An Asian viewpoint on the use of vitamin D and calcium in osteoporosis treatment: Physician and patient attitudes and beliefs

<p>Abstract</p> <p>Background</p> <p>Osteoporosis treatment guidelines recommend calcium and vitamin D supplementation for both prevention as well as treatment, however, compliance with these guidelines is often unsatisfactory. This study investigated the opinion of Asian physicians and Asian patients regarding vitamin D and calcium and patients' use of both.</p> <p>Methods</p> <p>Physicians selected from Malaysia, Taiwan, Philippines, Korea and Singapore were asked to grade the significance of vitamin D and calcium in the treatment of osteoporosis and their patients' use of these supplements. In addition, physicians recruited seven eligible osteoporotic women to answer a questionnaire to determine their use of vitamin D and calcium, and their attitudes and beliefs regarding these supplements.</p> <p>Results</p> <p>In total, 237 physicians and 1463 osteoporosis patients completed the questionnaire. The results revealed that 22% of physicians in Malaysia, 12% in Taiwan, 72% in the Philippines, 50% in Korea and 24% in Singapore rated the importance of vitamin D supplementation as being extremely important. For calcium, 27% of physicians in Malaysia, 30% in Taiwan, 80% in the Philippines, 50% in Korea and 38% in Singapore rated the importance as being extremely important. Forty-three percent of patients in Malaysia, 38% in Taiwan, 73% in the Philippines, 35% in Korea and 39% in Singapore rated the importance of vitamin D as being extremely important. For calcium, 69% of patients in Malaysia, 58% in Taiwan, 90% in the Philippines, 70% in Korea and 55% in Singapore rated the importance as being extremely important. In addition, results of the patient questionnaire revealed that only a very small number regularly took both supplements. In addition, the results indicated that, with the exception of patients from the Philippines, the majority of patients had no or infrequent discussion with their physician about vitamin D and calcium.</p> <p>Conclusions</p> <p>There is generally suboptimal appreciation by both physicians and patients of the importance of vitamin D and calcium for maintenance of bone health as reflected in the low number of patients who reported regularly taking these supplements. Recognition of this problem should translate to appropriate action to improve education for both physicians and patients, with a goal to increase use of these supplements among Asian patients with osteoporosis.</p

Differential Modulation of Beta-Adrenergic Receptor Signaling by Trace Amine-Associated Receptor 1 Agonists

Trace amine-associated receptors (TAAR) are rhodopsin-like G-protein-coupled receptors (GPCR). TAAR are involved in modulation of neuronal, cardiac and vascular functions and they are potentially linked with neurological disorders like schizophrenia and Parkinson's disease. Subtype TAAR1, the best characterized TAAR so far, is promiscuous for a wide set of ligands and is activated by trace amines tyramine (TYR), phenylethylamine (PEA), octopamine (OA), but also by thyronamines, dopamine, and psycho-active drugs. Unfortunately, effects of trace amines on signaling of the two homologous β-adrenergic receptors 1 (ADRB1) and 2 (ADRB2) have not been clarified yet in detail. We, therefore, tested TAAR1 agonists TYR, PEA and OA regarding their effects on ADRB1/2 signaling by co-stimulation studies. Surprisingly, trace amines TYR and PEA are partial allosteric antagonists at ADRB1/2, whereas OA is a partial orthosteric ADRB2-antagonist and ADRB1-agonist. To specify molecular reasons for TAAR1 ligand promiscuity and for observed differences in signaling effects on particular aminergic receptors we compared TAAR, tyramine (TAR) octopamine (OAR), ADRB1/2 and dopamine receptors at the structural level. We found especially for TAAR1 that the remarkable ligand promiscuity is likely based on high amino acid similarity in the ligand-binding region compared with further aminergic receptors. On the other hand few TAAR specific properties in the ligand-binding site might determine differences in ligand-induced effects compared to ADRB1/2. Taken together, this study points to molecular details of TAAR1-ligand promiscuity and identified specific trace amines as allosteric or orthosteric ligands of particular β-adrenergic receptor subtypes