bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of osmotic water movement in chondrocytes isolated from articular cartilage and applications to cryopreservation
Authors: McGann L. E. , Stevenson M. , Muldrew K. , Schachar N. 
Published: February 2005

AbstractThe ability of chondrocytes to survive conditions encountered during cryopreservation depends on the responses of the cells to the physiochemical changes that result when water is removed from the environment of the cells in the form of ice. Cellular responses are therefore closely related to the osmotic permeability properties of the plasma membrane. In order to optimize the conditions for cryopreservation of chondrocytes, osmotic properties of the chondrocyte membrane were determined from the kinetics of volume change in hypertonic solutions at different temperatures. The hydraulic conductivity of the plasma membrane was 0.305 ± 0.025 μm3/μm2/min/atmosphere at 24°C, with an Arrhenius activation energy of 8.06 kcal/mol. These values are similar to those reported for other cell types, but the osmotically inactive volume of the chondrocytes (0.41 ± 0.04) was significantly higher than for other cells, implying that chondrocytes have a higher dry weight ratio or that they contain a higher proportion of osmotically inactive or bound water. These results were used to calculate the osmotic responses of chondrocytes at low temperatures and to predict that the least damaging cooling rate for isolated chondrocytes in the absence of cryoprotective compounds is 10°C/min. The ultimate goal of this study is the development of an analytical model applicable to the optimization of techniques for cryopreservation of intact cartilage and other tissues.
Moderate running exercise augments glycosaminoglycans and thickness of articular cartilage in the knee joint of young beagle dogs
Authors: Kiviranta Ilkka , Tammi Markku , Jurvelin Jukka , Säämänen Anna‐Marja , Helminen Heikki J. 
Published: February 2005

AbstractThe local influences of physical exercise on thickness and glycosaminoglycan (GAG) content of canine articular cartilage were measured by microspectrophotometry of Safranin O‐ and periodic acid‐Schiff (PAS)‐stained tissue sections. Female Beagle dogs were housed in individual cages (bottom 0.9 × 1.2 m) and divided into runner (n = 6) and control (n = 8) groups. The trainig program started at the age of 15 weeks. During the subsequent 10 weeks, the dogs were accustomed to running on a treadmill inclined 15° uphill. Thereafter, the dogs ran 1 h daily, 5 days a week, at a speed of 4 km/h for 15 weeks. At the age of 40 weeks, the dogs were killed, and the samples for histology were taken from 11 different anatomical locations of the right knee (stifle) joint. The thickness of the uncalcified cartilage increased 19–23% on the lateral condyle and patellar surface of the femur, whereas the enhancement was smaller in other parts of the trained cartilage. The calcified cartilage did not show thickness alterations. Total GAGs were augmented by 28% in the summits on the femoral condyles, more on the medial than lateral side. The increased GAGs appeared to be predominantly chondroitin sulphates and were localized in the intermediate, deep, and even in the calcified zones, whereas the superficial zone did not show changes. There was a concomitant increase of non‐GAG oligosaccharides in the intermediate and deep zones, but not in the calcified cartilage. As judged from the enhanced GAG content and thickness, it is considered that moderate running exercise locally alters the biological properties of young articular cartilage at regions bearing the highest loading surplus.
Hydraulic resistance: A measure of vascular outflow obstruction in osteonecrosis
Authors: Downey Daniel J. , Simkin Peter A. , Lanzer William L. , Matsen Frederick A. 
Published: February 2005

AbstractThis study introduces hydraulic resistance (HR) as a new method to measure intraosseous vascular outflow resistance in the human proximal femur. HR is the standard measure of resistance to fluid flow in porous matrices and is derived from serial pressure/flow determinations. Eighteen hips were studied in 11 patients taken to surgery for core decompression therapy of presumable atraumatic osteonecrosis of the femoral head. HR was much higher in osteonecrotic (174 ± 29 mm Hg min/ml, SE) than in normal human cadaveric femora (14 ± 6) and was also higher in subcapital (253 ± 39) than intertrochanteric sites (78 ± 17). HR correlated highly with baseline intraosseous pressure (r = 0.74, p < 0.001). HR testing is a simple, practical method which quantifies outflow obstruction of the intraosseous circulation. We believe this test will be helpful in the diagnosis of atraumatic osteonecrosis and in the understanding of its underlying pathophysiology.
The influence of different degrees of stiffness of fixation plates on experimental bone healing
Authors: Terjesen Terje , Apalset Kristen 
Published: February 2005

AbstractIn order to throw some light on the controversial issue of the optimal stiffness in fracture fixation, the effects on bone healing of rabbit tibial osteotomies fixed by plates with four different degrees of stiffness were studied. The least stiff plate was made of glass fiber‐reinforced epoxy; the other three were made of stainless steel. The median bending stiffness in vitro of tibial osteotomies fixed with the various plates were 13%, 17%, 61%, and 74%, related to the stifness of intact tibiae. Transverse midshaft unilateral tibial osteotomies were fixed by the various plates, and the animals were killed after 6 weeks. The amount of periosteal callus was inversely related to the stiffness of the plates. A marked trend toward decreased strength and stiffness occurred in tibiae where the most rigid plate was used, compared with the values of those with the less rigid plates. This indicates that the stress‐protecting effect of very stiff plates begins early in the healing period and is pronounced even at 6 weeks and that a steel plate of lower stiffness is more appropriate for bone healing. However, too flexible plates involve increased risk of redislocation and mechanical failure.
Osteogenesis in rats with an inductive bovine composite
Authors: Nathan Ranga M. , Bentz Hanne , Armstrong Rosa M. , Piez Karl A. , Smestad Thomas L. , Ellingsworth Larry R. , McPherson John M. , Seyedin Saeid M. 
Published: February 2005

AbstractSubcutaneous (S.C.) implantation of allogeneic demineralized bone matrix in rats results in endochondral bone formation. In contrast, implants of bovine demineralized bone matrix in rat S.C. tissue show inconsistent cartilage and bone formation, presumably due to an intense inflammatory reaction at the implant site. To overcome this response, a partially purified bone inducing extract was prepared from bovine bone by a series of steps that included demineralization, guanidine/HCI extraction, gel filtration, and cation exchange chromatography. To develop a carrier, the inactive guanidine/HCI‐extracted matrix was then trypsinized to remove the inflammatory and immunogenic components, thus yielding a predominantly collagenous matrix. Bovine composites were prepared by combining different amounts of the bone inducing extract with a carrier that consisted of the trypsinized bone matrix and purified soluble bovine dermal collagen. Subcutaneous implantation of the composite preparation resulted in dose‐dependent endochondral bone formation in rats. The inductive activity and the low‐level inflammatory response were comparable to allogeneic implants.
Canine osteoarthritis: Effects of endogenous neutral metalloproteoglycanases on articular cartilage proteoglycans
Authors: Pelletier J. P. , Martel‐Pelletier J. , Malemud C. J. 
Published: February 2005

AbstractThe aim of this study was to analyze the mechanisms by which neutral metalloproteoglycanases (NMPE) degrade proteoglycans (PGs) in the cartilage of an experimental model of osteoarthritis (OA). We demonstrated that chondrocytes in osteoarthritic cartilage synthesize PGs with the same functional characteristics as those found in normal cartilage. Osteoarthritic cartilage contains NMPE in both active and latent forms. Both forms can degrade newly synthesized and endogenous PG macromolecules, as indicated by the reduced hydrodynamic size found in the two PG populations of osteoarthritic cartilage. PG monomers, derived from the included fraction of Sepharose CL2B chromatography, were unable to form aggregates with hyaluronic acid. Reduction and alkylation showed that PG monomers from osteoarthritic cartilage had a small hydrodynamic size, especially after activation with aminophenylmercuric acetate. No significant differences were observed in the size of the chondroitin sulfate chain when normal cartilage was compared with its osteoarthritic equivalent. These results suggest that the proteolytic degradation of cartilage matrix PGs by NMPE occurs at both the hyaluronate‐binding region and at the chondroitin sulfate‐rich region of the core protein.
Antibiotic release from an experimental biodegradable bone cement
Authors: Gerhart T. N. , Roux R. D. , Horowitz G. , Miller R. L. , Hanff P. , Hayes W. C. 
Published: February 2005

AbstractAn experimental biodegradable bone cement [poly(propylene fumarate)‐methylmethacrylate] (PPF‐MMA) has been compared in vivo with polymethylmethacrylate (PMMA) as a carrier agent for local release of antibiotics. This approach is potentially applicable to the treatment of chronic osteomyelitis where the clinical goal is to achieve sustained high concentrations of antibiotics locally in the infected bone. In our experiments, gentamicin‐ and vancomycin‐impregnated cylindrical PMMA and PPF‐MMA cement specimens were implanted subcutaneously in rats, and blood and wound fluid samples were obtained over a 2‐week period. Antibiotic levels were determined using immunoassays, and microbiologic activity was confirmed with agar diffusion techniques. The biodegradable PPF‐MMA cement achieved and maintained considerably higher wound antibiotic levels than did PMMA cement. Vancomycin levels for the PPF‐MMA cement were greater than 20 times those for the PMMA cement at all sampling times from 24 h to 14 days. For both cements, the serum antibiotic concentrations remained safely below maximum levels recommended for parenteral therapy. Mechanical testing of the PPF‐MMA cement showed that admixture of 3% by weight of antibiotic did not adversely affect material properties. We conclude that this experimental biodegradable bone cement (PPF‐MMA) can be used as a carrier to achieve high sustained local levels and low serum levels of antibiotics. Because it is biodegradable and thus does not require a secondary procedure for removal, it has special potential for use in treatment of chronic osteomyelitis.
Predicting talocalcaneal joint orientations from talocalcaneal/talocrural joint orientations
Authors: Engsberg Jac R. , Grimston Susan K. , Wackwitz John H. 
Published: February 2005

AbstractThe purpose of this investigation was to determine the capacity of talocalcaneal/talocrural joint orientations to predict talocalcaneal (TC) joint orientations. A custom designed orientation‐loading fixture was used to position the calcaneus and shank with six degrees of freedom, and to apply loads in three orthogonal directions. Three reference pins were rigidly mounted in the calcaneus, talus, and shank segments to provide position data in 243 test situations. Test data were fitted to statistical models using analysis of variance. The models were then used to determine the capacity to predict talus positions from shank positions, both with respect to the calcaneus. Results indicated large between and within specimen variation and was attributed to individual joint morphology. It was concluded that (a) eversion‐inversion orientations of the TC/talocrural joint were not always accurate indicators of TC joint orientations. (b) abduction‐adduction orientations of the combined joint had the greatest overall influence on TC orientations (thus, monitoring eversion‐inversion and abduction‐adduction orientations of the combined joint would be more valuable in predicting pronation‐supination positions than monitoring only eversion‐inversion orientations), and (c) foot categories based on TC and TC/talocrural joint morphology should be developed. They would provide more accurate prediction for specimen foot orientations than prediction from overall average values.
Treatment of antigen‐induced arthritis in rabbits with dysprosium‐165–ferric hydroxide macroaggregates
Authors: Zuckerman Joseph D. , Sledge Clement B. , Shortkroff Sonya , Venkatesan Prasanna 
Published: February 2005

AbstractDysprosium‐165–ferric hydroxide macroaggregates (165Dy‐FHMA) was used as an agent of radiation synovectomy in an antigen‐induced arthritis model in New Zealand white rabbits. Animals were killed up to 6 months after treatment. 165Dy‐FHMA was found to have a potent but temporary antiinflammatory effect on synovium for up to 3 months after treatment. Treated knees also showed significant preservation of articular cartilage architecture and proteoglycan content compared with untreated controls, but only during the first 3 months after treatment. In animals killed 3 and 6 months after treatment there were only minimal differences between the treated and untreated knees, indicating that the antiinflammatory effects on synovial tissue and articular cartilage preservation were not sustained.
Gain in mass density of bone following strenuous physical activity
Authors: Leichter Isaac , Simkin Ariel , Margulies Joseph Y. , Bivas Arye , Steinberg Raya , Giladi Michael , Milgrom Charles 
Published: February 2005

AbstractA group of 223 military recruits aged 18–21 years underwent strenuous physical training for a period of 14 weeks. The absolute bone density of the distal tibia in both lower limbs was measured before the training period and at its end. The density was determined by the Compton scattering technique, which has been developed in our laboratory; this method provides the bone mass of all bone constituents per unit volume. The distribution curve of the bone density in both tibiae shifted to higher values at the end of the training period. The mean bone density in the right and left tibia increased significantly by 7.5%. This study indicates that following an intensive physical exercise regime, a significant increase in the mass density of bone can be obtained in young adults within a short period.
The mechanical and morphological properties of bone beneath internal fixation plates of differing rigidity
Authors: Claes L. 
Published: February 2005

AbstractThe internal fixation of diaphyseal fractures by bone plates is a well recognized treatment. The normal physiological stress of bone is reduced by plates that cause a negative balance of bone‐remodeling processes. Many investigators have shown that the degree of stress protection is dependent on the rigidity of the plates. It was the aim of this study to quantify mechanical and morphological changes at different locations in a plated diaphyseal bone as a function of differing plate rigidity. Two types of plates with the same size but different materials were used. The stainless steel plates had a modulus of elasticity and bending stiffness 3.2 times higher than the carbon fiber reinforced carbon plates. Both types of plates were applied to the intact right and left femora of six foxhounds for 6 months. The stiffer stainless steel plates led to a significantly higher bone loss and correspondingly greater loss of mechanical properties. These effects were greatest directly beneath the plate and less with increasing distance from the plate.
The repair of experimentally produced defects in rabbit articular cartilage by autologous chondrocyte transplantation
Authors: Grande Daniel A. , Pitman Mark I. , Peterson Lars , Menche David , Klein Michael 
Published: February 2005

AbstractUsing the knee joints of New Zealand White rabbits, a baseline study was made to determine the intrinsic capability of cartilage for healing defects that do not fracture the subchondral plate. A second experiment examined the effect of autologous chondrocytes grown in vitro on the healing rate of these defects. To determine whether any of the reconstituted cartilage resulted from the chondrocyte graft, a third experiment was conducted involving grafts with chondrocytes that had been labeled prior to grafting with a nuclear tracer. Results were evaluated using both qualitative and quantitative light microscopy. Macroscopic results from grafted specimens displayed a marked decrease in synovitis and other degenerative changes. In defects that had received transplants, a significant amount of cartilage was reconstituted (82%) compared to ungrafted controls (18%). Autoradiography on reconstituted cartilage showed that there were labeled cells incorporated into the repair matrix.
Role of mechanical loading in the progressive ossification of a fracture callus
Authors: Blenman Patricia R. , Carter Dennis R. , Beaupré Gary S. 
Published: February 2005

AbstractThe progressive ossification pattern in a fracture callus was predicted based on a theory that relates the local stimulus for ossification to the tissue mechanical loading history. Two‐dimensional finite element analyses of a fracture callus were considered at three different stages of ossification. The sites of callus ossification represented in the initial model were predicted by previous analyses relating mechanical stress and vascularity to the differentiation of mesenchymal tissue in the early callus. The zones of further ossification, bone bridging, and bone consolidation predicted in the present study were found to be similar to the ossification patterns that have been documented by other researchers. The approach used to predict fracture healing is identical to that of previous studies predicting joint morphogenesis, with the exception that fracture healing requires continuous, articulating skeletal elements.
Energy absorptive properties of human trabecular bone specimens during axial compression
Authors: Linde Frank , Hvid Ivan , Pongsoipetch Buntoeng 
Published: February 2005

AbstractHuman trabecular bone specimens (n = 121) from the proximal tibial epiphysis of nine macroscopically normal cadaver knees were tested nondestructively to a fixed strain (0.6%) for analysis of unloading energy and hysteresis energy followed by a destructive test for analysis of work to failure. All energy properties showed interindividual variation (p < 0.005). There was a strong positive correlation between unloading energy and both stress (r = 0.95) and stiffness (r = 0.89) determined at 0.6% strain. A less strong, but statistically significant, correlation was found between hysteresis energy and stress (r = 0.82) and stiffness (r = 0.76) at 0.6% strain. There was a negative correlation between the loss tangent and stiffness at 0.6% strain (r = −0.40, p < 0.001). Work to failure correlated positively with modulus of elasticity (r = 0.75), ultimate stress (r = 0.92), and ultimate strain (r = 0.51). There was a positive mutual correlation between all energy properties (p < 0.001).
Use of patellar tendon autograft for anterior cruciate ligament reconstruction in the rabbit: A long‐term histologic and biomechanical study
Authors: Ballock R. Tracy , Woo Savio L‐Y. , Lyon Roger M. , Hollis J. Marcus , Akeson Wayne H. 
Published: February 2005

AbstractTo assess the degree of success of anterior cruciate ligament (ACL) replacement using the patellar tendon (PT) autograft, 29 New Zealand white rabbits underwent ACL reconstruction using a medial one‐third PT autograft. The femur–ligament–tibia complexes were evaluated at 0, 6, 30, and 52 weeks postoperatively for gross and histologic appearances and tensile load to failure properties. Grossly, the autografts did not resemble the control ACLs. Histologically, the autografts progressed from being hypercellular with a random collagen fiber bundle organization to having a near normal cellularity with a more parallel collagen fiber bundle pattern. Anteroposterior knee laxity was more than two times that of the control knees 52 weeks after reconstruction. Biomechanically, the PT autografts plateaued at 30 weeks postoperatively. The ultimate load and stiffness were 15 ± 5% and 24 ± 6% of the control ACLs, respectively. At 52 weeks, the appearance of the PT autograft had some general histologic similarities as compared with the native ACL. However, these similarities did not extend to the functional properties of the autograft.
Effect of muscle flap coverage on bone blood flow following devascularization of a segment of tibia: An experimental investigation in the dog
Authors: Richards Robin R. , Schemitsch Emil H. 
Published: February 2005

AbstractSevere tibial fractures may be associated with soft tissue loss, devascularization of cortical bone, and significant morbidity. Local rotational muscle flap coverage is used to obtain coverage of acute open tibial fractures and to treat chronic osteomyelitis of the tibia. The purpose of this study was to determine (a) the longitudinal and cross‐sectional regional blood flow characteristics of the canine tibia and (b) whether a muscle flap was superior to vascularized skin coverage in restoring blood flow to devascularized canine tibial cortex. A 2.5‐cm segment of tibia between two standardized osteotomies was devascularized. The segment was replaced anatomically and stabilized with a plate. The animals were divided into two experimental group: (a) skin coverage (n = 8), and (b) muscle flap coverage (n = 8). Thirty‐one days postoperatively Ce141 microspheres were injected to measure bone blood flow. The tibial diaphysis was divided into proximal, middle (devascularized), and distal segments. The unoperated leg was used as a control. In the control tibiae, the middle segment was less vascular than either the proximal or distal segment and no difference between anterior and posterior cortical blood flow was observed. Blood flow to the devascularized segment of tibia was significantly greater when it was covered with a muscle flap (p < 0.025). The most significant increase in bone blood flow in the muscle flap coverage group versus the skin coverage group occurred in the anterior cortex of the tibia (p < 0.005). This may be clinically important since the soft tissues over the anterior tibia are commonly deficient following open fractures. The rate of osteotomy union was increased in the experimental group with muscle flap coverage (p < 0.05). These findings indicate that muscle flap coverage enhances the restoration of blood flow to devascularized tibial cortex.
Heterotopic osteogenesis in porous ceramics induced by marrow cells
Authors: Ohgushi Hajime , Goldberg Victor M. , Caplan Arnold I. 
Published: February 2005

AbstractWhen untreated porous calcium phosphate ceramics were transplanted into subcutaneous (s.c.) or intramuscular (i.m.) sites, fibrovascular tissue grew in the pore region without evidence of bone formation. However, when these same ceramics were combined with syngeneic marrow cells, osteogenesis was observed inside the pore region of the implanted ceramic. The osteogenesis began on the surface of the pore region at ∼3 weeks postimplantation by a process of intramembranous bone formation, with the de novo bone tissue observed directly interfacing with the ceramic surface. Infrequently, small isolated areas showed cartilage formation with no noticeable endochondral ossification. At 4 weeks postimplantation of the ceramic with marrow cells, the osteogenesis in the ceremic accompanied an observed increase in compressive strength, rigidity, and energy absorption of the ceramic. These results suggest that a combination of porous ceramics and marrow cells may be useful for clinical problems requiring osseous reconstruction.