bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationship of donor site to chondrogenic potential of periosteumin vitro
Authors: Gallay Stephen H. , Miura Yasushi , Commisso Cinzia N. , Fitzsimmons James S. , O'Driscoll Shawn W. 
Published: February 2005

AbstractPeriosteum has been shownin vitroandin vivoto have a chondrogenic potential that permits it to be used for cartilage regeneration. A useful donor site should have good chondrogenic potential, availability of a large quantity of periosteum, and relative ease of access, and it should be associated with a low rate of morbidity. We hypothesized that the chondrogenic potential of periosteum varies from one bone to another and among different regions of the periosteum from a single bone. A total of 370 periosteal and 37 fascia lata (control) explants were taken from the skull, the ilium, the scapula, the upper, middle, and lower medial proximal tibia, the posterior proximal tibia, and the distal tibia of 2‐month‐old New Zealand rabbits. The explants were cultured for 6 weeks in agarose/Dulbecco's modified Eagle medium to which 10 ng/ml of transforming growth factor‐β1 was added during the first 2 weeks. Skeletal muscle and fascia lata were used as controls. In addition, the thickness, cell density, and total cell count of the cambium layer were measured in 24 explants from the donor sites on the ilium and the upper, middle, and lower proximal tibia. At 6 weeks, histomorphometry and quantitative collagen typing were performed. The periosteal donor sites could be grouped into three categories according to chondrogenic potential: ilium (best), scapula and tibia, and skull (no chondrogenesis). The scapular periosteum was slightly better than that from the tibia. Within the tibia, the upper and middle zones of the proximal region were similar and were slightly better than the lower proximal tibia or the distal tibia. The cellularity of the cambium layer correlated positively with the amount of cartilage as a percentage of the total area. The results of this study indicate that iliac periosteum exhibited the best overall chondrogenic potentialin vitrobut that periosteum from the traditionally used medial proximal tibia also was excellent. Periosteum from the skull was not chondrogenic. The chondrogenic potential of periosteum varies from bone to bone and within the periosteum from one bone. This variation in chondrogenic potential among donor sites may be due to a difference in the total cell count of the cambium layer.
Culture surfaces coated with various implant materials affect chondrocyte growth and metabolism
Authors: Hambleton J. , Schwartz Z. , Khare A. , Windeler S. W. , Luna M. , Brooks B. P. , Dean D. D. , Boyan B. D. 
Published: February 2005

AbstractThe effect on chondrocyte metabolism of culture surfaces sputter‐coated with various materials used for orthopaedic implants was studied and correlated with the stage of cartilage cell maturation. Confluent, fourth‐passage chondrocyts from the costochondral resting zone and growth zone of rats were cultured for 6 or 9 days on 24‐well plates sputter‐coated with ultrathin films of titanium, titanium dioxide, aluminum oxide, zirconium oxide, and calcium phosphate (1.67:1). Corona‐discharged tissue culture plastic served as the control. The effect of surface material was examined with regard to cell morphology; cell proliferation (cell number) and DNA synthesis ([3H]thymidine incorporation); RNA synthesis ([3H]uridine incorporation); collagenase‐digestible protein, noncollagenase‐digestible protein, and percentage of collagen production; and alkaline phosphatase‐specific activity, both in the cell layer and in trypsinized chondrocytes. Cell morphology was dependent on surface material; only cells cultured on titanium had an appearance similar to that of cells cultured on plastic. While titanium or titanium dioxide surfaces had no effect on cell number or [3H]thymidine incorporation, aluminum oxide, calcium phosphate, and zirconium oxide surfaces inhibited both parameters. Cells cultured on aluminum oxide, calcium phosphate, zirconium oxide, and titanium dioxide exhibited decreased collagenase‐digestible protein, noncollagenase‐digestible protein, and percentage of collagen production, but [3H]uridine incorporation was decreased only in those chondrocytes cultured on aluminum oxide, calcium phosphate, or zirconium oxide. Chondrocytes cultured on titanium had greater alkaline phosphatase‐specific activity than did cells cultured on plastic, but the incorporation of [3H]uridine and production of collagenase‐digestible protein, noncollagenase‐digestible protein, and percentage of collagen was comparable. The response of chrondrocytes from the growth zone and resting zone to culture surface was comparable, differing primarily in magnitude. Cell maturation‐dependent effects were evident when enzyme activity in trypsinized and scraped cells was compared. These results indicate that different surface materials affect chondrocyte metabolism and phenotypic expression in vitro and suggest that implant materials may modulate the phenotypic expression of cells in vivo.
Influence of exogenous growth factors on the expression of plasminogen activators and plasminogen activator inhibitors by cells isolated from normal and healing rabbit ligaments
Authors: Murphy Patricia G. , Hart David A. 
Published: February 2005

AbstractIn this investigation, we demonstrate that cells from normal and healing rabbit ligaments are selective in their responsiveness to various growth factors. The cells analyzed included fibroblasts isolated from the synovium, the anterior cruciate ligament, and the medial collateral ligament (midsubstance and epiligament). Fibroblasts isolated from scar tissue of medial collateral ligament that had been allowed to heal for 3 weeks also were analyzed. The addition of insulin‐like growth factor‐2 or transforming growth factor‐β1 was observed to alter, in a dose‐dependent manner, the expression of plasminogen activator and plasminogen activator inhibitor by connective tissue cells. However, the response to these growth factors was cell specific. Fibroblasts isolated from the midsubstance, epiligament, and scar tissue of the medial collateral ligament were responsive to these growth factors; fibroblasts isolated from the anterior cruciate ligament and synovium did not have a detectable response. The cells from the normal and healing medial collateral ligament responded to both growth factors by increasing plasminogen activator inhibitor activity. This was observed at both the protein and RNA level. In contrast, the addition of insulin‐like growth factor‐1 or acidic or basic fibroblast growth factor to cells derived from normal or healing ligament did not result in any detectable alteration of plasminogen activator or plasminogen activator inhibitor activity. These results are similar to those observed with an explant system and indicate that cells isolated from ligament tissue maintain their responsiveness to these growth factors in the absence of matrix. As the major effect of insulin‐like growth factor‐2 and transforming growth factor‐β1 on the cells tested was to increase plasminogen activator inhibitor activity, such an alteration should diminish the activity of plasminogen activator, an enzyme capable of directly and indirectly proteolyzing matrix molecules, and thus contribute to a more anabolic environment.
Effect of anterior cruciate ligament deficiency on economy of walking and jogging
Authors: McHugh Malachy P. , Spitz Amy L. , Lorei Matthew P. , Nicholas Stephen J. , Hershman Elliott B. , Gleim Gilbert W. 
Published: February 2005

AbstractThe metabolic cost of walking and jogging following injury to the anterior cruciate ligament is unknown. Economy of motion refers to the oxygen consumption for a submaximal work rate. The purpose of this study was to compare the economy of walking and jogging of an anterior cruciate ligament‐deficient population with that of a control population without orthopaedic abnormalities. Steady‐state oxygen consumption was measured in 30 patients and 98 controls while they were on a treadmill at various speeds. Deficiency of the anterior cruciate ligament was diagnosed arthroscopically. The patients also were tested for isokinetic knee extension‐flexion strength, hip flexion, and abduction and adduction strength and underwent arthrometic measurement of anterior tibial displacement. The patients had a statistically significant increase in oxygen consumption when jogging at 160.9 m/min (p = 0.007); however, there was no significant effect of anterior cruciate ligament deficiency on economy at the other speeds tested. The patients had significant deficits in strength of all muscle groups tested. Steady‐state oxygen consumption at 160.9 m/min tended to be inversely related to the deficit of strength of knee flexion (r = −0.44, p = 0.07). Arthrometric measurements and chronicity of injury were unrelated to steady‐state oxygen consumption. These data indicate that anterior cruciate ligament deficiency increases oxygen consumption during jogging. In long‐distance running, this decreased economy translates into significant additional caloric requirements, which may result in earlier fatigue.
An assay to measure adriamycin binding in osteosarcoma cells
Authors: Gebhardt Mark C. , Kusuzaki Katsuyuki , Mankin Henry J. , Springfield Dempsey S. 
Published: February 2005

AbstractAdjuvant chemotherapy is currently employed in the treatment of patients with osteosarcoma, but the drug regiments, although effective in improving disease‐free survival, are unsuccessful in 20–40% of patients and very toxic. It would be useful to know whether tumor cells are sensitive to a given drug prior to its use. To this end, we developed a method of assessing Adriamycin (doxorubicin) binding to tumor nuclei as a possible means of detecting sensitivity to the drug. Adriamycin‐sensitive murine osteosarcoma cells were used to develop the assay. The in vitro conditions (drug concentration, duration of incubation, and temperature) were optimized with use of the murine osteosarcoma cells in culture. After the cells had been incubated with Adriamycin, cell viability was determined and Adriamycin fluorescence intensity was measured with a cytofluorometer. The optimal parameters for Adriamycin binding were found to be a 30‐minute incubation in a 10 μg/ml concentration of Adriamycin at 37°C the frequency of cells that emitted Adriamycin fluorescence from the nucleus compared with the total number of livin cells reached 100% under these conditions. In a murine leukemia cell line with known sensitivity to Adriamycin, the cells emitted red fluorescence from the nucleus and cytoplasm, whereas in a resistant line the cells emitted Adriamycin fluorescence from only the cytoplasm. We demonstrated that it is possible to differentiate nuclear from cytoplasmic concentration of Adriamycin in a tumor cell with use of a fluorescent microscope and that resistant cell lines can be distinguished from sensitive cell lines by this method. Since Adriamycin acts by intercalating to DNA, its absence in the nucleus probably indicates a resistant cell. This is a rapid technique that may allow prediction of drug sensitivity at the time of diagnosis or relapse.
Evaluation of muscle force prediction models of the lumbar trunk using surface electromyography
Authors: Hughes Richard E. , Chaffin Don B. , Lavender Steven A. , Andersson Gunnar B. J. 
Published: February 2005

AbstractOptimization‐based models for prediction of muscle forces in the lumbar region of the torso are used to estimate the forces acting on spinal motion segments, especially for asymmetric tasks. The objectives of this study were to determine (a) which of four torso model formulations best predicted the electromyographic data, (b) the difference in muscular contribution to spinal compression force for the four models, and (c) the effect of using the lowest possible muscle stress bound in the model formulation. An approach for the investigation of competing optimization model formulations was developed and was illustrated with electromyographic data from static asymmetric loading conditions. This method is based on (a) the choice of experimental conditions in which models predict decidedly different muscle forces, and (b) the ability to ensure that the experimental conditions are such that the minimum number of assumptions about the force‐electromyogram relationship must be made in order to choose between competing model predictions. Of the four models analyzed, only the formulation with an objective function that was the sum of cubed muscle stresses predicted the electromyographic data acceptably. The muscular contribution to spinal compression force predicted by these models differed by as much as 160% for some experimental conditions. The use of the lowest possible muscle stress bound does not appear to predict muscle forces that are in agreement with electromyographic data.
Device for the application of a dynamic biaxially uniform and isotropic strain to a flexible cell culture membrane
Authors: Schaffer Jonathan L. , Rizen Michael , L'Italien Gilbert J. , Benbrahim Aziz , Megerman Joseph , Gerstenfeld Louis C. , Gray Martha L. 
Published: February 2005

AbstractA large number of studies have demonstrated that mechanical perturbation modulates cellular metabolism; however, the systematic characterization of the molecular and cellular transduction mechanisms underlying mechanically induced metabolic modulation has been impeded, in part, by the limitations of the mechanical device. The objective of this investigation was to develop an in vitro experimental system that would provide independent control of the spatial and temporal biaxial strain distribution imposed on a flexible transparent tissue culture membrane that permits attachment, proliferation, and maintenance of the phenotypic expression of cultured embryonic osteoblasts. Such a device would permit a systematic investigation of the cellular response to specific, independently controlled parameters of mechanical deformation. Using a prototype device designed to impose a dynamic sinusoidal spatially isotropic biaxial strain profile, we confirmed experimentally that the strain was biaxially uniform and isotropic (radial = circumferential strain over the entire culture membrane) to within 14% (SD/mean) for the range of the peak strains tested (2.3–9.4%). Additionally, the uniformity was maintained at 1 Hz for at least 5 days of continuous operation. This experimental verfication of the theoretically predicted isotropic strain profile suggests that the design principle is sound. Embryonic osteoblasts cultured on the flexible substrate proliferated and exhibited a temporal pattern of phenotypic expression (extracellular matrix accumulation and mineralization) comparable with that observed on polystyrene of tissue culture grade.
Technique for producing controlled closed fractures in a rabbit model
Authors: Park Sang‐Hyun , Cassim Ahmed , Llinas Adolfo , McKellop Harry A. , Sarmiento Augusto 
Published: February 2005

AbstractWe describe a new technique to produce a closed fracture of the rabbit tibia with reproducible location and shape of the fracture. The hindlimb of a New Zealand White rabbit was enclosed in a bivalved cast, a 1.5 mm diameter hole was drilled through the lateral tibial cortex, and the tibia was fractured by loading in three‐point bending in an arbor press. The cast protected the soft tissues from being crushed while it concentrated the bending moment at the intended fracture site. The cortical hole functioned as a stress riser and fracture initiation site, such that the influence of the loading rate on the fracture characteristics was minimized. Transverse fractures or oblique fractures at any desired angle could be produced by variations of the position of the cortical drill hole relative to the central loading point. Thirty‐four tibial fractures (18 transverse and 16 oblique) were produced. The rabbits were killed immediately, and the fracture angle and the extent of tissue damage were evaluated radiographically, as well as macroscopically. This method produced a consistent location of the fracture, with 88% reproducibility of the fracture angle and only minor damage to the adjacent soft tissue.
Mechanical evaluation of six types of reconstruction following 25, 50, and 75% resection of the proximal femur
Authors: Kohles Sean S. , Markel Mark D. , Rock Michael G. , Chao Edmund Y. S. , Vanderby Ray 
Published: February 2005

AbstractThe structural stiffness and the stiffness of the osteotomy site after six types of reconstruction of the proximal femur were compared by testing in axial compression, mediolateral bending, and axial torsion in a canine model. An osteotomy was carried out for 25, 50, or 75% of the length of each femur, and the proximal portion was replaced by one of five allograft/endoprosthetic composites or a segmental replacement. The reconstructions included (a) a composite press‐fit proximally and cemented distally, (b) a composite cemented proximally and distally, (c) a composite cemented proximally and fixed with two plates at the allograft‐host bone interface, (d) a composite cemented proximally and secured distally with bicortical screws, (e) a composite secured proximally and distally with bicortical screws, and (f) a segmental prosthesis cemented into the distal femur. The results showed that the segmental reconstruction and the reconstruction with double‐plate fixation and a cemented endoprosthesis were structurally stiffer and had greater stiffness of the osteotomy site than the other reconstructions. In comparison, reconstructions that involved cement alone or cement and press‐fit techniques generally were more compliant than the others, both structurally and at the osteotomy site.
Method for the measurement of friction between tendon and pulley
Authors: Uchiyama S. , Coert J. H. , Berglund L. , Amadio P. C. , An K.‐N. 
Published: February 2005

AbstractAn experimental system was developed that allows direct measurement of friction at the tendon‐pulley interface, and the results were interpreted by use of a theoretical model for friction of a cable around a fixed pulley. Validation experiments were conducted with a nylon cable around a nylon rod. One end of the cable was connected to an actuator via a load cell, and the other end was connected to a 4.9 N load via a similar load cell. The cable was passed around the nylon rod and then pulled toward the actuator. Tests were performed at five different arcs of contact. The friction forces, as measured by the difference between two load transducers, were compared with those determined for a theoretical model and were used for calculation of the friction coefficient. The measurement system then was used to study the friction force between the flexor digitorum profundus tendon and the A2 pulley on nine fresh frozen index digits. The method allows us to measure the direct interaction between the tendon and pulley and could be used to evaluate and compare procedures for tendon‐pulley and pulley repair and reconstruction, as well as for the study of tendon‐pulley friction in various pathological conditions.
Tibial intercalary allograft incorporation: Comparison of fixation with locked intramedullary nail and dynamic compression plate
Authors: Muir Peter , Johnson Kenneth A. 
Published: February 2005

AbstractThe healing and incorporation of intercalary cortical bone allografts stabilized with locked intramedullary nails was compared with that of allografts fixed with compression plates in a sheep model. Both techniques achieved healing of the allograft to host tibia, and there was no measurable difference in the area of callus or the quality of union histologically. Incorporation of the allograft as measured by fluorescent labeling was not different in the two groups.
Dimensional growth and extracellular matrix accumulation by neonatal rat mandibular condyles in long‐term culture
Authors: Garcia A. Minerva , Gray Martha L. 
Published: February 2005

AbstractMandibular condyles in organ culture commonly have been used as a model system for examination of the factors that influence skeletal growth and development. The work reported here complements previously published histological studies by providing quantitative temporal information on growth and matrix accumulation. Condyles maintained for as long as 5 weeks in serum‐free and 1% serum‐supplemented culture media were found to remain viable and metabolically active as demonstrated by continued dimensional growth as well as cell and matrix accumulation. Growth occurred by a combination of cell proliferation, matrix synthesis and accumulation, and cell hypertrophy (with the latter two mechanisms dominating). Increase in tissue volume correlated directly with increased glycosaminoglycan content; both increased 7‐fold over 5 weeks. In comparison with serum‐free culture, after 35 days in medium containing 1% serum, glycosaminoglycan content was 24% lower and collagen content was 36% higher, whereas dry weight, condyle length, and DNA content were not significantly different; in addition, histological observation suggested that, for samples cultured with serum, chondrogenic phenotype had been lost from some regions. The temporal behavior for all growth parameters exhibited a transient phase 1–2 weeks in duration followed by a steady‐state period in which dimenssions and tissue constituents or content increased at a constant or near constant rate. Comparison of the rates of incorporation of [35S]sulfate with glycosaminoglycan content in serum‐free cultures suggests that the loss of glycosaminoglycan occurs only initially or is negligible; therefore, under these baseline conditions, cartilage glycosaminoglycan content reflects the biosynthetic rate. The high degree of reproducibility seen during steady‐state growth suggests that these data provide reliable baseline information and further supports the notion that this model system is useful for investigation of the effects of specific physical factors on in vitro growth and development.
Texture correlation: A method for the measurement of detailed strain distributions within trabecular bone
Authors: Bay Brian K. 
Published: February 2005

AbstractA new technique, termed texture correlation, is described for the measurement of displacement and strain patterns within samples of trabecular bone. Texture correlation is a modification of digital image correlation, a method for analysis of deformation in objects marked with random surface speckle. Instead of surface speckle, the trabecular pattern itself is used as a basis for correlation. Digitized contact radiographs of samples in unloaded and loaded states are compared by computer to determine displacements of a grid of points. Displacements are filtered with Savitsky‐Golay polynomial‐convolution filters to reduce noise, and then strain is calculated with finite element techniques. The method is conceptually similar to the manual measurement of surface markers but has numerous advantages: no marking of the sample is required, displacements are measured automatically by computer, measurement of thousands of displacements is practical, and filtering allows calculation of strain over small regions of the sample. The validity of the technique is demonstrated by comparison of strain patterns measured by texture correlation at low resolution with the same patterns measured by a surface marker technique in six samples of trabecular bone from a human femoral head. The results of texture correlation at full resolution then are presented to demonstrate the capabilities of the method.