摘要:

AbstractThis 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°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°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 Na2S35SO4incorporation, was diminished to<50% of normal control values immediately following cryopreservation and thawing. Autoradiographic examination of these tissues revealed that only ∼ 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 s

ISSN:0736-0266    

DOI:10.1002/jor.1100060102

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

年代:1988

数据来源: WILEY

摘要:

AbstractWe have formulated a serum‐free medium capable of supporting DNA synthesis in rabbit meniscal fibrochondrocytes at a level equivalent to 10% fetal bovine serum (FBS). The medium consists of a 1:1 mixture of Dulbecco's Modified Eagle's Medium and Ham's F‐12 medium supplemented with transferrin (1 μg/ml), selenium (1 pg/ml), trace metal mix (1:100), dexamethasone (100 ng/ml), insulin‐like growth factors I and II (50 ng/ml each), pituitary fibroblast growth factor (100 ng/ml), and lactalbumin hydrolysate (2 μg/ml). Endothelial cell growth supplement could be substituted for lactalbumin hydrolysate to obtain similar results. Ventrex PC‐1, a commercially available, low‐protein, serum‐free medium, was found to support proliferation of fibrochondrocytes but not as well as 10% FBS or our medium formulation. Lipid supplements, which are known to support the serum‐free growth of hyaline chondrocytes, were found to be either of no value or antagonistic for the culture of fibrochondrocytes. Likewise, vitamin E alone, progesterone, putrescine, and hydrocortisone were also without benefit in our culture system. Thecells had a more chondrocytic morphology when grown in defined medium as opposed to 10% FBS. The results of this study should now make it possible to identify and quantitate those factors necessary to affect meniscal repair by utilizing further tech

ISSN:0736-0266    

DOI:10.1002/jor.1100060103

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

年代:1988

数据来源: WILEY

摘要:

AbstractA cell culture model for studying the cytokine‐mediated degradation of connective tissue was exposed to clinically applied, low‐frequency pulsed electromagnetic fields (PEMF), and levels of collagenolytic activity, two lysosomal hydrolases, and prostaglandin E2were measured. PEMFs reduced the release of two lysosomal enzymes by cultured rabbit synovial fibroblasts but did not affect their response to mononuclear‐cell–conditioned medium. PEMF did not alter levels of cytokine activity produced by a mixed mononuclear cell population, nor did they affect the cytokine‐mediated release of collagenase or prostaglandin E2by synovial fibroblasts. The relevance of these findings to the clinical application of PEMF to soft‐and hard‐tissue injuries

ISSN:0736-0266    

DOI:10.1002/jor.1100060104

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

年代:1988

数据来源: WILEY

摘要:

AbstractI reanalysed data from my previous work to determine the extent to which a model for the loading‐rate dependence of the fracture of cortical bone, put forward by Carter and Caler, fits this independently derived data set. In particular, the extent to which the generality of the model is vitiated by its ignoring the effect of mineralisation on strength was tested. The model was rather strongly corroborated. In addition, the reanalysed data show that yield strain is strongly strain‐rate dependent, but that Young's modulus is rather unvarying over physiological strain rates. The implication of this for hypotheses concerning fracture of bone are discus

ISSN:0736-0266    

DOI:10.1002/jor.1100060105

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

年代:1988

数据来源: WILEY

摘要:

AbstractUsing a three‐dimensional finite element model of a plated long bone, we studied the influence of screw tightness, sliding frictional interfaces, and loading magnitude on the stresses within the plated bone. The model incorporated frictional interface elements that allowed stress‐free separation under tensile loading to occur between the plate and bone and between the screw heads and the plate. The applied loading simulated both static preloads created by tightening the screws that secure the plate to the bone and physiologic loads created by activity. Initial screw tightening with plate application created regions of bone hydrostatic compressive stress that may be partly responsible for ischemia under the plate. The inclusion of frictional interfaces resulted in a nonlinear relationship between physiologic load and bone strain that was dependent on screw tightness. This nonlinear response correlated well with the results of previous in vitro studies showing that slippage between the plate and the bone can occur at physiologic load levels. The results showed that the effect of such slippage can be at least as important as plate meterial, rigidity, and placement in determining the degree of stress shielding. The results also indicated that previous plated bone models that assumed tight interfaces may have overestimated the extent of mechanical stress shield

ISSN:0736-0266    

DOI:10.1002/jor.1100060106

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

年代:1988

数据来源: WILEY

摘要:

AbstractAlthough chemotherapeutic drugs are frequently administered to patient with osteosarcoma, there has been little research into the effect of cytotoxic drugs on osteosarcoma cell biology. The effect of two drugs (Adriamycin and bleomycin) on cell cycle kinetics was investigated in vitro in an established line of human osteosarcoma cells and in vivo using the Dunn osteosarcoma model. The cell cycle changes were consistent with G2arrest for both drugs in vivo and in vitro. The alteration in cell cycle distribution was correlated with inhibition of3H‐thymidine incorporation in vitro. In vivo, the greater change in cell cycle distribution caused by Adriamycin was reflected in the increased inhibition of tumor growth found with this dru

ISSN:0736-0266    

DOI:10.1002/jor.1100060107

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe adhesion of baby hamster kidney 21C/13 fibroblasts to surfaces of passivated titanium, carbon fibers, bioactive glasses B5 and B6, fibronectin‐precoated passivated titanium, and fibronectin‐precoated B6 was quantified. The order of adhesive cell avidity for the uncoated surfaces was passivated titanium (greatest), B6 and carbon fibers (intermediate), and B5 (least). Precoating with fibronectin enhanced the adhesive characteristics of fibroblasts on passivated titanium and B6 by 74% and 118%, respectiv

ISSN:0736-0266    

DOI:10.1002/jor.1100060108

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

年代:1988

数据来源: WILEY

摘要:

AbstractAn experimental model of acute staphylococcal septic arthritis in chickens was used to study the effect of different therapeutic regimens of the antibiotic cloxacillin on the natural history of the disease. Three different theapeutic regimens were used in order to assess the effect of increasing the frequency and of delaying the commencement of administration. The results were assessed by measurement of animal growth rate, clinical condition, bacterial and leukocyte counts in synovial fluid, and histological appearance. An inadequate dosage regimen (a single daily dose) prevented spread of bacteria but did not control abscesses. Delay in commencing treatment permitted persistence and spread of abscesses with destruction of the secondary (epiphyseal) ossification center and even transphyseal spread into metaphyseal bone. Repair by fibroblasts was mainly seen in articular and epiphyseal cartilage but was not seen in the epiphyseal ossification center during the duration of the experiments (up to 18 days). Synovial fluid sampling with measurement of leukocyte and bacterial concentrations appears to be a useful guide to the effectiveness of treatment, because the numbers of cells correlate with the pathological process.

ISSN:0736-0266    

DOI:10.1002/jor.1100060109

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe chemistry and cell biology of the tendon have been largely overlooked due to the emphasis on collagen, the principle structural component of the tendon. The tendon must not only transmit the force of muscle contraction to bone to effect movement, but it must also glide simultaneously over extratendonous tissues. Fibronectin is classified as a cell attachment molecule that induces cell spreading and adhesion to substratum. The external surface of intact avian flexor tendon stained positively with antibody to cellular fibronectin. However, if the surface synovial cells were first removed with collagenase, no positive reaction with antifibronectin antibody was detected. Analysis of immunologically stained frozen sections of tendon also revealed fibronectin at the tendon synovium, but little was associated with cells internal in tendon. The staining pattern with isolated, cultured synovial cells and fibroblasts from the tendon interior substantiated the histological observations. Analysis of polyacrylamide gel profiles of35S‐methionine‐labeled proteins synthesized by synovial cells and internal fibroblasts indicated that fibronectin was synthesized principally by synovial cells. Fibronectin at the tendon surface may play a role in cell attachment to prevent cell removal by the friction of gliding. Alternatively, fibronectin, with its binding sites for hyaluronic acid and collagen, may act as a complex for boundary lubricat

ISSN:0736-0266    

DOI:10.1002/jor.1100060110

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

年代:1988

数据来源: WILEY

摘要:

AbstractTendons transmit the force of muscle contraction to bone to effect limb movement. Special structural and biological properties of tendon have developed to facilitate force transmission. The tendon has a complex organization of cells surrounding the collagen bundles inside tendon as well as at the tendon surface. Internal cells may act to maintain the bulk of the collagen in tendon. External cells in the epitenon may provide lubrication for tendon gliding. To develop better understanding of these processes and the roles the cell populations play, we isolated cells from the surface and interior of tendon and studied them in vitro. Flexor tendons from 8‐week‐old white Leghorn chickens were separated into two distinct cell populations: the outer synovial cells and the fibroblasts more internal in tendon. These cell populations were discernible by their locations in the intact tendon, determined by sequential enzymatic and physical release from their substrata. Initially, some cells eluted in Hanks' salt solution (HSS) (population 1); then synovial cells were released after a 2‐min treatment with 0.5% collagenase (population 2). Next, a population of synovial cells was released in high yield by treatment with 0.25% trypsin (step III, population 3). Step III, population 3 cells were used as synovial cells (SCs). Next, a population of SCs and fibroblasts were released by scraping with a rubber policeman (population 4). Subsequently, fibroblasts were released after incubation with 0.5% collagenase (population 5). A more direct procedure (procedure 2) to isolate the synovial and internal tendon cells involved treatment in 0.5% collagenase followed by sedimentation at 900 g. Cells that sedimented were largely fibroblasts, whereas the cells that remained at the top of the tube were largely SCs. Cells designated as SCs, isolated by procedure 2, most likely contained surface cells from epitenon and internal interfascicular cells from endotenon and paratenon. Surface tendon cells separated by sequential enzymatic and physical release from their substrata (by procedure 1) had all the following characteristics: distinct subpopulations of cells based on morphology; presence of cytoplasmic, lipid‐containing vesicles; decreased sensitivity to trypsin; and reduced generation time as compared with that of internal fibroblasts. Conversely, the internal fibroblasts (IFs) appeared to represent a more uniform population based on morphological characte

ISSN:0736-0266    

DOI:10.1002/jor.1100060111

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

年代:1988

数据来源: WILEY