RESUMEN
Bone has been considered a structure essential for mobility, calcium homeostasis, and hematopoietic function. Recent advances in bone biology have highlighted the importance of skeleton as an endocrine organ which regulates some metabolic pathways, in particular, insulin signaling and glucose tolerance. This review will point out the role of bone as an endocrine "gland" and, specifically, of bone-specific proteins, as the osteocalcin (Ocn), and proteins involved in bone remodeling, as osteoprotegerin, in the regulation of insulin function and glucose metabolism.
RESUMEN
Glucocorticoid induced osteoporosis (GIO) is the most frequent form of drug induced osteoporosis. Glucocorticoids affect osteoblastogenesis, osteoclastogenesis and promote the apoptosis of osteoblasts and osteocytes. A decrease of bone mineral density has been described in several pediatric diseases that require glucocorticoids, both as long-term replacement therapy, such as Congenital Adrenal Hyperplasia, and as treatment of acute phase or relapses, such as asthma, juvenile rheumatoid arthritis, inflammatory bowel diseases, systemic lupus erythematosus, organ transplantation and Steroid Sensitive Nephrotic Syndrome. The increasing number of children with GIO and at risk of fractures reflects the complex nature of this condition, and the need of development of anti-osteoporotic drugs. In this review, we focus on the mechanisms of GIO in some pediatric diseases and on treatment of osteoporosis. We also report data on new signaling pathways as potential targets for future anti-osteoporotic drugs.
RESUMEN
BACKGROUND: Increased carotid intima-media thickness (cIMT) is considered a marker of early-onset atherosclerosis and it seems to predict cardiovascular events both in obese and diabetic subjects. We aimed to evaluate early signs of atherosclerosis and investigate for predisposing factors in children and adolescents affected by type 1 diabetes (T1DM) or obesity, comparing them with healthy controls. METHODS: Out of 71 enrolled subjects (mean age 12.8 ± 2.3 years), 26 had T1DM and 24 were obese, while 21 age- and sex-matched subjects acted as controls. cIMT was measured using standardized methods. Serum glucose, insulin, cholesterol, triglycerides and C-reactive protein levels were evaluated. An oral glucose tolerance test (OGTT) was performed in obese subjects. RESULTS: Diabetic and obese individuals showed higher cIMT mean values than healthy controls (p < 0.005). cIMT of the three examined segments correlated positively with fasting glucose levels and negatively with units of insulin/kg/day administered in T1DM individuals. A positive correlation between insulin levels (basal and after oral glucose load) and cIMT of common, internal and external carotid artery was found in obese subjects (p < 0.03). High density cholesterol levels represented a protective factor for cIMT in this latter group of the study population. CONCLUSIONS: Our findings show that cIMT correlates with high insulin levels (a sign of insulin resistance) in obese patients and with high fasting glucose levels (a sign of relative insulin deficiency) in T1DM subjects, confirming the need of reducing hyperinsulinism and monitoring blood glucose levels in these subjects to prevent atherosclerosis.