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C A McDevitt

Publications and source records attributed to C A McDevitt.

36 records · Page 2Linked to original sources
PubMed1988

Thrombospondin is present in articular cartilage and is synthesized by articular chondrocytes.

Thrombospondin, a multifunctional adhesive glycoprotein originally identified in platelets, was isolated and identified from an extract of ovine articular cartilage. Immunoreactive material from a cartilage extract comigrated on gel electrophoresis with purified human platelet thrombospondin. When articular chondrocytes were cultured in the presence of 35S-methionine, metabolically labeled thrombospondin was immunoprecipitated from the culture medium and cell layer extract. These results demonstrate that thrombospondin is present in articular cartilage and is synthesized by articular chondrocytes.

Animals↗
PubMed1988

Proteoglycans of the human intervertebral disc. Electrophoretic heterogeneity of the aggregating proteoglycans of the nucleus pulposus.

Nuclei pulposi were dissected from lumbar discs of radiologically normal human spines of cadavers aged 17, 20 and 21 years. Proteoglycans were extracted with 4 M guanidine hydrochloride (dissociative conditions) with proteinase inhibitors and isolated as A1 fractions by associative density-gradient centrifugation. Aggregating and non-aggregating proteoglycans were separated by Sepharose 2B chromatography. Both aggregating and non-aggregating proteoglycans contained a keratan sulphate-rich region as isolated by chondroitinase/trypsin/chymotrypsin digestion and Sepharose CL-6B chromatography. Agarose/acrylamide-gel electrophoresis of individual fractions of a Bio-Gel A-50m dissociative-column separation of the aggregating proteoglycans revealed two, well-separated bands: S and F, the slower and faster migrating bands respectively. The non-aggregating proteoglycan fractions were eluted under associative conditions (0.5 M-sodium acetate, pH 6.8) and migrated as a single band in the electrophoretic system. The gel-electrophoretic heterogeneity of the aggregating proteoglycans was still evident after hydroxylamine fragmentation and removal of the hyaluronate-binding portion of the molecule. Dissociative density-gradient centrifugation of the aggregating proteoglycans partially separated the Band-S proteoglycans from the Band-F population. Subsequent dissociative chromatography of the high-buoyant-density Band F proteoglycans permitted discrimination of this band into two gel-electrophoresis-distinguishable populations (Bands F-1 and F-2). Enzyme-linked immunosorbent assays with a monoclonal antibody that recognized keratan sulphate demonstrated that the D1 fraction containing the Band F-1 proteoglycans was enriched in keratan sulphate compared with the total aggregating or non-aggregating pool of proteoglycans. The proteoglycans of young adult nucleus pulposus could then be ascribed to one of four structurally and/or electrophoretically distinct populations: (1) the non-aggregating population, which comprised about 70% of the total extractable proteoglycans; (2) the aggregating pool, comprising: (a) Band F-1 proteoglycans, which had a relatively large hydrodynamic size, uronate/protein weight ratio, were enriched in keratan sulphate and had a high buoyant density; (b) Band S proteoglycans, which migrated slower in agarose/acrylamide gels, had a smaller hydrodynamic size, lower buoyant density and a lower uronate/protein ratio than the Band F-1 population; (c) Band F-2 proteoglycans, which were lower in buoyant density, smaller in hydrodynamic size and slightly faster in electrophoretic mobility than the Band F-1 proteoglycans.

Adolescent↗
PubMed1988

The effect of cryopreservation on canine menisci: a biochemical, morphologic, and biomechanical evaluation.

This study evaluated the effect of cryopreservation on the structural organization, biosynthetic activity, and material properties of canine menisci. The menisci were cryopreserved by incubating them in a 4% solution of dimethyl sulfoxide (DMSO) in physiologic media and freezing them to -100 degrees C using a controlled rate freezing system. The menisci were then stored for varying periods of time from zero to 12 weeks in liquid nitrogen (-196 degrees C). Following rapid thawing, changes in the histological appearance and biosynthetic activity of the menisci were evaluated as functions of storage time. In addition, the effects of the cryopreservation process on the tensile strength and modulus of the meniscal tissue were assessed. Although cryopreservation and short-term storage did not appear to affect the morphological appearance or biomechanical character of the menisci, biosynthetic activity, as determined by Na2S35SO4 incorporation, was diminished to less than 50% of normal control values immediately following cryopreservation and thawing. Autoradiographic examination of these tissues revealed that only approximately 10% of the meniscal cells were metabolically active, however, indicating that a marked increase in the metabolic activity of individual cells occurs following the freeze-thaw cycle. Total metabolic activity continued to decline with storage time.

Animals↗
PubMed1988

Stimulation of matrix formation in rabbit chondrocyte cultures by ascorbate. 1. Effect of ascorbate analogs and beta-aminopropionitrile.

The most consistent effects of 0.2 mM L-ascorbate on monolayer cultures of rabbit articular chondrocytes were a diversion of incorporated radiosulfate into a pericellular matrix and enhancement of cell proliferation. Only with certain batches of fetal bovine serum (FBS) was there a cell-for-cell increase of proteoglycan synthesis. These actions increased as the cell inoculum rose from 0.5 to 2 x 10(5) cells/T25 flask. Maximal effects of ascorbate and D-isoascorbate were found over a range of 0.05-0.2 mM. L-Dehydroascorbic acid was less effective than either, and no stimulatory action was exerted by L-cysteine, glutathione, dithiothreitol, methylene blue, or phenazine methosulfate. Ascorbate increased the hypro:pro ratio of newly synthesized proteins. beta-Aminopropionitrile (1 mM) reduced the proportion of [3H]hydroxyproline and [35S]O4-proteoglycans in the ascorbate-supplemented matrix 31 and 7%, respectively. In corresponding electronmicrographs, the number of pericellular filaments was reduced. We conclude: (a) Ascorbate has a general anabolic effect on chondrocytes in culture and enhances matrix assembly through mechanisms other than its redox function; (b) deposition of proteoglycans in the matrix is not simply the result of mechanical entrapment by allysine- or hydroxyallysine-derived cross-linking of collagen; and (c) contradictory reports on the subject result from variations in the serum employed, inoculum density, and concentration of ascorbate.

Aminopropionitrile↗
PubMed1988

Stimulation of matrix formation in rabbit chondrocyte cultures by ascorbate. 2. Characterization of proteoglycans.

The effect of ascorbate on the proteoglycans synthesized by rabbit articular chondrocytes was studied in first- and third-passage cultures for 12 and 26 days total duration, respectively. L-Ascorbate (0.2 mM) was added daily to half of the flasks after attachment of the cells. The cultures were labeled with Na2[35S]O4 or [14C]-glucosamine and [3H]-proline. Proteoglycans were isolated from the media and pericellular matrices by dissociative extraction and associative density gradient centrifugation. There was a large decline in the amount of proteoglycan synthesized between early and late cultures. Ascorbate increased the DNA content, amount of radiosulfate incorporated into glycosaminoglycans per microgram of DNA, and the proportion of labeled proteoglycan in the pericellular fraction of both short- and long-term cultures. The proteoglycans of the media and matrices of all cultures, with and without ascorbate, eluted as aggregates under associative column chromatographic conditions. The proteoglycans of 26-day cultures exhibited a higher degree of polydispersity in size than those of the short-term culture and contained small amounts of keratan (2-5%) and dermatan sulfate (4-8%) as assessed by keratanase and chondroitinase digestions, respectively. The effect of ascorbate, therefore, was to increase the amount of proteoglycan formed and to direct it into matrix deposition rather than to alter its quality.

Animals↗
PubMed1986

Protein and lysozyme content of adult human nucleus pulposus.

A radiologically normal human nucleus pulposus was extracted with 4 M guanidinium chloride and the non-collagenous proteins separated from the proteoglycans by dissociative density gradient centrifugation. Lysozyme was identified as a matrix constituent of the normal, mature human nucleus pulposus.

Adult↗
PubMed1986

Isolation and characterization of high-buoyant-density proteoglycans from semilunar menisci.

Proteoglycans were extracted from adult canine menisci in high yield and were purified, and the major species were characterized biochemically. Most proteoglycans in menisci were isolated in the high-buoyant-density fraction. By agarose-acrylamide composite gel electrophoresis, two proteoglycans were seen in this fraction. Although they were smaller than those from porcine laryngeal hyaline cartilage and had shorter chondroitin sulphate and keratan sulphate chains and a lower carbohydrate-to-protein ratio, they were functionally similar to those in hyaline cartilage in their specific interaction with hyaluronate.

Animals↗
PubMed1985

Changes in the chondroitin sulfate-rich region of articular cartilage proteoglycans in experimental osteoarthritis.

The chondroitin sulfate-rich region was cleaved from cartilage proteoglycans of experimental osteoarthritic canine joints to establish whether changes in this region of the molecule contribute to the well-documented increase in the chondroitin sulfate to keratan sulfate ratio in osteoarthritis. Experimental osteoarthritis was induced in eight dogs by severance of the right anterior cruciate ligament, the left joint serving as a control. Proteoglycans were extracted from the femoral cartilage of both joints, isolated as A1 fractions by associative density gradient centrifugation and cleaved with hydroxylamine. The chondroitin sulfate-rich region was isolated by either gel chromatography or dissociative density gradient centrifugation. The chondroitin sulfate-rich region from the proteoglycans of the experimental osteoarthritic joints was slightly larger in hydrodynamic size and had both a higher uronate/protein weight ratio and galactosamine/glucosamine molar ratio than the corresponding control. We conclude that the chondroitin sulfate-rich region of proteoglycans in articular cartilage of experimental osteoarthritic joints is larger and has more chondroitin sulfate than that of proteoglycans of normal cartilage.

Amino Sugars↗
PubMed1985

The pathobiology of human neuromas: an electron microscopic and biochemical study.

The formation of neuroma scar after trauma or neurorrhaphy is believed to be mediated by the response of collagen forming fibroblasts. In this study of twenty human neuromas, myofibroblasts were identified as a component of the scar. These cells occurred singly or as aggregates. There was a qualitative increase of myofibroblasts during the period from two to six months post-injury. From six months to one and one-half years post-injury, numbers and aggregations of myofibroblasts diminished, concurrent with collagen proliferation. Ultrastructural alcian blue staining and biochemical analyses revealed a glucosamine--glycosaminoglycan matrix within neuromas when compared to control nerves. Myofibroblasts appear to play a part in the pathobiology of human neuromas.

Adolescent↗
PubMed1983

Xenografts of articular chondrocytes in the nude mouse.

Subcutaneous transplantation of articular chondrocytes isolated enzymatically from immature rabbits and dogs into athymic (nu/nu) mice resulted in the formation of hyaline cartilaginous nodules. Graft rejection was seen when the cells were injected into heterozygous (nu/+) mice. Radiosulfate-labeled proteoglycan extracted from the xenografts had a high buoyant density and was digested by chondroitinase ABC. A monomeric preparation of proteoglycan (A1-D1) contained a small quantity of aggregate as assessed by gel chromatography and gel electrophoresis. Almost no incorporation of 3H-thymidine was found by autoradiography. The matrix did not become calcified over the course of 42 days. The nude mouse system lends itself to testing a variety of problems in the biology of cartilage. These include the redifferentiation of chondrocytes following dedifferentiation in vitro. Species differences were found in this regard. The nodules formed by rabbit articular chondrocytes, grown in monolayer culture for up to 14 days, had a hyaline chondroid character. Dog chondrocytes that had "dedifferentiated" during 14 days of culture prior to transplantation, formed a graft that had a sparse fibrous rather than hyaline matrix.

Animals↗
PubMed1982

Effect of purified growth factors on rabbit articular chondrocytes in monolayer culture. II. Sulfated proteoglycan synthesis.

The effect of 3 purified peptide growth factors--platelet-derived growth factor (PDGF), epidermal growth factor (EGF), pituitary fibroblast growth factor (FGF)--heat-inactivated fetal bovine serum (FBS), insulin, and 0.2 mM ascorbate on synthesis of sulfated proteoglycan by rabbit articular chondrocytes was studied in monolayer culture. Growth of the cells increased linearly as the concentration of heat-inactivated FBS rose from 0 to 30%. Glycosaminoglycan (GAG) synthesis (35SO4/micrograms DNA) was enhanced as the concentration of heat-inactivated FBS went from 0 to 5%. At higher levels of serum, radiosulfate incorporation declined progressively. Two modes of study of the test factors were used: 1) the dose of the factor was increased while the serum concentration was fixed at a low basal level (1% heat-inactivated FBS); 2) the dose of the test factor was kept constant but the level of heat-inactivated FBS varied from 0 to 10%. There was an inverse relationship between GAG and DNA synthesis when proliferation of cells was increased by EGF and platelet lysate. PDGF (1 U/ml) stimulated radiosulfate incorporation as well as DNA formation in the serum-free medium; the values for GAG synthesis did not increase as the serum concentration increased, but the cell mass did. The action of FGF was intermediate between that of EGF and PDGF: with 50 ng FGF/ml, increasing concentrations of serum caused a large progressive reduction of radiosulfate incorporation as growth was stimulated. In basal medium, however, FGF caused mild enhancement of GAG synthesis. Insulin increased aggregatable proteoglycan production far out of proportion to its growth-promoting activity in the presence of 1% heat-inactivated FBS. The response was effaced when higher concentrations of serum were employed. Ascorbate had a unique anabolic effect, increasing both cell growth and proteoglycan synthesis that is not suppressed by higher concentrations of serum. The content of serum and its several peptide and hormonal components thus have divergent effects on growth and proteoglycan synthesis in cell culture. This phenomenon must be taken into account in studying biochemical processes and pharmacologic reactions of articular chondrocytes in vitro.

Animals↗
PubMed1980

Biosynthesis of collagen and other matrix proteins by articular cartilage in experimental osteoarthrosis.

Osteoarthrosis was induced in one knee joint of dogs by an established surgical procedure. Changes in the articular cartilage in the biosynthesis of collagen and other proteins were sought by radiochemical labelling in vivo, with the following findings. (1) Collagen synthesis was stimulated in all cartilage surfaces of the experimental joints at 2, 8 and 24 weeks after surgery. Systemic labelling with [3H]proline showed that over 10 times more collagen was being deposited per dry weight of experimental cartilage compared with control cartilage in the unoperated knee. (2) Type-II collagen was the radiolabelled product in all samples of experimental cartilage ranging in quality from undamaged to overtly fibrillated, and was the only collagen detected chemically in the matrix of osteoarthrotic cartilage from either dog or human joints. (3) Hydroxylysine glycosylation was examined in the newly synthesized cartilage collagen by labelling dog joints in vivo with [3H]lysine. In experimental knees the new collagen was less glycosylated than in controls. However, no difference in glycosylation of the total collagen in the tissues was observed by chemical analysis. (4) Over half the protein-bound tritium was extracted by 4 M-guanidinium chloride from control cartilage labelled with [3H]proline, compared with one-quarter or less from experimental cartilage. Two-thirds of the extracted tritium separated in the upper fraction on density-gradient centrifugation in CsCl under associative conditions. Much of this ran with a single protein band on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis under reducing conditions. The identity of this protein was unknown, although it resembled serum albumin in mobility afte disulphide-bond cleavage.

Animals↗
PubMed1976

Biochemical changes in the cartilage of the knee in experimental and natural osteoarthritis in the dog.

Biochemical changes in the articular cartilage of the knees of mature dogs, one with natural and four with surgically induced osteoarthritis, have been investigated. The four dogs were killed three, six, nine and forty-eight weeks after division of the right anterior cruciate ligament, the left knees serving as controls. The cartilage of the joints operated on was thicker and more hydrated than the control cartilage; the proteoglycans were more easily extracted and had higher galactosamine/glucosamine molar ratios. The proportion of proteoglycans firmly associated with collagen, and hence not extractable, diminished before fibrillation was demonstrable by indian ink staining of the surface. These biochemical changes were present throughout the entire cartilage of the joints operated on of the dogs killed more than three weeks later, and of the dog with natural osteoarthritis. The results suggest that in response to altered mechanical stresses the chondrocytes synthesise proteoglycans that contain more chondroitin sulphate relative to keratin sulphate than normally, as in immature articular cartilage.

Animals↗
PubMedDate not supplied

Cell, matrix changes and alpha-smooth muscle actin expression in repair of the canine meniscus.

Processes in the repair of a crevice in the knee joint meniscus were investigated in 10 dogs. Two 2-mm cylindrical plugs from each medial meniscus were removed, rendered acellular by freezing and thawing, and then reinserted into the meniscus. Dogs were euthanized at intervals of 3-52 weeks after surgery. The crevice between the plug and meniscus at 3 weeks after surgery was filled with a tissue containing alpha-smooth muscle actin-positive cells. One year after surgery, the plug had remodeled and was populated with spindle-shaped and fibrochondrocyte-like cells. The plug had an appearance intermediate between that of hyaline and fibrocartilage at this time, with a seamless integration in sites between the remodeled plug and the surrounding meniscus. alpha-smooth muscle actin-positive cells were concentrated at the interface of the remodeled plug and adjacent meniscus and at the surface of the plug. Therefore, remodeling of both the plug and meniscal tissue and the participation of alpha-smooth muscle actin-positive cells appear essential for integration of the plug into the adjacent meniscal tissue. Cells in the superficial zone of the meniscus seem to be active in the repair process. A change in both the phenotype of the cells and the quality of the matrix toward a more hyaline state appears to be an integral part of the remodeling process in the meniscus.

Actins↗
PubMedDate not supplied

Meniscal transplantation using fresh and cryopreserved allografts. An experimental study in goats.

A comparative study of three subgroups of meniscal transplants was undertaken in the goat model: Group 1 (autograft) involved removal and immediate reimplantation of the meniscus; Group 2, fresh meniscal allografts; and Group 3, cryopreserved (30 days) meniscal allografts. Six months after surgery, tissues were evaluated for gross degenerative changes, proteoglycan concentration (as assessed by uronic acid), water content, vascularity, histology, and cell viability. The contralateral knee served as control for all comparisons. There was no statistical difference in the amount of arthritis present and all transplants demonstrated an essentially normal peripheral vascularity compared to controls. Sections revealed reduced numbers of cells in the central portions of the transplanted menisci and these viable cells demonstrated different behavior in multiplication in tissue culture compared to contralateral controls. Grossly and microscopically, the implanted menisci differed little from the controls. The measurement of proteoglycan concentration and water content of the transplanted meniscal cartilage suggest alterations that may affect the long-term mechanical properties. The autograft specimens showed the water content was very slightly increased (3% to 6%), while the proteoglycan concentration was increased (42% in terms of uronic acid). In contrast, the water content of the fresh allograft group and the cryopreserved group was increased 12% to 24%. Proteoglycan concentration in these groups was decreased up to 56% in portions of some menisci compared to controls. Fresh and cryopreserved meniscal allografts showed peripheral healing, revascularization, cellularity, and incorporation, and grossly appeared good at 6 months in the goat model. The biochemical changes in the extracellular matrix at 6 months raises questions on the long-term function of these transplanted menisci.

Animals↗