David Segev

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNovel cyclization of diallenic sulfonesSamuel Braverman and David SegevCite this: J. Am. Chem. Soc. 1974, 96, 4, 1245–1247Publication Date (Print):February 1, 1974Publication History Published online1 May 2002Published inissue 1 February 1974https://pubs.acs.org/doi/10.1021/ja00811a060https://doi.org/10.1021/ja00811a060research-articleACS PublicationsRequest reuse permissionsArticle Views270Altmetric-Citations107LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

24(R),25-Dihydroxyergocalciferol [24,25-(OH)2–D2] is 1.7 times less potent than 24(R), 25-(OH)2D3, 25-Hydroxyvitamin D2 (25OHD2), or 25OHD3 in the displacement of (3H)25OHD3 from rat serum binding proteins. 1,25-(OH)2D2 is 1.3 times less potent than 1,25-(OH)2D3 in the displacement of (3H)1,25-(OH)2D3 from a chick intestinal binding receptor. In light of binding affinity and chromatographic differences between vitamin D3 and its D2 analogs, it is our view that methods which purport to measure 1,25-(OH)2D and 24,25-(OH)2D probably underestimate the contributions of D2 metabolites. This is particularly important in the case of plasma extracts from patients given large doses of vitamin D2. (J ClinEndocrinol Metab50: 773, 1980)

CONTEXT: The contemporary literature on the relationship between serum TSH levels and osteoporotic fractures in euthyroid individuals is limited by conflicting results and analyses conducted on a small number of fractures. OBJECTIVE: Our objective was to examine the association between the normal range of variation of TSH and the incidence of hip fractures in male and female euthyroid patients aged 65 years or older. DESIGN AND SETTING: We performed a population-based historical prospective cohort study within the Clalit Health Services population. PARTICIPANTS: Clalit Health Services members aged ≥65 years with at least 1 TSH measurement during the year 2004. We excluded patients with preexisting hip fracture, thyroid disease, malignancy, or chronic kidney disease. OUTCOME MEASURES: The primary outcome was hip fracture, and the secondary outcome was any other osteoporotic fracture. STATISTICAL ANALYSIS: Adjusted odds ratios comparing episodes of each outcome across 3 TSH groups (low, 0.35-1.6 mIU/L; intermediate, 1.7-2.9 mIU/L; high, 3-4.2 mIU/L) were generated using logistic regression models. RESULTS: The 14 325 included participants suffered from 514 hip fractures (mean follow-up, 102 ± 3 months). Women, but not men, in the lowest TSH group had a higher incidence of hip fractures (odds ratio = 1.28, 95% confidence interval = 1.03-1.59, P = .029) when compared with the intermediate group, after multivariate adjustment for age, comorbidities, and use of drugs affecting bone metabolism. There was no difference in hip fracture incidence between intermediate- and high-TSH groups. No association was found between TSH levels and other osteoporotic fractures. CONCLUSIONS: TSH levels within the lower normal range are associated with an increased risk of hip fractures in euthyroid women, but not men, aged 65 years and more.