The plasma membrane abundance of the Na + /K+ pump or Na + ,K+-ATPase depends on the intracellular concentration of Na+ in almost all animal cells. In cartilage, chondrocytes are surrounded by an extracellular matrix which consists of collagen and proteoglycan, a ground substance composed of glycosaminoglycan (GAG) side chains with a high fixed negative charge density. The polyanionic nature of the GAGs tends to draw monovalent cations into the matrix resulting in high [Na + ] which may exceed 250 mM. As the concentration of GAGs in the tissue increases, so does [Na+]. In this study, it was found that the density of the Na+/K+ pump, measured by 3H-ouabain binding, correlates with the concentration of GAGs in the tissue. This indicates that chondrocytes are sensitive to their ionic environment and respond to local [Na + ] variations by regulating the abundance of the Na + /K+ pump.
Mammalian Meckel´s cartilage is a temporary structure
associated with mandible development. Notably, its elimination is
not executed by apoptosis, and autophagy was suggested as the
major mechanism. Simultaneous reports point to pro-apoptotic
caspases as novel participants in autophagic pathways in general.
The aim of this research was to find out whether activation of
pro-apoptotic caspases (-2, -3, -6, -7, -8 and -9) was associated
with autophagy of the Meckel´s cartilage chondrocytes. Active
caspases were examined in serial histological sections of mouse
mandible using immunodetection and were correlated with
incidence of autophagy based on Beclin-1 expression. Caspase-2
and caspase-8 were found in Beclin-1 positive regions, whereas
caspase-3, -6, -7 and -9 were not present. Caspase-8 was further
correlated with Fas/FasL and HIF-1α, potential triggers for its
activation. Some Fas and FasL positivity was observed in the
chondrocytes but caspase-8 activation was found also in FasL
deficient cartilage. HIF-1α was abundantly present in the
hypertrophic chondrocytes. Taken together, caspase-8 activation
in the Meckel´s cartilage was demonstrated for the first time.
Caspase-8 and caspase-2 were the only pro-apoptotic caspases
detected in the Beclin-1 positive segment of the cartilage.
Activation of caspase-8 appears FasL/Fas independent but may
be switched on by HIF-1α.
Patients treated for knee disorders were included in this study. They were examined clinically (Lequesne and Tegner scores) and by standard X-ray investigation. Patients underwent a surgical procedure, either arthroscopy or knee replacement. At the initial phase of surgery, a sample of cartilage was taken for laboratory examination. Progression of the disorder and the clinical examination was correlated with the actual state of the cartilage using a novel fluorescence approach. The intrinsic fluorescence of cartilages was shown as a suitable and sensitive method for detection of the actual state of cartilages because the correlation with X-ray examination and clinical status was found. Intrinsic fluorescence properties of cartilages from patients with chondropathy and osteoarthritis were described and found to be age-dependent. We also observed a higher concentration of advanced glycation end products due to inflammatory and/or degenerative processes in the cartilage. In addition, acute pathological changes due to diseases such as meniscal lesions or anterior cruciate ligament rupture caused a significant increase of formation of advanced glycation end products even in the group of young patients. In fact, such an observation could be crucial and important for the detection of knee conditions suspected of early meniscal and/or ACL lesions especially among young patients., M. Handl, E. Filová, M. Kubala, Z. Lánský, L. Koláčná, J. Vorlíček, T. Trč, M. Pach, E. Amler., and Obsahuje bibliografii a bibliografické odkazy
The effect of oral supplementation with glycosaminoglycans (GAG) and radical scavengers (vitamin E/selenium) on the regeneration of osteochondral defects was investigated in rabbits. After introduction of defined osteochondral defects in the knee joint, groups of ten animals were given a GAG/vitamin E/selenium mixture or a placebo (milk sugar) for 6 weeks. Following sacrifice, histological and histochemical analysis was performed. The amount of synovial fluid was increased in the placebo group, while the viscosity of the synovial fluid was significantly enhanced in the GAG group. The amount of sulfated GAG in the osteochondral regenerates (8.8±3.6 % vs. 6.0±5.6 %; p<0.03) was significantly higher in the GAG group. In both groups, the GAG amount in the cartilage of the operated knee was significantly higher than in the non-involved knee (p<0.05). Histological analysis of the regenerates in the GAG group was superior in comparison with the placebo group. For the first time, a biological effect following oral supplementation with GAG was demonstrated in healing of osteochondral defects in vivo. These findings support the known positive clinical results., M. Handl, E. Amler, K. Bräun, J. Holzheu, T. Trč, A. B. Imhoff, A. Lytvynets, E. Filová, H. Kolářová, A. Kotyk, V. Martínek., and Obsahuje bibliografii a bibliografické odkazy
Computed tomography (CT) is an effective diagnostic modality for three-dimensional imaging of bone structures, including the geometry of their defects. The aim of the study was to create and optimize 3D geometrical and real plastic models of the distal femoral component of the knee with joint surface defects. Input data included CT images of stifle joints in twenty miniature pigs with iatrogenic osteochondrosis-like lesions in medial femoral condyle of the left knee. The animals were examined eight and sixteen weeks after surgery. Philips MX 8000 MX and View workstation were used for scanning parallel plane cross section slices and Cartesian discrete volume creation. On the average, 100 slices were performed in each stifle joint. Slice matrices size was 512 x 512 with slice thickness of 1 mm. Pixel (voxel) size in the slice plane was 0.5 mm (with average accuracy of ± 0.5 mm and typical volume size 512 × 512 × 100 voxels). Three-dimensional processing of CT data and 3D geometrical modelling, using interactive computer graphic system MediTools formerly developed here, consisted of tissue segmentation (raster based method combination and 5 % of manual correction), vectorization by the marching-cubes method, smoothing and decimation. Stifle- joint CT images of three individuals of different body size (small, medium and large) were selected to make the real plastic models of their distal femurs from plaster composite using rapid prototyping technology of Zcorporation. Accuracy of the modeling was ± 0.5 mm. The real plastic models of distal femurs can be used as a template for developing custom made press and fit scaffold implants seeded with mesenchymal stem cells that might be subsequently implanted into iatrogenic joint surface defects for articular cartilage-repair enhancement., P. Krupa, P. Kršek, M. Javorník, O. Dostál, R. Srnec, D. Usvald, P. Proks, H. Kecová, E. Amler, J. Jančář, P. Gál, L. Plánka, A. Nečas., and Obsahuje bibliografii