S) bond-cleavage.

Characterization of furathiocarb metabolism in in-vitro human liver microsomes and recombinant cytochrome P450 enzymes.

Furathiocarb is a carbamate insecticide detected in ecosystems. Its main metabolite carbofuran has been alluded to affect birth outcomes and disturb hormone levels in humans. The metabolism of furathiocarb in humans has not been characterized.

Genetically Modified Caco-2 Cells With Improved Cytochrome P450 Metabolic Capacity.

The human intestinal Caco-2 cell line has been extensively used as a model of small intestinal absorption but it lacks expression and function of cytochrome P450 enzymes, particularly CYP3A4 and CYP2C9, which are normally expressed in the intestinal epithelium. In order to increase the expression and activity of CYP isozymes in these cells, we created 2 novel Caco-2 sublines expressing chimeric constitutive androstane or pregnane X receptors and characterized these cells for their metabolic and absorption properties. In spite of elevated mRNA expression of transporters and differentiation markers, the permeation properties of the modified cell lines did not significantly differ from those of the wild-type cells.

Human variation and CYP enzyme contribution in benfuracarb metabolism in human in vitro hepatic models.

Human responses to the toxicological effects of chemicals are often complicated by a substantial interindividual variability in toxicokinetics, of which metabolism is often the most important factor. Therefore, we investigated human variation and the contributions of human-CYP isoforms to in vitro metabolism of benfuracarb. The primary metabolic pathways were the initial sulfur oxidation to benfuracarb-sulfoxide and the nitrogen-sulfur bond cleavage to carbofuran (activation).

Comparative metabolism of benfuracarb in in vitro mammalian hepatic microsomes model and its implications for chemical risk assessment.

In vitro metabolism of benfuracarb in liver microsomes from seven species was studied in order to quantitate species-specific metabolic profiles and enhance benfuracarb risk assessment by interspecies comparisons. Using LC-MS/MS, a total of seven phase-I-metabolites were detected from the extracted chromatograms and six of them were unequivocally identified. Benfuracarb was metabolized via two metabolic pathways, the sulfur oxidation pathway and nitrogen sulfur bond cleavage, yielding carbofuran, which metabolized further.

Characterization of human cytochrome P450 induction by pesticides.

Pesticides are a large group of structurally diverse toxic chemicals. The toxicity may be modified by cytochrome P450 (CYP) enzyme activity. In the current study, we have investigated effects and mechanisms of 24 structurally varying pesticides on human CYP expression.

Exposure to oral S-ketamine is unaffected by itraconazole but greatly increased by ticlopidine.

This study examined drug-drug interactions of oral S-ketamine with the cytochrome P450 (CYP) 2B6 inhibitor ticlopidine and the CYP3A inhibitor itraconazole. In this randomized, blinded, crossover study, 11 healthy volunteers ingested 0.2 mg/kg S-ketamine after pretreatments with oral ticlopidine (250 mg twice daily), itraconazole (200 mg once daily), or placebo in 6-day treatment periods at intervals of 4 weeks.

Metabolism of α-thujone in human hepatic preparations in vitro.

This study aims to characterize the metabolism of α-thujone in human liver preparations in vitro and to identify the role of cytochrome P450 (CYP) and possibly other enzymes catalyzing α-thujone biotransformations. With a liquid chromatography-mass spectrometry (LC-MS) method developed for measuring α-thujone and four potential metabolites, it was demonstrated that human liver microsomes produced two major (7- and 4-hydroxy-thujone) and two minor (2-hydroxy-thujone and carvacrol) metabolites. Glutathione and cysteine conjugates were detected in human liver homogenates, but not quantified.

Metabolism of carbosulfan II. Human interindividual variability in its in vitro hepatic biotransformation and the identification of the cytochrome P450 isoforms involved.

This study aims to characterize interindividual variability and individual CYP enzymes involved in the in vitro metabolism of the carbamate insecticide carbosulfan. Microsomes from ten human livers (HLM) were used to characterize the interindividual variability in carbosulfan activation. Altogether eight phase I metabolites were analyzed by LC-MS.

Metabolism of carbosulfan. I. Species differences in the in vitro biotransformation by mammalian hepatic microsomes including human.

The in vitro metabolism of carbosulfan, a widely used carbamate insecticide, by hepatic microsomes from human, rat, mouse, dog, rabbit, minipig, and monkey was studied. Altogether eight (8) phase I metabolites were detected by LC-MS; phase II metabolites were not found in human homogenates fortified with appropriate cofactors. The primary metabolic pathways were the initial oxidation of sulfur to carbosulfan sulfinamide ('sulfur oxidation pathway') and the cleavage of the nitrogen sulfur bond (N-S) to give carbofuran and dibutylamine ('carbofuran pathway').

Characterization of diuron N-demethylation by mammalian hepatic microsomes and cDNA-expressed human cytochrome P450 enzymes.

Diuron, a widely used herbicide and antifouling biocide, has been shown to persist in the environment and contaminate drinking water. It has been characterized as a "known/likely" human carcinogen. Whereas its environmental transformation and toxicity have been extensively examined, its metabolic characteristics in mammalian livers have not been reported.

Effect of renal impairment on the pharmacokinetics of bupropion and its metabolites.

Aims: To investigate the effect of kidney disease on bupropion pharmacokinetics and on cytochrome P450 (CYP) 2B6 activity as measured by bupropion hydroxylation.

Methods: In an open parallel group study, 17 healthy, nonsmoking subjects and 10 patients with impaired kidney function received a single 150 mg oral dose of sustained release bupropion. Plasma concentrations of bupropion and its metabolites were measured for up to 72 h.

In vitro metabolism and interactions of the fungicide metalaxyl in human liver preparations.

In order to provide additional information for risk assessment of the fungicide metalaxyl, the main objectives were (1) to elucidate the interactions of metalaxyl with different human liver cytochrome P450 enzymes, (2) to tentitatively identify and (semi)quantify metabolites in vitro and (3) to identify human CYP enzymes responsible for metabolism. The mean inhibitory concentrations (IC(50)) for 7-pentoxyresorufin-O-dealkylation (CYP2B) and bupropion hydroxylation (2B6) were 48.9 and 41.

Incisional and epidural analgesia after caesarean delivery: a prospective, placebo-controlled, randomised clinical study.

Background: This study evaluated efficacy, safety and patient satisfaction with incisional analgesia with a subfascial catheter compared to epidural analgesia for pain relief following caesarean section.

Methods: Forty patients were randomised after elective caesarean section to receive either intermittent 10-mL boluses of 0.125% levobupivacaine into the epidural space and physiologic saline into the surgical wound or intermittent 10-mL boluses of 0.

Monoclonal antibodies to human nephrin.

Nephrin is a 180-200-kDa transmembrane protein of the immunoglobulin superfamily. In the kidney, nephrin localizes to the slit diaphragm (SD) between interdigitating podocyte foot processes and mutations in the nephrin gene cause congenital nephrotic syndrome. In addition to this rare genetic disorder, recent reports indicate that nephrin is more generally involved in the pathogenesis of glomerular disease.

Clustering-induced tyrosine phosphorylation of nephrin by Src family kinases.

Background: Nephrin is a recently discovered protein of the immunoglobulin (Ig) superfamily. In the kidney, it is located at the slit diaphragm, which forms the decisive size-selective filter of glomerular ultrafiltration barrier and locates between the interdigitating foot processes of podocytes. Nephrin is mutated in congenital nephrosis of the Finnish type (NPHS1) and has been demonstrated to be an essential component of the slit diaphragm.

Recurrence of nephrotic syndrome in kidney grafts of patients with congenital nephrotic syndrome of the Finnish type: role of nephrin.

Background: Congenital nephrotic syndrome of the Finnish type (CNF, NPHS1) is caused by mutations in the NPHS1 gene. NPHS1 codes for nephrin, a cell adhesion protein located at the glomerular slit diaphragm. Renal transplantation is the only treatment option for most patients with NPHS1.

Nephrin redistribution on podocytes is a potential mechanism for proteinuria in patients with primary acquired nephrotic syndrome.

We investigated the distribution of nephrin by immunofluorescence microscopy in renal biopsies of patients with nephrotic syndrome: 13 with membranous glomerulonephritis (GN), 10 with minimal change GN, and seven with focal segmental glomerulosclerosis. As control, six patients with IgA GN without nephrotic syndrome and 10 normal controls were studied. We found an extensive loss of staining for nephrin and a shift from a podocyte-staining pattern to a granular pattern in patients with nephrotic syndrome, irrespective of the primary disease.

Role of nephrin in cell junction formation in human nephrogenesis.

Nephrin is a cell adhesion protein located at the slit diaphragm area of glomerular podocytes. Mutations in nephrin-coding gene (NPHS1) cause congenital nephrotic syndrome (NPHS1). We studied the developmental expression of nephrin, ZO-1 and P-cadherin in normal fetal kidneys and in NPHS1 kidneys.

Timp-1, -2 and -3 show coexpression with gelatinases A and B during mouse tooth morphogenesis.

Matrix metalloproteinases (MMPs) have been implicated in tissue remodelling and in regulation of cell-matrix interactions during organ development. The activity of MMPs is regulated by members of the TIMP (tissue inhibitors of metalloproteinase) family. We analyzed by in situ hybridization the expression of gelatinase A (MMP-2) and gelatinase B (MMP-9) as well as Timp-1, -2 and -3 during different stages of mouse tooth development.

Murine matrix metalloproteinase 9 gene. 5'-upstream region contains cis-acting elements for expression in osteoclasts and migrating keratinocytes in transgenic mice.

Knowledge about the regulation of cell lineage-specific expression of extracellular matrix metalloproteinases is limited. In the present work, the murine matrix metalloproteinase 9 (MMP-9) gene was shown to contain 13 exons, and the 2.8-kilobase pair upstream region was found to contain several common promoter elements including a TATA box-like motif, three GC boxes, four AP-1-like binding sites, an AP-2 site, and three PEA3 consensus sequences that may be important for basic activity of the gene.

92-kDa type IV collagenase and TIMP-3, but not 72-kDa type IV collagenase or TIMP-1 or TIMP-2, are highly expressed during mouse embryo implantation.

Expression of 72 kDa and 92 kDa type IV collagenases and the metalloproteinase inhibitors TIMPs 1, 2, and 3 was studied by in situ hybridization in implanting mouse embryos of days 5.5 to 7.5.

Assessment of 72-kilodalton gelatinase and TIMP-1 gene expression in normal and sclerotic murine glomeruli.

Mice transgenic for bovine growth hormone (bGH) develop progressive diffuse glomerulosclerosis. Because murine mesangial cells in vitro were found to express the genes for 72-kd gelatinase and the metalloproteinase inhibitor TIMP-1, the expression of these genes in vivo in isolated whole glomeruli from bGH mice and normal control littermates was examined. Intact glomeruli were isolated by microdissection and subjected to reverse transcription.