Estimation of Background Serum 2,3,7,8-TCDD Concentrations By Using Quantile Regression in the UMDES and NHANES Populations

Chen, Qixuan; Garabrant, David H.; Hedgeman, Elizabeth; Little, Roderick J. A.; Elliott, Michael R.; Gillespie, Brenda W.; Hong, Bor‐Cherng; Lee, Shih Yuan; Lepkowski, James M.; Franzblau, Alfred; Adriaens, Peter; Demond, Avery H.; Patterson, Donald G.

doi:10.1097/ede.0b013e3181ce9550

Cited by 21 publications

(18 citation statements)

References 14 publications

(12 reference statements)

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“…This analysis predicted changes in a given quantile, e.g. the 90th quantile of outcome variables instead of their mean, allowing a more comprehensive view of the relationship between predictors and outcomes [50, 51]. Wald test was used to test equality of coefficients across quantiles [52].…”

Section: Methodsmentioning

confidence: 99%

Investigating the associations between adiposity, life course overweight trajectories, and telomere length

Wulaningsih

Watkins²,

Matsuguchi

et al. 2016

Aging

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Obesity may accelerate ageing through chronic inflammation. To further examine this association, we assessed current adiposity, adiposity at early adulthood and life course overweight trajectories in relation to leukocyte telomere length (LTL). We included a total of 7,008 nationally representative U.S. residents and collected information on objectively measured body mass index (BMI), waist circumference and percent body fat. BMI at age 25 and overweight trajectories were assessed using self-reported history. Leukocyte telomere length (LTL) relative to a standard DNA reference (T/S ratio) was quantified by polymerase chain reaction (PCR). Linear regression models were used to examine the difference in LTL across adiposity measures at examination, BMI at age 25, and overweight trajectories. A 0.2% decrease in telomere length (95% CI:−0.3 to −0.07%) was observed for every kg/m2 increase in BMI, whereas a unit increase in waist circumference (cm) and percent body fat contributed to a 0.09% and 0.01% decrease in LTL, respectively. Higher BMI and being obese at age 25 contributed to lower LTL at older ages. Associations between weight loss through life course and LTL were observed, which further marked the importance of life course adiposity dynamics as a determinant of ageing.

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Section: Methodsmentioning

confidence: 99%

Investigating the associations between adiposity, life course overweight trajectories, and telomere length

Wulaningsih

Watkins²,

Matsuguchi

et al. 2016

Aging

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“…PBDEs levels in biotic tissues from polluted regions are obviously higher than those from the general environment, and consequently we summarized the data from these environments separately. The percentile method is a useful method for estimating background concentrations of chemical pollutants in biotic and environmental samples (Chen et al, 2010;Isosaari et al, 2006). The 90th percentile level as well as the 95th percentile level is used to estimate the upper extremes of pollutant concentrations.…”

Section: Literature Data On Environmental Exposure Levels Of Biotic Tmentioning

confidence: 99%

Determination of environmentally relevant exposure concentrations of polybrominated diphenyl ethers for in vitro toxicological studies

Wei

Zhao

Liu

et al. 2010

Toxicology in Vitro

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a b s t r a c tToxicological studies at environmentally relevant concentrations are essential for understanding ecotoxic and health risks of pollutants such as polybrominated diphenyl ethers (PBDEs). However, no information is available on what exposure levels of PBDEs in vitro studies are environmentally relevant. We exposed MCF-7, HepG2, H295R and PC12 cells to BDE-47, and measured BDE-47 concentrations in the cells after exposure. We also used the percentile method to summarize literature data on environmental exposure levels of biotic tissues to PBDEs. The exposure concentration that resulted in a BDE-47 burden in cells close to the 90th percentile of PBDEs levels in tissues was assigned as the upper limit for the environmentally relevant concentration. Exposure to 1 nM BDE-47 resulted in PBDEs burdens in MCF-7, HepG2 and H295R cells close to the 90th percentile but PBDEs burdens in PC12 cells were higher than the 90th percentile. In consideration of the high exposure levels in PBDE-polluted areas, we concluded that the highest environmentally relevant exposure concentration of PBDEs in culture media should be approximately 10 nM for MCF-7, HepG2 and H295R cells, and <10 nM for PC12 cells. These results provide an approximate reference for setting environmentally relevant exposure concentrations of PBDEs for studies in vitro.

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“…An online appendix provides additional details, including citations to general approaches that might be useful to other readers of this article (Koenker, 2005; Koenker and Hallock, 2001). Implementing software has been described by Chen and colleagues (Chen et al, 2010). All analyses were performed in SAS 9.3 (SAS Institute, Cary NC).…”

Section: Methodsmentioning

confidence: 99%

Cannabis smoking and serum C-reactive protein: A quantile regressions approach based on NHANES 2005–2010

Alshaarawy

Anthony

2015

Drug and Alcohol Dependence

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Background Pre-clinical studies link cannabinoid-1 receptor activation to inflammation and atherosclerotic effects; anti-inflammation and immunosuppression seem to be mediated by cannabinoid-2 receptor activation. In this epidemiological study, we aim to present estimates on suspected cannabis-attributable immunomodulation as manifest in serum C-reactive protein (CRP) levels as non-specific inflammatory markers with interpretable clinical values. With strength of data from recent large nationally representative community sample surveys, the research approach illustrates value of a quantile regressions approach in lieu of the commonly used but relatively arbitrary cutpoints for CRP values. Methods The study population encompasses 20–59 year old participants from the National Health and Nutrition Examination Surveys, 2005–2010 (n = 1115 recently active cannabis smokers and 8041 non-smokers, identified via confidential Audio Computer Assisted Self-Interviews). Age, sex, race, education, income-poverty ratio, alcohol consumption, and tobacco smoking also were measured, together with body mass index (BMI), which actually might be on a mediational path. Quantile regressions, with bootstrapping for variance estimation, made it possible to hold these covariates constant while estimating cannabis-CRP associations. Results Evidence suggesting possible cannabis-attributable immunomodulation emerges at CRP levels below the median (p<0.05). Whereas BMI might help explain a cannabis link with serum CRP, but BMI-stratified analyses disclosed no appreciable variation of the cannabis-CRP relationship across BMI subgroups. Conclusions Extending pre-clinical research on cannabis-attributable immunomodulation, this study’s CRP evidence points toward possible anti-inflammatory effects of cannabis smoking. More definitive evidence can be derived by combining pre-clinical research, studies of patients, and epidemiological research approaches.

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Estimation of Background Serum 2,3,7,8-TCDD Concentrations By Using Quantile Regression in the UMDES and NHANES Populations

Cited by 21 publications

References 14 publications

Investigating the associations between adiposity, life course overweight trajectories, and telomere length

Investigating the associations between adiposity, life course overweight trajectories, and telomere length

Determination of environmentally relevant exposure concentrations of polybrominated diphenyl ethers for in vitro toxicological studies

Cannabis smoking and serum C-reactive protein: A quantile regressions approach based on NHANES 2005–2010

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