bluuebunny/crossref_metadata_2025_split huggingface dataset:
Increased collagenolytic activity in severed and sutured tendons following topical application of exogenous collagen in chickens
Authors: Porat S. , Nyska M. , Sofer B. , Shoshan S. 
Published: February 2005

AbstractTo verify the role of collagenase in reduction of peritendinous adhesion by topical application of exogenous collagen, the flexor tendons of 30 chickens were severed and sutured. Exogenous, native enriched collagen solution (ECS) was introduced in the tendon sheath via a polyethylene catheter. The effect of ECS on collagenolytic activity in the healing tendon was assessed 1, 2, and 3 weeks later both by determining the relative amounts of dialyzable protein and hydroxyproline and by using the collagen film collagenase assay. The results obtained indicated a significant increase in both dialyzable hydroxyproline level and collagenolytic activity in the ECS‐treated tendons as compared with the untreated controls. It is suggested that the effect of the topically applied exogenous collagen on increasing the collagenolytic activity may be directly related to previously observed increased gliding capacity of the tendons in the same experimental model.
Swelling of articular cartilage and other connective tissues: Electromechanochemical forces
Authors: Eisenberg Solomon R. , Grodzinsky Alan J. 
Published: February 2005

AbstractWe have measured the relationship between tissue swelling stress and consolidation for bovine articular cartilage and corneal stroma in uniaxial confined compression as a function of bath ionic strength. Our experimental protocol and results clearly demonstrate that two concentration‐dependent material properties are necessary to describe the chemical dependence of tissue swelling stress in uniaxial compression over the range of deformations and concentrations explored. A general electromechanochemical model for the swelling stress of charged connective tissues is developed. The model focuses on the role of charged matrix macromolecules in determining the mechanical behavior of the tissue. A constitutive relation for the swelling stress in uniaxial confined compression in formulated and the concentration dependence of the material properties of articular cartilage and corneal stroma is determined. The associated free swelling behavior of cartilage and cornea specimens is computed from these results and is found to compare favorably with data from the literature.
Degradative enzyme systems in osteoarthritic cartilage
Authors: Ehrlich Michael G. 
Published: February 2005

AbstractIn osteoarthritis, despite increased matrix synthesis, there is a reduction of both major matrix components, proteoglycan and collagen. This study suggests that this is the result of enhanced degradative activity intrinsic to the cartilage. Because osteoarthritis is a focal disease, histologic controls were used to measure the severity in different areas of the cartilage and in different specimens. Neutral proteoglycanase and collagenase were both described in human cartilage, and their levels matched the severity of the disease as did acid phosphatase, a marker of lysosomal enzyme. Articular cartilage collagenase has an inhibitor in the cartilage and has negligible activity in normal cartilage. This was found not to be a lysosomal enzyme. A model of osteoarthritis was studied and found to have the same biochemical pattern as human disease. Using this method, inhibitors of degradative enzymes were used as a treatment. The chelator of metallic cations EDTA was found to have a significant effect on reduction of degradative enzyme activity and altered the arthritic process.
Quantitative studies of the flexion‐relaxation phenomenon in the back muscles
Authors: Schultz Albert B. , Haderspeck‐Grib Karol , Sinkora Glenda , Warwick David N. 
Published: February 2005

AbstractIn quiet standing positions involving substantial trunk flexion, myoelectric activity in the back muscles diminishes to low levels. Aspects of that “flexion‐relaxation” phenomenon were explored through measurements of myoelectric activities in 11 young men during performance of 19 isometric tasks in flexed positions. Biomechanical model analyses were used to predict the internal loads imposed on the lumbar trunk structures during those performances. Flexion‐relaxation consistently occurred in quiet flexed standing, but marked increases in myoelectric activity were found on imposition of external loads in flexed positions. Increases in myoelectric activity per unit increase in back muscle contraction force increase were nearly the same as those found in upright postures. Whether or not flexion‐relaxation occurs, large trunk flexions load the spine heavily.
Age‐related changes in articular cartilage proteoglycans: Electron microscopic studies
Authors: Buckwalter Joseph A. , Kuettner Klaus E. , Thonar Eugene J‐M. 
Published: February 2005

AbstractBiochemical and biophysical studies have demonstrated that proteoglycan monomers from immature and adult articular cartilage differ in composition and size. To investigate the structural basis of age‐related differences in articular cartilage proteoglycan monomers and aggregates, we isolated and purified high buoyant density proteoglycans from the articular cartilages of 2‐ to 3‐month‐old calves and 18‐month‐old steers. The molecular architecture and dimensions of the proteoglycans were examined using the electron microscope monolayer method. Aggregated and nonaggregated monomers from calf cartilage were longer and less variable in length than the corresponding monomers from steer articular cartilage. Calf monomer lengths had unimodal frequency distributions whereas nonaggregated steer monomer lengths had a bimodal distribution. These observations were confirmed by acrylamide‐agarose electrophoresis, which demonstrated that the samples contained only one species of proteoglycan monomer in calf but two species in steer. In addition, calf aggregated monomers had longer thin segments indicating that calf and steer monomers differed in structure as well as in size. Steer proteoglycan aggregates were shorter and had fewer monomers than those from calf. These observations demonstrate the existence of significant age‐related structural differences in articular cartilage proteoglycans and form the basis for future study of the mechanisms responsible for these differences.
Altered orientation of glycosaminoglycans and cellular changes in the tibial cartilage in the first two weeks of experimental canine osteoarthritis
Authors: Dunham Jane , Shackleton D. R. , Nahir A. M. , Billingham M. E. J. , Bitensky Lucille , Chayen J. , Muir I. Helen 
Published: February 2005

AbstractChanges in the cellularity and in the nature of the matrix were studied in the cartilages of the tibial plateau in experimentally induced arthritis in the dog, 7 and 14 days after section of the anterior cruciate ligament. Samples from the different regions of these cartilages were chilled and sectioned in a cryostat, with a variable microtome chuck to allow precise orientation of the specimens. The samples were examined by normal light microscopy, by microscopic interferometry, and by quantitative polarized light microscopy. The orientation of the glycosaminoglycans was assessed by the new “induced birefringence” method. The results indicated that only the region of the medial tibial cartilage that was unprotected by the meniscus was affected, showing increased water content, loss of superfical cells, and a decrease in orientation of the glycosaminoglycans. Whereas the birefringence of the collagen was markedly increased: this may be a useful indicator of early osteoarthritic changes.
Effects of spinal fusion on the proteoglycans of the canine interverebral disc
Authors: Cole Tak‐Chun , Burkhardt Daniel , Ghosh Peter , Ryan Micheal , Taylor Thomas 
Published: February 2005

AbstractPosterior lumbar two‐level spinal fusion was undertaken in 10 mature beagles. The animals were sacrificed 6 and 12 months later. Two months before sacrifice control and experimental animals received intravenously Na (1 mCi/Kg). Discs encompassed by the fusion and those adjacent to it were dissected into the nucleus pulposus and annulus fibrosus (AF), which were analysed separately. Proteoglycans (PGs) were extracted with 4.0 M guanidine HCL and purified by CsCL density gradient ultracentrifugation. The hydrodynamic size and ability of the PG subunits to aggregate in the presence of hyaluronic acide were investigated by Sepharose CL‐2B chromatography. The PG subunits were analysed for their galactosamine (galN), glucosamine (glcN), hexuronic acid, and protein content or were subjected to digestion with papain or chondroitin ‐ABC‐lyase to establish the size of the chrondroitin (CS) and keratan (KS) sulphate chains and the KS‐PG core protein complex. Decreased ability to aggregate of PGs isolated from discs 6 and 12 months was generally the same or smaller than those in control tissues, the PG population present after 12 months was larger, particularly in the AF. Analysis of PG subunits from fusion discs afforded galN/glcN, galN/protein, and hexuronic acid/protein rotios that were compatible with the presence in these tissues of PGs in which the proportion of CS attached to core protein was greater than in control tissues. These. These studies provide the first experimental evidence that a metabolic response of discs in a fused segment may be accompanied by the biosynthesis of a new PG population whose structure is similar to that present in immature tissues.
Biomechanical time‐tolerance of fresh cadaveric human spine specimens
Authors: Panjabi Manohar M. , Krag Martin , Summers Donald , Videman Tapio 
Published: February 2005

AbstractChanges in the biomechanical properties of fresh cadaveric spinal specimens due to long‐term freeze storage and long test periods have been investigated. Fresh cadaveric specimens were divided into three groups: Group A specimens were tested fresh on the 1st day and 13 subsequent days; Group B specimens were tested on the 1st day, frozen in sealed bags at −18°C for 21 days, and tested for 13 consecutive days after thawing; and Group C specimens were frozen for up to 232 days and tested for 14 consecutive days after thawing. We could not find any significant differences between the behavior of the three test groups. This implies that freezing and storage, even for long periods, do not significantly alter the physical properties of cadaveric spinal specimens. Concerning the differences observed on a daily basis, the mean value of the maximum displacement for the 1st day did not differ significantly from the corresponding mean value for the 13 consecutive days. This was true for all three groups, although there was some indication that the fresh group specimens showed greater variation that the two frozen groups.
Comparative study of porous hydroxyapatite and tricalcium phosphate as bone substitute
Authors: Shimazaki Kazuhisa , Mooney Vert 
Published: February 2005

AbstractThis study was performed to quantitate the bone ingrowth and biodegradability of porous calcium phosphate. Two kinds of coralline hydroxyapatite (CHA), along with sintered triculcium phosphate (TCP), were evaluated. All implants had totally interconnecting pores. These pores measured 260–600 μ for CHA‐Goniopora (CHAG), 190–230 μm for CHA‐Porites (CHAP), and 100–300 μm fot TCP. Cylindrical implants (3 mm in diameter by 8 mm in length) were implanted into the diaphyses of rabbit tibias for 3 to 24 weeks. The quantity of regeneration bone, remaining implant, nonmineralized space, and the middle two quarters of the cortical area were measured by a computerized operator‐assisted anaylsis for bone, histomorphometry. At 3 weeks after implantation, 17.3% of CHAG, 11.3% of CHAP, and 7.0% of TCP were infiltrated by regenerated bone. At 24 weeks, 56.1% of CHAG, 52.7% of CHAP, and 44.7% of TCP were occupied by lamellar‐type bone. Implant degradation was noted to be 46.4% for TCP and 27.5% for CHAP. In contrast, CHAG did not show appreciable degradation until 24 weeks.
Fracture healing in the rabbit fibula when subjected to various capacitively coupled electrical fields
Authors: Brighton Carl T. , Hozack William J. , Brager Myles D. , Windsor Russell E. , Pollack Solomon R. , Vreslovic Edward J. , Kotwick John E. 
Published: February 2005

AbstractThe effect of capacitively coupled electrical stimulation on the healing of midshaft transverse osteotomies of the rabbit fibula is assessed roentgenographically, mechanically, and histologically. The results show that a dose‐response curve for capacitive coupling and fracture healing exists and that a 220 mV, 250 μA, 60 kHz applied electrical signal (0.33 V/cm internal electric field) is the most effective signal for fracture stimulation in this model.
Repeatability of phasic muscle activity: Performance of surface and intramuscular wire electrodes in gait analysis
Authors: Kadaba M. P. , Wootten M. E. , Gainey J. , Cochran G. V. B. 
Published: February 2005

AbstractRepeatability is an important consideration for gait analysis data that are being used as an adjunct to clinical decision making. An index of repeatability of wave forms over a number of identical cycles. The purpose of this study was to use the variance ratio to assess the repeatability of phasic muscle activity recorded with surface and bipolar imtramuscular wire electrodes during gait on 10 normal subjects. Variance ratios were calculated using rectified and smoothed elctromyographic data recorded simultaneously from the two types of electrodes. Three measures of repeatability (reproducibility, reliability, and constancy—defined as the cycle‐to‐cycle, run‐to‐run, and day‐to‐day repeatability of phasic muscle activity) were used to compare the performance of the two electrode techniques. Results show that the reproducibility and reliability were better for surface elctrodes than for intramuscular wire electrodes, and constancy was good for sufrace elctrodes and poor for intramuscular wire electrodes. Repeatability improved with increasing smoothing window lengths but was better for surface electrodes than wire electrodes, irrespective of the smoothing window. This study indicates that surface electrode data represent a more consistent measure of activity of superficial muscles, if comparisons are to be made between gait data from different test days.
Workshop on the bone‐joint implant interface
Authors: Lewis Jack L. , Galante Jorge O. 
Published: February 2005

AbstractA workshop on the bone‐implant interface, as related to loosening of total joint implants, was held in Chicago on September 14–16, 1983. More than 60 orthopaedic clinicians and researchers and basic connective tissue biologists met to review problems and potential solutions to joint implant loosening. The following is a synopsis of the presentations and discussions.
Bone grafting: Role of histocompatibility in transplantation
Authors: Goldberg Victor M. , Powell Arnold , Shaffer John W. , Zika Jocelyn , Bos Gary D. , Heiple Kingsbury G. 
Published: February 2005

AbstractThe role of histocompatibility matching in bone allografting was studied in two canine bone graft models. In a cancellous ulnar segmental replacement model, frozen bone allografts exchanged between closely matched dogs were significantly better incorporated by radiographic and histologic criteria than were strongly incompatible grafts. Frozen allograts from disparate donors in recipients receiving immunosuppression appeared indistinguishable 6 months later from those in the untreated closely matched groups and from fresh autografts. Fresh vascularized orthotopically placed fibular bone grafts were evaluated by quantitative blood flow assessment, microangiography, and fluorochrome histomorphometry. Revascularized grafts exchanged between untreated closely matched dogs demonstrated preservation of blood flow and a pattern of repair that was delayed by not otherwise different than vascularized autografts. These results suggest that fresh vascularized grafts in the Judiciously matched or immunosuppressed recipient offer attractive clinical possibilities.
Passive movement of radioactive microspheres from bone and soft tissue in an extremity
Authors: Robertson William W. , Janssen Herbert F. , Walker Robert N. 
Published: February 2005

AbstractBone biopsy is the definitive method for bone tumor diagnosis. Unfortunately, the procedure is not without risk and may substantially increase the rate and extent of tumor cell metastasis. This study used radioactive microspheres (15 μm diameter) to explore the spread of cell‐sized particles from the distal femur into the lymphatic system, venous drainage, and local tissue following a simulated biopsy in the canine model procedure. In the initial group of test animals the microspheres rapidly moved from the femur through the venous system to the lungs. There was no movement from the femur into the lymphatic system within 4 days. The lungs effectively filtered the 15μm microspheres, thus preventing arterial dissemination. Additional groups were used to explore the movement of the cell‐sized particles from the soft tissue surrounding the bone. At the end of the 4 day experimental period, microspheres were found in the iliac lymph nodes in two of nine animals. Microspheres were not detected in the lungs of any of these nine animals. These results suggest that tumor cell‐sized particles can move rapidly from the bone venous system to the lungs following a bone biopsy. It appears that the lymphatic system does not contribute to this rapid dissemination. However, the role of lymphatics in a more chronic process remains unclear.
Stress analysis of a condylar knee tibial component: Influence of metaphyseal shell properties and cement injection depth
Authors: Cheal Edward J. , Hayes Wilson C. , Lee Chong H. , Snyder Brian D. , Miller Jo 
Published: February 2005

AbstractWe generated three‐dimensional finite element models of the proximal tibia with an implanted tibial component. The component features a cobalt‐chromium tray with four short vertical posts and a porous‐coated surface for improved fixation to polymethylmethacrylate (PMMA). We examined the stresses after varying: (a) the structural rigidity of the metaphyseal cortical shell; (b) the surface area of the cobalt‐chromium tray; and (c) the depth of pressure‐injected PMMA bone cement. Our results indicate that previous finite element models of prosthetic tibial components have overestimated the structural contribution of the metaphyseal cortical shell by a factor of approximately 6. A standard size tray, in contrast to a tray that extends to the cortical shell, does not significantly alter the axial load distribution but could result in bone resorption beyond the tray periphery. An important consequence of the component peg locations is that they direct the compressive stresses into dense regions of trabeculae that run from the subchondral articular surface to the metaphyseal‐diaphyseal junction. The use of a modified von Mises failure criterion suggests that at excessive load levels the most likely location of material failure is at the bone cement–trabecular bone interface immediately distal to the fixation posts. Due to its added rigidity, injection of cement beyond the fixation posts results in slightly increased stresses in this region, but these stress increases are compensated for by an increased strength of the cementbone composite.
Effect of femoral stem length on stress raisers associated with revision hip arthroplasty
Authors: Panjabi Manohar M. , Trumble Thomas , Hult J. Erik , Southwick Wayne O. 
Published: February 2005

AbstractThe objective of this study was to experimentally determine the optimal length of a femoral component in revision total hip arthroplasty (THA). Embalmed cadaveric femurs were loaded in a physiologic manner, and strains on the lateral cortex were measured. Two kinds of defects were tested to simulate THA after removal of a nail plate and after removal of a loose femoral stem. A drill hole was made in the lateral cortex of the femur to simulate the removal of a nail plate. A reaming defect was made, using flexible reamers to thin the cortex from the lesser trochanter distally to a site corresponding to the tip of a standard femoral component, to simulate THA after removal of a previously inserted femoral stem. Femurs were tested intact, with the defects, and after insertion of femoral components with stem lengths of 100 to 250 mm. The strain increased with the creation of a defect and decreased with the insertion of an implant. For a femur with a defect, the strain was minimized when the stem length extended 1.5 femoral diameters past the defect.
Influence of cartilage conformation on its equilibrium water partition
Authors: Torzilli P. A. 
Published: February 2005

AbstractThe spatial and bulk water equilibrium partition and fluid content were determined for normal adult bovine articular cartilage as a function of pH, temperature, and geometric confinement. Water partition averaged 60 ± 7% at neutral pH and 37°C and increased with decreasing pH and increasing temperature without a concomitant change in fluid content. The variation in water partition appeared to be a result of local conformation changes in the collagen fibril ultrastructure causing a transfer between free and trapped water volume. Removal of the lateral and subchondral bone geometric constraints caused an increase in both the water partition and fluid content. However, this partiton variation could be accounted for solely from a change in free fluid volume. These results suggest that in articular cartilage the proteoglycan‐collagen interaction may be an important mechanism for controlling the partition of water between a freely exchangeable space and a space allowing no fluid exchange.
Structural changes in reassembled growth plate aggregates
Authors: Buckwalter Joseph A. , Rosenberg Lawrence 
Published: February 2005

AbstractTo investigate possible structural changes in reassembled proteoglycan aggregates during cartilage mineralization, we examined the molecular architecture and dimensions of growth plate proteoglycan aggregates by electron microscopy. The ends of fetal bovine femurs and tibias were separated into three regions: the epiphysis; the cartilage growth plate, consisting of the proliferative zone and the unmineralized portion of the hypertrophic zone; and the calcified portion of the hypertrophic zone along with part of the metaphysis. Aggregates from all three regions had the same molecular architecture. They consisted of central hyaluronic filaments with multiple attached monomers. Monomers consisted of two segments: (a) a peripheral thick segment, which represents primarily the chondroitin sulfate‐rich region, and (b) a thin segment attached directly to the hyaluronic acid filament. The length of aggregated monomers did not differ between the growth plate cartilage and the metaphysis, nor did the lengths of the thin and thick segments, indicating that the chondroitin sulfate‐rich region of aggregated monomers is not degraded during cartilage mineralization. Between the growth plate cartilage and the metaphysis, aggregates became shorter and had fewer monomers and wider spacing between monomers. These structural alterations in proteoglycan aggregates may be one of the events that prepares the matrix for mineralization.