bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental method for the measurement of the elastic modulus of trabecular bone tissue
Authors: Mente P. L. , Lewis J. L. 
Published: February 2005

AbstractA procedure has been developed to measure the elastic modulus of small, irregularly shaped specimens without significantly disturbing the specimen's internal or surface structure. This procedure was developed to measure the average elastic modulus of isolated trabeculae from human cancellous bone tissue. The procedure combines direct testing of a cantilever beam‐type specimen, along with finite element modeling of the specimen and the testing conditions. Initial estimates for the bone tissue material properties are input into the finite element model; differences between the calculated finite element displacement and the experimentally observed displacement allows the actual material modulus to be determined. Machined aluminum and cortical bone specimens were used to test the accuracy and repeatability of the procedure. Manipulations of the finite element models were performed to examine the effect that mesh construction errors might have on the accuracy of the results. None of the parameters examined resulted in changes in the measured finite element displacements of greater than 8%. In tests on six trabecular bone speciments, an average elastic modulus of 7.8 GPa was calculated. Even taking into account the possible sources of error, this value remains significantly less than the accepted value for cortical bone.
“Benign” metastasizing giant cell tumor: Evaluation of nuclear DNA patterns by flow cytometry
Authors: Scott Steven M. , Pritchard Douglas J. , Unni K. Krishnan , Rainwater Leslie M. , Lieber Michael M. 
Published: February 2005

AbstractNuclear deoxyribonucleic acid (DNA) ploidy was determined by flow cytometry for nine histologically benign giant cell tumors that developed systemic metastases and for eight tumors that did not metatasize. Specimens from the primary tumor, local recurrences, and pulmonary metastases were evaluated. No feature of the DNA ploidy pattern was identified to distinguish giant cell tumors that metastasized from those did not. The mean percentage of diploid (G0/G1 peak, 2C) cells was 81% in the metastasizing group and 80% in the nonmetastasizing group. The DNA ploidy pattern of the primary tumors was not different from that of their metastases. No DNA aneuploid patterns were observed among the benign tumors.
Intraarticular pressure during continuous passive motion of the human knee
Authors: Pedowitz R. A. , Gershuni D. H. , Crenshaw A. G. , Petras S. L. , Danzig L. A. , Hargens A. R. 
Published: February 2005

AbstractIntraarticular pressure (IAP) was continuously monitored during continuous passive motion (CPM) of five normal and 11 abnormal human knees using a new fiberoptic, transducer‐tipped Camino catheter. IAP varied in a consistent hysteresis pattern in the normal knees, with subatmospheric pressures recorded at intermediate angles of joint flexion. A similar pattern was recorded in the abnormal knees without cruciate ligament pathology, whereas considerable variability was noted in the knees with cruciate ligament abnormality. IAP was lower in the extension to flexion than in the flexion to extension portion of the CPM cycle, providing evidence of intraarticular fluid flow during portions of the CPM cycle. IAP changes were consistent with “physiologic compartmentation” within the knee at extremes of joint position. Capsular viscoelastic changes and/or synovial fluid volume changes were observed during CPM. The therapeutic mechanism of continuous passive motion may be related to cyclic variation of the intraarticular pressure.
Three‐phase [99mTc]diphosphonate scintimetry in septic and nonseptic arthritis of the immature knee: An experimental investigation in dogs
Authors: Hansen Ebbe Stender , Hjortdal Vibeke Elisabeth , Noer Ivan , Holm Ida Elisabeth , Ewald Henrik , Bünger Cody 
Published: February 2005

AbstractWe compared the informative value of dynamic and static [99mTc]diphosphonate ([99mTc]DPD) scintimetry in early septic arthritis (SA) and chronic nonseptic arthritis (NSA) of the knee in puppies. SA (n = 10), induced by injection of Staphylococcus aureus into one knee, was examined after 48 h. NSA (n = 6) was induced by weekly intraarticular instillation of 1% carragheenan and examined at 2 and 12 weeks. Epiphyseal and metaphyseal count ratios (CRs) between experimental and control joint were calculated in an angiographic phase (0–20 s), a “blood pool” phase (20–256 s), and a bone uptake phase (2 hs). Control dogs (n = 4) had a CR of 1.0 in all regions and phases, the coefficients of variation being 0.06 and 0.03 in dynamic and static phases, respectively. In NSA, all scintimetric phases showed decreased meytaphyseal uptake and largely unchanged epiphyseal uptake. Generally, SA exhibited vastly increased angiographic uptake in all regions and increased epiphyseal blood pool uptake, whereas delayed epiphyseal uptake varied and delayed metaphyseal uptake tended to decrease. Two septic joints had generalized reduction in dynamic uptake probably owing to increased intraarticular pressure; in one of these, dynamic uptake in the distal femoral epiphysis (FE) was totally absent, suggesting temporary circulatory arrest during the dynamic scanning procedure. The use of regional dynamic and static [99mTc]DPD scintimetry increased the pathophysiologic and diagnostic value of joint scintigraphy, especially with respect to the early detection of SA and its avascular complications.
Anterior cruciate ligament: Its normal response and replacement
Authors: Butler David L. 
Published: February 2005

AbstractThis article reviews our research studies on the anterior cruciate ligament (ACL). The human ACL was found to be a primary restraint to anterior tibial displacement at both 90° and 30° of flexion. Geometric measurements of the ligament showed it to have a complex macrostructure, consisting of bundles of different lengths, curvatures, and orientations. Similar material properties were measured for subunits from the human anterior and posterior cruciate and lateral collateral ligaments. However, the linear modulus, maximum stress, and strain energy density to maximum stress of the ACL were significantly less than similar properties for patellar tendons. These tissue subunits exhibited nonuniform axial strain during tensile loading, which was partially attributed to differences in bundle crimp period and crimp angle. The structural mechanical properties (stiffness, strength, and energies and elongations to maximum force and failure) of nine commonly used human ACL substitutes were also compared. Only the bone‐patellar tendon‐bone unit had maximum force and stiffness greater than that of the ACL. The patellar tendon, when used as an ACL replacement in the dog and primate, exhibited significant loss in structural mechanical and material properties early after implantation. These properties showed only a gradual improvement up to 1 year after surgery. Maintaining a vascular supply to these grafts or using intermittent passive motion immediately after surgery produced no significant improvement in graft properties in the primate model.
Collagen synthesis during primate flexor tendon repair in vitro
Authors: Russell Jean E. , Manske Paul R. 
Published: February 2005

AbstractThe concept that flexor tendons have the intrinsic capacity to participate actively in the repair process following laceration has been developed in recent years as the result of experimental studies from numerous laboratories. However, the role of the outer/epitenon and inner/endotenon cell populations with regard to protein synthesis is still controversial. The purpose of this study was to investigate the respective participation of these tendon fibroblast populations in the synthesis of the collagen matrix during in vitro repair of the flexor tendon from nonhuman primates, utilizing immunohistochemical techniques and a Type I procollagen antibody. Zone II profundus flexor tendon segments were obtained from young adult Macaca nemestrina monkeys. One centimeter segments were cultured either with or without a transverse laceration across 90% of the midsection of the tendon segment. Frozen sections of the cultured tendon segments were reacted with the (mouse monoclonal) Type I procollagen antisera. At all times of culture of the nonlacerated tendon segment, only a few of the epitenon cells along the surface of the tendon and distant from the cut end stained positively for active collagen synthesis. In the lacerated segments, and as early as 9 days of culture and repair, the procollagen reaction product was starting to appear in those cells of the outer epitenon cell layer. These studies support the concept that the inner fibroblasts do actively participate in collagen production. However, it now also appears that a significant degree of collagen synthesis during tendon repair resides in the outer/epitenon layer of cells enveloping the tendon segment, and that the repair response of the flexor tendon in vitro is proportional to the degree of injury.
Participation of human superficialis flexor tendon segments in repair in vitro
Authors: Mass Daniel P. , Tuel Robert J. 
Published: February 2005

AbstractWe analyzed the healing capability of the human superficialis (sublimus) flexor tendon in response to injury in vitro by performing a morphologic study of tendon repair. Tendon segments were cultured in cell‐free medium for 2, 4, or 8 weeks, and the cut‐end repair sites were compared with those in fresh control segments on light and electron microscopy. Tendon encapsulation had occurred at 2 weeks, by the proliferation and migration of elongated fibroblasts from the epitenon and from collagen bundles of the endotenon to cover the surface of the cut tendon ends. As migrating epitenon cells approached the cut margin, they consistently shifted from a parallel to a circumferential orientation with respect to the tendon axis. By 4 weeks, the encapsulating surface cells had lost their membranous ruffles and had become flattened. Within the capsule, phagocytic cells engulfed collagen debris, and fibroblasts containing extensive rough endoplasmic reticulum profiles and secretory vesicles participated in protein synthesis. The surface of the capsule was smooth and, at 8 weeks, was almost indistinguishable from the epitenon surface of uncultured controls. The capsule now had a collagen‐synthesizing layer of fibroblasts superimposed on layers of maturing collagen bundles that separated restingphase fibroblasts. These findings demonstrate that segments of human superficialis flexor tendons participate in an intrinsic repair response without contributions from extrinsic cells.
The effect of shear fatigue on bovine articular cartilage
Authors: Simon William H. , Mak Arthur , Spirt Adrienne 
Published: February 2005

AbstractThe objective of this study was to investigate the effects of mechanical fatigue in the form of cyclic shear strain on articular cartilage. Three millimeter diameter full‐thickness plugs were cored from the lateral aspect of bovine tibial plateaus. Sinusoidal shear strains of ±5, ±10, and ±15% were applied to the specimens at 100 Hz for 3 h (a total of 108 ±X 104 cycles). The mechanical shear properties of the tissue (loss and storage moduli) were determined as a function of the number of applied strain cycles. A rapid, irreversible decrease of approximately 35% of initial modulus was found to occur in both loss and storage modulus during application of the first 90,000 cycles. Further decay in the moduli was found to occur from 90 ±X 103 to 108 ±X 104 cycles, but was of considerably smaller magnitude than the initial decrease. The moduli remained relatively constant beyond application of 108 ±X 104 cycles. No consistent change in proteoglycan content was found to be associated with the fatigue process when comparing tested specimens with fresh untested tissue, and with experimental controls. In addition, no structural defects in the mechanically altered tissue were revealed by scanning electron microscopy.
Effect of doxorubicin on local recurrence following marginal resection in the MGH‐OGS murine model
Authors: Bell R. S. , O'Connor G. , Bell D. F. , Jacob J. 
Published: February 2005

AbstractDespite the fact that preoperative chemotherapy causes substantial necrosis in the primary osteosarcoma tumor, most authorities recommend resecting these lesions with a wide margin of normal tissue to avoid local recurrence. This study evaluated the effect of systemic chemotherapy (doxorubicin) on tumor growth and histology in the MGH‐OGS transplantable murine model and examined whether this drug prevents local recurrence after resection of the tumor with positive microscopic margins. The results indicate that doxorubicin caused prolonged cessation of tumor growth, produced substantial necrosis within the lesion, and decreased the risk of local relapse following marginal surgery. The drug effect was dose‐dependent and drug efficacy in preventing local relapse was maximal with administration prior to or at the time of surgery.
Transcortical streaming potentials are generated by circulatory pressure gradients in living canine tibia
Authors: Otter M. W. , Palmieri V. R. , Cochran G. V. B. 
Published: February 2005

AbstractElectrical potentials associated with the pulse pressure have been observed in a canine tibia model in vivo. As the medullary pressure rises during pulsing, the periosteal bone surface becomes positive with respect to the endosteal surface. This pattern is consistent with streaming potentials generated by outward flow of fluid through bone with a negatively charged matrix (negative zeta potential). Both the medullary pressure and electric potential oscillations are halted by occlusion of the femoral artery. Furthermore, systemic administration of epinephrine decreases the amplitude of the medullary pressure and the electric potential by the same fraction. Streaming potentials generated by blood flow are distinct from those generated by mechanical deformation and may have additional significance in relation to fracture healing and/or etiology of osteoporosis.
Repair of cartilaginous fractures during chick limb development
Authors: McCullagh J. J. , Gill P. , Wilson D. J. 
Published: February 2005

AbstractThe embryonic chick wing has been used extensively in experimental analyses of the mechanisms involved in limb development. This study employs the embryonic wing in an examination of the possible origin of congential pseudoarthrosis, a poorly understood limb disorder. To this end, chick radii were fractured in the middiaphysis prior to the onset of osteogenesis (6.5–7 days of incubation). The subsequent development of the fractured elements was examined using both whole mount preparations and histology. Callus cartilage did not form around any of the fractures. Nonetheless, the majority (29 of 33 specimens) of fractures united during primary osteogenesis (within 24–36 h of the operation), with bone formation occurring both across the fracture site and also over the cut ends of the cartilage. In addition, bones that exhibited a configuration, similar to that described as giving rise to a type II congenital pseudoarthrotic condition were obtained. Typically, these bones showed an “hourglass” constriction midshaft and anterior bowing. These results suggest that the embryonic chick limb may serve as a useful experimental model system for the investigation of this congenital limb disorder.
Resistance of a defect of the supraspinatus tendon to intraarticular hydrodynamic pressure: An experimental study on rabbits
Authors: Björkenheim Jan‐Magnus , Paavolainen Pekka , Ahovuo Juhani , Slätis Pär 
Published: February 2005

AbstractThe healing of a standardized defect of the supraspinatus tendon in a time‐related series on rabbits was monitored with arthrography and simultaneous determination of the intra‐articular hydrodynamic pressure of the glenohumeral joint. All normal glenohumeral joints produced a biphasic pressure versus volume curve. Rupture of a normal glenohumeral joint occurred at a pressure level of 140–170 mm Hg and was located in the area around the biceps tendon sheath. In joints with a defect of the supraspinatus tendon, leakage of the contrast medium was evident up to the sixth week, at an intra‐articular pressure varying from 40 to 100 mm Hg. After week 6, no leakage of the cuff was seen during the determination of the intraarticular pressure. This was in accordance with the histological findings: the defect was covered with solid scar tissue from the ninth week onward. Resistance to hydrodynamic intra‐articular pressure proved a reliable method of determining the strength of the healing of the supraspinal defects.
Comparison of the effects of adriamycin and methotrexate on orthotopic and induced heterotopic bone in rats
Authors: Nilsson Olle S. , Bauer Henrik C. F. , Brostrōm Lars‐Åke 
Published: February 2005

AbstractThe effect of the two antineoplastic drugs, Adriamycin and methotrexate, on orthotopic bone, and on the induction of experimental heterotopic bone in rats was analyzed. The drugs were administered as single injections: Adriamycin in s.c. doses of 0.5 and 2 mg/kg body weight and methotrexate i.v. 100 and 250 mg/kg body weight followed by leucovorin rescue after 2 h. A passing, but significant, decrease in body weights occurred in the methotrexate‐treated animals, but not in those given Adriamycin. Analysis of the amount of heterotopic bone formed 4 weeks after induction by demineralized bone matrix revealed a 30–40% decrease in the groups treated with either of the antineoplastic agents, whereas orthotopic bone was unaffected. Six weeks after the treatment the net effect on the induced bone had decreased. The present study shows that the two antineoplastic drugs Adriamycin and methotrexate inhibit heterotopic new bone formation induced by demineralized bone matrix in rats to an equal extent, although their mode of action on the cellular level is entirely different, and that the inhibitory effect of a single treatment diminishes in the presence of a continuous inductive process.
Effects of exercise on blood flow to canine articular tissues
Authors: Simkin Peter A. , Huang Alice , Benedict Richard S. 
Published: February 2005

AbstractWe measured articular blood flow by standard microsphere techniques in normal adult dogs at rest and during treadmill exercise. All animals but one underwent β‐adrenergic blockade as part of another experimental protocol. Expressed in μl/min/g ± SEM, baseline flow values to articular tissues were: knee synovium 26 ± 4, femoral condyle 130 ± 21, tibial plateau 182 ± 29, articular fat pad 9 ± 2, knee ligaments 17 ± 3, menisci 34 ± 6, wirst synovium 19 ± 4, distal radius 65 ± 13, and lunate bone 59 ± 13. Blood flow increased with exercise in all soft tissue of both the knee (stifle joint) and the wrist (radiocarpal joint). Geometric mean exercise/rest flow ratios ranged from a low of 1.44 (p < 0.05) in the menisci of the knee to a high of 7.25 (p < 0.001) in the synovium of the wirst. In contrast, blood flow did not rise in juxtaarticular bones and fell significantly in femoral condyles (mean flow ratio 0.71, p < 0.005). These findings indicate that articular soft tissues derive increased perfusion from the redistribution of blood flow that accompanies short‐term exercise. In contrast, flow to juxtaarticular bone does not increase under these conditions.
Statistical significance and statistical power in hypothesis testing
Authors: Lieber Richard L. 
Published: February 2005

AbstractExperimental design requires estimation of the sample size required to produce a meaningful conclusion. Often, experimental results are performed with sample sizes which are inappropriate to adequately support the conclusions made. In this paper, two factors which are involved in sample size estimation are detailed—namely type I (α) and type II (β) error. Type I error can be considered a “false positive” result while type II error can be considered a “false negative” result. Obviously, both types of error should be avoided. The choice of values for α and β is based on an investigator's understanding of the experimental system, not on arbitrary statistical rules. Examples relating to the choice of α and β are presented, along with a series of suggestions for use in experimental design.
Quantitation and relative distribution of extracellular matrix in Staphylococcus epidermidis biofilm
Authors: Van Pett K. , Schurman D. J. , Smith R. Lane 
Published: February 2005

AbstractThe relationship between adherence of bacteria to foreign boides and their deposition of extracellular matrix was examined on glass and suture material. To quantitate bacterial adherence, uptake of [3H] thymidine into bacterial DNA was analyzed. Corresponding amounts of extracellular matrix were measured by a new technique using [14C]glucose incorporation. This study shows that [14C]glucose preferentially labeled bacterial strains in proportion to biofilm production. The ratio of 3H14C in high biofilm producers was 0.9 and in low producers it was 3.7. Radioactive identification of organisms as high and low producers was confirmed byelectron microscopy. The results presented here show that production and accumulation of biofilm over time is a stable characteristic in different strains of S. epidermidis. The use of ratios reflecting radiolobeling of bacteria and biofilm by [3H]thymidine and [14C]glucose, respectively, is a quantitative yet simple technique to assess extracellular matrix of different strains of S. epidermidis.
Effects of isolated rheumatoid synovial cells on cartilage degradation in vitro
Authors: Keller Kenneth , Shortkroff Sonya , Sledge Clement B. , Thornhill Thomas S. 
Published: February 2005

AbstractRheumatoid synovium in coculture with cartilage has been shown to release a factor(s) that stimulates the depletion of glycosaminoglycans (GAG) from cartilage matrix. Human rheumatoid synovium was enzymatically disaggregated and the isolated cells were subjected to a variety of mechanical and immunological treatments. Synovial cell conditioned media (SCCM) were prepared and analyzed for their ability to stimulate GAG depletion. SCCM prepared from increasing concentrations of isolated synovial cells demonstrated cartilage degradative activity in a dose‐dependent manner. This activity was characterized as interleukin‐l like and was found mostly within the adherent cell population where the synovial macrophages retained significant degradative ability. T cells alone were found to have no direct degradative effect on cartilage, but their presence appeared to augment the response of the adherent cells. The techiques described here provide a quantitative model for examining the degradative factors from synovium as well as the cellular interactions that promote their release.