bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of fibronectin on articular cartilage chondrocyte proteoglycan synthesis and response to insulin‐like growth factor‐I
Authors: Martin James A, , Buckwalter Joseph A. 
Published: February 2005

AbstractFibronectin, a ubiquitous glycoprotein of the extracellular matrix, serves as a substrate for cell attachment. Binding to fibronectin through cell‐surface receptors promotes a flattened cell shape, stimulates the phosphorylation of intracellular protein, and changes the pattern of gene expression. Although fibronectin is abundant in normal articular cartilage, its effects on chondrocytes are not well understood. Proteolytic fragments of fibronectin stimulate the catabolism of matrix in articular cartilage and may promote the degeneration of cartilage in osteoarthritis; however, intact fibronectin may regulate other aspects of matrix metabolism, including matrix synthesis. To determine whether intact fibronectin affects the synthetic activity of chondrocytes, as well as to determine the responses of chondrocytes to the anabolic growth factor.insulin‐like growth factor‐I, we compared the incorporation of [35S] by articular chondrocytes of the rat culture.din the presence and absence of commercially prepared cellular fibronectin and 0, 10, or 100 ng/ml recomBinanf human insulin‐like growth factor‐I. Monolayer and alginate suspension cultures were compared to determine whether responses differed under conditions in which fibronectin promoted a flattened cell shape (monolayer culture) and under those in which cells maintained a spherical shape (alginate culture). In alginate cultures, fibronectin alone stimulated the incorporation of [35S]. Fibronectin with 10 ng/ml insulin‐like growth factor‐I had additive effects in alginate culture, producing the maximum incorporation of [35S]. In monolayer cultures, fibronectin did not stimulate incorporation and blocked stimulation by 100 ng/ml insulin‐like growth factor‐I. The cells from the monolayer culture were much less active synthetically (at all doses of the growth factor) than those culture in alginate. Thus, fibronectin enhanced proteoglycan synthesis and the response to insulin‐like growth factor‐I in alginate but inhibited the response to the growth factor in monolayers. These observations suggest intact fibronectin may contribute to the maintenance or repair of the matrix of articular cartilage by stimulating proteoglycan synthesis.
Noninvasive technique for measuring in vivo three‐dimensional carpal bone kinematics
Authors: Crisco Joseph J. , McGovern Robert D. , Wolfe Scott W. 
Published: February 2005

AbstractOur present knowledge of the three‐dimensional kinematic behavior of skeletal joints has been largely acquired with cadaveric models and use of invasive monitoring. In the wrist, the small size and complex motion of the carpal bones present a difficult challenge for implanted internal or external marker systems. This paper describes a technique for quantifying the three‐dimensional kinematics of the wrist and carpal bones in vivo using noninvasive computed tomographic imaging. An error analysis employing a cadaveric specimen suggests that noninvasive carpal kinematics can be measured with an accuracy within 2° of rotation and 1 mm of translation along a helical axis of motion. The in vivo application of this technique is illustrated with a single normal individual. Potential applications include the quantification of normal wrist motion, analysis of pathomechanics, and evaluation of surgical intervention. The technique is also applicable to other joints and imaging modalities.
Musculoskeletal function assessment: Reference values for patient and non‐patient samples
Authors: Engelberg Ruth , Martin Diane P. , Agel Julie , Swiontkowski Marc F. , Wright James 
Published: February 2005

AbstractAlthough researchers and clinicians are encouraged to use health‐status questionnaires to evaluate, monitor, and modify care, their use is hindered by the lack of reference values. Without reference values, it is difficult to interpret or evaluate questionnaire scores. In this paper, we present reference values for the Musculoskeletal Function Assessment, a 101‐item health‐status questionnaire designed and validated for patients with a broad range of musculoskeletal disorders. We describe reference values for two samples: non‐patients (n = 123) and patients with isolated extremity injuries (n = 274). For the non‐patient sample, descriptive statistics are presented by age and gender, measured at one point in time. For the patient sample, descriptive statistics are provided for seven Orthopaedic Trauma Association/AO diagnostic groups, measured at two points in time. Reference values for changes in the Musculoskeletal Function Assessment total score are described for patients 3 and 9 months and 6 and 12 months after injury. The total scores by post‐injury interval, across the diagnostic groups, are significantly better at follow‐up than at baseline (p = 0.00). Reference values for changes in total scores are also described in terms of these diagnostic groups across post‐injury intervals. Musculoskeletal Function Assessment total scores for Orthopaedic Trauma Association/AO diagnostic groups are significantly better at follow‐up than at baseline (p < 0.03). Changes in the total score are also tested for responsiveness with use of standardized response means. Large effects are demonstrated for patients completing the Musculoskeletal Function Assessment at 3 and 9 months (1.03), and small effects are demonstrated for those completing it at 6 and 12 months (0.49). Moderate and large effects are demonstrated for Orthopaedic Trauma Association/AO diagnostic groups across post‐injury intervals.
In situ expression of collagen and proteoglycan genes during development of fibrocartilage in bovine deep flexor tendon
Authors: Perez‐Castro Ana V. , Vogel Kathryn G. 
Published: February 2005

AbstractA region of fibrocartilage develops in bovine deep flexor tendon where the tissue wraps around bone and is subjected to compressive and shear forces in addition to tension. There is no fibrocartilage at this location in fetal tendon or in adjacent adult tendon that is subjected to tensional load only. We investigated the development of fibrocartilage in tendon using in situ hybridization to localize cells that express collagen and proteoglycan genes typical of either tendon or cartilage. The signal for type I collagen and decorin was high in cells throughout fetal and newborn tendon, as is expected in a growing tissue composed predominantly of type I collagen. No signal for aggrecan was seen in either fetal or newborn tendon. No hybridization with any of the probes for collagen or proteoglycan was detected in cells in the tensional region of adult tendon, indicating that the cells in this tissue are normally quiescent. However, the cells in the fibrocartilage of adult tendon displayed a high level of expression for types I and II collagen, decorin, biglycan, and aggrecan. This suggests that the fibrocartilage in adult tendon is a dynamic tissue. Expression of type IIA collagen is considered a marker of prechondrocytes. Type IIA collagen gene expression was present throughout both the tensional and compressed regions of fetal and newborn tendon but was absent in cartilaga and adult tendon. This suggests that cells located throught fetal tendon may have the capacity to develop as chondrocytes. Fibrocartilage signal was detected for type I collagen in 75% of the cells and for type II collagen in 50% of the cells at one location in adult tendon, suggesting that some cells in this tissue could have expressed mRNA for both type I and type II collagen.
Development of an extremely wear‐resistant ultra high molecular weight polythylene for total hip replacements
Authors: McKellop Harry , Shen Fu‐wen , Lu Bin , Campbell Patricia , Salovey Ronald 
Published: February 2005

AbstractOsteolysis induced by ultra high molecular weight polyethylene wear debris is one of the primary factors limiting the lifespan of total hip replacements. Crosslinking polyethylene is known to improve its wear resistance in certain industrial applications, and crosslinked polyethylene acetabular cups have shown improved wear resistance in two clinical studies. In the present study, crosslinked polyethylene cups were produced by two methods. Chemically crosslinked cups were produced by mixing a peroxide with ultra high molecular weight polyethylene powder and then molding the cups directly to shape. Radiation‐crosslinked cups were produced by exposing conventional extruded ultra high molecular weight polyethylene bar stock to gamma radiation at various doses from 3.3 to 100 Mrad (1 Mrad = 10 kGy), remelting the bars to extinguish residual free radicals (i.e., to minimize long‐term oxidation), and then machining the cups by conventional techniques. In hip‐joint simulator tests lasting as long as 5 million cycles, both types of crosslinked cups exhibited dramatically improved resistance to wear. Artificial aging of the cups by heating for 30 days in air at 80°C induced oxidation of the chemically crosslinked cups. However, a chemically crosslinked cup that was aged 2.7 years at room temperature had very little oxidation. Thus, whether substantial oxidation of chemically crosslinked polyethylene would occur at body temperature remains unclear. The radiationcrosslinked remelted cups exhibited excellent resistance to oxidation. Because crosslinking can reduce the ultimate tensile strength, fatigue strength, and elongation to failure of ultra high molecular weight polyethylene, the optimal crosslinking dose provides a balance between these physical properties and the wear resistance of the implant and might substantially reduce the incidence of wear‐induced osteolysis with total hip replacements.
Three‐dimensional knee kinematics and stability in patients with a posterior cruciate ligament tear
Authors: Jonsson Håkan , Kärrholm Johan 
Published: February 2005

AbstractThe three‐dimensional kinematics of the knee were studied from 5 months to 15 years after unilateral posterior cruciate ligament tears occurred in eight patients. All but two patients had signs of additional ligament injuries. Repeated radiostereometric examinations were conducted when the patients ascended a platform (step‐up test) and during an instrumented anterior‐posterior drawer test with the knee at 30° of flexion. No changes in knee kinematics were observed during the step‐up test, whereas increased anteriorposterior laxity (3.8–11.3 mm) was recorded for all patients. Four of the patients had an increased side‐to‐side difference (more than 2 mm) in anterior as well as posterior laxity. A rupture of the posterior cruciate ligament can be diagnosed at 30° of knee flexion, but an increase in anterior laxity can erroneously be interpreted as an injury of the anterior cruciate ligament. The unaffected kinematics of the knee suggest that factors such as joint load and congruity and muscle activity can compensate for the absent posterior cruciate ligament during static examinations.
Expression of α‐smooth muscle actin in canine intervertebal disc cells in situ and in collagen‐glycosaminoglycan matrices in vitro
Authors: Schneider T. O. , Mueller S. M. , Shortkroff S. , Spector M. 
Published: February 2005

AbstractThe objective of this study was to investigate the presence of a contractile actin isoform, α‐smooth muscle actin, in annulus fibrosus cells in situ and in two and three‐dimensional cultures. Annulus fibrosus cells were isolated from healthy adult dogs, serial passaged, and then injected into porous collagen‐glycosaminoglycan copolymers consisting of either type‐I or type‐II collagen. α‐Smooth muscle actin was detected in the cells in tissue samples and in culture by immunohistochemistry. The number of cells and glycosaminoglycan content of the matrices were determined after 1, 7, and 14 days, and the diameters of the specimens were measured every 2 days. Although few annulus fibrosus cells in vivo displayed the presence of the α‐smooth muscle actin isoform, most cells in two‐dimensional culture demonstrated this phenotype. The contractile behavior of these cells was shown by the cell‐mediated contraction of type‐I collagen‐ glycosaminoglycan scaffolds after 8 days in culture. Glycosaminoglycan production was not significantly different in the seeded type‐I matrices than in the unseeded matrices, whereas the seeded type‐II matrices had a significant increase in glycosaminoglycan production between days 1 and 14 compared with the unseeded controls. This is the first report of both the expression of the contractile α‐smooth muscle actin isoform in intervertebral disc cells and the ability of the cells to contract a collagen matrix. This finding could aid in better understanding the nature of cells in the annulus.
Cartilage induction by controlled mechanical stimulation in vivo
Authors: Tägil Magnus , Aspenberg Per 
Published: February 2005

AbstractTo study mechanical control of tissue differentiation, we designed a new version of the previously described bone conduction chamber. The bone conduction chamber consists of a cylindrical titanium chamber for implantation in the rat tibia. It has tissue ingrowth openings at one end, located subcortically, and the other end protrudes into the subcutis. The newly developed load chamber has a mobile piston so that an external compressive load can be transferred to the tissue within the chamber. Sprague‐Dawley rats had a regular bone conduction chamber implanted in one tibia and a load chamber implanted in the other. Mesenchymal tissue was allowed to grow into the chamber for 3 weeks before the mechanical loading was started. Thereafter, twice a day, 20 cycles of compressive load were applied with a frequency of 0.17 Hz to the load chamber. This was estimated to produce a compressive hydrostatic stress of 2 MPa. The chambers, harvested after 7 weeks of loading, all contained newly formed bone. The bone ingrowth distance into the chamber was decreased in the loaded specimens compared with the contralateral unloaded controls (p = 0.01). Instead, cartilage was found in the loaded chambers next to the piston. Beneath the cartilage was a dense bone plate under which a marrow cavity had formed. No cartilage was found in the unloaded controls, but the architecture of the bone and marrow cavity was similar to that of the loaded specimens. We conclude that this model allows load to be transmitted onto the ingrowing tissue and that the load parameters used cause this tissue to differentiate into cartilage close to the piston.
Hyaluronic acid‐based polymers as cell carriers for tissue‐engineered repair of bone and cartilage
Authors: Solchaga Luis A. , Dennis James E. , Goldberg Victor M. , Caplan Arnold I. 
Published: February 2005

AbstractCulture‐expanded bone marrow‐derived mesenchymal progenitor cells differentiate into chondrocytes or osteoblasts when implanted subcutaneously in vivo in combination with an appropriate delivery vehicle. This in vivo implantation technique is used to test new materials as putative delivery vehicles in skeletal tissue‐engineering models. HYAFF 11 and ACP sponges, two biomaterials based on hyaluronic acid modified by esterification of the carboxyl groups of the glucuronic acid, were tested as osteogenic or chondrogenic delivery vehicles for rabbit mesenchymal progenitor cells and compared with a well characterized porous calcium phosphate ceramic delivery vehicle. The implant materials were examined by scanning electron microscopy for differences in pore structure or cellular interactions, were quantified for their ability to bind and retain mesenchymal progenitor cells, and were examined histologically for their ability to support osteogenesis and chondrogenesis after subcutaneous implantation into nude mice. The ACP sponge bound the same number of cells as fibronectin‐coated ceramic, whereas the HYAFF 11 sponge bound 90% more. When coated with fibronectin, ACP and HYAFF 11 bound, respectively, 100 and 130% more cells than the coated ceramics. HYAFF 11 sponge composites retained their integrity after the 3 or 6‐week incubation period in the animals and were processed for histomorphometric analysis. As a result of rapid degradation or resorption in vivo, ACP sponges could not be recovered after implantation and could not be analyzed. HYAFF 11 sponges presented more area available for cell attachment and more available volume for newly formed tissue. Following loading with mesenchymal progenitor cells and implantation, the pore of the sponges contained more bone and cartilage than the pores of ceramic cubes at either time point. Thus, relative to ceramic, HYAFF 11 sponges allow incorporation of twice as many cells and produce a 30% increase in the relative amount of bone and cartilage per unit area. Hence, the hyaluronic acid‐based delivery vehicles are superior to porous calcium phosphate ceramic with respect to the number of cells loaded per unit volume of implant, and HYAFF 11 sponges are superior to the ceramics with regard to the amount of bone and cartilage formed. Additionally, hyaluronic acid‐based vehicles have the advantage of degradation/resorption characteristics that allow complete replacement of the implant with newly formed tissue.
Shear strength of the physis varies with anatomic location and is a function of modulus, inclination, and thickness
Authors: Williams John L. , Vani John N. , Eick J. David , Petersen Erik C. , Schmidt Thomas L. 
Published: February 2005

AbstractSlipped capital femoral epiphysis involves the gradual displacement of the femoral head relative to the neck. Many theories have arisen to explain this slip. Frequently cited etiological factors include increases in physeal thickness and inclination. Slipped epiphysis has been postulated to result from shear overload that causes separation through the hypertrophic cellular zone. We sought to answer the following questions: (a) Do significant regional differences in strength and stiffness exist within a given physis? (b) Are regional differences in resistance to shear related to thickness and inclination of the physis? (c) Does physeal compression cause mammillary interdigitation to begin sooner and increase the resistance to shear before, during, and after failure? (d) Does shear failure occur at displacements detectable by radiography? and (e) Does cleavage occur throughout the entire columnar zone, and do the chondrocyte columns remain intact on both sides of the cleavage plane? We prepared beam‐shaped microstructural samples from different sites of the bovine proximal tibial physis. We determined thickness, inclination, ultimate stress and strain, modulus, and strain energy density at ultimate stress as a function of location. Using scanning electron microscopy, we also examined the entire failed surface of several samples. Forty‐eight samples were tested by displacing the epiphysis end anteriorly, without axial (across the thickness) constraint; 41 were sheared while an average axial compressive stress of 0.3 MPa was applied to the physis. The posterior region had the greatest strength and stiffness, lowest physeal thickness, and steepest inclination. Compressing the plate did not increase the shear strength or tangent modulus. Ultimate strength varied inversely with thickness and increased when shearing up steeper inclinations; however, it was more strongly associated with the modulus, implying that additional factors control both strength and modulus. Scanning electron microscopy revealed that the plane of fracture differed widely between and within samples, involving all zones of the growth plate. On either side of the fracture, individual chondrocyte columns remained intact, although separated from neighboring columns.
Comparative study of normal and osteoarthritic canine synovial fluid using 500 MHz 1H magnetic resonance spectroscopy
Authors: Damyanovich A. Z. , Staples J. R. , Chan A. D. M. , Marshall K. W. 
Published: February 2005

AbstractHigh resolution 1H nuclear magnetic resonance spectroscopy has been used to investigate and compare the metabolic profiles of normal and osteoarthritic synovial fluids in a canine model of osteoarthritis. The spectra of osteoarthritic synovial fluid showed (a) increased concentiations of lactate, pyruvate, lipoproteinassociated fatty acids, and glycerol as well as the ketones hydroxybutyrate and hydroxyisobutyrate, (b) reduced levels of glucose, and (c) elevated levels of N‐acetylglycoproteins, acetate, and acetamide compared with healthy normal canine synovial fluid. An increase was also observed in the concentrations of the amino acids alanine and isoleucine. These results suggest that (a) the intaarticular environment in canine osteoarthritis is more hypoxic and acidotic than in a normal joint, (b) lipolysis may play an increasingly important role as a source of energy in osteoarthritis, and (c) the N‐acetylglycoprotein polymer component of synovial fluid (mostly hyaluronan) seems to be increasingly fragmented and degraded into acetate by way of an acetamide intermediate with progressive osteoarthritis. The observed changes in the biochemical profile of canine osteoarthritic synovial fluid may be useful in understanding alterations in joint metabolism consequent to arthritic diseases and helpful in identifying potential markers of osteoarthritis.
Accelerating bone formation and earlier healing after using demineralized bone matrix for limb lengthening in rabbits
Authors: Hagino Tetsuo , Hamada Yoshiki 
Published: February 2005

AbstractWe studied the effects of grafting with demineralized bone matrix during lengthening of the tibia in young Japanese White rabbits. The demineralized bone matrix was made from frozen cortical bone harvested from other rabbits. A 5‐mm gap was created in the tibial diaphysis by a subperiosteal osteotomy; a maximum of 20 mm (2–3 mm/day) of tibial lengthening was reached in a week with use of an external fixator. The control group of 20 rabbits did not receive an implant; the group of 21 experimental rabbits received an implant of demineralized bone matrix in the surgical gap. The control group failed to demonstrate radiographic callus 5 weeks after surgery, and nonunion was persistent after 1 year. In the group with demineralized bone matrix, new radiodensity was demonstrated within the lengthening gap at 3 weeks, with a gradual increase in bone density to 85% that of the intact tibia after 12 weeks. Bone union was seen within 1 year for all experimental animals for whom the external fixator was removed 8 weeks after the procedure. These bones showed normal bone structure histologically. The lengthening was carried out at a rapid distraction rate of 2–3 mm/day; therefore, this method allows for satisfactory bone formation at a faster rate than normal.