bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron microscopic analysis of articular cartilage proteoglycan degradation by growth plate enzymes
Authors: Buckwalter Joseph A. , Ehrlich Michael G. , Armstrong Ann L. , Mankin Henry J. 
Published: February 2005

AbstractTo assess the effect of intracellular growth plate chondrocyte enzymes on proteoglycan structure, we examined enzyme‐treated articular cartilage proteoglycans and untreated articular cartilage proteoglycans with the electron microscopic monolayer technique. The untreated proteoglycan monomers ranged in length from less than 20 nm to more than 700 nm, with a mean length of 224.5 + 101.6 nm in one experiment and 224.6 + 95.7 nm in a second experiment. Incubation with growth plate enzymes reduced proteoglycan monomers to fragments with lengths that varied from less than 5 nm to 143 nm, increased the variability in monomer length, and destroyed proteoglycan aggregates. The enzyme treated monomers had an average length of 29.5 + 17.9 nm in one experiment and 35.2 + 17.0 nm in a second experiment. The smallest common fragments were 15 nm long and would be expected to contain about 15 glycosaminoglycan chains. This experiment demonstrates that enzymes extracted from growth plate chondrocytes can degrade the chondroitin sulfate‐rich region of proteoglycan monomer core proteins, produce a range of monomer fragment sizes with less than 20% of the fragments shorter than 5 nm or longer than 100 nm, increase the variability in monomer length, and degrade proteoglycan aggregates.
“Free” and “exchangeable” or “trapped” and “non‐exchangeable” water in cartilage
Authors: Maroudas A. , Schneiderman R. 
Published: February 2005

AbstractWe repeated some of our own previous experiments, as well as some of Torzilli's recent experiments (11) on which he bases his conclusions relating to a nonexchangeable “trapped water” in cartilage. We are unable to confirm Torzilli's findings. We observed partition coefficients for 3H.HO very close to unity. That both the extrafibrillar and most of the intrafibrillar water is freely exchangeable and behaves as available water towards small solutes has been independently shown (3) for other collagenous tissues. All the different permutations of partition experiments have yielded results that are fully consistent with our original picture of the very major fraction of cartilage water being free.
Magnetic resonance imaging of osteoarthritis: Correlation with gross pathology using an experimental model
Authors: Sabiston C. Paul , Adams Mark E. , Li David K. B. 
Published: February 2005

AbstractConventional radiography has several limitations in the study of osteoarthritis (OA): changes occur late, they are restricted to bone, and they do not correlate well with the patient's symptoms. Magnetic resonance imaging (MRI) can visualize with great detail the soft tissue changes in and around joints. We have obtained MR images of knees using an experimental model of OA in order to study the early changes of OA, to correlate the images with the gross patnology, and to compare MR images with radiographs. The changes on MRI correlated with the gross pathological changes as assessed by Kendall's rank correlation test as follows: meniscal changes, τ = 0.58 (p < 0.01); osteophytes, τ = 0.59 (p < 0.05); capsular fibrosis, τ = 0.55 (p < 0.05); and overall, τ = 0.68 (p < 0.001). Abnormalities were evident on MRI as early as 4 weeks after the onset of the disease, which is 8 weeks before they appear on radiographs. Thus, MRI can show changes in OA earlier than radiography can, and the images correlate with the gross pathology.
Mechanical consequences of rod contouring and residual scoliosis in sublaminar segmental instrumentation
Authors: Johnston Charles E. , Ashman Richard B. , Sherman Michael C. , Eberle Charles F. , Herndon William A. , Sullivan J. Andrew , King Andrew G. S. , Burke Stephen W. 
Published: February 2005

AbstractThe mechanical performance of contoured Luque rods in a neuromuscular model of spine deformity was examined to define an upper limit of deformity above which rod stresses would exceed the endurance limit for 316L stainless steel and therefore predict fatigue. Bovine constructs varying from 0–120° scoliosis were loaded axially, with strain recordings obtained at the apex of the curve. Relatively low loads produced enough tensile stress to contemplate implant fatigue in all except the nondeformed (0°) construct. Construct stiffness was found to decrease rapidly in spines with greater than 38° deformity. In addition, data on patients who had suffered rod fracture from four different centers were found to compare favorably with experimental observations. We conclude that the vulnerability of Luque rod constructs to implant failure, from a mechanical standpoint, is greater than is generally assumed. Cross‐linking of rods was found to increase stiffness. Methods to decrease tensile stresses in the implants and increase stiffness include external immobilization, larger diameter rods, and procedures to enhance correction.
Trauma type, age, and gender as determinants of hip fracture
Authors: Hedlund Rune , Lindgren Urban 
Published: February 2005

AbstractWe determined the trauma type of femoral neck and trochanteric fractures in men and women aged >20 years in 19, 128 fractures reported to a computerized medical information register during 1972–1981. We found that the earlier known exponential increase of fracture incidence by age started in early adulthood rather than during middle age. An age‐related increase was found for each type of injury as well, although the incidence of fractures resulting from severe trauma increased less than that of fractures associated with moderate trauma. The incidence of low‐energy fractures in men as well as in women displayed a constant increase rate with age from young adulthood on, impugning the widely held belief that the menopause is a significant risk factor for fractures. The dominating risk factor for proximal femoral fracture in adults appears to be age, irrespective of the cause of injury, with a chronological decline in bone strength as the most likely cause of the exponential increase in the fracture incidence during adult life.
Bone ingrowth into ploymer coated porous synthetic coralline hydroxyapatite
Authors: Tencer A. F. , Woodard P. L. , Swenson J. , Brown K. L. 
Published: February 2005

AbstractPorous hydroxyapatite, converted hydrothermally from the calcium carbon exoskeleton of the coral genus Goniopora (CHAG), has been shown to be effective as a scaffold for bone ingrowth (2,3,5–7,9). However, the large pores in the material resulted in low compressive strengths. In a previous study, we found that microcoating the interal surfaces of CHAG with dilactic‐polylactic acid (DL‐PLA) improved significantly its compressive properties. The objective of this study was to determine the effect of PLA microcoating on bone ingrowth into CHAG plugs. Plugs of thick‐(3:1 chloroform to DL‐PLA by weight), medium‐ (10:1), and thin‐ (30:1) coated as well as uncoated CHAG were implanted transcortically in the proximal third of the diaphysis of the rabbit tibia. Specimens were harvested at 3, 12, and 24 weeks for mechanical testing and contralaterally for histological and histomorphometric assessment. At 12 weeks, uncoated CHAG plugs developed an average ultimate interface shear stress of 26.7 MPa, compared with 17 MPa for 30:1 and 8 MPa for 10:1 and 3:1 coated specimens. At 24 weeks, there were no significant difference in shear stress among any of the specimens. Histomorphometric assessments showed that the ratio of area fractions of new bone to area fractions of new bone and void space increased from 68–70% for 3:1 and 10:1 coated specimens at 3 weeks, and to 85.5–89.5% at 24 weeks. In comparison, uncoated and 30:1 specimens had area fraction ratios of about 82% at 3 weeks and 93% at 24 weeks. Histologic sections demonstrated direct apposition of new bone to both the coating and the hydroxyapatite as well as degradation of the coating.
Lumbar trunk muscle use in standing isometric heavy exertions
Authors: Schultz Albert , Cromwell Ronita , Warwick David , Andersson Gunnar 
Published: February 2005

AbstractA study was conducted to see whether a biomechanical model previously validated for predicting the lumbar spine internal loads imposed by the performance of easy and moderately strenuous physical tasks was also adequate for predicting loads imposed by heavy exertions. Lumbar trunk muscle myoelectric activities were measured in 10 healthy young adult men performing a variety of less strenuous and more strenuous tasks while standing upright, and these were compared to the lumbar muscle contraction magnitudes predicted by the model. For the less strenuous tasks, measured activities and predicted forces showed strong linear correlations, confirming the validity of the model at those load levels. Model predictions for the more strenuous tasks were often found to be inadequate. Contrary to model‐incorporated assumptions, substantial antagonistic muscle contractions sometimes occurred, intraabdominal pressurization may sometimes have contributed substantially to the maintenance of structural equilibrium, and the ligamentous tissues of the trunk seemed sometimes to develop substantial passive resistances to bending and twisting moments.
The response of the canine intervertebral disc to immobilization produced by spinal arthrodesis is dependent on constitutional factors
Authors: Cole Tak‐Chun , Ghosh Peter , Hannan Neil J. , Taylor Thomas K. F. , Bellenger Christopher R. 
Published: February 2005

AbstractPosterior lumbar spinal fusion was performed on five mature greyhounds. Two months prior to death, all of the surgical and five age‐matched control greyhounds were given Na235SO4(1.0mCi/kg) intravenously. All fusion animals were killed 6 months postoperation, and discs beneath the fusion mass as well as those adjacent to it (parafusion discs) were sampled separately and dissected into the nuclei pulposi and annuli fibrosi (AF). Proteoglycans (PGs) were extracted with 4.0M GuHCI and then purified by CsCI density gradient ultracentrifugation. These PG monomers were subjected to Sepharose CL‐2B chromatography, and their hydrodynamic size and ability to aggregate were determined. The level, extractability, and hydrodynamic size of PGs in the AF of fusion discs were found to be greater than those in control discs, as were the keratan sulfate core protein complexes prepared by chondroitin ABC lyase digestion. The ability of the 60‐day‐old PG subunit populations, isolated from fusion discs, to aggregate was also higher than controls. There was, however, no difference between the galactosamine/glucosamine, galactosamine/protein, glucosamine/protein, or hexuronate/protein ratios of PGs in fusion and control discs.
Electromyographic analysis of muscles across the elbow joint
Authors: Funk D. A. , An K. N. , Morrey B. F. , Daube J. R. 
Published: February 2005

AbstractAn electromyographic (EMG) technique was developed to study simultaneously the eight major elbow muscles in five normal subjects. Recordings of EMG activity in elbow muscles were obtained while the elbow joint was subjected to resisted flexion, extension, abduction, and adduction functions. The results indicate that activity in the the major elbow muscles is determined by the size of the resultant flexion and extension moments created about the elbow joint, but not by varus and valgus moments. These results support the hypothesis that determination of muscle force about a joint depends on joint constraint, namely, the degree of freedom, the resultant joint forces and moments due to externally applied load, and also the function of the muscle, i.e., the line of action of the muscle that crosses the joint. The data may be used to further refine the calculation of muscle force distribution across the elbow joint.
Contact finite element stress analysis of porous ingrowth acetabular cup implantation, ingrowth, and loosening
Authors: Rapperport D. J. , Carter D. R. , Schurman D. J. 
Published: February 2005

AbstractTwo‐dimensional linear and contact finite element analyses were conducted of total hip arthroplasty using metal‐backed, porous ingrowth acetabular components. The stress transmission characteristics from the component to the surrounding bone were given special attention. Resultant loads of 20 and 40° medial of vertical were studied, and the influence of adding a metal flange to the rim of the cup was evaluated. The results indicated that when a conventional metal‐backed component (without a flange) is initially implanted and subjected to normal loading, these components may experience distraction between the component and the surrounding bone at inferior sites. Compressive stresses in the superior dome cancellous bone, however, will be substantial. If complete porous ingrowth is achieved, the superior dome compressive stresses will be reduced and substantial shear stresses created. In addition, high local bone stresses were found at the component rim. If bone ingrowth is achieved only in specific locations, stress transmission will be dictated by those locations and may differ markedly from the case of complete bone ingrowth. In the event that no porous ingrowth is achieved and a fibrous layer forms around the component, the interface stresses will be similar to those calculated for the natural hip. The addition of a flange to the rim of the cup will reduce the magnitude of the radial stresses transmitted to the cancellous bone superiorly and medially by directly transferring some of the load to the lateral wall of the pelvis. The flange will also help to relieve the high local stresses that are found at the component rim.
Effect of peripheral nerve on limb development
Authors: Dietz Frederick R. 
Published: February 2005

AbstractThe effect of peripheral nerve on limb growth and maturation has received little attention after the limb differentiation stage. This study used an amphibian model (Rana pipiens) to examine the effect of temporary denervation on the development of limb muscle and bone tissues. Quantitative microscopic techniques were employed to evaluate bone and muscle size and cellularity between denervated and control limbs. A 15% decrease in tibial length and a 17% decrease in cross‐sectional area were foound in the temporarily denervated limbs as compared with the control limbs during the growing period studied. A 26% increase in tibial osteocyte density was found in the denervated limbs, although total osteocyte number was the same. The same differences were found on comparing less and more mature limbs from normal animals. Gastrocnemius muscle from temporarily denervated limbs had a 46% lesser cross‐sectional surface area and a 66% greater muscle fiber density as compared with control limbs. Total muscle fiber number was the same. Similar findings were observed comparing limbs of different maturities from normal unoperated animals. This study suggests that the absence of peripheral nerves decreases the rate of bone maturation, which effect may be responsible for the diminished size of denervated limbs. This work demonstrates a model for regional growth disturbances that may aid in understanding such disorders as idiopathic leg length discrepancy, hemihypertrophy, clubfoot, and the limb deformities created by paralytic diseases.
Bone mineral in the castrated rat model of osteopenia
Authors: Grynpas M. D. , Simmons E. D. , Carnes D. , Gundberg C. , Pritzker K. P. H. 
Published: February 2005

AbstractThe effects of castration on cortical bone structure and chemistry were studied in male Wistar rats of two age groups, 8 and 24 months. Some rats were castrated and some were sham operated (control) in each group. All animals were killed after 4 months. Although no changes in serum chemistry, bone chemistry, or bone histology could be found, the young castrated animals versus controls showed less density of bone mineral as determined by the density fractionation technique and smaller crystallite size of mineral particles as determined by x‐ray diffraction line‐broadening analysis. These changes, indicative of less mature bone formation, were not observed in mature castrated or control rats despite a decreased amount of bone compared with young rats. In this model, castration appears to affect bone mineral quality in young but not in old animals.
Apparent absence of local response to bone screws in guinea pigs with contact sensitivity
Authors: Lewin J. , Lindgren J. U. , Wahlberg J. E. 
Published: February 2005

AbstractGuinea pigs sensitized to nickel, cobalt, or chromium were used to study if impaired fixation occurred as a result of allergy against metal implants in bone. Screws made from stainless‐steel (ASTM F55, F138–139) or cobalt chromium (ASTM F75–76) were inserted in the right and left proximal tibiae, and the mechanical strength of the fixation to the bone was evaluated after 4 months. In addition, we studied the histology on decalcified sections of the implant bone interface from the distal femur where the same type of screws had been inserted. To see if changes in bone density occurred in the proximal tibia as a result of allergy, the amount of ash was determined. Although the animals maintained their contact sensitivity throughout the experimental period, there were no differences between allergic and control animals for any of the parameters studied. All screws were well fixed in the tibia at the end of the experiment, and histologically we did not find any significant differences between allergic and control animals by qualitative examination. The experiment supports our earlier results from a 6‐week experiment and indicates that contact allergy may be unimportant for the fate of orthopedic implants.
The effect of cryopreservation on canine menisci: A biochemical, morphologic, and biomechanical evaluation
Authors: Arnoczky Steven P. , McDevitt Cahir A. , Schmidt Mary Beth , Mow Van C. , Warren Russell F. 
Published: February 2005

AbstractThis study evaluated the effect of cryopreservation on the structural organization, biosynthetic activity, and material properties of canine menisci. The menisci were cryopreserved by incubating them in a 4% solution of dimethyl sulfoxide (DMSO) in physiologic media and freezing them to −100°C using a controlled rate freezing system. The menisci were then stored for varying periods of time from zero to 12 weeks in liquid nitrogen (−196°C). Following rapid thawing, changes in the histological appearance and biosynthetic activity of the menisci were evaluated as functions of storage time. In addition, the effects of the cryopreservation process on the tensile strength and modulus of the meniscal tissue were assessed. Although cryopreservation and short‐term storage did not appear to affect the morphological appearance or biomechanical character of the menisci, biosynthetic activity, as determined by Na2S35SO4 incorporation, was diminished to <50% of normal control values immediately following cryopreservation and thawing. Autoradiographic examination of these tissues revealed that only ∼ 10% of the meniscal cells were metabolically active, however, indicating that a marked increase in the metabolic activity of individual cells occurs following the freeze‐thaw cycle. Total metabolic activity continued to decline with storage time.
Serum‐free culture of rabbit meniscal fibrochondrocytes: Proliferative response
Authors: Webber Richard J. , Zitaglio Teresa , Hough Aubrey J. 
Published: February 2005

AbstractWe have formulated a serum‐free medium capable of supporting DNA synthesis in rabbit meniscal fibrochondrocytes at a level equivalent to 10% fetal bovine serum (FBS). The medium consists of a 1:1 mixture of Dulbecco's Modified Eagle's Medium and Ham's F‐12 medium supplemented with transferrin (1 μg/ml), selenium (1 pg/ml), trace metal mix (1:100), dexamethasone (100 ng/ml), insulin‐like growth factors I and II (50 ng/ml each), pituitary fibroblast growth factor (100 ng/ml), and lactalbumin hydrolysate (2 μg/ml). Endothelial cell growth supplement could be substituted for lactalbumin hydrolysate to obtain similar results. Ventrex PC‐1, a commercially available, low‐protein, serum‐free medium, was found to support proliferation of fibrochondrocytes but not as well as 10% FBS or our medium formulation. Lipid supplements, which are known to support the serum‐free growth of hyaline chondrocytes, were found to be either of no value or antagonistic for the culture of fibrochondrocytes. Likewise, vitamin E alone, progesterone, putrescine, and hydrocortisone were also without benefit in our culture system. Thecells had a more chondrocytic morphology when grown in defined medium as opposed to 10% FBS. The results of this study should now make it possible to identify and quantitate those factors necessary to affect meniscal repair by utilizing further techniques in vitro.
Degradative pathways in cultured synovial fibroblasts: Selective effects of pulsed electromagnetic fields
Authors: Murray J. Clifford , Lacy Margaret , Jackson Sylvia Fitton 
Published: February 2005

AbstractA cell culture model for studying the cytokine‐mediated degradation of connective tissue was exposed to clinically applied, low‐frequency pulsed electromagnetic fields (PEMF), and levels of collagenolytic activity, two lysosomal hydrolases, and prostaglandin E2 were measured. PEMFs reduced the release of two lysosomal enzymes by cultured rabbit synovial fibroblasts but did not affect their response to mononuclear‐cell–conditioned medium. PEMF did not alter levels of cytokine activity produced by a mixed mononuclear cell population, nor did they affect the cytokine‐mediated release of collagenase or prostaglandin E2 by synovial fibroblasts. The relevance of these findings to the clinical application of PEMF to soft‐and hard‐tissue injuries is discussed.
Strain rate and mineral content in fracture models of bone
Authors: Currey J. D. 
Published: February 2005

AbstractI reanalysed data from my previous work to determine the extent to which a model for the loading‐rate dependence of the fracture of cortical bone, put forward by Carter and Caler, fits this independently derived data set. In particular, the extent to which the generality of the model is vitiated by its ignoring the effect of mineralisation on strength was tested. The model was rather strongly corroborated. In addition, the reanalysed data show that yield strain is strongly strain‐rate dependent, but that Young's modulus is rather unvarying over physiological strain rates. The implication of this for hypotheses concerning fracture of bone are discussed.
Kinetic effects of adriamycin and bleomycin on two osteosarcoma models
Authors: Bell D. F. , Bell R. S. , Mankin H. J. , Gebhardt M. C. , Weltie F. , O'Brien T. 
Published: February 2005

AbstractAlthough chemotherapeutic drugs are frequently administered to patient with osteosarcoma, there has been little research into the effect of cytotoxic drugs on osteosarcoma cell biology. The effect of two drugs (Adriamycin and bleomycin) on cell cycle kinetics was investigated in vitro in an established line of human osteosarcoma cells and in vivo using the Dunn osteosarcoma model. The cell cycle changes were consistent with G2 arrest for both drugs in vivo and in vitro. The alteration in cell cycle distribution was correlated with inhibition of 3H‐thymidine incorporation in vitro. In vivo, the greater change in cell cycle distribution caused by Adriamycin was reflected in the increased inhibition of tumor growth found with this drug.