摘要:

AbstractThe biosynthetic response of calf articular cartilage explants to dynamic compression was examined over a wide range of amplitudes, waveforms, and frequencies. Glycosaminoglycan synthesis was assessed by35S‐sulfate incorporation, and amino acid uptake and protein synthesis were assessed by3H‐proline incorporation. Two culture chambers were designed to allow uniaxial radially unconfined compression and mechanical testing of cartilage disks: one chamber was used inside a standard incubator; the other was used with a mechanical spectrometer and allowed load and displacement to be monitored during compression. Dynamic stiffness measurements of 3‐mm diameter disks identified a characteristic frequency [0.001 Hz (cycles/sec)] that separated low‐ and high‐frequency regimes in which different flow and deformation phenomena predominated; e.g., at 0.0001–0.001 Hz, significant fluid was exuded from cartilage disks, whereas at 0.01–1 Hz, hydrostratic pressure increased within disks. At the higher frequencies, oscillatory strains of only ∼1–5% stimulated3H‐proline and35S‐sulfate incorporation by ∼20–40%. In contrast, at the lower frequencies (a) compressions of<5% had no effect, consistent with the dosimetry of biosynthetic inhibition by static compression (∼25% compression caused a ∼20% inhibition of radiolabel incorporation), and (b) higher amplitudes (cycling between disk thicknesses of 1.25 and 0.88–1.00 mm) stimulated3S‐sulfate incorporation by ∼20–40%, consistent with the kinetics of response to a single 2‐h compression and release. None of the compression protocols was associated with detectable alterations in (e.g., compression‐induced depletion of) total glycosaminoglycan content. This study provides a framework for identifying both the physical and biological mechanisms by which dynamic compression can modulate chondrocyte biosynthesis. In addition, the culture and compression methodology potentially allows in vitro evaluation of clinical strategies of continuous passive motion

ISSN:0736-0266    

DOI:10.1002/jor.1100070502

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

年代:1989

数据来源: WILEY

摘要:

AbstractNormal and stored articular cartilage from the medial tibial plateaus of mature canine knee joints were evaluated histologically and biomechanically. The medial plateaus from the right knee (control) were assessed fresh, while the left (stored) were preserved in culture media at 4°C for 3, 7, 14, or 28 days and then evaluated. Biomechanically, confined compression tests were performed on all specimens to determine the aggregate modulus and apparent permeability of the articular cartilage. Histologically, Safranin O– and hematoxylin and eosin (H&E)–stained sections were evaluated. All stored cartilage specimens had an aggregate modulus on average lower than normal, but the differences were not significant (p>0.10). The apparent permeability was on average higher than but also not significantly different from normal (p>0.10). Time in storage (up to 28 days) did not have a significant effect on the biomechanical properties of stored cartilage normalized by control values (p>0.50). Safranin O and H&E histological evaluation also showed no overall changes in cell appearance or staining of the stored cartilage when compared with control for the time periods stu

ISSN:0736-0266    

DOI:10.1002/jor.1100070503

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

年代:1989

数据来源: WILEY

摘要:

AbstractWe have studied the effect of environmental sulfate concentration on the glycosaminoglycan synthesis of anatomically intact patellar cartilage of the mouse in vitro. Incubation of mouse patellae in medium with sulfate concentrations below 0.5 mMresulted in a diminished incorporation of sulfate but in unaltered incorporation of glucosamine. This suggested the synthesis of undersulfated glycosaminoglycans under these conditions. We characterized glycosaminoglycans synthesized at three different sulfate concentrations: a sulfate concentration physiological for the mouse (1.0 mM), a sulfate concentration in the range where sulfate incorporation was strongly diminished (0.1 mM), and an extremely low sulfate concentration (10 nM). Analysis of glycosaminoglycan disaccharides and DEAE anion chromatography of the glycosaminoglycans could not confirm the synthesis of undersulfated glycosaminoglycans at 0.1 mM. The chromatogram of glycosaminoglycans synthesized in medium containing 10 nMshowed the presence of a very low sulfated glycosaminoglycan pool not observed at higher medium sulfate concentrations. Intermediately sulfated glycosaminoglycans were also synthesized during incubation with 10 nMsulfate. So, our data indicate that only very low sulfate concentrations in the medium lead to the synthesis of undersulfated glycosaminoglycans and that the sulfation mechanism of murine patellar cartilage chondrocytes does not seem to fit completely in an “all‐or‐nothing”

ISSN:0736-0266    

DOI:10.1002/jor.1100070504

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

年代:1989

数据来源: WILEY

摘要:

AbstractIn the distal hypertrophic cell zone of growth plate cartilage, the penetration of metaphyseal vascular endothelial cells is into the noncalcified territorial and pericellular matrices. Cellular mechanisms that promote metaphyseal vascularization are understood poorly, partly because no study has addressed the question of the time sequence of cellular interactions at the chondro‐osseous junction. The purpose of the present study is to make predictions about the relative and the real time duration of cellular events during vascular invasion, including an analysis of the time sequence of death of the terminal hypertrophic chondrocyte. The data from serial section analysis at the light microscopical level of tetracycline‐labeled growth plates indicate that death of the terminal hypertrophic chondrocyte occurs in discrete morphological stages characterized by rapid cellular condensation followed, within minutes, by endothelial cell penetration into the vacated lacuna. Cellular condensation lasts ∼45 min or 18% of the time a cell spends as a terminal chondrocyte. The data also demonstrate that chondrocytic death occurs prior to invasion by vascular endothelial cells and that the chondrocytic lacuna remains empty for as long as 15 min before an endothelial cell or blood vascular cell fills the

ISSN:0736-0266    

DOI:10.1002/jor.1100070505

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

年代:1989

数据来源: WILEY

摘要:

AbstractTensile tests to failure were performed on the distal femoral growth plate of rabbits. The measured tensile forces, together with animal weight and dimensional measurements of the femur, were used to develop a noninvasive method of predicting growth failure loads and to examine the effects of age on the tensile strength of the growth plate. Growth plate failure load correlated with rabbit weight, (r= 0.93), femoral length, (r= 0.91), and contoured growth plate surface area, (r= 0.74). Regression analysis for these relationships allowed for failure load prediction if animal weight, femoral length, or growth plate surface area was known. Nominal stress (failure load/surface area) was calculated and correlated with animal weight (age) for each distal femoral growth plate utilizing two surface area estimating techniques; growth plate surface contour and growth plate cross‐sectional enlargement. A strong association was found with either technique. The growth and maturation of growth plate cartilage is of major importance in pediatric orthopaedics. This study demonstrated that the age‐dependent increases in tensile mechanical properties of the growth plate do not result merely from growth plate enlargement or conformational changes. The changing tensile mechanical properties of the growth plate may explain why transphyseal distraction used clinically has produced varied and somewhat unpredictable results. Our study suggests that dose‐response investigations are needed to define safe and optimal transphyseal distraction tensions before further clinical application is pu

ISSN:0736-0266    

DOI:10.1002/jor.1100070506

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

年代:1989

数据来源: WILEY

摘要:

AbstractFollowing primary hindlimb amputations dividing the lower femur or the central tibiofibula, the neonatal rat innately regenerates the distal growth plate(s) with a frequency of about 20–30%. One or two reamputation procedures were performed in an effort to increase the frequency of physeal regeneration, noting that such procedures, and related forms of tissue stimulation, have been repeatedly shown to induce regenerative growth at limb amputation sites of some amphibians that display little innate regenerative capacity. The present reamputation sequences divided the skeletal stump through the cartilaginous mass arising at its distal end. Following first reamputation an approximate three fold increase in the frequency of growth plate cartilage regeneration was observed at transfemoral and transtibiofibular sites. Only after second reamputation, however, did tibiofibular physeal cartlage regeneration equal in frequency that observed after first reamputation through the lower femur. Ectopic growth plate cell architecture was identified in cartilaginous extensions arising from the side of the distal femoral shaft, and also within the regrown secondary cartilage body, which unites the lower tibia and fibula in the shank of the rat. Moreover, among 3 of 11 femoral amputees that had sustained reamputations, regrowth of the distal femoral condylar mass and profile were achieved to varying degrees. It is concluded that a regimen of reamputation, known to induce regenerative growth in the amphibian limb, also induces skeletal regeneration in the mammalian limb, and leads to the appearance of ectopic growth plate cell architecture at adjacent site

ISSN:0736-0266    

DOI:10.1002/jor.1100070507

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

年代:1989

数据来源: WILEY

摘要:

AbstractViscoat, a high‐molecular‐weight, highly purified hyaluronic acid (HA) and chondroitin sulfate (CS) compound, was instilled around rabbit plantaris tendon following full‐thickness laceration and surgical repair. After 3 weeks of immobilization, no significant difference in adhesion strength or tensile strength of the healing tendons existed between Viscoat‐treated tendons and controls. This contradicts previous studies which suggest that hyaluronic acid reduces postoperative tendon adhesions. Further studies examining tendon adhesions after less severe degrees of tendon injury and using direct, quantitative measurement techniques are warranted to demonstrate whether HA has a beneficial effect on tendon

ISSN:0736-0266    

DOI:10.1002/jor.1100070508

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

年代:1989

数据来源: WILEY

摘要:

AbstractTwo, three, or four intercostal nerves with their vasoconstrictive sympathetic fibers were resected on the right side of 15 growing rabbits. Animals submitted to sham operations and intact animals formed two control groups. A scintigraphic study with99mTc‐methylene diphoshonate, performed on the test group 2 months after the resection, showed a significantly greater uptake of the isotope on the right than on the left costochondral junctions (p<0.05). Three months later the difference was still larger. There was no such significant difference in the rabbits of the two reference groups. In the rabbits of both these groups, the right and left ribs of each pair were almost equal in length. Of the denervated ribs of the rabbits composing the test group, the right ribs increased in length to a greater extent than the corresponding left ribs. The difference was statistically significant (p<0.05). As a consequence of this left‐right difference in length, mild thoracic scoliosis convex to the left developed 2 months after the resection. The total weight and volume of the denervated right ribs increased significantly more than those of the corresponding control left ribs (p<0.05), but their mineral content per unit of weight or volume showed no significant differe

ISSN:0736-0266    

DOI:10.1002/jor.1100070509

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

年代:1989

数据来源: WILEY

摘要:

AbstractAddition of 50 μg/ml sodium ascorbate to confluent cultures of isolated rat calvarium bone cells resulted in a 21% increase in DNA production, a 50–60% increase in incorporation of [14C]proline into collagenous and noncollagenous proteins, and a 200% increase in alkaline phosphatase activity; under identical conditions, [35S]sulfate incorporation into proteoglycans (glycosaminoglycans) was not affected. These results suggest that ascorbate may be important in maintaining or stimulating the osteogenic phenotype of normal bone cel

ISSN:0736-0266    

DOI:10.1002/jor.1100070510

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe axial rotation (rotation about a vertical axis) of the vertebrae, of the ribs, and of the back surface are components of the deformity recognized clinically as the “rib hump” in thoracic scoliosis. Relationships of these rotations to the lateral deviation and lateral curvature of the spine were studied in 40 patients with idiopathic scoliosis. Stereoradiographs of the spine and rib cage were used to measure three components of axial rotation: rotation of the vertebrae, of the rib cage, and of the plane of maximum curvature of the spine. Stereotopographs of the back surface were digitized to measure the axial rotation of the back surface.In individual patients, there were high correlations of all components of axial rotation at each spinal level with the corresponding vertebral lateral deviation from the spinal axis. By regression analyses of the maximum values of each rotation in each curve, the rotation of the apex vertebra was found to be generally of lesser magnitude than the rotation of the plane of maximum curvature of the spine and in an opposite sense in kyphotic curves. The rib cage rotation was generally of lesser magnitude than the vertebra rotation, and the back surface rotation was less than both of these skeletal rotations.Vertebra rotation correlated most closely with lateral deviation of the spine. Simple segmental coupling of axial rotation and lateral bending could not be responsible for this axial rotat

ISSN:0736-0266    

DOI:10.1002/jor.1100070511

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

年代:1989

数据来源: WILEY