bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of chemotactic migration and growth kinetics of canine knee ligament fibroblasts
Authors: Hannafin Jo A. , Attia Erik T. , Warren Russell F. , Bhargava Madhu M. 
Published: February 2005

AbstractMigration and proliferation of ligament fibroblasts are essential for the healing of ligament injuries. This study was designed to evaluate the migration of intraarticular (anterior and posterior cruciate) and extraarticular (medial and lateral collateral) ligament fibroblasts in response to cytokines and to determine the effect of cell passage on cell proliferation. Recombinant human platelet‐derived growth factor, hepatocyte growth factor/scatter factor, and bone morphogenic protein‐2 stimulated the migration of all ligament cells in a dose‐dependent manner, with optimal migration at 10 ng/ml. Recombinant human epithelial growth factor preferentially stimulated the migration of intraarticular ligament fibroblasts, whereas recombinant human interleukin‐1 was more effective with extraarticular ligament fibroblasts. Recombinant human insulin‐like growth factor‐1, insulin‐like growth factor‐2, transforming growth factor‐beta, and fibroblast growth factor had no significant effect on the migration of ligament‐derived fibroblasts. These data suggest that specific cytokines stimulate the migration of knee ligament fibroblasts and provide a rationale for possible therapeutic approacnes to optimize ligament healing. Fibroblasts derived from the anterior cruciate ligament have been shown to proliferate at a slower rate than those derived from the medial collateral ligament. We have extended these observations and have demonstrated that fibroblasts from both the posterior and anterior cruciate ligaments proliferate at a slower rate than lateral and medial collateral ligament‐derived fibroblasts. The differences between the growth rates of intraarticular and extraarticular fibroblasts become insignificant with serial passaging of the cells.
Estrogen level alters the failure load of the rabbit anterior cruciate ligament
Authors: Slauterbeck James , Clevenger Chris , Lundberg William , Burchfield Daniel M. 
Published: February 2005

AbstractWe hypothesized that increasing the level of circulating serum estrogen would decrease the load at failure for the rabbit anterior cruciate ligament. We developed an animal model in which hormonal manipulations could be correlated with load at failure for the anterior cruciate ligament. Sixteen New Zealand White ovariectomized rabbits were matched and divided into two groups. The eight rabbits that were not treated with the estrogen supplement (Group O) and the eight that were treated with the supplement (Group E) were housed for 30 days. Serum estrogen levels were measured. The knees were stripped of all soft tissue, and the load at failure for the anterior cruciate ligament was measured in a materials testing machine with a displacement rate of 0.5 mm/sec. The load at failure for all 16 specimens in Group E (446 ± 54 N) (mean ± SD) was significantly reduced (p = 0.02) compared with that for the nine specimens in Group O (503 ± 48 N). It is recognized that an increased number of anterior cruciate ligament injuries occurs in female athletes. Although the mechanism responsible for failure of the anterior cruciate ligament in women is yet to be defined, this experiment suggests that estrogen may alter ligament strength.
Influences of inflation rate and duration on vasodilatory effect by intermittent pneumatic compression in distant skeletal muscle
Authors: Liu Kang , Chen Long‐En , Seaber Anthony V. , Urbaniak James R. 
Published: February 2005

AbstractPrevious study has demonstrated that application of intermittent pneumatic compression on legs can cause vasodilation in distant skeletal muscle at the microcirculation level. This study evaluated the influence of inflation rate and peak‐pressure duration on the vasodilatory effects of intermittent pneumatic compression. The cremaster muscles of 50 male rats were exposed and divided into five groups of 10 each. A specially designed intermittent pneumatic‐compression device was applied in a medial‐lateral fashion to both legs of all rats for 60 minutes, with an inflation rate and peak‐pressure duration of 0.5 and 5 seconds, respectively, in group A, 5 and 0 seconds in group B, 5 and 5 seconds in group C, 10 and 0 seconds in group D, and 10 and 5 seconds in group E. Diameters of arterial segments were measured in vessels of three size categories (10–20, 21–40, and 41–70 μm) for 120 minutes. The results showed that the greatest increase in diameter was produced by intermittent pneumatic compression with the shortest inflation rate (0.5 seconds). A moderate increase resulted from compression with an inflation rate of 5 seconds, and no effective vasodilation occurred during compression with the longest inflation rate (10 seconds). When the groups with different inflation rates but the same peak‐pressure duration were compared, there was a significant difference between any two groups among groups A, C, and E and between groups B and D. When the groups with different peak‐pressure durations but the same inflation rate were compared, compression with a peak‐pressure duration of 5 seconds caused a generally similar degree of diameter change as did compression without inflation at peak pressure. The findings suggest that inflation rate plays an important role in the modulation of distant microcirculation induced by intermittent pneumatic compression whereas peak‐pressure duration does not significantly influence the vasodilatory effects of the compression. This may be due to the fact that rapid inflation produces a significant increase in shear stress on the vascular wall, which stimulates vascular endothelium to release nitric oxide, causing systemic vasodilation.
Tensile properties of articular cartilage are altered by meniscectomy in a canine model of osteoarthritis
Authors: Elliott Dawn M. , Guilak Farshid , Parker Vail T. , Wang Jean Y. , Setton Lori A. 
Published: February 2005

AbstractLoss of or damage to the meniscus alters the pattern of loading in the knee joint and frequently leads to cartilage degeneration and osteoarthritis. The mechanical properties of articular cartilage have been shown to reflect the extent of cartilage degeneration in human osteoarthritis and in experimental models of joint disease, but there is little experimental data documenting changes in cartilage mechanics following meniscectomy. We hypothesized that the tensile properties of the surface zone of articular cartilage are altered following total medial meniscectomy. Twelve mongrel dogs underwent complete resection of the medial meniscus in the right knee, and the femoral cartilage was studied 12 weeks after the operation. We performed uniaxial, tensile stress‐relaxation tests to determine the equilibrium tensile modulus of surface‐zone cartilage. Water and glycosaminoglycan content were also measured at site‐matched locations. The tensile moduli of the cartilage decreased significantly following meniscectomy. The linear region modulus decreased by 40%, from 25.5 ± 7.7 to 15.3 ± 7.2 MPa. There was a weak (r = −0.45), but significant, correlation between the linear region modulus and the gross morphological grade for cartilage damage. Water and glycosaminoglycan content did not change following meniscectomy. Composition was not correlated with mechanical properties or morphological grade, suggesting that cartilage structure may play a more important role than composition in determining the mechanical properties. The observed decrease in cartilage material properties provides a quantitative measure of the loss of cartilage function following meniscectomy and reflects a pattern of change that is consistent with damage to the collagen‐proteoglycan solid network.
Dynamic measurement of bone blood perfusion with modified laser doppler imaging
Authors: Chan Roxane C. , Forrester Kevin , McDougall Jason J. , Bray Robert C. , Zernicke Ronald F. 
Published: February 2005

AbstractAlthough the mechanisms are not clearly defined, blood flow may play an important role in moderating skeletal adaptation. Most techniques currently available to measure blood flow in bone are time‐consuming and require destruction of the tissue, but laser Doppler technology offers a less invasive method. The present study assessed whether laser Doppler perfusion imaging could detect changes in perfusion in cortical bone. By use of modified laser Doppler perfusion imaging with an adjustable, incorporated, near infrared‐laser gain photodetection system, perfusion of blood in the mid‐diaphyseal tibial cortex of New Zealand White rabbits (n = 5) was measured before, during, and after occlusion of the femoral artery. During occlusion, perfusion decreased 69% compared with control levels; removal of the arterial clip caused flux values to return to near normal. Laser Doppler perfusion imaging provides a two‐dimensional image related to blood flow, and the results of this pilot study suggest that it may be an effective technique for imaging in vivo dynamic changes in perfusion in cortical bone.
Pertussis toxin‐sensitive G proteins as mediators of stretch‐induced decrease in nitric‐oxide release of osteoblast‐like cells
Authors: Hara Fumihiko , Fukuda Kanji , Ueno Mitsuo , Hamanishi Chiaki , Tanaka Seisuke 
Published: February 2005

AbstractMechanical loading plays an important role in regulating bone remodeling, and nitric oxide may be one regulator of this process. To determine how mechanical stress modulates osteoblast function, we loaded cyclic tensile stretch on osteoblast‐like cells and measured levels of nitric oxide in the medium. High frequency of stretch at any magnitude inhibited release of nitric oxide; however, low frequency of stretch enhanced its release from the static control. To examine the involvement of G protein (guanine nucleotidebinding regulatory protein) in stress‐inhibited release of nitric oxide, we added pertussis toxin, a specific inhibitor of the Gi class, and found that it completely reversed the stress‐inhibited release. These data support the idea that pertussis toxin‐sensitive G protein is activated in the presence of cyclic tensile stretch.
Novel formulation of fibroblast growth factor‐2 in a hyaluronan gel accelerates fracture healing in nonhuman primates
Authors: Radomsky Michael L. , Aufdemorte Thomas B. , Swain Larry D. , Casey Fox W. , Spiro Robert C. , Poser James W. 
Published: February 2005

AbstractRecent advances in understanding the biology of fracture healing and the availability of specific macromolecules has resulted in the development of novel treatments for injuries to bone. Fibroblast growth factor‐2 or basic fibroblast growth factor (4 mg/ml), a potent mitogen, and hyaluronan (20 mg/ml), an extra‐cellular matrix component, were combined into a viscous gel formulation intended for direct, percutaneous injection into fresh fractures. In an experimental primate fracture model, a bilateral 1‐mm‐gap osteotomy was surgically created in the fibulae of baboons. A single direct administration of this hyaluronan/fibroblast growth factor‐2 formulation to the defect site significantly promoted local fracture healing as evidenced by increased callus formation and mechanical strength. Radiographic analysis showed that the callus area was statistically significantly larger at the treated sites than at the untreated sites. Specimens treated with 0.1, 0.25, and 0.75 ml hyaluronan/fibroblast growth factor‐2 demonstrated a 48, 50, and 34% greater average load at failure and an 82, 104, and 66% greater energy to failure than the untreated controls, respectively. By histologic analysis, the callus size, periosteal reaction, vascularity, and cellularity were consistently more pronounced in the treated osteotomies than in the untreated controls. These results suggest that hyaluronan/fibroblast growth factor‐2 may provide a significant advance in the treatment of fractures.
Osteoclastogenesis is repressed by mechanical strain in an in vitro model
Authors: Rubin J. , Fan X. , Biskobing D. M. , Taylor W. R. , Rubin C. T. 
Published: February 2005

AbstractFunctional loading provides a site‐specific signal for the regulation of bone mass and morphology. To determine if strain can inhibit the resorptive component of bone remodeling, osteoclast formation was assessed in marrow cultures plated on flexible membranes subjected to 5% strain for 10 cycles/minute, 24 hours per day. Cultures strained during days 2 through 7 inhibited osteoclast formation to 61 ± 7% of control cultures (P < 0.05), a degree of inhibition similar to that observed when the cultures were subjected to strains during only days 2 through 4 but also evaluated on day 7 (67 ± 4% of control; p < 0.05). In contrast, straining of cultures during days 5 through 7 had little influence on inhibiting the formation of osteoclasts (94 ± 5% of control; no significant difference). The nonuniformly strained substrate was subdivided into three concentric rings, and cultures were used to examine the site‐specificity of the inhibition caused by strain. Osteoclast formation in the outermost boundary, Which was distended from 3.6 to 5%, was 41 ± 7% of that observed in outer regions of control wells. The inhibitory potential of mechanical strain was reduced within the middle ring (73 ± 6% of control osteoclasts: p < 0.01). where the strain ranged from 0.2 to 3.6%. The central region, which experienced strains equivalent to those in the middle ring (0.2 to ‐4% strain), showed inhibition of osteoclast formation to a similar degree (75 ± 6% of control). Media harvested from strained cultures failed to inhibit osteoclast formation in unstrained cultures; this implies that the inhibitory effect of strain depended on the direct interaction of the cell with the substrate rather than by a humoral factor. A second device, where a uniform strain was delivered at 1.8% throughout the entire plate, inhibited osteoclast recruitment to 48 ± 3.6%, emphasizing that uniform strain in the absence of shear stress constrains osteoclast recruitment. These in vitro experiments can but model the complex environment generated by in vivo mechanical strains; however, they provide the first direct evidence that strain must be considered as inhibitory to osteoclast recruitment.
Step activity monitor: Increased accuracy in quantifying ambulatory activity
Authors: Shepherd Eric F. , Toloza Eileen , McClung Christian D. , Schmalzried Thomas P. 
Published: February 2005

AbstractThis study compares the accuracy of a two‐dimensional accelerometer worn on the ankle (a step activity monitor) with that of an electronic, digital pedometer worn on the belt line. Twenty‐nine human subjects were evaluated while they briskly walked 400 M, slowly walked 10 M, and ascended and descended a flight of stairs. The step activity monitor had less error in all activities; its mean absolute error was 0.54%, whereas that of the pedometer was 2.82%. The difference was more pronounced in obese subjects (body mass index greater than 30), with an overall mean absolute error of 0.48% for the step activity monitor and 6.12% for the pedometer (nearly 13 times that of the step activity monitor). For subjects with a body mass index less than 30, the step activity monitor had an overall error of 0.56% and the pedometer had an overall error of 1.56% (less than 3 times that of the step activity monitor). The absolute error of the pedometer was positively correlated with body mass index (r = 0.792, p < 0.0001) and weight (r = 0.753, p < 0.0001), whereas the error of the step activity monitor was not significantly correlated with either. Neither device was significantly biased by age, gender, or the presence of a lower‐extremity joint prosthesis. The accuracy and additional capabilities, including a real‐time memory record of activity, of the step activity monitor make it well suited for objectively quantifying ambulatory activity, especially for obese subjects.
Ultrasonographic measurement of the mechanical properties of the sole under the metatarsal heads
Authors: Wang Chung‐Li , Hsu Tsz‐Ching , Shau Yio‐Wha , Shieh Jeng‐Yi , Hsu Kuang‐Hung 
Published: February 2005

AbstractThe sole under the metatarsal heads functions as a shock absorber during walking and running. The mechanical properties of the sole provide the primary defense against the development of metatarsalgia and foot ulceration. However, limited information about these properties has been documented. In this study, we used ultrasonography to evaluate the mechanical properties, including unloaded thickness, compressibility index, elastic modulus, and energy dissipation ratio, of the sole in 20 healthy subjects. The unloaded thickness decreased progressively from the first to the fifth metatarsal heads, with values of 1.50, 1.36, 1.25, 1.14, and 1.04 cm. The sole under the first metatarsal head had the greatest values for the compressibility index and elastic modulus (55.9% and 1.39 kg/cm2), and the sole under the third metatarsal head had the smallest values (50.8% and 1.23 kg/cm2). The sole under the fifth metatarsal head had the greatest energy dissipation ratio (33.7%), followed by that under the third, second, first, and fourth metatarsal heads. Multivariate adjusted linear regression showed that the unloaded thickness, compressibility index, and elastic modulus values increased significantly with age and body weight (p < 0.05) and that the energy dissipation ratio increased significantly with body weight (p < 0.05).
Shear mechanical properties of human lumbar annulus fibrosus
Authors: Iatridis James C. , Kumar Sanjay , Foster Robert J. , Weidenbaum Mark , Mow Van C. 
Published: February 2005

AbstractFunction, failure, and remodeling of the intervertebral disc are all related to the stress and strain fields in the tissue and may be calculatd by finite element models with accurate material properties, realistic geometry, and appropriate boundary conditions. There is no comprehensive study in the literature investigating the shear material properties of the annulus fibrosus. This study obtained shear material properties of the annulus fibrosus and tested the hypothesis that these properties are affected by the amplitude and frequency of shearing, applied compressive stress, and degenerative state of the tissue. Cylindrical specimens with an axial orientation from seven nondegenerated and six degenerated discs were tested in torsional shear under dynamic and static conditions. Frequency sweep experiments over a physiological range of frequencies (0.1‐100 rad/sec) at a shear strain amplitude of 0.05 rad were performed under three different axial compressive stresses (17.5, 25, and 35 kPa). At the largest compressive stress, shear strain sweep experiments (strain amplitude range: 0.005‐0.15 rad at a frequency of 5 rad/sec) and transient stress‐relaxation tests (shear strain range: 0.02‐0.15 rad) were performed. The annulus fibrosus material was less stiff and more dissipative at larger shear strain amplitudes, stiffer at higher frequencies of oscillation, and stiffer and less dissipative at larger axial compressive stresses. The dynamic shear modulus, |G*|, had values ranging from 100 to 400 kPa, depending on the experimental condition and degenerative level. The shear behavior was also predominantly elastic, with values for the tangent of the phase angle (tanδ) ranging from 0.1 to 0.7. The annulus material also became stiffer and more dissipative with degenerative grade; however, this was not statistically significant. The results indicated that nonlinearities, compression/shear coupling, intrinsic viscoelasticity, and, to a lesser degree, degeneration all affect the shear material behavior of the annulus fibrosus, with important implications for load‐carriage mechanisms in the intervertebral disc. These material complexities should be considered when choosing material constants for finite element models.
Gene expression in menisci from the knees of skeletally immature and mature female rabbits
Authors: Le Graverand Marie‐Pierre Hellio , Reno Carol , Hart David A. 
Published: February 2005

AbstractThis study, using the sensitive molecular technique of semiquantitative reverse transcription‐polymerase chain reaction, evaluated mRNA levels for several molecules in medial and lateral menisci from the knees of skeletally mature and immature rabbits. Total RNA was extracted from the medial and lateral menisci of New Zealand White rabbits with the TRIspin method. Total RNA and DNA were similar in the two menisci of both immature and mature rabbits. The total RNA was reverse‐transcribed and analyzed by semiquantitative polymerase chain reaction using rabbit‐specific primer sets; levels of mRNA for a subset of molecules differed between the medial and lateral menisci. These variations in mRNA levels were also influenced by the degree of skeletal maturity of the rabbits. For most of the genes, mRNA levels were generally higher in the medial than in the lateral meniscus. The medial meniscus from immature and mature rabbits had significantly increased levels of mRNA for molecules such as transforming growth factor‐β, cyclooxygenase‐2, and tissue inhibitor of metalloprotease‐1. In contrast, compared with mRNA in the lateral meniscus, that for types II and III collagen, biglycan, insulin‐like growth factor‐2, plasminogen activator inhibitor‐1, and matrix metalloprotease‐1 was significantly increased in the medial meniscus of mature rabbits only and that for versican and type‐I collagen was significantly increased in the medial meniscus of immature rabbits only. Levels of mRNA for inducible nitric oxide synthase and basic fibroblast growth factor were similar in both menisci for both age groups. The present study demonstrates that regulation of mRNA levels in medial and lateral menisci is tissue‐specific and influenced by the skeletal maturity of the animals.
PT‐12, a putative ras‐activated proliferation‐dependent gene, is expressed in patellar tendon and not in anterior cruciate ligament
Authors: Goomer R. S. , Maris T. , Ostrander R. , Amiel D. 
Published: February 2005

AbstractWe describe a gene (PT‐12) that is expressed in the patellar tendon and not in the anterior cruciate ligament. We used a recently developed polymerase chain reaction‐based subtractive cDNA analysis to discover genes that are overexpressed in the patellar tendon but not expressed in the anterior cruciate ligament; the long‐term objective was to find genes that are central to the self‐repair of the patellar tendon, in contrast with the inability of the anterior curciate ligament to launch a repair response following injury. PT‐12 is a homologue of human S2 or mouse LLRep3 ribosomal genes, which are known to be overexpressed in highly proliferating cells. This study opens a new vista to the development of techniques and reagents to study the differences between two periarticular tissues (i.e., the patellar tendon and anterior cruciate ligament) that differ primarily in their ability to self‐repair.