Metabolomic Profiling of Long-Term Weight Change: Role of Oxidative Stress and Urate Levels in Weight Gain.

OBJECTIVE: To investigate the association between long-term weight change and blood metabolites. METHODS: Change in BMI over 8.6 ± 3.79 years was assessed in 3,176 females from the TwinsUK cohort (age range: 18.3-79.6, baseline BMI: 25.11 ± 4.35) measured for 280 metabolites at follow-up. Statistically significant metabolites (adjusting for covariates) were included in a multivariable least absolute shrinkage and selection operator (LASSO) model. Findings were replicated in the Cooperative Health Research in the Region of Augsburg (KORA) study (n = 1,760; age range: 25-70, baseline BMI: 27.72 ± 4.53). The study examined whether the metabolites identified could prospectively predict weight change in KORA and in the Prostate, Lung, Colorectal, and Ovarian Cancer (PLCO) study (n = 471; age range: 55-74, baseline BMI: 27.24 ± 5.37). RESULTS: Thirty metabolites were significantly associated with change in BMI per year in TwinsUK using Bonferroni correction. Four were independently associated with weight change in the multivariable LASSO model and replicated in KORA: namely, urate (meta-analysis ß [95% CI] = 0.05 [0.040 to 0.063]; P = 1.37 × 10-19 ), gamma-glutamyl valine (ß [95% CI] = 0.06 [0.046 to 0.070]; P = 1.23 × 10-20 ), butyrylcarnitine (ß [95% CI] = 0.04 [0.028 to 0.051]; P = 6.72 × 10-12 ), and 3-phenylpropionate (ß [95% CI] = -0.03 [-0.041 to -0.019]; P = 9.8 × 10-8 ), all involved in oxidative stress. Higher levels of urate at baseline were associated with weight gain in KORA and PLCO. CONCLUSIONS: Metabolites linked to higher oxidative stress are associated with increased long-term weight gain.

Physical activity and cancer-specific mortality in the NIH-AARP Diet and Health Study cohort.

Higher physical activity levels have been associated with a lower risk of developing various cancers and all-cancer mortality, but the impact of pre-diagnosis physical activity on cancer-specific death has not been fully characterized. In the prospective National Institutes of Health-AARP Diet and Health Study with 293,511 men and women, we studied prediagnosis moderate to vigorous intensity leisure time physical activity (MVPA) in the past 10 years and cancer-specific mortality. Over a median 12.1 years, we observed 15,001 cancer deaths. Using Cox proportional hazards regression, we estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for MVPA with cancer mortality overall and by 20 specific cancer sites, adjusting for relevant risk factors. Compared to participants reporting never/rare MVPA, those reporting >7 hr/week MVPA had a lower risk of total cancer mortality (HR = 0.89, 95% CI 0.84-0.94; p-trend <0.001). When analyzed by cancer site-specific deaths, comparing those reporting >7 hr/week of MVPA to those reporting never/rare MVPA, we observed a lower risk of death from colon (HR = 0.70; 95% CI 0.57-0.85; p-trend <0.001), liver (0.71; 0.52-0.98; p-trend = 0.012) and lung cancer (0.84; 0.77-0.92; p-trend <0.001) and a significant p-trend for non-Hodgkins lymphoma (0.80; 0.62-1.04; p-trend = 0.017). An unexpected increased mortality p-trend with increasing MVPA was observed for death from kidney cancer (1.42; 0.98-2.03; p-trend = 0.016). Our findings suggest that higher prediagnosis leisure time physical activity is associated with lower risk of overall cancer mortality and mortality from multiple cancer sites. Future studies should confirm observed associations and further explore timing of physical activity and underlying biological mechanisms.

Anthropometric measures and physical activity and the risk of lung cancer in never-smokers: a prospective cohort study.

Worldwide, lung cancer in never-smokers is ranked the seventh most common cause of cancer death; however, the etiology of lung cancer in never-smokers is unclear. We investigated associations for body mass index (BMI) at various ages, waist circumference, hip circumference, and physical activity with lung cancer in 158,415 never-smokers of the NIH-AARP Diet and Health Study. Multivariable hazard ratios (HR) and 95% confidence intervals (CI) were estimated from Cox proportional hazards models. Over 11 years of follow-up, 532 lung cancer cases occurred. The risk estimate for obese (BMI ≥ 30 kg/m(2)) participants at baseline was 1.21 (95%CI = 0.95-1.53) relative to those with a normal BMI between 18.5 ≤ BMI<25.0. Overweight (25.0 ≤ BMI<30.0) at age 18 (HR(overweight-vs-normal) = 1.51;95%CI = 1.01-2.26) and time spent sitting (HR(≥ 3 hrs-vs-<3 hrs) = 1.32;95%CI = 1.00-1.73) was each associated with lung cancer after adjustment for baseline BMI, as was waist (HR(Q4-vs-Q1) = 1.75;95%CI = 1.09-2.79) and hip circumference (HRQ4-vs-Q1 = 0.62;95%CI = 0.39-0.99), after mutual adjustment for each other and baseline BMI. No associations were observed for vigorous activity or television watching. In summary, using a large prospective cohort study, we found no evidence that BMI at baseline or middle age was associated with decreased lung cancer risk in never smokers. If anything, we observed some evidence for positive associations with a larger BMI or waist circumference.

RNA interference is an antiviral defence mechanism in Caenorhabditis elegans.

RNA interference (RNAi) is an evolutionarily conserved sequence-specific post-transcriptional gene silencing mechanism that is well defined genetically in Caenorhabditis elegans. RNAi has been postulated to function as an adaptive antiviral immune mechanism in the worm, but there is no experimental evidence for this. Part of the limitation is that there are no known natural viral pathogens of C. elegans. Here we describe an infection model in C. elegans using the mammalian pathogen vesicular stomatitis virus (VSV) to study the role of RNAi in antiviral immunity. VSV infection is potentiated in cells derived from RNAi-defective worm mutants (rde-1; rde-4), leading to the production of infectious progeny virus, and is inhibited in mutants with an enhanced RNAi response (rrf-3; eri-1). Because the RNAi response occurs in the absence of exogenously added VSV small interfering RNAs, these results show that RNAi is activated during VSV infection and that RNAi is a genuine antiviral immune defence mechanism in the worm.