Showing papers on "Cartilage published in 1973"

Experimentally induced degenerative joint lesions following partial meniscectomy in the rabbit.

Abstract: Degenerative lesions characterized by osteochondrophyte spur formation and cartilage degeneration were induced by partial meniscectomy in the rabbit knee. Cartilage degenerative lesions included ulceration, fissure and cyst formation, and diminished concentration of matrix proteinpolysaccharide. Proliferation of chondrocytes represented efforts at repair. Osteophytes increased in size with time. Changes resembled certain components of degenerative joint disease. The partial meniscectorny animal may be useful in studies of osteoarthritis pathogenesis, pathology and treatment.

Multiple aggregation factors in cartilage proteoglycan.

Abstract: Proteoglycan as isolated from bovine nasal septa is a partially aggregated complex containing linking factors. Two essential factors can be separated from proteoglycan subunits and resolved in a CsCl density gradient. Chondroitinase digestion of the purified proteoglycan subunits does not interfere with their aggregation when the linking factors are added.

The resistance of certain tissues to invasion: penetrability of explanted tissues by vascularized mesenchyme.

Abstract: If puppy tissues are explanted onto the chick chorioallantoic membrane, those tissues which normally have a blood supply are rapidly invaded by vascularized mesenchyme of host origin. Hyaline cartilage, a tissue virtually devoid of blood vessels, is impenetrable by proliferating mesenchyme of the host, while calcified cartilage, which normally is vascularized, is penetrable. The stroma of the cornea, another normally avascular tissue, is readily penetrable, but Descemet's membrane forms a barrier to invasion by host tissues. The experimental system used permits the design of experiments in which the study of factors responsible for the resistance of tissues such as cartilage to invasion can be undertaken.

The uptake of [45Ca]calcium ions by matrix vesicles isolated from calcifying cartilage (Short Communication)

Abstract: Extracellular membranous matrix vesicles, which contain various phosphatases and appear to initiate hydroxyapatite formation in growth cartilage, were isolated and incubated with 45Ca2+ and shown to form mineral in the presence of ATP. There is enhanced calcification in the presence of serum and under alkaline conditions.

Cartilage of the patella. Topographical variation of glycosaminoglycan content in normal and fibrillated tissue.

Abstract: The variation in the glycosaminoglycan content was studied at different sites of the patella, both where the cartilage was intact and where it showed varying degrees of fibrillation. It was found that when the cartilage surface was intact the glycosaminoglycan content was the same at the different sites of the patella. Local fibrillation always gave rise to a local lowering of fixed charge density, the magnitude of the latter correlating well with the visual assessment of the severity of the lesion. Even in the presence of severe lesions, if there was a site left on the patella where the cartilage was visually normal, its fixed charge density was also at a normal level. Thus, the depletion of glycosaminoglycans is a local phenomenon, limited to the area of fibrillation. The glycosaminoglycan content of normal cartilage is lower in the knee joint than in the hip. This fact, together with the existence of high pressure during load bearing, may be responsible for the greater frequency of destructive lesions affecting the cartilage of the patella compared with that of the hip.

Biochemistry of articular cartilage. Nature of proteoglycans and collagen of articular cartilage and their role in ageing and in osteoarthrosis.

Abstract: The cartilage which covers the articular surfaces of bones of vertebrate animals has two main functions: the limitation of stress applied to the bone extremities and the provision of the smooth surfaces necessary for the joint to function as an efficient bearing (Kempson, Spivey, Freeman, and Swanson, 1969). To meet these functional demands the cartilage exhibits a combination of physical properties which are unique to the tissue. Boundary effects, resulting from the interaction of the cartilage surface with synovial fluid, provide thejoint with a bearing surface having a very low coefficient of friction. Articulation of a joint produces compressive stresses which arise from both muscle pull and gravity. In the absence of articular cartilage these stresses would be transmitted directly to the bones and would possibly fracture them. The viscoelastic nature of articular cartilage enables it to absorb the energy of these mechanical stresses. When an external stress is applied to the cartilage, the tissue undergoes a slowly progressive deformation. When the external stress is removed the cartilage can restore its original shape. The principal components of articular cartilage are the insoluble fibrous protein collagen and the soluble proteoglycans. A complex organization of collagen, proteoglycans, the fluid environment, and as yet uncharacterized components, endows the tissue with the capacity for reversible deformability, a property essential for its physiological function. The biochemist is primarily interested in the chemical composition of the tissue, the elucidation of the structure and organization of the constituent macromolecules, the nature of the synthetic and degradative systems in the tissue, and the influence of age and pathological state on these phenomena. Articular cartilage, as a tissue, has presented considerable difficulties to biochemical investigation. The tissue displays a complex morphology, as yet incompletely understood, and is very resistant to solubili-

Biosynthesis of Cartilage Procollagen

Abstract: Cells were isolated by controlled enzymic digestion of sternal cartilages from chick embryos and the cells were studied immediately after isolation for up to 4 h in vitro The cells isolated under the conditions employed had a high degree of viability, they remained in suspension for 2 to 4 h in vitro and during this time they synthesized and secreted collagen in the precursor form which has been called “transport form” or “procollagen” The cells also incorporated [35S]sulfate into macromolecules which were secreted into the medium Continuous labeling of the cartilage cells demonstrated a lag of about 33 min between the time at which the rate of synthesis of collagen [14C]hydroxyproline became linear and the time at which the secretion of collagen [14C]hydroxyproline into the medium became linear Gel filtration and polyacrylamide-gel electrophoresis in sodium dodecylsulfate indicated that all the secreted collagen was in the precursor form The procollagen differed from the procollagen previously isolated from bone, tendon and cultured fibroblasts in that it apparently consisted of a single type of polypeptide chain Isotopic studies suggested that the NH2-terminal extension on the cartilage procollagen contained cystine and tryptophan and appeared therefore to be similar in this respect to that of other procollagens

Release of cartilage mucopolysaccharide-degrading neutral protease from human leukocytes

Abstract: The granule fraction of human leukocytes contains neutral protease capable of degrading the noncollagenous protein mucopolysaccharide matrix of cartilage at neutral pH in physiological salt solution. Cartilage degradation was monitored by quantitating the release of 35S from labeled rabbit ear cartilage. Degradation of cartilage matrix occurs when intact viable human leukocytes are incubated with cartilage opsonized with aggregated human gamma globulin (AHGG). During a similar 4 h incubation period cells did not degrade uncoated cartilage or cartilage coated with nonaggregated gamma globulin. Cells remain viable during the enzyme release process as evidenced by the absence of a cytoplasmic enzyme marker (lactic dehydrogenase) in the supernatant and dye exclusion studies. The release of 35S from labeled cartilage by human leukocytes in the presence of cartilage coated with AHGG (nonphagocytic enzyme release) was compared with the cartilage degrading activity of the supernatant from the same number of cells preincubated with a suspension of AHGG (phagocytic enzyme release). Nonphagocytic enzyme release by 5 x 106 cells provoked two to four times more 35S and β-glucuronidase (β-G) release from cartilage than phagocytic enzyme release conditions. β-glucuronidase was used as an indicator of the release of lysosomal granule enzymes. By the use of selected pharmacological agents it was possible to dissociate the enzyme release process from intrinsic enzyme (neutral protease) activity. Neutral protease and β-G release by human cells in the presence of AHGG-coated cartilage was inhibited by 10–5M colchicine, whereas the protease activity, but not the release process, was inhibited by 10–6M gold thiomalate and 10% human serum. It is suggested that the release of a cartilage degrading neutral protease by viable human cells when exposed to AHGG might be a relevant model for the study of cartilage destruction as it occurs in rheumatoid arthritis.

Immunopathologic Studies in Relapsing Polychondritis

Abstract: Serial studies have been performed on three patients with relapsing polychondritis in an attempt to define a potential immunopathologic role for degradation constituents of cartilage in the causation and/or perpetuation of the inflammation observed. Crude proteoglycan preparations derived by disruptive and differential centrifugation techniques from human costal cartilage, intact chondrocytes grown as monolayers, their homogenates and products of synthesis provided antigenic material for investigation. Circulating antibody to such antigens could not be detected by immunodiffusion, hemagglutination, immunofluorescence or complement mediated chondrocyte cytotoxicity as assessed by (51)Cr release. Similarly, radiolabeled incorporation studies attempting to detect de novo synthesis of such antibody by circulating peripheral blood lymphocytes as assessed by radioimmunodiffusion, immune absorption to neuraminidase treated and untreated chondrocytes and immune coprecipitation were negative. Delayed hypersensitivity to cartilage constituents was studied by peripheral lymphocyte transformation employing [(3)H]thymidine incorporation and the release of macrophage aggregation factor. Positive results were obtained which correlated with periods of overt disease activity. Similar results were observed in patients with classical rheumatoid arthritis manifesting destructive articular changes. This study suggests that cartilage antigenic components may facilitate perpetuation of cartilage inflammation by cellular immune mechanisms.

The action of cathepsin D in human articular cartilage on proteoglycans.

Abstract: In recent years the lysosomal cathepsins have been implicated as important agents in the physiological degradation of various cartilages. In the present study, the nature of cathepsin present in human articular cartilage was investigated by microtechniques and a possible role for cathepsins in the cartilage degradation observed in osteoarthritis was sought. The results of this study indicated that the hemoglobin and proteoglycan-digesting activity in the human cartilage observed is predominantly that of a cathepsin D-type enzyme. This cathepsin D-type enzyme activity was present in two to three times greater amounts in yellowish or ulcerated articular cartilage from patients with primary osteoarthritis than in control “normal” human cartilages. The human cathepsin D-type enzyme, as well as a highly purified cathepsin D from bovine uterus degraded proteoglycan subunit (PGS) maximally at pH 5. Both enzyme preparations were inactive on hemoglobin at pH 6-8, but degraded PGS considerably at neutral pH. The activity of the human cathepsin extract was not affected by reagents which inhibit or activate cathepsins A and B. Neutral proteases which are active on hemoglobin or are inhibited by diisopropylfluorophosphate (DFP) were not detected in these preparations, but contamination by another type of neutral protease cannot be excluded. Chloroquine inhibited the degradation of PGS at neutral pH by the human cartilage enzyme extract.

Chondrocyte multiplication in osteoarthritic articular cartilage

Abstract: 1. Twelve trephine specimens of articular cartilage and subchondral bone taken from six fresh osteoarthritic femoral heads were incubated in a medium containing tritiated thymidine, and autoradiographs were prepared from serial sections five microns thick. 2. Scattered labelling of chondrocytes in sections from four of the six femoral heads was demonstrated. No more than four labelled cells were seen in any one section. About half were found in typical chondrocyte clusters. 3. The implications of this evidence of chondrocyte multiplication with regard to the repair of damaged articular cartilage are discussed.

Fatigue of articular cartilage.

Abstract: IT has been suggested1 that fibrillation, the earliest change in osteoarthritic cartilage visible to the naked eye, may be the result of fatigue failure. Abnormally high stresses in the superficial layer of cartilage could be produced by unusually high applied loads, incongruity of the joint surface, or softening of the cartilage by mucopolysaccharide loss. Repeated cyclic loading could then lead to fatigue failure in the surface layer. To test this hypothesis postmortem human articular cartilage was subjected to repetitive compressive loads.

Somite chondrogenesis. A structural analysis.

Abstract: Light and electron microscopy are used in this study to compare chondrogenesis in cultured somites with vertebral chondrogenesis These studies have also characterized some of the effects of inducer tissues (notochord and spinal cord), and different nutrient media, on chondrogenesis in cultured somites Somites from stage 17 (54–60 h) chick embryos were cultured, with or without inducer tissues, and were fed nutrient medium containing either horse serum (HS) and embryo extract (EE), or fetal calf serum (FCS) and F12X Amino acid analyses were also utilized to determine the collagen content of vertebral body cartilage in which the fibrils are homogeneously thin (ca. 150 A) and unbanded. These analyses provide strong evidence that the thin unbanded fibrils in embryonic cartilage matrix are collagen. These thin unbanded collagen fibrils, and prominent 200–800 A protein polysaccharide granules, constitute the structured matrix components of both developing vertebral cartilage and the cartilage formed in cultured somites Similar matrix components accumulate around the inducer tissues notochord and spinal cord. These matrix components are structurally distinct from those in embryonic fibrous tissue The synthesis of matrix by the inducer tissues is associated with the inductive interaction of these tissues with somitic mesenchyme. Due to the deleterious effects of tissue isolation and culture procedures many cells die in somitic mesenchyme during the first 24 h in culture. In spite of this cell death, chondrogenic areas are recognized after 12 h in induced cultures, and through the first 2 days in all cultures there are larger accumulations of structured matrix than are present in equivalently aged somitic mesenchyme in vivo. Surviving chondrogenic areas develop into nodules of hyaline cartilage in all induced cultures, and in most non-induced cultures fed medium containing FCS and F12X There is more cell death, less matrix accumulation, and less cartilage formed in cultures fed medium containing HS and EE. The inducer tissues, as well as nutrient medium containing FCS and F12X, facilitate cell survival, the synthesis and accumulation of cartilage matrix, and the formation of cartilage nodules in cultured somites.

Early submucous resection of nasal septal cartilage. A pilot study in canine pups.

Abstract: An experimental design was executed to determine the effects on snout and midfacial growth of performing submucous resections of large pieces of septal cartilage on 6-week-old canine pups. Some pieces of intact fresh cartilage were autografted. Gross findings failed to show any perceptible growth disturbances, and the autografts continued to grow more or less proportionately to the rest of the septum.

The composition of cartilage proteoglycans. An investigation using high-and low-ionic-strength extraction procedures

Abstract: 1. A proteoglycan fraction (the proteoglycan subunit fraction) was prepared from extracts, with 0.15m-KCl (low-ionic-strength) and 0.5m-LaCl3, 2.0m-CaCl2 and 4.0m-guanidinium chloride (high-ionic-strength), of bovine nasal cartilage by equilibrium-density-gradient centrifugation, essentially as described by Hascall & Sajdera (1969). 2. The use of different centrifugation times showed that near-equilibrium conditions were reached by 48h for the fractions prepared from the high-ionic-strength extracts. The fraction isolated from the low-ionic-strength extract required a longer centrifugation time to reach equilibrium conditions. 3. The composition of the proteoglycan fractions from the various extracts was compared by analyses of their carbohydrate and amino acid contents. Difference indices were calculated from the amino acid analysis to compare the degree of compositional relationship between the protein components of the proteoglycans. 4. Small compositional differences were found between the proteoglycans isolated from the various high-ionic-strength extracts. The protein content of the fractions from the CaCl2 extract and the guanidinium chloride extract showed the greatest difference in this respect, although their amino acid analysis was similar. 5. The proteoglycan fraction isolated from the low-ionic-strength extract shows marked differences in composition from the fractions isolated from the high-ionic-strength extracts. Its protein and glucosamine contents were lower whereas its hexuronic acid and galactosamine contents were higher than those of the latter. It also exhibits major differences in its amino acid composition. The glucosamine:galactosamine ratio of the fraction from the low-ionic-strength extract indicates that it may be an almost exclusively chondroitin sulphate–proteoglycan. Its analysis correlates closely with that of a low-molecular-weight proteoglycan isolated from pig laryngeal cartilage by Tsiganos & Muir (1969). 6. The proteoglycan fractions from both the low- and high-ionic-strength extracts migrate as a single band in zone electrophoresis carried out in a sucrose-density gradient at both pH3.0 and pH7.0, although each showed evidence of band widening during the electrophoresis. All the proteoglycan fractions migrated with the same electrophoretic mobility at pH3.0, irrespective of the differences in composition between them. 7. The differences between the proteoglycans from the low- and high-ionic-strength extracts are discussed and the view is advanced that they may be due to association between predominantly chondroitin sulphate–proteoglycans and a keratan sulphate-enriched proteoglycan species.

Acid hydrolase activity in osteoarthritic and normal human cartilage.

Abstract: As an index of lysosomal enzyme activity in cartilage from twenty osteoarthritic and twelve normal joints, the acid phosphatase activity was determined and correlated with the histochemical-histological grading of the severity of the arthritis. The activity was increased four to five times normal in the arthritic cartilage with a positive correlation between activity and severity of the disease and was also increased in the cartilage of the osteophytes, possibly due to immaturity. This finding supports current concepts of the role of lysosomal enzymes in osteoarthritis.

Extracellular localization of cathepsin D in ossifying cartilage.

Abstract: Extracellular cathepsin D derived mainly from osteoblasts has been demonstrated immunohistochemically in ossifying cartilage of cultured embryonic chick limb bones. The relevance of this observation to the mechanism of ossification is discussed.

Immunopathologic significance of cartilage antigenic components in rheumatoid arthritis.

Abstract: Patients with rheumatoid arthritis have been studied in an attempt to detect immune responses to cartilage antigens that might function in the causation and/or perpetuation of joint inflammation. Cartilagenous antigenic determinants could be consistently demonstrated in synovial fluid and its phagocytic cellular components. Antibody to such constituents could not be detected in serum, synovial fluid or immunoglobulin eluted from or synthesized de novo by rheumatoid synovium. However, delayed hypersensitivity to cartilage antigens correlating with clinical evidence of inflammatory cartilagenous degradation could be identified.

Collagen-Proteoglycan Relationships in Epiphyseal Cartilage

Abstract: Columnar and hypertrophic zones of calf scapular cartilage were studied before and after extraction with 3 M guanidinium chloride (GuCl) and digestion with enzymes which degrade various components of the extracellular matrix. Morphologic and chemical analysis suggests that there are at least two anatomic pools of proteoglycan in this tissue. One, which resides between collagen fibrils, is extractable with GuCl. Another appears attached to collagen by strong bonds and is apparently not extractable with GuCl. This type of collagen-proteoglycan relationship is possibly restricted to epiphyseal cartilage. The morphology of the lacuna is different in the columnar and hypertrophic zones. Proteoglycans in the distal hypertrophic zone are less resistant to GuCl extraction.

Electron microscopic visualization of proteoglycans and collagen in bovine costal cartilage.

Abstract: Removal of the soluble proteoglycans from slices of bovine costal cartilage by extraction in 4 M guanidinium hydrochloride permitted the visualization of abundant amounts of dispersed and disaggregated collagen in the matrix. Proteoglycans which are resistant to extraction are seen as small granules which are concentrated in the perilacunar regions. Large proteoglycan granules appear to originate in the chondrocyte. As they come to occupy positions in the matrix distant from the chondrocyte, the granules become smaller. A non-granular, “amorphous” component masks the collagen fibers so that they cannot be readily seen in the intact cartilage.

Resorption of calcified cartilage as seen in Meckel's cartilage of rats

Abstract: In rats, a portion of Meckel's cartilage — that lying within the mandible but proximal to the rostral convergence of the bars — gives rise to no definitive structures. It offers especially favorable opportunity to study cartilage resorption. By the eighteenth fetal day it is established as a hyaline cartilage bar, and a thin perichondral bone shell starts to form on its lateral aspect, completing encirclement in the next two days. On day 19 cartilage within this bone shows chondrocyte hypertrophy, lacunar enlargement, and matrix calcification. Osteoclasts open a fenestra laterally in the bone and commence removal of calcified cartilage matrix. The erosion front expands rapidly, moving medially (preceded by cartilage hypertrophy and calcification) and extending proximally and distally along the segment. Chondroclasts (multinucleated cells identical with osteoclasts) dominate the erosion front. Capillaries and various mononucleated cells follow. Bone formation is much delayed except in the most rostral extremity, so that, contrary to the situation in endochondral osteogenesis, one is examining calcified cartilage resorption in uncomplicated form. This resorption, including the perichondral bone shell, is virtually complete by day 21, and intramembranous bony reorganization of the site is in progress at birth. Several features of chondroclasts, including some in dispute or not easily seen in vivo, are well displayed. These include ameboid form with pseudopodial extensions (sometimes filamentous), and fusion of some released chondrocytes with entering chondroclasts. Osteo/chondroclasts are often found in contact with perichondral bone at one extremity and calcified cartilage elsewhere on the same cell. There is evidence that matrix calcification is prerequisite to the chondroclastic activity.