bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rat model of distraction osteogenesis
Authors: Aronson J. , Shen X. C. , Skinner R. A. , Hogue W. R. , Badger T. M. , Lumpkin C. K. 
Published: February 2005

AbstractPrior studies of distraction osteogenesis in dog and rabbit models have shown predominantly intramembranous bone formation. Other models of fracture healing normally display mixtures of both endochondral and intramembranous bone formation. We have established a rat model of tibial lengthening that reliably reproduces the pattern of zonal osteogenesis previously observed in dog and rabbit models. A distraction rate of 0.25 mm twice a day with a 0‐day latency period produced intramembranous bone with zones of progressive mineralization from collagen. With this protocol, rats bridged the distraction gap with a 25% increase in the tibial bone length. After 20 days of distraction and 50 days of consolidation, the three‐point bending stiffness, as a percentage of the contralateral control, reached a level equivalent to that measured in the canine model for a 15% lengthening (28‐day distraction and 84‐day consolidation). Radiodensitometric analysis of the regenerate bones measured 97% of the unaffected contralateral tibial densities, and mineral analyses demonstrated that calcium and phosphorus levels in the regenerate bone reached 78% of contralateral tibial levels by day 70. We concluded that a rat model of distraction ostegenesis will be useful for a wide range of studies involving rapid intramembranous bone formation.
Stimulation of bone formation by intraosseous application of recombinant basic fibroblast growth factor in normal and ovariectomized rabbits
Authors: Nakamura Kozo , Kawaguchi Hiroshi , Aoyama Ikuo , Hanada Keigo , Hiyama Yoshiyuki , Awa Takao , Tamura Makoto , Kurokawa Takahide 
Published: February 2005

AbstractThe effect on intraosseous bone formation of a single local injection of recombinant human basic fibroblast growth factor into the distal femur was examined in normal and ovariectomized rabbits. In normal rabbits, basic fibroblast growth factor increased bone mineral density around the injected site in a dose‐dependent manner at 4 weeks, with significant effects at concentrations of 400 μg and greater. Doses of 400 and 1,600 μg of basic fibroblast growth factor increased bone mineral density by 8 and 9%, respectively, compared with the opposite control femur. Histological examination showed that basic fibroblast growth factor (400 μg) induced the proliferation or recruitment of undifferentiated mesenchymal cells around the existing trabeculae at 3 days after the injection. For the first 2 weeks, osteoid formation was strongly stimulated, and this was followed by mineral apposition for another 2 weeks, at which time the femurs were harvested. Consequently, basic fibroblast growth factor stimulated intraosseous bone formation at 4 weeks. We speculate that the direct action of basic fibroblast growth factor on bone formation may be to stimulate proliferation or recruitment of minimally differentiated mesenchymal cells and to initiate the cascade of events in later stages of bone formation. In ovariectomized rabbits, basic fibroblast growth factor (400 μg) also increased bone mineral density, histomorphometrical bone formation markers, and trabecular connectivity to levels similar to those in rabbits who had received sham operations.
Method to impact in vivo rabbit femoral cartilage with blows of quantifiable stress
Authors: Vrahas M. S. , Smith G. A. , Roseer D. M. , Baratta R. V. 
Published: February 2005

AbstractThe purpose of this study was to develop a technique by which a known stress could be applied uniformly across the femoral cartilage of a rabbit as a model for the development of post‐traumatic arthritis. A system to impact the cartilage was designed that consisted of an apparatus to deliver a blow of quantifiable force, a method to apply the stress uniformly over the impact area, and a way to accurately measure the impact area. The knee joints of cadaveric New Zealand White rabbits were surgically exposed with the knee flexed so that the distal femoral articular surface was perpendicular to an impactor. With the knee fixed in, position, a cup containing polymethylmethacrylate bone cement was applied to create an exact contour of the femoral surface, and the cement was allowed to cure. The form was then rested on the rabbit knee, and a drop tower, released a weight of known mass from a known height onto an impactor (instrumented with strain gauges to measure the compressive force) that was attached to the cup. The area of the impacted surface was determined and, with the measured force, was used to calculate an accurate estimate of the impact stress. This method can be performed under sterile conditions, and therefore it is well suited for survival experiments in which the long‐term effects of impact to cartilage will be studied.
Alterations in the mechanical behavior of the human lumbar nucleus pulposus with degeneration and aging
Authors: Iatridis James C. , Setton Lori A. , Weidenbaum Mark , Mow Van C. 
Published: February 2005

AbstractThis study tested the hypothesis that changes in the morphology and composition of the nucleus pulposus with age and degeneration have associated changes in its mechanical properties. A torsional shear experiment was used to determine viscoelastic shear properties of cylindrical samples of human nucleus pulposus with large ranges of grades of morphological degeneration (normal to severely degenerated) and ages (range: 16–88 years; average: 57 ± 21.5 years). Viscoclastic shear properties were determined from stress‐relaxation and dynamic sinusoidal tests. A linear viscoelastic law with a variable‐amplitude relaxation spectrum was used to model experimental behaviors of nucleus pulposus specimens. A statistically significant increase in the instantaneous and dynamic shear moduli was found with increasing age and grade of degeneration; the values for moduli ranged from 5.0 to 60 kPa. A significant decrease in tanδ was also detected; the values ranged from 0.43 to 0.33, indicating a decreased capacity for the nucleus pulposus to dissipate energy. The dynamic modulus and tanδ were also significantly affected by frequency. It was generally concluded that the nucleus pulposus undergoes a transition from “fluid‐like” behavior to more “solid‐like” behavior with aging and degeneration.
Characterization of regional and age‐related variations in the growth of the rabbit distal femur
Authors: Lerner Amy L. , Kuhn Janet L. 
Published: February 2005

AbstractFluorochrome labeling and microcomputed tomography were used to completely characterize the regional and age‐related variations in bone growth in the distal femur of the very young rabbit. Use of the microcomputed tomography system, in conjunction with the more routine fluorochrome labeling, allows the investigation of changes in shape that occur during development. The growth plate in the distal femur studied here is remarkable for several reasons. First, growth rates of as much as 700 μm/day were measured, a much higher rate than those typically measured in other species or in more mature animals. In addition, regional variations in bone growth rates of as much as 300 μm/day were identified in the 6‐week‐old rabbit. These variations resulted in the formation of a complex curvature in the growth plate, including four mammillary processes. Identifying the factors that regulate this type of regional variation may be especially useful in understanding the causes for angular deformities such as tibia vara or developmental dysplasias.
Acute effects of periarterial sympathectomy on the cutaneous microcirculation
Authors: Pollock David C. , Li Zhongyu , Rosencrance Eileen , Krome Jonathan , Koman L. Andrew , Smith Thomas L. 
Published: February 2005

AbstractThe clinical effects of peripheral sympathectomy on patients with vaso‐occlusive disease are often dramatic and include relief of pain, improved quality of life, and healing of ulcers. Peripheral periarterial sympathectomy is known to increase skin temperature and to maximize the nutritional component of peripheral blood flow, but the pathophysiology of vaso‐occlusive disease and the physiologic mechanisms of this treatment are unknown. In this study, the acute effects of periarterial sympathectomy were directly observed in a rabbit ear model of digital microcirculation (arterioles, arteriovenous anastomoses, and venules). The effects of periarterial sympathectomy on cutaneous perfusion and total flow were also examined using laser Doppler. Perfusion imaging and digital temperature measurements. The central auricular artery became dilated (50–100%) immediately after sympathectomy; the arterioles, arteriovenous anastomoses, and venules dilated to 165,156, and.223%, respectively, at 30 minutes and to 187,174, and 204%, respectively, at 60 minutes, relative to their baseline diameters prior to sympathectomy. Laser Doppler perfusion imaging values and ear temperatures were noted to increase after sympathectomy (8.9%, 3°C), although the core temperature of the rabbit did not change. Thus, acute periarterial sympathectomy can (a) effectively reduce the vascular tone of the distal microvasculature and (b) increase total microcirculatory perfusion—cutaneous and thermoregulatory—by both venular and arteriolar dilation. Periarterial sympathectomy has the clinical potential to increase nutritional blood flow, thereby ameliorating the signs and symptoms of ischemia associated with thermoregulatory abnormalities. Dilation of the arteriovenous anastomoses, with a subsequent reduction in vascular resistance, may contribute to the increased cutaneous temperature noted after sympathectomy.
Age‐related decline in chondrocyte response to insulin‐like growth factor‐I: The role of growth factor binding proteins
Authors: Martin James A. , Ellerbroek Shawn M. , Buckwalter Joseph A. 
Published: February 2005

AbstractThe synthetic activity of chondrocytes in articular cartilage declines with age, possibly as a result of decreased sensitivity to anabolic growth factors such as insulin‐like growth factor‐I. The sensitivity of these cells to insulin‐like growth factor‐I is regulated, in pan, by the synthesis of insulin‐like growth factor‐I binding proteins. We hypothesized that, as cartilage ages, an increase in the expression of these binding proteins suppresses the synthetic response of chondrocytes to insulin‐like growth factor‐I, To test this hypothesis, we measured proteoglycan synthesis (incorporation of [35S]sulfate per cell) in alginate cultures of chondrocytes from the articular cartilage of 1,3, 12, and 24‐month‐old rats. A dose‐response to insulin‐like growth factor‐I was determined for cells from each age group; incorporation of [35S]sulfate per cell declined with age, regardless of the dose. The sharpest decline was found between cells from the 1 and 3‐month‐old groups. Using the Western ligand b ot technique, we then compared the expression of insulin‐like growth factor‐1 binding protein in chondrocytes from the 1 and 3‐month‐old rats and found that it was increased in the cells from the older animals. Recombinant insulin‐like growth factor‐3, when added to the cell cultures of the 1‐month‐old rats, inhibited incorporation of [35S]sulfate and blocked responses to insulin‐like growth factor‐I. These findings suggest that the age‐related decline in the synthetic response of chondrocytes to insulin‐like growth factor‐I results, at least in part, from increased expression of insulin‐like growth factor binding protein.
Depth‐dependent confined compression modulus of full‐thickness bovine articular cartilage
Authors: Schinagl Robert M. , Gurskis Donnell , Chen Albert C. , Sah Robert L. 
Published: February 2005

AbstractThe objective of this study was to determine the equilibrium confined compression modulus of bovine articular cartilage as it varies with depth from the articular surface. Osteochondral samples were compressed by 8, 16, 24, and 32% of the cartilage thickness and allowed to equilibrate. Intratissue displacement within the cartilage was measured with use of fluorescently labeled chondrocyte nuclei as intrinsic, fiducial markers. Axial strain was then calculated in nine sequential 125 m̈m thick cartilage layers comprising the superficial 1,125 m̈m and in a 250 m̈mm thick layer of cartilage adjacent to the cartilage‐bone interface. Adjacent osteochondral cores were also tested in confined compression to determine the equilibrium stresses required to achieve the same levels of compression. Stress‐strain data for each layer of each sample were fit to a finite deformation stress‐strain relation to determine the equilibrium confined compression modulus in each tissue layer. The compressive modulus increased significantly with depth from the articular surface and ranged from 0.079 ± 0.039 MPa in the superficial layer to 1.14 ± 0.44 MPa in the ninth layer. The deepest layer. 250 m̈m thick, had a modulus of 2.10 ± 2.69 MPa. These moduli were markedly different from the apparent “homogeneous” modulus for full‐thickness cartilage (0.38 ± 0.12 MPa) and ranged from 21 to 560% of that value. The relatively low moduli and the compression‐induced stiffening of the superficial layers suggest that these layers greatly affect the biomechanical behavior of cartilage, such as during confined compression testing. The delineation of the depth‐dependent modulus provides a basis for detailed study of the relationship between the composition, structure, and function of cartilage in such processes as aging, repair, and degeneration.
Oxygen consumption of calvarial bone cells in vitro
Authors: Schirrmacher K. , Lauterbach S. , Bingmann D. 
Published: February 2005

AbstractTissues with tortuous and narrow diffusion pathways and cells that are remote from blood vessels nonetheless can show high metabolic activity of which the underlying bases (transport mechanisms) are not fully understood. In one such bone tissue, the O2 consumption was measured by analyzing the decrease in the partial pressure of oxygen (PO2) in a closed chamber containing calvarial fragments from adult guinea pigs (250–400 g) or from neonatal rats and guinea pigs. The O2 consumption of fragments from adult guinea pigs amounted to 0.05. 0.066, and 0.095 ml/100 g * minute at 24. 27, and 36.5°C, respectively. When the temperature exceeded 43°C, O2 consumption irreversibly stopped. Both antimycin A and rotenone, which block the respiratory chain, reduced O2 consumption to approximately 20% of control values. O2 consumption was significantly higher in neonatal animals (0.369 ml/100 g * minute at 27°C) and could be blocked completely by antimycin A. On the basis of the high consumption of O2 by bone cells. we hypothesize that specialized transport systems, i.e., gap junctions, are required to provide a sufficient supply of nutrients to cells in osseous tissue.
Selective ablation of rat knee joint innervation with injected immunotoxin: A potential new model for the study of neuropathic arthritis
Authors: Salo Paul T. , Theriault Elizabeth , Wiley R. G. 
Published: February 2005

AbstractNeuropathic arthropathy is a severe chronic degenerative condition associated with decreased or absent I sensory innervation of the involved joint. Existing animal models of neuropathic arthritis are limited by the technical difficulties of obtaining either highly selective or complete joint denervation in a minimally invasive fashion. We undertook experiments to determine the feasibility of using the newly described method of selective neuronal lesioning with injected immunotoxin as a means of creating a more tractable model of neuropathic arthritis. Retrograde tracing with fluorochrome revealed that the knee joint of the female Wistar rat is supplied by 581 ± 31 (mean ± SD) joint afferents. Immunohistochemistry confirmed that virtually all sensory neurons in the rat express the cell surface receptor Thy I. Injection of rat knee joints with an immunotoxin targeted toward Thy 1 resulted in the selective ablation of an average of 88% of the joint afferents identified with fluorochroime that are normally found in the ipsilateral L3 and L4 ganglia.
Primary immunolocalization of androgen target cells in the human anterior cruciate ligament
Authors: Hamlet Ward P. , Liu Stephen H. , Panossian Vaché , Finerman Gerald A. M. 
Published: February 2005

AbstractTo identify androgen target cells in the human anterior cruciate ligament, immunohistochemical localization of the androgen receptor was performed in 31 specimens of the ligament. All of the specimens were obtained at surgery. Seventeen specimens were from women, and 14 were from men; the average age of the patients was 45.2 years (range: 18–78 years). An immunoperoxidase method using monoclonal antibodies to the androgen receptor was employed to identity androgen target cells in the ligament. Consistent staining of the androgen receptor was demonstrable in six specimens obtained from young men 18–24 years old, and equivocal positive staining was seen in two other specimens from young men. No receptors were demonstrated by this method in any of the specimens from women or older men. Androgen receptors were localized to synoviocytes in the synovium and under the synovial lining, fibroblasts in the ligament stroma, and cells lining the blood‐vessel walls of the anterior cruciate ligament. The demonstration of androgen receptors in the cells of the anterior cruciate ligament strongly suggests that male sex hormones may have an effect on the structure and composition of this ligament in young men.
Influence of stem geometry on mechanics of cemented femoral hip components with a proximal bond
Authors: Mann Kenneth A. , Bartel Donald L. , Ayers David C. 
Published: February 2005

AbstractNonlinear, three‐dimensional, finite element models of cemented femoral hip components with a proximal stem‐Cement bond were developed with use of a Charnley stem geometry and a modified Charnley stem geometry that had a cylindrical cross section over the distal two‐thirds of the stem (Distal‐Round). Peak tensile stresses in the proximal cement mantle increased 63 and 74% for the Charnley and Distal‐Round stems, respectively, when the proximal stem‐cement interface was debonded, The shear stresses over the stem‐cement interface with a proximal bond were 29%. larger for the Distal‐Round stem than for the Charnley stem. After the proximal stem‐cement interface was debonded. the peak tensile stresses in the cement mantle were 15% larger for the Distal‐Round stem than for the Charnley stem. The results illustrate that stresses within the proximal cement mantle could be substantially reduced for both Charnley and Distal‐Round stems through use of a proximal stem‐cement bond. However, the risk of debonding may be higher for the Distal‐Round stem because of increased shear stresses, and once debonded the risk of further loosening due to failure of the cement mantle would also be higher for the Distal‐Round stem.
Laxity and flexibility of the ankle following reconstruction with the Chrisman‐Snook procedure
Authors: Tohyama Harukazu , Beynnon Bruce D. , Pope Malcolm H. , Haugh Larry D. , Renström Per A. 
Published: February 2005

AbstractThe effect of reconstruction of the anterior talofibular ligament with the Chrisman‐Snook procedure on neutral zone laxity (anterior‐posterior displacement at low loads) and flexibility (a measure of the nonlinear load‐displacement response) of the ankle was investigated in vitro during the anterior drawer test. Neutral zone laxity was defined as the magnitude of anterior‐posterior displacement of the ankle joint at ±2.5 N of applied load. The flexibility parameter was defined as the slope of a line between the natural logarithm of the anterior load applied to the ankle and the resulting displacement. After reconstruction with the Chrisman‐Snook procedure, the values for neutral zone laxity of the ankle were significantly less than normal at 0° of plantar flexion, whereas the flexibility values were significantly greater than normal. This study revealed that, after the Chrisman‐Snook procedure, values for ankle flexibility are not restored to normal even if those for neutral zone laxity are reduced to less than normal. The findings suggest that this nonanatomical reconstruction procedure does not reproduce normal kinematics of the ankle joint. This may help explain some of the adverse clinical reports associated with the Chrisman‐Snook reconstruction procedure.
Degeneration at the insertion weakens the tensile strength of the supraspinatus tendon: A comparative mechanical and histologic study of the bone‐tendon complex
Authors: Sano Hirotaka , Ishii Hirotada , Yeadon Alan , Backman David S. , Brunet Jacques A. , Uhthoff Hans K. 
Published: February 2005

AbstractThe purpose of this investigation was to determine the relationship between the degree of degeneration at the supraspinatus insertion, the tensile strength, and the site of failure of this tendon. Thirty‐three fresh cadaveric shoulders (average age: 62 years; range: 39‐83 years) were examined. A tensile load to failure was applied at a constant crosshead speed of 25.4 mm/min to a 10 mm wide strip of the supraspinatus tendon that remained attached to the bone. Preexisting degenerative changes at the insertion were assessed and scored histologically and compared with the ultimate tensile stress. Twenty tendons failed at the insertion (the insertion group), and 11 failed in the midsubstance (the midsubstanee group). The histologic score of degeneration for the insertion group was significantly higher than that for the midsubstance group (p = 0.0026). There was a negative correlation between the ultimate tensile stress at the insertion and the degeneration score for the insertion group (r = −0.60; p = 0.013). Histologic observations revealed that disruptions of tendon fibers were located mostly in the articular half of the tendon and that they enlarged during mechanical testing in 90% of the specimens of the insertion group. It seems that degenerative changes at the supraspinatus insertion reduce the tensile strength of the tendon and constitute a primary pathogenetic factor of rotator cuff tear.
Radial tensile properties of the lumbar annulus fibrosus are site and degeneration dependent
Authors: Fujita Yoshi , Duncan Neil A. , Lotz Jeffrey C. 
Published: February 2005

AbstractWe conducted an in vitro study of the radial tensile properties of the annulus fibrosus. The stress‐strain response was nonlinear, with a mean tangent modulus of 0.19 MPa at zero strain and 0.47 MPa at 70% of the yield strain. We also investigated whether these properties varied as a function of location within the disc and degree of degeneration. Specimens harvested from the middle layers of the annulus were stiffer and failed at smaller strain magnitudes than those from the inner or outer annulus (analysis of covariance, p <0.05). Differences due to degeneration were evident; degenerated discs had a 30% decrease in yield and ultimate stress compared with normal discs. Similarity between our data and those reported for the annulus in compression suggests that these values reflect the material behavior of the interlaminar matrix and are an order of magnitude smaller than values used in previous analytical representations of this tissue. We expect that awareness of these data will result in improved understanding of the physical behavior and tolerance to injury of the annulus fibrosus.