bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of the oim mutation by dye terminator chemistry combined with automated direct DNA sequencing
Authors: Camacho Nancy P. , Dow David , Toledano Talya R. , Buckmeyer Jennifer K. , Gertner Joseph M. , Brayton Corey F. , Raggio Cathleen L. , Root Leon , Boskey Adele L. 
Published: February 2005

AbstractThe homozygous oimloim mouse, a model of moderate‐to‐severe human osteogenesis imperfecta, contains a G‐nucleotide deletion in the Cola‐2 gene (the murine proα2(I) collagen gene) that results in accumulation of α1(I) homotrimer collagen. Although these mice have a distinctive phenotype that includes multiple fractures and deformities, genotyping is necessary to distinguish them from their wildtype (+/+) and heterozygote (oim/+) littermates. In this study, the dye primer and dye terminator chemistry methods, in combination with automated direct DNA sequencing, were compared for accuracy and ease in genotyping. A total of 82 mice from 14 litters were bred and genotyped, this resulted in 18 +/+, 35 oim/+, and 29 oim/oim mice. The dye primer and dye terminator chemistry methods worked equally well for identification of the deletion mutation and thus the genotype of all of the mice. However, the dye terminator method was found to be superior on the basis of the reduced amount of sample handling and reduced quantity of reagent required.
Bonding of cartilage matrices with cultured chondrocytes: An experimental model
Authors: Peretti Giuseppe M. , Randolph Mark A. , Caruso Enzo M. , Rossetti Francesco , Zaleske David J. 
Published: February 2005

AbstractThe capacity of isolated chondrocytes to join separate masses of cartilage matrix was investigated with composites implanted in subcutaneous pouches in nude mice. Slices of articular cartilage were harvested from lambs and were devitalized by cyclic freezing and thawing. The slices were then either co‐cultured with viable allogeneic lamb chondrocytes (experimental) or cultured without such chondrocytes (control). Composites of three slices were constructed with use of fibrin glue and were implanted in nude mice for periods ranging from 7 to 42 days. Bonding of the experimental matrices with viable chondrocytes was achieved at 28 and 42 days, as assessed by direct examination, histology, thymidine uptake, and fluorescence. No bonding occurred in the control composites without viable chondrocytes. We conclude that devitalized cartilage matrix is a scaffold to which isolated chondrocytes can attach and begin to repopulate.
Spatial and temporal expression of CD44 isoforms in the developing and growing joints of the rat limb
Authors: Noonan Kenneth J. , Reiter Rebecca S. , Kurriger Gail L. , Martin James A. , Maynard Jerry A. , Stevens Jeff W. 
Published: February 2005

AbstractHyaluronan is an integral component of proteoglycan‐rich extracellular matrices such as hyaline cartilage. Hyaluronan is commonly found in embryonic tissue and is important in the formation of hydrated matrices that allow cellular expansion and migration. Cell surface hyaluronan‐binding proteins such as CD44 are presumed to be important in the cellular interactions with hyaluronan in both of these processes. The primary aim of this study was to document the spatial and temporal expressions of CD44 isoforms during the development and growth of the diarthrodial joints of rat limbs. With use of in situ hybridization and immunohistochemistry, the CD44s isoform is selectively identified as localized to a single cell layer on opposing sides of the joint at the first appearance of joint cavitation (on the 18th day of gestation). After joint formation in the neonate, the expression of the CD44s isoform in the cells at the joint surface is lost. These findings suggest that the CD44s isoform has a role in the development of the diarthrodial joint, presumably through interaction with hyaluronan.
Fingertip loading and carpal tunnel pressure: Differences between a pinching and a pressing task
Authors: Keir Peter J. , Bach Joel M. , Rempel David M. 
Published: February 2005

AbstractCarpal tunnel syndrome may be caused by repeated or sustained elevated carpal tunnel pressure. This study examined the relationship between carpal tunnel pressure, posture, and fingertip load. In 20 healthy individuals, carpal tunnel pressure was measured with a catheter inserted into the carpal tunnel of the dominant hand and connected to a pressure transducer. With the wrist in a pressure‐neutral position, the subjects pressed on a force transducer with the index finger to levels of 0, 5, 10, and 15 N. They then pinched the transducer at the same levels of force. For both fingertip‐loading postures, the carpal tunnel pressure increased with increasing fingertip load. Carpal tunnel pressures were significantly greater (p < 0.015) for the pinching task (14.2, 29.9, 41.9, and 49.7 mm Hg [1.89, 3.99, 5.59, and 6.63 kPa] for 0, 5, 10, and 15 N force levels, respectively) than for simple finger pressing (7.8, 14.1, 20.0, and 33.8 mm Hg [1.04, 1.88, 2.67, and 4.51 kPa]). This study indicates that although the external load on the finger remained constant between the two tasks, the internal loading, as measured by carpal tunnel pressure, experienced a near 2‐fold increase by using a pinch grip. These findings should be given consideration in designing work tasks and tools because relatively low fingertip forces, especially in a pinch grip, elevate carpal tunnel pressures to levels that, if prolonged, may lead to the development or exacerbation of carpal tunnel syndrome.
Programmed removal of chondrocytes during endochondral fracture healing
Authors: Lee Francis Young‐In , Choi Yong Won , Behrens Fred F. , DeFouw David O. , Einhorn Thomas A. 
Published: February 2005

AbstractThis investigation tested the hypothesis that the removal of chondrocytes during endochondral fracture healing involves an ordered process of programmed cell death. To accomplish this, unilateral closed fractures were created in the femora of 36 Sprague‐Dawley rats. The rats were killed in groups of four on days 1, 3, 7, 14, 21, 28, 42, 49, and 56 after fracture. The femora were embedded in paraffin and tested for expression of specific markers of fragmented DNA with use of a terminal deoxyuridyl transferase‐mediated deoxyuridine triphosphatebiotin nick end labeling (TUNEL) technique. To determine the potential for trans–differentiation of chondrocytes to osteoblasts calluses were also hybridized to detect expression of osteocal in mRNA. Cell proliferation was assessed by an immunohistochemical detection method for proliferating cell nuclear antigen. A separate group of four rats was killed on day 28 to represent the later stage of the endochondral ossification, and the calluses were examined for cellular morphology with transmission electron microscopy. The results showed a coordination in both time and space of the activities of cellular proliferation and programmed cell death. Cell proliferation was most active in the earlier phases of fracture healing (days 1 through 14) although TUNEL expression was apparent in hypertrophic chondrocytes on day 14 after fracture and persisted until day 28. In the later stages of fracture healing (days 14 through 28), proliferating cell nuclear antigen was no longer synthesized in hard callus (intramembranous bone) and cell removal was the dominant activity in soft callus chondrocytes. Expression of osteocalcin mRNA was detected in osteoblasts but not in hypertrophic chondrocytes or in any other nonosteoblastic cell type. These findings support the hypothesis that the removal of chondrocytes during endochondral fracture healing is part of an ordered transition of tissue types in which the cellular mechanisms are genetically programmed to involve proliferation, maturation, and apoptotic cell death.
Bone regeneration by implantation of purified, culture‐expanded human mesenchymal stem cells
Authors: Bruder Scott P. , Kurth Andreas A. , Shea Marie , Hayes Wilson C. , Jaiswal Neelam , Kadiyala Sudha 
Published: February 2005

AbstractBone marrow contains a population of rare progenitor cells capable of differentiating into bone, cartilage, tendon, and other connective tissues. These cells, referred to as mesenchymal stem cells, can be purified and culture‐expanded from animals and humans and have been shown to regenerate functional tissue when delivered to the site of musculoskeletal defects in experimental animals. To test the ability of purified human mesenchymal stem cells to heal a clinically significant bone defect, mesenchymal stem cells isolated from normal human bone marrow were culture‐expanded, loaded onto a ceramic carrier, and implanted into critical‐sized segmental defects in the femurs of adult athymic rats. For comparison, cell‐free ceramics were implanted in the contralateral limb. The animals were elthanized at 4, 8, or 12 weeks, and healing bone defects were compared by high‐resolution radiography, immunohistochemistry, quantitative histomorphometry, and biomechanical testing. In mesenchymal stem cell‐loaded samples, radiographic and histologic evidence of new bone was apparent by 8 weeks and histomorphometry demonstrated increasing bone formation through 12 weeks. Biomechanical evaluation confirmed that femurs implanted with mesenchymal stem cell‐loaded ceramics were significantly stronger than those that received cell‐free ceramics. These studies demonstrate that human mesenchymal stem cells can regenerate bone in a clinically significant osseous defect and may therefore provide an alternative to autogenous bone grafts.
In vitrodifferentiation of chick embryo bone marrow stromal cells into cartilaginous and bone‐like tissues
Authors: Martin Ivan , Padera Robert F. , Vunjak‐Novakovic Gordana , Freed Lisa E. 
Published: February 2005

AbstractBone marrow stromal cells, progenitor cells involved in repair of bone and cartilage, can potentially provide a source for autologous skeletal tissue engineering. We investigated which factors were required to inducein vitrodifferentiation of avian bone marrow stromal cells into three‐dimensional cartilaginous and bone‐like tissues. Bone marrow stromal cells from embryonic chicks were expanded in monolayers, seeded onto biodegradable polyglycolic acid scaffolds, and cultured for 4 weeks in orbitally mixed Petri dishes. Cell‐polymer constructs developed an organized extracellular matrix containing glycosaminoglycans and collagen, whereas control bone marrow stromal cell pellet cultures were smaller and consisted predominantly of fibrous tissue. Bone marrow stromal cells expanded with fibroblast growth factor‐2 and seeded onto polymer scaffolds formed highly homogeneous three‐dimensional tissues that contained cartilage‐specific molecular markers and had biochemical compositions comparable with avian epiphyseal cartilage. When cell‐polymer constructs were cultured in the presence of beta‐glycerophosphate and dexamethasone, the extracellular matrix mineralized and bone‐specific proteins were expressed. Our work shows that cell expansion in the presence of fibroblast growth factor‐2 and cultivation on a three‐dimensional polymer scaffold allows differentiation of chick bone marrow stromal cells into three‐dimensional cartilaginous tissues. In thein vitrosystem studied, the same population could be selectively induced to regenerate either cartilaginous or bonelike tissue.
Correlation between biomechanical and structural changes during the regeneration of skeletal muscle after laceration injury
Authors: Kääriäinen Minna , Kääriäinen Janne , Järvinen Teppo L. N. , Sievänen Harri , Kalimo Hannu , Järvinen Markku 
Published: February 2005

AbstractA standardized and reliable model for muscle laceration injuries was developed. The biomechanical and morphological changes during the process of muscle repair after injury were analysed, and the reproducibility of the methods was evaluated. The soleus muscles of Sprague‐Dawley rats were completely transected and were allowed to heal for 5, 7, 10, 14, 21, 28, or 56 days, when the muscles either were pulled to failure to measure different parameters of tensile strength or were removed for morphological analysis. During the repair process, the regenerating myofibers penetrated into the connective‐tissue scar and formed new myotendinous junctions, thus restoring the functional continuity across the muscle stumps. The muscle atrophied significantly during the recovery period. Mechanical failure occurred in the scar until day 10, and thereafter it occurred within myofibers. Until day 10, the failure load, strain, and specific energy increased to as much as 46.59. and 36% of the control level, respectively: thereafter, there were only minor changes. Stress (tensile strength per cross‐sectional area) reached 86% of the control level by day 21 and further increased to as much as 96% of the control level until day 56. These results indicate that the scar becomes stronger than muscle within 14 days: thereafter, the weakest point is the atrophic muscle. The fact that the stress value was most rapidly normalized suggests that, qualitatively, the regenerated muscle had virtually regained its pretrauma strength by day 56 and that the low values of failure load, strain, and specific energy were mainly due to atrophy of the muscle. Thus, further increase in the tensile strength of the regenerated muscle‐tendon unit may require active exercise to reverse muscle atrophy.
Chondrocytes in culture produce a mechanically functional tissue
Authors: Fedewa Michelle M. , Oegema Theodore R. , Schwartz Michael H. , MacLeod Adrienne , Lewis Jack L. 
Published: February 2005

AbstractA mechanically testable tissue was grown in vitro from rabbit chondrocytes that were initially plated at high density (approximately 80.000 cells/cm2). The DNA, collagen, and proteoglycan content, as well as the tissue thickness, tensile stiffness, and synthesis rates, were measured at 4, 6, and 8 weeks. The biochemical properties were similar to those for immature cartilage, with predominantly type‐II collagen produced; this indicated that the cells retained their chondrocytic phenotype. The tissue formed a coherent mechanical layer with testable tensile stiffness as early as 4 weeks. The tensile elastic modulus reached 1.3 MPa at 8 weeks, which is in the range of values for native cartilage from the midzone. Collagen density was approximately 24 mg/ml at 8 weeks, which is about one‐half the value for native cartilage, and the collagen fibril diameters were smaller. Chondrocytes in culture responded to culture conditions and were stimulated by cytokine interleukin‐1β. When culture conditions were varied to RPMI nutrient medium with lower fetal bovine serum and higher ascorbic acid concentrations, the thickness decreased and the modulus increased significantly. Interleukin‐1β. added to the 8‐week culture for 2 weeks. caused a decrease of 60% in thickness, a decrease of 81% in proteoglycan content, and a decrease of 31% in collagen content; this is similar to the response of cartilage explants to interleukin‐1β. This cartilage analog may be useful as a model system to study structure‐function relationships in cartilage or as cartilage‐replacement tissue.
Bone morphogenetic protein‐7 in growth‐plate chondrocytes: Regulation by retinoic acid is dependent on the stage of chondrocyte maturation
Authors: Grimsrud Christopher D. , Rosier Randy N. , Puzas J Edward , Reynolds Paul R. , Reynolds Susan D. , Hicks David G. , O'Keefe Regis J. 
Published: February 2005

AbstractAlthough the bone morphogenetic proteins stimulate chondrogenesis, little is known regarding their expression and regulation in growth‐plate chondrocytes. The expression of bone morphogenetic protein‐7 was examined in chick growth‐plate chondrocyte cultures. Low basal levels of bone morphogenetic protein‐7 mRNA and protein expression were stimulated by increasing doses of all‐trans retinoic acid, a metabolite of vitamin A. The addition of 10 μM retinoic acid resulted in approximately a 6‐fold increase in bone morphogenetic protein‐7 mRNA levels. In contrast, other growth regulators, including basic fibroblast growth factor, transforming growth factor‐β. vitamin D, bone morphogenetic protein‐6, bone morphogenetic protein‐7, and parathyroid hormone‐related peptide. did not alter bone morphogenetic protein‐7 transcript levels. The increase in bone morphogenetic protein‐7 transcripts, although present at 6 hours, was maximal following a 12‐hour exposure to retinoic acid. Retinoic acid induction of Done morphogenetic protein‐7 transcript levels was dependent on protein synthesis because the induction could be blocked by cyclohexamide. In maturation‐ally distinct subpopulations of chondrocytes separated by countercurrent centrifugal elutriation, retinoic acid markedly induced bone morphogenetic protein‐7 mRNA levels in the least differentiated chondrocytes but had no effect in the most terminally differentiated hypertrophic chondrocytes. Immunohistochemical localization of bone morphogenetic protein‐7 demonstrates its expression throughout the developing and adolescent growth plate consistent with the constitutive pattern of expression seen in isolated chondrocytes. The addition of exogenous bone morphogenetic protein‐7 to chondrocyte cultures stimulated maturation in undif‐ferentiated chondrocyte populations. The data support a role for bone morphogenetic protein‐7 as an autocrine regulator of chondrocyte maturation in the growth plate. Regulation of bone morphogenetic protein‐7 by retinoic acid may be important in normal growth and development as well as in pathologic conditions of an excess or deficiency of vitamin A.
Posterior tilting of the tibial component decreases femoral rollback in posterior‐substituting knee replacement: A computer simulation study
Authors: Piazza Stephen J. , Delp Scott L. , Stulberg S. David , Stern Steven H. 
Published: February 2005

AbstractPosterior tilting of the tibial component is thought to increase the range of motion in posterior cruciate‐retaining total knee replacement, but its effect on implant motion in posterior cruciate‐substituting total knee replacement is unknown. This issue has become of interest recently because manufacturers have introduced instrumentation that produces a posteriorly tilted tibial cut for both implant types. The purpose of this study was to investigate how motion of posterior cruciate‐substituting total knee replacement is affected when the tibial component is installed with posterior tilt. Sagittal plane implant motions were predicted from prosthesis geometry with use of a computer simulation in which the femoral condyles were assumed to sit in the bottoms of the tibial condylar wells when the knee was in extension. Rollback of the femoral component was produced by a cam‐spine mechanism at higher angles of flexion. The simulations revealed that even small degrees of posterior tilt reduced rollback by limiting the interaction between the cam and spine. Tilting the component posteriorly by 5° caused the cam to contact the spine at a knee flexion angle that was 18° higher than with the untilted component. The results suggest that posterior tilting of the tibial component in posterior cruciate‐substituting knee replacement may not produce the same beneficial effects that have been reported for the tilting of tibial components in posterior cruciate‐retaining knee replacement.
Postural balance measurements for children and adolescents
Authors: Wolff Don R. , Rose Jessica , Jones V. K. , Bloch Daniel A. , Oehlert John W. , Gamble James G. 
Published: February 2005

AbstractMeasurements of standing balance were determined for 92 children and adolescents, 5–18 years old, while they stood on a force plate with eyes open or eyes closed. The measurements included center‐of‐pressure calculations for path length per second, average radial displacement, anterior‐posterior and me‐diolateral amplitudes, area per second, mean frequency of sway, Brownian random motion measure of short‐term diffusion coefficient, and long‐term scaling exponent. All balance parameters improved from youngest to oldest subjects, and the parameters improved when measured with the subjects' eyes open compared with closed. The mean values for data from three trials varied by only 5% when compared with the mean values from 10 trials. Data from this study suggest that force‐plate center‐of‐pressure data can be used to determine differences in standing balance between children and adolescents of different ages and those with movement and balance abnormalities.
Effect of intramedullary polymethylmethacrylate and autogenous cancellous bone on healing of frozen segmental allografts
Authors: Hanson Peter D. , Warner Chad , Kofroth Rachael , Osmond Christian , Bogdanske John J. , Kalscheur Vicki L. , Frassica Frank J. , Markel Mark D. 
Published: February 2005

AbstractThis study was designed to compare bone mineral density, periosteal callus production. new bone formation, bone porosity, histologic appearance, and union of mid‐diaphyseal segmental allografts of the femur stabilized with an interlocking nail technique in a canine model 4 months after the procedure. Anin vivostudy was performed to compare the effects of augmenting interlocking nail fixation with an interlocking nail alone, intramedullary polymethylmethacrylate, intramedullary polymelhylmethacrylate and autogenous cancellous bone applied to the periosteal surface of the host‐allograft junction, autogenous cancellous bone applied to the endosteal surface of the allograft, autogenous cancellous bone applied to the periosteal surface of the host‐allograft junction, and autogenous cancellous bone applied to the periosteal surface of the hostallograft junction and to the endosteal surface of the allograft. There were no differences among treatments for bone mineral density at any time interval. Callus area 4 weeks after the procedure was greater along the lateral and cranial surfaces for treatments with periosteal cancellous bone (p < 0.05). New bone within the allograft segment did not differ among treatments and was reduced compared with the host‐allograft junctions (p < 0.05). The amount and quality of bone tissue at the host‐allograft junctions were greatest with treatments of intramedullary polymethylmethacrylate and autogenous cancellous bonc applied to the periostcal surface of the host‐allograft junction and of autogenous cancellous bone applicd to the periosteal surface of the host‐allograft junction and to the endosteal surface of the allograft (p < 0.05). The rate of bone union was lower, and there was a greater gap (non‐bone tissue) remaining between host and allograft bone with treatment involving just intramedullary polymethylmethacrylate than with other treatments (p < 0.05). The results suggest that augmenting interlocking nail fixation with intramedullary polyrnethylmethacrylate by itself offers no advantage but that a combination of intramedullary polymethylmethacrylate and cancellous bone at the periosteal surface or of cancellous bone within the medullary canal and at the periosteal surface improves the quality of healing at 6 months.