STABLE ISOTOPES IN OBESITY RESEARCH

Obesity is recognized as a major public health problem. Obesity is a multifactorial disease and is often associated with a wide range of comorbidities including hypertension, non-insulin dependent (Type II) diabetes mellitus, and cardiovascular disease, all of which contribute to morbidity and mortality. This review deals with stable isotope mass spectrometric methods and the application of stable isotopes to metabolic studies of obesity. Body composition and total energy expenditure (TEE) can be measured by mass spectrometry using stable isotope labeled water, and the metabolism of protein, lipid, and carbohydrate can be measured using appropriate labeled tracer molecules

Dietary reference values for vitamin K

Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) derives dietary reference values (DRVs) for vitamin K. In this Opinion, the Panel considers vitamin K to comprise both phylloquinone and menaquinones. The Panel considers that none of the biomarkers of vitamin K intake or status is suitable by itself to derive DRVs for vitamin K. Several health outcomes possibly associated with vitamin K intake were also considered but data could not be used to establish DRVs. The Panel considers that average requirements and population reference intakes for vitamin K cannot be derived for adults, infants and children, and therefore sets adequate intakes (AIs). The Panel considers that available evidence on occurrence, absorption, function and content in the body or organs of menaquinones is insufficient, and, therefore, sets AIs for phylloquinone only. Having assessed additional evidence available since 1993 in particular related to biomarkers, intake data and the factorial approach, which all are associated with considerable uncertainties, the Panel maintains the reference value proposed by the Scientific Committee for Food (SCF) in 1993. An AI of 1 mu g phylloquinone/kg body weight per day is set for all age and sex population groups. Considering the respective reference body weights, AIs for phylloquinone are set at 70 mu g/day for all adults including pregnant and lactating women, at 10 mu g/day for infants aged 7-11 months, and between 12 mu g/day for children aged 1-3 years and 65 mu g/day for children aged 15-17 years. (C) 2017 European Food Safety Authority. EFSA Journal published by John Wiley and Sons Ltd on behalf of European Food Safety Authority

A Method to Assess Genomic DNA MethylationUsing High-Performance Liquid Chromatography/Electrospray Ionization Mass Spectrometry

In corso di registrazione un brevetto Internazionale (documentazione depositata secondo le leggi statunitensi ed internazionali attualmente vigenti) per l\u2019invenzione di un metodo per la misurazione dei liveli di metilazione genomica del DNA. (Application number: 60/400,756, depositato 8/2/2002)

Aging alters global hepatic DNA hydroxymethylation in mice, as determined by a novel LC/MS-MS method

Aging is associated with changes in global DNA methylation (mC), but changes in DNA hydroxymethylation (hmC) are not established due to a relative lack of methods available to measure hmC. Both modifications can affect gene expression and may be important in aging. We have developed a method to measure 5'-methyl-2'-deoxycytidine and 5'-hydroxymethyl-2'-deoxycytidine in DNA using liquid chromatography/tandem mass spectrometry (LC/MS-MS) and used this method to assess global hmC and mC levels in hepatic tissue from young (9 months; n=10) and old (23 months; n=6) C57BL/6 male mice. DNA was enzymatically hydrolyzed and isotopomers [15N3]-2'-deoxycytidine and (methyl-d3, ring-6-d1)-5-methyl-2'-deoxycytidine were added as internal standards. The mixture of DNA hydrolysates and internal standards were separated through LC, and nucleosides of interest were detected by MS-MS in positive ion mode using multiple reaction monitoring. Global mC and hmC levels were calculated as a percentage of total deoxycytidine residues in genomic DNA. Liver tissue from old mice had significantly higher global hmC relative to young mice (0.32\ub10.02% vs 0.24\ub10.01%; p=0.02), while mC levels did not change. Using this new method we have found that aging is associated with an increase in global DNA hmC, a finding that may be useful in understanding the physiological mechanisms behind aging