bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biosynthetic response of cartilage explants to dynamic compression
Authors: Sah Robert L.‐Y. , Kim Young‐Jo , Doong Joe‐Yuan H. , Grodzinsky Alan J. , Plass Anna H. K. , Sandy John D. 
Published: February 2005

AbstractThe biosynthetic response of calf articular cartilage explants to dynamic compression was examined over a wide range of amplitudes, waveforms, and frequencies. Glycosaminoglycan synthesis was assessed by 35S‐sulfate incorporation, and amino acid uptake and protein synthesis were assessed by 3H‐proline incorporation. Two culture chambers were designed to allow uniaxial radially unconfined compression and mechanical testing of cartilage disks: one chamber was used inside a standard incubator; the other was used with a mechanical spectrometer and allowed load and displacement to be monitored during compression. Dynamic stiffness measurements of 3‐mm diameter disks identified a characteristic frequency [0.001 Hz (cycles/sec)] that separated low‐ and high‐frequency regimes in which different flow and deformation phenomena predominated; e.g., at 0.0001–0.001 Hz, significant fluid was exuded from cartilage disks, whereas at 0.01–1 Hz, hydrostratic pressure increased within disks. At the higher frequencies, oscillatory strains of only ∼1–5% stimulated 3H‐proline and 35S‐sulfate incorporation by ∼20–40%. In contrast, at the lower frequencies (a) compressions of <5% had no effect, consistent with the dosimetry of biosynthetic inhibition by static compression (∼25% compression caused a ∼20% inhibition of radiolabel incorporation), and (b) higher amplitudes (cycling between disk thicknesses of 1.25 and 0.88–1.00 mm) stimulated 3S‐sulfate incorporation by ∼20–40%, consistent with the kinetics of response to a single 2‐h compression and release. None of the compression protocols was associated with detectable alterations in (e.g., compression‐induced depletion of) total glycosaminoglycan content. This study provides a framework for identifying both the physical and biological mechanisms by which dynamic compression can modulate chondrocyte biosynthesis. In addition, the culture and compression methodology potentially allows in vitro evaluation of clinical strategies of continuous passive motion therapy to stimulate cartilage remodeling.
The effect of low sulfate concentrations on the glycosaminoglycan synthesis in anatomically intact articular cartilage of the mouse
Authors: van der Kraan Peter M. , de Vries Bernard J. , Vitters Elly L. , van den Berg Wim B. , van de Putte Levinus B. A. 
Published: February 2005

AbstractWe have studied the effect of environmental sulfate concentration on the glycosaminoglycan synthesis of anatomically intact patellar cartilage of the mouse in vitro. Incubation of mouse patellae in medium with sulfate concentrations below 0.5 mM resulted in a diminished incorporation of sulfate but in unaltered incorporation of glucosamine. This suggested the synthesis of undersulfated glycosaminoglycans under these conditions. We characterized glycosaminoglycans synthesized at three different sulfate concentrations: a sulfate concentration physiological for the mouse (1.0 mM), a sulfate concentration in the range where sulfate incorporation was strongly diminished (0.1 mM), and an extremely low sulfate concentration (10 nM). Analysis of glycosaminoglycan disaccharides and DEAE anion chromatography of the glycosaminoglycans could not confirm the synthesis of undersulfated glycosaminoglycans at 0.1 mM. The chromatogram of glycosaminoglycans synthesized in medium containing 10 nM showed the presence of a very low sulfated glycosaminoglycan pool not observed at higher medium sulfate concentrations. Intermediately sulfated glycosaminoglycans were also synthesized during incubation with 10 nM sulfate. So, our data indicate that only very low sulfate concentrations in the medium lead to the synthesis of undersulfated glycosaminoglycans and that the sulfation mechanism of murine patellar cartilage chondrocytes does not seem to fit completely in an “all‐or‐nothing” pattern.
Cellular turnover at the chondro‐osseous junction of growth plate cartilage: Analysis by serial sections at the light microscopical level
Authors: Farnum Cornelia E. , Wilsman Norman J. 
Published: February 2005

AbstractIn the distal hypertrophic cell zone of growth plate cartilage, the penetration of metaphyseal vascular endothelial cells is into the noncalcified territorial and pericellular matrices. Cellular mechanisms that promote metaphyseal vascularization are understood poorly, partly because no study has addressed the question of the time sequence of cellular interactions at the chondro‐osseous junction. The purpose of the present study is to make predictions about the relative and the real time duration of cellular events during vascular invasion, including an analysis of the time sequence of death of the terminal hypertrophic chondrocyte. The data from serial section analysis at the light microscopical level of tetracycline‐labeled growth plates indicate that death of the terminal hypertrophic chondrocyte occurs in discrete morphological stages characterized by rapid cellular condensation followed, within minutes, by endothelial cell penetration into the vacated lacuna. Cellular condensation lasts ∼45 min or 18% of the time a cell spends as a terminal chondrocyte. The data also demonstrate that chondrocytic death occurs prior to invasion by vascular endothelial cells and that the chondrocytic lacuna remains empty for as long as 15 min before an endothelial cell or blood vascular cell fills the space.
Regeneration of growth plate cartilage induced in the neonatal rat hindlimb by reamputation
Authors: Libbin Richard M. , Rivera Maria E. 
Published: February 2005

AbstractFollowing primary hindlimb amputations dividing the lower femur or the central tibiofibula, the neonatal rat innately regenerates the distal growth plate(s) with a frequency of about 20–30%. One or two reamputation procedures were performed in an effort to increase the frequency of physeal regeneration, noting that such procedures, and related forms of tissue stimulation, have been repeatedly shown to induce regenerative growth at limb amputation sites of some amphibians that display little innate regenerative capacity. The present reamputation sequences divided the skeletal stump through the cartilaginous mass arising at its distal end. Following first reamputation an approximate three fold increase in the frequency of growth plate cartilage regeneration was observed at transfemoral and transtibiofibular sites. Only after second reamputation, however, did tibiofibular physeal cartlage regeneration equal in frequency that observed after first reamputation through the lower femur. Ectopic growth plate cell architecture was identified in cartilaginous extensions arising from the side of the distal femoral shaft, and also within the regrown secondary cartilage body, which unites the lower tibia and fibula in the shank of the rat. Moreover, among 3 of 11 femoral amputees that had sustained reamputations, regrowth of the distal femoral condylar mass and profile were achieved to varying degrees. It is concluded that a regimen of reamputation, known to induce regenerative growth in the amphibian limb, also induces skeletal regeneration in the mammalian limb, and leads to the appearance of ectopic growth plate cell architecture at adjacent sites.
Effect of hyaluronic acid/chondroitin sulfate on healing of full‐thickness tendon lacerations in rabbits
Authors: Meyers Steven A. , Seaber Anthony V. , Glisson Richard R. , Nunley James A. 
Published: February 2005

AbstractViscoat, a high‐molecular‐weight, highly purified hyaluronic acid (HA) and chondroitin sulfate (CS) compound, was instilled around rabbit plantaris tendon following full‐thickness laceration and surgical repair. After 3 weeks of immobilization, no significant difference in adhesion strength or tensile strength of the healing tendons existed between Viscoat‐treated tendons and controls. This contradicts previous studies which suggest that hyaluronic acid reduces postoperative tendon adhesions. Further studies examining tendon adhesions after less severe degrees of tendon injury and using direct, quantitative measurement techniques are warranted to demonstrate whether HA has a beneficial effect on tendon healing.
Effects of intercostal nerve resection on the longitudinal rib growth in the growing rabbit
Authors: Agadir M. , Sevastik B. , Sevastik J. A. , Svensson L. 
Published: February 2005

AbstractTwo, three, or four intercostal nerves with their vasoconstrictive sympathetic fibers were resected on the right side of 15 growing rabbits. Animals submitted to sham operations and intact animals formed two control groups. A scintigraphic study with 99mTc‐methylene diphoshonate, performed on the test group 2 months after the resection, showed a significantly greater uptake of the isotope on the right than on the left costochondral junctions (p < 0.05). Three months later the difference was still larger. There was no such significant difference in the rabbits of the two reference groups. In the rabbits of both these groups, the right and left ribs of each pair were almost equal in length. Of the denervated ribs of the rabbits composing the test group, the right ribs increased in length to a greater extent than the corresponding left ribs. The difference was statistically significant (p < 0.05). As a consequence of this left‐right difference in length, mild thoracic scoliosis convex to the left developed 2 months after the resection. The total weight and volume of the denervated right ribs increased significantly more than those of the corresponding control left ribs (p < 0.05), but their mineral content per unit of weight or volume showed no significant difference.
Temporal biomechanics of posterior cervical spine injuries in vivo in a rabbit model
Authors: Wetzel F. Todd , Panjabi Manohar M. , Pelker Richard R. 
Published: February 2005

AbstractThere are numerous clinical and biomechanical criteria for determination of acute spinal instability. No data, however, exist on the biomechanical behavior of the injured, untreated spine during the healing period. Using a rabbit model, this study was designed to quantify changes in the mechanical properties of the injured spine over time. Sixteen rabbits were assigned to four injury groups: Injury 1 (C4–5 supra/intraspinous ligament transection), Injury 2 (C4 laminectomy), or Injury 3 (C4 laminectomy, plus bilateral facet capsular ligament transection). The fourth injury group was Sham (posterior exposure of C4–5, no spinal injury). Preinjury range of motion was determined by standardized flexion‐extension radiographs on all animals. Postinjury flexion–extension radiographs were taken at 4, 8, and 12 weeks. At the end of 12 weeks, animals were killed. Mean range of motion at C4–5 for all injury groups decreased from preinjury values. The greatest decrease was for the most severe injury. At 8 weeks, the range of motion for this injury was less than half of the preinjury level and increased to 62% of the preinjury level at 12 weeks.
The effect of surface and internal electrodes on the gait of children with cerebral palsy, spastic diplegic type
Authors: Young Craig C. , Rose Sven E. , Biden Edmund N. , Wyatt Marilynn P. , Sutherland David H. 
Published: February 2005

AbstractThe purpose of this study was to determine whether surface and internal fine‐wire electromyography electrodes had an effect on gait. The subjects for the experiments were 38 children with the spastic diplegic type of cerebral palsy. The children were filmed using the high‐speed cinematographic technique while they walked (a) with no electrodes (unencumbered), (b) with only surface electrodes, and (c) with internal electrodes. Single stance time, step length, cadence, and walking velocity were compared with analysis of variance and Bonferroni t tests. The results included a significant decrease in cadence (−6.3% of unencumbered walking; p < 0.05) when comparing walking with surface electrodes with walking without any electrodes. The internal electrodes caused significant decreases from normal walking in the following parameters: step length for both the measured leg ( −18.6%; p < 0.005) and the nonmeasured leg ( −18.0%; p < 0.005), cadence ( −7.9%; p < 0.02), and walking velocity ( −23.5%; p < 0.005). Internal electrodes caused significant decreases as compared with surface electrodes in the step length for both the measured leg (15.7%; p < 0.01) and the nonmeasured leg (15.6%; p < 0.005) and walking velocity (19.7%; p < 0.005). Single stance phase did not change significantly in any of the comparisons. It appears that the addition of the surface electrode apparatus does change the normal gait of a subject, causing a large decrease in cadence. The measurement of gait with internal electrodes causes further change in gait, resulting in large decreases in step length and walking velocity. While these tests provide important and useful clinical data, physicians and researchers must realize that the gait being measured with these techniques is different from a normal gait pattern.
Density changes at the proximal tibia after medial meniscectomy
Authors: Odgaard Anders , Pedersen Claus M. , Bentzen Søren M. , Jørgensen Jørgen , Hvid Ivan 
Published: February 2005

AbstractTrabecular bone density changes at the proximal tibia were studied after total and partial meniscectomy using quantitative computerized tomography. Thirty‐seven medially meniscectomized patients (5‐and 10‐year followup) and 10 control persons were included. In the partially and the totally meniscectomized knees, the area of maximal density in the medial tibial condyle was displaced ∼4 mm in a posteromedial direction relative to the position in the intact knees. In both partially and totally meniscectomized knees, the density in the region of tibiofemoral contact in the medial tibial condyle was higher compared with the density in the same region in the contralateral intact knees. This difference was of the same order in the 5‐ and 10‐year follow‐up groups. The density difference between the meniscectomized and the intact knees in the region of tibiofemoral contact in the medial condyle was significantly higher in totally than in partially meniscectomized patients. It is concluded that not only total but also partial medial meniscectomy is followed by density changes, occurring within the first 5 years after meniscectomy. The results emphasize the importance of the utmost conservatism in surgery on the meniscus.
Effects of elevation on nerve function in an acute upper extremity nerve compression model
Authors: Chidgey Larry K. , Szabo Robert M. , Kolack Barbara 
Published: February 2005

AbstractExternal compression was applied to the palmar surface of the wrist over the carpal tunnel in eight healthy volunteer subjects. With the arm in the maximum elevated position, the carpal tunnel pressure was elevated to 50 mm Hg, being continuously monitored by a slit catheter inserted into the carpal canal. Sensory and motor latencies and amplitudes were evaluated at 1‐min intervals. When the sensory amplitude decreased by 50% (correlating with subjective sensory changes), the hand was lowered to heart level, still maintaining the carpal tunnel pressure at 50 mm Hg. Nerve conduction velocity and amplitude monitoring continued at 30‐s intervals until complete sensory block. Four subjects demonstrated a transient reversal in the sensory amplitude decline with lowering of the hand to heart level, but soon progressed to a complete sensory block. The remaining four subjects demonstrated no change in the sensory amplitude decline with lowering of the hand to heart level. Our results suggest that with moderately elevated carpal tunnel pressures, once the sensory amplitude drops by 50% and the patient starts experiencing subjective sensory changes, lowering the hand to heart level may not change the local tissue blood flow sufficiently to maintain a sustained reversal in the declining nerve function and impending nerve damage.
Neutral protein‐degrading enzymes in experimental fracture callus: A preliminary report
Authors: Einhorn Thomas A. , Hirschman Albert , Kaplan Charles , Nashed Rafat , Devlin Vincent J. , Warman Jeffrey 
Published: February 2005

AbstractThe process of endochondral fracture healing is biochemically similar to growth plate calcification. Recent studies have identified potentially important roles for proteoglycan‐degrading enzymes in the growth plate. The purpose of the study described herein was to identify, in healing fractures, neutral enzyme activities capable of degrading proteoglycans and other matrix proteins. Two sets of 60 male Sprague‐Dawley rats underwent the production of closed femoral fractures. Calluses were retrieved at timed intervals, and cell and matrix vesicle fractions were prepared for electron microscopy, neutral peptidase, and alkaline phosphatase assays. In another group of 10 animals, fractions were prepared from 14‐day calluses and examined for proteoglycanase activity. In the cell fractions, alkaline phosphatase, alanyl‐β‐naphthylamidase, aminopeptidase, and endopeptidase activities showed somewhat parallel distributions peaking at ∼14–17 days. In the matrix vesicle fractions, similar relative distributions were observed for alkaline phosphatase and endopeptidase. However, here the peak activities occurred up to 3 days later than they did in the cell fractions. Significant proteoglycanase activity was confirmed in both cell and matrix vesicle fractions. These findings are consistent with the hypotheses that (a) neutral peptidases, by virtue of their temporal expression in parallel with alkaline phosphatase, may be involved in preparing fracture callus matrix for calcification; and (b) matrix vesicles may convey certain of these enzymes to sites of both matrix degradation and calcification, since the same activities found in cells are found in matrix vesicles a few days later. The possibility that some of these enzymes are involved in growth factor activation remains to be investigated.
Structural consequences of endosteal metastatic lesions in long bones
Authors: Hipp J. A. , McBroom R. J. , Cheal E. J. , Hayes W. C. 
Published: February 2005

AbstractLytic metastatic lesions from breast, prostate, and other cancers often develop on the endosteal surface of a long bone without penetrating the cortical wall. Current clinical guidelines for determining the fracture risk associated with these endosteal defects do not account for the structural consequences of the lesion. We undertook a combined experimental and analytical study of the structural consequences of the lesions with the ultimate goal of providing improved fracture risk guidelines. Endosteal defects of variable length and involving a variable amount of the cortical wall were created with an expanding reamer in canine femurs. The contralateral femur served as a control. The femurs were tested to failure in four point bending. The geometry of the experimental defects was determined from radiographs and CT. Finite element models of the canine femurs were then used to examine geometric and material parameters in both four point bending and in torsion. The experimental data demonstrate a linear relation between bone strength and amount of cortical wall remaining: % intact strength = 99.6 × remaining wall thickness −2.0, R2 = 0.769, standard deviation of regression = 11.57. Four of five data points from the linear finite element models were within the 95% confidence intervals for the experimental data. Experimental and finite element data suggest that the minimum wall thickness is the most critical geometric parameter for predicting the structural consequences of endosteal defects. The length of the defect along the bones' long axis has little effect on bone strength. The length of the defect along the bones' long axis has little effect on bone strength. The anelastic behavior of bone does not need to be represented in finite element models of simple endosteal defects because the defects do not cause significant stress concentrations. However, reduction in the modulus of bone along the border of a defect (due to osteolytic changes) can significantly reduce bone strength. These results indicate that the minimum wall thickness should be determined when clinically evaluating an endosteal defect. The results also suggest that information on bone porosity around metastatic lesions should be considered when making estimates of bone strength.
Cancellous bone material properties in osteoarthritic and rheumatoid total knee patients
Authors: Wixson Richard L. , Elasky Neal , Lewis Jack 
Published: February 2005

AbstractOne hundred and thirty‐four cancellous bone biopsy specimens were takne from the proximal tibias and distal femurs of 55 patients undergoing total knee replacement for analysis of their area fraction and mechanical testing to determine their strength and stiffness. The purpose of the study was to measure the material properties of cancellous bone taken from arthritic patients and compare these with bone from normal subjects. The results showed a wide variation of strength (0.5–18.1 MPa, mean 5.6 MPa) and stiffness (11–504 MPa, mean 152 MPa). These values are in the same range or less than those reported for bone from normal tibias.
Bone ingrowth into the tibial component of a canine total condylar knee replacement prosthesis
Authors: Turner Thomas M. , Urban Robert M. , Sumner Dale R. , Skipor Anastasia K. , Galante Jorge O. 
Published: February 2005

AbstractThe purpose of this study was to evaluate the occurrence of bone ingrowth in a porous coated tibial component of a canine total condylar design knee replacement model. The entire undersurface of the tibial prosthesis was covered by a titanium fiber metal porous composite pad. Projecting from this surface were three short, cylindrical, fiber metal coated pegs that along with a posterior screw provided initial stabilization of the device. Left total knee replacements were performed on six dogs using alignment and cutting jigs to prepare the bony surfaces. The dogs were killed 6 months following surgery. Extensive bone ingrowth was present in all pegs of every tibial component. Bone ingrowth was present in 12% of the pad area of one component, 22.7 to 41.6% in four components, and 81.1% in another. The void spaces in other areas were filled with fibrous tissue or in the periphery of the device with fibrocartilage. Bone ingrowth in the pad was consistent in the vicinity of the pegs and was variable in regions not adjacent to the pegs, suggesting that the pegs exerted a strong influence on the pattern of bone ingrowth into the pad.