摘要:

AbstractThe study was designed to determine the contents and distributions of the proteoglycans decorin and biglycan in adult human femoral condylar cartilage and whether these may change in osteoarthritis. New radioimmunoassays were established using peptides representing the amino‐terminal 21 amino acid sequence of each proteoglycan (to which a tyrosine was added for radioiodination) and antibodies in a rabbit antiserum raised to both these molecules. Cartilage was extracted with 4Mguanidine HCl to determine total content, and extracts were analyzed by chromatography to determine molecular sizes. Frozen sections were cut parallel to the articular surface and were extracted to determine distribution within the tissue. Gel chromatography on Sepharose CL‐2B under dissociative conditions revealed molecules with a partition coefficient of 0.7–0.75 in both normal and osteoarthritic cartilage. In normal adult cartilage, the mean contents of the core proteins of biglycan and decorin were calculated to be approximately 0.34 and 0.48 mg per gram wet weight, respectively. These represented molar contents similar to that of aggrecan. In osteoarthritic cartilage, there were no overall significant changes in the content and distribution of these molecules. There was, however, considerable individual variation in both distribution and content. Analyses indicated that there was a trend in osteoarthritic cartilage toward a loss of biglycan and decorin from the more superficial layers of intact cartilage, where both these molecules are normally more concentrated. This was accompanied by maintenance of proteoglycan content deeper in the cartilage, regardless of the degree of degener

ISSN:0736-0266    

DOI:10.1002/jor.1100140502

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

年代:1996

数据来源: WILEY

摘要:

AbstractThe present study was undertaken to investigate the effect of insulin‐like growth factor‐1 on proteoglycan synthesis and the autocrine/paracrine mechanisms involving insulin‐like growth factor‐1 in the bovine coccygeal intervertebral disc. Insulin‐like growth factor‐1 stimulated proteoglycan synthesis in cultured cells of the nucleus pulposus of bovine intervertebral discs in a dose‐dependent manner, and the effect was inhibited by an anti‐insulin‐like growth factor‐1 monoclonal antibody.In situhybridization histochemistry revealed the expression of insulin‐like growth factor‐1 mRNA in the cultured cells, and its production in these cells was demonstrated by radioimmunoassay. Insulin‐like growth factor‐1 receptor in the cultured cells was also demonstrated immunohistochemically. Scatchard analysis using an [125I]insulin‐like growth factor‐1 binding assay showed that the cells cultured in monolayer had a single type of insulin‐like growth factor‐1 receptor, whose affinity and number were estimated to be 7.38 × 108/Mand 9.27 × 104/cell, respectively. These results suggest that insulin‐like growth factor‐1 stimulates proteoglycan synthesis in cells of the nucleus pulposus and that these cells in culture have an insulin‐like growth factor‐1 autocrine/paracrine mechanism. The expressions of insulin‐like growth factor‐1 mRNA and insulin‐like growth factor‐1 receptor in disc tissue were greater in cells of the nucleus pulposus of fetal bovine intervertebral discs than in those of the adult discs. These findings suggest that the action of autocrine/paracrine insulin‐like growth factor‐1 is more active in cells of th

ISSN:0736-0266    

DOI:10.1002/jor.1100140503

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

年代:1996

数据来源: WILEY

摘要:

AbstractThe development of several types of human tumors is related to amplification of genes that are involved in cell growth. The protein products of these genes give the cells a selective growth advantage. The q13–15 region of chromosome 12 is frequently altered in human sarcomas, and the SAS gene has been identified in an amplification unit mapping to this region. Gene amplification of SAS was analyzed to determine the frequency of genetic alteration of this gene in osteosarcoma. Using Southern blot analysis as well as quantitative polymerase chain reaction. SAS was found to be amplified in 10 (36% ) of 28 osteosarcomas. Gene amplification was evaluated in subtypes of osteosarcoma. All seven surface osteosarcomas displayed amplified SAS. In contrast, SAS was amplified in only two (13% ) of 15 intramedullary osteosarcomas. The finding that all surface osteosarcomas demonstrated SAS gene amplification suggests that this gene may play a role in the pathogenesis of osteosarcoma subtypes and that surface osteosarcoma may be genetically different from high‐grade intramedullary osteosarc

ISSN:0736-0266    

DOI:10.1002/jor.1100140504

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

年代:1996

数据来源: WILEY

摘要:

AbstractThe dynamics of longitudinal bone growth are very complex, and potential targets for control could be any one of a number of cells or physiologic processes. Previous studies have demonstrated a linear relationship between hypertrophic cell morphology and bone growth rate in various growth plates and animals. It is unclear whether this relationship varies with age or growth plate. This study tested for significant correlations between mean terminal hypertrophic cell volume and bone growth rate as a function of age and growth plate in the New Zealand White rabbit. Three male rabbits in each of five age groups (2, 3, 5, 8, and 12 weeks old) were used to analyze growth plates from the proximal femur, proximal tibia, and proximal and distal radius. With use of tetracycline labeling and stereological techniques, bone growth rates and hypertrophic chondrocyte volumes were measured. The data were stratified by age and growth plate location and were analyzed using linear regressions. Analyses of covariance were used to test for significant differences. First, there were significant differences due to age. Linear relationships between bone growth rate and hypertrophic chondrocyte volume existed only for the older age groups (all r2>0.8), not for the 2 or 3‐week‐old groups. Also, the slope of the relationship was significantly higher in 5‐week‐old rabbits than in the 8 and 12‐week‐old groups, Second, there were significant differences between species. A comparison of the rabbit data with pig and rat data in the literature showed significant differences between all three species. Third, significant differences between growth plates were found. Although hypertrophic chondrocyte volume plays an important role in bone growth, its function may be dependent on age, species, a

ISSN:0736-0266    

DOI:10.1002/jor.1100140505

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

年代:1996

数据来源: WILEY

摘要:

AbstractAn autosomal dominant mutation in the COL2A1 gene was identified in a child with the Kniest form of spondyloepiphyseal dysplasia. A C to T transition at nucleotide 35 of exon 12 changed the codon GCG for alanine 102 of the triple helical domain of α1 (II) chains of type‐II collagen to GTG for valine. The transition also introduced a GT dinucleotide into exon 12. Analysis of cDNA prepared from Kniest cartilage showed thatin vivothe transition resulted in an alternatively spliced mRNA that lacked the 21 3′ nucleotides from exon 12. The cartilage cDNA contained approximately equal amounts of normal cDNA and shortened mutant cDNA. The deletion of 21 nucleotides from the mutant cDNA maintained the translational reading frame but resulted in the loss of alanine 102 to lysine 108, which interrupted the repetitive glycine‐X‐Y triplet sequence required for formation of the triple helix. Type‐II collagen molecules containing one or more mutant chains were expected, therefore, to contain interrupted triple helices with a short amino‐terminal helical domain A and a large carboxy‐terminal helical domain B. Kniest cartilage contained a reduced amount of pepsin‐solubilized type‐II collagen that consisted of overmodified α1 (II) chains. Peptide mapping showed that the overmodifications extended to the carboxy terminus of the α1(II) chains. Pepsin digestion also yielded shortened α1 (II) chains corresponding to helical domain B, Kniest chondrocytes cultured in alginate beads produced type‐II collagen that was not stably incorporated into the pericellular matrix. This study highlights the importance of dominant negative mutations of COL2A1 in pro

ISSN:0736-0266    

DOI:10.1002/jor.1100140506

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

年代:1996

数据来源: WILEY

摘要:

AbstractPalmar fibromatosis (Dupuytren contracture) causes fibrosis of specific palmar fascial bands. These bands are subjected to repetitive mechanical strainin situ. Primary cell cultures were derived from (a) palmar fibromatosis from eight patients, (b) uninvolved palmar fascia (Skoog's fibers) from four of these patients and (c) normal palmar fascia from four additional patients. The cells were plated onto collagen‐coated membranes either subjected to cyclic strain (25% maximal strain at 1 Hz) or without strain. Bromodeoxy uridine incorporation showed an increase in proliferation in all cultures subjected to strain. This increase was highest for palmar fibromatosis (10 to 40% nuclear incorporation, p = 0.02). Skoog's fibers and fascia from the normal individuals showed a trend (not significant) toward increase with strain (8 to 25%, p = 0.15 for Skoog's fibers, and 8 to 15%, p = 0.45 for normal fascia). Cyclic strain increased the expression of platelet derived growth factor‐A relative to glyceraldehyde‐3‐phosphate dehydrogenase in palmar fibromatosis (2.2 to 3.5, p = 0.05) and Skoog's fibers (0.8 to 2.0, p = 0.04). The expression of platelet‐derived growth factor‐B relative to glyceraldehyde‐3‐phosphate dehydrogenase was enhanced by cyclic strain only in the fibromatosis tissue (0.7 to 2.1, p = 0.04). The normal fascia did not express platelet‐derived growth factor. Platelet‐derived growth factor neutralizing antibody decreased bromodeoxyuridine incorporation in fibromatosis cultures subjected to cyclic strain to near levels for those grown in the absence of strain (38 to 16%, p = 0.05). Conditioned medium from fibromatosis cells grown under stain showed a trend toward increased proliferation in additional fibromatosis cultures compared with conditioned medium from fibromatosis cells grown without strain (9 to 15% nuclear incorporation, p = 0.20). The observed palmar fibromatosis contracture can be partially explained on the basis of the cell's response to cyclic strain, which may be mediated by plateletde

ISSN:0736-0266    

DOI:10.1002/jor.1100140507

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

年代:1996

数据来源: WILEY

摘要:

AbstractThe influence of signal pathways involved in the adhesion of fibroblasts from the anterior cruciate and medial collateral ligaments to fibronectin was investigated. Specific emphasis was paid to the cyclic adenosine monophosphate and Ca2+/phospholipid pathways to determine the signaling mediated by integrin receptors during cell binding and spreading on a fibronectin‐coated glass surface and to compare the roles of these two pathways in integrin‐mediated adhesion in fibroblasts from the two ligaments. Individual cell adhesion strengths were determined using a micropipette‐micromanipulation system after the cells were treated with signal pathway inhibiting agents. Adhesion in fibroblasts from the medial collateral ligament was significantly reduced by inhibiting agents for Giprotein, protein kinase A, protein kinase C, protein kinase G, phospholipase C, and calmodulin, which suggests a crucial role for cyclic adenosine monophosphate and Ca2+/phospholipid signaling in integrin‐mediated adhesion of these fibroblasts. Adhesion in fibroblasts from the anterior cruciate ligament, however, was reduced only by a protein kinase C inhibiting agent and was increased by inhibiting agents for protein kinase A, protein kinase G, and calmodulin, which suggests only a partial role of Ca2+/phospholipid signaling in integrin‐mediated adhesion of these fibroblasts. On the basis of additional parallel studies on the role of intracellular calcium in integrin‐mediated adhesion, medial collateral ligament and anterior cruciate ligament fibroblast adhesion was calcium dependent throughout the 60 minute time course of adhesion experiments. Fibroblasts from the medial collateral ligament demonstrated a 2.2‐fold increase in cytosolic free calcium upon binding to fibronectin, whereas fibroblasts from the anterior cruciate ligament demonstrated no significant increase in calcium. Overall, the study of the intrinsic differences between anterior cruciate ligament and medial collateral ligament fibroblasts in their signal pathways upon binding to fibronectin may reveal information important for further explaining the lack of functional healing response in the anterior cruciate ligament

ISSN:0736-0266    

DOI:10.1002/jor.1100140508

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

年代:1996

数据来源: WILEY

摘要:

AbstractIn previous studies, platelet‐derived growth factor has demonstrated beneficialin vivoeffects on wound healing. We report the results of two studies of platelet‐derived growth factor in the rat medial collateral ligament injury model. Experimental injury sites were implanted with platelet‐derived growth factor, whereas contralateral controls received only collagen. Twelve days postoperatively, the femur‐medial collateral ligament‐tibia complex was tested mechanically. Our first study found a marked drop in the effectiveness of platelet‐derived growth factor when it was administered more than 24 hours after injury. Dose‐response testing showed maximum increases in strength (90% ) with 5.0 μg of platelet‐derived growth factor, but the 1.0 μg group showed similar strength increases, indicating a probable plateau effect in the response. These results indicate that platelet‐derived growth factor has promise for healing ligaments but that it must be administered in appropriate dose

ISSN:0736-0266    

DOI:10.1002/jor.1100140509

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

年代:1996

数据来源: WILEY

摘要:

AbstractThe toxicity of tobramycin at concentrations released from antibiotic‐impregnated polymethylmeth‐acrylate beads was determined using cultured embryonic chick tibiae. Because previous results from this laboratory have shown that osteoblast metabolism is inhibited at low pH and because of the potential for a low local pH in infected bone, the antibiotic was tested in medium with pH values from 6.8 to 7.4. Bone metabolism was evaluated by measuring the rates of glycolysis (lactate production), protein synthesis ([3H]proline uptake), and collagen synthesis ([3H]proline hydroxylation). Tobramycin at the concentrations released from the beads (1.0–1.5 mg/ml) contributed to lowering the pH of the medium. At pH 7.4, the antibiotic produced as much as a 30, 39, and 48% decrease in glycolysis, protein synthesis, and collagen synthesis, respectively. Tibiae exposed to tobramycin for 3 days, followed by 2 days without the antibiotic, showed only a partial recovery from its toxic effects. Although tobramycin was relatively less toxic in an acidic environment, the overall metabolic activity of the bones was poorest when the tobramycin concentration was high (2.0 mg/ml) and pH was low (6.8). The results of this study support the following conclusions: (a) tobramycin at high concentrations is toxic to bone, (b) a combination of high tobramycin concentration and low pH in the bone microenvironment may greatly inhibit bone metabolism, and (c) treatment and prevention of osteomyelitis by means of tobramycin‐impregnated beads may be augmented by preventing the pH from decreasing in traumatize

ISSN:0736-0266    

DOI:10.1002/jor.1100140510

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

年代:1996

数据来源: WILEY

摘要:

AbstractLocal delivery of antibiotics by a degradable carrier has the potential for high local antibiotic levels and avoids systemic toxicity. Intravenous access, renal function monitoring, and subsequent surgical removal may not be required when degradable local delivery modalities are used. This study examined thein vivoelution of gentamicin from processed bovine collagen (type I) in 66 adult White rabbits. Collagen impregnated with gentamicin (3 mg/kg) was implanted into the vastus lateralis, and data were collected from 15 minutes to 28 days after implantation. Local tissue biopsies were taken a minimum of 2 mm from the implantation site. The gentamicin was released into the local tissue and averaged more than 3,800 μg/ml during the initial 4 hours after implantation. Local levels fell to 6.90 ± 5.22 μg/ml at 24 hours and subse‐quently were 2.70 ± 1.75. μg/ml or more through day 28. Serum levels reached an average peak of 4.04 ± 1.75 μg/ml at 5 hours after implantation, decreased after the initial 24 hours, and subsequently were less than 0.41 ± 0.20 μg/ml through day 28. Collagen impregnated with gentamicin proved to be an effective degradable carrier of gentamicin in the healthy rabbit; it provided local tissue concentrations above the minimum inhibitory concentration and serum concentrations below levels associated with systemic toxicity for 28 days after im

ISSN:0736-0266    

DOI:10.1002/jor.1100140511

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

年代:1996

数据来源: WILEY