Cholecalciferol, also known as vitamin D3 and colecalciferol, is a type of vitamin D that is made by the skin when exposed to sunlight; it is found in some foods and can be taken as a dietary supplement.
Calcitriol is the active form of vitamin D, normally made in the kidney. It is also known as 1,25-dihydroxycholecalciferol. It is a hormone which binds to and activates the vitamin D receptor in the nucleus of the cell, which then increases the expression of many genes. Calcitriol increases blood calcium (Ca2+) mainly by increasing the uptake of calcium from the intestines.
Calcifediol, also known as calcidiol, 25-hydroxycholecalciferol, or 25-hydroxyvitamin D3 (abbreviated 25(OH)D3), is a form of vitamin D produced in the liver by hydroxylation of vitamin D3 (cholecalciferol) by the enzyme vitamin D 25-hydroxylase. Calcifediol can be further hydroxylated by the enzyme 25(OH)D-1α-hydroxylase, primarily in the kidney, to form calcitriol (1,25-(OH)2D3), which is the active hormonal form of vitamin D.
Arnold Seymour Relman — known as Bud Relman to intimates — was an American internist and professor of medicine and social medicine. He was editor of The New England Journal of Medicine (NEJM) from 1977 to 1991, where he instituted two important policies: one asking the popular press not to report on articles before publication and another requiring authors to disclose conflicts of interest. He wrote extensively on medical publishing and reform of the U.S. health care system, advocating non-profit delivery of single-payer health care. Relman ended his career as professor emeritus at Harvard Medical School in Boston, Massachusetts.
Cytochrome P450 family 24 subfamily A member 1 (abbreviated CYP24A1) is a member of the cytochrome P450 superfamily of enzymes encoded by the CYP24A1 gene. It is a mitochondrial monooxygenase which catalyzes reactions including 24-hydroxylation of calcitriol (1,25-dihydroxyvitamin D3). It has also been identified as vitamin D3 24-hydroxylase.(EC 1.14.15.16)
CYP2R1 is cytochrome P450 2R1, an enzyme which is the principal vitamin D 25-hydroxylase. In humans it is encoded by the CYP2R1 gene located on chromosome 11p15.2. It is expressed in the endoplasmic reticulum in liver, where it performs the first step in the activation of vitamin D by catalyzing the formation of 25-hydroxyvitamin D.
Fibroblast growth factor 21 is a protein that in mammals is encoded by the FGF21 gene. The protein encoded by this gene is a member of the fibroblast growth factor (FGF) family and specifically a member of the endocrine subfamily which includes FGF23 and FGF15/19. FGF21 is the primary endogenous agonist of the FGF21 receptor, which is composed of the co-receptors FGF receptor 1 and β-Klotho.
Vitamin D5 (sitocalciferol) is a form of vitamin D.
Vitamin D deficiency or hypovitaminosis D is a vitamin D level that is below normal. It most commonly occurs in people when they have inadequate exposure to sunlight, particularly sunlight with adequate ultraviolet B rays (UVB). Vitamin D deficiency can also be caused by inadequate nutritional intake of vitamin D; disorders that limit vitamin D absorption; and disorders that impair the conversion of vitamin D to active metabolites, including certain liver, kidney, and hereditary disorders. Deficiency impairs bone mineralization, leading to bone-softening diseases, such as rickets in children. It can also worsen osteomalacia and osteoporosis in adults, increasing the risk of bone fractures. Muscle weakness is also a common symptom of vitamin D deficiency, further increasing the risk of fall and bone fractures in adults. Vitamin D deficiency is associated with the development of schizophrenia.
JeffreyFlier is an American physician, endocrinologist; widely cited scientist; the Higginson Professor of Medicine and Physiology at Harvard Medical School; and a Distinguished Service Professor at the same institution. He was the 21st Dean of the Faculty of Medicine at Harvard University from 2007 to 2016.
Michael F. Holick is an American adult endocrinologist, specializing in vitamin D, such as the identification of both calcidiol, the major circulating form of vitamin D, and calcitriol, the active form of vitamin D. His work has been the basis for diagnostic tests and therapies for vitamin D-related diseases. He is a professor of medicine at the Boston University Medical Center and editor-in-chief of the journal Clinical Laboratory.
Sir Stephen Patrick O'Rahilly is an Irish-British physician and scientist known for his research into the molecular pathogenesis of human obesity, insulin resistance and related metabolic and endocrine disorders.
Leonid Poretsky is a Russian-born American endocrinologist. His research interests include mechanisms of insulin action in the ovary, endocrinological aspects of AIDS, and clinical outcomes in diabetes. He has authored over 150 publications and has served on the National Institutes of Health's review committees and on the editorial boards of the Journal of Clinical Endocrinology and Metabolism and other endocrine journals.
Kurt Julius Isselbacher was a German-born American physician and held the position of Mallinckrodt Distinguished Professor of Medicine at Harvard Medical School and director emeritus of the Massachusetts General Hospital Cancer Center.
Gregg Leonard Semenza is a pediatrician and Professor of Genetic Medicine at the Johns Hopkins School of Medicine. He serves as the director of the vascular program at the Institute for Cell Engineering. He is a 2016 recipient of the Albert Lasker Award for Basic Medical Research. He is known for his discovery of HIF-1, which allows cancer cells to adapt to oxygen-poor environments. He shared the 2019 Nobel Prize in Physiology or Medicine for "discoveries of how cells sense and adapt to oxygen availability" with William Kaelin Jr. and Peter J. Ratcliffe. Semenza has had ten research papers retracted due to falsified data.
William G. Kaelin Jr. is an American Nobel laureate physician-scientist. He is a professor of medicine at Harvard University and the Dana–Farber Cancer Institute. His laboratory studies tumor suppressor proteins. In 2016, Kaelin received the Albert Lasker Award for Basic Medical Research and the AACR Princess Takamatsu Award. He also won the Nobel Prize in Physiology or Medicine in 2019 along with Peter J. Ratcliffe and Gregg L. Semenza.
Walter L. Miller is an American endocrinologist and professor emeritus of pediatrics at the University of California, San Francisco (UCSF). Miller is expert in the field of human steroid biosynthesis and disorders of steroid metabolism. Over the past 40 years Miller's group at UCSF has described molecular basis of several metabolic disorders including, congenital adrenal hyperplasia, pseudo vitamin D dependent rickets, severe, recessive form of Ehlers-Danlos syndrome, 17,20 lyase deficiency caused by CYP17A1 defects, P450scc deficiency caused by CYP11A1 defects, P450 oxidoreductase deficiency.
Daniel Kalman Podolsky is an American gastroenterologist and member of the National Academy of Medicine. He serves as President of the University of Texas Southwestern Medical Center. and co-chairman of Southwestern Health Resources, a collaboration between UT Southwestern and Texas Health Resources that cares for patients across North Texas and includes more than 30 hospitals, 300 clinics, and 2,600 physicians.
Steven Grinspoon is an American physician who is a Professor of Medicine at Harvard Medical School, Chief of the Massachusetts General Hospital (MGH) Metabolism Unit, and Director of the Nutrition Obesity Research Center at Harvard. In addition, he is the MGH Endowed Chair in Neuroendocrinology and Metabolism. His work investigates the neuroendocrine regulation of body composition, and physiologic consequences of fat distribution on cardiovascular disease and inflammation. He has investigated the effects of reduced growth hormone on metabolic dysregulation in obesity and was the first to propose the use of a Growth Hormone-releasing Hormone (GHRH) analogue to increase endogenous GH secretion on lipodystrophy and generalized obesity, which led to the FDA approval of Tesamorelin for excess visceral fat accumulation in HIV-infected patients. This work has now been extended to show effects on non-alcoholic fatty liver disease (NAFLD). More recently, his research focuses on the inflammatory mechanisms by which ectopic fat and other metabolic perturbations contribute to HIV-Cardiovascular disease (CVD), and in this regard, he led the AHA State of the Science Conference on CVD in HIV. Additionally, he is leading the multicenter REPRIEVE study, the first study of a primary prevention strategy for CVD in people living with HIV. He has also investigated increased Renin-Angiotensin-Aldosterone System (RAAS) activation and immune activation in relationship to visceral fat accumulation, and the mechanisms of subcutaneous adipose dysfunction involving DICER. Grinspoon has served on the Harvard faculty since 1995 and has been selected by the American Society for Clinical Investigation and the Association of American Physicians for his scientific contributions. He received the American Federation of Medical Research Investigator of the Year Award in 2005 and the Edward H. Ahrens Jr. Award for Patient Oriented Research in 2014 as well as the Endocrine Society Laureate Award for Translational Research in 2016. He has published over 330 articles and mentored over 40 trainees in his career. He was elected as a Member of the American Clinical and Climatological Association for his achievements in 2017. His work demonstrating the effects of Tesamorelin to reduce hepatic fat and fibrosis progression in NAFLD, published in Lancet HIV, was a finalist for the Clinical Research Forum’s top 10 Clinical Research Achievement Awards in 2020. In 2015, he became the Principal Investigator of the NIH-funded Nutrition Obesity Research Center at Harvard.
Eleftheria Maratos-Flier is an American endocrinologist, and emerita Professor of Medicine at Harvard Medical School, best known for her expertise in the pathophysiology and prevention of obesity-related metabolic disorders, and for her discoveries on the neuroendocrine control of feeding behaviour. She is a contributing author to known textbooks and reviews in internal medicine, endocrinology, and physiology. Her marriage with professor Jeffrey Flier, was noted by Forbes as a lasting and productive bond between eminent medical scholars. They have two adult daughters who are also physicians. She is also known as Terry Maratos-Flier.
