Obesity leads to declines in motor skills across childhood.

BACKGROUND: Poor motor skills have been consistently linked with a higher body weight in childhood, but the causal direction of this association is not fully understood. This study investigated the temporal ordering between children's motor skills and weight status at 5 and 10 years. METHODS: Participants were 668 children (54% male) who were studied from infancy as part of an iron deficiency anaemia preventive trial and follow-up study in Santiago, Chile. All were healthy, full-term and weighing 3 kg or more at birth. Cross-lagged panel modelling was conducted to understand the temporal precedence between children's weight status and motor proficiency. Analyses also examined differences in gross and fine motor skills among healthy weight, overweight, and obese children. RESULTS: A higher BMI at 5 years contributed to declines in motor proficiency from 5 to 10 years. There was no support for the reverse, that is, poor motor skills at 5 years did not predict increases in relative weight from 5 to 10 years. Obesity at 5 years also predicted declines in motor proficiency. When compared with normal weight children, obese children had significantly poorer total and gross motor skills at both 5 and 10 years. Overweight children had poorer total and gross motor skills at 10 years only. The differences in total and gross motor skills among normal weight, overweight and obese children appear to increase with age. There were small differences in fine motor skill between obese and non-obese children at 5 years only. CONCLUSIONS: Obesity preceded declines in motor skills and not the reverse. Study findings suggest that early childhood obesity intervention efforts might help prevent declines in motor proficiency that, in turn, may positively impact children's physical activity and overall fitness levels.

Post-Operative Radiation in Early Breast Cancer with N1 Disease: 10-Year Follow-Up.

Post-operative radiotherapy for post-menopausal women with early breast cancer and N1 disease is controversial. Although locoregional control is improved, overall survival (OS) benefit is unclear. The clinical benefit of post-operative irradiation in this group of patients over 10 years was reviewed. We aimed to evaluate the OS, disease-free survival (DFS), and factors affecting OS and DFS. A retrospective review of 191 post-menopausal women with early breast cancer and N1 disease from 2004 to 2011 was performed. Demographics, post-operative histology, adjuvant treatment, OS, and DFS were evaluated. Post-operative radiation was given to 95 of 191 women (49.7%). Younger age at diagnosis (p < 0.001), a greater number of involved nodes (p = 0.004), lymphovascular invasion (LVI), and a higher tumor grade (p = 0.001) were more likely in women who received post-operative radiation. Nodal radiation did not improve 10-year DFS (p = 0.084) or OS (p = 0.203). Post-operative nodal radiation was associated with significant improvement in 10-year OS in women who received only hormonal therapy (p = 0.047) and no other systemic therapy. Women with unfavorable risk factors were more likely to receive post-operative radiation, likely due to a perceived higher risk of recurrence. Nodal radiation did not significantly improve 10-year DFS or OS in early breast cancer patients with N1 disease, and the benefit was not clearly demonstrated. However, in those who were on hormonal therapy, radiotherapy was beneficial in improving overall survival.

CYP2D6 in the brain: genotype effects on resting brain perfusion.

The cytochrome P450 2D6 (CYP2D6) is a genetically polymorphic enzyme involved in the metabolism of several psychoactive drugs. Beside its expression in the liver, CYP2D6 is highly expressed in several regions of the brain, such as the hippocampus, thalamus, hypothalamus and the cortex, but its function in the brain is not well understood. The CYP2D6 enzyme may also have a physiological role due to its involvement in neurotransmitter biotransformation. In this study, CYP2D6 genotyping was performed in N=188 healthy individuals and compared with brain perfusion levels at rest, which may reflect an ongoing biological process regulating the reactivity of the individual to emotional stimuli and the detection of signals evoking fear. Relative to N=42 matched extensive metabolizers, N=14 poor metabolizers were associated with 15% higher perfusion levels in the thalamus (P=0.03 and 0.003). Effects were also present in the whole (N=188) sample divided into metabolizer groups, or finely graded into seven CYP2D6 activity levels. A weaker effect was observed in the right hippocampus (P=0.05). An exploratory analysis, extended to the whole brain, suggested the involvement of CYP2D6 in regions associated with alertness or serotonergic function. These findings support the hypothesis of a functional role of CYP2D6 in the brain.

Over-expression of cyclo-oxygenase-2 predicts poor survival of patients with nasopharyngeal carcinoma: a meta-analysis.

OBJECTIVES: The conclusive prognostic significance of cyclo-oxygenase-2 has been determined in various cancers but not in nasopharyngeal carcinoma. Therefore, this study aimed to evaluate the relationship of cyclo-oxygenase-2 expression with the survival outcome and treatment response of nasopharyngeal carcinoma patients via a systematic meta-analysis approach. METHODS: A meta-analysis was conducted in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses ('PRISMA') checklist. The primary clinical characteristics of patients, and hazard ratios with 95 per cent confidence intervals of overall survival data, were tabulated from eligible studies. The relationship of cyclo-oxygenase-2 expression with survival outcome (expressed as hazard ratio) and treatment response (expressed as odds ratio) in nasopharyngeal carcinoma patients was analysed, and explained with the aid of forest plot charts. RESULTS AND CONCLUSION: The pooled hazard ratio for overall survival was 2.02 (95 per cent confidence interval = 1.65-2.47). This indicates that the over-expression of cyclo-oxygenase-2 is significantly associated with the poor survival of nasopharyngeal carcinoma patients. The pooled odds ratio of 0.98 (95 per cent confidence interval = 0.27-3.49) reveals that over-expression of cyclo-oxygenase-2 was not significantly related to the treatment outcome.

Skeletal myoblast transplantation for attenuation of hyperglycaemia, hyperinsulinaemia and glucose intolerance in a mouse model of type 2 diabetes mellitus.

AIMS/HYPOTHESIS: We aimed to demonstrate the feasibility and efficacy of intra-muscular transplantation of human skeletal myoblasts (hSkMs) for attenuation of hyperglycaemia and improvement of insulin sensitivity using a mouse model of type 2 diabetes mellitus. METHODS: KK Cg-Ay/J mice, aged 12 to 14 weeks, underwent an initial intraperitoneal glucose tolerance test (GTT) and were divided into the following groups: KK control group, basal medium (M199) only; KK myoblast group, with hSkM transplantation; KK fibroblast group, with human fibroblast transplantation. Non-diabetic C57BL mice were used as an additional normal control and also had hSkM transplantation. Cells were transplanted intra-muscularly into the skeletal muscles of the mice. All animals were treated with ciclosporin for 6 weeks only. HbA(1c) and fasting GTT, as well as serum adiponectin, cholesterol, insulin and triacylglycerol were studied. RESULTS: Immunohistochemistry studies showed extensive survival of the transplanted hSkMs in the skeletal muscles at 12 weeks, with nuclei of the hSkMs integrated into the host muscle fibres. Repeat GTT showed a significant decrease in glucose concentrations in the KK myoblast group compared with the KK control and KK fibroblast groups. The KK myoblast group also had reduced mean HbA(1c), cholesterol, insulin and triacylglycerol, and increased adiponectin compared with the KK control and KK fibroblast groups. C57BL mice showed no change in glucose homeostasis after hSkM transplant. CONCLUSIONS/INTERPRETATION: Human skeletal myoblast transplantation attenuated hyperglycaemia and hyperinsulinaemia and improved glucose tolerance in the KK mouse. This novel approach of improving muscle insulin resistance may be a potential alternative treatment for type 2 diabetes mellitus.

Xenogenetics in multifactorial disease susceptibility.

Susceptibility to multifactorial disease includes both genetic and environmental components. These two aspects of susceptibility are interlinked through genetic control of an individual's response to the environment. As a first step in identifying disease susceptibility genes that influence the response of an individual to foreign compounds (xenobiotics), it is necessary to study disorders in which there is an identified environmental trigger. Establishing a DNA resource from individuals with known environmental exposure ('a xenogenetic register') for diseases with an established environmental aetiology is an essential step in beginning to understand how environmental factors contribute to the susceptibility to polygenic diseases. A complementary approach to identification of environmental factors is suggested using a comparison of genetically homogeneous subdivisions of individuals with polygenic diseases where there is no clue to the environmental trigger.

Inhaled corticosteroids for stable chronic obstructive pulmonary disease.

BACKGROUND: The role of inhaled corticosteroids (ICS) in chronic obstructive pulmonary disease (COPD) has been the subject of much controversy. Major international guidelines recommend selective use of ICS. Recently published meta-analyses have reported conflicting findings on the effects of inhaled steroid therapy in COPD. OBJECTIVES: The objective of the review is to determine the efficacy of regular use of inhaled corticosteroids in patients with stable COPD. SEARCH STRATEGY: A pre-defined search strategy was used to search the Cochrane Airways Group specialised register for relevant literature. Searches are current as of October 2006. SELECTION CRITERIA: We selected randomised trials comparing any dose of any type of inhaled steroid with a placebo control in patients with COPD. Acute bronchodilator reversibility to short term beta2-agonists and bronchial hyperresponsiveness were not exclusion criteria. The a priori primary outcome was change in lung function. Data on mortality, exacerbations, quality of life and symptoms, rescue bronchodilator use, exercise capacity, biomarkers and safety were also analysed. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed trial quality and extracted data. Study authors were contacted for additional information. Adverse effects information was collected from the trials. MAIN RESULTS: Forty-seven primary studies with 13,139 participants met the inclusion criteria. Medium term use of ICS (> two months and up to six months) resulted in a small improvement in FEV1 in some studies. Long term use of ICS (> six months) did not significantly reduce the rate of decline in FEV1 in COPD patients (weighted mean difference (WMD) 5.80 ml/year with ICS over placebo, 95% CI -0.28 to 11.88, 2333 participants). There was no statistically significant effect on mortality in COPD patients (OR 0.98, 95% CI 0.83 to 1.16, 8390 participants). Long term use of ICS reduced the mean rate of exacerbations in those studies where pooling of data was possible (WMD -0.26 exacerbations per patient per year, 95% CI -0.37 to -0.14, 2586 participants). ICS slowed the rate of decline in quality of life, as measured by the St George's Respiratory Questionnaire (WMD -1.22 units/year, 95% CI -1.83 to -0.60, 2507 participants). Response to ICS was not predicted by oral steroid response, bronchodilator reversibility or bronchial hyper-responsiveness in COPD patients. There was an increased risk of oropharyngeal candidiasis (OR 2.49, 95% CI 1.78 to 3.49, 4380 participants) and hoarseness. The few long term studies that measured bone effects generally showed no major effect on fractures and bone mineral density over 3 years. AUTHORS' CONCLUSIONS: Patients and clinicians should balance the potential benefits of inhaled steroids in COPD (reduced rate of exacerbations, reduced rate of decline in quality of life), against the known increase in local side effects (oropharyngeal candidiasis and hoarseness). The risk of long term adverse effects is unknown.

Structure and mechanism of arylamine N-acetyltransferases.

Arylamine N-acetyltransferases (NATs) are a family of phase II drug-metabolising enzymes which are important in the biotransformation of various aromatic and heterocyclic amines and hydroxylamines, arylhydrazines and arylhydrazides. NATs are present in a wide range of eukaryotes and prokaryotes. Humans have two functional NAT isoforms, both of which are highly polymorphic. The pharmacogenetics of NATs is an area which has been extensively studied. The determination of the X-ray crystal structure of NAT from Salmonella typhimurium led to the identification of the catalytically essential triad of residues: Cys-His-Asp, which is present in all functional NAT enzymes. Recent co-crystallisation data and in silico docking studies of NAT from Mycobacterium smegmatis with substrates and inhibitors have aided the identification of important contact residues within the active site. The X-ray crystal structures of four prokaryotic NAT proteins have now been determined, and these have been used to generate structural models of eukaryotic NATs, providing valuable insight into their active-site architecture. In addition to aiding crystallographic experiments, recent progress in the production of recombinant prokaryotic and eukaryotic NATs has allowed comparative studies of the kinetics and activity profiles of these enzymes. In this review we present an overview of recent structural and activity studies on NAT enzymes, and we outline how in silico methods may be used to predict NAT protein-ligand interactions based on the current knowledge.

Self-Assembled Silica Nanostructures: Simultaneous Discrimination of Handedness, Pitch and Diameter of Helical Silica Nanotubes.

The left- and right-handed helical silica nanostructures were obtained with the aid of organic templates, the formation of the nanostructures might follow a co-operation self-assembly mechanism. The chirality of the organogel self-assemblies was successfully transcribed in to the silica. The helical pitch and pore size of the silica nanotubes sensitively depended on the optical purity of the neutral gelator in the reaction mixtures.

Comparison of the membrane-bound and detergent-solubilised hydrogenase from paracoccus denitrificans. Isolation of the hydrogenase.

The hydrogenase from Paracoccus denitrificans is an integral membrane protein and has been solubilised by Triton X-100. The membrane-bound and detergent-solubilised forms of the enzyme have been compared. Both forms of the enzyme show a pH optimum for reduction of benzyl viologen at pH 8.5--9.0 and are both inhibited by concentrations of NaCl greater than 30 mM. An Arrhenius plot of the activity of hydrogenase in the membrane shows no 'break'. The form of the Arrhenius plot and the activation energy are not significantly changed on solubilisation of the enzyme. The Km and V values for benzyl viologen, methyl viologen and H2 are unaltered when the enzyme is extracted from the membrane. Therefore, solubilisation of hydrogenase from the membrane by Triton X-400 is unlikely to disrupt the native conformation of the enzyme. The detergent-solubilised hydrogenase has subsequently been purified using ammonium sulphate precipitation, sucrose density gradient centrifugation and chromatography on hydroxyapatite. The overall yield of activity is 23%, with a final purification of over 100-fold.

Drug metabolising N-acetyltransferase activity in human cell lines.

Many arylamine and hydrazine drugs and xenobiotics are acetylated by N-acetyltransferase (NAT), a cytosolic enzymic activity which has a wide tissue distribution. Humans can be classified as either fast or slow acetylators on the basis of their ability to metabolise isoniazid or sulphamethazine. These are termed polymorphic substrates. The acetylation of other compounds does not vary amongst individuals, e.g., p-aminobenzoic acid, and are termed monomorphic substrates. NAT from human hepatic and non-hepatic tissues, viz., (i) liver, (ii) the hepatoma cell line HepG2, (iii) tonsil lymphocytes and (iv) the monocytic cell line U937 have been compared with respect to substrate specificity towards polymorphic and monomorphic substrates. The chromatographic and centrifugation behaviour of NAT from these sources has also been investigated. NAT from liver shows 2-fold greater activity towards sulphamethazine than towards p-aminobenzoic acid as substrate. All other cell types tested show at least 70-fold greater activity with p-aminobenzoic as substrate compared to sulphamethazine. NAT from HepG2 cells, U937 cells and tonsil lymphocytes migrates as a single peak during ion-exchange chromatography, whereas the liver NAT activity is separated into two peaks. NAT in HepG2 cells resembles extra-hepatic tissue NAT rather than NAT in liver. HepG2 cells do not therefore represent a good in vitro model for investigation of human metabolism of arylamines or hydrazines. The molecular weight of NAT from U937 cells has been determined by a combination of sucrose density gradient centrifugation and gel filtration to be 31,600 +/- 1200 daltons.

Placental arylamine N-acetyltransferase type 1: potential contributory source of urinary folate catabolite p-acetamidobenzoylglutamate during pregnancy.

Human arylamine N-acetyltransferase type 1 (NAT1), better known as a drug-metabolising enzyme, has been proposed to acetylate the folate catabolite p-aminobenzoylglutamate (p-abaglu) to N-acetamidobenzoylglutamate (ap-abaglu) which is a major urinary folate catabolite. Using mass spectroscopic analysis, we demonstrate the formation of ap-abaglu by recombinant human NAT1 and human placental homogenates. Using density gradient centrifugation the placental enzymic activity which acetylates p-aba and the placental enzymic activity acetylating p-abaglu both have an S(20,w) value of 3.25 S. This is the expected value for a monomer of human NAT1 (33 kDa). The specific NAT1 inhibitor 5-iodosalicylate inhibits acetylation of both p-aba and p-abaglu catalysed by either recombinant human NAT1 or placental samples as the source of enzyme. These data demonstrate that NAT1 is the major placental enzyme involved in acetylating p-abaglu.

The interaction of soluble human complement receptor type 1 (sCR1, BRL55730) with human complement component C4.

Human CR1 is a membrane-bound protein which plays an important role in the control of the human complement system. In addition to its involvement in the processing and clearance of immune complexes with C3b or C4b on their surface, CR1 acts as a cofactor for the proteolysis of C3b and C4b by Factor I. sCR1 is a recombinant, soluble form of CR1 which retains the cofactor activities of CR1, and is of potential therapeutic value for the suppression of complement-mediated tissue damage in vivo. An assay has been established using microtitre plates to explore the binding of sCR1 to the two isotypes of C4, C4A and C4B, and to C4 fragments. Specific binding of 125I-sCR1 to C4b and ammonia-treated C4 has been demonstrated. The binding of 125I-sCR1 to ammonia-treated C4 is dependent on pH and ionic strength, decreasing with an increase in pH and with an increase in ionic strength. At physiological ionic strength, up to twice as much 125I-sCR1 bound to ammonia-treated C4A as bound to ammonia-treated C4B. This preference of sCR1 for binding to the C4A isotype has implications for the clinical association of immune complex disease with C4A null alleles.

Arylamine N-acetyltransferases - of mice, men and microorganisms.

Arylamine N-acetyltransferases (NATs) catalyse the transfer of an acetyl group from acetyl CoA to the terminal nitrogen of hydrazine and arylamine drugs and carcinogens. These enzymes are polymorphic and have an important place in the history of pharmacogenetics, being first identified as responsible for the polymorphic inactivation of the anti-tubercular drug isoniazid. NAT has recently been identified within Mycobacterium tuberculosis itself and is an important candidate for modulating the response of mycobacteria to isoniazid. The first three-dimensional structure of the unique NAT family shows the active-site cysteine to be aligned with conserved histidine and aspartate residues to form a catalytic triad, thus providing an activation mechanism for transfer of the acetyl group from acetyl CoA to cysteine. The unique fold could allow different members of the NAT family to play a variety of roles in endogenous and xenobiotic metabolism.

Upper gastrointestinal tract bleeding from oral potassium chloride. Comparative risk from microencapsulated vs wax-matrix formulations.

A retrospective cohort study was performed to assess the relative risk of upper gastrointestinal (UGI) tract bleeding from two formulations of potassium chloride. Relevant information was obtained from 1980 through 1984 Medicaid billing data from the states of Michigan, Minnesota, Florida, and Ohio. After patients with a history of UGI tract bleeding prior to their first prescription for either of the two potassium chloride preparations under study were excluded, data were analyzed for 28,790 patients (143,512 patient-months) dispensed a microencapsulated formulation exclusively and 76,118 patients (560,341 patient-months) dispensed a wax-matrix formulation exclusively. The risk of UGI tract bleeding within 30 days after each prescription for the drug of interest was examined. After sampling from the undiseased study subjects and adjusting for multiple potential confounding variables using logistic regression, an odds ratio (95% confidence interval) of 0.67 (0.52 to 0.85) was observed.

Off-pump coronary artery bypass grafting is a safe and effective treatment modality for Asian patients requiring coronary revascularisation.

INTRODUCTION: Off-pump coronary artery bypass grafting (OPCABG) is gaining widespread acceptance as the preferred choice for myocardial revascularisation. However, no definite data exist as to whether it is better than conventional CABG. We aimed to study the efficacy of the procedure in our patients, which constituted of a predominantly Asian population. METHODS: Between January 2000 and December 2002, 1062 patients underwent isolated coronary artery bypass in our institution. 184 patients (17.3 percent) underwent OPCABG. Patients were preoperatively prospectively risk stratified under the EuroSCORE risk assessment model under high, medium and low risk classes thereby making them comparable. Post-operative complications, intensive care unit stay, hospital stay, types of grafts done were then analysed in these different risk classes. RESULTS: The incidence of off-pump procedures showed a gradual increase over the last three years in this institution. A reduction in the number of post-operative complications, hospital stay, intensive care unit stay and mortality in the off-pump group was observed. Certain differences were found to be statistically significant. CONCLUSION: Off-pump CABG is a safe and viable alternative to conventional CABG as a treatment modality for surgical coronary revascularisation.

Multivariate assessment of site of lingual nerve.

Injury to the lingual nerve can cause debilitating symptoms. The nerve lies in the retromolar region and its anatomical site can vary within patients and according to sex, age, and dentate status. To our knowledge, no previous studies have recorded its course from multiple bony landmarks and examined the association between age, dentate status, and sex, in the same sample. We dissected 30 white cadavers and took primary and secondary reference points from the internal oblique ridge. We measured the distance to the lingual nerve in sagittal, vertical, and horizontal planes, and recorded the position where the nerve was closest to the lingual plate. We dissected 46 hemimandibles (23 male, mean age 79 years, range 52-100) of which 26 were from the left side. Mean (SD) sagittal, vertical, and horizontal distances from the primary reference point were 9.29 (3.41)mm, 9.15 (3.87)mm, and 0.57 (0.56)mm, respectively. Mean (SD) vertical and horizontal distances from the secondary point were 7.79 (5.45) mm and 0.59 (0.64)mm, respectively. The proximity of the nerve to the lingual plate varied widely (range -13.00 to 15.17mm from the primary reference point). Dentate status was significant for the sagittal measurement from the primary point, and the vertical measurement from the secondary point. Differences in age, sex, or site of the contralateral nerve were not significant (n=16 pairs). Our findings suggest that the site of the nerve is consistent between and within subjects for sex and age, but not for dentate status. The association between the nerve and the lingual plate varied, which suggests that care must be taken when operating in the area.

Localization of polymorphic N-acetyltransferase (NAT2) in tissues of inbred mice.

Like humans, mice exhibit polymorphism in the N-acetylation of aromatic amines, many of which are toxic and/or carcinogenic. Mice have three N-acetyltransferase (Nat) genes, Nat1, Nat2 and Nat3, and Nat2 is known to be polymorphic. There is a dramatic difference in the acetylation of NAT2 substrates by blood from fast (C57BL/6J) compared with slow acetylator (A/J) mice. However, the acetylation of these substrates by liver cytosols from the two strains is very similar. In order to determine whether the expression of the NAT2 protein corresponded with the activities measured, a polyclonal antipeptide antisera was raised against the C-terminal decapeptide of NAT2 and characterized using recombinant murine NAT2 antigen. Enzyme-linked immunosorbent assays (ELISAs) demonstrated that the anti-NAT2 antiserum bound in a concentration-dependent fashion to recombinant NAT2. Immunochemical analysis of mouse liver cytosols from C57BL/6J or A/J livers indicated that the level of NAT2 protein expressed in the two strains was similar. Immunohistochemical staining of C57BL/6J liver with anti-NAT2 antiserum showed that NAT2 was expressed in hepatocytes throughout the liver although the intensity of staining in the perivenous (centrilobular) region was higher than that in the periportal region. NAT2 was also detected in epithelial cells in the lung, kidney, bladder, small intestine and skin as well as in erythrocytes and lymphocytes in the spleen and hair follicles and sebaceous glands in the skin. Characterization of the distribution of NAT2 will be of value in elucidating the role of polymorphic N-acetylation in protecting the organism from environmental insults as well as in endogenous metabolism.

Genotyping human polymorphic arylamine N-acetyltransferase: identification of new slow allotypic variants.

Arylamine N-acetyltransferase catalyses the N-acetylation of primary arylamine and hydrazine drugs and chemicals. N-acetylation is subject to a polymorphism and humans can be categorized as either fast or slow acetylators according to their ability to N-acetylate polymorphic substrates in vivo. Previously, slow acetylation has been linked to four distinct polymorphic N-acetyltransferase (pnat) alleles each of which contains one or more point mutations within the coding region of the pnat gene. One new rare slow variant of pnat has been identified by cloning and sequencing the pnat DNA from an individual whose NAT phenotype was determined by in vivo acetylation of the polymorphic substrate sulphamethazine. This allele, designated S1c, differs from the wild type fast allele at nucleotide positions 341 and 803. A second new rare slow allotypic variant, designated S3, has been identified by resistance of the pnat specific DNA to digestion with the restriction enzymes Fok I and Bam HI. A method of genotyping individuals for the arylamine N-acetyltransferase (NAT) polymorphism is presented which correctly predicts the phenotype of greater than 95% (21 of 22) of individuals as measured by the extent of acetylation of sulphamethazine in urine. This refined genotyping method was applied to a clinical population of 48 Caucasians with classical or definite rheumatoid arthritis each receiving daily between 150 and 500 mg of the anti-rheumatic drug, D-penicillamine. There is no difference in the N-acetyltransferase phenotype of the individuals who developed proteinuria and the control group with no adverse effects.

Genes for human arylamine N-acetyltransferases in relation to loss of the short arm of chromosome 8 in bladder cancer.

Polymorphisms of N-acetyltransferase type 2 (NAT2) conferring the slow acetylator phenotype have been linked to increased susceptibility to arylamine-induced bladder cancer in Caucasians. Genes for NAT2, the other NAT isozyme, NAT1, and a NAT pseudogene (NATP) are found on 8p22, a region displaying loss of heterozygosity, particularly in invasive bladder tumours. A restriction enzyme digestion map has defined the relative positions of the NAT genes to each other and to adjacent CpG islands. NAT2, as a polymorphic gene of known function, is a potentially valuable marker for the detection of loss of heterozygosity in 8p22. Two approaches to investigate loss of heterozygosity at the NAT2 locus in bladder tumours have been used. (1) A cosmid containing NAT2 has been used in fluorescence in-situ hybridization on human exfoliated bladder cells collected from unselected bladder cancer outpatients. Loss of signal from the NAT2 cosmid was found in nine of the 20 patients. (2) A panel of 13 human bladder tumours was investigated for loss of heterozygosity using the polymorphism in the NAT2 gene as a marker. Loss of heterozygosity at the NAT2 locus has been compared with loss of heterozygosity at adjacent microsatellite marker sites known to be located on 8p. There is agreement between loss of heterozygosity at the NAT2 locus and adjacent microsatellite marker loci in 11 of the tumours but two of the tumours appear to show retention at the NAT2 locus. More extensive mapping of the region around the NAT loci, particularly on the centromeric side, is important to pinpoint possible tumour suppressor genes or their modifiers in the region. There are no other expressed sequences known in this region and therefore NAT genes are important genetic landmarks.