Biomedical subjects

S W Thurston

Publications and source records attributed to S W Thurston.

5 recordsLinked to original sources

PubMed2001

The NAD(P)H:quinone oxidoreductase 1 gene polymorphism and lung cancer: differential susceptibility based on smoking behavior.

We conducted a hospital-based case-control study of 814 lung cancer patients and 1123 controls to examine the association of the NAD(P)H: quinone oxidoreductase 1 (NQO1) gene polymorphism with lung cancer susceptibility. Using PCR-RFLP genotyping assay techniques, we analyzed DNA samples to detect the variant forms of the NQO1 gene in exon 6 on chromosome 16q. We examined the relationship between lung cancer odds and NQO1 genotypes after adjusting for age, gender, and smoking behavior using generalized additive modeling. We found no overall association between NQO1 genotypes and lung cancer susceptibility, regardless of age, gender, family history of cancer, or histological cell type. However, our data demonstrated that in both former and current smokers, there was an association between NQO1 genotypes and lung cancer susceptibility that was dependent upon cigarette smoking duration and smoking intensity. For both current and former smokers, smoking intensity was more important in predicting cancer risk than smoking duration for all of the genotypes. Among former smokers, individuals with the T/T genotype were predicted to have a greater cancer risk than those with the C/C genotype for smoking durations up to 37 years. The predicted cancer risk for former smokers with the C/T versus T/T genotype depended on both smoking intensity and smoking duration. Our results support the concept that differential susceptibility to lung cancer is a function of both an inheritable trait in NQO1 metabolism and individual smoking characteristics.

Adult↗

PubMed2001

The interaction between microsomal epoxide hydrolase polymorphisms and cumulative cigarette smoking in different histological subtypes of lung cancer.

Microsomal epoxide hydrolase (mEH) is involved in the metabolism of environmental and tobacco carcinogens. Smaller studies found inconsistent results in the relationship between mEH polymorphisms and lung cancer risk. We investigated the two polymorphisms of mEH in 974 Caucasian lung cancer patients and 1142 controls using PCR-RFLP techniques. The results were analyzed using generalized additive models and logistic regression, adjusting for relevant covariates. There was no overall relationship between mEH genotypes and lung cancer risk. The adjusted odds ratio (OR) of the very low activity genotype versus that of other genotypes combined was 1.00 [95% confidence interval (CI), 0.74-1.34]. However, gene-environment interaction analyses revealed that the ORs decreased as cumulative smoking (defined as square root of pack-years) increased. When pack-years = 0, the OR was 1.89 (95% CI, 1.08-3.28). When pack-years = 28.5, the OR was 1.00 (95% CI, 0.76-1.32), and when pack-years = 80, the OR decreased to 0.65 (95% CI, 0.42-1.00). When cases were stratified according to histological subtypes, the interaction between mEH genotype and cumulative smoking was statistically significant (P < 0.01) for the 222 squamous cell carcinoma cases, whereas it was not significant (P = 0.18) for the 432 adenocarcinoma cases. In conclusion, cumulative cigarette smoking plays a pivotal role in the association between mEH polymorphisms and lung cancer risk, altering the direction of risk (in the case of the very low activity genotype) from a risk factor in nonsmokers to a relatively protective factor in heavy smokers.

Adult↗

PubMed2000

Petrochemical exposure and menstrual disturbances.

BACKGROUND: An exploratory, cross-sectional retrospective study was conducted to examine the effects of benzene exposure on menstrual problems. METHODS: The study was based on a survey administered to over 3,000 women who worked in a large petrochemical company in Beijing, China. An abnormal menstrual cycle length (AMCL), defined as an average menstrual cycle length of greater than 35 days or less than 21 days, is the major outcome of interest. RESULTS: After 7 years of benzene exposure, the adjusted odds ratio of having AMCL for each additional 5 years of exposure was 1.71 (95% CI 1.27-2.31). Feeling stressed at work was also an important predictor. CONCLUSIONS: This study suggests a significant association of benzene exposure and perceived stress with menstrual disturbance. A prospective study is needed to confirm this finding.

Adult↗

PubMed2000

Negative binomial additive models.

The generalized additive model is extended to handle negative binomial responses. The extension is complicated by the fact that the negative binomial distribution has two parameters and is not in the exponential family. The methodology is applied to data involving DNA adduct counts and smoking variables among ex-smokers with lung cancer. A more detailed investigation is made of the parametric relationship between the number of adducts and years since quitting while retaining a smooth relationship between adducts and the other covariates.

Algorithms↗

PubMed1999

Early age at smoking initiation and tobacco carcinogen DNA damage in the lung.

BACKGROUND: DNA adducts formed as a consequence of exposure to tobacco smoke may be involved in carcinogenesis, and their presence may indicate a high risk of lung cancer. To determine whether DNA adducts can be used as a "dosimeter" for cancer risk, we measured the adduct levels in nontumorous lung tissue and blood mononuclear cells from patients with lung cancer, and we collected data from the patients on their history of smoking. METHODS: We used the 32P-postlabeling assay to measure aromatic hydrophobic DNA adducts in nontumorous lung tissue from 143 patients and in blood mononuclear cells from 54 of these patients. From the smoking histories, we identified exposure variables associated with increased DNA adduct levels by use of multivariate analyses with negative binomial regression models. RESULTS/ CONCLUSIONS: We found statistically significant interactions for variables of current and former smoking and for other smoking variables (e.g., pack-years [number of packs smoked per day x years of smoking] or years smoked), indicating that the impact of smoking variables on DNA adduct levels may be different in current and former smokers. Consequently, our analyses indicate that models for current and former smokers should be considered separately. In current smokers, recent smoking intensity (cigarettes smoked per day) was the most important variable. In former smokers, age at smoking initiation was inversely associated with DNA adduct levels. A highly statistically significant correlation (r=.77 [Spearman's correlation]; two sided P<.001) was observed between DNA adduct levels in blood mononuclear cells and lung tissue. IMPLICATIONS: Our results in former smokers suggest that smoking during adolescence may produce physiologic changes that lead to increased DNA adduct persistence or that young smokers may be markedly susceptible to DNA adduct formation and have higher adduct burdens after they quit smoking than those who started smoking later in life.

Age Factors↗