This is a Ph.D. dissertation. The aim of this thesis was to understand the role of 1,25(OH)2D3 and other steroid hormones in the regulation of active duodenal calcium absorption. To achieve this aim, the authors analyzed active duodenal calcium absorption at molecular and functional level. Contents include: Introduction: Calcium, The vitamin D endocrine system, Calcium (re)absorption, Active calcium absorption, vitamin D independent mechanisms; Aims and Scope of the study; Vitamin D dependent active duodenal calcium absorption; Active calcium absorption throughout the female reproductive cycle; The contribution of altered active absorption to the pathogenesis of glucocorticoid-induced bone loss; Discussion; Summary; Perspectives.

Calcium Entry Channels in Non-Excitable Cells focuses on methods of investigating the structure and function of non-voltage gated calcium channels. Each chapter presents important discoveries in calcium entry pathways, specifically dealing with the molecular identification of store-operated calcium channels which were reviewed by earlier volumes in the Methods in Signal Transduction series. Crystallographic and pharmacological approaches to the study of calcium channels of epithelial cells are also discussed. Calcium ion is a messenger in most cell types. Whereas voltage gated calcium channels have been studied extensively, the non-voltage gated calcium entry channel genes have only been identified relatively recently. The book will fill this important niche.

This volume represents the first attempt to present in one place the clinical syndromes and the pathophysiologic basis for the "resistance states" to each of the classes of steroid hormones. Glucocorticoids, mineralocorticoids, androgens, estrogens, progesterone and vitamin D have widely diverse roles ranging from the control of homeostasis to reproduction and bone formation. They are similar in that they share a chemical structure and that their action is in the cell nucleus where they induce transcription of specific genes leading to synthesis of function-specific proteins. Clinical syndromes of steroid hormone resistance to androgens (complete and partial testicular feminization), aldosterone (pseudo hypoaldosteronism) and vitamin D (vitamin D-dependent rickets type II) have been known for many years. Progesterone and glucocorticoid resistance syndromes have been described only recently. Resistance to estrogens has not been reported in man or in animals. It is hoped that a detailed reexamination of what is known about each of these conditions at the clinical and molecular levels will enhance our understanding of the function of these hormones and their mechanisms of action. New insight and research initiatives should result. G.P. Chrousos D.L. Loriaus M.B. Lipsett vii ACKNOWLEDGMENTS The contents of this volume are based in part on the proceedings of an International Conference held in Bethesda in the summer of 1984. This conference was sponsored by the National Institute of Child Health and Human Development, Bethesda, Maryland.

We present to our readers the proceedings of the Second International Workshop on Phosphate. A short account of the history of the effort led to the Phosphate Workshops is appro priate and can be of interest to the reader. The idea for Phosphate Workshops was born in the early days of November, 1974. One of us (S. G. M. ) suggested the thought to a group of scientists gathered for a luncheon in one of the attrac tive small restaurants in Weisbaden, Germany. The purpose of the workshop was to bring together interested scientists to discuss the newer developments and the recent advances in the field of phosphate metabolism and the other related minerals. An Organizing Committee made of Shaul G. Massry (USA), Louis V. Avioli (USA), Philippe Bordier (France), Herbert Fleisch (Switzerland), and Eduardo Slatopolsky (USA) was formed. The First Workshop was held in Paris during June 5-6, 1975 and was hosted by Dr. Philippe Bordier. Its proceeding was already published. The Second Workshop took place in Heidelberg during June 28-30, 1976 and was hosted by Dr. Eberhard Ritz. Both of these workshops were extremely successful scientific endeavors, and the need for them was demonstrated by the great interest they generated among the scientific community. The Or ganizing Committee, therefore, decided to continue with the tradi tion to hold additional Workshops annually or every other year.

Osteoporosis is one of the most clinically relevant disabling chronic disease encountered in clinical practice. A common cause of osteoporosis is glucocorticoid excess, as glucocorticoids may increase bone resorption, inhibit bone formation, have indirect actions on bone by decreasing intestinal calcium absorption and induce hypercalciuria. This book presents a comprehensive overview of the effects of glucocorticoids on bone metabolism and structure and on the diagnosis and treatment of glucocorticoid-induced osteoporosis. It aims at providing updated information on the pathogenesis, diagnosis and treatment of this often dramatic complication of glucocorticoid excess. Being one of the few publications completely devoted to glucocorticoid-induced osteoporosis it will heighten the awareness of specialists who prescribe glucocorticoids of the clinical relevance of this treatment complication. 'Glucocorticoid-Induced Osteoporosis' is addressed to clinical experts as well as to general practitioners who will both benefit from the comprehensive and integrative view of the management of patients exposed to glucocorticoids.

Hypercalcemia is the most common life-threatening metabolic disorder associated with cancer. The pathophysiological, epidemiological and clinical aspects of hypercalcemia of malignancy are presented in this issue, with a focus on the recently discovered humoral factor responsible for the development of hypercalcemia. With a better understanding of the pathophysiology of this condition and the development of new potent drugs, capable of inhibiting bone resorption, especially bisphosphonates, the clinician will be more successful in correcting hypercalcemia in the great majority of patients.

Vitamin D deficiency is prevalent today not only among the elderly but pervasively throughout all ages of life.This is due, in part, to systemic diseases that affect vitamin D metabolism, to changes in lifestyle, such as insufficient exposure to sunlight, and to increased use of sunscreen. Apart from the obvious effects of vitamin D deficiency on skeletal metabolism, the problem is assuming even greater significance because observational and interventional studies have linked vitamin D deficiency to cardiovascular disease, cancer, and diabetes. This book addresses a variety of important issues that have emerged from this fast-moving area of clinical medicine. The topics include assays of vitamin D and its binding protein, effects on aging and associated complications, primary and secondary states of altered parathyroid hormone secretion, vitamin D in the growing years of children and adolescents, nutritional requirements, and vitamin D as it relates to systemic disorders such as diabetes mellitus. Vitamin D in Clinical Medicine aims to offer new insights, in an evidence-based way, on important issues related to vitamin D. It is written for general practitioners and internists, as well as for endocrinologists, nutritionists, pulmonologists, cardiologists, and oncologists.