The effects of tackle height on inertial loading of the head and neck in Rugby Union: A multibody model analysis

Objective: There is evidence of chronic injury to the head-and-neck region of Rugby Union players. The aim of this study was to use multibody simulations to examine the effects of tackle height on both Tackler and Ball Carrier head kinematics and neck dynamics. Research Design: Quantitative Exploratory Study Methods and procedures: 45 front-on shoulder tackles with no direct contact to the head/neck were simulated with the MADYMO pedestrian model and used to assess differences between upper body tackles and lower body tackles. The average resultant head linear and angular accelerations as well as neck forces and moments were assessed. Main outcomes and results: Much higher Ball Carrier head kinematic values and neck loading were predicted for upper body tackles compared to lower body tackles, and principal findings were unaffected by a sensitivity analysis. Tackler results were less straightforward and trends were influenced by the sensitivity analysis for muscle activation. Conclusion: Although further model validation is required, the results of this study indicate the need for further research on tackle heights and inertial head-and-neck loading in the tackle phase of play in Rugby Union

Identification, partial purification and characterization of high-molecular-weight gelatin-degrading metalloproteinases produced by a rat mammary carcinoma cell line

International audienceBC1 rat mammary carcinoma cells were found to secrete a unique profile of metalloproteinases, distinguished by two gelatin-degrading metalloproteinases of Mr greater than 220.10(3) and Mr much greater than 220.10(3). These enzymes were each partially purified by gel-filtration chromatography, and inhibitor studies showed them to be metalloproteinases. Under conditions where denatured collagen types I, II, and V were completely degraded, native collagen types I, II, IV and V, fibronectin, fibrinogen, C1q, casein, and denatured transferrin were not degraded significantly by these enzymes. The relationship of these enzymes to other extracellular matrix-degrading metalloproteinases and their possible significance in tumour invasion and metastasis is discussed

Proteolytic control of TGF-β co-receptor activity by BMP-1/tolloid-like proteases revealed by quantitative iTRAQ proteomics

International audienceThe metalloproteinase BMP-1 (bone morphogenetic protein-1) plays a major role in the control of extracellular matrix (ECM) assembly and growth factor activation. Most of the growth factors activated by BMP-1 are members of the TGF-β superfamily known to regulate multiple biological processes including embryonic development, wound healing, inflammation and tumor progression. In this study, we used an iTRAQ (isobaric tags for relative and absolute quantification)-based quantitative proteomic approach to reveal the release of proteolytic fragments from the cell surface or the ECM by BMP-1. Thirty-eight extracellular proteins were found in significantly higher or lower amounts in the conditioned medium of HT1080 cells overexpressing BMP-1 and thus, could be considered as candidate substrates. Strikingly, three of these new candidates (betaglycan, CD109 and neuropilin-1) were TGF-β co-receptors, also acting as antagonists when released from the cell surface, and were chosen for further substrate validation. Betaglycan and CD109 proved to be directly cleaved by BMP-1 and the corresponding cleavage sites were extensively characterized using a new mass spectrometry approach. Furthermore, we could show that the ability of betaglycan and CD109 to interact with TGF-β was altered after cleavage by BMP-1, leading to increased and prolonged SMAD2 phosphorylation in BMP-1-overexpressing cells. Betaglycan processing was also observed in primary corneal keratocytes, indicating a general and novel mechanism by which BMP-1 directly affects signaling by controlling TGF-β co-receptor activity. The proteomic data have been submitted to ProteomeXchange with the identifier PXD000786 and doi: 10.6019/PXD000786