L. Vanhaelst

Two years of replacement therapy in adults with growth hormone deficiency

Although several studies have shown beneficial short‐term effects of recombinant human growth hormone (rhGH) therapy in adult GH deficient (GHD) patients, few data are available on large groups of patients treated for more than one year. In addition, the optimal dose of rhGH for each patient and the baseline parameters that predict which patients will benefit most from therapy or will have adverse events are not entirely elucidated.

Development of Monoaminergic Neurotransmitters in Fetal and Postnatal Rat Brain: Analysis by HPLC with Electrochemical Detection

Abstract: The monoamines dopamine, norepinephrine, epinephrine, and serotonin and their major metabolites 3,4‐dihydroxyphenylacetic acid, homovanillic acid, 3‐methoxy‐4‐hydroxyphenylethylene glycol, and 5‐hydroxyindoleacetic acid were measured in the CNS of the rat during development from fetal day 18 to young adult. The catecholamines, serotonin, and their major metabolites remained low during fetal life. Concentrations measured in total brain started to increase around birth till the end of the fourth week of life after which steady‐state levels were measured. Our results suggest that although monoamine systems are already morphologically well developed during late gestational life, they probably become a significant functional system only around birth and early postnatal life.

Recommendations for the registration of new chemical entities used in the prevention and treatment of osteoporosis

Osteoporotic fractures are now widely recognized as a major health problem in elderly populations, causing significant morbidity and mortality and imposing a considerable financial burden on the health services [1]. Recent advances in the clinical management of osteoporosis, in particular the development of accurate and precise techniques to measure bone mass and the identification of agents that prevent or reverse bone loss, have resulted in increased therapeutic intervention in this disease. However, requirements for registration of an agent for prevention or treatment of osteoporosis are not uniform, leading to wide geographical variations in prescribing patterns. Within Europe, for example, several drugs are licensed for these indications in certain countries, but not in others. The need to standardize registration requirements of drugs for osteoporosis prompted the development of a European Working Group, composed of clinicians working in the field of bone disease and representatives of drug regulation authorities. The aim of this group was to generate guidelines for the development of new agents for prevention and treatment of osteoporosis, particularly postmenopausal osteoporosis. This paper reports recommendations for the preclinical and clinical studies that are considered by the group to be necessary prerequisites for drug registration in the future. The recommendations are based on currently available knowledge and technology and should be relevant to all European countries.

Do estrogens effectively prevent osteoporosis-related fractures?

Since Albright, [1] some 60 years ago, reported the benefi-cial effects of estrogens for decreasing urinary calcium ex-cretion and suggested that these harmones might be usefulin preventing postmenopausal osteoporosis, estrogen re-placement therapy (ERT) has been consistently regarded asthe first choice for prevention of trabecular and corticalbone loss in postmenopausal women [2–5]. However, seri-ous controversies remain over the cost/effectiveness oftreating every woman at the time of menopause [6], theoptimal timing for starting ERT [5], the minimal effectivedose of ERT acting on bone [7], and the duration of ERTneeded to prevent osteoporotic fractures [8]. The effective-ness of ERT for preventing osteoporosis-related fractures isundisputed and requirements for marketing authorizationfor ERT products have lightened compared with currentrequests for other therapeutic medications developed in thisfield [9, 10]. However, although the skeletal benefits ofERT for preventing trabecular or cortical bone loss canhardly be challenged, one might be wary of published evi-dence that prolonged ERT use unequivocally reduces therisk of hip fracture. Controlled clinical trials and systematicreviews were located using Medline 1970–1999 andEMBASE 1980–1999. Since 1985 we have searched scien-tific journals on bone and bibliographies of review articles.All prospective controlled trials were included for evalua-tion of the effects of hormone replacement therapy (HRT)on bone loss. A total of 57 prospective controlled trials wereidentified, 46 of which were randomized clinical trials(RCTs) and 15 were double blinded. All clinical trials as-sessing the effects of HRT on fracture rates were consid-ered. Two RCTs and one systematic review were identified[11].In the 46 randomized controlled trials comparing estro-gen (with or without progestins) (HRT) with placebo orcalcium on bone loss prevention, the study population var-ied from 14 to 875 women and the duration was from .5 to10 years. In general, they drew similar conclusions, i.e, thatestrogen intervention reduces the rate of postmenopausalbone loss at trabecular and cortical sites. An early double-blind trial [12] reported the preventive effects of HRT oncortical (metacarpal) bone loss for up to 10 years. Morerecent double-blind, placebo-controlled, randomized clini-cal trials confirmed these findings for oral [13], percutane-ous [14, 15], or transdermal [16] estrogens at the spine [13,14, 16], the forearm [16], and/or the hip [13, 16] for up to3 years. Two prospective open studies [17, 18] showedsimilar results for estrogen implants after 1 year. Whenstandardized for technique used for bone mineral density(BMD) assessment, the magnitude of the point estimatedifferences between the HRT and the control group variedgreatly from one study to another, depending upon the doseof HRT used (dose-related effect on bone mass in most

Recommendations for the registration of agents used in the prevention and treatment of glucocorticoid-induced osteoporosis

Glucocorticoid-induced osteoporosis is an important clinical problem, but there is little consensus about its management and in many countries no drug is licensed specifically for its prevention or treatment. In contrast, a number of agents are licensed for postmenopausal osteoporosis; however, extrapolation of data obtained in preclinical and clinical studies of postmenopausal osteoporosis to glucocorticoid-induced osteoporosis is problematic because of fundamental differences in the pathogenesis and pathophysiology of the two conditions. Prompted by the lack of standardization for registration requirements of agents for osteoporosis, and consequent wide geographical variations in prescribing patterns, we reported recommendations for the registration of new chemical entities in the prevention and treatment of postmenopausal osteoporosis [1]. Because of the particular problems associated with the evaluation of agents for glucocorticoidinduced osteoporosis, it was felt that specific recommendations for the registration of agents for use in the prevention and treatment of this condition were appropriate. This article reports the recommendations of our group for preclinical and clinical studies for registration of drugs for the prevention and treatment of glucocorticoid-induced osteoporosis. As in the case of our previously reported recommedations [1], these are based on currently available knowledge and technology and should be relevant to all European countries.

Cyclical Cushing's Disease: A Case Report

A 41-year-old man with clinical Cushings syndrome and intermittent central ACTH hypersecretion for a period of 9 1/2 years follow-up is described. Episodes of biochemical and clinical remission alternated with periods of florid Cushings disease, characterized by circadian hyperpulsatile ACTH and cortisol secretion. Responses to metyrapone and inhibition of ACTH and cortisol hypersecretion after high dose dexamethasone during active phases of the disease favored a central origin of ACTH hypersecretion, confirmed by simultaneous bilateral venous sampling of the sinus petrosus inferior. Prolonged clinical remission followed near total anterior hypophysectomy. However, on anatomopathological examination of the pituitary neither corticotroph cell hyperplasia nor a microadenoma could be documented. The possibility of a functional ACTH hypersecretion is discussed.

Recommendations for the Registration of Drugs Intended for Use in the Treatment of Male Osteoporosis

1Universitair Ziekenhuis Gent, Ghent, Belgium 2University of Cambridge Clinical School, Cambridge, United Kingdom 3Centre Hospitalier Universitaire d’Angers, Anger, France 4Hôpital Henri Mondor, Creteil, France 5Hôpital Universitaire St. Luc, Brussels, Belgium 6Staatliches Rheumakrankenhaus, Baden-Baden, Germany 7Vrije Universiteit Brussel, Brussels, Belgium 8WHO Collaborating Center for Public Health Aspects of Osteoarticular Disorders, University of Lie `ge, B lgium

Citrate infusion test in the diagnosis of hypocalcemia due to a mutation in the calcium-sensing receptor gene.

The calcium-sensing receptor (Ca-R) is a G-protein-coupled surface receptor that plays a crucial role in calcium homeostasis via parathyroid hormone secretion. Mutations of this receptor can cause a gain in, or loss of, function, leading to hypo- or hypercalcemia, respectively. We report here a family with hypocalcemia in whom a heterozygous missense mutation in exon 4 was demonstrated, predicting a proline to leucine substitution (P221L) in the extracellular part of the Ca-R. Clinical symptoms were limited to fatigue. When serum calcium was further lowered via a citrate infusion, a significant increase in circulating iPTH was observed, although with lower peak values than in normal controls, suggesting a gain in function of the Ca-R. Treatment with calcium supplements and calcitriol led to prohibitive hypercalciuria without normalizing serum calcium. The aims of this case report are: (1) to present a mutation in the Ca-R with a gain in function at a codon where previously loss of function was described, and (2) to suggest that measuring circulating iPTH during a citrate infusion in the presence of familial hypocalcemia is an additional test to diagnose this particular form of hypoparathyroidism.

Routing, processing and export of rat pituitary prolactin : Identification of A 36 kDa disulphide-bridged oligomeric preprolactin

To gain an insight in the routing, processing and export of rat prolactin, rat pituitary cells were cultured in serum-free medium in the presence of cycloheximide, carbonyl cyanide m-chlorophenylhydrazone, Brefeldin A and monensin. The potential influence of these perturbants, whose well documented effects are the altering of protein synthesis and transport, was studied on rat prolactin molecular size isoforms appearing in cellular extracts and in culture medium. The outcome of the culture experiments as recorded in vertical SDS-PAGE, thiol gradient electrophoresis and sequential SDS-PAGE followed by prolactin specific immunoblotting and densitometry, was as follows: (1) at the cellular level we were able to characterize a novel 36 kDa protein as a disulphide-bridged oligomeric precursor prolactin, which is presumably rapidly transformed in the cis/medial Golgi; to designate monomeric rat prolactin as an early Golgi protein and t o advance evidence that the main processing of the glycosylated rat prolactin is a cis/medial Golgi event; (2) in release none of the perturbants disturbed the relative distribution of monomeric and glycosylated rat prolactin, the main molecular size isoforms currently secreted by untreated pituitary cells, or induced the appearance of transformed molecular size isoforms; (3) the secretion mode indicates that rat prolactin is released via the regulated pathway in the presence of the perturbants used.