63 research outputs found
Osteoclasts Control Osteoblast Chemotaxis via PDGF-BB/PDGF Receptor Beta Signaling
BACKGROUND: Bone remodeling relies on the tightly regulated interplay between bone forming osteoblasts and bone digesting osteoclasts. Several studies have now described the molecular mechanisms by which osteoblasts control osteoclastogenesis and bone degradation. It is currently unclear whether osteoclasts can influence bone rebuilding. METHODOLOGY/PRINCIPAL FINDINGS: Using in vitro cell systems, we show here that mature osteoclasts, but not their precursors, secrete chemotactic factors recognized by both mature osteoblasts and their precursors. Several growth factors whose expression is upregulated during osteoclastogenesis were identified by DNA microarrays as candidates mediating osteoblast chemotaxis. Our subsequent functional analyses demonstrate that mature osteoclasts, whose platelet-derived growth factor bb (PDGF-bb) expression is reduced by siRNAs, exhibit a reduced capability of attracting osteoblasts. Conversely, osteoblasts whose platelet-derived growth factor receptor beta (PDGFR-beta) expression is reduced by siRNAs exhibit a lower capability of responding to chemotactic factors secreted by osteoclasts. CONCLUSIONS/SIGNIFICANCE: We conclude that, in vitro mature osteoclasts control osteoblast chemotaxis via PDGF-bb/PDGFR-beta signaling. This may provide one key mechanism by which osteoclasts control bone formation in vivo
Non-verbal behaviour in same-sex and mixed-sex physiotherapist-patient interactions
Six male and six female physiotherapists were videotaped while treating male and female patients. The average duration of the therapist's gaze, smiling, touch, and speech, as well as the ratio of therapist's to patient's speech, were computed. It was found that these non-verbal behaviours differed as a function of sex of physiotherapist, sex of patient and point in the interaction. It was suggested that physiotherapists should increase their awareness of these behaviours in their interactions with patients
Hck contributes to bone homeostasis by controlling the recruitment of osteoclast precursors
ABSTRACT In osteoclasts, Src controls podosome organization and bone degradation, which leads to an osteopetrotic phenotype in src Ű/Ű mice. Since this phenotype was even more severe in src Ű/Ű hck Ű/Ű mice, we examined the individual contribution of Hck in bone homeostasis. Compared to wt mice, hck Ű/Ű mice exhibited an osteopetrotic phenotype characterized by an increased density of trabecular bone and decreased bone degradation, although osteoclastogenesis was not impaired. Podosome organization and matrix degradation were found to be defective in hck Ű/Ű osteoclast precursors (preosteoclast) but were normal in mature hck Ű/Ű osteoclasts, probably through compensation by Src, which was specifically overexpressed in mature osteoclasts. As a consequence of podosome defects, the 3-dimensional migration of hck Ű/Ű preosteoclasts was strongly affected in vitro. In vivo, this translated by altered bone homing of preosteoclasts in hck Ű/Ű mice: in metatarsals of 1-wk-old mice, when bone formation strongly depends on the recruitment of these cells, reduced numbers of osteoclasts and abnormal developing trabecular bone were observed. This phenotype was still detectable in adults. In summmary, Hck is one of the very few effectors of preosteoclast recruitment described to date and thereby plays a critical role in bone remodeling.-VĂ©rollet, C., Gallois, A., Dacquin, R., Lastrucci, C., Pandruvada, S. M. N., Ortega, N., Poincloux, R., Behar, A., Cougoule, C., Lowell, C., Al Saati, T., Jurdic, P., Maridonneau-Parini, I. Hck contributes to bone homeostasis by controlling the recruitment of osteoclast precursors. FASEB J. 27, 3608 -3618 (2013). www.fasebj.org Key Words: osteopetrosis â
cell migration â
podosomes â
Src tyrosine kinases Bone is renewed continuously by a process known as bone remodeling. Bone remodeling is accomplished by 3 cell types: osteocytes, osteoblasts, and osteoclasts (OCs). Osteocytes are the mechanical sensors of bone that regulate osteoclast formation. Osteoblasts synthetize the matrix and promote its mineralization, while OCs are responsible for degradation of bones during bone development, homeostasis, and repair. The formation and degradation of bone are tightly balanced in both time and space. A dysregulation of this tight balance between bone formation and bone degradation may result either in loss of bone mass, such as in osteoporosis, or in contrast, in a progressive increase in bone mass, such as in osteopetrosis. Degrading OCs are large multinucleated giant cells formed by the differentiation and fusion of mononuclear monocyte lineage precursors after stimulation by receptor activator of nuclear factor -B ligand (RANKL) and macrophage colony-stimulationg factor (M-CSF) (1-3). They are characterized by high levels of cathepsin K and tartrate resistant acidic phosphatase (TRAP) activities, whic
A review of open top chamber (OTC) performance across the ITEX Network
Open top chambers (OTCs) were adopted as the recommended warming mechanism by the International Tundra Experiment (ITEX) network in the early 1990âs. Since then, OTCs have been deployed across the globe. Hundreds of papers have reported the impacts of OTCs on the abiotic environment and the biota. Here we review the impacts of the OTC on the physical environment, with comments on the appropriateness of using OTCs to characterize the response of biota to warming. The purpose of this review is to guide readers to previously published work and to provide recommendations for continued use of OTCs to understand the implications of warming on low stature ecosystems. In short, the OTC is a useful tool to experimentally manipulate temperature, however the characteristics and magnitude of warming varies greatly in different environments, therefore it is important to document chamber performance to maximize the interpretation of biotic response. When coupled with long-term monitoring, warming experiments are a valuable means to understand the impacts of climate change on natural ecosystems
Delayed HIV diagnosis and initiation of antiretroviral therapy: inequalities by educational level, COHERE in EuroCoord.
OBJECTIVES
In Europe and elsewhere, health inequalities among HIV-positive individuals are of concern. We investigated late HIV diagnosis and late initiation of combination antiretroviral therapy (cART) by educational level, a proxy of socioeconomic position.
DESIGN AND METHODS
We used data from nine HIV cohorts within COHERE in Austria, France, Greece, Italy, Spain and Switzerland, collecting data on level of education in categories of the UNESCO/International Standard Classification of Education standard classification: non-completed basic, basic, secondary and tertiary education. We included individuals diagnosed with HIV between 1996 and 2011, aged at least 16 years, with known educational level and at least one CD4 cell count within 6 months of HIV diagnosis. We examined trends by education level in presentation with advanced HIV disease (AHD) (CD4 <200âcells/ÎŒl or AIDS within 6 months) using logistic regression, and distribution of CD4 cell count at cART initiation overall and among presenters without AHD using median regression.
RESULTS
Among 15â414 individuals, 52, 45,37, and 31% with uncompleted basic, basic, secondary and tertiary education, respectively, presented with AHD (P trend <0.001). Compared to patients with tertiary education, adjusted odds ratios of AHD were 1.72 (95% confidence interval 1.48-2.00) for uncompleted basic, 1.39 (1.24-1.56) for basic and 1.20 (1.08-1.34) for secondary education (Pâ<â0.001). In unadjusted and adjusted analyses, median CD4 cell count at cART initiation was lower with poorer educational level.
CONCLUSIONS
Socioeconomic inequalities in delayed HIV diagnosis and initiation of cART are present in European countries with universal healthcare systems and individuals with lower educational level do not equally benefit from timely cART initiation
SystÚmes de manutention en Europe : gouvernance, organisation et conditions de travail
Dans le cadre de lâanalyse de la conflictualitĂ© au sein des communautĂ©s portuaires en Europe, lâĂ©tude spĂ©cifique du secteur de la manutention sâavĂšre tout Ă fait pertinente. Elle peut, Ă lâoccasion, rĂ©vĂ©ler une variĂ©tĂ© Ă©tendue de situations conflictuelles, tels des conflits sociaux, domaniaux, de gouvernance, ou encore liĂ©s Ă des situations de monopole. MalgrĂ© une tendance Ă une certaine homogĂ©nĂ©isation des modes de gestion de la manutention sur de nombreux terminaux europĂ©ens, des particular..
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