Location: Obesity and Metabolism Research Unit
2009 Annual Report
OBJECTIVE 1: Determine the effects of specific foods, fortified foods, and nutrients on bone health of at-risk population groups. Sub-objective 1.A. Determine the effects of carbonated beverages and milk on calcium kinetics and calcium efflux from the skeleton of women and girls (Van Loan, Allen, and Huang). Sub-objective 1.B. Determine the effects of vitamin B12 deficiency on markers of calcium kinetics, bone health, and calcium metabolism in postmenopausal women (Allen, Van Loan).
OBJECTIVE 2: Investigate vitamin B12 and zinc intestinal absorption and metabolism in at-risk populations. Sub-objective 2.A. Determine the absorption of 14C-vitamin B12 from fortified foods in elderly with gastric atrophy and H. pylori infection, pre- and post H. pylori treatment (Allen, Huang). Sub-objective 2.B. Determine the impact of SNPs in a major Zn uptake gene (ZIP4) on dietary Zn absorption using ZIP4-expressing cell lines. (Huang, Allen).
OBJECTIVE 3. Investigate the effect of Zn supplementation on the development of prostate cancer, a cancer common in African-Americans, using a mouse prostate cancer model (TRAMP) (Huang).
The B-12 and osteoporosis project is underway. Human subjects and radiation protection have been completed and approve. Three women have passed the screening process, were dosed with 41Ca isotope and have started urine collection. One woman has completed the entire protocol. Because so many subjects with osteopenia were taking medications and were therefore ineligible for study, we have obtained approval to drop osteopenia as an eligibility criterion; vitamin B12 deficiency is still required.
The B-12 absorption in women with gastric atrophy has started. Human subjects and radiation protective procedures have been completed as well as all study protocols for specimen collection and laboratory work. Protocol for inclusion of isotope into baked bread has been finalized. One subject without gastric atrophy has been enrolled, dosed, and specimens collected; 5 other women are in the screening process to determine eligibility.
To determine the benefits of vitamin B12 supplements or vitamin B12 fortified milk for neurological and cognitive function of elderly in Chile. Enrollment of the subjects has been completed. Samples collected at baseline and after 3 and 9 months of supplementation have been analyzed for vitamin B12, and analysis of holotranscobalamin is in progress.
Eggs labeled in vivo with 14C-vitamin B12 were obtained by feeding the labeled vitamin to hens. The eggs were scrambled and doses containing approximately 2 ug of the vitamin were fed to 10 human subjects. Plasma samples were collected hourly for the first 12 hours then every 24 h for 9 days. Urine and feces were collected throughout. Analysis of plasma 14C shows that the vitamin was absorbed, with a peak around 10 hours after consumption. Large amounts of radioactivity appeared in urine during the first 48 hours. Analysis of 14C in the fecal samples is in progress and required to quantify the bioavailability of the vitamin. The project will be completed in FY 2010.
The mammalian and yeast expression clones containing human ZIP4 cDNA sequence with different SNPs were established. Plasmids were transfected and transformed into human kidney epithelial cells (HK293) and change Zrt1/change Zrt2 yeast cells. The expression of introduced ZIP4 was confirmed by RT-PCR (gene expression) and western blot analysis (protein expression). The zinc uptake function of ZIP4 in transfected/transformed cells was determined by 65Zn uptake assay. Our results indicated that SNPs between Africans and Europeans in ZIP4 did not change the rate of zinc uptake of this protein. Investigation of zinc supplementation and prostate cancer using a TRAMP mouse model animal protocol has been developed, submitted and approved by the Institutional Animal Care and Use Committee of the University of California Davis. 2 breeding pairs of TRAMP mice were established.