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Biomedical subjects

Grace K LeMasters

Publications and source records attributed to Grace K LeMasters.

13 recordsLinked to original sources
PubMed2006

The genetic and environmental factors involved in benzidine metabolism and bladder carcinogenesis in exposed workers.

Genetic susceptibility to bladder cancer in individuals exposed to arylamines may be explained by interindividual metabolic differences that lead to arylamine bioactivation or detoxification. In this article, occupational bladder cancer risk factors and the evidence that links benzidine exposure to bladder cancer are reviewed. Benzidine metabolism is described and compared with that of other aromatic amines. Metabolic polymorphisms and bladder cancer in the context of occupational exposure to aromatic amines are also reviewed, and the environmental and genetic relationships of benzidine exposure and genetic susceptibility are outlined. Only a few studies of bladder cancer genetic susceptibility in populations exposed occupationally to arylamines have been published. The results of these case-control studies show conflicting results, reflecting metabolic differences between monoarylamines and diarylamines such as benzidine. Additional studies and pooled analyses of existing data are needed to establish if individuals are at higher risk of bladder cancer given the presence of certain alleles that make them more susceptible to this disease.

Acetyltransferases↗
PubMed2006

Estimating sampling frequency in pollen exposure assessment over time.

A time series model was fitted to the pollen concentration data collected in the Greater Cincinnati area for the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS). A traditional time series analysis and temporal variogram approach were applied to the regularly spaced databases (collected in 2003) and irregularly spaced ones (collected in 2002), respectively. The aim was to evaluate the effect of the sampling frequency on the sampling precision in terms of inverse of standard error of the overall level of mean value across time. The presence of high autocorrelation in the data was confirmed and indicated some degree of temporal redundancy in the pollen concentration data. Therefore, it was suggested that sampling frequency could be reduced from once a day to once every several days without a major loss of sampling precision of the overall mean over time. Considering the trade-offs between sampling frequency and the possibility of sampling bias increasing with larger sampling interval, we recommend that the sampling interval should take values from 3 to 5 days for the pollen monitoring program, if the goal is to track the long-term average.

Air Pollution↗
PubMed2006

NAT2 slow acetylation and bladder cancer in workers exposed to benzidine.

This study expands a previous study of NAT2 polymorphisms and bladder cancer in male subjects occupationally exposed only to benzidine. The combined analysis of 68 cases and 107 controls from a cohort of production workers in China exposed to benzidine included 30 new cases and 67 controls not previously studied. NAT2 enzymatic activity phenotype was characterized by measuring urinary caffeine metabolite ratios. PCR-based methods identified genotypes for NAT2, NAT1 and GSTM1. NAT2 phenotype and genotype data were consistent. A protective association was observed for the slow NAT2 genotype (bladder cancer OR = 0.3; 95% CI = 0.1 = 1.0) after adjustment for cumulative benzidine exposure and lifetime smoking. Individuals carrying NAT1wt/*10 and NAT1*10/*10 showed higher relative risks of bladder cancer (OR = 2.8, 95% CI = 0.8-10.1 and OR = 2.2, 95% CI = 0.6-8.3, respectively). No association was found between GSTM1 null and bladder cancer. A metaanalysis risk estimate of case-control studies of NAT2 acetylation and bladder cancer in Asian populations without occupational arylamine exposures showed an increased risk for slow acetylators. The lower limit of the confidence interval (OR = 1.4; 95% CI = 1.0-2.0) approximated the upper confidence interval for the estimate obtained in our analysis. These results support the earlier finding of a protective association between slow acetylation and bladder cancer in benzidine-exposed workers, in contrast to its established link as a risk factor for bladder cancer in people exposed to 2-naphthylamine and 4-aminobiphenyl. Study findings suggest the existence of key differences in the metabolism of mono- and diarylamines.

Acetylation↗
PubMed2006

High prevalence of aeroallergen sensitization among infants of atopic parents.

OBJECTIVE: To present methodology to identify atopic parents and determine the prevalence of sensitization to 15 aeroallergens in their infant offspring. STUDY DESIGN: A birth cohort of infants was identified from birth records; an infant was enrolled if 1 of the parents reported allergy respiratory symptoms and had a positive skin prick test (SPT) to a common aeroallergen. At age 1 year, these infants were tested to the same aeroallergens. RESULTS: Of the 680 enrolled infants, 28.4% were SPT+ to 1 or more aeroallergens and/or food, and 18.0% were positive to 1 or more aeroallergens. By category of allergens, 9.7% were sensitized to pollens, 7.5% to molds, 4.3% to house dust mite and/or cockroach, and 3.4% to dog and/or cat. Of the infants who were positive to an aeroallergen, 65.7% remained positive at age 2 years. CONCLUSIONS: Infants born to atopic parents with percutaneous sensitization to aeroallergens are at increased risk for aeroallergen sensitization during infancy, which persists to age 2 years. These findings suggest that current clinical practices, which generally avoid skin testing before age 2 years, be reassessed in this population of high-risk children.

Allergens↗
PubMed2006

Cancer risk among firefighters: a review and meta-analysis of 32 studies.

OBJECTIVE: The objective of this study was to review 32 studies on firefighters and to quantitatively and qualitatively determine the cancer risk using a meta-analysis. METHODS: A comprehensive search of computerized databases and bibliographies from identified articles was performed. Three criteria used to assess the probable, possible, or unlikely risk for 21 cancers included pattern of meta-relative risks, study type, and heterogeneity testing. RESULTS: The findings indicated that firefighters had a probable cancer risk for multiple myeloma with a summary risk estimate (SRE) of 1.53 and 95% confidence interval (CI) of 1.21-1.94, non-Hodgkin lymphoma (SRE = 1.51, 95% CI = 1.31-1.73), and prostate (SRE = 1.28; 95% CI = 1.15-1.43). Testicular cancer was upgraded to probable because it had the highest summary risk estimate (SRE = 2.02; 95% CI = 1.30-3.13). Eight additional cancers were listed as having a "possible" association with firefighting. CONCLUSIONS: Our results confirm previous findings of an elevated metarelative risk for multiple myeloma among firefighters. In addition, a probable association with non-Hodgkin lymphoma, prostate, and testicular cancer was demonstrated.

Case-Control Studies↗
PubMed2006

Environmental risk factors of rhinitis in early infancy.

Previous studies of allergic rhinitis in children have not documented the environmental risk factors for infants at age one. We examined the relationship of environmental tobacco smoke (ETS) and visible mold exposures on the development of allergic rhinitis, rhinitis and upper respiratory infection (URI) in a birth cohort where at least one parent was skin prick test (SPT) positive. ETS exposure and upper respiratory symptoms were obtained by questionnaires. Visible mold was classified as none, low or high during home visit. Infants had a SPT at age one. After adjustment for potential confounders, exposure to >20 cigarettes per day was associated with an increased risk of developing allergic rhinitis at age one [odds ratio (OR)=2.7; 95% CI 1.04-6.8] and rhinitis symptoms during the first year (OR=1.9; 95% CI 1.1-3.2). Infants with low (OR=1.5; 95% CI 1.1-2.3) or high (OR=5.1; 95% CI 2.2-12.1) levels of visible mold in their homes were more likely to have more frequent URI during the first year. Older siblings were protective for development of both rhinitis symptoms and allergic rhinitis. This study suggests that ETS exposure, rather than visible mold, is associated with rhinitis and allergic rhinitis in infants. The analysis also suggests that mold may be a stronger risk factor for URI that ETS.

Causality↗
PubMed2005

Effects of concurrent noise and jet fuel exposure on hearing loss.

UNLABELLED: We sought to examine the effects of occupational exposure to jet fuel on hearing in military workers. METHODS: Noise-exposed subjects, with or without jet fuel exposure, underwent hearing tests. Work histories, recreational exposures, protective equipment, medical histories, alcohol, smoking, and demographics were collected by questionnaire. Jet fuel, solvent, and noise exposure data were collected from records. Fuel exposure estimates were less than 34% of the OSHA Threshold Limit Values. RESULTS: Subjects with 3 years of jet fuel exposure had a 70% increase in adjusted odds of hearing loss (OR = 1.7; 95% CI = 1.14-2.53) and the odds increased to 2.41 (95% CI = 1.04-5.57) for 12 years of noise and fuel exposure. CONCLUSIONS: These findings suggest that jet fuel has a toxic affect on the auditory system.

Adult↗
PubMed2004

Changes in caffeine consumption as a signal of pregnancy.

OBJECTIVES: The purpose of this prospective study was to examine caffeine consumption and other signals of early pregnancy. STUDY DESIGN: One hundred and five pregnant, nonsmoking, coffee drinkers ages 18-40 were enrolled by the ninth week after their last menstrual period (LMP). Participants kept daily diaries of beverage and caffeine consumption and symptoms. Urine samples were collected to assess hormone metabolites. Descriptive statistics were generated. RESULTS: During the first trimester, 96% of subjects decreased or quit drinking coffee, 65% of whom reported a unique aversion to coffee. The mean daily caffeine consumption at LMP from coffee alone was 119 mg (S.D., 105), with a range 1-574 mg. There was a 59% decrease of mean daily consumption of caffeine from coffee between weeks 4 and 6, from 96 to 39 mg. The vast majority of subjects experienced nausea (98%) and appetite loss (93%); vomiting was less prevalent (54%). The most common dietary aversions included meat, coffee, spicy foods, and dairy products. Hormone metabolite patterns are reported. CONCLUSION: Signals of early pregnancy included an aversion to coffee in addition to nausea and vomiting, which resulted in decreased caffeine consumption. These symptoms often interfered with daily life and lasted beyond the first trimester for many. Consideration should be given that a decrease in caffeine consumption may be a signal for a healthy pregnancy and acting as a confounder.

Adolescent↗
PubMed2003

Pulmonary deposition modeling with airborne fiber exposure data: a study of workers manufacturing refractory ceramic fibers.

Increasing production of refractory ceramic fiber (RCF), a synthetic vitreous material with industrial applications (e.g., kiln insulation), has created interest in potential respiratory effects of exposure to airborne fibers during manufacturing. An ongoing study of RCF manufacturing workers in the United States has indicated an association between cumulative fiber exposure and pleural plaques. Fiber sizing data, obtained from electron microscopy analyses of 118 air samples collected in three independent studies over a 20-year period (1976-1995), were used with a computer deposition model to estimate pulmonary dose of fibers of specified dimensions for 652 former and current RCF production workers. Separate dose correction factors reflecting differences in fiber dimensions in six uniform job title groups were used with data on airborne fiber concentration and employment duration to calculate cumulative dose estimates for each worker. From review of the literature, critical dimensions (diameter <0.4 microm, length <10 microm) were defined for fibers that may translocate to the parietal pleura. Each of three continuous exposure/dose metrics analyzed in separate logistic regression models was significantly related to plaques, even after adjusting for possible past asbestos exposure: cumulative fiber exposure, chi(2) = 15.2 (p < 0.01); cumulative pulmonary dose (all fibers), chi(2) = 14.6 (p < 0.01); cumulative pulmonary dose (critical dimension fibers), chi(2) = 12.4 (p < 0.01). Odds ratios (ORs) were calculated for levels of each metric. Increasing ORs were statistically significant for the two highest dose levels of critical dimension fibers (level three, OR = 11, 95%CI = [1.4, 98]; level four, OR = 25, 95%CI = [3.2, 190]). Similar associations existed for all metrics after adjustment for possible asbestos exposure. It was concluded that development of pleural plaques follows exposure- and dose-response patterns, and that airborne fibers in RCF manufacturing facilities include those with critical dimensions associated with pleural plaque formation. Analysis of additional air samples may improve estimates of the dose-response relationship.

Air Pollutants, Occupational↗
PubMed2002

Pregnancy hormone metabolite patterns, pregnancy symptoms, and coffee consumption.

Because of contradictory reports of pregnancy outcomes and coffee intake, this study was designed to determine how hormone metabolite levels, symptoms, and coffee consumption patterns are related. Eligible subjects were recruited in Cincinnati, Ohio, from 1996 to 1998, aged 18-40 years, and nonsmokers; drank at least 18 ounces (1 ounce = 29.6 ml) of coffee per week (including decaffeinated) at the last menstrual period; and were enrolled by 9 weeks from the last menstrual period. Beverage consumption and pregnancy symptoms were recorded daily. Weekly, first-morning urine samples were collected to assess human chorionic gonadotropin, estrone-3-glucuronide, and pregnanediol-3-glucuronide. A time-dependent, repeated measures analysis was performed to test several associations. Data from 92 subjects were analyzed with the following results. 1) Coffee consumption was significantly, inversely associated with weekly levels of estrone-3-glucuronide and human chorionic gonadotropin. 2) Weekly hours of nausea were significantly, directly associated with human chorionic gonadotropin and inversely with estrone-3-glucuronide and pregnanediol-3-glucuronide. 3) Weekly coffee consumption was significantly associated with vomiting but not with nausea or appetite loss. 4) Weekly levels of pregnanediol-3-glucuronide were 32.2% lower in subjects who drank at least 8 ounces of coffee/day at the last menstrual period, though above what was necessary to maintain those pregnancies. This study shows the significance of these important variables to be considered in future research.

Adult↗
PubMed2002

A longitudinal study of chest radiographic changes of workers in the refractory ceramic fiber industry.

STUDY OBJECTIVE: This industry-wide longitudinal study examines chest radiographic changes of workers manufacturing refractory ceramic fibers (RCF). DESIGN: Chest radiographs were obtained every 3 years and were interpreted using the 1980 International Labour Organization classification for pneumoconiosis. Three exposure metrics were calculated: duration and latency in a production job, and cumulative exposure (fiber-months per cubic centimeter). PARTICIPANTS: The radiographic survey included 625 current workers at five manufacturing sites and 383 former workers at two of the five sites. MEASUREMENTS AND RESULTS: Pleural changes were seen in 27 workers (2.7%). Of workers with > 20 years of latency from initial production job or 20 years of duration in a production job, 16 workers (8.0%) and 5 workers (8.1%) demonstrated pleural changes, respectively. Results from the cumulative exposure analysis (> 135 fiber-months per cubic centimeter) demonstrated a significant elevated odds ratio (OR) of 6.0 (95% confidence interval [CI], 1.4 to 31.0). The incidence of irregular opacities at profusion categories > or = 1/0 was similar to other nonspecified dust-exposed worker populations at 1.0%, and showed a nonsignificant elevated OR in regard to cumulative fiber exposure of 4.7 (95% CI, 0.97 to 23.5). CONCLUSIONS: RCF are significantly associated with pleural changes that were predominantly pleural plaques, but have not resulted in a statistically significant increase in interstitial changes.

Adult↗