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PubMed1993

Non-electrostatic factors govern the hydrodynamic properties of articular cartilage proteoglycan.

The hydrodynamic frictional resistance to water flow exerted by articular cartilage proteoglycan is shown to be similar to that of proteoglycan isolated from Swarm rat chondrosarcoma, and independent of the state of aggregation of the proteoglycan. Frictional resistance is dependent, however, on the chain segments of the constituent chondroitin-sulphate and keratan-sulphate chains of the proteoglycan. Frictional resistance offered by chondroitin sulphate was independent of pH over the range 3.2-8.7. This confirms previous studies, associated with varying ionic strength and chemical modification of ionic groups of chondroitin sulphate, which showed that the frictional resistance offered by this molecule is independent of electrostatic factors. Water-structure-breaking and hydrogen-bond-breaking solvents were also without major effects on the flow resistance offered by chondroitin sulphate. An overall secondary structure of chondroitin sulphate was not evident, as it showed no significant difference to dextran in terms of its temperature dependence of relative viscosity. Local regions of rigid secondary structure, as manifested through inter-residue hydrogen bonding between sugar residues, is likely to control flow resistance as periodate-oxidized chondroitin sulphate and periodate-oxidized and reduced preparations showed a significant decrease in their frictional resistance to water.

Animals↗
PubMedDate not supplied

[Comparative histomorphometry of subchondral bone density and articular cartilage thickness in the tibial head in early human arthritis].

The articular cartilage thickness and subchondral bone density of 50 human tibial heads were histomorphometrically measured by an image analysing system and topographically examined in relation to age, sex and grade of osteoarthrosis (OA). Altogether we evaluated 12,000 items. Independent of OA the lateral tibial plateau shows a significant thicker cartilage layer than the medial. In central joint areas we find a thicker cartilage cover than in marginal. Corresponding to the literature cartilage fibrillation according to OA grade 1 and 2 (Otte 1969, Fassbender 1975) accumulates in the lateral and dorsal tibial head including the meniscus covered area. The cartilage thickness decreases with age independent of OA. Without major alterations of the topographical pattern the cartilage thickness however shows a significant increase in early OA (grade 1). For that reason measurements of the cartilage thickness and joint space narrowing are not appropriate for defining early OA. The subchondral bone density shows high values ventromedially and dorsolaterally independent of sex, age or OA. Beneath central joint areas higher values are found than marginally. Corresponding to the topical literature our results point at the model of the real loaded knee joint, which says that the mean loading forces do not act on the middle of the joint but on the medial plateau. The dorsolateral density centre could be an expression of the functional adaptation of the bended knee joint. In joint areas with cartilage fibrillation (OA grade 1) we find a significant higher subchondral bone density without major alterations of the topographical pattern. It is not possible to define cause and effect, we interpret both as result of higher joint loading.

Adolescent↗
PubMed2001

Articular cartilage and changes in arthritis: matrix degradation.

While many proteases in articular cartilage have been described, current studies indicate that members of two families of metalloproteases - MMPs and the ADAMTSs - are responsible for the degradation of the major components of this tissue. Collagenases (MMPs) make the first cleavage in triple-helical collagen, allowing its further degradation by other proteases. Aggrecanases (ADAMTSs), in conjunction with other MMPs, degrade aggrecan, a component of the proteoglycan aggregate. Antineoepitope antibodies that recognize the cleavage products of collagen and aggrecan generated by these enzymes are now available and are being used to detect the sites of action and to quantitate degradation products.

Arthritis↗
PubMedDate not supplied

[The effect of temperature on preservation of swine articular cartilage--an NMR study].

The influence of temperature on stored porcine articular cartilage was studied and the factors underlying degradation identified. For these investigations, specimens measuring 18 mm in diameter were punched out of the articularis humeri of juvenile pigs. These samples were investigated by MR microimaging immediately after preparation, and after storage for three days at +4 degrees C and -18 degrees C. Five smaller (3 mm) cylindrical specimens were then obtained and compared with one another using MR-spectroscopy, relaxometry and biochemical assays. From the experiments we conclude that all analytical methods--with the exception of MR microimaging--are capable of detecting changes in cartilage, and that it is not advisable to keep cartilage frozen, since marked changes, presumably at the cellular level, occur. Storage at +4 degrees C also requires the use of preserving chemicals, as otherwise, the polymers of the extracellular matrix degrade.

Animals↗
PubMed1998

Localization of carboxy-terminal type II procollagen peptide (pCOL-II-C) and type II collagen in the repair tissue of full-thickness articular cartilage defect.

It is well established that a full-thickness articular cartilage defect is repaired with a fibrocartilaginous tissue of which cells are derived from undifferentiated mesenchymal stem cells in the bone marrow. To characterize the repair tissue immunohistochemically, full-thickness defects were created in rabbit knee joints, and the repair tissues immunostained at 3, 6, and 12 weeks after surgery. Well characterized polyclonal antibody against carboxyterminal type II procollagen peptide (pCOL-II-C) and monoclonal antibody against type II collagen were used to evaluate the repair tissue with regard to the metabolism of type II collagen. Immunohistochemistry revealed that pCOL-II-C was localized in or around most of the repair cells obtained at 3 and 6 weeks after surgery, while type II collagen distributed mainly in the pericellular matrix of metaplastic round-shaped repair cells. The results suggest that the repair cells taken at the early stage of the repair process of the defect could originally have more activity of type II collagen synthesis.

Animals↗
PubMed2005

Extracellular matrix of ostrich articular cartilage.

The composition and organization of the extracellular matrix of ostrich articular cartilage was investigated, using samples from the proximal and distal surfaces of the tarsometatarsus. For morphological analysis, sections were stained with toluidine blue and analyzed by polarized light microscopy. For biochemical analysis, extracellular matrix components were extracted with 4 M guanidinium chloride, fractionated on DEAE-Sephacel and analyzed by SDS-PAGE. Glycosaminoglycans were analyzed by electrophoresis in agarose gels. Structural analysis showed that the fibrils were arranged in different directions, especially on the distal surface. The protein and glycosaminoglycan contents of this region were higher than in the other regions. SDS-PAGE showed the presence of proteins with molecular masses ranging from 17 to 121 kDa and polydisperse components of 67, 80-100, and 250-300 kDa in all regions. The analysis of glycosaminoglycans in agarose-propylene diamine gels revealed the presence of only chondroitin-sulfate. The electrophoretic band corresponding to putative decorin was a small proteoglycan containing chondroitin-sufate and not dermatan-sulfate, unlike other cartilages. The higher amounts of proteins and glycosaminoglycans and the multidirectional arrangement of fibrils seen in the distal region may be correlated with the higher compression normally exerted on this region.

Animals↗
PubMed1987

The impact of protein size and charge on its retention in articular cartilage.

The interaction of several globular proteins with intact murine hyaline articular cartilage was studied in vitro. Proteins with molecular weights from 12 to 440 kDa and isoelectric points (pI) from 4.5 to 10 were tested for the ability to penetrate and persist in cartilage. Native proteins were modified for a range of pI. Using radiolabeled proteins we showed that retention of proteins in cartilage is a function of their pI. At pI 8.5-9 all proteins showed a sharp increase in cartilage when incubated at physiologic pH. The molecular weight of a protein and its charge is a determining factor for penetration of cartilage. By autoradiography highly cationic proteins up to 150 kDa (IgG) readily penetrated cartilage. Immunofluorescence confirmed these findings. Cationic catalase (240 kDa) showed superficial penetration, but penetration of cationic ferritin (440 kDa) was not demonstrated, suggesting that 240 to 440 kDa represents the upper range for penetration. Small anionic proteins (cytochrome-c; pI less than 4.5; 12 kDa) penetrate in small quantities but do not persist, whereas larger anionic proteins (IgG; pI less than 4.5; 150 kDa) cannot penetrate at all. Our data help define the properties of proteins that are able to interact with cartilage matrix and chondrocytes.

Animals↗
PubMed1988

Radiologic vignette: primary disorders of articular cartilage in childhood.

We discuss several less well recognized disorders of articular cartilage which may affect pediatric patients, including relapsing polychondritis, idiopathic chondrolysis of the hip and chondrolysis after slipped capital femoral epiphysis. Idiopathic osteolysis is not considered in our review because it has been well described previously.

Arthrography↗
PubMed1987

Structural changes in the proteoglycans of human articular cartilage during aging.

The structure of the aggregating proteoglycans from human articular cartilage changes continuously from the early fetus to the mature adult, due to variation in both synthetic and degradative processes. The changes due to synthesis are most prominent prior to the end of growth, and are responsible for variations in the structure and abundance of the glycosaminoglycan chains. In contrast, the changes due to degradation occur throughout life, but predominate during aging of the adult. They result in proteolytic fragmentation of both the proteoglycan subunits and the link proteins, with those products possessing hyaluronic acid-binding capability accumulating in the tissue.

Adult↗
PubMed1985

Deposition of fibronectin in articular cartilage of canine osteoarthritic joints.

Deposition of fibronectin was examined in articular cartilage of healthy and osteoarthritic joints of Labrador Retriever dogs. Abnormal cartilage from osteoarthritic joints contained up to 20 times more fibronectin than did disease-free cartilage. Compared with normal cartilage, the rate of fibronectin synthesis in osteoarthritic cartilage was increased and a greater proportion of the newly made fibronectin accumulated in the lesion cartilage matrix. The rate of release of endogenous prelabeled [3H]fibronectin from disease-free explants was similar to the rate of release from degenerated cartilage explants into incubation media. Concentrations of fibronectin were greater in synovial fluid from osteoarthritic joints than in synovial fluid from healthy joints, but both types of fluid had less fibronectin than in blood plasma.

Animals↗
PubMed1976

The resurfacing of adult rabbit articular cartilage by multiple perforations through the subchondral bone.

The repair of articular cartilage removed from the femora of adult rabbits at the knee was studied. When multiple perforations were made through the subchondral bone a cartilaginous material, staining heavily with safranin O, first filled the holes. This material resembled hyaline cartilage, and by twelve months there was complete resurfacing of the joint, although the material lost its hyaline appearance after eight months and at one year it resembled dense collagenous tissue.

Animals↗
PubMed1976

Long-term effects of chondrocyte death on rabbit articular cartilage in vivo.

The effects of freezing localized areas of rabbit articular cartilage in vivo were studied at two to twelve months morphologically (gross and microscopic examination, including scanning electron microscopy), histochemically (toluidine blue and safranin O), and metabolically (35S uptake). Up to six months the frozen cartilage was intact but appeared to be dead, as shown by the absence of stainable chondrocytes, severely decreased acid mucopolysaccharide content, and absence of significant uptake of 35S. At twelve months fibrillation and softening were evident, clusters of new chondrocytes with surrounding acid mucopolysaccharides were visible microscopically, and scanning electron microscopy revealed an irregular pattern of collagen fibers which were larger than normal, of varying thickness, and broken in some areas. These changes resembled those seen in degenerative joint disease.

Animals↗
PubMedDate not supplied

[Amino acid composition of proteoglycan protein of human articular cartilage in normal conditions and in degeneration].

Proteoglycan protein of human articular cartilage is found to contain a considerable amount of leucine, proline, glutaminic acid and glycine. The amino acid composition of various proteoglycan fractions differs in the methionine content. Proteoglycan protein from the degeneratively changed cartilage contains a less amount of lysine and serine. It is supposed that the found changes may be induced by the atypical synthesis of the proteoglycan protein shaft by chondrocytes under the cartilage degeneration.

Amino Acids↗
PubMed1983

Isolation and partial characterization of low density proteoglycans from bovine articular cartilage.

Low density proteoglycans (PG-III) were isolated from bovine articular cartilage by extraction with 4 M guanidinium chloride followed by sedimentation in a dissociative CsCl density gradient and fractionation by chromatography on DEAE-cellulose and Sepharose CL-6B columns. The PG fractions obtained were analyzed to determine the amino acid composition, the content of sulfate and carbohydrate constituents, the molecular weight, and sedimentation properties under associative and dissociative conditions and the types of glycosaminoglycan components. The results show that the major type of low density PG in adult bovine metacarpophalangeal cartilage is a proteochondroitin sulfate with a Mr approximately 44,000. A single glycosaminoglycan component was detected following alkaline borohydride cleavage that was completely digested by chondroitinase ABC treatment. The disaccharide composition of this glycosaminoglycan was 4% O-sulfate, 22% 6-sulfate, and 74% 4-sulfate. Variations were observed in the content of chondroitin sulfate and the other carbohydrate constituents, indicating that the low density PG in this tissue probably occurs as a family of molecules with a variable composition. Sedimentation velocity analysis showed that under associative conditions PG-III formed high molecular weight complexes by self-association.

Amino Acids↗
PubMedDate not supplied

Aspects of ankylosing spondylarthritis immunopathogenesis correlated with some immunoseric- and synovial parameters in the investigation of histopathological and electronmicroscopic alterations of the articular cartilage correlated with some immunoseric and synovial parameters.

Eighteen biopsies of articular cartilage taken intraoperatory from patients with Ankylosing Spondylarthritis (AS) and from others with traumatisms (controls) were investigated using histopathological (HE, VG, PAS-Alcian, Gömöri, Safranin 0), electronmicroscopic and histoenzymamologic techniques. Histopathologically, the synovitis in AS is characterized by abundant synovia lymphoplasmocytic infiltrates associated with aspects of vascular hyperplasia and fibrosis. At the pannus synovia-cartilage junction we found the invasive synovia lymphoplasmocytic infiltrates. The proteoglycan (PG) depletion is confirmed histopathologically by diminishing the Safranin 0 staining, then ultrastructurally by the existence of collagen revealing areas, whereas biochemically, by the presence of glycosaminoglycans (GAG) in serum and synovial fluid (SF). The morphological data were related to some immunological parameters involved in pathogenesis. In this way, we found pathological values of the immune circulating complexes (ICC) (serum, mean = 73.5 U; SF mean = 81.80 U) and of anti Collagen II antibodies (serum mean = 410 U; SF mean = 436 U). The reactive protein C acting in the phase (CRP) showed high pathological values both in serum (mean = 5.01 mg%) and in SF (mean = 3.6 mg%) of the patients with AS, emphasizing the inflammatory characteristics of the rheumatic disease. The presence of ICC, anticollagen II antibodies and GAS as well in synovia suggests that the inflammatory articulation in AS is a local potential antigen of collagen and proteoglycan nature.

Cartilage, Articular↗
PubMed1997

A non-invasive technique for 3-dimensional assessment of articular cartilage thickness based on MRI. Part 2: Validation using CT arthrography.

Established methods for the measurement of articular cartilage thickness are invasive and cannot be sequentially applied in living subjects. In the present study, the distribution of cartilage thickness throughout entire joint surfaces was determined from MR images obtained with a fat-suppressed gradient-echo sequence at a resolution of 0.31 x 0.31 x 2.00 mm3, and compared to that derived from CT arthrography. A minimal distance algorithm was employed to produce 3D cartilage thickness maps of seven cadaveric human knee joints. The mean amount of deviation of the cartilage volumes was 5.6% (+/- 4.6), statistical analysis showing that there was high agreement between the two methods (r = 0.995, slope = 1.037, y-intercept = -90.5 mm3). The 3D thickness maps yielded a striking agreement between the two methods, the maximum values generally yielding a deviation of none or one thickness interval of 0.5 mm. This investigation shows that accurate 3D assessment of articular cartilage thickness can be performed with MRI, this technique having the advantage that it is suitable for investigating living subjects.

Adult↗
PubMed2001

Quantitative and qualitative assessment of articular cartilage in the goat knee with magnetization transfer imaging.

We investigated the role of collagen in the magnetization transfer (MT) effect in contrast to other macromolecules. By means of phantoms made of collagen, chondroitin sulfate (CS) and albumin, MR parameters have been optimized in order to reduce the acquisition time and improve the sensitivity, as well as to minimize the contributions from CS and albumin to the MT induced signal attenuation. The same method was used to study cartilage ex vivo (bovine articular and nasal cartilage plugs) and in vivo (goat knee femoral chondyle). In phantom samples, the MT signal attenuation depended on the collagen concentration while contributions from the other macromolecules were found to be minimal. In average, analysis of MT images revealed a approximately 25%, approximately 35% and approximately 30% signal attenuation in 10% w/v type I collagen gels, cartilage plugs, and cartilage from the weight-bearing areas of the goat knee, respectively. Biochemical data revealed that treatment of cartilage plugs with bacterial collagenase led to collagen depletion and correspondingly to a decrease of the MT response. In contrast, trypsin-induced proteoglycan loss in cartilage plugs did not alter the MT effect. A significant correlation was observed between the collagen content in these plugs and their respective MT ratios and the rate constant k for the exchange process bound versus free water. Finally, data obtained from in vivo MT measurement of the goat knee demonstrated that intra-articular injection of papain might not only cause degradation of proteoglycans but also a change in collagen integrity in a dose-dependent manner. We conclude that in vivo measurement of MT ratios gives quantitative and qualitative information on the collagen status and may be applied for the routine evaluation of normal and abnormal articular cartilage.

Animals↗
PubMed1997

Regeneration of articular cartilage defects in rabbits by osteogenic protein-1 (bone morphogenetic protein-7).

Osteogenic protein-1 (OP-1, BMP-7), a member of the transforming growth factor-beta family, induces cartilage and bone formation when implanted at intra and extraskeletal sites in vivo. The human OP-1 gene has been cloned and biologically active recombinant OP-1 homodimers have been produced. In the present study, the authors investigated the influence of OP-1 on healing of full-thickness articular cartilage defects, made by drilling two adjacent (phi 3mm) holes through articular cartilage of NZW rabbit knee joint were dissected and examined histomorphometrically. Results indicated that OP-1 induced articular cartilage healing and regeneration of the joint surface which contained cells resembling mature joint chondrocytes. These data imply a new strategy for biological repair of damaged joint surfaces in humans.

Animals↗