Characterization of Thermo-Mechanical and Fracture Behaviors of Thermoplastic Polymers

In this paper the effects of the strain rate on the inelastic behavior and the self-heating under load conditions are presented for polymeric materials, such as polymethyl methacrylate (PMMA), polycarbonate (PC), and polyamide (PA66). By a torsion test, it was established that the shear yield stress behavior of PMMA, PC, and PA66 is well-described by the Ree-Eyring theory in the range of the considered strain rates. During the investigation, the surface temperature was monitored using an infrared camera. The heat release appeared at the early stage of the deformation and increased with the strain and strain rate. This suggested that the external work of deformation was dissipated into heat so the torsion tests could not be considered isothermal. Eventually, the effect of the strain rate on the failure modes was analyzed by scanning electron microscopy.     

Aortic valve replacement in the elderly

We report a retrospective study about 60 patients operated on for aortic valve replacement between 1981 and 2000. All patients were aged more than 65 years. 56.6% of patients were in the class III or IV of the NYHA. The type of the valvular substitute was a mechanical prostheses in 58.3% of cases and a biological prostheses in 41.7%. A mitral geste was associated in 6 cases and a myocardial revascularisatin in 5 cases. The early mortality rate was 15% and the late mortality was 23%. The high mortality is meanly related to the associate lesions (coronaropathy) and the prognosis is a better with the improvement of surgical technics and perioperative management.     

Palmar-plantar fasciitis and multiple myeloma

Palmar fasciitis and arthritis was reported in association with several neoplasms and in particular with the cancers of the ovary. We report the case of a 37 year old patient who was hospitalized in our service for investigation of sever palmar fasciitis and to whom various investigations allowed to make the diagnosis of a light chains myeloma. Through the study of the various cases of the literature, we remind the various characteristics of this syndrome.     

New Markers of Bone Fragility in Hemodialysis Patients: A Monocentric Study

Introduction: Mechanisms underlying bone fragility in patients under dialysis are various. The assessment of bone disorder is not yet codified in these patients. Our study aimed to determine the relationship between the serum fibroblast growth factor 23 (FGF23) level and bone fragility. We also aimed to assess the bone alkaline phosphatase (bAP) to the C-terminal telopeptide of type I (CTX) ratio and the FGF23*bAP product to CTX ratio in patients under hemodialysis. Methodology: We conducted a cross-sectional study, including 76 patients under hemodialysis. To assess bone fragility, we measured bAP, CTX, and FGF 23. We calculated the bAP to the CTX ratio (bAP/CTX) and the FGF23*bAP product to the CTX ratio (FGF23*bAP/CTX). We defined bone fragility as the existence of osteoporosis or fragility fractures. Receiver operating characteristic (ROC) curves were evaluated for each biological using the existence of osteoporosis or fragility fracture as the gold standard for bone fragility. Results: There were 51 men. The mean age was 53.36 ± 14.27 years. Bone fragility was noted in 25 cases. Patients with osteoporosis had higher FGF*bAP/CTX and bAP/CTX ratios. The ability of the ratio (bAP/CTX) to distinguish patients with osteoporosis from those without osteoporosis was good, with a ROC AUC of 0.707. The optimal ratio cut-off value with the highest accuracy was 9.72. The ability of the ratio (FGF23*bAP/CTX) to distinguish patients with bone fragility was good, with a ROC AUC of 0.701. The optimal ratio cut-off value with the highest accuracy was 1621.89 (sensitivity 60%, specificity 78.4%). Conclusion: Our study showed FGF23, FGF23*bAP product to CTX ratio, and the bAP to CTX ratio can be used as markers of bone fragility in hemodialysis patients. Therefore, these noninvasive and relatively inexpensive methods may serve to diagnose bone fragility in patients under hemodialysis.     

Hydatid cyst of the adductor muscles. MRI aspect, Apropos of 1 case

Muscular involvement is rare, representing less than 1% of hydrated cyst localisation's. Clinical symptoms are insidious and non-specific causing a frequent delay in diagnosis. We report the observation of a 50 year-old woman consulting for inguinal tumefaction with radiological exploration suggestive of hydrated cyst of adductors muscles. Magnetic resonance imaging is helpful in diagnosis, since it reveals a very suggestive aspect. Treatment is based on surgery, which cures patients but incurs a low risk of local relapse.     

Acute transverse myelitis revealing ankylosing spondylitis: A case report and literature review

When faced with a patient with acute myelopathy, thorough investigations should be undertaken to determine the cause. Ankylosing spondylitis should be kept in mind as a possible cause.     

Caveolin plays a central role in endothelial progenitor cell mobilization and homing in SDF-1-driven postischemic vasculogenesis

When neovascularization is triggered in ischemic tissues, angiogenesis but also (postnatal) vasculogenesis is induced, the latter requiring the mobilization of endothelial progenitor cells (EPC) from the bone marrow. Caveolin, the structural protein of caveolae, was recently reported to directly influence the angiogenic process through the regulation of the vascular endothelial growth factor (VEGF)/nitric oxide pathway. In this study, using caveolin-1 null mice (Cav(-/-)), we examined whether caveolin was also involved in the EPC recruitment in a model of ischemic hindlimb. Intravenous infusion of Sca-1(+) Lin(-) progenitor cells, but not bone marrow transplantation, rescued the defective neovascularization in Cav(-/-) mice, suggesting a defect in progenitor mobilization. The adhesion of Cav(-/-) EPC to bone marrow stromal cells indeed appeared to be resistant to the otherwise mobilizing SDF-1 (Stromal cell-Derived Factor-1) exposure because of a defect in the internalization of the SDF-1 cognate receptor CXCR4. Symmetrically, the attachment of Cav(-/-) EPC to SDF-1-presenting endothelial cells was significantly increased. Finally, EPC transduction with caveolin small interfering RNA reproduced this advantage in vitro and, importantly, led to a more extensive rescue of the ischemic hindlimb after intravenous infusion (versus sham-transfected EPC). These results underline the critical role of caveolin in ensuring the caveolae-mediated endocytosis of CXCR4, regulating both the SDF-1-mediated mobilization and peripheral homing of progenitor cells in response to ischemia. In particular, a transient reduction in caveolin expression was shown to therapeutically increase the engraftment of progenitor cells.