Authors:C. Baskett, V. Spate, M. Mason, C. Reams, and J. Morris
The selenium excreted in urine can be measured to assess the dietary status of selenium, an essential trace element in human nutrition. The objectives of this work were: 1) to develop a procedure, capable of high sample throughout, by which the major interferences can be reduced such that selenium concentrations can be measured in urine by Neutron Activation Analysis (NAA) using77mSe (17.4 s; and 2) to apply the method to a human dietary selenium study in which several selenium monitors were compared. The method involves a pre-irradiation arsenic-coprecipitation separation of the selenium from urine in the presence of a high specific-activity75Se tracer. The processed urine samples are analyzed using NAA. The procedure was applied to 58 urine specimens longitudinally collected from 12 subjects consuming three different levels of selenium. A dose-response relationship was observed in urine as well as a high correlations with both serum and whole blood selenium concentrations.
Authors:V. Spate, M. Mason, C. Reams, C. Baskett, J. Morris, and D. Mills
In this study we report on the comparison between the total selenium in serum (total Se) with that which is apparently bound to high molecular weight (>12,000 D) species, presumably proteins (bound Se). Nine hundred seventy seven (977) serum samples arising out of a population-based epidemiological study were prepared in duplicate for the determination of total Se by pipeting directly into irradiation vials; and separate duplicate aliquots were dialyzed against DI water for the determination of bound Se. All samples were analyzed by neutron activation analysis via77mSe (17.4 s). A small dialyzable Se component (6%) (free Se), defined as the difference between the total Se minus the bound Se, was identified.
Authors:V. Spate, J. Morris, C. Baskett, M. Mason, C. Reams, D. Hunter, and W. Willett
The role of fluorine in human health has become somewhat controversial. It is widely accepted as protective against dental caries, may be protective against osteoporosis, and has been very conservatively implicated with osteosarcoma in male rats. In this study, we repot on the development of a neutron activation analysis method and its application to the analysis of human nails. We have found that toenails collected in population-based epidemiology studies apparently reflect fluoride intake.
Authors:C. Baskett, V. Spate, J. Morris, H. Anderson, M. Mason, C. Reams, T. Cheng, K. Zinn, G. Hill, and R. Dowdy
The principal objective of this study was to determine if the use of a stable enriched tracer of Se-76 could be used to determine the delay time between a dietary intake of selenium and its appearance in fingernails and toenails. Selenium is an essential trace element in human nutrition. It has been studied at the Missouri University Research Reactor (MURR) for the past 15 years using an Instrumental Neutron Activation Analysis (INAA) technique. The principal route of human exposure to selenium is through the diet. Selenium concentrations of nails, blood, hair, and urine have been used as indicators of dietary selenium intake. In this study, a cohort consisting of seven men and five women ingested three selenium supplements of 150 g each over a three day period. The selenium was enriched in Se-76 (96.48%) and ingested as selenite in orange juice following an overnight fast. Fingernails and toenails were collected prior to the selenium supplementation and for several months afterward to be used as biochemical indicators. The peak76Se concentration in the fingernails and toenails occurred at 19–23 and 16–32 weeks after supplementation, respectively.
Authors:M. Mason, V. Spate, J. Morris, C. Baskett, T. Cheng, C. Reams, L. Le Marchand, B. Henderson, and L. Kolonel
There is currently great interest in iodine as a micro nutrient. Both high and low intakes have been associated with thyroid cancer incidence. Development of dietary iodine monitors is needed to supplement the use of dietary recall methods which have not been well validated for iodine. In this study, 30 pooled urine samples, from ethnic groups on various islands in the South Pacific, were analyzed for iodine using epithermal instrumental neutron activation analysis (EINAA).
Authors:V. Spate, J. Morris, S. Chickos, C. Baskett, M. Mason, T. Cheng, C. Reams, C. West, C. Furnee, W. Willett, and P. Horn-Ross
An epithermal instrumental neutron activation analysis (EINAA) method, using a boron nitride irradiation capsule compatible with use in the University of Missouri Research Reactor pneumatic-tube irradiation facility, has been developed for the analysis of iodine in human nails. The principal objective was to determine if the nail could be used as a means of monitoring dietary intake of iodine. The EINAA method was used to analyze nails from subjects having iodine intakes that could be qualitatively differentiated. Iodine concentrations in nails from these subjects were positively correlated with apparent iodine intake.