Enforced exercise after blunt trauma significantly affects biomechanical and histological changes in rabbit retro-patellar cartilage

Immobilization-induced cartilage degeneration mediated through expression of hypoxia-inducible factor-1alpha, vascular endothelial growth factor, and chondromodulin-I

Immobilization results in thinning of the articular cartilage and cartilage degeneration, although the exact mechanisms are not clear yet. Hypoxia is thought to contribute to the degeneration of articular cartilage. We investigated the roles of hypoxia inducible factor (HIF)-1alpha, vascular endothelial growth factor (VEGF), and the newly cloned antiangiogenic factor, chondromodulin-I (ChM-1), in cartilage degeneration in immobilized joints. Male Wistar rats (n = 30, 12-week-old) were divided randomly into the control group (n = 10), immobilization group (n = 10), and continuous passive motion (CPM) group (n = 10). In the immobilization group, the ankle joints were fixed in full plantar flexion with plaster casts for 4 weeks. In the CPM group, the ankle casts were removed during the immobilization period and the ankle joints were subjected to CPM. Significant thinning of the articular cartilage was noted in the immobilization group but not in the control or CPM group. In the immobilized group, vascular channels were found in the area between the calcified cartilage zone and the subchondral bone. The densities of HIF-1alpha-and VEGF-immunostained cells were higher in the immobilized group than the other two groups. In contrast, low expression of ChM-1 was detected in the articular cartilage of the immobilized group compared with the control and CPM group. Our results showed that immobilization induces thinning of the articular cartilage and appearance of vascular channel, in areas with balanced expression of HIF-1alpha/VEGF and ChM-1.

Mechanical properties of polypropylene mesh used in pelvic floor repair

The aim of this study was the comparison of the stiffness of different meshes under two types of mechanical tests. Five different mesh types were mechanically tested. The methods used consisted on uniaxial tension test (tensile stiffness) and tape ring tests, experimental continuous compression of the mesh loops (flexural stiffness). The most significant difference of tensile stiffness behaviour appears between Aris and TVTO. From the analysis of the experimental data, we divided the flexural stiffness, in two main groups. The first group includes Auto Suture and Aris meshes. The two meshes seem to have a similar flexural behaviour. The second group includes TVTO, Uretex and Avaulta. The difference between these two groups is clearly evident comparing TVTO and Aris. This study shows that there are significant differences on the mechanical properties between urogynecology meshes.

The mechanical response of human liver and its relation to histology: an in vivo study

The mechanical response of human liver is characterized in vivo by means of intra-operative aspiration experiments. Mechanical characterization is combined with histological evaluation of liver tissue biopsies obtained from the resected liver at the site of mechanical testing. This procedure enables a quantitative analysis of the correlation between mechanical response and tissue micro-structure of normal and diseased liver. Ten organs were tested in vivo at multiple locations, as well as ex vivo immediately after resection. Biopsies were analyzed in terms of pathology and percentage of connective tissue content. The change of the mechanical parameters from in vivo to ex vivo has been determined, with an increase of 17% of the proposed stiffness index. The relationship between mechanical parameters and various pathologic conditions affecting the tissue samples has been quantified, with fibrosis leading to a response up to three times stiffer as compared with normal tissue. Increased stiffness can be detected by digital palpation (increased "consistency") and may suggest the presence of a tumor. The present observations suggest that stiffness increase cannot be attributed to the tumoral tissue itself, but rather to the fibrotic stroma that often arise within or adjacent to the tumor. Variation of the mechanical parameters as a function of connective tissue content has been evaluated based on the histological examinations and the results confirm a direct proportionality between stiffness index and connective tissue percentage. The approach described here might eventually lead to a diagnostic procedure and complement other clinical methods, like palpation and ultrasound examination of the liver.