bluuebunny/crossref_metadata_2025_split huggingface dataset:
Type‐I collagen mutation compromises the post‐yield behavior of Mov13 long bone
Authors: Jepsen Karl J. , Goldstein Steven A. , Kuhn Janet L. , Schaffler Mitchell B. , Bonadio Jeffrey 
Published: February 2005

AbstractDespite recent advances in our understanding of the molecular basis of skeletal fragility, little is known about how these molecular alterations lead to whole bone brittleness. In the current study, we investigated the relationship between a type‐I collagen mutation and post‐yield behavior of whole bone in Mov13 transgenic mice by considering tissue‐level organizational issues known to be important for normal bone fracture. Mechanical assays revealed that the post‐yield deflection of Mov13 femurs was reduced by 61% relative to littermate controls. Fractographic images revealed that lamellar interfaces, which were important for dissipating energy during the failure process of control femurs, were not effective in Mov13 mice. Further investigation revealed that a 22% reduction in bone collagen content, a 2‐fold increase in tissue porosity, and significant alterations in collagen organization interfered with normal energy dissipation mechanisms of Mov13 microstructure. Collectively, the results provided the first evidence that the reduced ductility associated with a type‐I collagen mutation was mediated by alterations in intermediate structures that normally contribute to the post‐yield behavior of cortical bone. The results suggest that, to better understand the pathogenesis of skeletal fragility, it is important to consider the effects of molecular alterations on higher‐level structures, particularly those structures that contribute to the failure mechanisms in normal bone.
Adenovirus‐mediated gene transfer into tendon and tendon sheath
Authors: Lou Jueren , Manske Paul R. , Aoki Mitsuhiro , Joyce Michael E. 
Published: February 2005

AbstractIn this study, we successfully transferred the Escherichia coli β‐galactosidase gene, LacZ, into the chicken tendon and tendon sheath by a recombinant adenovirus. The recombinant adenovirus Adv‐βgal that carried the E. coli LacZ gene was constructed by homologous recombination in 293 cells (human transformed embryonic kidney) between the expressing vector and the ClaI large fragment of adenovirus 5 genome. Each chicken received a 10 μl injection, containing 105 plaque‐forming units of recombinant virus Adv‐βgal, into the tendon sheath of the long toe. Samples of tendon and tendon sheath were harvested at 3, 30, and 75 days after the injection. The LacZ gene transfer was detected for its coding product β‐galactosidase by staining with X‐gal solution. The results showed that all tendon and tendon sheath samples from the three harvest times stained positive (blue). The tendon sheath samples were more extensively stained; staining of the tendon was limited to the epitenon layer. These data suggest that a functional exogenous gene can potentially be transferred into the tendon and tendon sheath by similar techniques; such techniques may be used to improve healing and reduce adhesion formation.
Age trends in remodeling of the femoral midshaft differ between the sexes
Authors: Feik S. A. , Thomas C. D. L. , Clement J. G. 
Published: February 2005

AbstractCross‐sectional area properties of the femoral midshaft from 203 individuals of known height and weight, 1–97 years of age, from a modern Australian population were quantified using automatic video image analysis. The aim of this study, taking height and weight into account, was to determine whether (a) age trends in remodeling differ between the sexes, (b) men are better able to compensate for bone loss with age, and (c) this protective mechanism is carried through into old age. Our findings indicated that during adulthood there are distinct gender differences in femoral remodeling. From around the third to the seventh decade, men showed a fairly uniform increase in subperiosteal area, polar moment of inertia, and medullary area. Women displayed two distinct phases during this period: relative stability until around the menopause and then a marked increase in all of the above variables. In old age, gender differences diminished, both sexes showing reduced periosteal apposition and increased endosteal resorption. The resultant decline in cortical area of approximately 4% in men and 15% in women from the third to the eighth decade was significant only in women. For a given height, men had larger, stiffer femoral shafts with a greater cortical width and area and maintained this advantage into old age. Diaphyseal bone was not immune from age‐related changes affecting other skeletal sites; however, due to compensatory remodeling, which was particularly evident in men, this was not reflected in increased fracture rates.
Local expression of human growth hormone in bone results in impaired mechanical integrity in the skeletal tissue of transgenic mice
Authors: Tseng Kuo‐Fung , Bonadio Jeffrey F. , Stewart Timothy A. , Baker Andrew R. , Goldstein Steven A. 
Published: February 2005

AbstractThe effect of local production of human growth hormone on murine cortical bone was investigated using a transgenic mouse model. Femora and humeri from human growth hormone transgenic mice and littermate control mice were obtained, and the geometrical, biomechanical, compositional, and histomorphometric properties of all specimens were determined. The goals were to investigate the effects of local expression of human growth hormone on skeletal integrity, including the functional geometry of long bone and its related structural and mechanical behavior, as well as tissue composition and integrity. As expected, local production of human growth hormone by osteoblasts indeed resulted in longer femora with significantly greater mid‐diaphyseal cross‐sectional geometry in the transgenic mice (16% increase in cross‐sectional area and 29% increase in bending moments of inertia). However, the significant increase in geometry was not associated with a proportional increase in bending stiffness and other structural properties, which suggested that the mechanical properties of the cortical bone tissue may have been inferior. Microspecimen bending tests verified this prediction, given that transgenic cortical bone tissue had significantly lower apparent elastic modulus and ultimate strength (52 and 68%, respectively, of control values). These defects in the whole bone structural and tissue mechanical properties of transgenic specimens were associated with a smaller fraction of ash, larger fractions of woven bone and cartilage islands, and greater porosity in the mid‐diaphyseal cortices. These results suggest that local production of human growth hormone by osteoblasts is indeed anabolic for bone, but at the expense of bone tissue integrity.
Endothelin induces vasoconstriction in the bone vasculature in vitro: An effect mediated by a single receptor population
Authors: Coessens B. C. , Miller V. M. , Wood M. B. 
Published: February 2005

AbstractThe aim of this study was to define the types of endothelin receptors present in the canine tibial vasculature. Endothelin receptor agonists and antagonists were used in two different models: isolated nutrient tibial arteries in organ bath and in vitro‐perfused canine tibial bones. In isolated nutrient tibial arteries, endothelin‐1 caused concentration‐dependent contractions of rings with and without endothelium. BQ‐123, a selective endothelin‐A antagonist, induced a significant rightward shift of endothelin‐1 concentration‐response curves. No contractions were observed with sarafotoxin S6c, a selective endothelin‐B agonist. The responses of endothelin‐1 were not affected by the presence of NG‐monomethyl‐L‐arginine acetate plus indomethacin or by removal of the endothelium. In perfused tibial bones, endothelin‐1 was more potent than endothelin‐3 in causing concentration‐dependent contractions. Neither endothelin‐1, endothelin‐3, nor sarafotoxin S6c caused relaxations. Neither the inhibition of nitric oxide nor the inhibition of prostaglandins significantly altered contractions to endothelin‐1. These concordant data indicate that endothelin is a vasoconstrictor in the bone vasculature, an effect that appears to be mediated only through endothelin‐A receptors.
Coloured microsphere assessment of blood flow to knee ligaments in adult rabbits: Effects of injury
Authors: Bray R. C. , Butterwick D. J. , Doschak M. R. , Tyberg J. V. 
Published: February 2005

AbstractColoured microspheres were used to determine standardized blood flow in an established model of medial collateral ligament injury in the adult rabbit knee. Resting blood flow in the ligament was ascertained to be on the order of 0.68 ± 0.08 ml/min/100 g (mean ± SEM) in normal rabbit knees, although errors in flow estimates of this magnitude may be quite high. In healing medial collateral ligament, however, flow had increased markedly 3 weeks after injury (21.45 ± 5.48 ml/min/100 g). Flows in sham‐operated control medial collateral ligaments were not significantly increased compared with those in control normal ligaments. Six weeks after injury, blood flow in the ligament remained elevated (16.90 ± 3.20 ml/min/100 g) and was similarly elevated in other neighbouring joint tissues (i.e., ipsilateral synovial fat pad). The increase in flow to ipsilateral noninjured articular tissues did not persist beyond 6 weeks, but flow in the healing medial collateral ligament scar tended to remain elevated after 17 weeks (4.20 ± 1.79 ml/min/100 g), although this did not achieve statistical significance. We conclude from these data that it is possible to measure the increase in blood flow in injured and healing articular tissues using the coloured microspheres technique and that ligament injury is a potent stimulus for increasing blood flow. Coloured microsphere measurements of blood flow to joint connective tissues may offer a valuable approach to future investigations of joint injury and arthritis.
Wrist joint motion simulator
Authors: Werner Frederick W. , Palmer Andrew K. , Somerset James H. , Tong Jason J. , Gillison Douglas B. , Fortino Maria D. , Short Walter H. 
Published: February 2005

AbstractA computer controlled wrist joint motion simulator has been developed that actively moves forearms from cadavers through cyclic planar flexion‐extension motions, planar radial‐ulnar deviation motions, and combined motions such as circumduction. Hybrid position‐force feedback control algorithms are used to determine the wrist flexor and extensor tendon forces necessary to achieve the desired motions. The simulator was used in a series of 12 fresh cadaver forearms to produce both flexion‐extension and radial‐ulnar deviation motions and was found to cause repeatable, physiological movements. In these experiments, the extensor tendon forces were greater than those of the flexors, typically by a factor of two.
Relative effects of wound healing and mechanical stimulus on early bone response to porous‐coated implants
Authors: Hollister Scott J. , Guldberg Robert E. , Kuelske Cheryl L. , Caldwell Nancy J. , Richards Mark , Goldstein Steven A. 
Published: February 2005

AbstractWe hypothesized that early bone adaptation to well fixed porous‐coated implants is influenced more by wound healing than by mechanical loading. To test this hypothesis, two groups of dogs with identical, hydraulically controlled porous‐coated implants interference fit within distal femoral trabecular bone were used. One group had no load; the other had 35 N of load applied to the implants. At 5 weeks after surgery, the resulting adaptation of bone around the implants was quantified on a cellular basis by cytochemical analysis of type‐I procollagen synthesis and on a structural basis using three‐dimensional micro‐computed tomography imaging. The percentage of trabecular surfaces covered by osteoblasts expressing type‐I procollagen was significantly increased in bone surrounding the implant in both groups compared with contralateral control bone tissue. There was no difference between the groups with no load or 35 N of load. In addition, measures of trabecular bone structure did not differ significantly between the load and no‐load groups. Taken together, these results suggest that wound healing plays a much greater role in the early response of bone to well fixed porous‐coated implants than does mechanical stimulus.
Influence of bacterial strains on bone infection
Authors: Corder José , Munuera Luis , Folgueira María Dolores 
Published: February 2005

AbstractExperiments were performed on 120 rabbits to compare the probability of infection after bone surgery without an implant, with polymethylmethacrylate, and with bone autografts. Staphylococcus aureus phage type 94/96. Isolated from a human osteomyelitis, was instilled into the intramedullar cavity after reaming of the femoral canal and before insertion of the implant. The different 50% infective doses were determined for each of the groups for comparative purposes. The bacterial concentrations required to produce infection in femora without an implant were two times less than those necessary in femora implanted with polymethylmethacrylate. The bone graft required bacterial concentrations nine times less than those necessary to infect femora containing polymethylmethacrylate and four times less than those required to infect femora without an implant. The results presented here confirm that the susceptibility to infection in orthopaedic surgery is not only material dependent but also bacteria dependent.
Influence of dosage and timing of application of platelet‐derived growth factor on early healing of the rat medial collateral ligament
Authors: Batten M. L. , Hansen J. C. , Dahners L. E. 
Published: February 2005

AbstractIn previous studies, platelet‐derived growth factor has demonstrated beneficial in vivo effects on wound healing. We report the results of two studies of platelet‐derived growth factor in the rat medial collateral ligament injury model. Experimental injury sites were implanted with platelet‐derived growth factor, whereas contralateral controls received only collagen. Twelve days postoperatively, the femur‐medial collateral ligament‐tibia complex was tested mechanically. Our first study found a marked drop in the effectiveness of platelet‐derived growth factor when it was administered more than 24 hours after injury. Dose‐response testing showed maximum increases in strength (90% ) with 5.0 μg of platelet‐derived growth factor, but the 1.0 μg group showed similar strength increases, indicating a probable plateau effect in the response. These results indicate that platelet‐derived growth factor has promise for healing ligaments but that it must be administered in appropriate doses soon after injury.
Cement viscosity affects the bone‐cement interface in total hip arthroplasty
Authors: Stone James J‐S. , Rand James A. , Chiu Eric K. , Grabowski John J. , An Kai‐Nan 
Published: February 2005

AbstractQuantitative information regarding the interface strength and degree of cement penetration associated with cement viscosity during total hip arthroplasty is limited. The aim of the present study was to determine the effect of the viscosity of bone cement at the time of implantation on the mechanical integrity of total hip arthroplasty. Cement that was injected at an early, less viscous stage produced greater failure strength in a push‐out test than its more viscous counterpart.
Osteoblast adhesion to orthopaedic implant alloys: Effects of cell adhesion molecules and diamond‐like carbon coating
Authors: Kornu Roger , Smith R. Lane , Maloney William J. , Kelly Michael A. 
Published: February 2005

AbstractIn total joint arthroplasty, long‐term outcomes depend in part on the biocompatibility of implant alloys. This study analyzed effects of surface finish and diamond‐like carbon coating on osteoblast cell adhesion to polished titanium‐aluminum‐vanadium and polished or grit‐blasted cobalt‐chromium‐molybdenum alloys. Osteoblast binding was tested in the presence and absence of the cell adhesion proteins fibronectin, laminin, fibrinogen, and vitronectin and was quantified by measurement of DNA content. Although adherence occurred in serum‐free medium, maximal osteoblast binding required serum and was similar for titanium and cobalt alloys at 2 and 12 hours. With the grit‐blasted cobalt alloy, cell binding was reduced 48% (p < 0.05) by 24 hours. Coating the alloys with diamond‐like carbon did not alter osteoblast adhesion, whereas fibronectin pretreatment increased cell binding 2.6‐fold (p < 0.05). In contrast, fibrinogen, vitronectin, and laminin did not enhance cell adhesion. These results support the hypothesis that cell adhesion proteins can modify cell binding to orthopaedic alloys. Although osteoblast binding was not affected by the presence of diamond‐like carbon, this coating substance may influence other longer term processes, such as bone formation, and deserves further study.
Differential growth by growth plates as a function of multiple parameters of chondrocytic kinetics
Authors: Wilsman Norman J. , Leiferman Ellen M. , Fry Michael , Farnum Cornelia E. , Barreto C. 
Published: February 2005

AbstractDifferential elongation of growth plates is the process by which growth‐plate chondrocytes translate the same sequence of gene regulation into the appropriate timing pattern for a given rate of elongation. While some of the parameters associated with differential growth are known, the purpose of this study was to test the hypothesis that eight independent variables are involved. We tested this hypothesis by considering four different growth plates in 28‐day‐old Long‐Evans rats. Temporal parameters were provided by means of oxytetracycline and bromodeoxyuridine labeling techniques. Stereological parameters were measured with standard techniques. For all four growth plates, the calculated number of new chondrocytes produced per day approximated the number of chondrocytes lost per day at the chondro‐osseous junction. This suggests that the proposed equations and associated variables represent a comprehensive set of variables defining differential growth. In absolute numbers, the proximal tibial growth plate produced about four times as many chondrocytes per day as the proximal radial growth plate (16,400 compared with 3,700). In the proximal tibia, 9% of growth is contributed by cellular division; 32%, by matrix synthesis throughout the growth plate: and 59%, by chondrocytic enlargement during hypertrophy. In the more slowly elongating growth plates, the relative contribution to elongation from cellular enlargement decreases from 59 to 44%, with a relative increase in contribution from matrix synthesis ranging from 32% in the proximal tibia to 49% in the proximal radius. This study suggests that differential growth is best depicted as a complex interplay among cellular division, matrix synthesis, and cellular enlargement during hypertrophy. Differential growth is best explained by considering a set of eight independent variables, seven of which vary from growth plate to growth plate. Thus, this study confirms the importance of cellular hypertrophy during elongation and adds to our understanding of the importance of locally mediated regulatory systems controlling growth‐plate activity.
Osteocyte density and histomorphometric parameters in cancellous bone of the proximal femur in five mammalian species
Authors: Mullender M. G. , Huiskes R. , Versleyen H. , Buma P. 
Published: February 2005

AbstractThe species‐specific relationships between trabecular morphology and osteocyte density were investigated in the femoral heads of 30 adult animals of five mammalian species (rat, rabbit, Rhesus monkey, pig, and cow). Our hypothesis is that osteocytes are mechanosensory cells and are involved in the regulation of bone remodeling. According to the predictions from a simulation model, this hypothesis implies that the influencing distance of osteocytes, together with the magnitude of the mechanical loads, determines the thickness of trabeculae and that the number of osteocytes primarily affects the rate of bone remodeling. The number of osteocytes per bone volume ranged from 93,200 mm−3in rat to 31,900 mm−3in bovine cancellous bone. Osteocyte density was inversely related to the size of the species. Since basal metabolic output is related to body mass, we speculate that osteocyte density may be related to metabolic rates. Trabecular thickness was larger in the cow than in the other species, but the range of variation between species was relatively small. This agrees with the hypothesis that trabecular thickness is limited by the domain that can be regulated by an osteocyte and that this domain is of similar size regardless of the species. Only in the rat was trabecular thickness considerably smaller than in the other species. This is probably due to the presence of the cartilaginous growth plate in the femoral head of the rat. The relationships with species are different for osteocyte density than for morphometric parameters. Hence, our data support our hypothesis that osteocyte density is not directly associated with the macroscopic trabecular architecture.
Effects of medial and lateral displacement calcaneal osteotomies on tibiotalar joint contact stresses
Authors: Steffensmeier S. J. , Berbaum K. S. , Brown T. D. 
Published: February 2005

AbstractTranslational calcaneal osteotomies are used clinically to realign the mechanical axis of the lower limb. In this study, the effects of medial and lateral displacements of the posteroinferior fragment on tibiotalar joint contact mechanics were assessed using pressure‐sensitive film. Eight osteotomized fresh‐frozen cadaver specimens were loaded in each of three testing positions: neutral position (no shift), 1 cm of lateral displacement of the inferior fragment with respect to the superior fragment, and 1 cm of medial displacement of the inferior fragment. For an applied load of 1.330 N, two times body weight, a 1 cm lateral displacement shifted the center of pressure an average of 1.06 mm laterally, whereas a 1 cm medial displacement shifted the center of pressure an average of 1.58 mm medially. While global contact parameters (contact area, spatial mean contact stress, and peak local contact stress) were not appreciably altered by osteotomy, regional contact parameters changed in a reproducible and statistically significant manner. Among four nominally equal‐sized, parasagittally bounded cartilage zones, lateral displacements consistently unloaded the most medial zone and increased loading of the most lateral zone; medial calcaneal displacements had the converse effect. These cadaver results suggest that translational calcaneal osteotomies may be used clinically to partially offload focal areas of cartilage along the medial and lateral borders of the tibiotalar joint.