Human N-acetyltransferase 2 (NAT2) gene variability in Brazilian populations from different geographical areas.

Introduction: Several polymorphisms altering the NAT2 activity have already been identified. The geographical distribution of NAT2 variants has been extensively studied and has been demonstrated to vary significantly among different ethnic population. Here, we describe the genetic variability of human N-acetyltransferase 2 (NAT2) gene and the predominant genotype-deduced acetylation profiles of Brazilians. Methods: A total of 964 individuals, from five geographical different regions, were genotyped for NAT2 by sequencing the entire coding exon. Results: Twenty-three previously described NAT2 single nucleotide polymorphisms (SNPs) were identified, including the seven most common ones globally (c.191G>A, c.282C>T, c.341T>C, c.481C>T, c.590G>A, c.803A>G and c.857G>A). The main allelic groups were NAT2*5 (36%) and NAT2*6 (18.2%), followed to the reference allele NAT2*4 (20.4%). Combined into genotypes, the most prevalent allelic groups were NAT2*5/*5 (14.6%), NAT2*5/*6 (11.9%) and NAT2*6/*6 (6.2%). The genotype deduced NAT2 slow acetylation phenotype was predominant but showed significant variability between geographical regions. The prevalence of slow acetylation phenotype was higher in the Northeast, North and Midwest (51.3%, 45.5% and 41.5%, respectively) of the country. In the Southeast, the intermediate acetylation phenotype was the most prevalent (40.3%) and, in the South, the prevalence of rapid acetylation phenotype was significantly higher (36.7%), when compared to other Brazilian states (p < 0.0001). Comparison of the predicted acetylation profile among regions showed homogeneity among the North and Northeast but was significantly different when compared to the Southeast (p = 0.0396). The Southern region was significantly different from all other regions (p < 0.0001). Discussion: This study contributes not only to current knowledge of the NAT2 population genetic diversity in different geographical regions of Brazil, but also to the reconstruction of a more accurate phenotypic picture of NAT2 acetylator profiles in those regions.

Predicting Obstructive Sleep Apnea in Patients with Insomnia: A Comparative Study with Four Screening Instruments.

PURPOSE: Obstructive sleep apnea (OSA) and insomnia are very prevalent disorders, especially in sleep-lab setting, and insomnia may be the presenting complaint of OSA. Here, we aimed to validate No-Apnea as screening tool for OSA in patients with self-reported insomnia complaints and to compare its performance with other models. METHODS: This cross-sectional study involved evaluation of No-Apnea as well as STOP-Bang, NoSAS and Epworth Sleepiness Scale (ESS) in subjects with insomnia being evaluated with full in-lab polysomnography. Discrimination was assessed by area under the curve (AUC), while predictive parameters were calculated by contingency tables. OSA severity was classified based on the apnea/hypopnea index: ≥ 5.0/h as any OSA (OSA≥5), ≥ 15.0/h as moderate/severe OSA (OSA≥15), and ≥ 30.0/h as severe OSA (OSA≥30). RESULTS: Overall, 2591 patients with a clinical diagnosis of insomnia were included. Diagnosis of OSA≥5, OSA≥15, and OSA≥30 was of 76.3%, 53.1%, and 32.6%, respectively. At all levels of OSA severity, No-Apnea had sensitivity ranging from 84.5 to 94.1% and specificity ranging from 58.2 to 35.1%. For screening of OSA≥5, OSA≥15, and OSA≥30, discriminatory ability (AUC) of No-Apnea was: 0.790 [95% confidence interval (CI) 0.770-0.810], 0.758 (95% CI 0.740-0.777), and 0.753 (95% CI 0.734-0.772), respectively. Based on AUCs, No-Apnea, STOP-Bang, and NoSAS performed similar at all levels of OSA severity. The ESS did not present satisfactory discrimination as OSA screening model. CONCLUSIONS: In a large sample of patients with insomnia, No-Apnea, STOP-Bang, and NoSAS, but not ESS, enable satisfactory and similar discrimination at all levels of OSA severity.

Comparative performance of screening instruments for obstructive sleep apnea in morbidly obese patients referred to a sleep laboratory: a prospective cross-sectional study.

PURPOSE: Obstructive sleep apnea (OSA) is very common occurrence among morbidly obese patients. Our main objectives were to validate the No-Apnea, a 2-item screening tool, in morbidly obese patients and compare its performance with three other instruments: STOP-Bang questionnaire, NoSAS score, and Epworth Sleepiness Scale (ESS). METHODS: A cross-sectional analysis of morbidly obese patients (body mass index [BMI] ≥ 35.0 kg/m2) grouped into two independent samples: bariatric surgery patients (BS) and non-bariatric surgery patients (NBS). All patients underwent overnight polysomnography. Discriminatory ability was assessed by area under the curve (AUC). OSA severity was defined by apnea/hypopnea index cut-off points: ≥ 5.0/h (OSA≥5), ≥ 15.0/h (OSA≥15), and ≥ 30.0/h (OSA≥30). RESULTS: A total of 1017 subjects (40.4% in BS cohort and 59.6% in NBS cohort) were evaluated. In the BS cohort, No-Apnea had similar discrimination to STOP-Bang and NoSAS for predicting OSA≥5 (p = 0.979 and p = 0.358, respectively), OSA≥15 (p = 0.158 and p = 0.399, respectively), and OSA≥30 (p = 0.388 and p = 0.903, respectively). In the NBS cohort, No-Apnea had similar discrimination to STOP-Bang and NoSAS for predicting OSA≥5 (p = 0.528 and p = 0.428, respectively), OSA≥15 (p = 0.825 and p = 0.108, respectively), and OSA≥30 (p = 0.458 and p = 0.186, respectively). Moreover, No-Apnea performed significantly better than ESS in both BS and NBS cohorts (p < 0.001). CONCLUSIONS: No-Apnea is a useful and practical tool for screening of OSA in morbidly obese patients, with non-inferior performance to STOP-Bang questionnaire and NoSAS score.

Fractional Exhaled Nitric Oxide Measurements and Screening of Obstructive Sleep Apnea in a Sleep-Laboratory Setting: A Cross-Sectional Study.

PURPOSE: Obstructive sleep apnea (OSA) is a common condition characterized by repetitive collapse of the upper airways and intermittent oxygen desaturation, which may lead to airway inflammation. Here, we explored whether fractional exhaled nitric oxide (FeNO) levels provide a non-invasive screening tool of OSA. METHODS: Over a 3-month period, FeNO levels were measured in consecutive non-smoking patients referred for a sleep laboratory. All patients underwent full polysomnography. OSA severity was classified based on the apnea/hypopnea index: ≥ 5.0/h as any OSA, ≥ 15.0/h as moderate/severe OSA, and ≥ 30.0/h as severe OSA. FeNO was measured by a portable device (NIOX-MINO®; Aerocrine AB, Solna, Sweden) and expressed as parts per billion (ppb). Discrimination by area under the curve (AUC) and binary logistic regression were performed. RESULTS: A total of 229 subjects were evaluated. Mean FeNO values were similar among subjects without OSA or with OSA: 16.9 ± 10.6 ppb versus 20.2 ± 14.5 ppb, p = 0.221; respectively. FeNO was not an inclusionary parameter to predict any OSA, moderate/severe OSA, and severe OSA: odds ratio (OR) 1.023 (95% confidence interval [CI]: 0.986-1.062); OR 1.012 (95% CI: 0.991-1.034); and OR 0.999 (95% CI: 0.980-1.018), respectively. The AUC values for FeNO in the diagnosis of any OSA, moderate/severe OSA, and severe OSA showed no discriminatory properties: AUC: 0.567 (95% CI: 0.464-0.670), AUC: 0.541 (95% CI: 0.465-0.618), and AUC: 0.535 (95% CI: 0.459-0.610); respectively. CONCLUSIONS: In a sleep-lab setting, our findings suggest that FeNO measurements are inconsequential in the screening of OSA in adults.

Simplifying the Screening of Obstructive Sleep Apnea With a 2-Item Model, No-Apnea: A Cross-Sectional Study.

STUDY OBJECTIVES: To develop and validate a practical model for obstructive sleep apnea (OSA) screening in adults based on objectively assessed criteria, and then compare it with two widely used tools, namely STOP-BANG and NoSAS. METHODS: This is a retrospective study of an existing database of consecutive outpatients who were referred for polysomnography for suspected sleep-disordered breathing by their primary care physicians. Area under the curve (AUC) and 2 × 2 contingency tables were employed to obtain the performance of the new instrument. RESULTS: A total of 4,072 subjects were randomly allocated into two independent cohorts: one for derivation (n = 2,037) and one for validation (n = 2,035). A mnemonic model, named No-Apnea, with two variables (neck circumference and age) was developed (total score: 0-9 points). We used the cutoff ≥ 3 to classify patients at high risk of having OSA. OSA severity was categorized by apnea-hypopnea index (AHI): any OSA (AHI 5 ≥ events/h; OSA-5), moderate/ severe OSA (AHI 15 ≥ events/h; OSA-15); and severe OSA (AHI 30 ≥ events/h; OSA-30). In the derivation cohort, the AUCs for screening of OSA-5, OSA-15, and OSA-30 were: 0.784, 0.758, and 0.754; respectively. The rate of subjects correctly screened was 78.1%, 68.8%, and 54.4%, respectively for OSA-5, OSA-15, and OSA-30. Subsequently, the model was validated confirming its reproducibility. In both cohorts, No-Apnea discrimination was similar to STOP-BANG or NoSAS. CONCLUSIONS: The No-Apnea, a 2-item model, appears to be a useful and practical tool for OSA screening, mainly when limited resources constrain referral evaluation. Despite its simplicity when compared to previously validated tools (STOP-BANG and NoSAS), the instrument exhibits similar performance characteristics.

Tuberculose e tabagismo / Tuberculosis and Smoking

Estima-se que 1,3 bilhão de pessoas no mundo consuma tabaco, e a maioria desses indivíduos está em países subdesenvolvidos ou em desenvolvimento, onde as taxas de tuberculose também são mais elevadas. Algumas revisões sistemáticas e meta-análises de estudos observacionais têm apontado uma associação desfavorável entre as epidemias globais de tuberculose e o tabagismo, nas quais a exposição à fumaça do tabaco está associada com infecção, doença e mortalidade por tuberculose. As bases fisiopatológicas nas quais o tabagismo aumenta o risco de tuberculose são explicadas pela disfunção da mecânica ciliar, diminuição da resposta imune e defeitos na resposta imunológica dos macrófagos, aumentando a suscetibilidade à infecção pelo Mycobacterium tuberculosis. Apesar dos níveis de evidências da associação entre tabagismo e tuberculose, as principais diretrizes mundiais sobre tuberculose trazem pouca informação sobre a necessidade do combate ao tabagismo para o melhor controle da tuberculose. Na prática clínica diária, três ações principais devem ser instituídas: a busca ativa de casos de tuberculose em pacientes tabagistas, a promoção do tratamento da dependência ao tabaco para os pacientes com tuberculose e que o local onde esse tipo de doente recebe assistência e tratamento seja um ambiente livre do tabaco

It is estimated that, worldwide, 1.3 billion people are tobacco consumers, and the majority of these people are in underdeveloped or developing countries, where tuberculosis rates are also elevated. Some systematic reviews and meta-analyses of observational studies have indicated an unfavorable association between the global tuberculosis epidemic and smoking, in which exposure to tobacco smoke is associated with infection, disease, and tuberculosis-related mortality. The pathophysiological mechanisms by which smoking increases the risk of tuberculosis are explained by reduced mucociliary clearance, impaired overall immune response, and defects in the macrophage immune response, all of which increase susceptibility to infection with Mycobacterium Tuberculosis. Despite the overwhelming evidence of the association between smoking and tuberculosis, the main international guidelines on tuberculosis contain too little information about the need to battle smoking in order to achieve better control of tuberculosis. In daily clinical practice, three principal measures must be implemented: engage in active surveillance for tuberculosis cases among smoking patients; promote nicotine dependence treatment for patients with tuberculosis; and convert all facilities at which tuberculosis patients are counseled and treated into smoke-free environments

Sequence analysis of NAT2 gene in Brazilians: identification of undescribed single nucleotide polymorphisms and molecular modeling of the N-acetyltransferase 2 protein structure.

N-Acetyltransferase 2 (NAT2) metabolizes a variety of xenobiotics that includes many drugs, chemicals and carcinogens. This enzyme is genetically variable in human populations and polymorphisms in the NAT2 gene have been associated with drug toxicity and efficacy as well as cancer susceptibility. Here, we have focused on the identification of NAT2 variants in Brazilian individuals from two different regions, Rio de Janeiro and Goiás, by direct sequencing, and on the characterization of new haplotypes after cloning and re-sequencing. Upon analysis of DNA samples from 404 individuals, six new SNPs (c.29T>C, c.152G>T, c.203G>A, c.228C>T, c.458C>T and c.600A>G) and seven new NAT2 alleles were identified with different frequencies in Rio de Janeiro and Goiás. All new SNPs were found as singletons (observed only once in 808 genes) and were confirmed by three independent technical replicates. Molecular modeling and structural analysis suggested that p.Gly51Val variant may have an important effect on substrate recognition by NAT2. We also observed that amino acid change p.Cys68Tyr would affect acetylating activity due to the resulting geometric restrictions and incompatibility of the functional group in the Tyr side chain with the admitted chemical mechanism for catalysis by NATs. Moreover, other variants, such like p.Thr153Ile, p.Thr193Met, p.Pro228Leu and p.Val280Met, may lead to the presence of hydrophobic residues on NAT2 surface involved in protein aggregation and/or targeted degradation. Finally, the new alleles NAT2*6H and NAT2*5N, which showed the highest frequency in the Brazilian populations considered in this study, may code for a slow activity. Functional studies are needed to clarify the mechanisms by which new SNPs interfere with acetylation.

Tuberculosis risk among nursing professionals from Central Brazil.

BACKGROUND: Health care workers (HCWs), mainly those involved in direct contact with tuberculosis (TB) patients, such as nurses, are at high risk for Mycobacterium tuberculosis infection. METHODS: During 2001, 128 nursing professionals from an infectious disease referral hospital in Central Brazil were interviewed and underwent a 2-step tuberculin skin test (TST). Afterwards, individuals with negative TSTs were retested annually to determine the incidence density of TST conversion. RESULTS: TST positivity was detected in 69.5% of the nursing professionals. Length of professional activity and previous direct contact with TB sputum smear-positive patients were associated with tuberculin positivity (P < .05). During the follow-up period, an incidence density of 11.5 new TST conversions per 100 person-years was detected. Two individuals developed extrapulmonary tuberculosis. CONCLUSIONS: The present findings highlight the importance of M tuberculosis infection in HCWs, such as nurses, who are in direct contact with TB patients and ratify the necessity of infection control measures to prevent this infection in health care facilities.

Role of IFN-gamma +874 T/A single nucleotide polymorphism in the tuberculosis outcome among Brazilians subjects.

Several genetic cytokine gene variants have been associated with host susceptibility to infectious diseases, including tuberculosis. Based upon the importance of IFN-gamma in protective immunity against Mycobacterium tuberculosis, and the functional role of the IFN-gamma + 874T/A single nucleotide polymorphism in IFN-gamma production, we genotyped 93 Brazilian tuberculosis patients and 266 asymptomatic health care workers, including 150 individuals with a positive tuberculin skin test, and analyzed the possible association of the +874A low IFN-gamma producer allele with tuberculosis occurrence. Using multivariable logistic regression models, genotype and allele frequencies of the mutant + 874A (low IFN-gamma producer) allele were significantly associated with tuberculosis disease. Heterozygous carriers had a 25% increased chance, while individuals presenting the A/A homozygous genotype had an over two-fold risk of having active tuberculosis (95% CI, 1.16-5.91, P = 0.03). Despite the mixed ethnicity observed in Brazilian populations, the present data agree with observations reported in other populations and thus demonstrate that the functional +874T/A IFN-gamma gene polymorphism is associated with tuberculosis in different populations.

Genetic profile of the arylamine N-acetyltransferase 2 coding gene among individuals from two different regions of Brazil.

Arylamine N-acetyltranferase 2 is the main enzyme responsible for the isoniazid metabolization into hepatotoxic intermediates and the degree of hepatotoxicity severity has been attributed to genetic variability in the NAT2 gene. The main goal of this study was to describe the genetic profile of the NAT2 gene in individuals from two different regions of Brazil: Rio de Janeiro and Goiás States. Therefore, after preparation of DNA samples from 404 individuals, genotyping of the coding region of NAT2 was performed by direct PCR sequencing. Thirteen previously described SNPs were detected in these Brazilian populations, from which seven: 191 G>A; 282 C>T; 341 T>C; 481 C>T; 590 G>A; 803 A>G and 857 G>A are the most frequent in other populations. The presence of so-called ethnic-specific SNPs in our population is in accordance with the Brazilians' multiple ancestry. Upon allele and genotype analysis, the most frequent NAT2 alleles were respectively NAT2*5B (33%), NAT2*6A (26%) and NAT2*4 (20%) being NAT2*5/*5 the more prevalent genotype (31.7%). These results clearly demonstrate the predominance in the studied Brazilian groups of NAT2 alleles associated with slow over the fast and intermediate acetylator genotypes. Additionally, in Rio de Janeiro, a significantly higher frequency of intermediate acetylation status was found when compared to Goiás (42.5% versus 25%) (p=0.05), demonstrating that different regions of a country with a population characterized by a multi-ethnic ancestry may present a large degree of variability in NAT2 allelic frequencies. This finding has implications in the determination of nationwide policies for use of appropriate anti-TB drugs.