bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure of chondroitin sulfate on aggrecan isolated from bovine tibial and costochondral growth plates
Authors: Deutsch Angela J. , Midura Ronald J. , Plaas Anna H. K. 
Published: February 2005

AbstractThe structure of chondroitin sulfate on aggrecan isolated from the rib and proximal tibial growth plates of bovine fetuses was investigated, and the previously reported increase in the hydrodynamic size of chondroitin sulfate chains between the reserve and hypertrophic zones of the rib was confirmed in the tibial growth plate. Superose 6 gel chromatography, calibrated for chondroitin sulfate chain length by monosaccharide analysis, showed that the average molecular mass of chondroitin sulfate in the reserve and maturing zones of both growth plates was 21,600 and 30,400, respectively. Determination by capillary zone electrophoresis of the disaccharide composition of chains following chondroitinase digestion showed that ΔDi‐0S, ΔDi‐4S, and ΔDi‐6S together accounted for more than 98% of the disaccharides in the digests from all zones of both growth plates; Δdisulfated and Δtrisulfated disaccharides were not detected. Furthermore, this analysis revealed a gradient in chondroitin sulfate composition from the reserve to the hypertrophic zone, characterized by a marked increase in the content of ΔDi‐6S (from about 32% to about 52%) and a marked decrease in the content of ΔDi‐4S (from about 53% to about 35%). Moreover, this altered pattern of sulfation was detected on chains of all sizes in the hypertrophic zone, suggesting that a proportion of the reserve zone aggrecan might be removed and replaced with aggrecan rich in chondroitin‐6‐sulfate synthesized during the proliferative and maturation stages of the resident chondrocytes. These data are discussed in relation to the biosynthetic mechanisms that control chondroitin sulfate chain length and sulfation on aggrecan and their modification during chondrocyte proliferation, maturation, and hypertrophy in the growth plate.
Subchondral bone density in the human elbow assessed by computed tomography osteoabsorptiometry: A reflection of the loading history of the joint surfaces
Authors: Eckstein Felix , Müller‐Gerbl Magdalena , Steinlechner Martin , Kierse Robert , Putz Reinhard 
Published: February 2005

AbstractThe functional adaptation of bone tissue to the mechanical stresses acting on it has been convincingly established. This association should apply as well to the subchondral bone, reflecting the long‐term distribution of stress over the joint surfaces. Thirty‐six specimens of the human elbow joint were investigated by computed tomography osteoabsorptiometry in order to assess the distribution of he subchondral mineralization. The distal surfaces usually were more highly mineralized than the proximal components of the joint, whereas the humeroulnar and the humeroradial parts exhibited a similar degree of mineralization. The fovea of the radial head always showed a central density maximum, and the trochlear notch usually presented a bicentric distribution pattern, with maxima beneath the ventral and dorsal regions of the articular surface. The different patterns of subchondral mineralization were shown to reflect the loading history of the overlying articular surfaces, which is determined mainly by geometrical factors. The flatter socket of the humeroradial joint leads to central load transmission, but the deeper socket of the humeroulnar joint will, by contrast, give rise to bicentric stress distribution.
Co‐contraction of lumbar muscles during the development of time‐varying triaxial moments
Authors: Thelen D. G. , Schultz A. B. , Ashton‐Miller J. A. 
Published: February 2005

AbstractThe recruitment and co‐contraction of lumbar muscles were investigated during the voluntary development of slowly and rapidly varying trunk flexion and extension, lateral bending, and axial twisting moments. Myoelectric signals were recorded from 14 lumbar muscles in nine young men during maximum voluntary exertions and cyclic isometric exertions. System identification techniques were used to calibrate dynamic models of the relationship between myoelectric signals and force. To assess co‐contraction, the predicted muscle forces were subdivided into a task‐moment set of muscle forces that minimally satisfied moment equilibrium and a co‐contraction set of muscle forces that produced zero net moment. The sum of co‐contraction muscle forces was used to quantify the degree of co‐contraction present. Co‐contraction was largely dependent on the direction of exertion and relatively less dependent on the subject or the rate of exertion. Co‐contractions were estimated to contribute approximately 16–19% to the sum of muscle forces at a lumbar cross section during attempted extension of the trunk. Estimated co‐contractions during attempted lateral bending and axial twisting were two to three times greater, which demonstrates that co‐contraction is a major determinant of spinal loading in these tasks. This analysis suggests that substantial contractions of lumbar muscles, especially during asymmetric exertions, are used for reasons other than equilibrating moments at the L3‐L4 level.
Chondrocyte deformation and local tissue strain in articular cartilage: A confocal microscopy study
Authors: Guilak Farshid , Ratcliffe Anthony , Mow Van C. 
Published: February 2005

AbstractIt is well accepted that mechanical forces can modulate the metabolic activity of chondrocytes, although the specific mechanisms of mechanical signal transduction in articular cartilage are still unknown. One proposed pathway through which chondrocytes may perceive changes in their mechanical environment is directly through cellular deformation. An important step toward understanding the role of chondrocyte deformation in signal transduction is to determine the changes in the shape and volume of chondrocytes during applied compression of the tissue. Recently, a technique was developed for quantitative morphometry of viable chondrocytes within the extracellular matrix using three‐dimensional confocal scanning laser microscopy. In the present study, this method was used to quantify changes in chondrocyte morphology and local tissue deformation in the surface, middle, and deep zones in explants of canine articular cartilage subjected to physiological levels of matrix deformation. The results indicated that at 15% surface‐to‐surface equilibrium strain in the tissue, a similar magnitude of local tissue strain occurs in the middle and deep zones. In the surface zone, local strains of 19% were observed, indicating that the compressive stiffness of the surface zone is significantly less than that of the middle and deep zones. With this degree of tissue deformation, significant decreases in cellular height of 26, 19, and 20% and in cell volume of 22, 16, and 17% were observed in the surface, middle, and deep zones, respectively. The deformation of chondrocytes in the surface zone was anisotropic, with significant lateral expansion occurring in the direction perpendicular to the local split‐line pattern. When compression was removed, there was complete recovery of cellular morphology in all cases. These observations support the hypothesis that deformation of chondrocytes or a change in their volume may occur during in vivo joint loading and may have a role in the mechanical signal transduction pathway of articular cartilage.
Comparative study of the size and shape of human anterior and posterior cruciate ligaments
Authors: Harner C. D. , Livesay G. A. , Kashiwaguchi S. , Fujie H. , Choi N. Y. , Woo S. L.‐Y. 
Published: February 2005

AbstractAs an important step toward determination of the function of cruciate ligaments, the cross‐sectional shapes and areas of the anterior cruciate, posterior cruciate, and meniscofemoral ligaments were evaluated in situ within the same knee with use of a laser micrometer system. Measurements were made in eight human cadaveric knees at five levels along the midsubstance of each ligament, with the knee at 0°, 30°, 60°, and 90° of flexion. The posterior cruciate ligament was found to be widest in the medial‐lateral direction, whereas the anterior cruciate ligament usually was larger in the anterior‐posterior direction. The cross‐sectional shapes of the anterior cruciate ligament generally were noted to be more circular along the entire midsubstance than were those of the posterior cruciate ligament. In contrast, the cross‐sectional shapes of the posterior cruciate ligament were more circular near the tibia, becoming progressively more elongated toward the femur. The meniscofemoral ligaments were more circular than the cruciate ligaments, with an occasional medial‐lateral widening similar to that of the posterior cruciate ligament. The cross‐sectional area of both the cruciate ligaments changed along the length of the midsubstance, with the anterior cruciate ligament becoming slightly larger distally and the posterior cruciate ligament enlarging proximally. The angle of flexion of the knee was not found to have a significant effect on the cross‐sectional areas of the ligaments but was noted to alter the cross‐sectional shapes. Using within‐specimen comparisons, the cross‐sectional area of the posterior cruciate ligament was found to be approximately 1.5 times larger than that of the anterior cruciate ligament at the proximal and midsubstance levels but was only 1.2 times larger at the most distal level. The total cross‐sectional area of the meniscofemoral ligaments was approximately 22% that of the posterior cruciate ligament.
Endochondral resorption of chick sterna in culture
Authors: Gibson Gary J. , Lin Dan Li , Schaffler Mitchell B. , Kimura James H. 
Published: February 2005

AbstractEndochondral resorption is most clearly recognized at the metaphyseal interface of the growth plate with the adjacent vasculature: however, apparently identical processes of endochondral resorption are seen in sites of primary and secondary ossification of the cartilaginous anlage of bones and in ossifying fracture callus. Recent evidence of the expression of the hypertrophic phenotype in osteoarthrotic articular cartilage suggests that endochondral resorption also may be a factor in the loss of articular cartilage in this condition. To investigate the mechanism of endochondral resorption, a model culture system was developed and characterized. The two primary centers of ossification with surrounding cartilage were dissected from embryonic chick sterna prior to (18‐day‐old embryos) or after (20‐day‐old embryos) the initiation of resorption. They were cultured either in plastic culture dishes or on chorioallantoic membranes, and resorption was detected by analysis of the loss of types II and X collagen and by histological characterization. Only sterna showing active resorption in vivo were resorbed when cultured on chorioallantoic membrane. The histological appearance of the resorption site and the specificity of resorption to the primary ossification center, seen from both the analysis of loss of collagen and histological observation, suggested that the resorption of sterna cultured on chorioallantoic membrane was similar to that observed in vivo. These studies further indicated that both vascular cells and viable chondrocytes were required for resorption. Susceptibility to resorption could be induced in resistant primary ossification centers by prior culture in the absence of vascular cells, and it is suggested that it results from the accumulation of resorption‐susceptible cells and matrix as a result of continued chondrocyte development.
Effect of tissue culture storage on the in vivo survival of canine osteochondral allografts
Authors: Oates K. M. , Chen A. C. , Young E. P. , Kwan M. K. , Amiel D. , Convery F. R. 
Published: February 2005

AbstractIn vitro studies in our laboratory have shown that the biomechanical and biochemical characteristics of osteochondral grafts can be preserved for as long as 28 days under tissue culture conditions. This study represents an attempt to extend these results to an in vivo model. In adult mongrel dogs, either an autograft, a fresh allograft, or a stored allograft was placed in a standardized defect on the weight‐bearing surface of the medial femoral condyle. The stored grafts were kept at 4°C in tissue culture medium for 14 days prior to implantation. The animals were killed at 12 weeks. Cartilage from the contralateral knee served as a control. The modulus and permeability of the cartilage were assessed with confined compression creep tests. The collagen and glycosaminoglycan contents were measured, and the cartilage was analyzed histologically with hematoxylin and eosin and safranin O stains. Grossly, the cartilage appeared viable at harvest. The histologic results were similar in the treatment groups, with the same spectrum of mild degenerative changes being noted in each group. The glycosaminoglycan content was significantly less in the autograft group than in its control group and than in the fresh allograft group. The glycosaminoglycan content did not differ significantly between fresh and stored allografts. The collagen content, modulus, and permeability did not differ either between experimental and control groups or between graft types. Our results support the conclusion that osteochondral allografts can be stored for as many as 14 days without significantly affecting the results of the procedure.
Tensile properties of the supraspinatus tendon
Authors: Itoi Eiji , Berglund Lawrence J. , Grabowski John J. , Schultz Fredrick M. , Growney Eric S. , Morrey Bernard F. , An Kai‐Nan 
Published: February 2005

AbstractThe tensile properties of the supraspinatus tendon were investigated in 11 shoulders from fresh cadavers. The tendon was divided into three longitudinal strips: anterior, middle, and posterior. Each specimen was mounted on a materials testing machine, with four fluorescent markers placed on both surfaces of the tendon strip. The positions of these markers were recorded during the test by two synchronized video cameras. Load‐deformation and strain curves were determined, and the stress‐strain curve, strength, and modulus of elasticity were calculated. The posterior strip was thinner in cross section than the others (p = 0.0355). The ultimate load and ultimate stress were significantly greater in the anterior strip (16.5 ±7.1 MPa) than in the middle (6.0 ± 2.6 MPa) and posterior (4.1 ± 1.3 MPa) strips (p < 0.0001). The modulus of elasticity also was significantly greater in the anterior strip (p < 0.0001), but there was no significant difference between the superficial and deep surfaces. It is concluded that the anterior portion of the supraspinatus tendon is mechanically stronger than the other portions, and it seems to perform the main functional role of the tendon.
Biomechanical analysis of the ankle anterior drawer test for anterior talofibular ligament injuries
Authors: Tohyama Harukazu , Beynnon Bruce D. , Renström Per A. , Theis Maureen J. , Fleming Braden C. , Pope Malcolm H. 
Published: February 2005

AbstractThe effect of sectioning the anterior talofibular ligament on the load‐displacemnt behavior of the ankle was evaluated in vitro during the anterior drawer test using the flexibility approach. Controlled forces were applied across the ankle joint in the anterior‐posterior direction, and the resulting displacements were measured at four flexion angles (10° of dorsiflexion, neutral, and 10° and 20° of plantar flexion). The anterior talofibular ligament then was sectioned, and the anterior‐posterior loadings were repeated at the four flexion angles. Two parameters were developed to describe the nonlinear load‐displacemnt response of the ankle joint: neutral zone laxity (joint displacement between ± 2.5 N) and flexibility (a measure of the nonlinear load‐displacement response of the ankle between 10 and 50 N of anterior drawer loading). After sectioning the anterior talofibular ligament, significant increases in neutral zone laxity were observed at all angles of ankle flexion. The largest increases in neutral zone laxity were found with the ankle in 10° of plantar flexion (76.3% increase) and 20° of plantar flexion (89.7% increase). After sectioning the ligament, a significant increase (19.3%) in flexibility of the ankle was observed at 10° of dorsiflexion, but no change in flexibility was observed with the ankle in the neutral and plantar flexed positions. These findings indicate that anterior drawer testing of the anterior talofibular ligament‐deficient ankle between 10° and 20° of plantar flexion results in the largest increase in neutral zone laxity compared with the normal ankle with intact ligaments. They also suggest that an excessive magnitude of force during clinical application of the anterior drawer examination may not be needed to diagnose disruption of the anterior talofibular ligament.
Proliferative and phenotypic responses of bone‐like cells to mechanical deformation
Authors: Stanford C. M. , Morcuende J. A. , Brand R. A. 
Published: February 2005

AbstractLimited in vivo and in vitro experiments suggest that bone and bone‐like cells respond to mechanical signals in a trigger‐like rather than a dose‐response fashion; i.e., they fail to respond until they have been stimulated with some given number of cycles of loading, and then once they respond, additional cycles produce little or no effect. To explore this notion, rat calvaria‐derived osteoblast‐like cells and the cell line MC3T3‐E1 were plated at a high cell density (5,000 cells/mm2) on silicone membranes coated with type‐I collagen and were allowed to attach for 24 hours. The membranes then were exposed to vacuum pressure (−1 kPa, 0.5 Hz) on a daily basis, and cultures were assayed every 2 days for 2 weeks. The proliferation of nontransformed cells increased 7‐fold with as few as four daily cycles but not with one cycle per day. Furthermore, 1,800 cycles of vacuum did not result in a greater response than four cycles per day. We observed inverse phenotypic responses: the expression of osteocalcin was depressed compared with controls in the cultures of osteoblast‐like cells that were strained with as few as four cycles per day. Alkaline phosphatase activity was depressed in the cultures of both the osteoblast‐like cells and the MC3T3‐E1 cells exposed to low vacuum pressures (−1 kPa) with four daily cycles of vacuum pressure. Increasing the vacuum magnitude did not affect the occurrence of a “trigger response” between one and four cycles of vacuum application. Bone‐like cells in vitro appear to exhibit trigger‐response behavior analogous to that seen in bone in vivo; the phenotypic response occurs in the opposite direction from the proliferative response.
Time‐dependent changes in the response of cartilage to static compression suggest interstitial pH is not the only signaling mechanism
Authors: Boustany Nada N. , Gray Martha L. , Black Ann C. , Hunziker Ernst B. 
Published: February 2005

AbstractThe goal of the present study was to reexamine the role of interstitial pH in regulating the biosynthetic rate in cartilage tissue by addressing two research questions: (a) Do small, short‐term changes in interstitial pH, induced independently by two different mechanisms (namely, by controlling the pH of the medium or by mechanical compression), result in biosynthetic rates commensurate with those expected from the “natural” relationship between interstitial pH and biosynthesis? and (b) Are the effects of changes in the pH of the medium or in compression the same for short‐term (14‐hour) and long‐term (60‐hour) exposures? Biosynthetic rates were estimated from incorporation of sulfate and proline into explants of bovine epiphyseal cartilage during the final 14 hours of culture. These rates decreased with decreasing pH of the medium, with increasing compression, and with decreasing native glycosaminoglycan content; or, expressed in terms of interstitial pH, acidification induced by compression or by lowering the pH of the medium resulted in a decreased biosynthetic rate, whereas interstitial acidification effected by increasing glycosaminoglycan content enhanced it. When the time for which tissue was exposed to changes in the pH of the medium was increased from 14 to 60 hours, the relationship between the biosynthetic rate and the pH remained constant whereas the relationship between the biosynthetic rate and compression was reversed. These data suggest that the transduction mechanisms underlying the response to pH of the medium and compression differ and that some adaptation or stimulation by modest levels of compression can occur with longer exposures. Interstitial pH is not the sole determinant of biosynthesis, and it cannot really account for the long‐term response of cartilage tissue to static compression.
Primary osteoarthrosis in guinea pigs: A stereological study
Authors: de Bri Edin , Reinholt Finn P. , Svensson Olle 
Published: February 2005

AbstractVolumes and surfaces of articular cartilage and subchondral bone of the proximal tibial epiphysis were measured by unbiased stereological methods on the light microscopic level in groups of 6, 12, and 30‐month‐old (adult, middle‐aged, and old) guinea pigs with primary osteoarthrosis. At 12 months, structural changes similar to those of human osteoarthrosis had developed, predominantly on the central medial condyle, which was not covered with meniscus. The lateral condyle was virtually unaffected; this allowed separate analysis of age‐related and disease‐related changes. Fibrillation and destruction of cartilage was accompanied by a simultaneous increase of the volume of both cartilage (66%) and subchondral bone (50%). The epiphyseal volume increased by 27% at 12 months, predominantly on the medial (osteoarthrotic) condyle, whereas the volume of the lateral condyle increased only in the oldest age group; this indicated that the joint has a potential for growth and remodeling. Joint growth has been suggested as a pathogenic factor in osteoarthrosis. The 65% increase in thickness noted in subchondral bone was a further indication of the importance of proliferative bone changes in early osteoarthrosis. The low variability of osteoarthrosis in this animal model makes it possible to obtain stable quantitative data from relatively small groups of animals.
Arthritis not immobilization causes bone loss in the carrageenan injection model of inflammatory arthritis
Authors: Bogoch E. R. , Moran E. , Crowe S. , Fornasier V. 
Published: February 2005

AbstractOne suggested cause of the high turnover osteopenia of experimental inflammatory arthritis is disuse of affected joints. To compare the influence of immobilization or disuse, or both, with that of inflammatory arthritis on bone turnover, rabbits were placed into four groups. In group 1, arthritis was induced in the right knee by seven intra‐articular injections of 1% carrageenan, over 49 days; in group 2, a plaster cast was applied to immobilize the right hindlimb in flexion; in group 3, arthritis was induced and the hindlimb was immobilized; and in group 4, nothing was done (control). The fluorescent label calcein was administered in drinking water (0.05%) ad libitum to all groups on days 22‐36. On day 49, specimens were prepared for analysis of bone volume and new bone volume at a near site (right femur) and at remote sites (contralateral femur and ipsilateral humerus). The data were analysed by multiple regression and Bonferroni tests. In group 1, new bone volume was three times higher than in group 2 or 4 (p < 0.05 for each comparison); this indicated increased bone remodeling in the right femur. This contrasted with group 2, in which neither index of bone remodeling was changed. The combination of immobilization with arthritis resulted in more intense osseous effects of inflammatory arthritis, with a one‐quarter decrease in bone volume (group 3,30.99 ± 2.50; group 4, 42.07 ± 2.38, p < 0.05), as well as a 4‐fold increase in new bone volume (p < 0.001) compared with group 1. A possible systemic effect in this model of arthritis was evidenced by increased new bone volume in the contralateral femur in the group that had arthritis and immobilization (4.66 ± 0.57, p < 0.05).