bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bisphosphonate (pamidronate/APD) prevents arthritis‐induced loss of fracture toughness in the rabbit femoral diaphysis
Authors: Bellingham Catherine M. , Lee J. Michael , Moran Erica L. , Bogoch Earl R. 
Published: February 2005

AbstractPatients with rheumatoid and other inflammatory arthritis have an increased risk for fracture. This study was designed to determine the effect of experimental inflammatory arthritis on the material properties (fracture toughness and shear modulus) and structural properties (torque, angular defelection, and absorbed energy) of femoral diaphyseal bone tested in torsion to fracture, as well as the effect on these properties of APD (3‐amino‐1‐hydroxypropylidene‐1,1‐bisphosphonate), a drug known to block osteoclast activity. Two dose levels were investigated. Experimental inflammatory arthritis was induced by intra‐articular injection of carrageenan into the right tibiofemoral joint, given over 7 weeks, in three groups of animals. Simulataneously, daily subcutaneous injections of APD were given to three groups of rabbits. Five groups (12 animals each) were established: normal, arthritis, normal/high dose APD, arthritis/high dose APD, and arthritis/low dose APD. The diaphyses of each excised right femur were loaded to fracture in torsion at an angular deflection rate of 8°/sec. In the arthritis group, the fracture toughness was 39% lower than in the normal group, and the structural properties all were reduced significantly. By contrast, the shear modulus was unaffected by arthritis. In this study, the higher dose level (0.3 mg/kg of body weight) of APD prevented loss of fracture toughness and maintained the structural properties in experimental inflammatory arthritis; the low dose was not effective.
Induction of bone by a demineralized bone matrix gel: A study in a rat femoral defect model
Authors: Feighan John E. , Davy Dwight , Prewett Annamarie B. , Stevenson Sharon 
Published: February 2005

AbstractDemineralized bone matrix contains osteoinductive factors and stimulates filling of gaps and defects with bone; however, it is difficult to handle by itself and various preparations have been tested. Demineralized bone matrix with a gel consistency now is available for clinical use. We studied, in a femoral segment defect in the rat, the effects of rat demineralized bone matrix gel with and without a ceramic substratum. This preparation is analogous to the human demineralized bone matrix in the same carrier, used clinically for humans. One hundred adult male Fischer rats were divided into 10 experimental groups. Independent variables included the presence or absence of hydroxyapatite ceramic cylinders, the presence of demineralized bone matrix in carrier or carrier alone (glycerol), and the duration of observation (1, 2 and 4 months). Defects filled with the gel alone had significantly higher radiographic scores for host‐graft union at 4 months compared with ceramic with the gel, ceramic alone, or carrier alone. Demineralized bone matrix gel significantly increased the total histologic score for host‐graft union, whether ceramic was present or not, and a three‐way interaction occurred among ceramic, the gel, and time. Demineralized bone matrix gel was an effective inducer of bone formation in this model. An additional substratum was not required; in fact, significantly more bone was formed in the absence of the ceramic cylinder. Neither the gel nor the ceramic were impediments to revascularization of the defect. Host‐graft union was enhanced by demineralized bone matrix gel but not by the ceramic cylinder.
Tumor osteolysis in osteopetrotic mice
Authors: Clohisy Denis R. , Ogilvie Christian M. , Ramnaraine Margaret L. R. 
Published: February 2005

AbstractDetails of the cellular and biochemical mechanisms involved in focal destruction of bone at sites of tumor osteolysis are unknown. It has been shown that tumors from sarcoma (2472) cell lines induce focal osteolysis in mice by stimulating formation and activation of osteoclasts. In this report, the influence of 2472 tumors on the skeletons of osteoclast‐deficient animals (op/op) was studied. After op/op femora had been inoculated with 2472 cells, tumors developed and focal osteolysis occurred. There were more osteoclasts per histologic section in sham‐injected femora (19 ± 5) than in tumor‐bearing femora (412 ± 129) (p < 0.05). The size of the osteoclasts also increased from 304 ± 81 μm2 in sham‐injected limbs to 407 ± 62 μm2 in tumor‐bearing limbs (p < 0.001). Conditioned media from 2472 op/op tumor explants contained macrophage colony‐stimulating factor. A deficiency of osteoclasts in op/op mice is the result of the absence of this factor; therefore, these data introduce the possibility that macrophage colony‐stimulating factor derived from 2472 tumor may be responsible for directing osteoclast‐mediated osteolysis at sites of the tumor.
Subfracture insult to the human cadaver patellofemoral joint produces occult injury
Authors: Atkinson Patrick J. , Haut Roger C. 
Published: February 2005

AbstractThe current criterion used by the automotive industry for injury to the lower extremity is based on visible bone fracture. Studies suggest, however, that chronic joint degeneration may occur after subfracture impact loads on the knee. We hypothesized that subfracture loading of the patellofemoral joint could result in previously undocumented microtrauma in areas of high contact pressure. In the current study, seven patellofemoral joints from human cadavers were subjected to impact with successively greater energy until visible fracture was noted. Transverse and comminuted fractures of the patella were noted at 6.7 kN of load. Approximately 45% of the impact energy then was delivered to the contralateral joint. Subfracture loads of 5.2 kN resulted in no gross bone fracture in five of seven specimens. Histological examination of the patellae revealed occult trauma in four of the seven specimens in the subfracture group; trauma consisted of a horizontal split fracture in the subchondral bone, at the tidemark, or at the interface of calcified cartilage and subchondral bone. The trauma appeared predominantly on the lateral facet, adjacent to or directly beneath preexisting fibrillation of the articular surface. Surface fibrillation was noted in histological sections of control patellae (not subjected to impact loading), but occult damages were not observed. Although the mechanism of this occult trauma is unknown, similar damage has been shown to occur from direct shear loading. As these microcracks can potentiate a disease process in the joint, this study may suggest that the current criterion for injury, based on bone fracture alone, is not sufficiently conservative.
Localized, tumor‐associated osteolysis involves the recruitment and activation of osteoclasts
Authors: Clohisy Denis R. , Ogilvie Christian M. , Carpenter Randall J. , Ramnaraine Margaret L. R. 
Published: February 2005

AbstractThe cellular and biochemical mechanisms that direct destruction of bone at the site of tumor osteolysis are unknown. In order to understand this process better, a murine model designed for the study of tumor osteolysis was developed and the influence of osteolytic and nonosteolytic tumors on bone was investigated. Tumors developed following femoral intramedullary injection of sarcoma (2472) and melanoma (G3.26) cell lines: however, only tumors from the 2472 cell line caused osteolysis. It was determined that 2472 tumor‐induced osteolysis commenced 6 days after the femora had been inoculated with 2472 cells. There were more osteoclasts per millimeter of bone surface in 2472 tumor‐bearing limbs (16.7 ± 5.0) than in sham‐injected limbs (3.8 ± 0.9) (p < 0.015). In addition, an increase in the osteoclast size (area) was detected in 2472 tumor‐bearing limbs: 412 ± 65 μm2 compared with 187 ± 17 μm2 (p < 0.01). In vitro bone resorption experiments indicated that 2472 tumor cells had a limited ability to destroy bone in comparison with macrophages and osteoclasts. Taken in total, these findings define a model that is useful for the study of tumor osteolysis, and the data from analyses of the model demonstrate that the cellular mechanisms responsible for 2472 tumor‐induced osteolysis include both an increase in the number of osteoclasts and activation of mature osteoclasts.
Role of tumor necrosis factor alpha in particulate‐induced bone resorption
Authors: Algan Sheila M. , Purdon Marie , Horowitz Stephen M. 
Published: February 2005

AbstractThe purpose of this study was to determine the role of tumor necrosis factor alpha in bone resorption secondary to mediator release from macrophages exposed to cement particles. The J774 mouse macrophage cell line was exposed to polymethylmethacrylate particles for 24 hours and the resulting conditioned medium was analyzed for prostaglandin E2, tumor necrosis factor alpha, interleukin‐1 alpha and beta, and the ability to stimulate release of prostaglandin E2 and 45Ca from radiolabeled mouse calvaria. Macrophage exposure to polymethylmethacrylate particles led to a 9‐fold increase in release of tumor necrosis factor alpha (p < 0.01), but did not lead to a significant increase in release of prostaglandin E2, interleukin‐1 alpha, or interleukin‐1 beta when compared to unexposed cells. Exposure of the macrophages to polymethylmethacrylate particles over a time course from 30 minutes to 96 hours led to an increase in the release of tumor necrosis factor alpha that was initially detected at 30 minutes and was maximum at 48 hours. Incubation of the macrophage‐polymethylmethacrylate conditioned medium with rat calvaria significantly increased the release of 45Ca and prostaglandin E2 from the bone. To study the role of release of tumor necrosis factor alpha in bone resorption, the macrophage‐polymethylmethacrylate conditioned medium was then preincubated with anti‐tumor necrosis factor alpha antibody prior to exposure of the conditioned medium to the calvaria. This preincubation was successful in significantly inhibiting 45Ca release by calvaria (p < 0.01) to levels that were not significantly different from the levels of release by unexposed calvaria. Tumor necrosis factor alpha appears to play a critical role in initiating particulate‐induced bone resorption. Exposure of macrophages to polymethylmethacrylate particles leads to a significant release of tumor necrosis factor alpha in a time‐dependent fashion. This macrophage‐polymethylmethacrylate conditioned medium stimulated release of prostaglandin E2 and bone resorption in bone organ culture. The addition of anti‐tumor necrosis factor alpha antibody to this in vitro system inhibited the bone resorption stimulated by the macrophage‐polymethylmethacrylate conditioned medium and partially suppressed the production of prostaglandin E2. The sequence of events in this model for particulate‐induced bone resorption appears to be initiated by the production of tumor necrosis factor alpha by the macrophage, followed by production of prostaglandin E2 by cells in bone, and then by bone resorption.
Equal effectiveness of electrical and volitional strength training for quadriceps femoris muscles after anterior cruciate ligament surgery
Authors: Lieber R. L. , Silva P. D. , Daniel D. M. 
Published: February 2005

AbstractNeuromuscular electrical stimulation and voluntary muscle contraction are two exercise modes widely used in rehabilitation to strengthen skeletal muscle. Since there is debate as to which mode is most effective, we compared electrical stimulation with voluntary contraction performed at matched intensities following reconstructive surgery of the anterior cruciate ligament. Forty men and women, aged 15–44, were randomly assigned to either an electrical stimulation or a voluntary contraction group. None of the subjects had a previous history of neuromuscular injury. The subjects received treatment for 30 minutes a day, 5 days a week, for 4 weeks. Knee extension torque was monitored during treatment to try to match the absolute muscular tensions (quantified as “activity”) achieved during therapy. To match the activity of the subjects in the electrical stimulation group, who were treated at the highest stimulation intensity they could tolerate, the subjects in the voluntary contraction group were paced at progressively increasing intensities corresponding to 15, 25, 35, and 45% of the injured limb's maximum voluntary torque during weeks 1, 2, 3, and 4, respectively. We found no significant difference between the groups in terms of maximum voluntary knee extension torque throughout the study period. In addition, 1 year after surgery, there was still no significant difference between groups with regard to knee extension torque (p > 0.4). These data suggest that neuromuscular electrical stimulation and voluntary muscle contraction treatments, when performed at the same intensity, are equally effective in strengthening skeletal muscle that has been weakened by surgical repair of the anterior cruciate ligament.
Hamstrings and psoas lengths during normal and crouch gait: Implications for muscle‐tendon surgery
Authors: Delp Scott L. , Arnold Allison S. , Speers Rosemary A. , Moore Carolyn A. 
Published: February 2005

AbstractCrouch gait, one of the most common movement abnormalities among children with cerebral palsy, is characterized by persistent flexion of the knee during the stance phase. Short hamstrings are thought to be the cause of crouch gait; thus, crouch gait is often treated by surgical lengthening of the hamstrings. In this study, a graphics‐based model of the lower extremity was used in conjunction with three‐dimensional kinematic data obtained from gait analysis to estimate the lengths of the hamstrings and psoas muscles during normal and crouch gaits. Only three of 14 subjects with crouch gait (four of 20 limbs with knee flexion of 20° or more through stance) had hamstrings that were shorter than normal by more than 1 SD during walking. Most (80%) of the subjects with crouch gait had hamstrings of normal length or longer, despite persistent knee flexion during stance. This occurred because the excessive knee flexion was typically accompanied by excessive hip flexion throughout the gait cycle. All of the subjects with crouch gait had a psoas that was shorter than normal by more than 1 SD during walking. These results emphasize the need to consider the geometry and kinematics of multiple joints before performing surgical procedures aimed at correcting crouch gait.
Proliferative and matrix synthesis response of canine anterior cruciate ligament fibroblasts submitted to combined growth factors
Authors: Desrosiers Eric A. , Yahia L'Hocine , Rivard Charles‐Hilaire 
Published: February 2005

AbstractWe investigated the effects of growth factors on the proliferation and matrix synthesis of anterior cruciate ligament fibroblasts. Fibroblasts from the anterior cruciate ligaments of dogs were transferred at the second passage in a defined medium. Epidermal growth factor, platelet‐derived growth factor‐AB, transforming growth factor‐β1, insulin‐like growth factor‐1, and insulin, combined two by two following a 5 × 5 logarithmic concentration matrix, were added. Tridimensional curves showing cell proliferation at 24 hours against the concentration of two effectors were obtained for each combination. Collagen and proteoglycan productions were quantified using [14 C]glycine and Na2[35S]O4. Ratios of type I:III collagen and hydrodynamic size distributions of proteoglycans were assayed, respectively, by sodium dodecyl sulfate‐polyacrylamidel gel electrophoresis and gel filtration chromatography. Epidermal growth factor had an effect nearly equivalent to that of platelet‐derived growth factor‐AB on cell proliferation. Both had a greater effect than insulin‐like growth factor‐1, which in turn had a greater effect than both the effect of insulin or the nearly equivalent effect of transforming growth factor‐β1. Neither platelet‐derived growth factor‐AB nor insulin has a significant effect by itself on collagen production. Epidermal growth factor slightly decreases collagen production as well as the type I:III collagen ratio: both transforming growth factor‐β1 and insulin‐like growth factor‐1 increase the same parameters. Epidermal growth factor inhibits the stimulation induced by transforming growth factor‐β1. Similarly, insulin decreases the response to insulin‐like growth factor‐1. Proteoglycan production was significantly increased by all growth factors in this study, with transforming growth factor‐β1 having the strongest effect, Small hydrodynamic size of proteoglycan was correlated to a high level of proteoglycan biosynthesis. The results may be readily applied to tissue engineering or provide a basis for in vivo investigations.
Medial collateral ligament healing one year after a concurrent medial collateral ligament and anterior cruciate ligament injury: An interdisciplinary study in rabbits
Authors: Yamaji Tomoo , Levine Rebecca E. , Woo Savio L‐Y. , Niyibizi Christopher , Kavalkovich Karl W. , Weaver‐Green Colleen M. 
Published: February 2005

AbstractThe optimal treatment for concurrent injuries to the medial collateral and anterior cruciate ligaments has not been determined, despite numerous clinical and laboratory studies. The objective of this study was to examine the effect of surgical repair of the medial collateral ligament on its biomechanical and biochemical properties 52 weeks after such injuries. In the left knee of 12 skeletally mature New Zealand White rabbits, the medial collateral ligament was torn and the anterior cruciate ligament was transected and then reconstructed. This is an experimental model previously developed in our laboratory. In six rabbits, the torn ends of the medial collateral ligament were repaired, and in the remaining six rabbits, the ligament was not repaired. Fifty‐two weeks after injury, we examined varus‐valgus and anterior‐posterior knee stability; structural properties of the femur‐medial collateral ligament‐tibia complex; and mechanical properties, collagen content, and mature collagen crosslinking of the medial collateral ligament. We could not detect significant differences between repair and nonrepair groups for any biomechanical or biochemical property. Our data support clinical findings that when the medial collateral and anterior cruciate ligaments are injured concurrently and the anterior cruciate ligament is reconstructed, conservative treatment of the ruptured medial collateral ligament can result in successful healing.
Lower limb alignment and foot angle are related to stance phase knee adduction in normal subjects: A critical analysis of the reliability of gait analysis data
Authors: Andrews Michelle , Noyes Frank R. , Hewett Timothy E. , Andriacchi Thomas P. 
Published: February 2005

AbstractAnatomic and mechanical factors that affect loading in the knee joint can contribute to pathologic changes seen at the knee in degenerative joint disease and should be considered in treatment planning. The objectives of this study were to quantify the relationships between the alignment of the bones of the lower extremity, foot progression angle, and knee adduction moment, and to determine the reliability of our gait measurements. Gait analysis and complete radiographic evaluation of the lower extremity were performed on 11 healthy subjects. The gait measurements were recorded with an optoelectronic digitizer and a multicomponent force plate. The subjects who had radiographic measurements indicative of varus alignment of the lower extremity had statistically higher peaks in knee adduction moment in early stance. Conversely, those with valgus alignment of the lower extremity had statistically lower peaks in knee adduction moment in early stance. The subjects who had a large toe‐out angle and low ankle inversion moment peaks in late stance had significantly lower peaks in knee adduction moment in late stance. These significant (low to moderate) correlations suggest that the limbs with more valgus alignment and those with a toe‐out gait exhibited a reduced peak adduction moment at the knee. To verify the reproducibility of the data, gait analysis testing was performed on each lower limb on 2 separate days for each subject. Analysis of variance showed that there was no significant difference between test limbs or test days for each subject. Our results suggest that the alignment of the lower limb and the foot progression angle, which can be readily measured in a clinical setting, can serve as predictors of knee joint loading in healthy individuals. These findings may have important implications for both surgical and nonsurgical treatment of abnormalities of the knee joint.
Intraosseous infusion of prostaglandin E2 prevents disuse‐induced bone loss in the tibia
Authors: Welch R. D. , Ashman R. B. , Baker K. J. , Browne R. H. 
Published: February 2005

AbstractWe investigated whether intraosseous injection of prostaglandin E2 would preserve tibial bone mass in the skeletally unloaded limb of a large animal model. Skeletal unloading of one rear limb was produced by unilateral Achilles tenectomy in the goat. Prostaglandin E2 was injected at 0.5 or 1.0 mg (1 ml of volume) twice daily, beginning on day 7 and continuing for 10 days, through an implant that had been surgically placed in the proximal tibial metaphysis. Thirty‐five days after surgery, the tibiae were harvested for measurement of static and dynamic bone parameters and mechanical characteristics using transmission ultrasound. Prostaglandin E2 produced a dose‐dependent increase in the formation of woven new bone at all bone envelopes. The 1.0 mg dosage prevented and partially reversed the effects of skeletal unloading and added new bone (p < 0.05) compared with the unloaded tibiae. Because prostaglandin E2 increased both bone formation and resorption and the new bone produced was primarily woven bone, the material properties of the tibiae infused with prostaglandin E2 did not increase significantly during the study compared with the unloaded and weight‐bearing tibiae.
Functional degradation of the rabbit sciatic nerve during noncompressive segmental ischemia
Authors: Kanaya Fuminori , Breidenbach Warren C. , Firrell John C. 
Published: February 2005

AbstractThe purpose of this study was to evaluate functional degradation in a nerve with a local ischemic segment created without a direct compression effect. Ischemia of one segment of a rabbit sciatic nerve was induced by stripping the nerve's extrinsic blood supply along 15 cm. Blood flow of both in situ and ischemic nerves was quantitatively measured with radioactive microspheres in six serial segments in seven animals. The flow in one middle segment of the stripped nerve was significantly reduced to 0.1 ml/min per 100 g (p = 0.006). In another eight animals, both in situ and stripped nerves were metabolically challenged with repetitive stimuli (200 Hz). Conduction velocity and peak amplitude were measured before stimuli, after 30 and 60 minutes of stimuli, and after a 30‐minute recovery period. Conduction velocity was reduced in both nonischemic and stripped nerves during prolonged repetitive stimulation. Peak amplitude was reduced slightly in the nonischemic group and markedly in the stripped group. Normal or higher values were seen again in both groups during the recovery period. It was demonstrated, therefore, that conduction properties of the nerve, especially amplitude, can be affected by localized ischemia in one segment.