The branching ratio of enzymatically synthesized α-glucans impacts microbiome and metabolic outcomes of in vitro fecal fermentation.

The aim of this study was to evaluate the impacts of enzymatically synthesized α-glucans possessing α-1,4- and α-1,6-glucose linkages, and varying in branching ratio, on colonic microbiota composition and metabolic function. Four different α-glucans varying in branching ratio were synthesized by amylosucrase from Neisseria polysaccharea and glycogen branching enzyme from Rhodothermus obamensis. The branching ratios were found to range from 0 % to 2.8 % using GC/MS. In vitro fecal fermentation analyses (n = 8) revealed that the branching ratio dictates the short-chain fatty acid (SCFA) generation by fecal microbiota. Specifically, slightly branched (0.49 %) α-glucan resulted in generation of significantly (P < 0.05) higher amounts of propionate, compared to more-branched counterparts. In addition, the amount of butyrate generated from this α-glucan was statistically (P > 0.05) indistinguishable than those observed in resistant starches. 16S rRNA sequencing revealed that enzymatically synthesized α-glucans stimulated Lachnospiraceae and Ruminococcus related OTUs. Overall, the results demonstrated metabolic function of colonic microbiota can be manipulated by altering the branching ratio of enzymatically synthesized α-glucans, providing insights into specific structure-function relationships between dietary fibers and the colonic microbiome. Furthermore, the slightly branched α-glucans could be used as functional carbohydrates to stimulate the beneficial microbiota and SCFAs in the colon.

Macromolecular α-glucans with α-1,3/α-1,4 branching structures produced using dual glycosyltransferases: Elucidation of physicochemical and slowly digestible properties.

Amylosucrase from Neisseria polysaccharea (NpAS) produces the linear amylose-like α-glucans by the elongation property from sucrose, and 4,3-α-glucanotransferase from Lactobacillus fermentum NCC 2970 (4,3-αGT) newly synthesizes the α-1,3 linkages after cleaving the α-1,4 linkages by the glycosyltransferring property. This study focused on the synthesis of high molecular α-1,3/α-1,4-linked glucans by combining NpAS and 4,3-αGT and analyzed their structural and digestive properties. The enzymatically synthesized α-glucans have a molecular weight of >1.6 × 107 g mol-1, and the α-4,3 branching ratios on the structures increased as the amount of 4,3-αGT increased. The synthesized α-glucans were hydrolyzed to linear maltooligosaccharides and α-4,3 branched α-limit dextrins (α-LDx) by human pancreatic α-amylase, and the amounts of produced α-LDx were increased depending on the ratio of synthesized α-1,3 linkages. In addition, approximately 80 % of the synthesized products were partially hydrolyzed by mammalian α-glucosidases, and the glucose generation rates decelerated as the amounts of α-1,3 linkages increased. In conclusion, new types of α-glucans with α-1,4 and α-1,3 linkages were successfully synthesized by a dual enzyme reaction. These can be utilized as slowly digestible and prebiotic ingredients in the gastrointestinal tract due to their novel linkage patterns and high molecular weights.

Levels of tobacco-specific metabolites among non-smoking lung cancer cases at diagnosis: case-control findings.

BACKGROUND: Environmental tobacco smoking (ETS) significantly contributes to morbidity and mortality and is a known risk factor for lung cancer development in lifelong nonsmokers. The metabolite 4-(methylnitrosamino)- 1-(3-pyridyl)-1-butanol (NNAL) and its glucuronides (NNAL-Glucs) have now emerged as leading biomarkers for the study of carcinogen exposure in non-smokers exposed to ETS. MATERIALS AND METHODS: We carried out our study on NNAL in the urine of non-smokers exposed to ETS and the association between ETS and lung cancer. Subjects were enrolled from 2008-2010. NNAL was analyzed for 74 non-smoking lung cancer and 85 healthy controls. The main objective of this study was to provide an estimate of the risk of lung cancer from exposure to ETS in the Korean population. RESULTS: The mean NNAL concentration in urine was significantly lower in non-smoking patient groups (n=74) than in control groups (n=85) (4.7±15.0 pg/mg, 6.5 ± 17.9 pg/mg, respectively, Mann-Whitney U test, p<0.001). CONCLUSIONS: The urine NNAL of non-smoking patients with lung cancer was not elevated with regard to the non-smoking control group. This may be due to life-style changes after diagnosis. A prospective study will be needed to evaluate the association of NNAL and non-smoking lung cancer.

Preschool children and their mothers are more exposed to paternal smoking at home than school children and their mothers.

BACKGROUND: Exposure to secondhand smoke (SHS) is a major risk to human health, and the home is the greatest single source of SHS in children. Here, the authors assessed SHS exposure of children and mothers by paternal smoking at home, and investigated how different this exposure is according to smoking location and children's age. METHODS: Two hundred-five families were enrolled in this study as trios of fathers, mothers, and children. Nicotine concentrations in hair were measured using liquid chromatography-tandem mass spectrometry to determine long-term exposure to SHS. RESULTS: Differences between the smoker group and nonsmoker group in nicotine levels were statistically significant in both children and their mothers. However, difference between the indoor-smoker group and outdoor-smoker group was marginally significant in children and was not significant in their mothers. In the indoor-smoker group, preschool children and their mothers had nicotine concentrations about twice as high as school children and their mothers, respectively. In the outdoor-smoker group, however, differences between two age groups in nicotine levels were significant in preschool children, but not their mothers. CONCLUSION: These findings indicate that paternal smoking at home leads to significant exposure to SHS in their children and spouses, which is not completely prevented by smoking outside. Especially, preschool children and their mothers appear to be most at risk for SHS exposure among nonsmoking household members.

Neonatal hair nicotine levels and fetal exposure to paternal smoking at home.

Exposure to environmental tobacco smoke (ETS) is a major risk to human health, and the home is the greatest single source of ETS for children. The authors investigated fetal exposure to paternal smoking at home during pregnancy. Korean families were included as trios of fathers, mothers, and neonates identified in 2005-2007. Sixty-three trios were finally enrolled in this study after exclusion of those in which the mother was a smoker or was regularly exposed to ETS at places other than the home. Nicotine and cotinine concentrations in hair were measured by using liquid chromatography-tandem mass spectrometry to determine long-term exposure to ETS. The difference between neonatal nicotine concentrations in the smoker and nonsmoker groups was not statistically significant. However, in the indoor-smoker group, neonatal nicotine concentrations were significantly higher than in the outdoor and nonsmoker groups (P < 0.05). Furthermore, neonatal nicotine concentrations in the outdoor-smoker group were not different from those in the nonsmoker group. These findings indicate that paternal smoking inside the home leads to significant fetal and maternal exposure to ETS and may subsequently affect fetal health. Conversely, findings show that paternal smoking outside the home prevents the mother and her fetus from being exposed to ETS.