摘要:

AbstractMany biomechanical and chemical properties of cartilage are dependent on the fixed charge density (FCD) of the extracellular matrix. In this study, nuclear magnetic resonance (NMR) spectroscopy was investigated as a nondestructive technique for determining FCD in cartilage. Sodium content was measured by NMR in cartilage explants and was compared with sodium content measured by inductively coupled plasma emission spectroscopy (ICP) in order to verify the total NMR visibility of sodium in cartilage. The ratio of NMR to ICP results was 1.02 ± 0.04 (calf, mean ± SD, n = 7) and 1.04 ± 0.11 (adult bovine, n = 8). Sodium concentration as measured by NMR was then used with ideal Donnan theory to compute estimates of FCD. For calf articular cartilage (AC) near physiological conditions, calculated FCD was −0.28 ± 0.03M(n = 10). NMR measurements were then made for individual cartilage specimens sequentially equilibrated in baths of differing salt composition, pH, or ionic strength. For calf and adult AC, calculated FCD decreased dramatically between pH 3 and 2, with adult speciments becoming positively charged but calf tissue retaining a net negative charge. For calf AC equilibrated in 0.3–0.015MNaCl, calculated FCD was observed to decrease slightly with decreasing bath ionic strength. For epiphyseal cartilage, FCD varied with the position of origin of the explant within the joint, ranging from − 0.19 to − 0.35Min a manner that correlated with tissue glycosaminoglycan content. Preliminary NMR imaging experiments demonstrated similar variations of sodium concentration in intact ulnar epiphyseal cartilage. Collectively, these results demonstrate the ability of NMR to nondestructively follow FCD in cartilage. The technique is applicable to dynamic studies as well as to both in vitro and in vivo studies on li

ISSN:0736-0266    

DOI:10.1002/jor.1100100102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis article describes the effects of bound forms of insulin‐like growth factors (IGFs) on proteoglycan metabolism by bovine articular cartilage in explant culture. When these growth factors were added to articular cartilage explants complexed with their native serum binding proteins (BPs), both IGF‐I‐BP complex and IGF‐II‐BP complex stimulated proteoglycan synthesis to different degrees over a 3‐day period. When added to the medium of cultures of articular cartilage over 5 days, IGF‐II‐BP complex induced high rates of synthesis and low rates of catabolism of proteoglycans, giving rise to tissue levels of proteoglycan similar to those observed in fresh tissue. When articular cartilage was maintained in culture with the same concentration of IGF‐I‐BP complex, tissue levels of proteoglycans fell over the culture period because of lower rates of proteoglycan synthesis. Analysis of the proteoglycans synthesized by articular cartilage in the presence of free or bound IGF‐I or IGF‐II showed that these growth factors stimulated the rate of synthesis of the large proteoglycan species present in cartilage but did not affect the synthesis of

ISSN:0736-0266    

DOI:10.1002/jor.1100100103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe protective role of hylan, a hyaluronan [hyaluronic acid (HA)] derivative, was studied in explanted bovine cartilage and isolated chondrocytes. Cartilage and chondrocytes were exposed to degradative enzymes (lysate from activated polymorphonuclear leukocytes), oxygen‐derived free radicals (ODFR), conditioned media from mononuclear cells (MCCM), and interleukin‐1 (IL‐1), in the presence and absence of hylan. The effect of HA was also studied. In cartilage explants susceptibility to pertubation was evaluated in terms of35S release and proteoglycan depletion and was compared to control cultures; high viscosity hylan was found to reduce35S release in cartilage explants caused by degradative enzymes, ODFR, MCCM, and IL‐1. The hylan effect was reversible and viscosity‐dependent. In chondrocyte cultures, high viscosity hylan was effective in reducing cell injury caused by degradative enzymes and ODFR. The data suggest that the glycosaminoglycan hylan, as well as native HA, may mediate exposure to and/or response to stimuli associated with initiation of degenerative processes in cartilag

ISSN:0736-0266    

DOI:10.1002/jor.1100100104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe ability of cyclic adenosine monophosphate (cAMP) to maintain differentiated properties of canine articular chondrocytes in culture is reported. Treatment with 0.5 mMdibutyryl cAMP (DBcAMP) caused the cells to adopt a more rounded morphology. This change in morphology seems to have no effect on the overall biosynthetic rates of the cells. After a pulse with35S‐methionine, there was no difference in the concentration of labeled proteins between cultures treated with DBcAMP and control cultures. After 6 days, the amount of fibronectin (FN) in the media of DBcAMP‐treated cultures detected by an enzyme‐linked immunosorbent assay was specifically reduced by 30%. The amount of35S‐FN purified by gelatin‐affinity chromatography decreased 33%. Moreover, the percentage of FN containing the extra domain A sequence was reduced from 19.4 ± 8.7% in control cultures to 9.6 ± 4.2%. Concomitant with the decrease in FN, there was an increase in the concentration of keratan sulfate in the media of DBcAMP‐treated cultures. After 6 days, treated cultures had 47% more keratan sulfate than controls did. These changes appear not to be the result of a change in the deposition of FN or keratan sulfate, because the amount of these molecules that could be extracted from the cell layer was typically below the limit of detection of the assays. Instead, it seems there is a phenotypic change in the chondrocytes pertaining to the production of FN and ke

ISSN:0736-0266    

DOI:10.1002/jor.1100100105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe healing of articular surface defects has been studied with conventional histology, which relies on the staining of the extracellular matrix to identify the phenotype of the cells present. A chondrospecific cellular marker would be useful. S‐100 protein has been found in all chondroid tissues studied, and we evaluated its usefulness in the study of articular cartilage repair. Fullthickness rabbit femoral condylar defects were made, and the specimens were studied at serial time intervals. S‐100 protein staining positively showed chondroid cells in the 7‐ and 14‐day specimens, which were not identifiable by conventional techniques. At 30 and 60 days, an S‐100 positive band of cells separated a deep safranin‐O positive hypertrophic layer from a fibrocellular surface layer. At 120 days, the presence of S‐100 protein identified cells with chondrogenic potential, and the lack of S‐100 protein in other cells embedded in conventionally stained matrix suggested that these cells were no longer of a chondroid phenotype. The presence of S‐100 protein‐identified chondroid cells early in the repair process when the cells had not begun to synthesize conventionally stainable matrix and the lack of S‐100 protein in cells late in the repair positively identified a phenotypic change earlier than c

ISSN:0736-0266    

DOI:10.1002/jor.1100100106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractFor the histopathological classification of the severity of osteoarthritic lesions of cartilage, the Mankin score is frequently used. A necessary constraint on the validity of this scoring system is the consistency with which cartilage lesions are classified. The intra‐ and interobserver agreement of the Mankin score was determined. The intra‐ and interobserver agreement of the 14‐point Mankin score was adequate. Between observers 95% of differences were less than ∼7 points. By a more strict definition of the elements of the Mankin score, the intraobserver differences were reduced only for some observers. The interobserver differences were only slightly reduced: between observers 95% of differences were less than ∼6 points. We found the Mankin score to be an adequate histopatholog

ISSN:0736-0266    

DOI:10.1002/jor.1100100107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe development of the normal human upper tibial growth plate was studied at autopsy in 46 stillborns and 79 newborns of 20–41 weeks gestational age. During this time period, the histology of this plate evolves from a highly cellular structure with relatively poor columnar organization and matrix development to the well known structure seen later in postnatal life. The thickness of the growth plate, assessed in the area surrounding the longitudinal tibial axis, decreases continuously from 1.15 mm on the 20th week to 0.6 mm on the 38th week. This decrease results from losses of both matrix and cellular components, mostly of the latter. However, the relative fraction of area occupied by the matrix significantly increased (12%) and matrix area per cell increased 1.5 times over the last half of gestation, indicating a maturation process of the plate towards a more matrix‐oriented structure with age. In this maturation process the number of cells per unit area does not change and the average size of the cells appears to decrease. Plate thickness does not decrease further in the final 3 weeks of pregnancy and increases in early neonatal life; this has no apparent influence on the tibial growth rate. In the period under study the relative anatomical participation of the upper tibial growth plate decreases from ∼4% of the radiographic length of the tibia on the 20th week to<1% at term. Present data will provide fetal and neonatal growth plate standards needed to obtain a better understanding of this structure during both normal and abnormal condi

ISSN:0736-0266    

DOI:10.1002/jor.1100100108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe innervation of lumbar facet capsule and ligamentum flavum was investigated using antisera to a general neuronal marker protein gene product (PGP) 9.5 and to peptide markers of sensory nerves (calcitonin generelated peptide [CGRP] and substance P) and autonomic nerves (vasoactive intestinal polypeptide [VIP]and C‐flanking peptide of neuropeptide Y [CPON]). In the facet capsule (n = 14), PGP 9.5 and CGRP‐immunoreactive nerves occurred in 12 and five specimens, respectively, both around blood vessels and as free fibers in the stroma. Free fibers immunoreactive for substance P or VIP were noted in three and five specimens, whereas in nine specimens there were CPON‐immunoreactive nerves located perivascularly. There was no immunoreactivity in the ligamentum flavum. This study provides further evidence that the facet capsule but not the ligamentum flavum has substantial innervation by sensory and autonomic nerve fibers and has a structural basis for pain perce

ISSN:0736-0266    

DOI:10.1002/jor.1100100109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractAppearance of a crescent sign usually marks the onset of necrotic femoral head collapse, but very little is known about which local factors contribute most critically to avoiding or postponing fracture of at‐risk juxtaarticular cancellous bone. A three‐dimensional finite element model was used to test the hypothesis that an initially mechanically uncompromised subchondral plate could provide a substantial degree of stress protection to a weakened underlying segmental infarction. The computational simulation of osteonecrosis showed that the principal stress distribution for an assumption of subchondral plate weakening (given also an underlying, comparably weakened segmental infarction) differed inappreciably from that of a normal femoral head. However, the tendency for local structural failure, as reflected in the ratio of stress to strength, was substantially higher in the former instance. If, instead, the mechanical integrity of the subchondral plate overlying the weakened segmental infarction was assumed to be preserved, computed stress levels in the at‐risk subjacent necrotic cancellous bone were still over 70% as high as for the weakened‐plate case. The data thus indicate that even a fully normal subchondral plate can provide only modest stress protection of a weakened underlying segmental infarction, whereas weakening of the necrotic cancellous bone throughout the infarction induces marked stress increase in the overlying subchondral plate. These findings suggest that the onset of collapse is probably dominated much more strongly by the degree of structural degradation of the cancellous bone within the main infarct body, than by the degree of structural degradation within the subchondra

ISSN:0736-0266    

DOI:10.1002/jor.1100100110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis study analyzed processes underlying osteoporosis and osteoarthrosis after short‐term immobilization of the right hind limb of postadolescent (2.8 kg) and mature (4.0 kg) rabbits. After 3 weeks, the lateral posterior aspect of the lateral tibial plateau and the lateral femoral condyle of the immobilized limb exhibited prominent subchondral vascular eruptions. Femoral metaphyseal bone density decreased 27 and 18% in the immobilized limbs of postadolescent and mature rabbits, respectively. Calcein green fluorescence increased 1.9‐fold (p<0.001) in the metaphyseal trabeculae of immobilized femurs. With immobilization, sulfate incorporation into femoral cartilage glycosaminoglycan increased, although total cartilage glycosaminoglycan and hydroxyproline levels were unchanged. Thymidine incorporation into DNA increased four‐ to fivefold in tibial and femoral cartilage of the immobilized limb. In this study, bone loss and remodeling preceded erosive cartilage degrad

ISSN:0736-0266    

DOI:10.1002/jor.1100100111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY