bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gait compensations in patients with osteoarthritis of the hip and their relationship to pain and passive hip motion
Authors: Hurwitz D. E. , Hulet C. H. , Andriacchi T. P. , Rosenberg A. G. , Galante J. O. 
Published: February 2005

AbstractThis study related mechanisms of gait compensations to the level of pain and to limitations in passive motion in patients with osteoarthritis of the hip. Joint motion, moments, and intersegmental forces were calculated for 19 patients with unilateral osteoarthritis of the hip (12 men and seven women) and for a group of normal subjects (12 men and seven women) with a similar age distribution. The patients who had osteoarthritis walked with a decreased dynamic range of motion (17 ± 4°) of the hip and with a hesitation or reversal in the direction of the sagittal plane motion as they extended the hip. The patients with a hesitation or reversal in motion had a greater loss in the range of motion of the hip during gait (p < 0.004) and a greater passive flexion contracture (p < 0.022) than those with a smooth pattern of hip motion. This alteration in the pattern of motion was interpreted as a mechanism to increase effective extension of the hip during stance through increased anterior pelvic tilt and lumbar lordosis. The patients who had osteoarthritis of the hip walked with significantly decreased external extension, adduction, and internal and external rotation moments (p < 0.008). The decreased extension moment was significantly correlated with an increased level of pain (R = 0.78; p < 0.001). This finding suggests that decreasing muscle forces (hip flexors) may be one mechapism used to adapt to pain.
Ligament creep cannot be predicted from stress relaxation at low stress: A biomechanical study of the rabbit medial collateral ligament
Authors: Thornton G. M. , Oliynyk A. , Frank C. B. , Shrive N. G. 
Published: February 2005

AbstractIn normal daily activity, ligaments are probably subjected to repeated loading rather than to repeated deformation. The viscoelastic response to repeated loading is creep; this effect has significance for ligament reconstructions, which potentially “stretch out” over time. However, most experimental studies have examined the viscoelastic response to repeated deformation, stress relaxation. We hypothesized that the creep of a ligament could be predicted from its stress‐relaxation behaviour. Left and right medial collateral ligaments of eight skeletally mature rabbits were subjected to either creep or stress‐relaxation testing under comparable conditions. The time‐dependent increase in strain (creep) and reduction in load (relaxation) from the tests were modelled with use of the quasilinear viscoelastic theory and generalized standard linear solid modelling. Ligaments were found to creep distinctly less than would be predicted from relaxation tests. Although the reason for this behaviour remains unknown, we speculate that it is due to the progressive recruitment of collagen fibres during creep.
Hyperpolarisation of cultured human chondrocytes following cyclical pressure‐induced strain: Evidence of a role for α5β1 integrin as a chondrocyte mechanoreceptor
Authors: Wright M. O. , Nishida K. , Bavington C. , Godolphin J. L. , Dunne E. , Walmsley S. , Jobanputra P. , Nuki G. , Salter D. M. 
Published: February 2005

AbstractMechanical stimuli influence chondrocyte metabolism, inducing changes in intracellular cyclic adenosine monophosphate and proteoglycan production. We have previously demonstrated that primary monolaycr cultures of human chondrocyles have an electropysiological response after intermittent pressure‐induced strain characterised by a membrane hyperpolarisation of approximately 40%. The mechanisms responsible for these changes are not fully understood but potentially involve signalling molecules such as integrins that link extracellular matrix with cytoplasmic components. The results reported in this paper demonstrate that the transduction pathways involved in the hyperpolarisation response of human articular chondrocytes in vitro after cyclical pressure‐induced strain involve α5β1 integrin. We have demonstrated, using pharmacological inhibitors of a variety of intracellular signalling pathways, that the actin cytoskeleton, the phospholipase C calmodulin pathway, and both tyrosine protein kinase and protein kinase C activities are important in the transduction of the electrophysiological response. These results suggest that α5β1 is an important chondrocyte mechanoreceptor and a potential regulator of chondrocyte function.
Improved osteoinduction of cortical bone allografts: A study of the effects of laser perforation and partial demineralization
Authors: Lewandrowski Kai‐Uwe , Tomford William W. , Schomacker Kevin T. , Deutsch Thomas F. , Mankin Henry J. 
Published: February 2005

AbstractMassive cortical bone allografts have been found to incorporate slowly into host bone and thus are subject to complications such as nonunion, fatigue fracture, and infection. To better understand and improve the process of osteoinduction in these types of bone grafts, a new experimental model was developed with use of diaphyseal cortical bone grafts from rat tibiae that were prepared by partial mineralization and drilling of 0.33 mm diameter holes with a pulsed, 2.94 μm wavelength, erbiunr:yttrium‐aluminum‐garnet laser. Six types of grafts were analyzed: untreated (Type I), demineralized 25 μm deep (Type II), demineralized 150 μm deep (Type III), laser perforated (Type V), laser perforated and then demineralized 25 μm deep (Type V), and laser perforated and then demineralized 150 μm deep (Type VI). The graft was orthotopically transplanted in the tibia of an adult Sprague‐Dawley rat and followed for as long as 4 months. Histologic evaluation at 1 and 4 months postoperatively with use of hematoxylin and eosin staining confirmed that there was new bone growth in Types II, III, V, and VI grafts. The amount of growth was estimated by comparing bone mineral density before implantation with values obtained after retrieval of the graft. These measurements were correlated to histomorphometric analysis of graft incorporation. The results show that the processes of partial demineralization (p < 0.000001) and laser perforation with partial demineralization (p < 0.000001) were both significant in enhancing bone growth in this model. New bone growth was significantly increased when the grafts were prepared with extensive demineralization (p < 0.015). This study demonstrates that osteogenesis in cortical bone grafts can be fostered through the process of partial demineralization and laser perforation. To the extent that minimal partial demineralization and laser perforation allow maintenance of Structural integrity while altering the osteoinductive properties in such a way as to promote ingrowth of new bone, this experimental model represents an advance in understanding how osteogenesis in cortical bone grafts may be improved.
Assessment of cell proliferation in regenerating bone during distraction osteogenesis at different distraction rates
Authors: Li G. , Simpson A. H. R. W. , Kenwright J. , Triffitt J. T. 
Published: February 2005

AbstractAn experimental model of lengthening of the lower limb was used to study the morphology and cellular proliferation of regenerating bone tissue after 20% lengthening at four rates of distraction. Groups of rabbits were killed at different times 1‐8 weeks after surgery. The regenerated area was divided into three zones: fibrous, primary mineralization front, and new bone. As the rate of distraction increased, the size of the fibrous zone increased and that of Ihe new bone. one decreased. Necrosis, formation of cysts, and cartilage were found in the regenerated area at the higher distraction rates. Cell proliferation was assessed by in vivo labelling with' bromodeoxyuridine and the positive staining index for anti‐bromodeoxyuridine antibody was calculated in the zones of the regenerated tissue, The index values for the fibrous zones and the new bone zones did not differ significantly in any of Ihe groups, The value increased significantly (p < 0,05) in the primary mineralization front as the rate of distraction increased from 0.3 to 0.7 mm/day, but there was no further significant increase at higher distraction rates. In conclusion, cell proliferation was increased at all of the higher rates (more than 0.3 mm/day) of distraction studied. Higher rates of distraction caused tissue damage. A distraction rate of 0.7 mm/day appeared optimal for cell proliferation and histological characteristics.
Effect of cisplatin chemotherapy on extracortical tissue formation in canine diaphyseal segmental replacement
Authors: Young David R. , Shin Lih‐Yuann , Rock Michael G. , Frassica Frank J. , Virolainen Petri , Chao Edmund Y. S. 
Published: February 2005

AbstractThe reconstruction of large bone and joint defects after the resection of malignant tumors remains a major challenge. Chemotherapy has significantly lowered the risk of metastasic disease, but complications associated with reconstructive techniques continue to result in late morbidity. In the present study, biomechanical torsion testing, gait analysis, and histomorphometric and scanning electron microscopic evaluations of 24 dogs were used to examine the effects of preoperative and postoperative administration of cisplatin on the biologic fixation of a porous‐coated segmental replacement prosthesis. The chemotherapy consisted of four cycles of cisplatin administered at a dosage of 75 mg/m:2 preoperatively or postoperatively. The healing was enhanced by use of an autogenous corticocancellous bone graft. The graft was placed evenly around the prosthesis and the adjacent femoral cortex. Mechanical analyses of torsional stiffness, yield strength, and maximum strength revealed no statistically significant differences between the groups at 12 weeks. Such lack of difference was mainly due to the penetration of highly organized fibrous tissue into the porous surface; this provided strong fixation of the implant to bone even in the absence of bone ingrowth. Although bone ingrowth into the prostheses was not affected, electron microscopic, histomorphometric, and radiologic analyses showed a clear difference in the formation of new bone around the prosthesis. Preoperative chemotherapy did not alter the formation of new bone, but specimens from animals treated postoperatively with cisplatin showed significantly less bone graft resorption and less new bone formation. Hence, the effect of cisplatin administration caused only a temporary delay, not a permanent effect, on extracortical capsule formation. The formation of extracortical bone and soft tissue might prevent debris‐incised osteolysis and, therefore, prevent late complications by forming a tight capsule around the bone‐prosthetic interface.
Dependence of trabecular damage on mechanical strain
Authors: Wachtel Edward F. , Keaveny Tony M. 
Published: February 2005

AbstractTrabecular damage may play a role in hip fracture, bone remodeling, and prosthesis loosening. We hypothesized that when trabecular bone is loaded beyond its elastic range, both the type and the amount of damage depend on the applied strains. Thirty specimens of trabecular bone from the bovine tibia underwent compression tests to one of three levels of strain (0.4,1.0, and 2.5%) (n = 10 per group). The 0.4% level was a mechanically nondestructive control group that accounted for any systematic errors. Optical microscopy at magnifications as high as × 200 was then used to quantify the trabecular damage for each group. The amount of damage in the yield group (1.0% strain) did not differ from that in the control group (p = 0.66), whereas damage in the post‐ultimate strain group (2.5% strain) increased more than 3‐fold (p < 0.0008). Four types of damage were observed: transverse cracks, shear bands, parallel cracks, and complete fractures, of which the first two were dominant. These findings therefore indicate that damage occurs within trabeculae at yield. By comparison with our previous work, it can also be concluded that substantial modulus reductions in trabecular bone (as much as 60%) are caused by damage primarily within trabeculae. The ability to detect such damage clinically may improve in vivo estimates of whole‐bone strength by identifying regions of densito metrically normal but mechanically compromised trabecular bone.
Temporal and spatial expression of transforming growth factor‐β in the healing patellar ligament of the rat
Authors: Natsuume Takashi , Nakamura Norimasa , Shino Konsei , Toritsuka Yukiyoshi , Horibe Shuji , Ochi Takahiro 
Published: February 2005

AbstractWe investigated the temporal and spatial expression of transforming growth factor‐β in the healing patellar ligament of the rat by immunohistochemistry. The mid‐portion of the medial half of the patellar ligament in 14‐week‐old male Wistar rats was cut transversely with a scalpel. On day 1 after ligament injury, diffuse staining for transforming growth factor‐β was observed in the extracellular matrix filling the wound, and the staining in the adjacent ligament tissue was as weak as it was in the normal ligament. On day 3, the intensity of the diffuse extracellular staining decreased, and the staining was observed in correspondence with the cellular distribution in the wound site and in the adjacent uninjured ligament tissue. On day 7, the intense staining was widely distributed over the whole length of the ligament tissue. On day 28, the staining for transforming growth factor‐β was still observed at the wound site and in the adjacent uninjured ligament tissue, where the staining was reduced in intensity but still stronger than it was in the normal ligament. On day 56, the expression of transforming growth factor‐β was still detectable at the wound site: however, in the adjacent uninjured ligament tissue, it had almost subsided to the normal level. The results of the present study suggest that ligament healing may be accompanied by extensive changes in the expression of transforming growth factor‐β over the whole length of ligament tissue.
Fibre type characteristics of the lumbar paraspinal muscles in normal healthy subjects and in patients with low back pain
Authors: Mannion Anne F. , Weber Barbara R. , Dvorak Jiri , Grob Dieter , Müntener Markus 
Published: February 2005

AbstractA knowledge of the alteration in the fibre type profile of paraspinal muscle associated with low back pain is essential for the design of successful rehabilitation programmes. In attempting to compare the muscles of patients with low back pain with those of controls, few previous studies have considered factors such as gender, age, and size of the subjects, each of which can potentially confound interpretation of the results. We obtained samples of lumbar paraspinal muscle during spinal surgery from 21 patients with low back pain and, using the percutaneous biopsy technique, from 21 control volunteers matched for gender, age, and body mass. The samples were subject to routine histochemicsl typcal analysis to determine characteristics of muscle fibre type. Compared with controls, the muscle of the patients had a significantly higher proportion of type‐IIB (fast‐twitch glycolytic) fibres than type‐ I (slow oxidatve) fibres. The mean size of a given fibre type did not differ between the patients and the controls. Consequently, the relative area of the muscle iccupied by type‐IIB fibres was higher and that by type‐I fibres Was lower in the patients. The patients had a greater number of muscle samples with more than 1% type‐IIC fibres, and abnormalities that could be described as pathological were more marked in the patients than in the controls. In conclusion, the paraspinal muscles of patients who have low back pain display a more glycolytic (faster) profile; this can be expected to render them less resistant to fatigue.
Staphylococcal septic arthritis: Antibiotic and nonsteroidal anti‐inflammatory drug treatment in a rabbit model
Authors: Smith R. Lane , Kajiyama G. , Schurman D. J. 
Published: February 2005

AbstractThis study evaluated the effects of combining antibiotic therapy with the application of a nonsteroidal anti‐inflammatory drug on the degradation of articular cartilage for an animal model of Staphylococcal septic arthritis. Rabbits were infected intra‐articularly with Staphylococcus aureus. Antibiotic treatment started 18 hours after infection and continued for 7 days. Treatment with the nonsteroidal anti‐inflammatory drug naproxen sodium started 24 hours before infection and continued for either 3 or 7 weeks. The cartilage matrix of uninfected and infected knees was quantified by analysis of glycosaminoglycan and collagen content. Three weeks after infection, the combined treatment of the nonsteroidal anti‐inflammatory drug and antibiotics reduced the loss of glycosaminoglycan and collagen from the cartage of the infected knee by 15 and 30%, respectively, compared with antibiotic treatment alone. Continuing treatment with naproxen sodium for 7 weeks reduced the loss of collagen by 50% when compared with antibiotic treatment alone. The longer period of treatment with naproxen sodium showed little further effect on the loss of glycosaminoglycan than that observed for the 3‐week treatment. Treatment with this drug and antibiotics reduced swelling of the knee and levels of prostaglandin E2 in the synovial fluid. The data support the hypothesis that decreasing post‐infectious inflammation by adding the drug to a standard antibiotic regimen reduces cartilage damage from Staphylococcal septic arthritis.
Prognostic relevance of C‐myc gene expression in giant‐cell tumor of bone
Authors: Gamberi Gabriella , Benassi M. Serena , Böhling Tom , Ragazzini Paola , Molendini Lara , Sollazo M. Rosa , Merli Mara , Ferrari Cristina , Magagnoli Giovanna , Bertoni Franco , Picci Piero 
Published: February 2005

AbstractGiant‐cell tumor is a primary bone tumor, of uncertain origin, with the potential capacity to metastasize. To study the role of c‐myc and c‐fos oncogene overexpression in the tumorigenesis and metastatic spread of giant‐cell tumors. 32 primary tumors were collected: of these. 19 remained disease‐free and 13 metastasized to the lung. Samples of lung metastasis from these 13 patients were also available for study. The expression of c‐myc and c‐fos mRNA was studied by reverse transcription‐polymerase chain reaction and by in situ hybridization. The expression of protein was studied by Western blot analysis and by immunohistochemistry. C‐myc mRNA was overexpressed in 12 (38%) of the 32 primary tumors. Thirteen primary tumors metastasized to the lung: in nine (69%) of these. c‐myc mRNA was overexpressed. The c‐myc protein was overexpressed in seven (54%) of the 13 tumors that metastasized to the lung. C‐fos was overexpressed in only one lung metastasis. A strong correlation between the overexpression of c‐myc and the occurrence of metastases was found: thus, c‐myc seems a powerful prognosticator in giant‐cell tumor. C‐myc was overexpressed both in giant cells and in mononuclear cells, suggesting that both cell types are involved in the progression of this tumor.
Role of glutathione in cisplatin resistance in osteosarcoma cell lines
Authors: Komiya S. , Gobhardt M. C. , Mangham D. C. , Inoue A. 
Published: February 2005

AbstractThis study was designed to examine whether and how glutathione and catalase increase the resistance of osteosarcoma cells to the toxicity of cisplatin. Eight osteosarcoma cell lines were exposed to varying concentrations of cisplatin. and a [3H]thymidine incorporation study then estimated their drug sensitivity. Cells were pretreated with aminotriazole and buthionine sulfoximine to depress catalase and glutathione activities and then entered into the same protocol to assess their sensitivity to cisplatin. Intracytoplasmic levels of catalase and glutathione were measured before and after the treatments. Cisplatin‐glutathione conjugates were created to examine how glutathione might depress the toxicity of cisplatin. Although the cell lines differed in the magnitude of their response to cisplatin, there was a statistical correlation between intrinsic glutathione content and cisplatin resistance. Pretreatment with aminotriazole reduced catalase activity by 84% but did not change the sensitivity to cisplatin. Depletion of glutathione activity by 70% increased the sensitivity of the cells to the cytotoxicity of cisplatin. In addition, cisplatin was detoxified following conjugation with glutathione. The increased sensitization to cisplatin toxicity caused by the depletion of glutathione and cisplatin detoxification after the in vitro reaction of glutathione to cisplatin indicated that the formation of the glutathione‐cisplatin conjugate was an important mechanism in the cellular resistance to cisplatin. These data also demonstrated that catalase activity did not contribute to resistance to cisplatin and suggested that H2O2‐induced oxidative stress did not significantly contribute to the cytotoxicity of cisplatin in osteosarcoma cells.
Relationships between bone morphology and bone elastic properties can be accurately quantified using high‐resolution computer reconstructions
Authors: Van Rietbergen B. , Odgaard A. , Kabel J. , Huiskes R. 
Published: February 2005

AbstractIt would be advantageous if the mechanical properties of trabecular bone could be directly inferred from stereomorphometric parameters. For that purpose, apparent density and mean intercept length, as measures of bone mass and directionality (fabric), are commonly correlated with the elastic characteristics of bone samples, as determined in compression tests. However, complete and accurate relationships have not yet been established in this way. This may be due not only to the occurrence of artifacts in both the stereomorphometric and the mechanical assessments but also to an inherent inadequacy of mean intercept length in characterizing the full mechanical significance of bone architecture or nonhomogeneities in trabecular tissue properties not accounted for in stereomorphometry. In this study, we introduce a computer modeling approach allowing these biases to be eliminated. With use of high‐resolution three‐dimensional computer reconstructions of trabecular bone specimens for stereomorphometry and for microstructural finite element models to simulate mechanical tests, unbiased comparisons become feasible. The purpose was to investigate if accurate and complete relationships can be established in this way. Four different fabric measures were considered: mean intercept length and three volume‐based ones. Compliance matrices were calculated from fabric tensors, with use of the mathematical relationship proposed by Cowin for 29 vertebral whale‐bone specimens. These were correlated with the compliance constants determined directly from the microstructural finite element, model simulation. The nine orthotropic elastic constants of all 29 specimens were well predicted from their stereomorphometric fabric and volume fraction values, with correlation coefficients ranging from R = 0.9934 to O. 9963. When individual compliance components were considered (1/Ei,. 1/Gij, or ‐vij/Ei), correlation coefficients ranged from R = 0.924 to 0.9X2. All four fabric measures performed equally well. It is concluded that volume fraction and fabric measures correlate highly with the apparent elastic properties of bone samples, provided the anisotropy and nonhomgoencity in the elastic properties of the trabecular tissue itself have negligible effects on the apparent propertie Whether this is true for bone in general remains to be seen, as only a subset was analyzed here. These methods, however, can be valuable in similar assessments of other subsets.