622 research outputs found
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 (10â11 - 10â6 M) and thyroxin (10â6 M) for 1â24 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 10â7M 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
Fragility of bone material controlled by internal interfaces
Bone material is built in a complex multiscale arrangement of mineralized collagen fibrils containing water, proteoglycans and some noncollagenous proteins. This organization is not static as bone is constantly remodeled and thus able to repair damaged tissue and adapt to the loading situation. In preventing fractures, the most important mechanical property is toughness, which is the ability to absorb impact energy without reaching complete failure. There is no simple explanation for the origin of the toughness of bone material, and this property depends in a complex way on the internal architecture of the material on all scales from nanometers to millimeters. Hence, fragility may have different mechanical origins, depending on which toughening mechanism is not working properly. This article reviews the toughening mechanisms described for bone material and attempts to put them in a clinical context, with the hope that future analysis of bone fragility may be guided by this collection of possible mechanistic origins
Progressive acetabular dysplasia in a boy with mucopolysaccharoidosis type IV A (Morquio syndrome): a case report
Occipito-Vertebral Dissociation in Connection with Extensive Cervical Spine Malsegmentation in a Boy with MĂśbius Syndrome
Synophyrs, curly eyelashes and Ptyrigium colli in a girl with Desbuquois dysplasia: a case report and review of the literature
Distinctive Tomographic Abnormalities of the Craniocervical Region in a Patient with Osteogensis Imperfecta Type IV B
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
Significant traumatic atrophy of the spinal cord in connection with severe cervical vertebral body hypoplasia in a boy with Larsen syndrome: a case report and review of the literature
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
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