ISSN:0736-0266    

DOI:10.1002/jor.1100130102

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

年代:1995

数据来源: WILEY

ISSN:0736-0266    

DOI:10.1002/jor.1100130103

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe present study was undertaken to examine how osteoarthritis affects the expression of type‐X collagen, a hypertrophic chondrocyte‐specific collagen in articular cartilage. A well characterized sheep polyclonal antiserum, as well as three mouse monoclonal antibodies against canine type‐X collagen, was used to immunolocalize type‐X collagen in human and canine joints. Its expression in osteoarthritic cartilage was altered in several locations. In the canine osteoarthritic joints, type‐X collagen increased in and just above the zone of calcified cartilage and was present diffusely throughout the calcified matrix. In both the human and canine cartilage, type‐X collagen was localized around cell clones in the transitional zone of cartilage. This is surprising, since that region of the cartilage does not calcify and one of the proposed roles of type‐X collagen is in mineralization. Thus, the osteoarthritic process may damage the matrix in the superficial layer and induce changes leading to the expression of the hypertrophic chondroc

ISSN:0736-0266    

DOI:10.1002/jor.1100130104

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

年代:1995

数据来源: WILEY

摘要:

AbstractAlterations in the integrity of the extracellular matrix play an important role in osteoarthritis. Matrix crosslinks in articular cartilage of the knee were studied in partially meniscectomized rabbits to compare changes due to osteoarthritis with those occurring during aging. Pyridinoline, a lysyl oxidase‐initiated crosslink, and pentosidine, a crosslink formed by the Maillard/glycation reaction, were assayed separately on reverse‐phase high performance liquid chromatography. A significant increase in the percentage of insoluble collagen was observed in normal 12‐month‐old rabbits compared with the levels in 3‐month‐old animals, whereas osteoarthritis was associated with a shift toward more soluble fractions. Total pyridinoline content did not change with age or osteoarthritis. Total pentosidine, however, increased significantly with age but remained constant with osteoarthritis. Analysis of the distribution of crosslinks among solubility fractions indicated a significant shift of pyridinoline from the pepsin‐released fraction to the insoluble fraction with osteoarthritis, but no changes were observed with age. Pentosidine distribution shifted toward the pepsin‐released fraction in osteoarthritis, with a shift toward the insoluble fraction with age. Because of the low levels of pentosidine present, its precise location, whether collagenous or noncollagenous, remains unclear. However, since pentosidine represents a marker for the overall Maillard reaction, the results of our studies support a role for Maillard reaction products in the aging of extracellular matrix. The shift of pentosidine toward more soluble fractions suggests the presence of matrix degradation and repair in

ISSN:0736-0266    

DOI:10.1002/jor.1100130105

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe effect of static loading on matrix synthesis was measured in intact bovine coccygeal discs. The discs were maintained at 37°C in a humid atmosphere and were perfused across their upper and lower surfaces for as long as 8 hours with media containing radioisotopes (3H‐proline and35S‐sulphate) via porous filter disks embedded in Perspex (Plexiglas) holders. Static loads were applied to the disc with use of weights. The activity of free, nonincorporated isotope in the centre of the disc was monitored continuously with a microdialysis probe. Incorporated tracer in different regions of the disc was determined at the end of each experiment from the activity of the nondialysable tracer. Free tracer activity rose steeply over the first 3–4 hours of perfusion, as tracer diffused into the disc, and reached a steady value after 5–6 hours, as expected from diffusion theory. The rate of tracer incorporation estimated from the integrated value of free tracer concentration was constant for as long as 8 hours. Incorporation rates varied across the disc: the highest rates were in the inner layer of the annulus fibrosus, and the lowest rates were in the outer layer of the annulus. The rates for both35S‐sulphate and3H‐proline varied with load. The rates were lowest in the nucleus pulposus and the inner layer of the annulus fibrosus with a 0.5 kg load, and they almost doubled as the load was increased to 5–10 kg. Heavier loads (15 kg) led to a decrease in incorporation. Hydration of the disc also varied with load; hydration decreased as load increased and was maintained nearin vivovalues with 5–10 kg of load (0.13–0.26 MN/m2). The effect of load on incorporation rates in the disc is compatible with the suggestion that rates are at a maximum atin vivohydrations and decrease if the hydration decreases or

ISSN:0736-0266    

DOI:10.1002/jor.1100130106

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

年代:1995

数据来源: WILEY

摘要:

AbstractX‐linked hypophosphatemia is a genetic bone disease in humans and mice. Two closely linked mutations in mice.HypandGy. cause low plasma phosphate and a rachitic and osteomalacic bone disease. Because of the controversy as to whetherGyis a good model for X‐linked hypophosphatemia, the phenotypic severity of these two mutations was compared in both sexes and on two genetic backgrounds. The depression in plasma levels of phosphate was similar in all 10‐week‐old mutant mice. MaleHypmice and heterozygous femaleHypmice were affected with similar severity in terms of reduced tail growth, shortened femora, reduced femoral mineral content, and abnormal mineral composition of the femoral matrix. In contrast, maleGymice did not survive on the C57BL/6J background and were more severely affected than femaleGymice on the B6C3H background. The hybrid B6C3H background ameliorated the bone disease compared with the inbred C57BL/6J background for both mutant strains. There was no evidence of change in the plasma levels of 1.25‐dihydroxyvitamin D, duodenal level of vitamin D‐dependent calcium‐binding protein, or urinary level of calcium in these adult mutant mice. In summary,Gymice have a sexual dimorphism not present inHypmice. These two genes may indicate the presence of multiple gene loci in the human disease, with multiple proteins involved in the pathophysiology of the

ISSN:0736-0266    

DOI:10.1002/jor.1100130107

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

年代:1995

数据来源: WILEY

摘要:

AbstractPregnancy and lactation are known to cause structural and mechanical changes in bone, but the effects of pregnancy alone have not been evaluated thoroughly. This study used radiographic measurements, torsion testing, mineral analyses, and histological evaluation to determine whether there are changes in bone material and geometric properties during pregnancy in the growing rat, as implied by earlier biochemical and histological studies. The bones of pregnant 9 to 12‐week‐old rats and controls that were not pregnant and were matched by age (but not weight) were evaluated at times corresponding to 5, 10, 15 and 20 days of the 23‐day gestation period to address the following questions: (a) How is the growth of whole bone affected by pregnancy in the growing rat (as determined by radiographic analyses)? (b) How are the mechanical properties (structural and material) of whole bone affected by pregnancy (as assessed by torsion testing)? (c) Are there changes in the characteristics of bone mineral during pregnancy (as determined by measurement of mineral content and x‐ray diffraction analyses)? and (d) Are there detectable morphological or ultrastructural differences between the bones of pregnant and control rats (as assessed by analyses based on histology and back‐scattered electron imaging)? The presence of statistically significant differences in this study was determined initially on the basis of a two‐factor analysis of variance. In general, significant differences were noted only at late gestation (day 20), when the bones were longer and had a greater outer radius and cortical thickness; this indicates that more growth occurred during pregnancy. At day 20, biomechanical testing showed that the femora of pregnant rats had a 20% decrease in rotational angle to failure and a 30% increase in shear stiffness. No alterations in maximum torque or energy to failure were noted. Calculation of the properties of bone material revealed a 54% decrease in ultimate shear stress, a 50% decrease in shear modulus, and no alteration in shear strain when the bones from rats pregnant for 20 days were compared with controls. The bones of the pregnant rats at day 20 also differed from controls in terms of both mineral characteristics and morphology. X‐ray diffraction showed larger mineral crystallites in the specimens from pregnant rats as compared with controls, whereas the mineral contents (ash weights) were similar. Scanning electron microscopy revealed qualitative differences, including increased periosteal vascularity and numerous large cortical cavities thought to be areas of resorption in the bones from rats pregnant for 20 days as contrasted with controls. These changes are consistent with the observed alteration in mechanic

ISSN:0736-0266    

DOI:10.1002/jor.1100130108

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

年代:1995

数据来源: WILEY

摘要:

AbstractChanges of cytoskeletal architecture and incorporation of3H‐proline were investigated in contracted anterior cruciate ligaments with use of a model of contracture. In control ligaments, fibroblasts were shown by immunofluorescence microscopy to contain actin, vimentin, and myosin in their cytoplasm. Cytoskeletons were visualized by electron microscopy as a mesh network of microfilaments among cell organelles. In contracted anterior cruciate ligaments, fibroblasts were spindle‐shaped and their cytoplasm could not be observed clearly in sections stained with hematoxylin and eosin. Actin staining was distributed irregularly and extensively, whereas vimentin and myosin staining was not scattered so extensively. When compared electromyographically, the actin staining appeared in cytoplasmic pseudopods of the fibroblasts. It was thought that these cytoplasmic pseudopods contained mainly actin and little or no other cytoskeletal elements such as vimentin and myosin. In autoradiographs, contracted anterior cruciate ligaments were shown, with use of3H‐proline, to experience a decrease in the number of labeled cells. On the basis of these findings of cytoskeletal rearrangement and of decreased incorporation of3H‐proline, we hypothesized that fibroblasts of the anterior cruciate ligament had the capacity to change their character during knee immobilization and to play a role in ligament cont

ISSN:0736-0266    

DOI:10.1002/jor.1100130109

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

年代:1995

数据来源: WILEY

摘要:

AbstractTo investigate rates of cellular proliferation and matrix turnover in autogenous flexor tendon grafts, hindlimb intrasynovial (flexor digitorum profundus) and extrasynovial (peroneus longus) tendons were placed within the synovial sheaths of the medial and lateral forepaw digits of 18 dogs and treated with controlled early passive motion. After the dogs had been killed, short‐term culture and labelingin vitrowere utilized to determine rates of DNA, proteoglycan, collagen, and noncollagen protein synthesis. Schiff base covalent collagen crosslink concentrations and total collagen and protein content also were evaluated at intervals through 6 weeks. Tendon grafts of extrasynovial origin showed greater rates of DNA synthesis and significantly elevated levels of proteoglycan, collagen, and noncollagen protein synthesis and Schiff base covalent collagen crosslink concentrations (dihydroxylysinonorleucine) compared with intrasynovial tendon grafts. It was not clear to what extent the increased activity in the extrasynovial graft was due to actual differences between the intrasynovial and extrasynovial tendons or to the responses of the connective tissue surrounding the extrasynovial tendon graft. Since both types of grafts demonstrated similar unaltered levels of collagen and protein content over time, these data suggest greater rates of matrix turnover in tendon grafts of extrasynovial origin than in those of intrasynovial origin. Coupled with previous findings showing increased cellular proliferation in extrasynovial tendon grafts, these data indicate that the process of translation to an intrasynovial environment necessitates a more active process of soft‐tissue repair and remodeling when extrasynovial donor tendons are u

ISSN:0736-0266    

DOI:10.1002/jor.1100130110

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

年代:1995

数据来源: WILEY

摘要:

AbstractDespite the great variability in the clinical behavior of fibrous lesions of the musculoskeletal system, they are composed of cytologically similar fibrocytes. Receptors for estrogen or progesterone, or both, are present in some of these lesions and some increase their rate of growth during periods of high levels of sex steroid hormones. The platelet‐derived growth factor‐B (PDGF‐B) proto‐oncogene encodes the B chain of PDGF, a mitogen for fibrocytes. Tissue from aggressive fibromatosis, fibrous dysplasia, plantar fibromatosis, and recurrent plantar fibromatosis was analyzed with use of the polymerase chain reaction andin situhybridization for the expression of PDGF‐B and PDGF beta receptor. Cell culture was used to determine if estrogen and progesterone stimulation modulated the expression of PDGF‐B. Aggressive fibromatosis, fibrous dysplasia, and recurrent plantar fibromatosis expressed PDGF‐B; plantar fibromatosis, normal plantar fascia, normal fascia lata, and mature scar did not. All of the tissues expressed PDGF beta receptor. The level of expression in aggressive fibromatosis and fibrous dysplasia was four times that in the recurrent plantar fibromatosis. Estrogen and progesterone stimulation in aggressive fibromatosis resulted in an increase in the level of expression. Therefore, the detection of PDGF‐B may be an adjunct in the pathologic identification of locally invasive lesions. Its production may be a common mechanism leading to a fibroproliferative response through deregulation of the control of growth by both paracrine and autoc

ISSN:0736-0266    

DOI:10.1002/jor.1100130111

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

年代:1995

数据来源: WILEY