Biomedical subjects

N F Schlecht

Publications and source records attributed to N F Schlecht.

9 recordsLinked to original sources

PubMed2006

Classification of DNA methylation patterns in tumor cell genomes using a CpG island microarray.

Our group has initiated experiments to epigenetically profile CpG island hypermethylation in genomic DNA from tissue specimens of head and neck squamous cell carcinoma (HNSCC) using a microarray of 12,288 CpG island clones. Our technique, known as a methylation-specific restriction enzyme (MSRE) analysis, is a variation of the differential methylation hybridization (DMH) technique, in that it is not an array comparison of two DNA samples using methylation-specific restriction enzymes. Instead, it is a comparison of a single DNA sample's response to a methylation-sensitive restriction enzyme (HpaII) and its corresponding methylation-insensitive isoschizomer (MspI). Estimation of the reproducibility of this microarray assay by intraclass correlation (ICC) demonstrated that in four replicate experiments for three tumor specimens, the ICC observed for a given tumor specimen ranged from 0.68 to 0.85 without filtering of data. Repeated assays achieved 87% concordance or greater for all tumors after filtering of array data by fluorescence intensity. We utilized hierarchical clustering on a population of 37 HNSCC samples to cluster tumor samples with similar DNA methylation profiles. Supervised learning techniques are now being utilized to allow us to identify associations between specific epigenetic signatures and clinical parameters. Such techniques will allow us to identify select groups of CpG island loci that could be used as epigenetic markers for both diagnosis and prognosis in HNSCC.

Blotting, Southern↗

PubMed2005

Dyspnea as clinical indicator in patients with chronic obstructive pulmonary disease.

The aim of this study was to evaluate the relationship between dyspnea and functional, psychosocial and quality of life parameters among persons with chronic obstructive pulmonary disease (COPD). We conducted a cross-sectional study of 90 stable COPD patients recruited from a specialized respiratory clinic. Dyspnea was measured using the ATS-DLD-78 questionnaire modified dyspnea scale (1-5 scale). Physical and functional evaluation included spirometry and six minute walking tests. Subjects then completed five psychological questionnaires: the Coping Inventory for Stressful Situations, the State/Trait Anxiety Inventory, the Beck Depression Index, the NEO-Five Factor Personality Inventory, and the Interpersonal Relationships Inventory. Patients also completed two disease-specific health-related quality of life (HRQL) questionnaires: St. George's Respiratory Questionnaire (SGRQ) and Chronic Respiratory Questionnaire (CRQ). Subjects were predominantly male (n = 65) with a mean age of 68 years (+/- standard deviation 7.6). Over half (54%) the patients reported severe dyspnea (grade 5), and a quarter (24%) reported moderate dyspnea (grade 3-4). Mean FEV1 was 37.8 +/- 14.8% predicted. The mean total SGRQ score was 49 +/- 16 and the CRQ total score was 4.2 +/- 0.9. Dyspnea severity was associated with poorer HRQL scores and decreased physical performance. Based on linear regression, dyspnea scores--but not spirometric values--also correlated with indices of anxiety, depression, and neuroticism. Dyspnea correlated more strongly with HRQL and with indices of anxiety and depression than spirometric values. Although spirometry is often used to evaluate disease severity, dyspnea which is a patient centered outcome better reflect overall disease impact among COPD patients.

Aged↗

PubMed2001

Persistent human papillomavirus infection as a predictor of cervical intraepithelial neoplasia.

CONTEXT: Human papillomavirus (HPV) infection is believed to be the central cause of cervical cancer, although most of the epidemiological evidence has come from retrospective, case-control studies, which do not provide information on the dynamics of cumulative or persistent exposure to HPV infection. OBJECTIVE: To assess the risks of cervical neoplasia related to prior persistent HPV infections. DESIGN AND SETTING: Longitudinal study of the natural history of HPV infection and cervical neoplasia in women residing in the city of São Paulo, Brazil, which was conducted between November 1993 and March 1997 and involved repeated measurements of HPV and lesions with follow-up until June 2000. PARTICIPANTS: A total of 1611 women with no cytological lesions at enrollment and HPV test results available from the first 2 visits. MAIN OUTCOME MEASURE: Cervical specimens taken for Papanicolaou cytology and HPV testing every 4 months in the first year and twice yearly thereafter. Incident cervical cancer precursor lesions ascertained by expert review of all cytology smears. RESULTS: The incidence rate of squamous intraepithelial lesions (SILs) was 0.73 per 1000 women-months (95% confidence interval [CI], 0.5-0.9) among women free of HPV at the 2 initial visits and 8.68 (95% CI, 2.3-15.1) among women with HPV type 16 or 18 infections persisting over both visits. Relative to those negative for HPV oncogenic types at both initial visits, the relative risk (RR) of incident SIL was 10.19 (95% CI, 5.9-17.6) for persistent infections with any known oncogenic HPV types. The equivalent RR of incident high-grade SIL was 11.67 (95% CI, 4.1-33.3). The RRs of lesions were considerably higher for persistent infections with HPV type 16 or 18. CONCLUSION: A strong relationship exists between persistent HPV infections and SIL incidence, particularly for HPV types 16 and 18.

Adult↗

PubMed2001

Effect of type of alcoholic beverage on the risks of upper aerodigestive tract cancers in Brazil.

OBJECTIVES: We investigated the effects of alcohol consumption on the risk of cancers of the upper aerodigestive tract (UADT) in a hospital-based case-control study in Brazil. METHODS: A total of 784 cases of cancers of the mouth, pharynx, and larynx and 1578 non-cancer controls matched on age, gender, hospital area, and admission period provided information on alcohol drinking, smoking, and other characteristics via interview. Using logistic regression, we evaluated the relative risks (RR) of UADT cancer for different beverage types based on cumulative ethanol content exposure and frequency of consumption. RESULTS: Relative to nondrinkers of any alcohol, risks of UADT cancers varied across sites both with increased exposure to ethanol and by alcohol type. RRs at equivalent levels of ethanol consumption were highest for cancers of the mouth for hard liquor (6.9 for > 100 kg lifetime consumption, 95% confidence interval (CI) = 2.8-17.1) and cachaça (4.5 for 101-500 kg, 95% CI = 2.2-9.0). Although RRs increased with frequency of drinks per week, when evaluated against higher proportional alcohol intake, reductions in risk were observed for beer and wine. CONCLUSION: Although methods of measurement can influence the interpretation of the carcinogenic nature of alcohols, increased RRs persisted with continued exposure for all types.

Alcohol Drinking↗

PubMed2001

Repeatability of sexual history in longitudinal studies on HPV infection and cervical neoplasia: determinants of reporting error at follow-up interviews.

BACKGROUND: Misclassification of sexual history due to faulty recall or reporting bias may be the reason for variability in the association between sexual history and human papillomavirus (HPV) infection seen in studies conducted in different geographical areas. This study aimed to assess the repeatability of questionnaire information on sexual-history variables and their correlates, using information from repeat interviews by six international prospective cohort studies. METHODS: The pooled dataset included over 14 775 women interviewed on two separate occasions, of whom 5690 returned for a third interview. At each return visit women were re-asked questions on age at first intercourse and number of sexual partners. The six cohorts originated from studies in Denmark, Costa Rica. San Francisco, Toronto, Montreal and São Paulo. RESULTS: Exact agreement between age at first intercourse recalled on separate occasions ranged from 60-85%, whereas exact recall rates for number of sexual partners were substantially lower and more study-dependent, varying between 20% and 77%. The intraclass correlation coefficients gauging the degree of repeatability in responses ranged from 0.68 to 0.97 for age at first intercourse and 0.08 to 0.94 for number of sexual partners. Age, ethnicity, education and cohort membership were the strongest predictors of reporting error for both sexual history markers, although study design characteristics also seemed to play a role. HPV infection status seemed to influence recall of number of partners, but not age at first intercourse. CONCLUSIONS: Information on sexual behaviours is not reliably collected in epidemiological studies of sexually transmitted diseases, which may influence the magnitude of relative risk estimates.

Adolescent↗

PubMed2001

Oncogenic human papillomavirus infection and cervical lesions in aboriginal women of Nunavut, Canada.

BACKGROUND: The high rate of cervical cancer among aboriginal women of northern Canada has prompted the search for more aggressive methods to augment Papanicolaou (Pap) screening in this population. Nearly all cervical cancers result from oncogenic human papillomavirus (HPV) infections. This has generated interest for incorporating HPV testing into the current screening program. GOALS: To determine the prevalence of oncogenic HPVs in Nunavut, and to assess the association between HPV and squamous intraepithelial lesions (SIL). STUDY DESIGN: A cross-sectional study was conducted on the Pap-screened populations in 19 communities of Nunavut, Canada. Liquid-based cytology was used to screen for SIL. HPV testing was performed using the Hybrid Capture II assay. Correlates of HPV infection and SIL were assessed by logistic regression with control for potential confounders. RESULTS: In 1290 women ages 13 to 79 years, the prevalence rate was 26% for oncogenic HPV and 6.9% for SIL. The odds ratio for the association between HPV and SIL was 37.9 (95% CI, 17.7-80.8) after multivariate adjustment. This association increased markedly with increasing viral load. More than 90% of the women with squamous intraepithelial lesions had positive test results for HPV. More than 75% of the women who had positive test results for HPV but negative test results for SIL were younger than 30 years. CONCLUSION: The results of this study form the basis for further evaluation of the role that liquid-based cytology and HPV testing plays and will contribute to the strategy for cervical cancer prevention in Nunavut.

Adolescent↗

PubMed2000

Major histocompatibility complex class II polymorphisms and risk of cervical cancer and human papillomavirus infection in Brazilian women.

Infection with high-risk human papillomavirus (HPV) is the major risk factor for the development of malignant lesions in the uterine cervix. Environmental, behavioral, and ill-defined genetic factors also have been implicated in the pathogenesis of this disease. Associations between human leukocyte antigens (HLAs) and cervical cancer, precursor lesions, and HPV infections have been reported in several populations. To verify whether HLA-DRB1, -DQA1, and -DQB1 diversity is related to cervical cancer in the Brazilian population, 161 cases and 257 controls were HLA typed. Variants of DQA1 and DQB1 promoter regions were also typed in 92 cases and 228 controls. Polymorphism in HLA genes and promoters was distinguished by PCR-based methods, and the magnitude of associations was determined by logistic regression analysis. DRB1*15 [confounder-adjusted odds ratio (OR), 2.24; 95% confidence interval (CI), 1.29-3.90], DRB1*1503 (OR, 2.52; 95% CI, 1.16-5.48), and haplotype DRB1*15-DQB1*0602 (OR, 2.04; 95% CI, 1.15-3.61) were positively associated with cervical cancer. When we considered only DR15 haplotypes that did not carry the DQB1*0602 allele, the risk attributed to DRB1*15 more than doubled. A negative association was found between DQB1*05 and cervical cancer (OR, 0.57; 95% CI, 0.35-0.92), and similar trends were observed for DQA1*0101/04, DRB1*0101, and DRB1*1302. HPV positivity among controls was associated with DRB1*1503 (OR, 4.60; 95% CI, 1.33-15.9), DRB1*0405 (OR, 6.21; 95% CI, 1.66-23.2), and DQB1*0602 (OR, 2.48; 95% CI, 1.06-5.80). We suggest that HLA class II polymorphisms are involved in genetic susceptibility to cervical cancer and HPV infection in a Brazilian population from an area with a high incidence of this neoplasia.

Adolescent↗

PubMed1999

Interaction between tobacco and alcohol consumption and the risk of cancers of the upper aero-digestive tract in Brazil.

The authors investigated the joint effects of tobacco and alcohol consumption on the risk of squamous cell carcinomas of the upper aero-digestive tract (UADT) using data from a hospital-based case-control study conducted in southern Brazil, 1986-1989. A total of 784 cases of cancers of the mouth, pharynx, and larynx and 1,578 non-cancer controls matched on age, sex, hospital catchment area, and period of admission were interviewed about their smoking and drinking habits and other characteristics. Using logistic regression, evidence was found for interaction between the cumulative exposures for smoking and alcohol on UADT cancer risk. The joint effects for pharyngeal cancers exceeded the levels expected under a multiplicative model for moderate smokers (p = 0.007). There was little statistical evidence, however, for interaction on cancers of the mouth (p = 0.28) or larynx (p = 0.95). Among never smokers, heavy drinkers had 9.2 times (95% confidence interval 1.7, 48.5) greater risk of cancers of mouth, pharynx, and supraglottis than never drinkers, with a dose-response trend (p = 0.013) with cumulative consumption. The authors conclude that the interaction occurring in the pharynx between smoking and alcohol on UADT cancers is not uniform, with varying effects depending on the level of smoking exposure. Alcohol may act as both a promoter for tobacco and as an independent risk factor.

Alcohol Drinking↗

PubMed1999

Effect of smoking cessation and tobacco type on the risk of cancers of the upper aero-digestive tract in Brazil.

Tobacco smoking has long been identified as the most important risk factor for upper aero-digestive tract cancers. To investigate the effect of different tobacco types and the benefit of smoking cessation, we analyzed data from a case-control study of 784 cases of mouth, pharynx, and larynx cancers and 1,578 non-cancer controls in three metropolitan hospital areas in Brazil. Subjects were interviewed as to their smoking and drinking habits, demographics, environmental exposures, occupational history, health characteristics, and diet. Controlling for total tobacco and alcohol consumption, risks for ex-smokers compared with current smokers decreased substantially with time since cessation of the habit. Compared with never smokers, ex-smokers of >20 years had a relative risk (RR) of 1.98 [95% confidence interval (CI) = 1.0-3.8] for all upper aerodigestive tract cancers. RRs for long-term (>20 years) ex-smokers tended to be lower for mouth (RR = 1.61) and pharynx (RR = 1.52) than for larynx (RR = 3.63) cancers. The benefit of quitting was strongest for commercial cigarettes (RR = 1.45, 95% CI = 0.7-3.0) for ex-smokers of >10 years, as compared with smoking of black tobacco (RR = 2.57, 95% CI = 1.4-4.6), cigars (RR = 2.59, 95% CI = 0.6-11.6), and pipe tobacco (RR = 3.40, 95% CI = 1.3-8.8).

Brazil↗