bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative determination of joint incongruity and pressure distribution during simulated gait and cartilage thickness in the human hip joint
Authors: von Eisenhart R. , Adam C. , Steinlechner M. , Müller‐Gerbl M. , Eckstein F. 
Published: February 2005

AbstractThe objective of this study was to provide quantitative data on hip‐joint incongruity and pressure during a simulated walking cycle and on articular‐cartilage thickness in the same set of specimens. Using a casting technique in eigth specimens of the human hip (age: 18‐75 years), we determined the width of the joint space (incongruity) required at minimal load for contact at four phases of the gait cycle. The pressure distribution, measured with pressure‐sensitive film, was determined at physiologic load magnituded on the basis of in vivo measurements of hip‐joint forces. Cartilage thickness was assessed with A‐mode ultrasound. At minimal loading, the average maximum width of the joint space ranged from 1.1 to 1.5 mm in the acetabular roof, with the contact areas located ventro‐superiorly and dorso‐inferiorly throughout the gait cycle. At physiological loading, the width decreased and the contact areas covered the complete articular surface during midstance and heel‐off but not during heel‐strike or toe‐off. The pressure distribution was inhomogeneous during all phases, with average maximum pressures of 7.7 ± 1.95 MPa at midstance. The cartilage thickness varied considerably throughout the joint surfaces; maxima greater than 3 mm were found ventro‐superiorly. These data can be used to generate and validate computer models to determine the loadsharing between the interstitial fluid and the solid proteoglycan‐collagen matrix of articular cartilage, the latter being relevant for the initiation of mechanically induced cartilage degeneration.
Effects of sintered bovine bone on cell proliferation, collagen synthesis, and osteoblastic expression in MC3T3‐E1 osteoblast‐like cells
Authors: Matsumoto Takuji , Kawakami Mamoru , Kuribayashi Koichi , Takenaka Toru , Minamide Akihito , Tamaki Tetsuya 
Published: February 2005

AbstractTo determine the function of biomaterials on osteoblasts, we studied the effects of two different biomaterials, sintered bovine bone (true bone ceramic) and hydroxyapatite‐related material, on DNA and collagen synthesis and osteoblastic expression in osteoblast‐like cells in vitro. Osteoblasts cultured with true bone ceramic exhibited greater increases in DNA and collagenous protein synthesis and alkaline phosphatase activity than those cultured with hydroxyapatite. Furthermore, expression of mRNA for type‐I collagen and osteocalcin, as assessed by reverse transcription‐polymerase chain reaction, was higher in cultures grown on true bone ceramic or hydroxyapatite than in those grown with glass fragments, and levels of gene expression in true bone ceramic and hydroxyapatite cultures were at almost the same level. These findings indicate that osteoblasts cultured with true bone ceramic increase their activity, suggesting that true bone ceramic may be a more favorable substrate than hydroxyapatite for growth and differentiation of osteoblast‐like cells.
Integrin subunits responsible for adhesion of human osteoblast‐like cells to biomimetic peptide surfaces
Authors: Rezania Alireza , Healy Kevin E. 
Published: February 2005

AbstractWe have identified the integrin subunits responsible for the initial adhesion of human osteoblast‐like cells to peptide‐modified surfaces. Biomimetic peptide surfaces containing homogenous RGD (Arg‐Gly‐Asp), homogenous FHRRIKA (Phe‐His‐Arg‐Arg‐Ile‐Lys‐Ala), and a mixed ratio of FHRRIKA:RGD (25:75) were used to assess integrin‐mediated adhesion. The RGD and FHRRIKA peptides were selected from the cellbinding and putative heparin‐binding domains of bone sialoprotein. A panel of monoclonal antibodies against human α1, α2, α3, α4, α5, β1, αv, and αβ3 was used to identify the subunits most dominant in mediating short‐term (10 or 30 minutes) and long‐term (4 hours) cell adhesion to the peptide surfaces. Anti‐α2, anti‐β1, and anti‐αv significantly (p < 0.05) diminished cell attachment to homogenous RGD surfaces following 30 minutes of incubation. After 4 hours of incubation on RGD‐grafted surfaces, immunostaining of these integrin subunits revealed discrete localization of the αv subunit at the periphery of the cell (similar to focal contact points), whereas the α2 and β1 subunits stained very diffusely throughout the cell. A radial‐flow apparatus was used to determine the effect of anti‐integrin antibodies on strength of cell detachment following 10 minutes of incubation on peptide‐grafted surfaces. The strength of detachment from surfaces containing RGD was significantly reduced (p < 0.05) in the presence of anti‐α2, anti‐αv, or anti‐β1 compared with controls (presence of preimmune mouse IgG). None of the antibodies significantly influenced cell attachment to homogenous FHRRIKA‐grafted surfaces. These results demonstrate that initial (30 minutes) attachment of human osteoblast‐like cells to homogenous RGD surfaces was mediated by the collagen receptor α2β1 and the vitronectin receptor αvβ3, whereas only the vitronectin receptor governed longer term (longer than 30 minutes) adhesion (localization to focal contacts). The importance of distinct integrins in mediating the attachment of bone cells to RGD‐immobilized surfaces indicates a strategy for engineering orthopaedic implants with a built‐in surface specificity for cell adhesion.
Computer model of endochondral growth and ossification in long bones: Biological and mechanobiological influences
Authors: Stevens Sheila S. , Beaupré Gary S. , Carter Dennis R. 
Published: February 2005

AbstractEndochondral growth and ossification, the processes by which cartilage increases in size and is replaced by bone, are affected by biological factors such as intrinsic genetic makeup and systemic chemical agents. In addition, these processes are affected by epigenetic mechanical factors: they may be accelerated in regions of intermittent high shear stress and decelerated in regions of intermittent high hydrostatic pressure. Previous models of bone development have not incorporated both biological and mechanobiological influences on endochondral growth and ossification. We have implemented a finite element analysis to model a developing bone rudiment from 8 weeks of gestational development to approximately 2 years after birth. As a function of time, we calculated a maturity index that reflects the progression of a region of cartilage through the endochondral ossification sequence of proliferation, hypertrophy, mineralization, and replacement by bone. We calculated a specific growth rate for each region of cartilage and estimated overall longitudinal growth of the rudiment. Regions of cartilage replaced by bone were remodeled. The results from the maturity index can be compared with distributions of proliferative, hypertrophic, and mineralized cartilage seen on histology at various stages in development. The results of the simulation predicted prenatal and postnatal developmental events, including formation of a secondary ossific nucleus, a layer of articular cartilage, and a growth plate. Our results demonstrate the necessity to include biological and mechanobiological influences when endochondral growth and ossification are considered.
Effect of local density changes on the failure load of the proximal femur
Authors: Oden Z. Maria , Selvitelli David M. , Bouxsein Mary L. 
Published: February 2005

AbstractHip fracture among the elderly is a large and growing public health issue. Presently, all therapies approved for treatment and prevention of osteoporosis involve pharmacological agents that act systemically. In this study, we evaluated the feasibility of preventing osteoporotic hip fractures with local, rather than systemic, therapy. Our hypothesis is that local therapy to increase bone density may be as effective as systemic therapy in reducing fracture risk. Thus, the goal of this investigation was to use finite element analyses to study the effect of a localized increase in bone density on the strength of an osteopenic, human femur. Finite element predictions of the failure load were made after increasing the bone density within small regions in the proximal femur. The outcome variable from these analyses was the predicted load required to break a femur in a simulated fall to the side with impact on the greater trochanter. Increasing the density by 25% relative to baseline values in a small region (0.86 cm3) of the femoral neck increased the predicted failure load by 6.2%. The same density increase in a much larger region (4.92 cm3) increased the failure load by 15%. Inclusion of more than one region of increased density provided little additional benefit. In comparison, when the density of the entire femur was increased by 5% relative to baseline values, the predicted failure load increased by 5.4%. These findings suggest that agents capable of inducing increased bone density in small regions of the proximal femur have the potential to reduce the risk of hip fracture.
In vivo analysis of microcirculation following closed soft‐tissue injury
Authors: Schaser Klaus‐D. , Vollmar Brigitte , Menger Michael D. , Schewior Lioba , Kroppenstedt Stefan N. , Raschke Michael , Lübbe Andreas S. , Haas Norbert P. , Mittlmeier Thomas 
Published: February 2005

AbstractMajor loss of tissue is an almost invariable consequence of severe closed soft‐tissue injury. Clinically, the extent of soft‐tissue trauma determines the outcome of complex injuries and significantly influences bone healing. With use of a new animal model, this study quantitatively analyzed microcirculation, i.e., nutritive perfusion and leukocyte‐endothelial cell interaction, in skeletal muscle after standardized closed soft‐tissue injury. By means of a computer‐assisted controlled‐impact technique, a severe standardized closed soft‐tissue injury was induced in the left hindlimb of 28 rats. The rats were assigned to four experimental groups (n = 7 per group) that differed by time of analysis (1.5, 24, 72, and 120 hours after injury); rats that were not injured served as controls (n = 7). Intramuscular pressure was measured, and microcirculation in the rat extensor digitorum longus muscle was analyzed by in vivo fluorescence microscopy, which allowed assessment of microvascular diameters, functional capillary density, number of rolling and adherent leukocytes in venules, and microvascular permeability. Edema weight gain was quantified by the ratio of wet to dry weight of the extensor digitorum longus muscle. Microvascular perfusion of the skeletal muscle was characterized by a significant reduction in functional capillary density, which was paralleled by an increase in capillary diameter throughout the 120 hours of observation when compared with the controls. Traumainduced inflammatory response was reflected by a markedly increased rolling and adherence of leukocytes, primarily restricted to the endothelium of postcapillary venules; this was accompanied by increased microvascular permeability, indicative of a substantial loss of endothelial integrity. The microcirculation surrounding the core of the damaged tissue area resembled that of ischemia‐reperfusion injury in skeletal muscle, i.e., heterogeneous capillary perfusion, pronounced microvascular leakage and adherence of leukocytes. Enhanced vascular leakage and leukocyte adherence (24‐72 hours after injury) coincided with the maximum intramuscular pressure (which was not indicative of compartment syndrome) and edema formation. These results demonstrate that initial changes, leading to ultimate tissue death, after closed soft‐tissue injury are caused on the microcirculatory level. This standardized model provides further insight into microvascular pathophysiology and cellular interactions following closed soft‐tissue injury. Thus, it is an adequate tool for testing novel therapeutic interventions.
Exercise affects the mechanical properties and histological appearance of equine articular cartilage
Authors: Murray R. C. , Zhu C. F. , Goodship A. E. , Lakhani K. H. , Agrawal C. M. , Athanasiou K. A. 
Published: February 2005

AbstractDorsal carpal osteochondral injury is a major cause of reduced performance in horses undergoing high‐intensity training. It was hypothesised that the mechanical behaviour and histology of cartilage are influenced by the intensity of exercise and by location within a joint. Relationships between histology and mechanical behaviour were identified in 2‐year‐old horses undergoing 19 weeks of high‐intensity treadmill training or low‐intensity exercise and then compared between groups. Dorsal and palmar test sites were identified on radial, intermediate, and third carpal articular surfaces after euthanasia. the mechanical properties of cartilage were determined with an automated creep indentation apparatus as previously described for equine cartilage. Cartilage morphology was assessed with use of sections stained with haematoxylin and eosin and toluidine blue. Dorsal cartilage was less permeable, thinner, and had a loss of chondrocyte alignment compared with palmar cartilage. Cartilage from strenuously trained horses showed more fibrillation and chondrocyte clusters than did cartilage from gently exercised animals. Dorsal radial carpal cartilage and third carpal cartilage of strenuously trained animals were significantly less stiff than that from gently exercised animals, and the former had reduced superficial toluidine blue staining compared with that from the gently exercised group. These results indicate that topographical and exercise‐related differences exist in the morphology and mechanical properties of carpal cartilage and suggest that strenuous training may lead to deterioration of cartilage at sites with a high clinical incidence of lesions.
Effects of low oxygen concentrations and metabolic inhibitors on proteoglycan and protein synthesis rates in the intervertebral disc
Authors: Ishihara Hirokazu , Urban Jill P. G. 
Published: February 2005

AbstractThe intervertebral disc is the largest asvacular structure in the body; consequently, there are steep gradients in O2 concentration, with PO2 falling to as low as 1% O2 in the centre of the disc. We investigated the effect of O2 concentration on the rates of O2 consumption, lactate production, and sulphate and proline incorporation in bovine caudal discs. We also investigated the effects of metabolic inhibitors of energy production pathways on tracer incorporation. Samples from the outer annulus and nucleus pulposus were incubated for 24 hours in 1‐21% O2. Rates were measured during the last 4 hours of incubation. As O2 concentration was reduced from 10 to 1% O2, O2 consumption rates fell by around 75% and lactate production rates almost doubled; the bovine discs thus showed a positive progressive Pasteur effect. Incorporation rates of [3H]proline and [35S]sulphate were lowest at 1% O2. In the nucleus, but not in the outer annulus, the rate of [35S]incorporation peaked at 5% O2, where it was 30% greater than at 21% O2 and 150% greater than at 1% O2. The competitive glycolysis inhibitor 2‐deoxyglucose, the oxidative phosphorylation uncoupler 2,4‐dinitrophenol, and the oxidative phosphorylation inhibitor sodium azide all markedly reduced sulphate incorporation. These results, together with previous measurements of CO2 production rates, suggest that a functionally significant fraction of the disc 's energy is supplied by oxidative phosphorylation. However, low levels of PO2, 2,4‐dinitrophenol, and sodium azide have been reported to reduce sulphate incorporation in articular cartilage, a tissue that derives its energy almost entirely from glycolysis.
Marrow‐derived progenitor cell injections enhance new bone formation during distraction
Authors: Richards Mark , Huibregtse Barbara A. , Caplan Arnold I. , Goulet James A. , Goldstein Steven A. 
Published: February 2005

AbstractBilateral femoral distraction was performed in rats to investigate whether injections of marrow derived mesenchymal progenitor cells could be used to facilitate new bone formation. The cells were isolated from whole marrow of 2‐6‐month‐old Sprague‐Dawley rats. One‐year‐old recipient Sprague‐Dawley rats were divided into five experimental groups. Rats in groups I, II, and III received injections of mesenchymal progenitor cells on days 6 (beginning), 12 (middle), and 18 (end of distraction) after surgery, respectively. Those in group IV received injections of serum and carrier gel alone, and those in group V received no injections. Distraction zones were harvested at 36 days and analyzed for new bone volume within the distraction gap by three‐dimensional microcomputed tomography. Significant increases in new bone volume were observed for femora injected with marrow‐derived progenitor cells compared with contralateral femora and controls (no injection). The timing of the cell injections appeared to have no effect on the experimental outcome. Histologic analyses demonstrated active formation of new trabecular bone with marked osteoblastic activity and osteoid production. No qualitative differences in histologic appearances of new bone among rats in any of the five groups were seen. The results of in vitro lysis assays indicated that donor and recipient rats were not completely syngenic, leaving some doubt as to the reasons for observed increases in new bone formation. Future work will focus on attempting to repeat these experiments in a fully syngenic rat model. This rat distraction model can be used to explore the molecular and cellular behavior of these progenitor cells in a clinically relevant in vivo environment.
Evaluation of the feasibility of and results of measuring health‐status changes in patients undergoing surgical treatment for skeletal metastases
Authors: Clohisy Denis R. , Le Chap T. , Cheng Edward Y. , Dykes Daryll C. , Thompson Roby C. 
Published: February 2005

AbstractThe goal of treating patients with skeletal metastases is to decrease pain and improve or maintain physical function. Assessment of the effectiveness of treatment should therefore include evaluation of patient‐rated measures of quality of life. The primary objective of the study was to determine the feasibility of studying the effect of surgical treatment of skeletal metastases on quality of life. The secondary objective was to provide data that begin to characterize this effect. The characteristics of patients with skeletal metastases are heterogeneous, patient enrollment in the study may be low, high attrition occurs secondary to death, and well accepted health‐status measures (such as the Short Form‐36) may be ineffective at detecting changes in health status: therefore, it is difficult to study these patients. High attrition and adjuvant treatment with radiation or chemotherapy made it impractical to draw firm conclusions about the effect of surgical treatment, but a trend toward improvement in selected health‐status measures for both physical and mental health was noted. Analysis of patient‐rated health‐status scores as predictors of survival indicates that improvement in these scores 6 weeks after surgery is associated with an increase in the length of survival following surgery.
Use of roentgenography and magnetic resonance imaging to predict meniscal geometry determined with a three‐dimensional coordinate digitizing system
Authors: Haut T. L. , Hull M. L. , Howell S. M. 
Published: February 2005

AbstractTo evaluate and improve on the procedures used by a tissue bank in selecting donor menisci for transplantation, this study was designed to fulfill four objectives: (a) define and quantify a set of independent parameters for describing the geometry of the medial and lateral menisci, (b) determine how well the sizing protocol of the tissue bank (i.e., two transverse roentgenographic measurements obtained from the injured knee or six transverse magnetic resonance imaging measurements obtained from the contralateral knee) predicts the four standard transverse parameters of the menisci, (c) determine if including one additional transverse roentgenographic measurement for each compartment improves the ability of roentgenograms to predict transverse meniscal parameters, and (d) determine if five magnetic resonance imaging measurements at three different meniscal cross sections of the contralateral knee predict the 15 standard cross‐sectional parameters of the meniscus in the injured knee. A laser‐based, noncontacting three‐dimensional coordinate digitizing system was used to determine surface coordinates from which menisci were reconstructed in a computer. For each reconstructed meniscus, four parameters in the transverse plane and five cross‐sectional parameters in each of three regions (i.e., anterior, middle, and posterior) were defined, yielding a set of 19 standard parameters to describe the geometry. Through a correlation analysis, these standard parameters were shown to be largely unrelated to one another, thus confirming that the parameters form an independent set describing the three‐dimensional geometry of the menisci. The two roentgenographic measurements were poor predictors of transverse standard meniscal parameters, predicting only one of four standard parameters for the medial meniscus and none of four standard parameters for the lateral meniscus with coefficients of determination greater than on equal to 0.5. Including one additional roentgenographic measurement to the tissue bank protocol increased the number of standard transverse parameters predicted to three of four for the medial meniscus and two of four for the lateral meniscus. Magnetic resonance imaging was better than roentgenography for predicting the three‐dimensional meniscal geometry. The transverse measurements from magnetic resonance imaging predicted three of four standard transverse parameters for the medial meniscus and all four for the lateral meniscus. With the addition of the cross‐sectional measurements by magnetic resonance imaging, seven of 15 standard cross‐sectional parameters were predicted for both the medial and lateral menisci. Assuming that a successful clinical outcome depends on how well an allograft matches the size and shape of the original meniscus, magnetic resonance imaging rather than roentgenography should be used for allograft size‐matching by tissue banks.