Regulation of Human Bone Marrow Stromal Cell Proliferation and Differentiation Capacity by Glucocorticoid Receptor and AP-1 Crosstalk

Although marrow adipocytes and osteoblasts derive from a common bone marrow stromal cells (BMSCs), the mechanisms that underlie osteoporosis-associated bone loss and marrow adipogenesis during prolonged steroid treatment are unclear. We show in human BMSCs (hBMSCs) that glucocorticoid receptor (GR) signaling in response to high concentrations of glucocorticoid (GC) supports adipogenesis but inhibits osteogenesis by reducing c-Jun expression and hBMSC proliferation. Conversely, significantly lower concentrations of GC, which permit hBMSC proliferation, are necessary for normal bone mineralization. In contrast, platelet-derived growth factor (PDGF) signaling increases both JNK/c-Jun activity and hBMSC expansion, favoring osteogenic differentiation instead of adipogenesis. Indeed, PDGF antagonizes the proadipogenic qualities of GC/GR signaling. Thus our results reveal a novel c-Jun-centered regulatory network of signaling pathways in differentiating hBMSCs that controls the proliferation-dependent balance between osteogenesis and adipogenesis

Differential effects of exercise on tibial shaft marrow density in young female athletes

Context:Increased mechanical loading can promote the preferential differentiation of bone marrow mesenchymal stem cells to osteoblastogenesis, but it is not known whether long-term bone strength-enhancing exercise in humans can reduce marrow adiposity.Objective:Our objective was to examine whether bone marrow density (MaD), as an estimate of marrow adiposity 1) differs between young female athletes with contrasting loading histories and bone strengths and 2) is an independent predictor of bone strength at the weight-bearing tibia.Design:Mid-tibial MaD, cortical area (CoA), total area, medullary area, strength strain index (SSI), and cortical volumetric bone mineral density (vBMD) (total, endocortical, midcortical, and pericortical) was assessed using peripheral quantitative computed tomography in 179 female athletes involved in both impact and nonimpact loading sports and 41 controls aged 17&ndash;40 years.Results:As we have previously reported CoA, total area, and SSI were 16% to 24% greater in the impact group compared with the controls (all P &lt; .001) and 12% to 18% greater than in the nonimpact group (all P &lt; .001). The impact group also had 0.5% higher MaD than the nonimpact and control groups (both P &lt; .05). Regression analysis further showed that midtibial MaD was significantly associated with SSI, CoA, endocortical vBMD, and pericortical vBMD (P &lt; .05) in all women combined, after adjusting for age, bone length, loading groups, medullary area, muscle cross-sectional area, and percent fat.Conclusion:In young female athletes, tibial bone MaD was associated with loading history and was an independent predictor of tibial bone strength. These findings suggest that an exercise-induced increase in bone strength may be mediated via reduced bone marrow adiposity and consequently increased osteoblastogenesis.<br /

Disability Policies in France: Changes and Tensions between the Category-based, Universalist and Personalized Approaches

In this article, the authors show that the current French disability policy is traversed by conflicts between three different approaches to disability which came about at different periods in history. They begin by looking at the origins of disability policy in France. This policy was developed during the 20th century, from notions of repair, indemnification and compensation through rehabilitation. It became institutionalized in 1975, when two laws were passed, giving it the form of a category-based policy. Between 1970 and 2000, affected by the international situation, this policy came into conflict with a universalist policy. More recently there has been a desire to develop a personalized approach. Finally, the authors use two examples (taken from recent debates on the implementation in France of the new law of 11 February 2005) to show the tensions that have led to the coexistence of these three approaches within current disability policy

True heterotopic bone in the paralyzed patient

In past years the clinical and radiologic presentation of true heterotopic bone in the paralyzed patient has been confused with osteomyelitis, neoplasm, trauma, and thrombophlebitis. We reviewed 376 paralyzed patients' roentgenographic files and found 78 patients with soft tissue ossification unassociated with infection, neoplasm, or underlying fractures, which we called true heterotopic bone. From this population the usual spectrum of radiologic findings is described, so that the radiologist may separate roentgenographically a group of patients from other types of ectopic ossification.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46816/1/256_2004_Article_BF00347167.pd

Seasonal acclimatization to temperature in cardueline finches

1. Seasonal variation in body constituents and utilization of lipid, protein, and carbohydrate during cold stress in American goldfinches were studied to determine relations of these functions to the pronounced seasonal shift in thermogenic capacity documented in a previous study (Dawson and Carey, 1976).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47119/1/360_2004_Article_BF00686746.pd

Espérance de vie en santé : apport conceptuel et pratique de la Classification internationale des déficiences, incapacités, handicaps (CIDIH)

Le calcul de l'espérance de vie en santé s'appuie sur les mesures de la mortalité et sur celles de l'incapacité. La notion d'incapacité est liée aux définitions modernes de la santé, c'est-à-dire de l'adaptation de la personne ou du groupe à l'environnement. La Classification internationale des déficiences, incapacités, handicaps (CIDIH) permet l'analyse globale des incapacités et des handicaps. Il est possible d'envisager ainsi des définitions communes de la santé et de l'incapacité pour la mise au point d'instruments adaptés aux calculs de l'espérance de vie sans incapacité ou espérance de vie en santé. Il est indispensable que ce travail conceptuel soit effectué au niveau international avant l'établissement de comparaisons entre les données chiffrées d'espérance de vie en santé. De telles comparaisons ne sont licites que si les concepts et les définitions de base sont identiques.Calculation of health expectancy is based on measurements of both mortality and disability. The notion of disability is linked Lo modern definitions of health i.e. how persons or groups adapt to their environment. The International Classification of Impairments, Disabilities and Handicaps (ICIDH) provides a means to make an overall analysis of disabilities and handicaps, thus allowing us to envisage common definitions of health and disability to be used in developing instruments suitable for calculating disability-free life expectancy or health expectancy. It is essential that this development work be carried out on an international scale before going on to make comparisons between statistical data on health expectancy, since such comparisons will only be valid if the basic concepts and definitions used are the same.El calcula de la esperanza de vida en estado saludable se basa en las medidas de la mortalidad asi corno en las de la incapacidad. La noción de incapacidad està vinculada a las definiciones modemas de salud, o sea la adaptación de la persona o del grupo al medio ambiente. La Clasificación Internacional de las Deficiencias, Incapacidades, Handicaps (ClDlH) permite efectuar el anâlisis global de las incapacidades y de los handicaps. Asi, definiciones comunes de la salud y de la incapacidad pueden ayudar a implementar instrumentos que se adapten a los câlculos de la esperanza de vida sin incapacidad, o esperanza de vida, en estado saludable. Es indispensable que este trabajo conceptual se lieve a cabo a nivel internacional, antes de establecer comparaciones entre los datos cifrados de esperanza de vida en estado saludable. Dichas comparaciones no pueden ser licitas mas que si resultan idénticos los conceptos y las definiciones bâsicas