bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microhardness and anisotropy of the vital osseous interface and endosseous implant supporting bone
Authors: Huja S. S. , Katona T. R. , Moore B. K. , Roberts W. E. 
Published: February 2005

AbstractLimited information is available on the mechanical properties of the rapidly remodeling bone that surrounds endosseous implants. Fifteen implant‐bone blocks were obtained from the mid‐femoral diaphyses of three mature male hounds 12 weeks after placement of the implants. To evaluate the microhardness and cortical anisotropy of bone, the implants were sectioned along their long axes. In this process, the femurs were sectioned transversely. Knoop microhardness measurements (HK) were made with a 50 g force on cortical bone and a 25 g force on periosteal callus, endocortical callus, and circumferential lamellar bone. The long diagonal of the indenter was placed parallel to the implant (in the radial bone direction). Measurements were made in cortical bone at 200, 400, 600, 800, 1,000. 1,500. 2,000. and 2,500 μm from both sides of the implant. To detect cortical anisotropy in the radial compared with the tangential direction, a second set of indentations was made perpendicular to the first. Microhardness of periosteal callus and endocortical callus and anisotropy of circumferential lamellar bone near the endocortical surfaces of the femur were also evaluated. Repeated measures analysis of variance showed significantly (p < 0.05) lower microhardness values (30.6 ± 0.8 HK [mean ± SEM]) for cortical bone at 200 μm than at any other location (range: 40.3–46.6 HK). Microhardness anisotropy was not detected in cortical bone. Furthermore, within 200 μm of the implant surface, the Knoop microhardness values were significantly lower for periosteal and endocortical calluses than for cortical bone. These data provide information about the mechanical properties of bone adjacent to endosseous implants at a microstructural level. The results are consistent with the high rate of remodeling seen adjacent to endosseous implants at 12 weeks after implantation.
Use of a bioabsorbable polymer for the delivery of ofloxacin during experimental osteomyelitis treatment
Authors: Nie Lin , Nicolau David P. , Tessier Pamela R. , Kourea Helen P. , Browner Bruce D. , Nightingale Charles H. 
Published: February 2005

AbstractThis study was performed to investigate the potential utility of ofloxacin‐impregnated bioabsorbable polymers for osteomyelitis therapy. Pseudomonas aeruginosa osteomyelitis was induced in 48 New Zealand White rabbits Four weeks after infection, the animals were randomized to one of four treatment groups: drug‐free polymer, ofloxacin polymer, systemic ofloxacin, or ofloxacin polymer plus systemic ofloxacin. Twentyeight days later, radiographs were taken of the affected area, the animals were killed, and bone was obtained for histoloeic evaluation. culture. and determination of ofloxacin concentrations. The percentage of sterile bone cultures was 33, 83, 75, and 91 for the groups treated with drug‐free polymer, ofloxacin polymer, systemic ofloxacin, and ofloxacin polymer plus systemic ofloxacin, respectively. When compared with the drug‐free polymer, both the ofloxacin polymer and the ofloxacin polymer plus systemic ofloxacin significantly improved the rate of sterilization. The mean concentrations of the drug in bone for the groups treated with ofloxacin polymer, systemic ofloxacin, and ofloxacin polymer plus systemic ofloxacin were 34.9 (range: 2–160), 1.9 (range: 0.8–3), and 26.0 μg/g (range: 9–100 μg/g), respectively. These data suggest that the DL‐lactide:glycolide polymer studied is a suitable vehicle for the delivery of high local concentrations of ofloxacin and that these concentrations result in eradication of the bacterial pathogen in this rabbit model.
Adenosine 5′‐triphosphate, uridine 5′‐triphosphate, bradykinin, and lysophosphatidic acid induce different patterns of calcium responses by human articular chondrocytes
Authors: Koolpe Mitchell , Rodrigo Juan J. , Benton Hilary P. 
Published: February 2005

AbstractSmall calcium‐mobilizing inflammatory mediators have been implicated in joint pathology. Here we demonstrate that bradykinin, adenosine 5′‐triphosphate, uridine 5′‐triphosphate, and lysophosphatidic acid raise the intracellular calcium concentration ([Ca2+]i) in human articular chondrocytes. Heterologous cross‐desensitization experiments showed that the uridine 5′‐triphosphate response was abolished by prior treatment with adenosine 5′‐triphosphate and conversely, that the adenosine 5′‐triphosphate response was abolished by prior treatment with uridine 5′‐triphosphate: this indicated competition for the same receptor site, whereas bradykinin and lysophosphatidic acid did not compete with other ligands. Pretreatment with thapsigargin abolished ligand‐mediated Ca2+ responses but not vice versa: this confirmed that Ca2+ release occurred from intracellular stores. Single‐cell analysis of Fura‐2 acetoxymethyl ester loaded chondrocytes showed mediator‐dependent patterns of oscillatory Ca2+ changes in a subset of cells when challenged with submaximal concentrations of bradykinin, adenosine 5′‐triphosphate, or uridine 5′‐triphosphate in the presence of extracellular Ca2+. However, no oscillatory responses were seen after a challenge with lysophosphatidic acid. Therefore, although a number of different Ca2+‐mobilizing ligands activate chondrocytes, the differences that occur in the temporal patterning of Ca2+ responses may result in unique mediator‐dependent changes in cellular activity.
Immunohistochemical detection of activin A, follistatin, and activin receptors during fracture healing in the rat
Authors: Nagamine Tomonori , Imamura Takeshi , Ishidou Yasuhird , Kato Mitsuyasu , Murata Fusayoshi , Dijke Peter ten , Sakou Takashi 
Published: February 2005

AbstractActivins are multifunctional proteins that belong to the transforming growth factor‐β superfamily and are thought to play an important role in modulating the formation of bone. Activins exert their cellular effects by way of activin type‐I and type‐II serine/threonine kinase receptors. Follistatin is an activin‐binding protein that can suppress the biological effects of activins. In this study, the immunohistochemical expression of activin A, follistatin, and activin receptors was studied during fracture healing in the rat. Activin A was weakly detected in the periosteum near the fracture ends at an early stage but was absent in the chondrocytes around the fracture gap, where endochondral ossification took place. An antibody to follistatin stained osteogenic cells in the periosteum near the fracture ends; moderate and strong staining were observed in proliferating, mature, and hypertrophied chondrocytes at the sites of endochondral ossification. Levels of activin A and follistatin were high near the posteoblasts on the surface of the newly formed trabecular bone. In addition, an intense localization of activin A was noted where multinucleated osteoclast‐like cells were present. This study suggests that the activin‐follistatin system may contribute to cellular events related to the formation and remodeling of bone during fracture healing. Activin type‐I and type‐II receptors were co‐expressed in intramembranous and endochondral ossification sites. The expression of activin type‐I, type‐II, and type‐IIB receptors in the absence of activin A in the endochondral ossification suggests that other isoforms of activins may signal by way of these receptors.
Viability of fibroblast‐seeded ligament analogs after autogenous implantation
Authors: Bellincampi Lisa D. , Closkey Robert F. , Prasad Rajiv , Zawadsky Joseph P. , Dunn Michael G. 
Published: February 2005

AbstractFibroblast‐seeded collagen scaffolds or ligament analogs are potentially useful for reconstruction of the anterior cruciate ligament of the knee. To provide lasting benefits, the seeded cells must survive implantation within the harsh synovial environment of the knee joint. Our objective was to determine the in vivo fate of autogenous fibroblast‐seeded ligament analogs as a function of fibroblast source (anterior cruciate ligament or skin), implantation site (knee joint or subcutaneous space), and time after implantation (1,2, 4, 6, or 8 weeks). Before implantation, fibroblasts were labeled with PKH26‐GL, a fluorescent membrane dye. Immediately after retrieval of the implant, the viability of the labeled seeded cells was assessed under a fluorescent microscope. Viable seeded fibroblasts remained attached to the collagen fibers within the ligament analogs for at least 4 weeks (skin fibroblasts) or 6 weeks (anterior cruciate ligament fibroblasts) after implantation. A larger number of viable seeded cells were consistently observed in the subcutaneous space than in the knee joint. Scaffold resorption prevented observation at the 8‐week time period. Fibroblast‐seeded ligament analogs remained viable for prolonged periods in the knee joint and therefore have the potential to influence the formation and remodeling of neoligament tissue after reconstruction of the anterior cruciate ligament.
Comparison of mRNA levels for matrix molecules in normal and disrupted human anterior cruciate ligaments using reverse transcription‐polymerase chain reaction
Authors: Lo Ian K. Y. , Marchuk Linda L. , Hart David A. , Frank Cyril B. 
Published: February 2005

AbstractMidsubstance samples of anterior cruciate ligaments from seven normal human cadaver knees (16–50 years old) were harvested and compared with midsubstance pieces of scarred anterior cruciate ligaments from 30 patients (15–40 years old). RNA was isolated from each ligament, and the expression of type‐I collagen, type‐III collagen, biglycan, decorin, lumican, and tissue inhibitor of metalloproteinase‐1 was evaluated by quantitative reverse transcription‐polymerase chain reaction with use of β‐actin as the housekeeping gene. Data for injured ligaments were further compared statistically as a function of time after injury to better define patterns of cellular expression over time. Our hypothesis was that injured ligaments would show minimal cellular activity and decreasing activity over time. The results revealed that both normal and injured anterior cruciate ligaments contain cells that express mRNA for all molecules studied. However, cells in Injured ligaments express much higher, but still proportional, quantities of message for type‐I collagen and, type‐III collagen (p < 0.000001) and higher quantities of biglycan (p < 0.02) and tissue inhibitor of metalloproteinase‐1 (p < 0.0003) than do cells in normal anterior cruciate ligaments. These levels remained elevated for longer than 1 year after injury. Linear regression analysis showed biglycan expression correlated with time from injury (r2 = –0.69; p = 0.007). These results collectively demonstrate that injured human anterior cruciate ligaments contain cells that express scar‐like molecules and that the injured ligaments are likely continuing to remodel matrix over time. Furthermore, they suggest that human anterior cruciate ligaments have not failed to heal due to the failure of scar formation per se. The quality and quantity of this scar remain questionable; however, the possibility of its enhancement as a healing strategy for human anterior cruciate ligaments cannot be dismissed.
Analysis of optimal range of socket orientations in total hip arthroplasty with use of computer‐aided design simulation
Authors: Seki Makoto , Yuasa Nobuhiro , Ohkuni Kyoko 
Published: February 2005

AbstractA three‐dimensional computer‐aided design model of a total hip replacement was used to study the effects of anteversion and abduction of the acetabular component and anteversion and varus‐valgus an‐gulation of the femoral component on the range of hip flexion and extension that could be obtained without component impingement. Impingement of the component was defined as impingement between the neck of the femoral component and the edge of the acetabular component. To achieve an angle of hip flexion greater than 90° and an extension angle greater than 30° without component impingement, the optimal angulations were found to be between 1 and 30° of anteversion and 30 and 50° of abduction of the acetabular component, as well as 10° of anteversion of the femoral component. When the valgus angulation of the femoral component was reduced from 7 to 0°, the allowable range of flexion without impingement increased under the. same conditions of acetabular‐component orientation and femoral‐component anteversion. Significant inverse correlations were found between the anteversion angle of the acetabular component and both the lumbar lordosis angle and the sacrohorizontal angle.
Computer model to predict subsurface damage in tibial inserts of total knees
Authors: Sathasivam S. , Walker P. S. 
Published: February 2005

AbstractTwo designs of total knee replacements were analysed to determine how the geometry of their bearing surface would affect the susceptibility of their ultra high molecular weight polyethylene tibial inserts to delamination. Orientations of the femoral components on the tibial surfaces were calculated with use of rigid body analysis for discrete intervals during the stance phase of gait. For each successive orientation, finite element analysis was used to compress the components together to determine the stresses in the tibial inserts. A damage function analogous to strain energy density was defined to account for the accumulated amplitudes, and frequencies of the maximum shear stress cycles and hence to predict fatigue failure. The damage function was applied to each polyethylene element in the tibial insert, and the highest value calculated for each design was its damage score. One knee had a damage score more than three times less than that of the other because of lower stresses and because the contact points moved in the medial‐lateral as well as anterior‐posterior directions during internal‐external rotation. The femoral and tibial components of this knee had lage outer frontal radii and close conformity in the frontal plane. We propose that this method, which accounts for the motions and stresses endured during walking, makes different predictions regarding the likelihood of delamination compared with the predictions made by conventional static compression tests performed when the knee is in a neutral position.
Chemotherapy and P‐glycoprotein expression in chondrosarcoma
Authors: Terek Richard M. , Schwartz Gary K. , Devaney Kenneth , Glantz Lisa , Mak Solida , Healey John H. , Albino Anthony P. 
Published: February 2005

AbstractChondrosarcomas are alleged to be resistant to chemotherapy. A retrospective review of our experience primarily with dedifferentiated chondrosarcomas treated with chemotherapy was performed to re‐evaluate the efficacy of chemotherapy for this tumor. There were 18 patients: 14 stage IIB and four stage III. Seventeen patients had dedifferentiated chondrosarcoma. The median age at diagnosis was 57 years. Fourteen of the patients underwent wide excision of the tumor, two underwent amputation, and two had no surgery. The femur and the pelvis were the most common locations of the primary tumor. Chemotherapy for 11 of the patients consisted of cisplatin and doxorubicin. Survival was analyzed with the Kaplan‐Meier method; the median survival was 12 months. The hypothesis that chondrosarcomas express P‐glycoprotein was tested. Expression of P‐glycoprotein was evaluated by immunostaining with use of the C494 and C219 antibodies on 41 benign and malignant cartilage tumors, six of which were from the patients in the chemotherapy group. Immunostaining revealed that 37 of 41 cartilage tumors expressed P‐glycoprotein. The rate of survival of patients with high‐grade chondrosarcoma treated with chemotherapy is poor. P‐glycoprotein expression is common in benign and malignant cartilage lesions. The lack of response to chemotherapy may be related to the expression of P‐glycoprotein.
Blood supply of the achilles tendon
Authors: Ahmed I. M. , Lagopoulos M. , McConnell P. , Soames R. W. , Sefton G. K. 
Published: February 2005

AbstractThe Achilles tendon is one of the most common sites of injury and rupture as a result of overuse. Evidence suggests that the pathogenesis of rupture could involve the pattern of its blood supply. With use of angiographic and histological techniques, the blood supply of the Achilles tendon was investigated in 12 human cadaveric specimens. Angiography confirmed Mayer's 1916 finding that the blood supply to the tendon is from three areas: the musculotendinous and osseotendinous junctions and the paratenon, with the posterior tibial artery providing the major contribution. However, qualitative and quantitative histological analyses in this study showed that the Achilles tendon has a poor blood supply throughout its length, as determined by the small number of blood vessels per cross‐sectional area, which do not in general vary significantly along its length. In light of these findings, it is suggested that poor vascularity may prevent adequate tissue repair following trauma, leading to further weakening of the tendon.
Pyridinoline in relation to ultimate stress of the patellar tendon during healing: An animal study
Authors: Chan Barbara P. , Fu S. C. , Qin L. , Rolf C. , Chan K. M. 
Published: February 2005

AbstractThe ultimate stress of the central one‐third of the patellar tendon was studied in a gap wound‐healing model in the rat. The specimens were also analyzed for collagen and nonreducible crosslinks, as measured by hydroxyproline and pyridinoline content, respectively. Thirty days after injury, the ultimate stress of the healing patellar tendon was restored to an average of 71% of the control value and remained constant over time. The pyridinoline content of the healing tendon was twice the control value by 30 days after injury and reached a plateau; however, the hydroxyproline content did not change significantly over time. Stepwise regression analysis demonstrated that pyridinoline was a better biochemical marker for ultimate stress than was hydroxyproline. The current study provides insights into the functional behaviour of the healing patellar tendon by establishing the relationship between the two biochemical components and the ultimate stress of the healing patellar tendon. This study also suggests the possibility of using pyridinoline content as an indirect marker of the ultimate stress because in vivo assessment is impossible.
Finite‐element modeling of trabecular bone: Comparison with mechanical testing and determination of tissue modulus
Authors: Ladd Anthony J. C. , Kinney John H. , Haupt David L. , Goldstein Steven A. 
Published: February 2005

AbstractWe combined three techniques—mechanical testing, three‐dimensional imaging, and finite‐element modeling—to distinguish between the contributions of architecture and tissue modulus to mechanical function in human trabecular bone. The objectives of this study were 2‐fold. The first was to assess the accuracy of micromechanical modeling of trabecular bone using high‐contrast x‐ray images of the trabecular architecture. The second was to combine finite‐element calculations with mechanical testing to infer an average tissue modulus for the specimen. Specimens from five human L1 vertebrae were mechanically tested along the three anatomic axes. The specimens were then imaged by synchrotron x‐ray tomography, and the elastic moduli of each specimen were calculated from the tomographic image by finite‐element modeling. We found that 23‐μm tomographic images resolved sufficient structural detail such that the calculated anisotropy in the elastic modulus was within the uncertainties of the experimental measurements in all cases. The tissue modulus of each specimen was then estimated by comparing the calculated mean stiffness of the specimen, averaged over the three anatomical directions, with the experimental measurement. The absolute values of the experimental elastic constants could be fitted, again within the uncertainties of the experimental measure‐ments, by a single tissue modulus of 6.6 GPa, which was the average tissue modulus of the five specimens. These observations suggest that a combination of mechanical testing, three‐dimensional imaging, and finite‐element modeling might enable the physiological variations in tissue moduli to be determined as a function of age and gender.
Can the sagittal lumbar curvature be closely approximated by an ellipse?
Authors: Janik Tadeusz J , Harrison Donald D. , Cailliet Rene , Troyanovich Stephan J. , Harrison Deed E. 
Published: February 2005

AbstractFor the sagittal lumbar curvature, existing spinal models are based only on the anthropomorphic radiographic characteristics of one individual, or, at best, of only a few individuals. This raises questions of applicability of the modeling results to clinical situations. Because spinal coupling and loads on spinal tissues have been shown to be functions of the initial static posture, a rigorously derived neutral lumbar lordosis would be important for clinicians and spine researchers. This study presents modeling of the sagittal lumbar spine in the shape of an ellipse. Vertebral body and disc heights, derived from digitized lateral lumbar radiographs of 50 normal subjects, were used to create an ellipse along the posterior body margins from the inferior of T12 to the superior sacralbase. Additional data to create an elliptical lumbar model were determined from a least‐squares analysis of passing ellipses through the digitized posterior body points. This confirmed that an elliptical model closely fit the lumbar curvature with a least‐squares error of 1.2 mm per digitized point. The elliptical model is approximately an 85° portion of a quadrant. The semi‐major and semi‐minor axes, a and b, are parallel to the posterior body margin of T12 and parallel to the inferior body endplate of T12, respectively, with a semi‐minor to semi‐major radio of b/a = 0.39. The elliptic model has a height‐to‐' length ratio of H/L = 0.963. where height is the vertical distance from inferior T12 to superior SI and length is the arc length along George's line (along the posterior longitudinal ligament) from T12 to SI.