The Association Between Serum Riboflavin and Flavin Mononucleotide With Pancreatic Cancer: Findings From a Prospective Cohort Study.

OBJECTIVES: Vitamin B2 (riboflavin) has a prime role in metabolic reactions imperative to cell cycle and proliferation. We investigated the associations between serum concentrations of riboflavin flavin mononucleotide with the risk of pancreatic cancer in a nested case-control study involving 58 cases and 104 matched controls. METHODS: The Singapore Chinese Health Study, an ongoing prospective cohort study of 63,257 Chinese Singaporeans. Conditional logistic regression method was used to evaluate these associations with adjustment for potential confounders including the level of education, body mass index, smoking status, alcohol consumption, history of diabetes, serum cotinine and pyridoxal 5'-phosphate, estimated glomerular filtration rate, and total methyl donors (ie, the sum of serum choline, betaine, and methionine). RESULTS: The risk of pancreatic cancer increased with increasing level of serum riboflavin in a dose-dependent manner, especially in men (Ptrend = 0.003). The odds ratio (95% confidence intervals) of pancreatic cancer for the second and third tertiles of serum riboflavin, compared with the lowest tertile, were 9.92 (1.65-59.77) and 25.59 (3.09-212.00), respectively. This positive association was stronger in individuals with a longer follow-up period (≥7 years). CONCLUSIONS: The findings suggest a potential role of riboflavin in the development of pancreatic cancer, especially in men.

Circulating markers of cellular immune activation in prediagnostic blood sample and lung cancer risk in the Lung Cancer Cohort Consortium (LC3).

Cell-mediated immune suppression may play an important role in lung carcinogenesis. We investigated the associations for circulating levels of tryptophan, kynurenine, kynurenine:tryptophan ratio (KTR), quinolinic acid (QA) and neopterin as markers of immune regulation and inflammation with lung cancer risk in 5,364 smoking-matched case-control pairs from 20 prospective cohorts included in the international Lung Cancer Cohort Consortium. All biomarkers were quantified by mass spectrometry-based methods in serum/plasma samples collected on average 6 years before lung cancer diagnosis. Odds ratios (ORs) and 95% confidence intervals (CIs) for lung cancer associated with individual biomarkers were calculated using conditional logistic regression with adjustment for circulating cotinine. Compared to the lowest quintile, the highest quintiles of kynurenine, KTR, QA and neopterin were associated with a 20-30% higher risk, and tryptophan with a 15% lower risk of lung cancer (all ptrend < 0.05). The strongest associations were seen for current smokers, where the adjusted ORs (95% CIs) of lung cancer for the highest quintile of KTR, QA and neopterin were 1.42 (1.15-1.75), 1.42 (1.14-1.76) and 1.45 (1.13-1.86), respectively. A stronger association was also seen for KTR and QA with risk of lung squamous cell carcinoma followed by adenocarcinoma, and for lung cancer diagnosed within the first 2 years after blood draw. This study demonstrated that components of the tryptophan-kynurenine pathway with immunomodulatory effects are associated with risk of lung cancer overall, especially for current smokers. Further research is needed to evaluate the role of these biomarkers in lung carcinogenesis and progression.

Mid-pregnancy cotinine and risks of orofacial clefts and neural tube defects.

OBJECTIVE: Past studies of cigarette smoking as a contributor to orofacial clefts and neural tube defects (NTDs) used self-reports of smoke exposures. We have correlated measurements of cotinine (a nicotine metabolite) in mid-pregnancy sera with clefts and NTDs. STUDY DESIGN: From a repository of >180 000 mid-pregnancy serum specimens collected in California from 2003 to 2005 and linked to delivery outcome information, we identified 89 orofacial cleft-associated pregnancies, 80 NTD-affected pregnancies, and randomly selected 409 pregnancy specimens that corresponded to infants without malformations as control subjects. Cotinine was measured by liquid chromatography-mass spectrometry. No smoke exposure was defined as cotinine values <2 ng/mL, and any exposure was defined as >or=2 ng/mL. RESULTS: We observed odds ratios of 2.1 (95% CI, 1.0-4.4) for clefts and 0.4 (95% CI, 0.1-1.7) for NTDs associated with exposure. After adjusting for race/ethnicity, age, and serum folate levels, odds ratios were 2.4 (95% CI, 1.1-5.3) and 0.6 (95% CI, 0.1-2.5). We explored 2 cotinine levels, 2 to 10 ng/mL and >10 ng/mL for clefts (data were too sparse for NTDs). Odds ratios for these levels were 3.3 (95% CI, 0.9-11.9) and 1.7 (95% CI, 0.7-4.2), respectively. CONCLUSION: Smoking exposures, as measured with cotinine levels during mid-pregnancy, were associated with increased risks of clefts and possibly reduced risks of NTDs.

Plasma choline and betaine and their relation to plasma homocysteine in normal pregnancy.

BACKGROUND: Plasma concentrations of total homocysteine (tHcy) decrease during pregnancy. This reduction has been investigated in relation to folate status, but no study has addressed the possible role of betaine and its precursor choline. OBJECTIVE: We investigated the courses of plasma choline and betaine during normal human pregnancy and their relations to plasma tHcy. DESIGN: Blood samples were obtained monthly; the initial samples were taken at gestational week (GW) 9, and the last samples were taken approximately 3 mo postpartum. The study population comprised 50 women of West African descent. Most of the subjects took folic acid irregularly. RESULTS: Plasma choline (geometric x; 95% reference interval) increased continuously during pregnancy, from 6.6 (4.5, 9.7) micromol/L at GW 9 to 10.8 (7.4, 15.6) micromol/L at GW 36. Plasma betaine decreased in the first half of pregnancy, from 16.3 (8.6, 30.8) micromol/L at GW 9 to 10.3 (6.6, 16.2) micromol/L at GW 20 and remained constant thereafter. We confirmed a reduction in plasma tHcy, and the lowest concentration was found in the second trimester. From GW 16 onward, an inverse relation between plasma tHcy and betaine was observed. Multiple regression analysis showed that plasma betaine was a strong predictor of plasma tHcy from GW 20 onward. CONCLUSIONS: The steady increase in choline throughout gestation may ensure choline availability for placental transfer with subsequent use by the growing fetus. Betaine becomes a strong predictor of tHcy during the course of pregnancy. Both of these findings emphasize the importance of choline and betaine status during normal human pregnancy.

Birth prevalence of homocystinuria.

Serious complications of homocystinuria caused by cystathionine beta-synthase deficiency can be prevented by early intervention. We determined the prevalence of 6 specific mutations in 1133 newborn blood samples. Our results suggest that homocystinuria is more common than previously reported. Newborn screening for homocystinuria through mutation detection should be further considered.