Biomarkers of folate status in NHANES: a roundtable summary123456

A roundtable to discuss the measurement of folate status biomarkers in NHANES took place in July 2010. NHANES has measured serum folate since 1974 and red blood cell (RBC) folate since 1978 with the use of several different measurement procedures. Data on serum 5-methyltetrahydrofolate (5MTHF) and folic acid (FA) concentrations in persons aged ≥60 y are available in NHANES 1999–2002. The roundtable reviewed data that showed that folate concentrations from the Bio-Rad Quantaphase II procedure (Bio-Rad Laboratories, Hercules, CA; used in NHANES 1991–1994 and NHANES 1999–2006) were, on average, 29% lower for serum and 45% lower for RBC than were those from the microbiological assay (MA), which was used in NHANES 2007–2010. Roundtable experts agreed that these differences required a data adjustment for time-trend analyses. The roundtable reviewed the possible use of an isotope-dilution liquid chromatography–tandem mass spectrometry (LC-MS/MS) measurement procedure for future NHANES and agreed that the close agreement between the MA and LC-MS/MS results for serum folate supported conversion to the LC-MS/MS procedure. However, for RBC folate, the MA gave 25% higher concentrations than did the LC-MS/MS procedure. The roundtable agreed that the use of the LC-MS/MS procedure to measure RBC folate is premature at this time. The roundtable reviewed the reference materials available or under development at the National Institute of Standards and Technology and recognized the challenges related to, and the scientific need for, these materials. They noted the need for a commutability study for the available reference materials for serum 5MTHF and FA

Biomarkers of vitamin B-12 status in NHANES: a roundtable summary123456

A roundtable to discuss the measurement of vitamin B-12 (cobalamin) status biomarkers in NHANES took place in July 2010. NHANES stopped measuring vitamin B-12–related biomarkers after 2006. The roundtable reviewed 3 biomarkers of vitamin B-12 status used in past NHANES—serum vitamin B-12, methylmalonic acid (MMA), and total homocysteine (tHcy)—and discussed the potential utility of measuring holotranscobalamin (holoTC) for future NHANES. The roundtable focused on public health considerations and the quality of the measurement procedures and reference methods and materials that past NHANES used or that are available for future NHANES. Roundtable members supported reinstating vitamin B-12 status measures in NHANES. They noted evolving concerns and uncertainties regarding whether subclinical (mild, asymptomatic) vitamin B-12 deficiency is a public health concern. They identified the need for evidence from clinical trials to address causal relations between subclinical vitamin B-12 deficiency and adverse health outcomes as well as appropriate cutoffs for interpreting vitamin B-12–related biomarkers. They agreed that problems with sensitivity and specificity of individual biomarkers underscore the need for including at least one biomarker of circulating vitamin B-12 (serum vitamin B-12 or holoTC) and one functional biomarker (MMA or tHcy) in NHANES. The inclusion of both serum vitamin B-12 and plasma MMA, which have been associated with cognitive dysfunction and anemia in NHANES and in other population-based studies, was preferable to provide continuity with past NHANES. Reliable measurement procedures are available, and National Institute of Standards and Technology reference materials are available or in development for serum vitamin B-12 and MMA

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Ratio of Double Beta-Decay Rates of \u3csup\u3e128,130\u3c/sup\u3eTe

We have measured the amounts of radiogenic 128Xe and 130Xe in two, old telluride minerals-krennerite (AuTe2) from Western Australia and altaite (PbTe) from Quebec. We calculated values of (4.2±0.8) × 10-4 and (4.4±0.8) × 10-4 for the ratio of the total ββ-decay half-lives, 130T1 2/128T1 2, from the amounts of radiogenic 130Xe and 128Xe in the krennerite and the altaite, respectively. These values are in good agreement with the ratio of half-lives calculated by the quasi-particle random phase approximation for 2v ββ-decay

Double Beta-Decay of Tellurium-128 and Tellurium-130

The isotopic composition of xenon has been determined in the gas released by stepwise heating of two, geologically-old tellurium minerals - melonite, NiTe2, from the Robb-Montbray property in Quebec and altaite, PbTe, from the Mattagami Lake area of Quebec. We calculate values of 2540 ± 680 and 2550 ± 1300 for the ratio of the ββ-decay half-lives, T1 2 128/T1 2 130, from the amounts of radiogenic 128Xe and 130Xe in the melonite and the altaite, respectively, and a value of T1 2 128 = (1.8 ± 0.7) × 1024y. Lepton number violation is not required by these results

Double Beta Decay of Tellurium-130

The isotopic composition of xenon is reported in four, neutron-irradiated tellurium minerals - tellurobismuthite from Boliden, Sweden, native tellurium from the Good Hope Mine of Gunnison County, Colorado, altaite from the Kirkland Lake area, Ontario, and altaite from the Mattagami Lake area, Quebec. From the amount of radiogenic 130Xe and pile-produced 131Xe in these samples, it is concluded that the half-life of 130Te for ββ-decay is ≲ 1 × 1021 y based on measured values of (1.0 ± 0.3) × 1021 y and higher. Our results demonstrate that there has been no significant partial leakage of radiogenic 130Xe from these minerals over geologic time. Larger values of T1 2 as indicated from some of the analysis reported here and in other studies, are attributed to recrystallization of the soft telluride minerals and complete resetting of the TeXe system after mineralization. The value obtained here for the half-life of 130Te is substantiated by recent measurements on xenon in tellurides from Kalgoorlie, Western Australia

Double Beta-Decay of ⁸²Se and ¹³⁰Te

The isotopic compositions of xenon and krypton in the mineral kitkaite, NiTeSe, were measured to determine the amounts of radiogenic 82Kr and 130Xe produced by the double-beta decay of 82Se and 130Te, respectively. From the ratio of radiogenic 82Kr to radiogenic 130Xe in this mineral, it is concluded that the half-life of 130Te is larger than that of 82Se by a factor of 7.3 ± 0.9. If the age of the host rock, 2.00 × 109 y, is taken as an upper limit on the gas-retention age of the mineral, then values of (1.25 ± 0.08) × 1021y and (1.72 ± 0.19) × 1020y are obtained as upper limits on the half-lives of 130Te and 82Se respectively. A more realistic upper limit of T82 1 2 ≤ (1.4 ± 0.2) × 1020y is obtained from these results and those of a recent measurement here indicating T8130 1 2 ≤ 1 × 1021y