bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructural findings after intraarticular application of hyaluronan in a canine model of arthropathy
Authors: Wenz W. , Breusch S. J. , Graf J. , Stratmann U. 
Published: February 2005

AbstractWe investigated the effect of intraarticularly applied hyaluronic acid (hyaluronan) on the cartilaginous structure of experimentally induced chondromalacia patellae in dogs. For the induction of chondromalacia, we used the Pond‐Nuki technique, which involved severance and resection of the anterior cruciate ligament, as a canine model of arthropathy in 27 foxhounds (three groups of nine animals each). In a pilot study, we evaluated the effect of resection of the anterior cruciate ligament with no therapy. Patellar specimens were retrieved at 3, 6, and 12 weeks postoperatively. Subsequently, we compared a treatment group that received intraarticular injections of hyaluronan with a placebo group that received saline solution. The groups were compared at 3, 6, and 12 weeks postoperatively. Three animals from the treatment and placebo groups received five injections of hyaluronan during one of the 4‐week intervals (weeks 3–6, 6–9, or 12–15). Specimens were retrieved 5 weeks after the last injection. In both groups, the uninvolved contralateral knee served as a control. The specimens were taken from the medial and lateral patellar poles. Histological analysis included light microscopy and transmission electron microscopy. The structural and ultrastructural changes were assessed qualitatively and were quantified with use of a modified Mankin score. Our results indicate that chondromalacia patellae may be induced with the Pond‐Nuki technique. We found a significant reduction (p < 0.01) of cartilaginous lesions in the hyaluronan group compared with the placebo group. Our results suggest that intraarticularly applied hyaluronan is effective in delaying the degenerative process of cartilage degradation. Therefore, we conclude that the use of hyaluronan may be indicated during the early stages of chondromalacia.
Effect of in vitro testing over extended periods on the low‐load mechanical behaviour of dense connective tissues
Authors: King Graham J. W. , Pillon Corrie L. , Johnson James A. 
Published: February 2005

AbstractMany biomechanical studies are performed on dense connective tissues in the laboratory over a substantial time period; however, the effect of the in vitro testing environment on the cyclic load‐relaxation behaviour of these structures is not well established. This study evaluated the effect of long duration of testing on ligament viscoelastic behaviour, using the rabbit femur‐medial collateral ligament‐tibia complex as a model. Dissected rabbit knee joints were mounted on a materials testing machine, and isolated ligament complexes were cycled at a frequency of one cycle/min to a fixed displacement of 0.7 mm for an 18‐hour period. After an initial period of exponential load relaxation, the cyclic peak loads slowly decreased over the 18‐hour period. The average decrease in the cyclic peak load between 0.5 and 18.0 hours was 0.26% (of the original peak load) per hour (r2 = 0.934), or a total of 8.6 ± 4.6% over this period (p < 0.0001). Thus, lowload testing of dense connective tissues in the laboratory over extended periods significantly alters their biomechanical behaviour, and these changes should be considered in long‐term laboratory‐based studies of dense connective tissues.
Comparison of biomechanical and biochemical properties of cartilage from human knee and ankle pairs
Authors: Treppo Steven , Koepp Holger , Quan Emerson C. , Cole Ada A. , Kuettner Klaus E. , Grodzinsky Alan J. 
Published: February 2005

AbstractCartilage was obtained from eight matched knee (tibiofemoral and femoropatellar) and ankle (talocrural) joints of five different donors (both left and right from donors 14, 22, and 38 years of age, and left only from donors 31 and 45 years of age) within 24 hours of death. All cartilage was graded as normal by the macroscopic visual Collins' scale and the histological Mankin scale. Cylindrical disks of cartilage were harvested from 10 sites within the tibiofemoral and femoropatellar joint surfaces and four sites within the talocrural joint, and uniaxial confined compression measurements were performed to quantify a spectrum of physical properties including the equilibrium modulus, hydraulic permeability, dynamic stiffness, streaming potential, electrokinetic coupling coefficient, and electrical conductivity. Matched specimens from the same 14 sites were used for complementary measurements of biochemical composition and molecular interaction, including water content, hypotonic swelling behavior, and sulfated glycosaminoglycan and collagen contents. In comparison of the top 1‐mm slices of talar cartilage with the top 1‐mm of tibiofemoral cartilage, the talar cartilage appeared denser with a higher sulfated glycosaminoglycan content, lower water content, higher equilibrium modulus and dynamic stiffness, and lower hydraulic permeability. The equilibrium modulus increased with increasing sulfated glycosaminoglycans per wet weight and decreased with increasing water content for all joint surfaces. Multiple linear regression showed that greater than 80% of the variation in the equilibrium modulus could be accounted for by variations in the biochemical parameters (water content, sulfated glycosaminoglycans/wet weight, and hydroxyproline content/wet weight) for each joint surface. Nonhomogeneous depth‐dependent changes in the physical properties and biochemical composition of full‐thickness distal femoral cartilage were consistent with previous reports. Since the compressive deformation of cartilage during cyclic loading is confined to the more superficial regions, the differences in properties of the upper regions of the talar compared with tibiofemoral or femoropatellar cartilage may be important in the etiology of osteoarthritis.
Disc degeneration and bone density in monozygotic twins discordant for insulin‐dependent diabetes mellitus
Authors: Videman T. , Battié M. C. , Gibbons L. E. , Kaprio J. , Koskenvuo M. , Kannus P. , Raininko R. , Manninen H. 
Published: February 2005

AbstractThe effects of insulin‐dependent diabetes mellitus on bone density and connective tissue degeneration have theoretical interest and practical relevance. Several experimental studies in animals have demonstrated the harmful effects of insulin deficiency on connective tissues. However, clinical studies in humans have produced somewhat contradictory results, most likely due to difficulties controlling for general degeneration and factors associated with diabetes. In nine pairs of monozygotic twins discordant for insulin‐dependent diabetes mellitus, we compared femoral and lumbar bone mineral density (assessed by dualenergy x‐ray absorptiometry) and spinal degeneration (assessed by magnetic resonance imaging). The bone densities were, on average, 0.1–0.3% lower (p = 0.87–0.96) in diabetic patients. However, after controlling for smoking, we found that the bone density in the femoral neck was 2.5% (0.025 g/cm2) lower in diabetic individuals than in their twins (p = 0.09). The five magnetic resonance imaging parameters used to evaluate discdegeneration did not differ between diabetic patients and their twins. In conclusion, our results provide no evidence that insulin‐dependent diabetes mellitus has any major effect on bone density or disc degeneration.
Radiographic determinants of the elbow rotation axis: Experimental identification and quantitative validation
Authors: Bottlang M. , O'Rourke M. R. , Madey S. M. , Steyers C. M. , Marsh J. L. , Brown T. D. 
Published: February 2005

AbstractThis study identifies new radiographic indices to approximate the location of the elbow rotational axis. With use of electromagnetic motion tracking source data, the average rotational axis of the ulnohumeral articulation was calculated in seven cadaveric specimens. Quasi‐lateral radiographs of the elbow specimens were then analyzed to identify radiographic landmarks of the elbow axis in the lateral view. The spatial relationships of these landmarks with the elbow aligned on‐axis were contrasted with their relationships in eight distinct off‐axis alignments. Elbow axis orientation in the transverse plane (internal/external rotation) was identified by the location of a dense intramedullary cortical line, appearing in the projection of the distal humerus in relation to the periosteal surface of the posterior cortex of the humerus. This intramedullary line corresponds to the posteromedial cortex of the distal humerus. Correct alignment occurred when this line laid 27.1 ± 3.7% of the anteroposterior humeral diameter anterior from the periosteal surface of the posterior cortex. Axis orientation in the coronal plane (abduction/adduction) was identified by the concentric appearance of radiographic arcs formed by the capitellum, trochlear sulcus, and medial trochlear flange. Using these radiographic indices, three orthopaedic surgeons were able to fluoroscopically align the elbow along the axis of rotation with an accuracy of 3.7 ± 1.8°. These results are immediately applicable to fluoroscopic identification of the elbow axis. This technique can be used to increase the accuracy of hinge placement during application of hinged external fixation or distraction arthroplasty.
Structural properties of the subscapularis tendon
Authors: Halder A. , Zobitz M. E. , Schultz F. , An K. N. 
Published: February 2005

AbstractThe subscapularis muscle is an important mover and stabilizer of the glenohumeral joint. The purpose of this study was to measure regional variations in the structural properties of the subscapularis tendon in two joint positions. Subscapularis tendons from cadaveric shoulders were divided into four sections superiorly to inferiorly and tested to failure at 0 or 60° of glenohumeral abduction. Arm position had a significant influence on stiffness in the inferior and superior portions (p < 0.05). The inferior region showed a higher stiffness in the hanging‐arm position (0°) than at 60° of abduction (27.4 ± 17.7 compared with 9.5 ± 5.9 N/mm). Meanwhile, stiffness of the superior portion was higher at 60° of abduction than in the hanging‐arm position (208.7 ± 60.9 compared with 147.2 ± 32.3 N/mm). In the hanging‐arm position (0°) and at 60° of abduction, the superior and midsuperior portions failed at significantly higher loads (superior: 623.2 ± 198.6 and 478.2 ± 206.6 N at 0 and 60° of abduction, respectively; midsuperior: 706.2 ± 164.6 and 598.4 ± 268.4 N, respectively) than did the inferior portion (75.1 ± 54.2 and 30.3 ± 13.0 N, respectively). Likewise, stiffness of the superior and midsuperior portions was significantly higher than that of the inferior region in both positions. Higher stiffness and ultimate load in the superior tendon region may explain the infrequent extension of rotator cuff tears into the subscapularis tendon. Conversely, the significantly lower ultimate load and stiffness in the inferior tendon region could facilitate anterior dislocation of the humeral head when this portion stabilizes the joint in a dislocated position. Therefore, repair of torn inferior portions of the subscapularis tendon should be considered in surgery for glenohumeral instability.
Equivalence of single and incremental subfailure stretches of rabbit anterior cruciate ligament
Authors: Panjabi Manohar M. , Huang Russel C. , Cholewicki Jacek 
Published: February 2005

AbstractExperimental models are often used in the laboratory to produce incomplete soft‐tissue injuries simulating those observed clinically. Single and incremental stretch protocols have been utilized. The latter has many advantages over the former. This study was designed to determine if incremental and single ligamentous stretches are biomechanically equivalent. Eleven paired fresh rabbit bone‐anterior cruciate ligamentbone preparations were used. One of each pair (single‐stretch protocol) was stretched to 88% of the average failure deformation and then stretched to failure. The other ligament (incremental‐stretch protocol) was stretched to 55, 66, 77, and 88% of the average failure deformation and then stretched to failure. All stretches were performed at 1.2 m/sec. Stress‐relaxation tests were performed before and after the 88% stretch for both stretch protocols. Relaxation curves were parameterized as forces at six time points and were also fitted to a three‐element model. Load‐deformation curves recorded during stretch to failure were characterized by eight parameters. Each incremental stretch step produced a significant increase in deformation, indicating alteration in the mechanical properties of the ligament. Both groups of ligaments, when intact, exhibited no differences in relaxation curves (p > 0.2). The 88% stretches, produced by each of the two stretch protocols, significantly altered the viscoelastic behavior of the ligaments (p < 0.002). However, after the 88% stretch, there were no differences in either viscoelastic (p > 0.1) or load‐deformation (p > 0.1) paramters of the two stretch protocols. In conclusion, the 88% subfailure stretch significantly altered the mechanical properties of ligament, and the incremental and single stretches were biomechanically equivalent.
In vivo kinematics of total knee arthroplasty: Flat compared with concave tibial joint surface
Authors: Uvehammer J. , Kärrholm J. , Brandsson S. , Herberts P. , Carlsson L. , Karlsson J. , Regnér L. 
Published: February 2005

AbstractThis study evaluated the influence of the geometric configuration of the tibial joint area on the kinematics of the knee. Twenty‐two patients with noninflammatory arthritis and minor preoperative deformity were studied. They each received an AMK total knee replacement with retention of the posterior cruciate ligament. Eleven patients without any knee abnormalities were used as controls. The patients were stratified to either the flat (terminology of the manufacturer: standard) or concave (terminology of the manufacturer: constrained) polyethylene insert (n = 11 in each group). Knee kinematics were assessed 1 year after the operation by having the patient ascend a platform corresponding to an extension of the knee from 50 to 70° of flexion. During this motion, two film‐exchangers simultaneously exposed six to 13 pairs of serial stereoradiographs. The concave geometric configuration of the tibial insert resulted paradoxically in increased anterior‐posterior translations compared with the flat insect but no significant change of rotations and translations in the other directions. Compared with normal knees, the most obvious abnormality was increased anterior‐posterior translations (p < 0.004). At 50° of flexion, the implants with the flat tibial polyethylene insert had displaced 2 times and the concave ones had displaced 2.5 times more posteriorly than the normal knees (p ⩽ 0.001). Less internal tibial rotation was also recorded in the flexed positions for both types of inserts compared with the normal knees (p < 0.02). Four knees in four patients, who reported symptoms of instability and abnormal knee function, showed significantly increased proximal displacement of the center of the tibial plateau in the flexed position. The findings suggest that current prosthetic designs and surgical technique do not restore normal knee kinematics and indicate that design improvements should rely on in vivo kinematic studies.
Plate Fixation of Prostheses after Segmental Resection for Bone Tumours
Authors: Coathup Melanie J. , Cobb Justin P. , Walker Peter S. , Blunn Gordon W. 
Published: February 2005

AbstractThis study investigated the concept of using plates to attach endoprostheses to bone after segmental resection for bone tumours in an animal model. Titanium alloy plates integrated with the prosthesis and coated with hydroxyapatite were attached to bone by screws. This type of uncemented fixation relied on the induction of periosteal bone formation into and around the plates to secure the implant to bone. Tow, three, and six‐slotted plate designs were investigated. On retrieval, each plate was securely fixed by new bone. Bone apposition on the external surface of the plates occurred through a combination of periosteal bone production, invasion of bone through slots in the plate, and bone growth over the ends of the plates. Most plates became incorporated into a remodelled cortex. Higher bone turnover rates (μm day−1) were seen in bone in the slots of the plate compared with normal cortical bone turnover (p < 0.05). Significantly higher rates of turnover were measured beneath slotted parts of the plates compared with regions below the unslotted parts (p < 0.05). The cross‐sectional area of bone surrounding the six‐plate implant design was significantly higher than that of the three‐plate (p < 0.05) and two‐plate (p < 0.05) designs. In addition, significantly more bone formed adjacent to the six‐plated implant design compared with that in the contralateral limb (p = 0.002). However, no significant difference was found when the total cortical area around the three‐plated design was compared with that of the contralateral limb (p = 0.63). In contrast, significantly less bone was measured adjacent to the two‐plate design than in the untreated limb (p = 0.001). Image analysis also demonstrated increased cortical porosity adjacent to the six‐plate design compared with the three‐plate (p = 0.004) and two‐plate (p < 0.05) designs. Finite element analysis demonstrated that the six and three‐plate designs increased the second moment of area compared with that in the left tibia (p = 0.003 and 0.066, respectively). However, the attachment of the more flexible two‐plate design did not significantly increase the second moment of area compared with that in the contralateral limb (p = 0.235). It was concluded that due to both mechanical and biological effects, the hydroxyapatite‐coated plate designs generated new bone that enhanced fixation and encouraged plate integration into the load‐bearing structure of the cortex. This method of fixation may be an alternative to the use of intramedullary cemented stems in patients requiring bone tumour implants and may be the only way to preserve the joint in difficult cases where only short segments of bone remain.
Enhanced proliferation and differentiation of human articular chondrocytes when seeded at low cell densities in alginate In Vitro
Authors: Gagne T. A. , Chappell‐Afonso K. , Johnson J. L. , McPherson J. M. , Oldham C. A. , Tubo R. A. , Vaccaro C. , Vasios G. W. 
Published: February 2005

AbstractDedifferentiated human articular chondrocytes exhibited a wide variation in their capacity to proliferate and redifferentiate in an alginate suspension culture system. The greatest extent of proliferation and redifferentiation was seen to be dependent on the formation of clonal populations of chondrocytes and correlated mversely with the initial cell seeding density. Redifferentiating chondrocytes seeded at low density (1 × 104 cells/ml alginate) compared with chondrocytes that were seeded at high density (1 × 106 cells/ml alginate) showed a nearly 3‐fold higher median increase in cell number, a 19‐fold greater level of type‐II collagen mRNA expression, a 4‐fold greater level of aggrecan mRNA expression, and a 6‐fold greater level of sulfated glycosaminoglycan deposition at 4 weeks of culture. Matrix molecules from low‐density cultures were assembled into chondrocyte‐encapsulated, spherical extracellular matrices that were readily visualized in sections from 12‐week cultures stained with antibodies against types I and II collagen and aggrecan. Ultrastructural analysis of 12‐week low‐density cultures confirmed the presence of thin collagen fibrils throughout the matrix.
Extracellular collagen regulates expression of transforming growth factor‐β1 gene
Authors: Qi Wen‐Ning , Scully Sean P. 
Published: February 2005

AbstractA complex interrelationship exists between the extracellular matrix and cytokine signaling in articular chondrocytes. We sought to determine whether the extracellular matrix serves as a regulatory component of transforming growth factor‐β1 expression. Bovine articular chondrocytes were isolated and resuspended in alginate, yielding final extracellular protein concentrations of 0 to 1.5% (wt/vol) for type‐II or type‐I collagen. Cultures were maintained for 7 days in the presence or absence of transforming growth factor‐β1‐supplemented medium (10 ng/ml). The amount of transforming growth factor‐β1 mRNA was examined with quantitative competitive reverse transcription‐polymerase chain reaction analysis. The results indicate that exogenous transforming growth factor‐β1 stimulates endogenous transforming growth factor‐β1 mRNA expression approximately 8‐fold. This effect depended on the concentration of extracellular type‐II collagen. As the concentration of extracellular type‐II collagen is increased, the expression of transforming growth factor‐β1 mRNA decreases in both basal and transforming growth factor‐β1‐stimulated cultures. Exogenous extracellular type‐I collagen also served to negatively modulate transforming growth factor‐β1 gene expression but with a different concentration profile. The results demonstrate that transforming growth factor‐β1 mRNA expression was upregulated by exogenous transforming growth factor‐β1 and was downregulated by extracellular type‐I and type‐II collagens. The profoundly different effects on transforming growth factor‐β1 expression by the two collagens are consistent with those reported for mammary epithelial cells and likely serve as a negative feedback mechanism to preserve tissue homeostasis.
Kinetics of oxidation of pantothenic acid by chloramine‐T in perchloric acid and in alkaline medium catalyzed by OsO4: A mechanistic approach
Authors: Puttaswamy  , Jagadeesh R. V. 
Published: February 2005

AbstractKinetics of oxidation of pantothenic acid (PA) by sodium N‐chloro‐p‐toluenesulfonamide or chloramine‐T (CAT) in the presence of HClO4 and NaOH (catalyzed by OsO4) has been investigated at 313 K. The stoichiometry and oxidation products are same in both media; however, their kinetic patterns were found to be different. In acid medium, the rate shows first‐order dependence on [CAT]o, fractional‐order dependence on [PA]o, and inverse fractional‐order on [H+]. In alkaline medium, the rate shows first‐order dependence each on [CAT]o and [PA]o and fractional‐order dependence on each of [OH−] and [OsO4]. Effects of added p‐toluenesulfonamide and halide ions, varying ionic strength, and dielectric constant of medium as well as solvent isotope on the rate of reaction have been investigated. Activation parameters were evaluated, and the reaction constants involved in the mechanisms have been computed. The proposed mechanisms and the derived rate laws are consistent with the observed kinetics. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 201–210, 2005
A statistical/collisional approach to rates of bimolecular reactions at low pressure
Authors: Canepa Carlo 
Published: February 2005

AbstractAn expression for the rate constant of gas‐phase bimolecular reactions at low pressure is derived in the framework of collisional theory. The key feature of the proposed model is the calculation of the energy‐dependent rate constant in terms of the collisional cross section and the probability of reaction, expressed as the ratio of the volume in phase space that leads to product over the total volume. The contribution of the internal energy of the reacting fragments is taken into account, as well as the relative translational energy. The resulting formulation is able to account for both negative and positive temperature dependences of the rate constants of neutral and charged species. The dependence of temperature of the bimolecular rate constant is given both for reactions with and without potential energy barriers. The performance of the proposed model is tested against experimental rate constant for three well‐studied reactions by fitting the parameters of the model to experimental data at various temperatures. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 233–242, 2005