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At least 19 recordsLinked to original sources
PubMed1976

Metalloproteases of human articular cartilage that digest cartilage proteoglycan at neutral and acid pH.

Extracts of human articular cartilage contain proteases capable of degrading the proteoglycan component of cartilage matrix at neutral and acid pH. These enzymes have been partially purified by ion exchange chromotography and characterized by disc electrophoresis, inhibition patterns, and action of proteoglycan. Three distinct metalloproteases are described. A neutral protease that digests proteoglycan subunit optimally at pH 7.25 has been purified up to 900-fold. It is strongly inhibited by o-phenanthroline, alpha-2-macroglobulin, and egg white, and to a lesser extent by D-penicillamine and EDTA. Inhibition by chelating agents is reversed by cobalt, zinc, and ferrous ions. Two acid metalloproteases, distinct from cathespins B1, D, and F, digest proteoglycan subunit at pH 4.5 and 5.5. Both are inhibited by o-phenanthroline and activity is restored by cobalt, zinc, or ferrous ions. With electron microscopy, it was found that cartilage slices were depleted of ruthenium red-staining matrix proteoglycan after incubation in vitro with a partially purified cartilage extract at neutral pH. Sedimentation, gel chromatography, sodium dodecyl sulfate-gel electrophoresis, and immuno-diffusion studies of digests of isolated proteoglycan fraction produced by the partially purified cartilage extract at neutral and acid pH confirmed that the cartilage enzymes act only on the protein component of proteoglycan subunit, producing fragments with 5 to 12 chondroitin sulfate chains. The link proteins were not digested.

Cartilage, Articular↗
PubMed2025

Localisation-Dependent Variations in Articular Cartilage ECM: Implications for Tissue Engineering and Cartilage Repair.

Articular cartilage (AC) is a specialised connective tissue covering joint surfaces. It enables smooth movement, distributes mechanical loads, and protects the underlying bone. In response to loading, AC adapts by modifying both its thickness and composition. AC is organised in different zones, with low cellularity and a high abundance of extracellular matrix (ECM). Mechanical overloading or immobilisation can lead to structural changes, potentially resulting in osteoarthritis (OA), for which no causal treatment currently exists. However, smaller defects can be treated using chondrocyte/cartilage transplantation or tissue engineering. A better understanding of the molecular composition of AC at different locations is essential to improve such therapeutic approaches. For this purpose, we performed a comprehensive analysis of porcine femoral knee cartilage at eight defined anatomical sites. Cartilage thickness and proteoglycan (PG) content were analysed histologically, while specific ECM proteins were assessed by proteomics and validated by immunohistochemistry and Western blot. Significant differences were identified, particularly between medial and lateral compartments, in terms of cartilage thickness, PG abundance, and ECM composition. Some proteins also showed zone-specific localisation patterns. These structural differences likely reflect adaptation to mechanical loading and should be considered to optimise future cartilage repair and tissue engineering strategies.

Extracellular Matrix↗
PubMed1976

Cathepsin D activity in bovine articular cartilage, synovial membrane and fluid: degradation of cartilage proteoglycans from same joint.

Cathepsin D type proteases were extracted from articular cartilage, synovial membrane, and synovial fluid from normal, adult bovine knee joints. A sensitive enzyme assay made it possible to measure protease activity in the different tissues from individual joints. Highest activity was found in the synovial membrane, while cell free synovial fluids contained comparatively low activity. The degrading effect on articular cartilage proteoglycans (PGC and PGS), isolated from the same joints, was demonstrated by gelfiltration on Sepharose columns and by viscometry. Gelfiltration profiles of incubation mixtures indicated a proteolytic effect on PGC and on PGS), at pH 3.5, in concentrations of enzyme and proteoglycans found in cartilage tissue. No effect at neutral pH was obtained despite a 100-fold increase of enzyme concentration. These findings were supported by viscometry data. The degrading effect of enzymes from all sources was completely inhibited by pepstatin.

Animals↗
PubMed1975

Morphological and biochemical studies during differentiation and calcification of fracture callus cartilage.

Differentiation and calcification of cartilage of a fracture callus morphologically, ultrastructurally, and histochemically resembles cartilage of growing epiphyseal plate. The fracture callus includes the various cartilage cell types found in the epiphyseal plate. Proliferating and hypertrophic cartilage had higher activities of cytochrome oxidase, alkaline phosphatase and glutamate aspartate transaminase than fibrocartilage. Enzymes controlling glycogen synthesis and glycolysis had higher levels of activity in fibrocartilage than in hypertrophic cartilage. Lysosomal enzymes, catalase, 6-phospho-gluconic acid and glucose 6-phosphate dehydrogenase were uniformly distributed. Alkaline phosphatase was associated with extracellular vesicles found in hypertrophic cartilage. EM dense granules were found in mitochondria in hypertrophic cartilage. There was an increase of total lipids in hypertropic and calcified cartilage as compared to resting cartilage.

Alcian Blue↗
PubMed1977

[Degenerative changes in the central region of aging human rib cartilage, as influenced by growing cross section diameter (author's transl)].

In the centre of aged human rib cartilage, a yellowing degenerative zone is seen, while in a circular peripheral region the tissue remains unchanged. The cartilage of the 12th rib shows decrease in diameter towards its free end. It therefore was used as a model to find out wether there is a critical diameter of the diffusion stretch leading to a degeneration of the centre. This stretch was to be compared with the diameter of the peripheral circular zone. Cartilage of the second rib was used for comparison. The length of the free end showing no degeneration was 2,5- to 4 mm. Its radius was longer than the diameter of the circular zone in the middle part of the 12th rib cartilage, but this was not found in the second rib cartilage nor at the base of the 12th rib cartilage. The difference between the cartilage of differing individuals was more striking than the difference found between all cross sections of the second and 12th rib cartilage. The length of the diffusion stretch is thought to be an accessorial cause of aging besides the age changes of the cells and intercellular matrix, but not the only cause.

Aging↗
PubMed2026

Mapping articular cartilage maturation across postnatal development by proteomics.

OBJECTIVE: Articular cartilage has a specialised extracellular matrix that provides tensile strength and resistance to compression, but repair capacity is limited. Matrix remodelling during growth is essential for long-term tissue function, yet the underlying protein-level adaptations remain poorly characterised in large-animal models relevant to human joint biology. DESIGN: Using non-targeted, label-free mass spectrometry-based proteomics, we profiled full-thickness articular cartilage from goats across seven postnatal ages from neonatal to adult (n = 3 per age). Cartilage proteins were extracted using guanidine-based solubilisation and analysed by mass spectrometry. Selected proteins were further examined by immunohistochemistry. RESULTS: We identified 799 proteins across the seven ages, of which 157 matrisome components grouped into six categories. Development was associated with increased abundance of proteins involved in matrix organisation and stabilisation, including COL6A1, LOX, TIMP3 and CILP. Enrichment analysis revealed a shift from collagen biosynthesis and fibrillogenesis in early postnatal cartilage to elastic fibre organisation, integrin-matrix interactions and glycosaminoglycan metabolism in mature tissue, consistent with transition from matrix assembly to maintenance. Lysozyme increased with age, suggesting a structural role that warrants further study. Several proteins enriched in mature cartilage, including CILP, HTRA1, FN1 and SPP1, have also been implicated in osteoarthritis, suggesting that some molecular features of mature ECM maintenance are shared with diseased tissue. Immunohistochemistry confirmed stable COL2 localisation, loss of deep-zone COL10 staining with maturation and emergence of superficial PRG4 expression in adult cartilage. CONCLUSIONS: Our findings define the proteomic trajectory of cartilage maturation and provide a molecular reference for joint development and matrix ageing.

Animals↗
PubMed2026

Association of Early Knee Extension Range of Motion Deficits With Cartilage T2 Relaxation Following Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Anterior cruciate ligament (ACL) injury significantly increases the risk for developing knee osteoarthritis (OA), yet the early contributors to cartilage degeneration remain poorly understood. While range of motion (ROM) deficits after ACL reconstruction (ACLR) are associated with long-term development of radiographic OA, the association between early ROM recovery and cartilage composition has not been established. HYPOTHESIS: Knee extension ROM deficits at 2 months after ACLR would be associated with worsening tibiofemoral and patellofemoral cartilage T2 relaxation times at 6 months. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: A total of 30 participants (15-35 years) were enrolled within 1 month of ACL injury and before ACLR. At 2 months post-ACLR, active knee extension ROM was measured in the supine position using a goniometer. An extension deficit was considered >3° less extension in the injured knee compared to the uninjured side. Quantitative magnetic resonance imaging-based T2 relaxometry of the injured knee was performed preoperatively and at 6 months post-ACLR to measure percent change in mean T2 relaxation times in predefined tibial and femoral cartilage regions. Independent t tests were used to compare changes in T2 values between participants with and without an extension deficit. RESULTS: The mean age of the participants was 18.8 ± 3.9 years, and 63.3% were female. Fifteen (50.0%) participants exhibited an extension deficit at 2 months. Those with an extension deficit demonstrated a greater increase in T2 relaxation time in the anterior (mean difference, 10.21% [95% CI, 3.67%-16.76%]; P = .003) and weightbearing (mean difference, 6.14% [95% CI, 2.19%-10.09%]; P = .004) cartilage of the medial femoral condyle. No significant group differences were observed in other cartilage regions (all P > .05). CONCLUSION: Knee extension ROM deficits at 2 months post-ACLR are associated with early compositional changes in the medial femoral cartilage, indicating a potential relationship between limited extension and OA risk.

Humans↗
PubMedDate not supplied

Electron microscopic demonstration of immunoglobulin deposition in rheumatoid cartilage.

Horseradish peroxidase (HRPO) conjugated with goat antihuman IgG, goat antihuman IgM, and aggregated human IgG has been used as a enzymatic marker to stain IgG, IgM, and rheumatoid factor in rheumatoid cartilage. When Hrpo-anti IgG and HRPO-anti IgM were used, immunoglobulin deposits were not observed in nonrheumatoid cartilage. However 7 of 8 rheumatoid cartilage specimens stained with HRPO-anti IgG showed electron-dense deposits. Three rheumatoid specimens stained with HRPO-anti IgM showed similar findings. Both of 2 rheumatoid specimens also stained positively with HRPO conjugated with aggregated IgG, a finding indicating that rheumatoid factor was present. The deposits were seen between the collagen fibers of the superficial layer of the cartilage to a maximal depth of 22 mu from the surface (average: 7 mu). The amorphous fibrinous material on the surface of the cartilage was also stained. The demonstration of IgG, IgM, and rheumatoid factor in the superficial zone of rheumatoid cartilage suggests that immune complexes are deposited in the cartilage in this disease.

Arthritis, Rheumatoid↗
PubMed1977

Occurrence of ornithine decarboxylase and polyamines in cartilage.

The activity of ornithine decarboxylase was investigated in cartilage from chick embryos, rabbits, rats and human foetuses. The enzyme activity in these cartilages was of the same order as the detected in other body tissues. Ornithine decarboxylase activity in chick-embryo cartilage and liver was the same when compared on the basis of total soluble tissue protein. The cartilage enzyme exhibited a pH optimum of 6.5 and a Km for ornithine of 0.16mM. Ornithine decarboxylase activity in chick-embryo pelvic leaflets was maintained at the value in vivo for up to 22h when the isolated tissue was incubated in a modified Waymouth's medium (MB 752/1) at 37 degrees C. After addition of cycloheximide to the incubation medium, ornithine decarboxylase activity declined, with a half-life of 40 min. The concentrations of the polyamines spermidine and spermine in chick-embryo pelvic cartilage and rabbit costal cartilage were of the same order as the concentrations detected in other tissues.

Animals↗
PubMed1975

Role of the chondrocytes in the breakdown of pig articular cartilage induced by complement-sufficient antiserum to pig erythrocytes.

Previous work showed that in organ culture pig articular cartilage is not affected by complement-sufficient antiserum to pig erythrocytes (AS plus C') unless it is associated with soft connective tissue. In the presence of synovial tissue the matrix becomes depleted of proteoglycan and may finally disintegrate. Immunoglobulin fails to enter normal cartilage matrix, but penetrates depleted matrix and reacts with the surfaces of the chondrocytes. The present experiments were made to see whether the breakdown of partially depleted cartilage matrix would progress in AS plus C' after removal of the synovial explant. Affronted explants of articular cartilage and synovial tissue were cultivated in AS plus C' for 10 days (primary cultures). The synovial tissue was then removed and the isolated cartilage maintained for a further period either in AS plus or C' or in one of a variety of control media (SECONDARY CULTURES). The behavior of the isolated cartilage during the secondary culture period depended on the degree of breakdown attained at the end of the primary period. If only proteoglycan but not collagen had been seriously depleted, degradation of the matrix did not progress in AS plus C' and slight regeneration of metachromatic materal sometimes took place; regneration of matrix was greater after transfer to control medium. If collagen as well as proteoglycan had been destrobyed, the chondrocytes assumed a fibroblastic form, their surfaces no longer reacted with IgG antibody, and in secondary culture they failed to regenerate new matrix.

Animals↗
PubMed1975

The histochemistry and structure of tentacle cartilage tissues in the marine polychaete, Sabella melanostigma.

The cartilages (or "chondroid" tissue) in tentacles of the polychaete annelid, Sabella melanostigma, have been examined by electron microscopy and a series of histochemical techniques for the demonstration of mucopolysaccharides and protein end-groups. The ultrastructural studies indicated that the cartilages possess an investing layer of dense connective tissue which differs significanly from the matrix material secreted between the chondrocytes. The cartilage matrix was positive for acidic mucins with levels of sulfation above those of mammalian chondroitins A and C. This matrix as well as the investing connective tissue were intensely PAS-positive. Sabella cartilage was also stained intensely by methods for demonstrating tryptophan, tyrosine, side-chain carboxyl groups, disulfide groups, and amino groups. It was not stained by the procedure for sulfhydryl groups. Some evolutionary aspects of cartilage and chondroid tissues were discussed.

Amino Acids↗
PubMedDate not supplied

Histochemical studies on the distribution of acidic glycosaminoglycans in human rib cartilage during the aging process.

In human cadavers of different age five zones of basic substances can be distinguished around the cartilage cell by using hyaluronidase digestion and Alcian blue stain combined with various MgC12-concentrations. This treatment produces different reactions in the various zones. The zones are numbered according to their distance from the cell; thus zone 1 (Z1 = pericellular zone) is the nearest to the cell. Z 1 and Z 2 (inner territorial zone) contain hyaluronidase-digestible substance but Z 1 stains at higher electrolyte concentrations than does Z 2. The third zone (Z 3 = outer territorial zone) which first appears in childhood always contains hyaluronidase-resistant material and, besides, hyaluronidase-digestible material in adolescence. Since the distance between the cells increases with the proceeding process of aging, Z 4 (periterritorial zone) and Z 5 (interterritorial zone) appear in the cartilage centre. In adolescence only Z 5 can be found; it is slightly hyaluronidase-sensitive and stains even at high MgC12-concentrations. In adult and old cartilage a weakly basophilic zone 4 appears. The comparison of fixed and unfixed tissues renders the distinction between the zones feasible as the hyalurinodase resistance is increased in fixed tissue and, on the other hand, the structures appear less outlined in unfixed tissue. As far as the distribution of acidic glycosaminoglycans (GAG) is concerned the territories and interterritories are not clearly defined units, for part of the zones mentioned above can be arranged circumcellularly or, in addition, interstitially depending on the various cartilage regions and on the different periods of life. We assume that the pericellular as well as the inner and outer territorial zones belong to the cell itself and that their step by step appearance is due to a process of development whereas the periterritorial and interterritorial zones result from cell degeneration caused by aging, and expand, mainly, without cellular control.

Adolescent↗
PubMedDate not supplied

The fate of cartilage grafts for ossicular reconstruction in tympanoplasty.

Summary--Six autograft tragal cartilages and two preserved homograft nasal septal cartilages removed from revision tympanoplasty were examined with histologic and histochemical stains. The implanted cartilage remained in the middle ear from six months to eighteen months without significant inflammatory reaction or evidence of resorption. It appears that the implanted cartilages removed from tympanoplasty have been well tolerated in the middle ear space.

Adolescent↗
PubMed1976

Lubrication and cartilage.

Mechanisms of lubrication of human synovial joints have been analysed in terms of the operating conditions of the joint, the synovial fluid and articular cartilage. In the hip and knee during a walking cycle the load may rise up to four times body weight. In the knee on dropping one metre the load may go up to 25 time body weight. The elastic modulus of cartilage is similar to that of the synthetic rubber of a car tyre. The cartilage surface is rough and in elderly specimens the centre line average is 2-75 mum. The friction force generated in reciprocating tests shows that both cartilage and synovial fluid are important in lubrication. The viscosity-shear rate relationships of normal synovial fluid show that it is non-Newtonian. Osteoarthrosic fluid is less so and rheumatoid fluid is more nearly Newtonian. Experiments with hip joints in a pendulum machine show that fluid film lubrication obtains at some phases of joint action. Boundary lubrication prevails under certain conditions and has been examined with a reciprocating friction machine. Digestion of hyaluronate does not alter the boundary lubrication, but trypsin digestion does. Surface active substances (lauryl sulphate and cetyl 3-ammonium bromide) give a lubricating ability similar to that of synovial fluid. The effectiveness of the two substances varies with pH.

Cartilage, Articular↗
PubMed1978

Physicochemical properties of cartilage proteoglycans extracted by lanthanum chloride.

Bovine nasal cartilage was extracted with 0.5 M LaCl3 and the extract then diluted with nine volumes of water. The resulting precipitated (PLaCl3) contained the proteoglycan subunits, together with minor protein components, but was essentially free from hyaluronic acid. The properties of PLaCl3 were investigated by chemical analysis, electrophoresis, viscometry and analytical ultracentrifugation, and the results compared with those for proteoglycan obtained by caesium chloride density gradient centrifugation of 2 M CaCl2 cartilage extracts. Proteoglycan subunits (A1D1) prepared from PLaCl3 showed identical properties to those obtained from other high ionic strength cartilage extracts.

Animals↗
PubMed1978

Degradation of proteoglycan in articular cartilage.

Adult rabbit articular cartilage was labelled in vivo over 48 h with [35S]sulphate and was then incubated in organ culture at pH 7.2. Approx. 65% of the tissue content of [35S]proteoglycan was released into the culture medium during the first 48 h of incubation. The average molecular size of the released proteoglycans, as assessed by fractionation on Sepharose 2B/CL and 4B/Cl, was only slightly smaller than that of the proteoglycans extracted from non-cultured cartilage with 4 M guanidine HCl. The percentage of released proteoglycans and extracted proteoglycans which formed aggregates with hyaluronic acid was approx. 25% and 75%, respectively. The results indicate that proteoglycan degradation in adult articular cartilage is initiated by a limited proteolysis of subunit core protein, with the production of non-aggregating species which diffuse readily from the tissue.

Animals↗
PubMed1979

Alterations in cartilage metabolism by neurostimulant drugs.

Suppression of growth without significant alterations in hormonal patterns has been demonstrated for the neurostimulant drug pemoline. Comparison of the in vitro effect of pemoline, methylphenidate, and methamphetamine on somatomedin-stimulated sulfate uptake by cartilage showed all three drugs to be inhibitory. Sulfate uptake by cartilage can be directly related to growth and glycosaminoglycan biosynthesis. Assay of two of the enzymes involved in the glycosaminoglycan biosynthetic pathway showed that methamphetamine and methylphenidate caused a marked depression of xylosyl- and galactosyltransferase enzyme activity. These data suggest an interference with cartilage metabolism as one possible mechanism for the growth retardation observed in children on neurostimulant drug therapy.

Animals↗
PubMed1978

Isolation of proteoglycans from human articular cartilage.

Proteoglycans were extracted from normal human articular cartilage of various ages with 4M-guanidinium chloride and were purified and characterized by using preformed linear CsCl density gradients. With advancing age, there was a decrease in high-density proteoglycans of low protein/uronic acid weight ratio and an increase in the proportion of lower-density proteoglycans, richer in keratan sulphate and protein. Proteoglycans of each age were also shown to disaggregate in 4M-guanidinium chloride and at low pH and to reaggregate in the presence of hyaluronic acid and/or low-density fractions. Osteoarthrotic-cartilage extracts had an increased content of higher-density proteoglycans compared with normal cartilage of the same age, and results also suggested that these were not mechanical or enzymic degradation products, but were possibly proteoglycans of an immature nature.

Adolescent↗