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Biomedical subjects

J T Bernert

Publications and source records attributed to J T Bernert.

At least 19 recordsLinked to original sources
PubMed2001

Environmental and behavioral predictors of salivary cotinine in Latino tobacco workers.

We report the results of a cohort study of 182 seasonal and migrant farmworkers engaged in tobacco production in two North Carolina counties. Data were collected on tobacco work tasks and risk factors for exposure to nicotine, including smoking, every 2 weeks over a 10-week period during the summer of 1999. Saliva samples were collected for cotinine analysis at every contact. Salivary cotinine levels increased across the season, independent of smoking status. Multivariate analyses identified a model (R2 = 0.68) in which predictors of cotinine included greater age, later-season work, wet working conditions, smoking, and work task. Harvesting ("priming") tobacco was associated with higher cotinine levels than other tasks. This study demonstrates that tobacco workers experience substantial work-related exposure to nicotine. The long-term effects of such exposure should be investigated.

Adult↗
PubMed2000

Effect of counselling mothers on their children's exposure to environmental tobacco smoke: randomised controlled trial.

OBJECTIVE: To test the efficacy of behavioural counselling for smoking mothers in reducing young children's exposure to environmental tobacco smoke. DESIGN: Randomised double blind controlled trial. SETTING: Low income homes in San Diego county, California. PARTICIPANTS: 108 ethnically diverse mothers who exposed their children (aged <4 years) to tobacco smoke in the home. INTERVENTION: Mothers were given seven counselling sessions over three months. MAIN OUTCOME MEASURES: Children's reported exposure to environmental tobacco smoke from mothers in the home and from all sources; children's cotinine concentrations in urine. RESULTS: Mothers' reports of children's exposure to their smoke in the home declined in the counselled group from 27.30 cigarettes/week at baseline, to 4.47 at three months, to 3.66 at 12 months and in the controls from 24.56, to 12.08, to 8.38. The differences between the groups by time were significant (P=0.002). Reported exposure to smoke from all sources showed similar declines, with significant differences between groups by time (P=0.008). At 12 months, the reported exposure in the counselled group was 41.2% that of controls for mothers' smoke (95% confidence interval 34.2% to 48.3%) and was 45.7% (38.4% to 53.0%) that of controls for all sources of smoke. Children's mean urine cotinine concentrations decreased slightly in the counselled group from 10.93 ng/ml at baseline to 10.47 ng/ml at 12 months but increased in the controls from 9.43 ng/ml to 17.47 ng/ml (differences between groups by time P=0.008). At 12 months the cotinine concentration in the counselled group was 55.6% (48.2% to 63.0%) that of controls. CONCLUSIONS: Counselling was effective in reducing children's exposure to environmental tobacco smoke. Similar counselling in medical and social services might protect millions of children from environmental tobacco smoke in their homes.

Adult↗
PubMed2000

Measuring secondhand smoke exposure in babies: the reliability and validity of mother reports in a sample of low-income families.

The reliability and validity of mother's reports of their infants' exposure to secondhand smoke (SHS) were examined in an ethnically diverse sample of low-income, low-education families (N = 141 mothers). At baseline and posttest, smoking mothers reported about their infants' SHS exposure at different locations and by different sources during the previous week. Findings show that mothers can give reliable accounts of the degree to which they contribute to their babies' SHS exposure. Mothers are able to differentiate between their own smoking behavior and the extent to which they expose their infants. Consistent with the overall exposure pattern, exposure caused by the mother and exposure occurring at home showed the strongest associations with biological and environmental measures. These findings suggest that smoking mothers can provide reliable and valid reports of the degree to which their infants are exposed to SHS.

Adult↗
PubMed1999

Measuring environmental tobacco smoke exposure in infants and young children through urine cotinine and memory-based parental reports: empirical findings and discussion.

OBJECTIVE: This study examined the reliability and potential biases of two urine collection methods from which cotinine measures were obtained and the validity of memory-based parental reports of their children's exposure to environmental tobacco smoke (ETS). DESIGN: Structured interviews were conducted with mothers of infants and young children to obtain memory-based estimates of recent ETS exposure. Urine samples were collected through standard and cotton roll collection methods for cotinine analysis. SETTING: All interviews took place at an off-campus research facility. Urine samples were collected at the study office or the subjects' homes. PARTICIPANTS: Mothers were recruited from San Diego county sites of the Women, Infants, and Children (WIC) Supplemental Food and Nutrition Program. Sample 1 (infants) consisted of eight boys and eight girls aged 1-44 months (mean = 12.6 months). Sample 2 (children) included 10 boys and 10 girls aged 3-8 years (mean = 61.2 months). MAIN OUTCOME MEASURES: Urine cotinine and memory-based parent reports of ETS exposure from structured interviews. RESULTS: There was overall high reliability for urine cotinine measures and no effect of collection method on urine cotinine levels. Memory-based reports obtained from smoking mothers showed moderately strong and consistent linear relationships with urine cotinine measures of their infants and children (r = 0.50 to r = 0.63), but not for reports obtained from non-smoking mothers. CONCLUSIONS: Memory-based parental reports of short-term ETS exposure can play an important role in quantifying ETS exposure in infants and children.

Child↗
PubMed1998

Serum fatty acids and the risk of fatal cancer. MRFIT Research Group. Multiple Risk Factor Intervention Trial.

To examine the relation between serum fatty acids and cancer, the authors conducted a nested case-control study of 108 middle-aged men who died of cancer and 215 men without cancer, who were enrolled in the Multiple Risk Factor Intervention Trial (MRFIT) between 1973 and 1976. Control subjects were matched to case subjects on age, smoking status, treatment assignment, date of randomization, and clinical center. After confirming the stability of the stored serum samples, the authors measured serum fatty acid levels by gas-liquid chromatography and analyzed their association with cancer. In stepwise logistic regression analyses that controlled for the MRFIT selection criteria variables and for alcohol consumption, no fatty acid was significantly associated with overall risk of cancer death (all p > 0.05). Serum levels of phospholipid dihomogammalinolenic acid (20:3), an essential fatty acid, were inversely associated with the risk of dying from lung cancer; a standard deviation increase was associated with a 32% decrease in risk (p = 0.05). Dietary cholesterol intake was associated with the risk of nonlung, non-digestive tract cancers; a standard deviation increase (331 mg/day) was associated with a 75% increase in risk (p = 0.02). The authors found no evidence to suggest that increased dietary intake or serum levels of polyunsaturated fatty acids were associated with an increased risk of fatal cancer among middle-aged men at high risk for coronary heart disease. The clinical significance of the inverse association between dihomogammalinolenic acid and lung cancer death is uncertain and requires confirmation.

Biomarkers, Tumor↗
PubMed1998

Exposure of casino employees to environmental tobacco smoke.

Environmental and medical evaluations were performed to evaluate occupational exposure to environmental tobacco smoke (ETS) among casino employees. Air concentrations of both nicotine and respirable dust were similar to those published in the literature for other non-industrial indoor environments. The geometric mean serum cotinine level of the 27 participants who provided serum samples was 1.34 nanograms per milliliter (ng/mL) (pre-shift) and 1.85 ng/mL (post-shift). Both measurements greatly exceeded the geometric mean value of 0.65 ng/mL for participants in the Third National Health and Nutrition Examination Survey (NHANES III) who reported exposure to ETS at work. This evaluation demonstrates that a sample of employees working in a casino gaming area were exposed to ETS at levels greater than those observed in a representative sample of the US population, and that the serum and urine cotinine of these employees increased during the workshift.

Adult↗
PubMed1997

An evaluation of the use of dried blood spots from newborn screening for monitoring the prevalence of cocaine use among childbearing women.

A collaborative March of Dimes study was designed to examine the utility of dried blood spot (DBS) materials routinely collected from newborns as a source for monitoring cocaine exposure and to assess the prevalence of cocaine use among childbearing women in Georgia. We used a modified urinary radioimmunoassay (RIA) to anonymously detect the cocaine metabolite benzoylecgonine (BE) in DBSs. Extensive efforts were undertaken to assure absolute nonlinkage of BE data to any individual. The positive results found by RIA were confirmed by a mass spectrometry (MS) method specifically developed to detect BE in DBSs. BE was measured in 23,141 DBSs collected during 2 months of routine newborn screening in Georgia. A good correlation was observed for RIA results versus MS results (r2 = 0.97). The estimated minimal statewide BE prevalence was 4.8 per 1000 childbearing women. We demonstrated that immunoassay testing for cocaine without confirmatory testing can yield falsely elevated prevalence rates. When proper confirmatory testing is done, DBSs are a valuable source for population-based monitoring of substance abuse among childbearing women.

Blood Specimen Collection↗
PubMed1997

Development and validation of sensitive method for determination of serum cotinine in smokers and nonsmokers by liquid chromatography/atmospheric pressure ionization tandem mass spectrometry.

We describe a sensitive and specific method for measuring cotinine in serum by HPLC coupled to an atmospheric pressure chemical ionization tandem mass spectrometer. This method can analyze 100 samples/day on a routine basis, and its limit of detection of 50 ng/L makes it applicable to the analysis of samples from nonsmokers potentially exposed to environmental tobacco smoke. Analytical accuracy has been demonstrated from the analysis of NIST cotinine standards and from comparative analyses by both the current method and gas chromatography/high-resolution mass spectrometry. Precision has been examined through the repetitive analysis of a series of bench and blind QC materials. This method has been applied to the analysis of cotinine in serum samples collected as part of the Third National Health and Nutrition Examination Survey (NHANES III).

Chromatography, High Pressure Liquid↗
PubMed1996

Relation of smoking and alcohol consumption to serum fatty acids.

To examine the relation of cigarette smoking and alcohol consumption to serum fatty acid levels, the authors conducted a cross-sectional study of 190 men who were enrolled in the Multiple Risk Factor Intervention Trial between 1973 and 1976. After controlling for dietary fat, cholesterol, energy intake, and other potential confounders, the authors found that smoking and alcohol intake were associated with the serum cholesterol ester and phospholipid levels of several fatty acids. As the number of cigarettes smoked per day increased, the levels of cholesterol ester and phospholipid palmitoleic acid (16:1) and oleic acid (18:1) and the levels of phospholipid dihomogammalinolenic acid (20:3) and omega-9 eicosatrienoic acid (20:3) increased (all p's < or = 0.01). Serum levels of phospholipid omega-3 docosahexaenoic acid (22:6) and cholesterol ester and phospholipid arachidonic acid (20:4) were inversely associated with smoking (all p's < or = 0.01). As the number of alcoholic drinks per week increased, levels of cholesterol ester and phospholipid palmitic acid (16:0) and oleic acid (18:1), cholesterol ester myristic acid (14:0), and phospholipid palmitoleic acid (16:1), adrenic acid (22:4), and omega-9 eicosatrienoic acid (20:3) increased (all p's < 0.05), whereas levels of cholesterol ester and phospholipid linoleic acid (18:2) and phospholipid stearic acid (18:0) and the serum polyunsaturated fat: saturated fat ratio decreased (all p's < or = 0.01). These results suggest that smoking and alcohol consumption may influence the absorption, synthesis, or metabolism of serum fatty acids. Studies that use serum fatty acid levels as indicators of dietary fat intake should control for the effects of cigarette smoking and alcohol consumption.

Adult↗
PubMed1996

Exposure of the US population to environmental tobacco smoke: the Third National Health and Nutrition Examination Survey, 1988 to 1991.

OBJECTIVE: To estimate the extent of exposure of the US population to environmental tobacco smoke and the contribution of the home and workplace environment to environmental tobacco smoke exposure. DESIGN: Nationally representative cross-sectional survey including questionnaire information from persons aged 2 months and older (n=16818) and measurements of serum cotinine (a metabolite of nicotine) from persons aged 4 years and older (n=10642). SETTING/PARTICIPANTS: Participants in the Third National Health and Nutrition Examination Survey, October 25, 1988, to October 21, 1991. RESULTS: Of US children aged 2 months to 11 years, 43% lived in a home with at least 1 smoker, and 37% of adult non-tobacco users lived in a home with at least 1 smoker or reported environmental tobacco smoke exposure at work. Serum cotinine levels indicated more widespread exposure to nictoine. Of non-tobacco users, 87.9% had detectable levels of serum cotinine. Both the number of smokers in the household and the hours exposed at work were significantly and independently associated (P<.001, multiple regression t test) with increased serum cotinine levels. Serum cotinine levels of children, non-Hispanic blacks, and males indicated that these groups had higher exposure to environmental tobacco smoke. Dietary variables showed no consistent association with serum cotinine levels, and dietary contribution to serum cotinine level, if any, appeared to be extremely small. CONCLUSIONS: The high proportion of the population with detectable serum cotinine levels indicates widespread exposure to environmental tobacco smoke in the US population. Both the home and workplace environments significantly contribute to environmental tobacco smoke exposure in the United States.

Adolescent↗
PubMed1996

Serum fatty acids and blood pressure.

To examine the relation between serum fatty acids and blood pressure, we conducted a cross-sectional study of 156 men who were enrolled in the Multiple Risk Factor Intervention Trial. After confirming the stability of the stored serum samples, we measured serum fatty acid levels by gas-liquid chromatography and examined their association with blood pressure. Using stepwise linear regression, we determined that each SD increase (1.9%) in the serum level of cholesterol ester palmitoleic acid (16:1) was associated with a systolic pressure increase of 3.3 mm Hg (95% confidence interval, 0.9 to 5.6 mm Hg) and each SD increase (0.1%) in phospholipid omega 9 eicosatrienoic acid (20:3) was associated with a diastolic pressure increase of 1.7 mm Hg (95% confidence interval, 0.5 to 2.9 mm Hg). Serum level of cholesterol ester steric acid (18:0) was inversely associated with diastolic pressure: each SD increase (0.2%) was associated with a decrease of 1.4 mm Hg (95% confidence interval, -2.5 to -0.2 mm Hg). In multivariate models that included dietary fat intake, cholesterol ester dihomogammalinolenic acid (20:3) was also associated with diastolic pressure: each SD increase (0.16%) was associated with an increase of 1.2 mm Hg (95% confidence interval, 0.1 to 2.4 mm Hg). Our results indicate that three nonessential fatty acids--stearic acid, palmitoleic acid, and omega 9 eicosatrienoic acid, and one essential fatty acid--dihomogammalinolenic acid, are independent correlates of blood pressure among middle-aged American men at high risk of coronary heart disease.

Adult↗
PubMed1995

Serum fatty acids and the risk of coronary heart disease.

To examine the relation between serum fatty acids and coronary heart disease (CHD), the authors conducted a nested case-control study of 94 men with incident CHD and 94 men without incident CHD who were enrolled in the Usual Care group of the Multiple Risk Factor Intervention Trial between December 1973 and February 1976. After confirming the stability of the stored serum samples, the authors measured serum fatty acid levels by gas-liquid chromatography and examined their association with CHD. In all multivariate models, levels of the cholesterol ester saturated fatty acid palmitic acid (16:0) were directly associated with CHD risk (standardized odds ratio = 1.68; 95% confidence interval 1.10-2.55 in the model that adjusted for total plasma cholesterol level). Levels of the phospholipid omega-3 fatty acid docosapentaenoic acid (22:5) were inversely associated with CHD risk in the two multivariate models that controlled for the effects of total plasma cholesterol level or high density lipoprotein cholesterol to total plasma cholesterol ratio (standardized odds ratio = 0.58; 95% confidence interval 0.38-0.89 in the first model that controlled for total plasma cholesterol level). In contrast to the first two multivariate models, levels of the docosahexaenoic acid (22:6) were inversely associated with CHD risk in a third multivariate model that controlled for the effects of high density lipoprotein cholesterol to low density lipoprotein cholesterol ratio (standardized odds ratio = 0.57; 95% confidence interval 0.36-0.90). These findings are consistent with other evidence indicating that saturated fatty acids are directly correlated with CHD and that omega-3 polyunsaturated fatty acids are inversely correlated with CHD. Because these associations were present after adjustment for blood lipid levels, other mechanisms, such as a direct effect on blood clotting, may be involved.

Adult↗
PubMed1995

Serum fatty acids and the risk of stroke.

BACKGROUND AND PURPOSE: To examine the relationship between serum fatty acids, which reflect dietary intake, and stroke, we conducted a nested case-control study of 96 men with incident stroke and 96 control subjects matched by age, clinical center, treatment group, and date of randomization who were enrolled in the Multiple Risk Factor Intervention Trial. METHODS: After confirming the stability of the stored serum samples, we measured serum cholesterol ester and phospholipid fatty acid levels as the percentage of total fatty acids by gas-liquid chromatography and examined their association with incident stroke. Using stepwise conditional logistic regression that controlled for risk factors for stroke, we determined which fatty acids were independent correlates of stroke. RESULTS: In univariate models, a standard deviation (SD) increase (1.37%) in phospholipid stearic acid (18:0) was associated with a 37% increase in the risk of stroke, whereas an SD increase (0.06%) in phospholipid omega-3 alpha-linolenic acid (18:3) was associated with a 28% decrease in the risk of stroke (all P < .05). Only alpha-linolenic acid in the cholesterol ester fraction was associated with the risk of stroke in multivariate models: an SD increase (0.13%) in the serum level of alpha-linolenic acid was associated with a 37% decrease in the risk of stroke (P < .05). Systolic blood pressure and cigarette smoking were also independently associated with stroke risk. CONCLUSIONS: Our findings suggest that higher serum levels of the essential fatty acid alpha-linolenic acid are independently associated with a lower risk of stroke in middle-aged men at high risk for cardiovascular disease.

Adult↗
PubMed1994

Technical and scientific developments in exposure marker methodology.

Recent advances in techniques to measure markers of exposure to environmental toxicants in humans are changing the ways in which environmental scientists, epidemiologists, and policymakers characterize and interpret such exposure. In this article we review some major technical and scientific developments in exposure marker methodology for estimating internal dose, with special reference to studies conducted at the US Centers for Disease Control and Prevention. We consider important characteristics of laboratory methods, advances in laboratory technology, analytical standards, and quality assurance of laboratory measurements; comparisons with indirect methods for estimating exposures, such as exposure indices and questionnaires; human pharmacokinetic data; sampling problems; surveillance of human exposures to toxicants; and interpretation of measurements. With a view to increasing the reliability of exposure assessment, we make recommendations for obtaining more data on human exposure to toxicants.

Biomarkers↗
PubMed1992

Determination of "free" glycerol in human serum reference materials by isotope-dilution gas chromatography-mass spectrometry.

Serum free glycerol analyses are an important part of the preparation and evaluation of human serum reference materials used for the quality assurance of triglyceride assays. However, enzymatic kits for free glycerol analysis obtained from different vendors have, on occasion, provided different results for a given sample. In an effort to establish the "target" glycerol content of selected reference materials, we have established a method for the analysis of serum free glycerol by using isotope-dilution gas chromatography-mass spectrometry, incorporating [1,3-13C2]glycerol as the internal standard. The use of a simplified serum extraction and clean-up procedure resulted in (uncorrected) recoveries of glycerol averaging about 90% before derivatization, and in estimated concentrations for spiked serum pools that corresponded closely to the expected values. A comparison of enzymatic and gas chromatographic-mass spectrometric results for several reference serum pools suggest that the latter method is of value in evaluating and validating routine enzymatic methods for free glycerol analysis.

Carbon Isotopes↗
PubMed1991

Manufacturing processes at two French rapeseed oil companies: possible relationships to toxic oil syndrome in Spain.

The toxic oil syndrome (TOS) epidemic that occurred in Spain in spring 1981 has been associated with the consumption of rapeseed oil that was denatured with aniline for industrial use but diverted for human consumption. The precise aetiologic agent in the oil responsible for the outbreak has not been identified. To learn more about possible contaminants and how the contamination might have occurred, we visited two French companies that process rapeseed oil and that were identified in Spanish administrative and judicial records as the ones exporting aniline-denatured rapeseed oil to Spain in 1981. With the apparently full and voluntary co-operation of personnel at both companies, we reviewed the processes involved in manufacturing, treating and transporting rapeseed oil, and we have summarized the information provided to us. Of particular importance is the finding that oil exported to Spain was taken from stock, the rest of which was sold for human consumption in the French domestic market, apparently without any adverse health effects. The differences between the oil exported to Spain and the oil sold as food in France were that aniline equivalent to 2% of the weight of the oil was added to most of the Spanish oil but not to that sold in France, and that contamination of the Spanish oil may have occurred in the tank trucks used for transportation to Spain, which had previously carried industrial chemicals. There is no assurance that the trucks were cleaned appropriately for transporting a food product before the oil was loaded for the journey to Spain. Since the clinical manifestations of TOS are not those of aniline toxicity, we conclude that the aetiological agent of TOS is likely to be one of the following: (1) a contaminant in the aniline, (2) a contaminant introduced during transportation, (3) a reaction product of normal oil components or materials used in refining with either aniline or the potential contaminants mentioned under (1) or (2) above.

Aniline Compounds↗
PubMed1991

Factors influencing the accuracy of the national reference system total cholesterol reference method.

Previous comparisons between the Reference and Definitive Methods for measuring serum cholesterol have demonstrated a small but persistent positive bias in the Reference Method, averaging about +1.6%. Here we describe the results of further investigations designed to better characterize the nature of this bias. Analysis of a well-characterized model serum sample (SRM 909) suggests that more than half of the difference in cholesterol values determined by the two methods is the result of small contributions from cholesterol precursor sterols and phytosterols, which are also measured for the Reference Method. An additional significant contribution may be from cholesterol oxidation products, particularly 7-hydroxycholesterol isomers, which are active in the Liebermann-Burchard reaction. The 7-hydroxycholesterol in SRM 909, most of which appeared to be already present in the serum rather than formed during saponification, may account for as much as 20% of the observed difference between the methods. Contributions from other possible sources, including impurities in the cholesterol standard and incomplete saponification of cholesteryl esters, are very small. Because the observed bias is both quite small and consistent among samples, the cholesterol Reference Method continues to meet all of the requirements generally expected for a dependable and effective Reference Method.

Carbon Isotopes↗