Flavin-containing monooxygenases: mutations, disease and drug response

NOTICE: this is the author’s version of a work that was accepted for publication in Trends in Pharmacological Sciences. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Trends in Pharmacological Sciences, [VOL 29, ISSUE 6, (2008)] DOI: 10.1016/j.tips.2008.03.00

Trimethylaminuria

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Drug metabolism by flavin-containing monooxygenases of human and mouse

Introduction: Flavin-containing monooxygenases (FMOs) play an important role in drug metabolism. / Areas covered: We focus on the role of FMOs in the metabolism of drugs in human and mouse. We describe FMO genes and proteins of human and mouse; the catalytic mechanism of FMOs and their significance for drug metabolism; differences between FMOs and CYPs; factors contributing to potential underestimation of the contribution of FMOs to drug metabolism; the developmental and tissue-specific expression of FMO genes and differences between human and mouse; and factors that induce or inhibit FMOs. We discuss the contribution of FMOs of human and mouse to the metabolism of drugs and how genetic variation of FMOs affects drug metabolism. Finally, we discuss the utility of animal models for FMO-mediated drug metabolism in humans. / Expert opinion: The contribution of FMOs to drug metabolism may be underestimated. As FMOs are not readily induced or inhibited and their reactions are generally detoxifications, the design of drugs that are metabolized predominantly by FMOs offers clinical advantages. Fmo1(-/-),Fmo2(-/-),Fmo4(-/-) mice provide a good animal model for FMO-mediated drug metabolism in humans. Identification of roles for FMO1 and FMO5 in endogenous metabolism has implications for drug therapy and initiates an exciting area of research

The integration and interpretation of pharmacogenomics. A comparative study between the United States of America and Europe: towards better health care

The study of pharmacogenomics has, by harnessing sequence information from human genomes, the potential to lead to novel approaches in drug discovery, an individualized application of drug therapy, and new insights into disease prevention. For this potential to be realized results need to be interpreted to the prescriber into a format which dictates an action. This mini review briefly describes the history, the regulatory environment, opinions towards, and implementation, integration and interpretation of pharmacogenomics in the United States of America and Europe. The article discusses also how interpretation of pharmacogenomics could move forward to better implementation in health care

Selection of men for investigation of possible testicular cancer in primary care: a large case-control study using electronic patient records

This is the author accepted manuscript. The final version is available from the Royal College of General Practitioners via the DOI in this record.BACKGROUND: Testicular cancer incidence has risen over the last two decades and is expected to continue to rise. There are no primary care studies on the clinical features of testicular cancer, with recent National Institute for Health and Care Excellence (NICE) guidance based solely upon clinical consensus. AIM: To identify clinical features of testicular cancer and to quantify their risk in primary care patients, with the aim of improving the selection of patients for investigation. DESIGN AND SETTING: A matched case-control study in males aged ≥17 years, using Clinical Practice Research Datalink records. METHOD: Putative clinical features of testicular cancer were identified and analysed using conditional logistic regression. Positive predictive values (PPVs) were calculated for those aged <50 years. RESULTS: In all, 1398 cases were available, diagnosed between 2000 and 2012, with 4956 age-, sex-, and practice-matched controls. Nine features were independently associated with testicular cancer, the top three being testicular swelling (odds ratio [OR] 280, 95% confidence interval [CI] = 110 to 690), testicular lump (OR 270, 95% CI = 100 to 740), and scrotal swelling (OR 170, 95% CI = 35 to 800). The highest PPV for 17-49-year-olds was testicular lump, at 2.5% (95% CI = 1.1 to 5.6). Combining testicular lump with testicular swelling or testicular pain produced PPVs of 17% and 10%, respectively. CONCLUSION: Testicular enlargement carries a risk of cancer of 2.5% - close to the current 3% threshold in UK referral guidance. Contrary to traditional teaching, painful testicular enlargement may signify cancer. Some initial hydrocele diagnoses appear to be wrong, with missed cancers, suggesting an ultrasound may be useful when a hydrocele diagnosis is uncertain. These results support the existing NICE guidelines, and help to characterise when an ultrasound should be considered in symptomatic men.Funding was provided by the Policy Research Unit in Cancer Awareness, Screening and Early Diagnosis. The views expressed in this paper are those of the authors and not necessarily those of the NHS, the Department of Health, or the Policy Research Unit, which receives funding for a research programme from the Department of Health Policy Research Programme. It is a collaboration between researchers from seven institutions (Queen Mary University of London, University College London [UCL], King’s College London, London School of Hygiene and Tropical Medicine, Hull York Medical School, Durham University, and University of Exeter Medical School)

Flavin-containing monooxygenases: new structures from old proteins

A study reports the structures of membrane-bound flavin-containing monooxygenases (FMOs), solved using reconstructed ancestral mammalian FMOs. The models provide a structural basis for these enzymes’ mechanism of action and show how the proteins interact with membranes and how substrates access their active sites

Trimethylamine and trimethylamine N-oxide, a flavin-containing monooxygenase 3 (FMO3)-mediated host-microbiome metabolic axis implicated in health and disease

Flavin-containing monooxygenase 3 (FMO3) is known primarily as an enzyme involved in the metabolism of therapeutic drugs. However, on a daily basis we are exposed to one of the most abundant substrates of the enzyme, trimethylamine, which is released from various dietary components by the action of gut bacteria. FMO3 converts the odorous trimethylamine to non-odorous trimethylamine N-oxide, which is excreted in urine. Impaired FMO3 activity gives rise to the inherited disorder primary trimethylaminuria. Affected individuals cannot produce trimethylamine N-oxide and, consequently, excrete large amounts of trimethylamine. A dysbiosis in gut bacteria can give rise to secondary trimethylaminuria. Recently, there has been much interest in FMO3 and its catalytic product trimethylamine N-oxide. This is because trimethylamine N-oxide has been implicated in various conditions affecting health, including cardiovascular disease, reverse cholesterol transport and glucose and lipid homeostasis. In this review, we consider the dietary components that can give rise to trimethylamine, the gut bacteria involved in the production of trimethylamine from dietary precursors, the metabolic reactions by which bacteria produce and utilize trimethylamine and the enzymes that catalyze the reactions. Also included is information on bacteria that produce trimethylamine in the oral cavity and vagina, two key microbiome niches that can influence health. Finally, we discuss the importance of the trimethylamine/trimethylamine N-oxide microbiome-host axis in health and disease, considering factors that affect bacterial production and host metabolism of trimethylamine, the involvement of trimethylamine N-oxide and FMO3 in disease and the implications of the host-microbiome axis for management of trimethylaminuria

A highly sensitive liquid chromatography electrospray ionization mass spectrometry method for quantification of TMA, TMAO and creatinine in mouse urine

Our method describes the quantification in mouse urine of trimethylamine (TMA), trimethylamine N-oxide (TMAO) and creatinine. The method combines derivatization of TMA, with ethyl bromoacetate, and LC chromatographic separation on an ACE C18 column. The effluent was continuously electrosprayed into the linear ion trap mass spectrometer (LTQ), which operated in selective ion monitoring (SIM) modes set for targeted analytes and their internal standards (IS). All validation parameters were within acceptable ranges of analytical method validation guidelines. Intra- and inter-day assay precision and accuracy coefficients of variation were <3.1%, and recoveries for TMA and TMAO were 97–104%. The method developed uses a two-step procedure. Firstly, TMA and TMAO are analyzed without a purification step using a 5-min gradient cap-LC- SIMs analysis, then creatinine is analyzed using the same experimental conditions. The method is robust, highly sensitive, reproducible and has the high-throughput capability of detecting TMA, TMAO and creatinine at on-column concentrations as low as 28 pg/mL, 115 pg/mL and 1 ng/mL, respectively. The method is suitable for analysis of TMA, TMAO and creatinine in both male and female mouse urine. / The key benefits of the method are: The small sample volume of urine required, which overcomes the difficulties of collecting sufficient volumes of urine at defined times. / No sample pre-treatment is necessary. / The quantification of TMA, TMAO and creatinine using the same cap-LC-MS method

How useful is thrombocytosis in predicting an underlying cancer in primary care? Systematic review protocol

Early diagnosis of cancer is imperative to reduce the cancer burden in the UK and improve cancer survival. Identifying early markers of cancer can help general practitioners to direct patients at the greatest risk of cancer to appropriate investigative services. A raised platelet count, or thrombocytosis, has been linked to malignancy and identified as a marker of poor prognosis in secondary care, but there is little evidence around the importance of this marker in a primary care setting, within a diagnostic context. This review aims to identify and explore the body of evidence concerning the association between thrombocytosis and cancer in primary care. This protocol was produced using guidance from the PRISMA-P statement

Symptoms of adult chronic and acute leukaemia before diagnosis: large primary care case-control studies using electronic records

This is the author accepted manuscript. The final version is available from Royal College of General Practitioners via the DOI in this record.BACKGROUND: Leukaemia is the eleventh commonest UK cancer. The four main subtypes have different clinical profiles, particularly between chronic and acute types. AIM: To identify the symptom profiles of chronic and acute leukaemia in adults in primary care. DESIGN AND SETTING: Matched case-control studies using Clinical Practice Research Datalink records. METHOD: Putative symptoms of leukaemia were identified in the year before diagnosis. Conditional logistic regression was used for analysis, and positive predictive values (PPVs) were calculated to estimate risk. RESULTS: Of cases diagnosed between 2000 and 2009, 4655 were aged ≥40 years (2877 chronic leukaemia (CL), 937 acute leukaemia (AL), 841 unreported subtype). Ten symptoms were independently associated with CL, the three strongest being: lymphadenopathy (odds ratio [OR] 22, 95% confidence interval [CI] = 13 to 36), weight loss (OR 3.0, 95% CI = 2.1 to 4.2), and bruising (OR 2.3, 95% CI = 1.6 to 3.2). Thirteen symptoms were independently associated with AL, the three strongest being: nosebleeds and/or bleeding gums (OR 5.7, 95% CI = 3.1 to 10), fever (OR 5.3, 95% CI = 2.7 to 10), and fatigue (OR 4.4, 95% CI = 3.3 to 6.0). No individual symptom or combination of symptoms had a PPV >1%. CONCLUSION: The symptom profiles of CL and AL have both overlapping and distinct features. This presents a dichotomy for GPs: diagnosis, by performing a full blood count, is easy; however, the symptoms of leukaemia are non-specific and of relatively low risk. This explains why many leukaemia diagnoses are unexpected findings.This article presents independent research funded by the National Institute for Health Research (NIHR) under its Programme Grants for Applied Research Programme (Grant Reference Number RP-PG-0608– 10045). Fiona M Walter is part-funded by an NIHR Clinician Scientist award. Richard D Neal is part-funded by Public Health Wales and Betsi Cadwaladr University Health Board. Willie Hamilton is supported by the NIHR Collaboration for Leadership in Applied Health Research and Care South West Peninsula at the Royal Devon and Exeter NHS Foundation Trust. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR, or the Department of Health