Thyroid hormones increase insulin-like growth factor mRNA levels in the clonal osteoblastic cell line MC3T3-E1

AbstractThyroid hormones are known to affect skeletal growth and maturation by influencing both bone resorption and bone formation. Their exact mechanism of action, however, is still unknown. Local factors such as prostaglandins, TGF-β or IGF-I were suggested to mediate their effects. Thyroid hormones were reported to stimulate expression of IGF-I mRNA in liver and kidney and to increase IGF-I release from bone organ cultures and osteoblast-like cells. Therefore we studied the effect of thyroid hormones on IGF-I mRNA expression in MC3T3-E1 cells. The cells were grown in culture for 5 to 7 days and treated with triiodothyronine (10−11 - 10−6 M) and thyroxin (10−6 M) for 1–24 h. Cellular mRNA was isolated and subjected to Northern hybridization. The amount of IGF-I mRNA, which is already expressed in this cell line under control conditions, was markedly enhanced by T3 and T4. This effect was found to be dose-dependent with a maximum at 10−7M and could already be seen after 3 h increasing up to 24 h. Our findings indicate that IGF-I expression in osteoblasts is directly regulated by thyroid hormones. We conclude that IGF-I expression belongs to the phenotypic characteristics of mature osteoblasts, and that thyroid hormones play an important role in differentiation of MC3T3-E1 cells along the osteoblastic lineage

Tomographic assessment of the spine in children with spondylocostal dysotosis syndrome

OBJECTIVE: The aim of this study was to perform a detailed tomographic analysis of the skull base, craniocervical junction, and the entire spine in seven patients with spondylocostal dysostosis syndrome. METHOD: Detailed scanning images have been organized in accordance with the most prominent clinical pathology. The reasons behind plagiocephaly, torticollis, short immobile neck, scoliosis and rigid back have been detected. Radiographic documentation was insufficient modality. RESULTS: Detailed computed tomography scans provided excellent delineation of the osseous abnormality pattern in our patients. CONCLUSION: This article throws light on the most serious osseous manifestations of spondylocostal dysostosissyndrome

Mid-diaphyseal Endosteal Thickening With Subsequent Medullary Narrowing in a Patient With Hallermann-Streiff Syndrome

We report on a 5-year-old girl who presented with the full clinical criteria of Hallermann-Streiff syndrome (HSS). Classically, overtubulation (thin and gracile) bones are the characteristic and constant features in HSS. Interestingly, our present patient manifested unusual mid-diaphyseal endosteal thickening with subsequent medullary narrowing (defective endosteal resorption). To the best of our knowledge no previous reports described such unusual feature in a patient with HSS