bluuebunny/crossref_metadata_2025_split huggingface dataset:
Titanium particles inhibit osteoblast adhesion to fibronectin‐coated substrates
Authors: Kwon Soon Yong , Takei Hiroshi , Pioletti Dominique P. , Lin Tong , Ma Qing Jun , Akeson Wayne H. , Wood Douglas J. , Paul Sung K‐L. 
Published: February 2005

AbstractTo illuminate the effect of titanium particles on osteoblast function, we compared the adhesion force of neonatal rat calvarial osteoblasts on fibronection‐coated glass after incubation with titanium particles (80% had diameters of less than 5 μm). The cells were incubated with the particles for 1.5–72 hours. Using a micropipette single‐cell manipulation system, we showed that the adhesion force of the osteoblasts to fibronectin‐coated glass (1.0 μg/ml) was significantly affected by the presence of particulate debris. The adhesion force of the cells incubated with titanium particles for less than 4 hours was not significantly affected by exposure to the particles; after 4 hours, however, it was significantly reduced relative to that of controls. Aspiration of particle‐challenged osteoblasts into the micropipette demonstrated that the particles were not stripped from the cell surface and therefore confirmed that the osteoblasts had ingested them. During aspiration, the particles traveled through the cytoplasm rather than on the cell surface. When the osteoblasts were exposed to the particles and cytochalasin D, they exhibited much lower adhesion forces than did the controls or the cells exposed to titanium particles only; this indicates and important role of actin filaments in the osteoblastic response to particles. Staining for F‐actin also indicated an influence of internalized titanium particulate on cytoskeletal arrangement and cell spreading. Furthermore, with standard Northern blotting techniques, levels of mRNA for collagen type I and fibronectin were significantly reduced as early as 4 hours after exposure to particles compared with levels in controls, and this effect continued to 72 hours. These data indicate that direct exposure of osteoblasts to titanium particles, which we propose to be ingested by the osteoblasts, can significantly decrease osteoblast adhesion force; this may lead to decreased cellular activity and gene expression of fibronectin and collagen type I in the presence of titanium wear debris.
Expression of mRNA for vascular endothelial growth factor at the repair site of healing canine flexor tendon
Authors: Bidder Miri , Towler Dwight A. , Gelberman Richard H. , Boyer Martin I. 
Published: February 2005

AbstractNeovascularization is an important and prominent feature of tendon healing that contributes to wound repair and potentially to adhesion formation. To define the location of cell populations that recruit and organize the angiogenic response during early healing of flexor tendon, we examined the gene expression pattern of the prototypic angiogenic factor, vascular endothelial growth factor, at and around the tenorrhaphy site in a canine mode! of flexor tendon repair. In situ hybridization with radiolabeled antisense riboprobes was used to identify tendon cell populations that contribute to the neovascularization process by expressing vascular endothelial growth factor and to relate this cell population to the previously described cell populations that participate in matrix synthesis (express type α1(I) collagen) and mitotic renewal (express histone H4). The majority of cells (∼67%) within the repair site itself express vascular endothelial growth factor mRNA: however, minimal levels accumulate within cells of the epitenon (∼10% of cells; p <0.0002). By contrast, expression of type α1(I) collagen and histone H4 does not differ significantly between the epitenon and the repair site (uniformly ∼30% of cells). Thus, a gradient of cell populations expressing vascular endothelial growth factor exists in the repairing tendon. These data suggest a potential contribution of cells with the repair site to the organization of angiogenesis during the early postoperative phase of tendon healing.
Met oncogene aberrant expression in canine osteosarcoma
Authors: Ferracini R. , Angelini P. , Cagliero E. , Linari A. , Martano M. , Wunder J. , Buracco P. 
Published: February 2005

AbstractThe objective of this study was to investigate the role of the MET oncogene in canine osteosarcoma. Seven large‐breed dogs affected by spontaneous skeletal osteosarcoma underwenten bloctumor excision. Total RNA was extracted from frozen tumor samples and assessed for expression of the MET oncogene by Northern blot analysis. Five of seven biopsy samples expressed high levels of the MET oncogene: its expression in the primary tumors was comparable with that previously identified in primary osteosarcomas in humans. A lung metastasis from one of the dogs expressed MET at a higher level than did its primary tumor. Spontaneously arising osteosarcoma in dogs clinically and pathologically mimics the corresponding disease in humans. We previously demonstrated that the MET oncogene was aberrantly expressed in a high percentage of human osteosarcomas. The results of the current study also provide a molecular parallel between the tumors in dogs and humans. Thisin vivomodel may be helpful in evaluating new strategies for therapy against osteosarcoma.
Ability of osteoclast formation from peripheral monocytes using anti‐fusion regulatory protein‐1/cd98/4f2 monoclonal antibodies in patients with osteoporosis
Authors: Tajima Masatoshi , Higuchi Yasumitsu , Miyamoto Noriki , Higuchi Shigeomi , Ito Morihiro , Tsurudome Masato , Sudo Akihiro , Ito Yasuhiko , Uchida Atsumasa 
Published: February 2005

AbstractWe investigated the difference in osteoclast formation between patients with osteoporosis and two healthy control groups by inducing it from peripheral blood monocytes with use of anti‐fusion regulatory protein‐1 monoclonal antibody. The group of patients with osteoporosis consisted of 35 women and excluded secondary osteoporosis, and the control groups consisted of 12 young healthy volunteers (control I) or 10 individuals age‐matched to the patients with osteoporosis (control II). Osteoclast formation declined with age between the two control groups, but this decline was not significant. Fusion rate and the mean number of nuclei in osteoclasts were significantly less in the patients with osteoporosis than in the young or agematched controls. It was clearly demonstrated that the ability of monocytes to fuse declines significantly in patients with osteoporosis.
Tibial plateau fracture as a measure of early estrogen‐dependent bone fragility in rats
Authors: Lotz J. C. , Kroeber M. W. , Heilmann M. , Pericherla K. , Kimmel D. , Kinney J. H. , Lane N. E. 
Published: February 2005

AbstractThe goals of this study were to develop a protocol to induce a compressive fracture at the tibial plateau of the rat knee in vitro and to determine if the biomechanical parameters provided a sensitive assessment of the early skeletal changes induced by estrogen deficiency. Sixty‐one rats underwent an ovariectomy (n = 36) or sham operation (n = 25) and were maintained for 50 days after the procedure. Just before death, the proximal tibia of each animal was scanned with high‐resolution x‐ray tomography. From the three‐dimensional images, the mean trabecular bone volume, thickness, and separation and the number of trabeculae were calculated. The knees were then harvested and mounted into a servohydraulic materials testing system so that the distal femoral condyle could be forced into the proximal tibial plateau until fracture. The fracture load of the ovariectomized rats was 24% less than that of the rats that had the sham operation. Similarly, the structural stiffness of the ovariectomized knees was decreased by 22%. Both of these differences were statistically significant (p < 0.01) and were explained by differences in trabecular bone volume (r = 0.56, p < 0.0001 and r = 0.42, p < 0.005, respectively). The other measures of trabecular bone structure were correlated with the volume and did not improve the prediction by the biomechanical parameters. These data demonstrate that biomechanical testing of the tibial plateau in rats can quantify the structural consequences of estrogen deficiency at an early time point before they become apparent at other bone sites, such as the lumbar spine.
Chondrocyte‐specific Enhancer Regions in the COMP Gene
Authors: Issack Paul S. , Fang Carrie , Leslie Michael P. , Di Cesare Paul E. 
Published: February 2005

AbstractThe molecular events governing the differentiation of mesenchymal cells into chondrocytes and the expression of cartilage marker genes are poorly understood. Cartilage oligomeric matrix protein is a non collagenous extracellular matrix protein with a relatively cartilage‐specific spatial and temporal expression pattern. To understand the mechanisms controlling chondrocyte‐specific expression of cartilage oligomeric matrix protein, we cloned 1.9 kb of the 5′ flanking promoter sequence of the murine cartilage oligomeric matrix protein gene and identified two spatially distant cartilage‐specific enhancer regions by deletion analysis. One element is situated proximally (proximal positive element: −125 to −75) and a second region is located distally (distal positive region: −1925 to −592) relative to the transcription start site. Interestingly, nucleotides within the proximal positive element are conserved between the mouse and human promoters and resemble consensus sites for the binding of members of the high mobility group class of transcription factors. Defining cartilage‐specific regulatory elements in the cartilage oligomeric matrix protein promoter may provide useful molecular probes for identifying transcription factors that control acquisition of the chondrocytic phenotype.
Cell attachment, collagen binding, and receptor analysis on bovine articular chondrocytes
Authors: Reid David L. , Aydelotte Margaret B. , Mollenhauer Jurgen 
Published: February 2005

AbstractThe purpose of this study was to investigate collagen receptors on primary bovine articular chondrocytes from full‐thickness and different layers of bovine articular cartilage. Cytometric studies with antibodies showed that approximately 56% of the chondrocytes from the superficial layer and 29% of the chondrocytes from the deep layer bound anti‐annexin V. A similar tendency was found for α and β1 integrin antibodies. Flow cytometric analysis initially detected annexin V on chondrocytes following isolation; the level of detection subsequently decreased by 24 hours, whereas that of α5 and β1 integrins increased. Treatment of chondrocytes with collagenase at 24 hours restored the initially high epitope recognition of annexin V, indicating masking of annexin V by newly formed collagen matrix. There was little effect on detection levels for β1 integrin. Contrary to the specific matrix receptor expression, chondrocytes from superficial and deep layers differed little in attachment to immobilized types I and II collagens. However, the attachment was more effectively inhibited with anti‐annexin V than with integrin antibodies. Competition studies with preparations of soluble collagens revealed a preferential binding of bovine type‐II collagen compared with bovine type‐I collagen. Anti‐annexin V antibodies inhibited binding of type‐II collagen more effectively than anti‐α5 or anti‐β1 integrin antibodies. Evidently, under the in vitro conditions of this study, annexin V is the quantitatively predominant type‐II collagen receptor on bovine articular chondrocytes. This opens a discussion of the possibly dualistic metabolic/mechanical annexin V‐integrin receptor elements.
Biomechanical investigations on chondromalacia of the knee after meniscal flap lesion and partial meniscal resection: An experimental model
Authors: Grifka Joachim K. , Kalteis Thomas , Broll‐Zeitvogel Eliane , Philippou Stathis , Plitz Wolfgang 
Published: February 2005

AbstractMeniscal tears and resections may cause chondral lesions of the knee. To eliminate muscular control during investigation of this problem, we designed a biomechanical setup based on a knee‐joint simulator, ensuring physiological, free‐motion mobility of the joint. Fresh human knee specimens with intact cartilage were exposed to loads to 2.000 N at a frequency of 0.85 Hz during 48 hours of gait. After a preliminary test series. 18 specimens were divided into three groups: group I was tested with unchanged meniscal status, group II with arthroscopically induced mobile flap tears at the posterior horns of the menisci, and group III after partial resection of the posterior horns. Motion patterns between the groups changed after as little as a few hours due to increased translation in group III. Macroscopic and histological examination and scanning electron microscopy revealed severe chondromalacic changes after meniscal resection. We conclude that meniscal resection—however partial—may have considerable joint‐damaging potential if muscle control is lacking whereas mobile flap tears maintain stability. Our findings might explain the differences in clinical reports on cartilage status after partial meniscal resection. This study underlines the importance of muscle training when active stabilisation of the knee is reduced after partial meniscal resection.
Effect of freeze‐drying and gamma irradiation on the mechanical properties of human cancellous bone
Authors: Cornu O. , Banse X. , Docquier P. L. , Luyckx S. , Delloye Ch. 
Published: February 2005

AbstractFreeze‐drying and gamma irradiation are commonly used for preservation and sterilization in bone banking. The cumulative effects of preparation and sterilization of cancellous graft material have not been adequately studied, despite the clinical importance of graft material in orthopaedic surgery. Taking benefit from the symmetry of the left and right femoral heads, the influence of lipid extraction followed by freeze‐drying of a femoral head and a final 25‐kGy gamma irradiation was determined, with the nonirradiated, nonprocessed counterpart as the control. Five hundred and fifty‐six compression tests were performed (137 pairs for the first treatment and 141 pairs for the second). Mechanical tests were performed after 30 minutes of rehydration in saline solution. Freeze‐dried femoral heads that had undergone lipid extraction experienced reductions of 18.9 and 20.2% in ultimate strength and stiffness, respectively. Unexpectedly, the work to failure did not decrease after this treatment. The addition of gamma irradiation resulted in a mean drop of 42.5% in ultimate strength. Stiffness of the processed bone was not modified by the final irradiation, with an insignificant drop of 24%, whereas work to failure was reduced by a mean of 71.8%. Freeze‐dried bone was a bit less strong and stiff than its frozen control. Its work to failure was not reduced, due to more deformation in the nonlinear domain, and it was not brittle after 30 minutes of rehydration. Final irradiation of the freeze‐dried bone weakened its mechanical resistance, namely by the loss of its capacity to absorb the energy (in a plastic way) and a subsequent greater brittleness.
Multidrug resistance‐1 gene expression does not increase during tumor progression in the MGH‐OGS murine osteosarcoma tumor model
Authors: Trammell Rita A. , Johnson Clifford B. , Barker John R. , Bell Robert S. , Allan D. Gordon 
Published: February 2005

AbstractIn addition to its possible role in drug resistance, expression of the multidrug resistance‐1 gene may also be associated with a more malignant phenotype and tumor progression. This study evaluated its expression during tumor progression in the MGH‐OGS transplantable murine osteosarcoma tumor model. Three variables of tumor progression were analyzed: tumor size, local recurrence, and metastasis. With a highly sensitive reverse transcription‐polymerase chain reaction method, mRNA levels of multidrug resistance‐1 were compared in primary tumors of different sizes. In addition, the levels were compared in primary, locally recurrent, and metastatic tumors isolated from individual mice. No significant difference was found in the levels of expression with increasing primary tumor size. In addition, the levels in primary, locally recurrent, and metastatic tumors were not significantly different. Our results indicate that—at least in the MGH‐OGS tumor model, which is analogous to the majority of spontaneously occurring human osteosarcomas in that it has low levels of multidrug resistance‐1/P‐glycoprotein and is sensitive to doxorubicin—there is no evidence of upregulation of multidrug resistance‐1 expression during tumor progression.
Mechanical behavior of two hamstring graft constructs for reconstruction of the anterior cruciate ligament
Authors: Höher Jürgen , Scheffler Sven U. , Withrow John D. , Livesay Glen A. , Debski Richard E. , Fu Freddie H. , Woo Savio L‐Y. 
Published: February 2005

AbstractWe compared the mechanical behavior of two common hamstring graft constructs that are frequently used for reconstruction of the anterior cruciate ligament—Graft A: quadrupled semitendinosus tendon fixed with titanium button/polyester tape and suture/screw post, and Graft B: a double semitendinosus and double gracilis tendon fixed with a cross pin and two screws over washers. The experimental protocol used to evaluate each graft construct included stress relaxation (with and without preconditioning), cyclic loading, and a tensile load‐to‐failure test. The amount of stress relaxation without preconditioning was 60.6% for Graft A and 53.8% for Graft B. With preconditioning, it significantly decreased (p < 0.05) to 48.7 and 42.3%. respectively. Elongation of the graft construct in response to 100 cycles of loading (20–150 N) was 1.8 and 0.6% of the original length for Grafts A and B. respectively. However, after a series of five cyclic loading tests, the residual permanent elongation for each construct was 3.8 ± 1.2 and 0.3 ± 0.2 mm, a significant difference (p < 0.05) between the two graft constructs. Further analysis found more than 90% of the permanent elongation in the proximal and distal regions of Graft A, which consisted of polyester tape tied to a titanium button (proximal) and sutures tied around a screw post (distal). The tensile load‐to‐failure tests also revealed significant differences (p < 0.05) between the two graft constructs. Linear stiffness was 32 ± 1 and 119 ± 19 Nmm and ultimate load was 415 ± 36 and 658 ± 128 N for Grafts A and B, respectively. For Graft A, the polyester tape consistently failed; for Graft B, slippage or tearing from the washers was the mode of failure. We conclude that a quadruple‐hamstring graft fixed over a cross pin proximally and with metal washers distally (Graft B) has less permanent elongation in response to cyclic loading and has structural properties superior to those of a graft construct that includes suture and tape material (Graft A). The large permanent elongation following repetitive loading of a graft construct with tape and suture material during the early postoperative period is of concern.
The pentapeptide NKISK affects collagen fibril interactions in a vertebrate tissue
Authors: Dahners Laurence E. , Lester Gayle E. , Caprise Peter 
Published: February 2005

AbstractThe pentapeptide NKISK has been reported to inhibit the binding of decorin, a proteoglycan on the surface of collagen fibrils, to fibronectin, a tissue adhesion molecule. Because of our interest in fibril‐fibril binding as it relates to changes in length of ligament or tendon (during growth or contracture), we investigated the potential of this peptide to dissociate fibrils. The peptide permitted the release of intact fibrils into suspension for examination under the electron microscope (which has not previously been possible in mature vertebrate tissues).
Insulin‐like growth factor‐I is expressed by avian flexor tendon cells
Authors: Tsuzaki Mari , Brigman Brian E. , Yamamoto Juro , Lawrence W. Thomas , Simmons James G. , Mohapatra Nirupama K. , Lund P. Kay , Van Wyk Judson , Hannafin Jo A. , Bhargava Madhu M. , Banes Albert J. 
Published: February 2005

AbstractCells in normal tendon are in a resting G0 state, performing maintenance functions. However, traumatic injury introduces growth factors such as platelet‐derived growth factor and insulin‐like growth factor from blood as well as activates endogenous growth factors. These factors stimulate migration and proliferation of tendon cells at the wound area. Tendon cells require growth‐promoting factors to transit the cell cycle. To evaluate the contribution of endogenous growth factors in tendon, extracts of the epitenon and internal compartment of avian flexor tendon as well as medium of cultured cells from the epitenon (tendon surface cells) and internal tendon (tendon internal fibroblasts) were collected to assess their ability to stimulate DNA synthesis. Acid‐ethanol extracts of tissues and medium were chromatographed on a P‐30 molecular sieve column and assayed for mitogenic activity by quantitating [3H]thymidine incorporation into tendon cell DNA. The extract from the internal tendon compartment was more stimulatory for DNA synthesis than that from the epitenon, particularly when tested on tendon internal fibroblasts. However, conditioned medium fractions from surface epitenon cells stimulated DNA synthesis to a high degree on both tendon surface cells and tendon internal fibroblasts. Conditioned medium from tendon internal fibroblasts was also stimulatory. An anti‐insulin‐like growth factor‐I antibody ablated most of the mitogenic activity present in both tissues and conditioned medium. The levels of acid‐extractable insulin‐like growth factor‐I in tendon were determined by competitive radioimmunoassay as 1.48 ± 0.05 ng/g tissue for the epitenon and 3.83 ± 0.03 ng/g tissue for the internal compartment. Results of Western immunoblots of conditioned medium revealed insulin‐like growth factor‐I at the 7.5 kDa position. Cultured tendon surface cells and tendon internal fibroblasts as well as cells in intact flexor tendon expressed insulin‐like growth factor‐I mRNA detected by reverse transcriptase‐polymerase chain reaction. In situ hybridization histochemistry positively identified insulin‐like growth factor‐I mRNA in tendons from 52‐day‐old chickens. Platelet‐derived growth factor was not detected at the protein or message levels. Furthermore, tendon surface cells and tendon internal fibroblasts both expressed receptors for insulin‐like growth factor‐I detected by flow cytometry. These data suggest that tendon cells express insulin‐like growth factor‐I mRNA and synthesize insulin‐like growth factor‐I in both the epitenon and the internal compartment of tendon, which is present in an inactive from, most likely bound to insulin‐like growth factor‐binding proteins.