bluuebunny/crossref_metadata_2025_split huggingface dataset:
Viability of ligaments after freezing: An experimental study in a rabbit model
Authors: Frank C. , Edwards P. , McDonald D. , Bodie D. , Sabiston P. 
Published: February 2005

AbstractOur purpose in this study was to assess ligament fibroblast viability after freezing by quantifying the subsequent ability of fibroblasts to synthesize collagen in vitro. Both medial collateral ligament (MCL) complexes from 40 adolescent rabbits were studied. Collagen production was determined by in vitro incubation of ligaments in 3H‐proline (a collagen precursor) and subsequent analysis of 3H‐hydroxyproline (a marker of newly synthesized collagen). Autoradiographs determined the distributions of ligament cell activity. All right MCL complexes served as fresh controls, providing a baseline of collagen production. Each left MCL was assigned to an experimental group and was either incubated fresh (10 animals); “killed” by drying, multiple freeze thawing, or cycloheximide (six animals); or slowly frozen at −70°C without cryoprotection (24 animals). Collagen production of rapidly thawed ligaments was studied by proline incubation at 1 day, 9 days, or 6 weeks after freezing and was compared with that of contralateral fresh controls. Results demonstrate that some cells in the substance of these rabbit ligaments retained the ability to synthesize collagen in vitro after being frozen for up to 6 weeks. Mean collagen production of frozen ligaments was decreased, but tests of mean and median values as well as ratios were statistically similar to fresh contralateral ligaments in all animals. This postfreezing ligament cell survival and collagen production after −70°C storage may have implications for ligament transplantation.
Pressure recording in the subacromial bursa
Authors: Sigholm Göran , Styf Jorma , Körner Lars , Herberts Peter 
Published: February 2005

AbstractThe microcapillary infusion (MCI) technique was evaluated in monitoring pressure in the subacromial bursa in 30 shoulders in healthy volunteers. The total pressure in the bursa was studied as the volunteers held their arms at rest and as they lifted their arms and held them lifted with or without a weight of 1 kg in the hands. The pressure in the bursae at rest averaged 8 mm Hg and was found stable during a 40‐min period. When the arms were lifted, the average bursa pressure increased from 8 to 39 mm Hg. As the arms were held up, the weights were put in the hands, and the average bursa pressure then further increased to 56 mm Hg. When the infusion catheters were repeatedly flushed, during a period of 5 min and with a total of 1.2 ml of saline, the average bursa pressure doubled regardless of arm position and load in the hands. The compliance of the bursae decreased from 0.09 to 0.04 ml/mm Hg when the arms were lifted and from 0.04 to 0.02 ml/mm Hg when the arms were lifted and the hands were loaded. The MCI method was found suitable for recording pressure in the subacromial bursa during exercise.
External ultrasound can generate microampere direct currents in vivo from implanted piezoelectric materials
Authors: Cochran George V. B. , Kadaba Murali P. , Palmieri Vincent R. 
Published: February 2005

AbstractUnder development is an internal fixation plate that incorporates a piezoelectric element to generate current when excited mechanically by either weight bearing or external application of ultrasound. The intent is to deliver this current to electrodes at a fracture or osteotomy site to aid in prevention or treatment of nonunion. The present study examines quantitatively the ability of external ultrasound to generate current from small piezoelectric ceramic elements implanted in tissue. An ultrasonic transducer (2.25 MHz, 10–20 V input, <10 mW/cm2 output) was employed to excite small test coupons of a piezoelectric ceramic in vitro and in vivo with various materials, including water, PVC gel, cortical bone, and living soft tissues, interposed. In all instances, it was possible to generate currents of up to 20 μA after rectification; currents up to 1 mA were achieved in some cases. The work indicates that external ultrasonic energy could effectively power small internal devices designed to stimulate bone healing, without the need for implanted batteries or percutaneous leads.
Effect of purified human interleukin‐1 on cartilage degradation
Authors: Hubbard John R. , Steinberg James J. , Bednar Michael S. , Sledge Clement B. 
Published: February 2005

AbstractThe effects of highly purified human monocyte‐derived interleukin‐1 (IL‐1) on bovine nasal cartilage breakdown were investigated. Cartilage degradation was determined by quantifying the fraction of total proteoglycan released from cartilage during 8 days of culture. The response appeared to be chondrocyte‐dependent, for IL‐1 stimulated proteoglycan (PG) release from living but not from dead (frozen‐thawed) cartilage. IL‐1 action on living cartilage was heat labile and concentration dependent, with significant effect at 5 U/ml and maximal effect at 10–20 U/ml. Kinetic studies showed significant stimulation of PG release by 3 days of incubation with 10 U/ml IL‐1. Studies in which IL‐1 was removed on day 1 or day 4 showed that the cartilage‐degrading effect of this monokine was reversible. Although IL‐1 caused little change in the Sepharose CL‐2B chromatographic profile of released PGs using an associative elution buffer, a significant shift to lower mol wt was observed under dissociative conditions. To probe the mechanism of IL‐1 action, cartilage samples were incubated with IL‐1 in the presence of the protein synthesis inhibitor, cycloheximide, or the lysosomal membrane‐stabilizing steroid, hydrocortisone. Cycloheximide at 5–10 μg/ml completely blocked IL‐1–induced breakdown. On the other hand, 3 × 10−7 M hydrocortisone had little or no effect on IL‐1 action. IL‐1 was also shown to stimulate the degradation of human articular cartilage.
Model analysis of factors influencing the prediction of muscle forces at the knee
Authors: Mikosz R. P. , Andriacchi T. P. , Andersson G. B. J. 
Published: February 2005

AbstractA three‐dimensional stochastic mathematical muscle model of the knee joint has been developed and applied to a study in which the influence of both mechanical and physiological factors were examined in relation to the prediction of muscular forces about the joint. The model includes a representation of the proximal portion of the tibia and distal portion of the femur along with a mathematical expression of the patellar mechanism and 13 muscles crossing the knee joint. The model accounts for the rolling and gliding movement of the tibial‐femoral articulation. The computational technique involves equilibrating three components of external moments at the knee joint to the internal moments generated by muscular forces and soft tissue. The variables contained in the moment equilibrium equation are randomly chosen based on the choice of the tibial‐femoral contact point. The randomness of the variables, reflected in the final solution, defines a stochastic process in the context of the present model. Studies with the model indicated that a very important mechanical aspect of the model was the capability to simulate the moving contact point between the tibia and femur. The moving contact point increased the mechanical advantage of the quadriceps muscles by 50%, which corresponded to in vivo EMG measurements. Muscle force predictions during normal gait have shown the capability of the model to determine the presence of synergistic and antagonistic muscle action.
Energy‐speed relationship of walking: Standard tables
Authors: Waters Robert L. , Lunsford Brenda Rae , Perry Jacquelin , Byrd Richard 
Published: February 2005

AbstractThe energy expenditure of level walking was measured in 260 normal male and female subjects walking around a 60.5m‐circular outdoor track. Subjects were divided into four age groups (children, 6–12 years; teens; young adults, 20–59 years; and senior adults, 60–80 years). Oxygen consumption was measured with a modified Douglas Bag technique during the fourth and fifth minutes of each trial. Standard tables according to age and sex were derived for the average energy expenditure (rate of oxygen uptake, energy cost per meter, and heart rate) and for the gait characteristics (speed, cadence, stride length) at the subjects' customary slow, normal, and fast walking speeds. Statistical analysis was performed to determine the energy–speed relationship for the different age groups to derive normative tables for the rate of oxygen uptake throughout the range of customary walking velocities.
Viscous isoamyl 2‐cyanoacrylate as an osseous adhesive in the repair of osteochondral osteotomies in rabbits
Authors: Harper Marion C. 
Published: February 2005

AbstractAn in vivo study of viscous isoamyl 2‐cyanoacrylate used in limited amounts as an osseous adhesive was performed to evaluate the ability of the monomer to maintain the reduction of an unstable intra‐articular osteochondral osteotomy as well as to allow for healing around the sites of adhesive placement. A histologic evaluation of any inflammatory reaction involving adjacent bone, cartilage, or synovium was also performed. Osteochondral fragments were created in 48 rabbit knees. In 24 knees, reduction of the fragment was secured with one small drop of adhesive at either end of the osteotomy surface. In 24 control knees, no adhesive was used. Ninety‐six percent of the osteotomies in the adhesive treated group healed versus 50% of the control group. This difference is statistically significant (p < 0.05). Osseous and cartilaginous healing was noted to proceed in an apparently unimpaired fashion around the sites of adhesive placement, and no inflammatory reaction involving adjacent viable tissue was evident.
Pulsed ultrasound doppler velocimetry in the assessment of microvascular hemodynamics
Authors: Blair William F. , Brown Thomas D. , Greene E. R. 
Published: February 2005

AbstractPulsed ultrasonic Doppler velocimetry (20 MHz) (PUDVM) has evolved considerably in the last 10 years. Engineering development has resulted in a computer‐controlled vessel‐scanning instrument whose backscattered frequency shift spectra are analyzed using fast Fourier transforms (FFT). Benchtop and theoretic studies indicate accurate (error <5%) velocity and volumetric flow rate measurements in vessels with a lumen diameter as small as 1.2 mm. Clinical application of the PUDVM has provided transcutaneous measurements of blood flow variables in normal human digital arteries. Experimental application to arteries 1.0–1.5 mm has provided information on the hemodynamic effects of topical vasodilators, standard microarteriorrhaphy, variations in microvascular technique, interpositional grafts, and early wound repair. With improving computer capabilities and technical modifications, the PUDVM will be an increasingly important tool in clinical and experimental microsurgery.
The mineral and mechanical properties of bone in chronic experimental diabetes
Authors: Einhorn Thomas A. , Boskey Adele L. , Gundberg Caren M. , Vigorita Vincent J. , Devlin Vincent J. , Beyer Monica M. 
Published: February 2005

AbstractThe long‐term effects of experimentally induced diabetes on bone were studied in eight male Lewis rats, intravenously (i.v.) injected with 65 mg/kg of streptozocin (STZ) and maintained for 12 months. Eight untreated age‐matched rats served as controls. In the STZ‐treated rats, experimentally induced diabetes was documented by the presence of hyperglycemia at 24 h and at 3 and 12 months. Significantly less weight was gained and less growth occurred in the STZ‐treated rats despite careful attention to feeding and hydration. Mineral alterations were detected in the bones of the animals with experimental diabetes. Decreased hydroxyapatite crystal perfection, decreased Ca/P of the ash, and decreased ash content in the tibial metaphyses with increased ash content in the tibial diaphyses, was noted relative to controls. Bone osteocalcin content was increased in the metaphyses of the STZ‐treated rats. While absolute measures of stiffness, torsional strength and energy absorption were decreased in the bones of the STZ‐treated animals, when torsional strength and stiffness were normalized for differences in both growth and geometry, the normalized stiffness values for the diabetic bones were increased. The results suggest that in experimental diabetes certain aspects of bone mineralization are adversely affected and lead to reduced strength‐related properties. However, a compensatory increase in stiffness occurs. The reason for this increase, although not known, may be related to changes in bone crystal structure.
Changes in bioelectric potentials on bone associated with direct current stimulation of osteogenesis
Authors: Rubinacci Alessandro , Black Jonathan , Brighton Carl T. , Friedenberg Zachary B. 
Published: February 2005

AbstractThis study was designed to determine whether changes occur in the bioelectric potentials on bone during and after bone stimulation with a 20‐μA direct current (DC) and whether the variations in bioelectric potentials are related to the variations in bone formation. The bioelectric potentials were recorded at different times on the rabbit distal tibial surface, during (current‐on state) and after (current‐off state) DC stimulation with a cathode implanted within the medullary canal. The new bone formed at the end of the experiment was quantitated and related to the bioelectric potentials recorded at current‐on and current‐off states, respectively. Direct current stimulation resulted in electronegative potential spike centered on the cathode tip while current was applied. After electrical stimulation was turned off, the residual potentials at the end of the experiment did not significantly differ from the initial values. Conversely, the time sequence of the changes was significantly different from the control to the experimental group. The variations in the induced potentials at current‐on state were significantly related to the variations in bone formation. This study suggests the existence of a relationship among bioelectric potentials, DC stimulation, and osteogenesis.
Strength reductions from metastatic cortical defects in long bones
Authors: McBroom R. J. , Cheal E. J. , Hayes W. C. 
Published: February 2005

AbstractThe purpose of this investigation was to measure the reduction in bone strength resulting from drill holes in diaphyseal bone and to compare this with finite element and theoretical predictions for stresses in a tubular structure. Fifty‐two pairs of canine femora were tested to failure in four‐point bending. One bone of each pair was used as the control; the other femora had holes of variable size drilled in the lateral cortex. At a ratio of drill hole diameter to bone diameter of 0.2, the bone retained only 62% of its expected strength. A linear regression between the area fraction (the ratio of the cross‐sectional area of the drilled specimen to the control specimen) and the percentage of expected strength yielded a strong positive correlation (R2 = 0.79). The average cross sectional properties were used as the basis for linear orthotropic and nonlinear elastic‐plastic finite element models of idealized geometry. The linear models proved insuifficient for prediction of failure loads. The nonlinear models, which accounted for both material plasticity and the stress concentration effects of the defect, yielded good correspondence with the experimental data. While the influence of irregular borders and adaptive remodeling of the bone adjacent to the defect requires further investigation, our results suggest the possibility of prediction of fracture risk based on geometric properties of metastatic lesions. Prophylactic fixation remains a matter of clinical judgement based on the functional demands and expected strength of the affected bones.
Stimulation of matrix formation in rabbit chondrocyte cultures by ascorbate. 1. Effect of ascorbate analogs and β‐aminopropionitrile
Authors: Wright George C. , Wei Xiqin , McDevitt Cahir A. , Lane Bernard P. , Sokoloff Leon 
Published: February 2005

AbstractThe most consistent effects of 0.2 mM L‐ascorbate on monolayer cultures of rabbit articular chondrocytes were a diversion of incorporated radiosulfate into a pericellular matrix and enhancement of cell proliferation. Only with certain batches of fetal bovine serum (FBS) was there a cell‐for‐cell increase of proteoglycan synthesis. These actions increased as the cell inoculum rose from 0.5 to 2 × 105 cells/T25 flask. Maximal effects of ascorbate and D‐isoascorbate were found over a range of 0.05–0.02 mM. L‐Dehydroascorbic acid was less effective than either, and no stimulatory action was exerted by L‐cysteine, glutathione, dithiothreitol, methylene blue, or phenazine methosulfate. Ascorbate increased the hypro:pro ratio of newly synthesized proteins. β‐Aminopropionitrile (1 mM) reduced the proportion of [3H]hydroxyproline and [35S]O4‐proteoglycans in the ascorbate‐supplemented matrix 31 and 7%, respectively. In corresponding electronmicrographs, the number of pericellular filaments was reduced. We conclude: (a) Ascorbate has a general anabolic effect on chondrocytes in culture and enhances matrix assembly through mechanisms other than its redox function; (b) deposition of proteoglycans in the matrix is not simply the result of mechanical entrapment by allysine‐ or hydroxyallysine‐derived cross‐linking of collagen; and (c) contradictory reports on the subject result from variations in the serum employed, inoculum density, and concentration of ascorbate.
Resultant forces and angles of twist about the wrist after the ecrl to ecu tendon transfer
Authors: Berger Richard A. , Blair William F. , Andrews James G. 
Published: February 2005

AbstractThis paper describes an experimental investigation to determine the biomechanical efficacy of the extensor carpi radialis longus (ECRL) to extensor carpi ulnaris (ECU) tendon transfer procedure used in rheumatoid hand reconstruction. Six normal cadaver specimens were tested in an apparatus that measured (a) the forces acting on the hand to restrain it in seven characteristic wrist configurations, and (b) the amount of hand pronation/supination that occurred as a result of loads applied to the tendons of the six major wrist muscles. Each specimen was tested with the ECRL tendon intact, surgically released, and transferred to the insertion point of ECU. In the intact and transferred states, the ECRL tendon was loaded sequentially while the remaining five wrist tendons were subjected to equal constant loads. In all three experimental ECRL test states, forces were also applied to all intact wrist tendons in a manner designed to represent physiologic load sharing. When the ECRL tendon was loaded sequentially, the transfer resulted in the predictable increase in the radially directed restraining force and the predictable supination of the hand relative to the forearm. When all intact tendons were loaded physiologically, the transfer also resulted in an increase in the radially directed restraining force. Significant differences between test states occurred generally only between the intact and release states of the ECRL tendon and not between release and transferred states. The results confirm that the ECRL‐to‐ECU tendon transfer procedure leads to forces and displacements that tend to correct the undesired deformities commonly associated with advanced rheumatoid wrist disease; however, the similarity of results in release and transferred states indicates that the effectiveness of the procedure involves the loss of normal ECRL function rather than reinsertion into the ECU per se.
An apparatus to measure flexor tendon excursion and angular motion of the distal interphalangeal joint in a rabbit model
Authors: Younger Edward W. , Sharkey Neil A. , Szabo Robert M. 
Published: February 2005

AbstractInvestigators evaluating flexor tendon adhesions have utilized visual, histological, and gross mechanical methods in reporting their results. We have developed a device to measure tendon excursion and distal interphalangeal joint motion for a small animal model. The device was tested for accuracy and reproducibility using the rabbit hindfoot. There was no statistical difference between the right and the left in 30 paris of feet. This device provides an accurate method to quantify tendon excursion and relative adhesion formation in a rabbit model without destroying the specimen.
Stimulation of matrix formation in rabbit chondrocyte cultures by ascorbate. 2. Characterization of proteoglycans
Authors: McDevitt Cahir A. , Lipman Jack M. , Ruemer Robert J. , Sokoloff Leon 
Published: February 2005

AbstractThe effect of ascorbate on the proteoglycans synthesized by rabbit articular chondrocytes was studied in first‐ and third‐passage cultures for 12 and 26 days total duration, respectively. L‐Ascorbate (0.2 mM) was added daily to half of the flasks after attachment of the cells. The cultures were labeled with Na2[35S]O4 or [14C]‐glucosamine and [3H]‐proline. Proteoglycans were isolated from the media and pericellular matrices by dissociative extraction and associative density gradient centrifugation. There was a large decline in the amount of proteoglycan synthesized between early and late cultures. Ascorbate increased the DNA content, amount of radiosulfate incorporated into glycosaminoglycans per microgram of DNA, and the proportion of labeled proteoglycan in the percellular fraction of both short‐ and long‐term cultures. The proteoglycans of the media and matrices of all cultures, with and without ascorbate, eluted as aggregates under associative column chromatographic conditons. The proteoglycans of 26‐day cultures exhibited a higher degree of polydispersity in size than those of the short‐term culture and contained small amount of keratan (2–5%) and dermatan sulfate (4–8%) as assessed by keratanase and chondroitinase digestions, respectively. The effect of ascorbate, therefore, was to increase the amount of proteoglycan formed and to direct it into matrix deposition rather than to alter its quality.
The synovial production of collagenase and chondrocyte activating factors in response to cobalt
Authors: Ferguson Gary M. , Watanabe Shoji , Georgescu Helga I. , Evans Christopher H. 
Published: February 2005

AbstractAddition of CoCl2 solutions to the culture media of confluent monolayers of lapine or human synoviocytes stimulated their production of the neutral proteinases collagenase, gelatinase, and caseinase. With lapine cells, maximum stimulation occurred at 10−7 M CoCl2, while human cells required 10−4–10−5 M CoCl2 to achieve a maximum stimulation. Production of prostaglandin E2 by lapine cells was enhanced some 30–40% by concentrations of CoCl2 that maximally stimulated synthesis of the neutral proteinases, whereas all concentrations of CoCl2 slightly depressed the productio of prostaglandin E2 by human celis. Lapine synovial cells that had been stimulated by CoCl2 also produced a substance, or substances, that provoked the synthesis of collagenase, gelatinase, caseinase, and prostaglandin E2 by monolayers of articular chondrocytes. Chondrocytes themselves, however, resisted activation by CoCl2. These findings may be relevant to the aseptic loosening of joint prostheses.