PubMed Health⌕ Search

Biomedical subjects

Ram B Jain

Publications and source records attributed to Ram B Jain.

5 recordsLinked to original sources
PubMed2006

Determination of 14 polycyclic aromatic hydrocarbons in mainstream smoke from U.S. brand and non-U.S. brand cigarettes.

Tobacco smoke contains thousands of chemical compounds, including many carcinogenic polycyclic aromatic hydrocarbons (PAHs). To determine the concentration ranges of PAHs in tobacco smoke and to understand what factors alter their levels, we quantitatively measured 14 PAHs in mainstream smoke from a transnational U.S. brand (Marlboro) and from locally popular brand cigarettes from 14 countries. We used standardized machine smoking conditions (35-mL puff volume, 60-s puff interval, and 2-s puff duration), extraction of total particulate matter from the Cambridge filters, and gas chromatography/mass spectrometry detection. Deliveries of total PAHs in mainstream smoke of local brands were statistically significantly higher (p < 0.01) than Marlboros in seven countries. In four countries, Marlboro cigarettes had mainstream smoke total PAH levels that were statistically significantly higher (p < 0.01) than local brands. In the remaining three countries, the differences in PAH levels were not statistically significant. Under standard machine smoking conditions, PAH levels were negatively correlated with cigarette filter ventilation levels. We found that several local brands containing primarily flue-cured tobacco filler had relatively high mainstream smoke PAH deliveries, in agreement with findings by previous researchers that flue-cured tobacco typically delivers more PAHs than other tobacco types. We also observed that PAHs were inversely correlated with total carcinogenic tobacco-specific nitrosamines and nitrate content, but these correlations were not statistically significant at the 95% confidence interval. The findings suggest that tobacco blend and nitrate levels may influence PAH deliveries, but other factors may confound this relation.

Air Pollutants↗
PubMed2005

Clinical vitamin B6 analysis: an interlaboratory comparison of pyridoxal 5'-phosphate measurements in serum.

BACKGROUND: Recent investigations into the role vitamin B(6) plays in reducing risk of stroke and cardiovascular disease have heightened interest in vitamin B(6) intake and its relationship to clinical status indicators. Because a true reference method and certified reference materials are lacking, little is known about the relative analytical performance of clinical vitamin B(6) assays. METHODS: Ten laboratories experienced in clinical vitamin B(6) analysis participated in a 3-day analysis of 69 serum and 3 aqueous specimens for pyridoxal 5'-phosphate (PLP). Laboratories used either HPLC-based or enzymatic assays. Results were analyzed for imprecision, recovery, and bias relative to consensus means. RESULTS: Among laboratories, mean within-day CVs (3 specimens x 3 measurements/day) were 0.6%-37% and between-day CVs (20 specimens x 1 measurement/day x 3 days) were 1.4%-26%. Mean recoveries of added PLP were 53%-144%, and mean sample pool mixing recoveries were 75%-119%. Consensus means calculated for 20 serum specimens gave mean relative biases between measurement of -10.0% to 24.3% among participating laboratories over a range of 15.8-319 nmol/L PLP. Measurement imprecision and biases were evaluated against empirically derived performance criteria based on biological variation. Three of 10 laboratories met optimum imprecision requirements and had 90% or more of measurements satisfy optimum criteria for biases among methods. All 10 laboratories met minimum imprecision requirements, but 25%-53% of the results reported by 4 of the 7 suboptimal laboratories failed to satisfy the minimum criteria for bias. CONCLUSION: Agreement among vitamin B(6) methods is good, but large differences in laboratory proficiency exist, pointing to the need for vitamin B(6) reference materials and external quality assurance programs.

Chromatography, High Pressure Liquid↗
PubMed2005

Determination of carcinogenic tobacco-specific nitrosamines in mainstream smoke from U.S.-brand and non-U.S.-brand cigarettes from 14 countries.

Tobacco-specific nitrosamines (TSNAs) comprise one of the major classes of carcinogenic compounds in mainstream cigarette smoke. As part of collaborative efforts between the World Health Organization and the U.S. Centers for Disease Control and Prevention (CDC) to reduce tobacco use and resulting disease, the CDC examined carcinogenic TSNA levels from cigarettes obtained from selected countries around the world. Using a modern, high-throughput liquid chromatography/mass spectrometry/mass spectrometry method under stringent quality control protocols, we determined the carcinogenic TSNA levels in mainstream smoke from a globally marketed brand, Marlboro, and from local top-selling cigarette brands from 14 countries. The levels of carcinogenic TSNAs in mainstream smoke collected using a 35-ml puff volume, 60-s puff interval, and 2-s puff duration correlated well (R=0.79, p<.0001) with previously reported levels in the corresponding tobacco filler. Marlboro cigarettes purchased in 10 countries had significantly higher carcinogenic TSNA levels in mainstream smoke than did local-brand cigarettes from the same country. In only one country, Brazil, were the carcinogenic TSNA levels in mainstream smoke from Marlboro cigarettes significantly lower than in the locally popular brand. However, carcinogenic TSNA levels in mainstream smoke from Brazilian Marlboro cigarettes were usually lower than those in mainstream smoke from the Marlboros purchased in the other 13 countries, suggesting a reason for the difference. The wide range of mainstream smoke carcinogenic TSNA levels measured in the present study (8.7-312 ng/cigarette) suggest that manufacturers can lower the carcinogenic TSNA levels and that, for similar filter ventilation, carcinogenic TSNA levels in the tobacco filler of a cigarette are a useful indicator of the corresponding levels in mainstream smoke.

Carcinogens↗
PubMed2005

Urinary tobacco-specific nitrosamines and 4-aminobiphenyl hemoglobin adducts measured in smokers of either regular or light cigarettes.

Cigarette brands may differ in their reported yields of "tar" as determined by the Federal Trade Commission smoking-machine method. Brands with relatively lower tar and nicotine yields often are described as light cigarettes. Smokers of light cigarettes generally maintain a nicotine intake comparable to that of smokers of regular cigarettes through compensatory smoking behaviors, but similar data have not been reported for carcinogen biomarkers. In the present study we measured serum cotinine concentrations (a marker of nicotine exposure), urinary levels of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL, a tobacco-specific nitrosamine [TSNA]), and hemoglobin adducts of 4-aminobiphenyl (4-ABP) in 150 smokers of either regular or light cigarettes. The TSNA and aromatic amines are known carcinogens in tobacco smoke. Multiple regression models were developed for each of the analytes and used to calculate adjusted geometric means. We found no significant differences in the levels of these biomarkers between customary users of light and regular cigarettes. Thus the concentrations of the carcinogen biomarkers NNAL and 4-ABP in the smokers who regularly smoked light cigarettes were essentially the same as those in the smokers who chose regular cigarettes.

Adult↗