bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of the inflammatory response to particulate polymethylmethacrylate debris with and without barium sulfate
Authors: Lazarus M. D. , Cuckler J. M. , Schumacher H. R. , Ducheyne P. , Baker D. G. 
Published: February 2005

AbstractParticulate polymethylmethacrylate debris has been implicated in the inflammatory response observed surrounding loosened cemented implants. The rat subcutaneous pouch model and the Howie implant model (used to study bone resorption) were used to quantify the response to mechanically produced endotoxin‐free polymethylmethacrylate debris with and without 10% (wt/vol) BaSO4. In the rat subcutaneous pouch model, the inflammatory response to polymethylmethacrylate particles containing BaSO4 was greater than the response to plain polymethylmethacrylate particles of similar size. Increased inflammation was measured by leukocyte counts and levels of prostaglandin E2, tumor necrosis factor, and neutral metalloprotease. In addition, particulate polymethylmethacrylate with BaSO4 caused significantly greater bone resorption in the Howie model than did particulate plain polymethylmethacrylate. In in vitro studies, particulate polymethylmethacrylate with BaSO4 stimulated more prostaglandin E2, neutral metalloprotease, and tumor necrosis factor from human monocytes in culture and stimulated greater proliferation of synovial cells than did particulate plain polymethylmethacrylate. The presence of BaSO4 appears to significantly intensify the inflammatory response to polymethylmethacrylate debris.
Effects of thapsigargin, an intracellular calcium‐mobilizing agent, on synthesis and secretion of cartilage collagen and proteoglycan
Authors: Clark Charles C. , Iannotti Joseph P. , Misra Sanjay , Richards Charlotte F. 
Published: February 2005

AbstractThe calcium‐mobilizing agents thapsigargin and 2.5‐di‐(tert‐butyl)‐1,4‐benzo‐hydroquinone were shown to markedly elevate the intracellular calcium concentration of chick embryo chondrocytes in a dose‐dependent manner. Under these conditions, the metabolism of macromolecules was variably affected. The synthesis and secretion of protein in general, and of collagen in particular, were significantly inhibited; in contrast, proteoglycan synthesis (but not glycosaminoglycan synthesis) was inhibited, whereas secretion was unaffected. Flunarizine, which prevented the thapsigargin‐induced intracellular calcium elevation, and EGTA, which caused only a transient thapsigargin‐induced intracellulr calcium elevation, did not reverse these alterations. It was concluded, therefore, that the observed effects of thapsigargin and 2,5‐di‐(tert‐butyl)‐1,4‐benzohydroquinone on chondrocyte macromolecule metabolism were not related to the ability of these drugs to increase the cytosolic free calcium concentration but may have been due to the specific depletion of the calcium sequestered in the endoplasmic reticulum. The differential effect of these drugs on protein and proteoglycan secretion suggests that the intracellular trafficking of these two classes of macromolecules may be controlled independently.
Response of three murine macrophage populations to particulate debris: Bone resorption in organ cultures
Authors: Glant Tibor T. , Jacobs Joshua J. 
Published: February 2005

AbstractParticulate wear debris from bone cement or prosthetic components can stimulate macrophages to cause bone resorption. We compared the effect of particle composition (titanium and polymethylmethacrylate as inherent components of prosthetic materials or bone cement and polystyrene as a reference material) on the secretion of interleukin‐1 and prostaglandin E2 by periotoneal macrophages and monocyte/macrophage cell lines (P388D1 and IC‐21) and on the bone‐resorbing activity of conditioned medium harvested from these particle‐challenged macrophages. Titanium particles (1–3 μm) in peritoneal macrophage cultures exhibited significantly enhanced bone‐resorbing activity measured as 45Ca release, whereas polymethylmethacrylate and polystyrene exhibited this effect to a greater extent in the P388D1 and IC‐21 monocyte/macrophage cultures. Although exogenous prostaglandin E2 and recombinant human interleukin‐1 could significantly increase the 45Ca release and indomethacin significantly reduced both the spontaneous calcium efflux and active 45Ca release from calvarial bones labeled in vivo, the levels of interleukin‐1 and prostaglandin E2, alone or together, did not always correlate with the bone‐resorbing activity of conditioned media. Thus, the actual levels of potent bone‐resorbing agents (prostaglandin E2 and interleukin‐1) measured in conditioned tissue culture media did not necessarily reflect the bone‐resorbing capability. An important result of this study is that different macrophage populations may respond differently to the same microenvironmental signal, which in our investigation was particulate wear debris of differing composition and size.
Hisotological and radiographic determination of the age of physeal closure of the distal femur, proximal tibia, and proximal fibula of the New Zealand white rabbit
Authors: Kaweblum Moises , Aguilar Maria Del Carmen , Blancas Eduardo , Kaweblum Jaime , Lehman Wallace B. , Grant Alfred D. , Strongwater Allan M. 
Published: February 2005

AbstractA longitudinal study was performed in a series of 124 New Zealand White rabbits to determine the radiographic versus the histologic age of closure of the growth plates of the distal femur, proximal tibia, and proximal fibula. Periodic assessment was made by standard radiographs and histological studies. Histologically, growth plates in the distal femur closed at 19–24 weeks; growth plates in the proximal tibia, at 25–32 weeks; and growth plates in the proximal fibula, at 26–32 weeks. Radiographically, evidence of closure of growth plates in the distal femur occurred at 20–23 weeks; in the proximal tibia, at 22–27 weeks; and in the proximal fibula, at 23–31 weeks. A discrepancy in age between radiographic and histologic closure of the growth plate occurred in 3.6% of the femora, 10.9% of the tibias, and 16% of the fibulas.
Demonstration of HLA and ABH Antigens in Fresh and Frozen Human Menisci by Immunohistochemistry
Authors: Khoury Miguel A. , Goldberg Victor M. , Stevenson Sharon 
Published: February 2005

AbstractThe expression of HLA and ABH antigens in fresh, frozen, and twice‐frozen normal human meniscal tissue was evaluated with use of immunohistochemistry. A generalized expression of Class‐I and Class‐II HLA antigens was found in the endothelial and synovial cells of all three forms of tissue. Fibrochondrocytes were Class‐I positive and Class‐II negative. ABH antigens were expressed by endothelial cells in relationship to the blood group of the patient. Freezing preserved most of the HLA and ABH molecular structure. Although the normal meniscus consists of a relatively few chondrocytes embedded in an extracellular matrix, it also contains Class‐II and ABH‐positive endothelial cells and Class‐II‐positive synovial cells. These antigens are present at the moment of transplantation and could evoke an immune response in the host that would modulate the results of meniscal allografting.
Method for establishing and measuring in vivo forces in an anterior cruciate ligament composite graft: Response to differing levels of load sharing in a goat model
Authors: Lewis Jack L. , Poff Bradley C. , Smith Joel J. , Lindquist Conrad , Engebretsen Lars , Lew William D. 
Published: February 2005

AbstractIn order to determine the appropriate load history for optimal remodeling of an anterior cruciate ligament graft, methods for establishing and measuring graft forces in vivo are required. Our objectives with this study were to (a) develop a method in which the graft force due to an external load could be set to a preselected value in a living animal, (b) show that this force could be maintained after fixation, and (c) determine what happens to the forces after the animal has functioned for as long as 2 weeks postoperatively, when differing levels of load sharing between the segments had been set at surgery. The anterior cruciate ligament was reconstructed in 12 goats with use of a bone‐patellar tendon‐bone graft and a synthetic augmentation device. The forces in the graft segments were established, at the time of surgical fixation, with use of a force‐setting technique. In five animals, the tendon segment was set to carry 90% of the total graft force; in the remaining seven animals, the augmentation segment was set to share 90% of the total graft force. Graft forces were measured, with the use of buckle transducers mounted extra‐articularly over the anterior tibia, under a 67 N anterior tibial load at 60° of knee flexion before and after fixation and at 2 weeks postoperatively. When the tendon was the high force‐carrying member, the force in the tendon decreased by an average of 25% during the 2 weeks after surgical fixation, while the force in the augmentation segment showed a significant increase of 111%. When the augmentation segment was the high force‐carrying segment, the force in that segment decreased by an average of 10% during the 2 weeks and the tendon force increased by 47%. These data suggest that when the tendon was set to carry high force, it may have stretched, due to biological changes in the tissue, and that the augmentation segment was not as greatly affected over the 2 postoperative weeks when it was set to carry most of the total load. Because of the frictional effects of the graft segments passing around the osseous contours of the anterior tibia and the fact that the calibrations of the buckle transducer from surgery were used to reduce the data on force at 2 weeks postoperatively, there are uncertainties related to the measured graft segment forces in this study. However, if the animals had been killed and the buckle transducers calibrated immediately after the test at 2 weeks, these uncertainties would not exist.
Estimation of material properties in the equine metacarpus with use of quantitative computed tomography
Authors: Les C. M. , Keyak J. H. , Stover S. M. , Taylor K. T. , Kaneps A. J. 
Published: February 2005

AbstractThe purpose of this study was to investigate the relationships between data obtained from quantitative computed tomography and mechanical properties in the equine metacarpus, as measured in vitro in bone specimens. Three hundred and fifty‐five bone specimens from the metacarpi of 10 horses were machined into right cylinders aligned with the long axis of the bone. A computed tomographic scan of the specimens, along with a Cann‐Genant K2HPO4 calibration standard, was obtained. The specimens then were compressed to failure, and the elastic modulus, yield stress, yield strain, strain energy density at yield, ultimate stress, ultimate strain, and strain energy density at ultimate failure were calculated. The specimens were dried and ashed. Quantitative computed tomography‐derived K2HPO4 equivalent density proved to be an excellent estimator (r2 > 0.9) of elastic modulus, yield stress, ultimate stress, wet density, dry density, and ash density; a moderately good estimator (0.4 < r2 < 0.9) of strain energy density at yield and at ultimate failure; and a poor estimator (r2 < 0.2) of yield strain and ultimate strain. It was concluded that the relationships between quantitative computed tomography data and mechanical properties of the equine metacarpus were strong enough to justify the use of these data in automated finite element modeling.
Ion resonance electromagnetic field stimulation of fracture healing in rabbits with a fibular ostectomy
Authors: Deibert Mark C. , Mcleod Bruce R. , Smith Stephen D. , Liboff Abraham R. 
Published: February 2005

AbstractRabbits with a fibular ostectomy were exposed for 28 days to magenetic fields that satsfied the ion resonance conditions for calcium or magnesium. The rabbits were exposed to whole body treatment for 1/2 hour, 3 hours, or 24 hours per day. The fibulae from the experimental and control animalas were removed surgically and were subjected to force‐deflection testing to establish the stiffness of the healed fracture. The fibulae from the rabbits exposed to the ion resonance magnetic fields were found to be 55‐299% (p < 0.01) more robust than the fibulae from the control animals.
Effect of static load on matrix synthesis rates in the intervertebral disc measured in vitro by a new perfusion technique
Authors: Ohshima Hiroshi , Urban J. P. G. , Bergel D. H. 
Published: February 2005

AbstractThe effect of static loading on matrix synthesis was measured in intact bovine coccygeal discs. The discs were maintained at 37°C in a humid atmosphere and were perfused across their upper and lower surfaces for as long as 8 hours with media containing radioisotopes (3H‐proline and 35S‐sulphate) via porous filter disks embedded in Perspex (Plexiglas) holders. Static loads were applied to the disc with use of weights. The activity of free, nonincorporated isotope in the centre of the disc was monitored continuously with a microdialysis probe. Incorporated tracer in different regions of the disc was determined at the end of each experiment from the activity of the nondialysable tracer. Free tracer activity rose steeply over the first 3–4 hours of perfusion, as tracer diffused into the disc, and reached a steady value after 5–6 hours, as expected from diffusion theory. The rate of tracer incorporation estimated from the integrated value of free tracer concentration was constant for as long as 8 hours. Incorporation rates varied across the disc: the highest rates were in the inner layer of the annulus fibrosus, and the lowest rates were in the outer layer of the annulus. The rates for both 35S‐sulphate and 3H‐proline varied with load. The rates were lowest in the nucleus pulposus and the inner layer of the annulus fibrosus with a 0.5 kg load, and they almost doubled as the load was increased to 5–10 kg. Heavier loads (15 kg) led to a decrease in incorporation. Hydration of the disc also varied with load; hydration decreased as load increased and was maintained near in vivo values with 5–10 kg of load (0.13–0.26 MN/m2). The effect of load on incorporation rates in the disc is compatible with the suggestion that rates are at a maximum at in vivo hydrations and decrease if the hydration decreases or if the disc swells.
Autogenous flexor tendon grafts: Fibroblast activity and matrix remodeling in dogs
Authors: Abrahamsson Sven‐Olof , Gelberman Richard H. , Amiel David , Winterton Paul , Harwood Fred 
Published: February 2005

AbstractTo investigate rates of cellular proliferation and matrix turnover in autogenous flexor tendon grafts, hindlimb intrasynovial (flexor digitorum profundus) and extrasynovial (peroneus longus) tendons were placed within the synovial sheaths of the medial and lateral forepaw digits of 18 dogs and treated with controlled early passive motion. After the dogs had been killed, short‐term culture and labeling in vitro were utilized to determine rates of DNA, proteoglycan, collagen, and noncollagen protein synthesis. Schiff base covalent collagen crosslink concentrations and total collagen and protein content also were evaluated at intervals through 6 weeks. Tendon grafts of extrasynovial origin showed greater rates of DNA synthesis and significantly elevated levels of proteoglycan, collagen, and noncollagen protein synthesis and Schiff base covalent collagen crosslink concentrations (dihydroxylysinonorleucine) compared with intrasynovial tendon grafts. It was not clear to what extent the increased activity in the extrasynovial graft was due to actual differences between the intrasynovial and extrasynovial tendons or to the responses of the connective tissue surrounding the extrasynovial tendon graft. Since both types of grafts demonstrated similar unaltered levels of collagen and protein content over time, these data suggest greater rates of matrix turnover in tendon grafts of extrasynovial origin than in those of intrasynovial origin. Coupled with previous findings showing increased cellular proliferation in extrasynovial tendon grafts, these data indicate that the process of translation to an intrasynovial environment necessitates a more active process of soft‐tissue repair and remodeling when extrasynovial donor tendons are used.
Preserving plantar flexion strength after surgical treatment for contracture of the triceps surae: A computer simulation study
Authors: Delp Scott L. , Statler Kimberly , Carroll Norris C. 
Published: February 2005

AbstractContractures of the triceps surae commonly are treated by surgical lengthening of the gastrocnemius aponeurosis or the Achilles tendon. Although these procedures generally relieve contractures, patients sometimes are left with dramatically decreased plantar flexion strength (i.e., decreased capacity to generate plantar flexion moment). The purpose of this study was to examine the trade‐off between restoring range of motion and maintaining plantar flexion strength after surgical treatment for contracture of the triceps surae. A computer model representing the normal moment‐generating characteristics of the triceps surae was altered to represent two conditions: isolated contracture of the gastrocnemius and contracture of both the gastrocnemius and the soleus. The effects of lengthening the gastrocnemius aponeurosis and the Achilles tendon were simulated for each condition. The simulations showed that nearly normal moment‐generating characteristics could be restored when isolated gastrocnemius contracture was treated with lengthening of the gastrocnemius aponeurosis. However, when isolated gastrocnemius contracture was treated with lengthening of the Achilles tendon, the moment‐generating capacity of the plantar flexors decreased greatly. This suggests that lengthening of the Achilles tendon should be avoided in persons with isolated gastrocnemius contracture. Our simulations also suggest that neither lengthening of the gastrocnemius aponeurosis nor lengthening of the Achilles tendon by itself is an effective treatment for combined contracture of the gastrocnemius and soleus. Lengthening the gastrocnemius aponeurosis did not decrease the excessive passive moment developed by the contracted soleus. Lengthening the Achilles tendon restored the normal passive range of motion but substantially decreased the active force‐generating capacity of the muscles. Our simulations indicate that independent lengthening of the contracted gastrocnemius and soleus, rather than lengthening of their common tendon, accounts for differences in the architecture of these muscles and may be a more effective means to restore range of motion and maintain plantar flexion strength when combined contracture of the gastrocnemius and soleus is present.
Patellar tracking measurement in the normal knee
Authors: Nagamine Ryuji , Otani Takuya , White Stephen E. , McCarthy Daniel S. , Whiteside Leo A. 
Published: February 2005

AbstractEleven fresh frozen cadaveric knee specimens were mounted in a knee kinematics test device, and normal patellar movements were evaluated with use of an external device for direct measurement of patellar movements. The effects of four different measurement conditions were assessed through alteration of one condition and determination of its effect on patellar kinematics with the use of six specimens. The four conditions included (a) change of the measuring axis from an axis parallel to the central axis of the femur (femoral axis) to one parallel to the central axis of the tibia (tibial axis), (b) rotation of the femoral axis internally 6°, (c) change of the direction of the quadriceps force from parallel to the mechanical line of the lower extremity to a direction parallel to the femoral shaft, and (d) increase of the magnitude of the quadriceps force from 111 to 500 N. During knee flexion, the patella shifted laterally after a slight initial medial shift, tilted laterally from midflexion to 90°, and gradually rotated medially. The patellar shift relative to the tibial axis appeared to be more medial than the shift measured relative to the femoral axis; the discrepancy was caused by the valgus position of the tibia relative to the femur. Changing the rotational angle of the femoral axis artifically changed the patellar position. Varying the direction of the quadriceps within the narrow range and increasing the quadriceps force did not affect patellar movements. It is likely that the anatomic configuration of the patella allows the patella to seat in a stable configuration so that it resists moderate changes in the load and direction of the quadriceps. Tibial rotation exerted a major influence on patellar shift and tilt in the early phase of knee flexion: the patella rotated medially when the tibia was externally rotated and rotated laterally when the tibia was internally rotated. These results indicate that the patella may be unstable in the first phase of knee flexion when the tibia is rotated.
Regional mitogenic response of the meniscus to platelet‐derived growth factor (PDGF‐AB)
Authors: Spindler K. P. , Mayes C. E. , Miller R. R. , Imro A. K. , Davidson J. M. 
Published: February 2005

AbstractSince meniscal healing is region‐specific, we studied the regional (peripheral compared with central) response of meniscal explants to human, recombinant platelet‐derived growth factor‐AB. Mensical explants from the hindlimbs of both knees of mature sheep were sectioned and were cultured with variable doses of human, recombinant platelet‐derived growth factor‐AB, and incorporation of [3H]‐thymidine was measured. The mitogenic response was measured at different times in culture (48 or 96 hours) and by location (lateral or medial). In the absence of the growth factor, the peripheral third of both menisci incorporated 10‐fold more [3H]‐thymidine on a weight basis than did the central two‐thirds. Cellularity was equivalent in the two regions. Doses of less than 100 ng/ml of growth factor produced either no stimulation or a variable response. A dose of 100 ng/ml resulted in consistent, significant (p < 0.05) stimulation in all groups in the peripheral region, and a dose of 200 ng/ml provided more than a 2.5‐fold increase. Multiple‐factor analysis of variance demonstrated that there were no significant differences between experiments, times in culture, or menisci. The central region did not respond to stimulation with the growth factor at any of the doses tested. These data suggest that regional differences (peripheral compared with central) in responsiveness to human, recombinant platelet‐derived growth factor‐AB may reflect a different level of signal transduction machinery for growth factor receptors and distinct fibrochondrocyte populations. These findings are consistent with the variable healing capcity of the meniscal regions in vivo and suggest a pharmacological means to promote the repair of the peripheral meniscal region.