bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anatomy of the human patellofemoral joint articular cartilage: Surface curvature analysis
Authors: Kwak S. Daniel , Colman William W. , Ateshian Gerard A. , Grelsamer Ronald P. , Henry Jack H. , Mow Van C. 
Published: February 2005

AbstractArticular cartilage surfaces of 49 human patellae and 24 distal femora were characterized by identifying distinctive features with surface curvature analysis. Paired specimens from the same donor generally exhibited natural symmetry, so only results from nonpaired specimens were considered (39 patellae and 19 femora). In 23 of 39 patellae, proximal median and lateral transverse ridges extended to form an oblique ridge resembling a skewed lambda (λ). Most of the unpaired patellae (37 of 39) exhibited only a single lateral transverse ridge, and most (32 of 39) had an odd facet. All but one patella exhibited a concave depression in the lateral and medial facets and a sellar area in the proximal region. All distal femoral surfaces exhibited a sellar trochlea. The concavity of the trochlea was greatest in the posterioraspect, near the intercondylar notch.
Growth hormone secretagogue increases muscle strength during remobilization after canine hindlimb immobilization
Authors: Lieber Richard L. , Jacks Thomas M. , Mohler Randall L. , Schleim Klaus , Haven Michelle , Cuizon Denise , Gershuni David H. , Lopez Michael A. , Hora Donald , Nargund Ravi , Feeney William , Hickey Gerard J. 
Published: February 2005

AbstractTwenty‐two beagles were divided into two equal groups, and the right hindlimb of each animal was immobilized at 105° of knee flexion by external fixation. After 10 weeks of fixation, the device was removed, allowing free mobility for the following 5 weeks. Each day throughout the 15 weeks, one group received a growth hormone secretagogue (treatment) at a dose of 5 mg/kg, and the other received a lactose placebo (control). At weeks 0, 10, and 15, strength as indicated by maximum isometric extension torque was measuredin the right hindlimb, biopsies of the vastus lateralis muscle were taken, and the dogs were weighed. Weekly blood samples were analyzed for insulin‐like growth factor‐I, blood urea nitrogen, and creatine phosphokaase. Between weeks 0 and 10, tetanic torque declined by about 60% (p < 0.001) in both groups, with no significant difference between the groups (p > 0.7). Between weeks 10 and 15, tetanic torque in the treated group increased by 0.81 Nm; this was significantly greater than the increase of 0.25 Nm in the placebo group (p < 0.05). The diameters of slow (type‐1) and fast (type‐2) fibers measured from the vastus lateralis muscle followed the same trend. At all time points, fiber diameter correlated strongly with torque; this argues against nonmuscular causes such as nerve injury for strength loss. The mean levels of insulin‐like growth factor‐1 increased 100% by week 4 in the treated group and remained elevated by about 60% throughout the experiment. Levels of insulin‐like growth factor‐1 in the placebo group decreased 30% within week 1 and remained depressed throughout the experiment. Our interpretation of these data suggests that the growth hormone secretagogue elevated levels of serum insulin‐like growth factor‐1, which in turn increased the size and strength of the quadriceos muscle during remobilization. These data may ultimately have therapeutic application to humans during rehabilitation after prolonged inactivity.
Prosthetic metals impair murine immune response and cytokine release in vivo and in vitro
Authors: Wang James Y. , Wicklund Barb H. , Gustilo Ramon B. , Tsukayama Dean T. 
Published: February 2005

AbstractThis study was designed to investigate whether prosthetic metals adversely affect immune responses and the release of immunoregulatory cytokines in vivo and in vitro. Titanium and cobalt‐chromium alloy were injected into the peritoneal cavity of female mice. At 5, 8, and 12 weeks after the injection, the levels of cobalt and chromium in the blood were significantly increased compared with the levels in control mice; the level of titanium was not significantly changed until 12 weeks. The release of interleukin‐2 was significantly inhibited by cobalt‐chromium particles after 3 weeks; titanium particles did not have the same effect until 8 and 12 weeks. The release of interleukin‐γ was significantly inhibited by cobalt‐chromium particles after 3 weeks but was not significantly inhibited by titanium particles until 12 weeks. The release of interferon‐y was significantly inhibited by cobalt‐chromium particles only at 12 weeks and was not inhibited by titanium particles. The proliferation of T cells was significantly inhibited by cobalt‐chromium particles at 3 weeks and by titanium particles at 8 and 12 weeks, and the proliferation of B cells was significantly inhibited by cobalt‐chromium particles after 3 weeks but was not inhibited by titanium particles. The production of immunoglobulin by lipopolysaccharide‐stimulated B cells was also significantly reduced by cobalt‐chromium particles after 3 weeks and by titanium particles at 8 and 12 weeks. The cytokine release by lymphocytes, proliferation of T and B cells, and immunoglobulin production by B cells were also significantly inhibited by titanium and cobalt‐chromium particles, as well as by titanium, cobalt, and chromium ions in vitro, whereas these metals are not cytotoxic to murine lymphocytes in vitro. The data indicate that the metal‐induced immunosuppression may be another important factor in the development of implant‐associated infection in patients with a prosthesis.
Biochemical and molecular homogeneity in the patellar tendon of the immature pig
Authors: Yin C. , Wayne J. S. , Jiranek W. A. , Zuelzer W. A. 
Published: February 2005

AbstractPatellar tendon is widely used for reconstruction of the anterior cruciate ligament. However, few studies have investigated the tendon's homogeneity, a characteristic often assumed of it in experiments. In this study, the assumption that the patellar tendon is homogeneous was tested by dividing the central half of the tendon into six sections along its length and width and comparing commonly measured biochemical parameters and patterns of gene expression among these sections. No significant differences were found between the sections for any of the studied parameters: water content (p > 0.5). DNA content (p > 0.9), total collagen content (p > 0.8), amount of type‐I collagen (p > 0.7) or type‐III collagen (p > 0.7), or expression of mRNA (p > 0.9). For all parameters, the minimum power value for statistical analyses was greater than 0.80. It was concluded that the central half of the tendon is homogeneous in terms of all of the measured parameters. The results provide important information for the many experiments that sample part of the patellar tendon to infer the characteristics of the whole tendon, e.g., biopsy studies.
Chondrocyte transplantation to articular cartilage explants in vitro
Authors: Chen Albert C. , Nagrampa Jennifer P. , Schinagl Robert M. , Lottman Lisa M. , Sah Robert L. 
Published: February 2005

AbstractThe transplantation of chondrocytes has shown promise for augmenting the repair of defects in articular cartilage. This in vitro study examined the efficiency of the transplantation of bovine chondrocytes onto articular cartilage disks and the ability of the transplanted chondrocytes to subsequently synthesize and deposit proteoglycan. The radiolabeling of chondrocyte cultures with [3H]thymidine, followed by 4 days of chase incubation, resulted in the incorporation of 98% of the radiolabel into DNA (as assessed by susceptibility to DNase). At the end of the culture period, the [3H]DNA was stable, with a half‐life of radioactivity loss into the medium of 73 days. With use of radiolabeled chondrocytes for quantitation, the efficiency of transplantation onto a cartilage substrate was 93 ± 4% for seeding densities of as much as 650,000 cells per cm2 and a seeding duration of 1 hour. These findings were confirmed both by tracking cells stained with 5‐chlormethylfluorescein diacetate and by quantitating DNA. During the 16 hours after seeding onto a cartilage substrate (in which the endogenous cells had been lysed by lyophilization), the transplanted cells synthesized sulfated proteoglycan in direct proportion to the number of cells seeded. Most (83%) of the newly synthesized proteoglycan was released into the medium rather than retained within the layer of transplanted cells and the recipient cartilage substrate. Comparative studies with lyophilized‐rehydrated or live cartilage as the recipient substrate indicated a similar efficiency of chondrocyte seeding and proteoglycan synthesis by the seeded chondrocytes. The transplanted cells retained the chondrocyte phenotype, as judged by a high proportion of the [35S]macromolecules being in the form of aggrecan that was capable of aggregating with hyaluronan and link protein, as well as by immunostaining within and around the transplanted cells for type‐II, but not type‐1, collagen. These results indicate that the number of chondrocytes transplanted onto a cut cartilage surface greatly affects the level of matrix synthesis; this in turn may affect repair.
Chondrogenic phenotype of perichondrium‐derived chondroprogenitor cells is influenced by transforming growth factor‐beta 1
Authors: Dounchis J. S. , Goomer R. S. , Harwood F. L. , Khatod M. , Coutts R. D. , Amiel D. 
Published: February 2005

AbstractOur laboratory has developed a method for the repair of osteochondral defects by implanting cultured perichondrial cells attached to a biodegradable polylactic acid scaffold. The success of this approach depends in part on the proliferative characteristics and the phenotype of the implanted cells. Transforming growth factor‐beta 1 has been reported to influence these parameters in several mesenchymal‐derived tissues in vitro and in vivo. The chondrocytic phenotype is marked by an enhanced expression of the collagen type‐II gene. In this study, cultures grown from explants of rabbit rib perichondrium were exposed to exogenously added transforming growth factor‐beta 1 at concentrations of 0.1–10 ng/ml of media. Cell proliferation and collagen gene expression were measured. The expression of types I and II collagen genes was analyzed by Northern blot and reverse transcriptase‐polymerase chain reaction. The exogenous addition of transforming growth factor‐beta 1 at a concentration of 0.1–10 ng/ml resulted in tritiated thymidine uptake by perichondrial cells, with optimum proliferative effects at 0.1 ng/ml. Transforming growth factor‐beta 1 added at concentrations of 0.1 and 0.5 ng/ml significantly upregulated the expression of type‐II collagen mRNAs. The results suggest that, when the chondrocytic phenotype is defined by markedly enhanced type‐II collagen gene expression, the chondrocytic phenotype of explant cultures of perichondrium‐derived cells is enhanced by the Kogenous; addition of transforming growth factor‐beta 1.
Repeatability of patellar cartilage thickness patterns in the living, using a fat‐suppressed magnetic resonance imaging sequence with short acquisition time and three‐dimensinal data processing
Authors: Tieschky Marcus , Faber Sonja , Haubner Michael , Kolem Heiner , Schulte Erik , Englmeier Karl‐Hans , Reiser Maximilian , Eckstein Felix 
Published: February 2005

AbstractA fast, reproducible, and noninvasive method is required for quantifying cartilage thickness clinically and for studying the deformation of articular cartilage during and after mechanical loading in vivo. The objective of the current investigation was to test the repeatability of regional distribution patterns of patellar cartilage thickness in the living on the basis of a fat‐suppressed magnetic resonance imaging sequence with a short acquisition time and three‐dimensional digital data processing. The knees of eight healthy volunteers were transversally imaged with a fat‐suppressed FLASH‐3D (fast low angle shot) sequence (acquisition time: 4 minutes and 10 seconds). In each case, the joint was newly positioned before each of the six replicate measurements was taken. The patellar cartilage was reconstructed three‐dimensionally, and the distribution of cartilage thickness was determined with a three‐dimensional minimal‐distance algorithm. Whereas the cartilage volume ranged from 3,198 to 7,149 mm3, the mean coefficient of variation for the 6‐fold volume measurement was 1.35%. On average, 75.1% (±4.1%) of all test pixels could be attributed to the same cartilage thickness interval (0.5 mm) by image analysis; 14.8% (±2.4%) deviated by one interval; 6.6% (±1.5%), by two intervals; and 3.5% (±1.8%), by more than two intervals. We conclude that, on the basis of a magnetic resonance imaging sequence with an acquisition time of less than 5 minutes, the quantitative distribution of cartilage thickness can be determined with high precision in vivo.
Residual stresses in ultra‐high molecular weight polyethylene loaded cyclically by a rigid moving indenter in nonconforming geometries
Authors: Estupiñán Jaime A. , Bartel Donald L. , Wright Timothy M. 
Published: February 2005

AbstractThe characterization of stress and deformation fields that incorporate moving cyclic loads and nonlinear material response in ultra‐high molecular weight polyethylene components for total knee replacements is required to quantify mechanisms of surface damage. A simulation of stresses in polyethylene components for total knee replacement subjected to cyclic moving loads was performed with use of nonlinear finite element analysis. Convergence to a steady‐state cycle of stress and deformation was observed within five cycles of loading. Differential plastic deformation under the surface of the polyethylene led to horizontal residual stresses that were tensile at the surface and compressive in the subsurface. The magnitudes of the residual J stresses indicate their importance in surface failure mechanisms. Horizontal residual tensile stresses at the surface are consistent with the initiation and propagation of surface cracks that could cause pitting in polyethylene. Horizontal residual compressive stresses under the surface could cause such cracks to arrest or turn and thus limit damage to a region just beneath the surface. The results emphasize the importance of incorporating nonlinear effects to simulate long‐term stress fields associated with surface damage in polyethylene.
Kinematics of the glenohumeral joint with bankart lesion and repair
Authors: Novotny John E. , Nichols Claude E. , Beynnon Bruce D. 
Published: February 2005

AbstractA Bankart repair is performed to reduce abnormal translations of the humeral head on the glenoid due to a Bankart lesion, a separation of the capsulolabral complex from the glenoid rim. However, this is often accompanied by a loss of rotational range of motion that may lead to decreased function and osteoarthritis. This loss of rotation, coupled to the goal of reducing humeral translations, may be a result of the amount of imbrication of the capsule during repair. To determine the effects of capsular imbrication, we investigated how two Bankart repairs (2.5 and 5.0 mm of capsular imbrication) and a Bankart lesion altered the translations and rotations of the human glenohumeral joint in vitro. Coupled moments were applied to the unconstrained humerus in abduction‐adduction, in flexion‐extension, and to simulate the cocked phase of throwing. Motion was measured with an electromagnetic system. There were no differences in the kinematics betweenthe intact specimens and those with a Bankart lesion or between normal specimens and the first (2.5 mm) Bankart repair. The first repair significantly reduced external rotation for the cocked phase of throwing compared with the Bankart lesion: from 46.8 ± 23.6° to 32.4 ± 14.2° (±SD). The second (5.0 mm) Bankart repair produced significantly different posterior translation (‐4.7 ± 3.9 mm) of the humeral head relative to the glenoid compared with normal (5.1 ± 4.7 mm anterior) and the first repair (6.1 ± 8.3 mm anterior), as the humerus moved from full flexion to full extension. Differences were also found for all rotations in the cocked phase of throwing. For the second repair, the humerus extended 24.3° and externally rotated 18.6° less than normal and was abducted 15.4° more. These results indicate that both Bankart repairs do little to affect humeral translations with unconstrained moment loading but that rotations are affected during the cocked phase of throwing, with significant losses of external and extension rotations.
Osteoblast cytoskeletal modulation in response to mechanical strain in vitro
Authors: Meazzini M. C. , Toma C. D. , Schaffef J. L. , Gray M. L. , Gerstenfeld L. C. 
Published: February 2005

AbstractThe structural integrity of microfilaments has been shown to be necessary for the signal transduction of mechanical stimuli within osteoblasts. Qualitative and quantitative changes within the cytoskeleton of osteoblasts may therefore be crucial components of the signal transduction processes of these cells in response to mechanical stimulation. Avian osteoblasts were strained with a device that deforms a flexible, cell‐laden membrane at a defined frequency and intensity in a uniform biaxial manner. We examined the effects of mechanical strain on the accumulation of protein and the expression of the major cytoskeletal elements and specific integrin‐binding (arginine‐glycine‐aspartic acid) proteins of these cells. Mechanical strain increased the level of total extracellular matrix‐accumulated fibronectin by approximately 150% and decreased that of osteopontin by approximately 60% but had no quantifiable effect on the accumulation of β1 integrin subunit or collagen type I. An examination of the major elements of the cytoskeleton demonstrated that neither the level of actin nor that of the intermediate filament protein vimentin changed; however, the amount of tubulin decreased by approximately 75% and the amount of vinculin, a major protein of focal adhesion complexes, increased by approximately 250%. An analysis of protein synthesis by two‐dimensional gel electrophoresis of [35S]methionine‐labeled cytoskeletal proteins demonstrated that the changes in the accumulation of vinculin and tubulin resulted from their altered synthesis. Messenger RNA analysis confirmed that the changes in accumulation and protein synthesis observed for vinculin, fibronectin, and osteopontin were controlled at a pretranslational level. Immunofluorescent microscopy demonstrated that mechanical strain led to increased formation and thickening of actin stress fibers, with a commensurate dissociation in microtubules and a clear increase in levels of vinculin at the peripheral edges of the cells. In conclusion, the elevated rate of synthesis and the increased accumulation of vinculin and fibronectin, as well as the increase in the number and size of stress fibers and focal adhesion complexes, suggest that mechanical strain leads to a coordinated change both in the cytoskeleton and in extracellular matrix proteins that will facilitate tighter adhesion of an osteoblast to its extracellular matrix.
Expression of a stable articular cartilage phenotype without evidence of hypertrophy by adult human articular chondrocytes in vitro
Authors: Binette François , McQuaid David P. , Haudenschild Dominik R. , Yaeger Peter C. , McPherson John M. , Tubo Ross 
Published: February 2005

AbstractChondrocytes that were isolated from adult human articular cartilage changed phenotype during monolayer tissue culture, as characterized by a fibroblastic morphology and cellular proliferation. Increased proliferation was accompanied by downregulation of the cartilage‐specific extracellular matrix proteoglycan, aggrecan, by cessation of type‐II collagen expression, and by upregulation of type‐I collagen and versican. This phenomenon observed in monolayer was reversible after the transfer of cells to a suspension culture system. The transfer of chondrocytes to suspension culture in alginate beads resulted in the rapid upregulation of aggrecan and type‐II collagen and the downregulation of expression of versican and type‐I collagen. Type‐X collagen and osteopontin, markers of chondrocyte hypertrophy and commitment to endochondral ossification, were not expressed by adult articular chondrocytes cultured in alginate, even after 5 months. In contrast, type‐X collagen was expressed within 2 weeks in a population of cells derived from a fetal growth plate. The inability of adult articular chondrocytes to express markers of chondrocyte hypertrophy has underscored the fundamental distinction between the differentiation pathways that lead to articular cartilage or to bone. Adult articular chondrocytes expressed only hyaline articular cartilage markers without evidence of hypertrophy.
Exposure of cartilage to a fibronectin fragment amplifies catabolic processes while also enhancing anabolic processes to limit damage
Authors: Homandberg Gene A. , Wen Catherine 
Published: February 2005

AbstractThe addition of fibronectin fragments to cultured cartilage causes an initial suppression of proteoglycan synthesis, induction of matrix metalloproteinases, and resultant decrease in proteoglycan content by about 50% during the first few days in culture. Because the proteoglycan loss appears to be limited, we investigated whether the fibronectin fragments induce anabolic responses that might counter the damage. The effects of various lengths of exposure of cultured cartilage to the fibronectin fragment on proteoglycan content, proteoglycan synthesis rates, stromelysin‐1 release, and tumor necrosis factor‐α, interleukin‐1α, and interleukin‐6 release were investigated. The results showed that about 7 days of exposure of cultured cartilage to the fibronectin fragment was required for maximal cytokine release, proteoglycan depletion, and stromelysin‐1 release. However, nearly maximal suppression of proteoglycan synthesis occurred within 1 day of the addition of the fibronectin fragment and, after its removal, the rates increased to supernormal levels. Decreasing exposure to 3 days caused only a small decrease in cartilage proteoglycan content, although stromelysin‐1 release still occurred. Decreasing exposure to 1 day caused an immediate increase in proteoglycan synthesis and an increase to supernormal proteoglycan contents. The effect of first treating cartilage with the fibronectin fragment for various periods and then allowing a recovery was to make the cartilage more resistant to secondary exposures. This study shows that cartilage damage can be caused by short exposures to the fibronectin fragment and that exposures either optimal or suboptimal for damage additionally amplify anabolic processes to make the cartilage resistant to further damage and, thus, condition it against pending amplification of damage.