Colchicine anti-inflammatory therapy for non-intensive care unit hospitalized COVID-19 patients: results from a pilot open-label, randomized controlled clinical trial.

Systemic inflammation is a hallmark of severe coronavirus disease-19 (COVID-19). Anti-inflammatory therapy is considered crucial to modulate the hyperinflammatory response (cytokine storm) in hospitalized COVID-19 patients. There is currently no specific, conclusively proven, cost-efficient, and worldwide available anti-inflammatory therapy available to treat COVID-19 patients with cytokine storm. The present study aimed to investigate the treatment benefit of oral colchicine for hospitalized COVID-19 patients with suspected cytokine storm. Colchicine is an approved drug and possesses multiple anti-inflammatory mechanisms. This was a pilot, open-label randomized controlled clinical trial comparing standard of care (SOC) plus oral colchicine (colchicine arm) vs. SOC alone (control arm) in non-ICU hospitalized COVID-19 patients with suspected cytokine storm. Colchicine treatment was initiated within first 48 hours of admission delivered at 1.5 mg loading dose, followed by 0.5 mg b.i.d. for next 6 days and 0.5 mg q.d. for the second week. A total of 96 patients were randomly allocated to the colchicine (n=48) and control groups (n=48). Both colchicine and control group patients experienced similar clinical outcomes by day 14 of hospitalization. Treatment outcome by day 14 in colchicine vs control arm: recovered and discharged alive: 36 (75.0%) vs. 37 (77.1%), remain admitted after 14-days: 4 (8.3%) vs. 5 (10.4%), ICU transferred: 4 (8.3%) vs. 3 (6.3%), and mortality: 4 (8.3%) vs. 3 (6.3%). The speed of improvement of COVID-19 acute symptoms including shortness of breath, fever, cough, the need of supplementary oxygen, and oxygen saturation level, was almost identical in the two groups. Length of hospitalization was on average 1.5 day shorter in the colchicine group. There was no evidence for a difference between the two groups in the follow-up serum levels of inflammatory biomarkers including C-reactive protein (CRP), D-dimer, lactate dehydrogenase (LDH), ferritin, interleukin-6 (IL-6), high-sensitivity troponin T (hs-TnT) and N-terminal pro b-type natriuretic peptide (NT pro-BNP). According to the results of our study, oral colchicine does not appear to show clinical benefits in non-ICU hospitalized COVID-19 patients with suspected cytokine storm. It is possible that the anti-inflammatory pathways of colchicine are not crucially involved in the pathogenesis of COVID-19.

Prevalence and determinants of stunting among preschool and school-going children in the flood-affected areas of Pakistan / Prevalência e determinantes da baixa estatura entre crianças em idade pré-escolar e em idade escolar nas áreas afetadas pelas enchentes do Paquistão

Stunting is a significant public health problem in low- and middle-income countries. This study assessed the prevalence of stunting and associated risk factors of stunting among preschool and school-going children in flood-affected areas of Pakistan. A cross-sectional study was conducted by visiting 656 households through multi-stage sampling. Respondent's anthropometric measurements, socio-demographic information and sanitation facilities were explored. A logistic regression model was used to determine determinants of stunting, controlling for all possible confounders. The overall prevalence of stunting in children was 40.5%, among children 36.1% boys and 46.3% of girls were stunted. The prevalence of stunting in under-five children was 50.7%. Female children (OR=1.35, 95% CI:0.94-2.0), children aged 13-24 months (OR=6.5, 95% CI: 3.0-13.9), mothers aged 15-24 years (OR=4.4, 95% CI: 2.6-7.2), joint family (OR=2.1, 95% CI: 1.4-3.0) did not have access to improved drinking water (OR=3.3, 95% CI: 1.9-5.9), and the toilet facility (OR=2.8, 95% CI, 1.9-4.3), while the children from district Nowshera (OR=1.7, 95% CI: 0.9-3.2) were significantly (P<0.05) associated in univariate analysis. The regression model revealed that child age, maternal age, family type, quality of water, and toilet facility, were the significant (P<0.05) factors contributing to child stunting in the flood-hit areas. Identification of key factors might be helpful for policymakers in designing comprehensive community-based programs for the reduction of stunting in flood-affected areas. In disasters such as flood, the detrimental consequences of the stunting problem could be even more on children. Evidence-based education and care must be provided to the families in the flood-affected regions to reduce the stunting problem. The determinants of stunting should be targeted by making comprehensive policies regarding proper nutrition, livelihood, clean water, and sanitation facilities in flood-hit regions.

A baixa estatura é um problema significativo de saúde pública em países de baixa e média renda. Este estudo avaliou a prevalência de nanismo e os fatores de risco associados de nanismo entre crianças em idade pré-escolar e em idade escolar em áreas afetadas por inundações do Paquistão. Foi realizado um estudo transversal visitando 656 domicílios por meio de amostragem em múltiplos estágios. As medidas antropométricas do entrevistado, informações sociodemográficas e instalações de saneamento foram exploradas. Um modelo de regressão logística foi usado para determinar os determinantes do nanismo, controlando todos os possíveis fatores de confusão. A prevalência geral de baixa estatura em crianças foi de 40,5%, entre as crianças 36,1% dos meninos e 46,3% das meninas com baixa estatura. A prevalência de baixa estatura em crianças menores de 5 anos foi de 50,7%. Crianças do sexo feminino (OR = 1,35, IC de 95%: 0,94-2,0), crianças de 13-24 meses (OR = 6,5, IC de 95%: 3,0-13,9), mães de 15-24 anos (OR = 4,4, IC de 95%: 2,6-7,2), família conjunta (OR = 2,1, IC 95%: 1,4-3,0) não tiveram acesso a água potável de qualidade (OR = 3,3, IC 95%: 1,9-5,9) e a banheiro (OR = 2,8, IC de 95%, 1,9-4,3), enquanto as crianças do distrito de Nowshera (OR = 1,7, IC de 95%: 0,9-3,2) foram significativamente (P < 0,05) associadas na análise univariada. O modelo de regressão revelou que a idade da criança, idade materna, tipo de família, qualidade da água e banheiro foram os fatores significativos (P < 0,05) que contribuíram para a baixa estatura infantil nas áreas afetadas pelas enchentes. A identificação de fatores-chave pode ser útil para os formuladores de políticas no planejamento de programas comunitários abrangentes para a redução da baixa estatura em áreas afetadas pelas enchentes. Em desastres como enchentes, as consequências prejudiciais do problema de baixa estatura podem ser ainda maiores para as crianças. Educação baseada em evidências e cuidados deve ser fornecida às famílias nas regiões afetadas pelas enchentes para reduzir o problema de nanismo. Os determinantes do retardo de crescimento devem ser almejados pela formulação de políticas abrangentes sobre nutrição adequada, meios de subsistência, água potável e instalações de saneamento nas regiões afetadas pelas enchentes.

Prevalence and determinants of stunting among preschool and school-going children in the flood-affected areas of Pakistan / Prevalência e determinantes da baixa estatura entre crianças em idade pré escolar e em idade escolar nas áreas afetadas pelas enchentes do Paquistão

Stunting is a significant public health problem in low- and middle-income countries. This study assessed the prevalence of stunting and associated risk factors of stunting among preschool and school-going children in flood-affected areas of Pakistan. A cross-sectional study was conducted by visiting 656 households through multi-stage sampling. Respondent's anthropometric measurements, socio-demographic information and sanitation facilities were explored. A logistic regression model was used to determine determinants of stunting, controlling for all possible confounders. The overall prevalence of stunting in children was 40.5%, among children 36.1% boys and 46.3% of girls were stunted. The prevalence of stunting in under-five children was 50.7%. Female children (OR=1.35, 95% CI:0.94-2.0), children aged 13-24 months (OR=6.5, 95% CI: 3.0-13.9), mothers aged 15-24 years (OR=4.4, 95% CI: 2.6-7.2), joint family (OR=2.1, 95% CI: 1.4-3.0) did not have access to improved drinking water (OR=3.3, 95% CI: 1.9-5.9), and the toilet facility (OR=2.8, 95% CI, 1.9-4.3), while the children from district Nowshera (OR=1.7, 95% CI: 0.9-3.2) were significantly (P<0.05) associated in univariate analysis. The regression model revealed that child age, maternal age, family type, quality of water, and toilet facility, were the significant (P<0.05) factors contributing to child stunting in the flood-hit areas. Identification of key factors might be helpful for policymakers in designing comprehensive community-based programs for the reduction of stunting in flood-affected areas. In disasters such as flood, the detrimental consequences of the stunting problem could be even more on children. Evidence-based education and care must be provided to the families in the flood-affected regions to reduce the stunting problem. The determinants of stunting should [...].

A baixa estatura é um problema significativo de saúde pública em países de baixa e média renda. Este estudo avaliou a prevalência de nanismo e os fatores de risco associados de nanismo entre crianças em idade pré-escolar e em idade escolar em áreas afetadas por inundações do Paquistão. Foi realizado um estudo transversal visitando 656 domicílios por meio de amostragem em múltiplos estágios. As medidas antropométricas do entrevistado, informações sociodemográficas e instalações de saneamento foram exploradas. Um modelo de regressão logística foi usado para determinar os determinantes do nanismo, controlando todos os possíveis fatores de confusão. A prevalência geral de baixa estatura em crianças foi de 40,5%, entre as crianças 36,1% dos meninos e 46,3% das meninas com baixa estatura. A prevalência de baixa estatura em crianças menores de 5 anos foi de 50,7%. Crianças do sexo feminino (OR = 1,35, IC de 95%: 0,94-2,0), crianças de 13-24 meses (OR = 6,5, IC de 95%: 3,0-13,9), mães de 15-24 anos (OR = 4,4, IC de 95%: 2,6-7,2), família conjunta (OR = 2,1, IC 95%: 1,4-3,0) não tiveram acesso a água potável de qualidade (OR = 3,3, IC 95%: 1,9-5,9) e a banheiro (OR = 2,8, IC de 95%, 1,9-4,3), enquanto as crianças do distrito de Nowshera (OR = 1,7, IC de 95%: 0,9-3,2) foram significativamente (P < 0,05) associadas na análise univariada. O modelo de regressão revelou que a idade da criança, idade materna, tipo de família, qualidade da água e banheiro foram os fatores significativos (P < 0,05) que contribuíram para a baixa estatura infantil nas áreas afetadas pelas enchentes. A identificação de fatores-chave pode ser útil para os formuladores de políticas no planejamento de programas comunitários abrangentes para a redução da baixa estatura em áreas afetadas pelas enchentes. Em desastres como enchentes, as consequências prejudiciais do problema de baixa estatura podem [...].

Prevalence and determinants of stunting among preschool and school-going children in the flood-affected areas of Pakistan

Abstract Stunting is a significant public health problem in low- and middle-income countries. This study assessed the prevalence of stunting and associated risk factors of stunting among preschool and school-going children in flood-affected areas of Pakistan. A cross-sectional study was conducted by visiting 656 households through multi-stage sampling. Respondents anthropometric measurements, socio-demographic information and sanitation facilities were explored. A logistic regression model was used to determine determinants of stunting, controlling for all possible confounders. The overall prevalence of stunting in children was 40.5%, among children 36.1% boys and 46.3% of girls were stunted. The prevalence of stunting in under-five children was 50.7%. Female children (OR=1.35, 95% CI:0.94-2.0), children aged 13-24 months (OR=6.5, 95% CI: 3.0-13.9), mothers aged 15-24 years (OR=4.4, 95% CI: 2.6-7.2), joint family (OR=2.1, 95% CI: 1.4-3.0) did not have access to improved drinking water (OR=3.3, 95% CI: 1.9-5.9), and the toilet facility (OR=2.8, 95% CI, 1.9-4.3), while the children from district Nowshera (OR=1.7, 95% CI: 0.9-3.2) were significantly (P 0.05) associated in univariate analysis. The regression model revealed that child age, maternal age, family type, quality of water, and toilet facility, were the significant (P 0.05) factors contributing to child stunting in the flood-hit areas. Identification of key factors might be helpful for policymakers in designing comprehensive community-based programs for the reduction of stunting in flood-affected areas. In disasters such as flood, the detrimental consequences of the stunting problem could be even more on children. Evidence-based education and care must be provided to the families in the flood-affected regions to reduce the stunting problem. The determinants of stunting should be targeted by making comprehensive policies regarding proper nutrition, livelihood, clean water, and sanitation facilities in flood-hit regions.

Resumo A baixa estatura é um problema significativo de saúde pública em países de baixa e média renda. Este estudo avaliou a prevalência de nanismo e os fatores de risco associados de nanismo entre crianças em idade pré-escolar e em idade escolar em áreas afetadas por inundações do Paquistão. Foi realizado um estudo transversal visitando 656 domicílios por meio de amostragem em múltiplos estágios. As medidas antropométricas do entrevistado, informações sociodemográficas e instalações de saneamento foram exploradas. Um modelo de regressão logística foi usado para determinar os determinantes do nanismo, controlando todos os possíveis fatores de confusão. A prevalência geral de baixa estatura em crianças foi de 40,5%, entre as crianças 36,1% dos meninos e 46,3% das meninas com baixa estatura. A prevalência de baixa estatura em crianças menores de 5 anos foi de 50,7%. Crianças do sexo feminino (OR = 1,35, IC de 95%: 0,94-2,0), crianças de 13-24 meses (OR = 6,5, IC de 95%: 3,0-13,9), mães de 15-24 anos (OR = 4,4, IC de 95%: 2,6-7,2), família conjunta (OR = 2,1, IC 95%: 1,4-3,0) não tiveram acesso a água potável de qualidade (OR = 3,3, IC 95%: 1,9-5,9) e a banheiro (OR = 2,8, IC de 95%, 1,9-4,3), enquanto as crianças do distrito de Nowshera (OR = 1,7, IC de 95%: 0,9-3,2) foram significativamente (P 0,05) associadas na análise univariada. O modelo de regressão revelou que a idade da criança, idade materna, tipo de família, qualidade da água e banheiro foram os fatores significativos (P 0,05) que contribuíram para a baixa estatura infantil nas áreas afetadas pelas enchentes. A identificação de fatores-chave pode ser útil para os formuladores de políticas no planejamento de programas comunitários abrangentes para a redução da baixa estatura em áreas afetadas pelas enchentes. Em desastres como enchentes, as consequências prejudiciais do problema de baixa estatura podem ser ainda maiores para as crianças. Educação baseada em evidências e cuidados deve ser fornecida às famílias nas regiões afetadas pelas enchentes para reduzir o problema de nanismo. Os determinantes do retardo de crescimento devem ser almejados pela formulação de políticas abrangentes sobre nutrição adequada, meios de subsistência, água potável e instalações de saneamento nas regiões afetadas pelas enchentes.

Prevalence and determinants of stunting among preschool and school-going children in the flood-affected areas of Pakistan.

Stunting is a significant public health problem in low- and middle-income countries. This study assessed the prevalence of stunting and associated risk factors of stunting among preschool and school-going children in flood-affected areas of Pakistan. A cross-sectional study was conducted by visiting 656 households through multi-stage sampling. Respondent's anthropometric measurements, socio-demographic information and sanitation facilities were explored. A logistic regression model was used to determine determinants of stunting, controlling for all possible confounders. The overall prevalence of stunting in children was 40.5%, among children 36.1% boys and 46.3% of girls were stunted. The prevalence of stunting in under-five children was 50.7%. Female children (OR=1.35, 95% CI:0.94-2.0), children aged 13-24 months (OR=6.5, 95% CI: 3.0-13.9), mothers aged 15-24 years (OR=4.4, 95% CI: 2.6-7.2), joint family (OR=2.1, 95% CI: 1.4-3.0) did not have access to improved drinking water (OR=3.3, 95% CI: 1.9-5.9), and the toilet facility (OR=2.8, 95% CI, 1.9-4.3), while the children from district Nowshera (OR=1.7, 95% CI: 0.9-3.2) were significantly (P<0.05) associated in univariate analysis. The regression model revealed that child age, maternal age, family type, quality of water, and toilet facility, were the significant (P<0.05) factors contributing to child stunting in the flood-hit areas. Identification of key factors might be helpful for policymakers in designing comprehensive community-based programs for the reduction of stunting in flood-affected areas. In disasters such as flood, the detrimental consequences of the stunting problem could be even more on children. Evidence-based education and care must be provided to the families in the flood-affected regions to reduce the stunting problem. The determinants of stunting should be targeted by making comprehensive policies regarding proper nutrition, livelihood, clean water, and sanitation facilities in flood-hit regions.

Potency values from the local lymph node assay: application to classification, labelling and risk assessment.

Hundreds of chemicals are contact allergens but there remains a need to identify and characterise accurately skin sensitising hazards. The purpose of this review was fourfold. First, when using the local lymph node assay (LLNA), consider whether an exposure concentration (EC3 value) lower than 100% can be defined and used as a threshold criterion for classification and labelling. Second, is there any reason to revise the recommendation of a previous ECETOC Task Force regarding specific EC3 values used for sub-categorisation of substances based upon potency? Third, what recommendations can be made regarding classification and labelling of preparations under GHS? Finally, consider how to integrate LLNA data into risk assessment and provide a rationale for using concentration responses and corresponding no-effect concentrations. Although skin sensitising chemicals having high EC3 values may represent only relatively low risks to humans, it is not possible currently to define an EC3 value below 100% that would serve as an appropriate threshold for classification and labelling. The conclusion drawn from reviewing the use of distinct categories for characterising contact allergens was that the most appropriate, science-based classification of contact allergens according to potency is one in which four sub-categories are identified: 'extreme', 'strong', 'moderate' and 'weak'. Since draining lymph node cell proliferation is related causally and quantitatively to potency, LLNA EC3 values are recommended for determination of a no expected sensitisation induction level that represents the first step in quantitative risk assessment.

The development of methods for assessing the in vivo oestrogen-like effects of xenobiotics in CD-1 mice.

The increasing awareness and concern about the potential health risks posed to the ecosystem and to man by endocrine disrupting chemicals with oestrogen-like activity in the environment has focused attention on the need for developing sensitive and specific methods for identifying these xenobiotics and to evaluate their degrees of toxic effects. We have conducted dose response studies in immature (21 days old) CD-1 female mice treated with four compounds, diethylstilboestrol (DES) (0.1 microg to 25 mg/kg body weight), alpha-zearalanol (0.5 mg to 25 mg/kg body weight), methoxychlor (0.5 mg to 500 mg/kg body weight) and bisphenol A (10 microg to 100 mg/kg body weight) administered subcutaneously daily for 3 days, and measured a number of uterine markers in treated and control (vehicle treated) mice. These were, in addition to the commonly measured changes in relative uterus weight and histopathological examination of uterine tissue, three other markers indicative of uterotrophic effects, namely, uterine luminal epithelium BrdU labelling index over the last 24 hr, peroxidase activity and lactoferrin expression. All of these markers showed clear dose-related increases in DES- and methoxychlor-treated animals. In the case of alpha-zearalanol treatment, relative uterine weight, peroxidase activity and lactoferrin expression showed dose-related increases at all the doses investigated. BrdU incorporation (an index of cell proliferation) also progressively increased at dose levels ranging from 0.1 mg to 5.0 mg/kg body weight, but apparently decreased at 25 mg/kg body weight. In contrast to these findings, bisphenol-A treatment showed no consistent changes in any of the four markers at the dose levels investigated. Additionally, studies were also conducted on a number of chemicals in CD-1 mice at one dose level. The chemicals investigated were: bisphenol A (1 g/kg body weight/day), naringenin (1 g/kg body weight/day) o,p'-DDT (500 mg/kg body weight/day), genistein (1 g/kg/day), coumestrol (0.5 mg/kg/day) and chlordecone (20 mg/kg/day) administered subcutaneously daily for 3 days. There was some variability in response of the markers perhaps indicating that the chemicals did not all act in the same way. The findings of our exploratory in vivo studies in CD-1 mice suggest that the measurement of a range of uterine markers, in addition to organ weight and histopathology, would provide useful information on the potential oestrogenicity of chemicals.

Screening of some Indian medicinal plants for their antimicrobial properties.

A total of 82 Indian medicinal plants traditionally used in medicines were subjected to preliminary antibacterial screening against several pathogenic and opportunistic microorganisms. Aqueous, hexane and alcoholic extracts of each plant were tested for their antibacterial activity using agar well diffusion method at sample concentration of 200 mg/ml. The results indicated that out of 82 plants, 56 exhibited antibacterial activity against one or more test pathogens. Interestingly, extracts of five plants showed strong and broad spectrum activity as compared to rest of 51 plant extracts which demonstrated moderate activity. On the whole the alcoholic extracts showed greater activity than their corresponding aqueous and hexane extracts. Among various extracts, only alcoholic extracts of Emblica officinalis, Terminalia chebula, Terminalia belerica, Plumbago zeylanica and Holarrhena antidysenterica were found to show potentially interesting activity against test bacteria. These active crude alcoholic extracts were also assayed for cellular toxicity to fresh sheep erythrocytes and found to have no cellular toxicity.

Glyphosate is an inhibitor of plant cytochrome P450: functional expression of Thlaspi arvensae cytochrome P45071B1/reductase fusion protein in Escherichia coli.

Glyphosate (Roundup) is an herbicide used extensively worldwide which acts as an inhibitor of 5'enolpyruvylshikimate-3-phosphate synthase and for which transgenic herbicide resistant plants have been developed. Here we report for the first time that glyphosate is an inhibitor of cytochrome P450 using a functional expression system for Thlaspi arvensae CYP71B1 in Escherichia coli. CYP71B1 was fused to the soluble domain of a plant cytochrome P450 reductase (CPR) from Catharanthus roseus. CYP71B1 could obtain reducing equivalents in this fusion construct and metabolised the polycyclic aromatic hydrocarbon, benzo(a)pyrene. The fusion protein retained normal spectral characteristics having a Soret peak at 448 nm in the reduced carbon monoxide difference spectrum. Addition of the herbicide resulted in a Type II spectrum indicative of binding via the nitrogen group to haem as a sixth ligand. A Ks of 60 microM was observed and an IC50 of 12 microM was observed for glyphosate inhibition of CYP71B1 activity. The implications of these results are discussed.

Cytochrome P450 3A4 mediated metabolism of 2,4-dichlorophenol.

The metabolism of the environmental pollutant and hepatocarcinogen 2,4-dichlorophenol (2,4-DCP) was studied using microsomal fractions and whole-cells of Saccharomyces cerevisiae containing human cytochrome P450 3A4. 2,4-DCP exhibited a typical type I substrate binding spectrum with a K, of 75 microM. 2,4-DCP was metabolised into two major metabolites identified as 2-chloro-1,4-hydroxyquinone and 2-chloro-1,4-benzoquinone in microsomal fractions and whole cells of yeast expressing human cytochrome P450 3A4. A further metabolite, 1,2,4-hydroxybenzene, was also detected during biotransformation by whole cells, but was not observed in microsomal fractions. 2,4-DCP metabolism was dependent on NADPH in microsomal fractions and no activity was observed in microsomal fractions or whole cells of control transformants. Metabolites were identified by TLC followed by GC-MS.

Metabolism of organochlorine pesticides: the role of human cytochrome P450 3A4.

Organochlorine compounds are widely used as pesticides and are substantial environmental pollutants and carcinogens due to their extensive environmental release. In the present study biotransformation of these pesticides was observed in the microsomal fractions and whole cells of Saccharomyces cerevisiae expressing human cytochrome P450 3A4. In both in vitro and in vivo studies, hexachlorobenzene and pentachlorobenzene were metabolised into pentachlorophenol which was further transformed into tetrachlorohydroquinone. Metabolites were identified by thin layer chromatography and 13C-NMR spectroscopy. The formation of products was observed only in the presence NADPH in microsomal fractions and no activity was observed in control microsomal fractions, or in whole cells.

Human cytochrome P450 3A4 is involved in the biotransformation of the herbicide 2,4-dichlorophenoxyacetic acid.

2,4-Dichlorophenoxyacetic acid (2,4-D) is one of the most frequently used herbicides and is an environmental pollutant. Evidence exists that 2,4-D exposure results in an increased risk for certain malignant disorders such as nasal carcinoma and soft tissue sarcoma in humans and animals. The involvement of cytochrome P450 3A4 (CYP3A4), the major form of monooxygenase enzyme in human liver, in the metabolism of 2,4-D was studied using microsomal fractions and whole cells of Saccharomyces cerevisiae expressing cytochrome P450 3A4. 2,4-Dichlorophenol (2,4-DCP) was identified as the only product of metabolism by TLC followed by NMR and IR spectroscopy and a turnover of 0.13 nmol 2,4-DCP/min/nmol P450 was observed.

Metabolism of the herbicide chlortoluron by human cytochrome P450 3A4.

Studies were carried out to investigate the metabolism of herbicide chlortoluron in the microsomal fractions and whole cells of Saccharomyces cerevisiae expressing human cytochrome P450 3A4. Both whole cells and microsomal fractions of yeast expressing human cytochrome P450 3A4 exhibited a typical dithionite-reduced, CO-difference absorbance spectrum with maximum absorbance at 448 nm. Chlortoluron produced a type I binding spectrum with cytochrome P450 3A4 with a Ks value of 200 microM. Chlortoluron was metabolised into four metabolites; hydroxylated-N-monodemethylated, hydroxylated ring methylated, N-didemethylated and N-monodemethylated products. Chlortoluron metabolism was absolutely dependent on NADPH and no metabolism was observed in control transformants.