Glenville Jones

Bio: Glenville Jones is an academic researcher from Queen's University. The author has contributed to research in topics: Vitamin D and neurology & Vitamin. The author has an hindex of 53, co-authored 194 publications receiving 15582 citations. Previous affiliations of Glenville Jones include Johns Hopkins University.

The 2011 Report on Dietary Reference Intakes for Calcium and Vitamin D from the Institute of Medicine: What Clinicians Need to Know

Abstract: This article summarizes the new 2011 report on dietary requirements for calcium and vitamin D from the Institute of Medicine (IOM). An IOM Committee charged with determining the population needs for these nutrients in North America conducted a comprehensive review of the evidence for both skeletal and extraskeletal outcomes. The Committee concluded that available scientific evidence supports a key role of calcium and vitamin D in skeletal health, consistent with a cause-and-effect relationship and providing a sound basis for determination of intake requirements. For extraskeletal outcomes, including cancer, cardiovascular disease, diabetes, and autoimmune disorders, the evidence was inconsistent, inconclusive as to causality, and insufficient to inform nutritional requirements. Randomized clinical trial evidence for extraskeletal outcomes was limited and generally uninformative. Based on bone health, Recommended Dietary Allowances (RDAs; covering requirements of ≥97.5% of the population) for calcium range...

Current Understanding of the Molecular Actions of Vitamin D

Abstract: The important reactions that occur to the vitamin D molecule and the important reactions involved in the expression of the final active form of vitamin D are reviewed in a critical manner. After an overview of the metabolism of vitamin D to its active form and to its metabolic degradation products, the molecular understanding of the 1alpha-hydroxylation reaction and the 24-hydroxylation reaction of the vitamin D hormone is presented. Furthermore, the role of vitamin D in maintenance of serum calcium is reviewed at the physiological level and at the molecular level whenever possible. Of particular importance is the regulation of the parathyroid gland by the vitamin D hormone. A third section describes the known molecular events involved in the action of 1alpha,25-dihydroxyvitamin D3 on its target cells. This includes reviewing what is now known concerning the overall mechanism of transcriptional regulation by vitamin D. It describes the vitamin D receptors that have been cloned and identified and describes the coactivators and retinoid X receptors required for the function of vitamin D in its genomic actions. The presence of receptor in previously uncharted target organs of vitamin D action has led to a study of the possible function of vitamin D in these organs. A good example of a new function described for 1alpha,25-dihydroxyvitamin D3 is that found in the parathyroid gland. This is also true for the role of vitamin D hormone in skin, the immune system, a possible role in the pancreas, i.e., in the islet cells, and a possible role in female reproduction. This review also raises the intriguing question of whether vitamin D plays an important role in embryonic development, since vitamin D deficiency does not prohibit development, nor does vitamin D receptor knockout. The final section reviews some interesting analogs of the vitamin D hormone and their possible uses. The review ends with possible ideas with regard to future directions of vitamin D drug design.

The 2011 Report on Dietary Reference Intakes for Calcium and Vitamin D From the Institute of Medicine: What Clinicians Need to Know

Abstract: This report summarizes the findings of the 2011 Institute of Medicine Committee on dietary intake requirements for calcium and vitamin D in North America, and provides updated data from the previous Institute of Medicine report of 1997. The Committee extensively reviewed existing published evidence on dietary and supplemental intake requirements for calcium and vitamin D with respect to both skeletal health and extraskeletal chronic disease outcomes. Calcium and vitamin D intake requirements were examined for several risk indictors of bone and skeletal health as well as extraskeletal outcomes (including cancer, cardiovascular disease, diabetes, and autoimmune disorders, infectious diseases, neuropsychological function, and disorders of pregnancy). Recommended Dietary Allowance (RDA) was defined as the level of intake of calcium or serum 25-hydroxyvitamin D that would meet the requirements of at least 97.5% of the population. The available scientific data supported an important role for calcium and vitamin D in bone and skeletal health outcomes that was consistent with a cause-and-effect relationship. However, data from randomized clinical trials for extraskeletal health outcomes were limited and inconclusive regarding a possible relationship with calcium and vitamin D intake requirements, and no evidence was found for dose-response or other established criteria for cause-and-effect. For bone health outcome, RDAs of calcium ranged from 700 to 1300 mg/d for life-stage groups at ≥1 year of age, and RDAs of vitamin D were 600 IU/d for ages 1 to 70 years and 800 IU/d for ages ≥71 (corresponding to a serum 25-hydroxyvitamin D level of at least 20 ng/mL [50 nmol/L]). There was an assumption of minimal or no sun exposure for estimation of RDA levels because of the wide variation in vitamin D synthesis from ultraviolet light and concern over risk of skin cancer. No consistent evidence was found that dietary or supplemental intake of vitamin D levels above the RDA provides additional benefit for bone health or extraskeletal outcomes; several investigators have found an U-shaped curve for several outcomes related to vitamin D intake, with increased risks at both low and high levels. The findings of this report suggest that prevalence of vitamin D deficiency in North America has been overestimated. The data show that almost all individuals in this population meet their RDA for vitamin D.

Vitamin D deficiency.

Abstract: admission. This proportion could already be greater in some parts of the country and may increase if referrals of cases of self-poisoning increase faster than the facilities for their assessment and management. The provision of social work and psychiatric expertise in casualty departments may be one means of preventing unnecessary medical admissions without risk to the patients. Dr Blake's and Dr Bramble's figures do not demonstrate, however, that any advantage would attach to medical teams taking over assessment from psychiatrists except that, by implication, assessments would be completed sooner by staff working on the ward full time. What the figures actually suggest is that if assessment of overdoses were left to house doctors there would be an increase in admissions to psychiatric units (by 19°U), outpatients (by 5O°'), and referrals to social services (by 140o). So for house doctors to assess overdoses would provide no economy for the psychiatric or social services. The study does not tell us what the consequences would have been for the six patients who the psychiatrists would have admitted but to whom the house doctors would have offered outpatient appointments. E J SALTER

Nuclear receptors and lipid physiology: opening the X-files.

Abstract: Cholesterol, fatty acids, fat-soluble vitamins, and other lipids present in our diets are not only nutritionally important but serve as precursors for ligands that bind to receptors in the nucleus. To become biologically active, these lipids must first be absorbed by the intestine and transformed by metabolic enzymes before they are delivered to their sites of action in the body. Ultimately, the lipids must be eliminated to maintain a normal physiological state. The need to coordinate this entire lipid-based metabolic signaling cascade raises important questions regarding the mechanisms that govern these pathways. Specifically, what is the nature of communication between these bioactive lipids and their receptors, binding proteins, transporters, and metabolizing enzymes that links them physiologically and speaks to a higher level of metabolic control? Some general principles that govern the actions of this class of bioactive lipids and their nuclear receptors are considered here, and the scheme that emerges reveals a complex molecular script at work.