bluuebunny/crossref_metadata_2025_split huggingface dataset:
Osteochondral progenitor cells in acute and chronic canine nonunions
Authors: Boyan B. D. , Caplan A. I. , Heckman J. D. , Lennon D. P. , Ehler W. , Schwartz Z. 
Published: February 2005

AbstractThis study examined the ability of cells isolated from early healing segmental defects and from tissue from chronic nonunions to support bone and cartilage formation in vivo and their response to transforming growth factor‐betal in vitro. Ostectomies (3 mm) were created in the radial diaphysis of four dogs. The dogs were splinted 3–5 days postoperatively and then allowed to bear full weight. At 7 days, tissue in the defect was removed and any periosteum was discarded; cells in the defect tissue were released by enzymatic digestion. The dogs were splinted again and allowed to bear full weight for 12 weeks. Radiographs confirmed a persistent nonunion in each dog. Defect tissue was again removed, any periosteum was discarded, and cells were isolated. Cells were also obtained from the defect tissue by nonenzymatic means with use of explant cultures. One‐half of the tissue and one‐half of any preconfluent, first‐passage cultures were shipped to Cleveland by overnight carrier. At second passage, cells were loaded into ceramic cubes and implanted into immunocompromised mice for 3 or 6 weeks. Harvested cubes were examined histologically for cartilage and bone with use of a semiquantitative scoring system. Confluent fourth‐passage cultures of 7 and 84‐day defect tissue cells were cultured with 0.03–0.88 ng/ml transforming growth factor‐betal for 24 hours, and [3H]thymidine incorporation and alkaline phosphatase specific activity were determined. Donor‐dependent differences were noted in the rate at which defect cells achieved confluence; in general, cells from 7‐day tissue divided most rapidly. Seven‐day defect cells formed less bone and at a slower rate than was seen in the ceramic cubes containing samples from day 84. Cells derived enzymatically behaved similarly to those from explant cultures. Ceramic cubes contained fibrous connective tissue, cartilage, bone, and fat, indicating that multipotent cells were present. Stimulation of [3H]thymidine incorporation in response to transforming growth factor‐betal was donor dependent and variable; only two of six separate isolates of cells exposed to it had measurable alkaline phosphatase activity (which was relatively low), and none of the cultures exhibited an increase in response to transforming growth factor‐betal for 24 hours. This indicates that mesenchymal progenitor cells are present in the healing defect tissue at 7 and 84 days and that the relative proportion of osteochondroprogenitor cells is greater at the later time. The response to transforming growth factor‐beta1 is typical of multipotent mesenchymal cells but not of committed chondrocytes or osteoblasts, indicating that these committed and differentiated cells are not present in early stages of healing and suggesting that their differentiation is inhibited in chronic nonunion.
Length changes of the hamstrings and adductors resulting from derotational osteotomies of the femur
Authors: Schmidt Deanna J. , Arnold Allison S. , Carroll Norris C. , Delp Scott L. 
Published: February 2005

AbstractDerotational osteotomies of the femur are frequently performed to treat persons with cerebral palsy who walk with excessive internal rotation of the hip. However, whether these procedures stretch or slacken the surrounding muscles appreciably is unknown. Determination of how muscle lengths are altered by derotational osteotomies is difficult because the length changes depend not only on the osteotomy site and the degree of derotation, but also on the anteversion angle of the femur and the rotational position of the hip. We have developed a three‐dimensional computer simulation of derotational osteotomies, tested by anatomical experiments, to examine how femoral anteversion, hip internal rotation, and derotation affect the lengths of the semitendinosus, semimembranosus, biceps femoris long head, adductor longus, adductor brevis, and gracilis muscles. Simulation of derotational osteotomies at the intertrochanteric, subtrochanteric, or supracondylar levels decreased the origin‐to‐insertion lengths of the hamstrings and gracilis in our model by less than 8 mm (1.8%). Hence, the lengths of the hamstrings and gracilis are not likely to be altered substantially by these procedures. The origin‐to‐insertion lengths of the adductor longus and adductor brevis decreased less than 4 mm (1.9%) with subtrochanteric correction in our model, but the length of adductor brevis increased 8 mm (6.3%) with 60° of intertrochanteric derotation. These muscles are also unlikely to be affected by derotational osteotomies, unless a large degree of intertrochanteric derotation is performed.
Sparing radiation‐induced damage to the physis by radioprotectant drugs: Laboratory analysis in a rat model
Authors: Tamurian R. M. , Damron T. A. , Spadaro J. A. 
Published: February 2005

AbstractThe radioprotectant compound amifostine (S‐2{3‐aminopropylamino}‐ethylphosphorothioc acid), administered prior to radiotherapy, has been demonstrated to provide differential protection of normal cells from the damaging effects of ionizing radiation. The aim of this pilot was to determine if amifostine could preserve the integrity of, or minimize the damage to, the physis during exposure to radiation in an animal model. Thirty weanling Sprague‐Dawley rats were randomized into five groups of six animals each. Groups 1 and 2 received a single exposure to radiation consisting of 12.5 and 17.5 Gy, respectively. Groups 3 and 4 received similar exposures of 12.5 and 17.5 Gy, respectively, but with prior administration of amifostine at 100 mg/kg. Group 5 (control) received neither radiation nor amifostine. At 6 weeks, femoral and tibial lengths were measured in treated and untreated hindlimbs and compared with the baseline lengths to calculate growth. Concordant with previous reports in the literature, the radiation doses of 12.5 and 17.5 Gy reduced net femoral growth in length by a mean of 23% (range = 12–33%, SD = 7.41) and 59% (range = 54–64%, SD = 4.45), respectively, in the irradiated limb. Amifostine reduced anticipated growth loss normally resulting from a single 12.5‐Gy radiation dose by 48.9% in the femur, 13.1% in the tibia, and 27.6% overall in the total limb (p ⩽ 0.05). Similarly, anticipated growth loss from a single 17.5‐Gy radiation dose was reduced by 30.8% in the femur, 20.3% in the tibia, and 25.7% overall in the total limb (p ⩽ 0.05). Amifostine administered prior to clinically relevant radiation exposures significantly reduced the amount of anticipated growth arrest in our animal model.
Motor functional and morphological findings following end‐to‐side neurorrhaphy in the rat model
Authors: Liu Kang , Chen Long‐En , Seaber Anthony V. , Goldner Richard V. , Urbaniak James R. 
Published: February 2005

AbstractNerve repair cannot always be achieved by the conventional end‐to‐end technique. This study evaluated the functional recovery of nerves repaired with end‐to‐side neurorrhaphy in a rat model. The right peroneal nerves of 80 female rats were transected and divided into four groups. In group A, the nerve ends were separated and remained unrepaired; in group B, the distal peroneal ends were directly sutured to the epineurium of the tibial nerves in end‐to‐side fashion; in group C, the distal ends were sutured through an epineurial window at the repair site in end‐to‐side fashion; and in group D, the nerve ends were reconnected by the traditional end‐to‐end technique. Evaluation included gait analysis by calculation of a peroneal functional index, measurement of contractile function of the extensor digitorum longus muscle, wet weight of the extensor digitorum longus, and histological examination. The findings of this study suggested the following: (a) end‐to‐side neurorrhaphy allows effective motor functional recovery, demonstrated by earlier improvement of the peroneal functional index, stronger muscle contractile function, greater muscle weight, and higher density of regenerated axons compared with unrepaired nerves; (b) removal of the epineurium of the donor nerve at the nerve coaptation site increases the effectiveness of end‐to‐side neurorrhaphy, but the epineurium appears to be a partial barrier to axonal regeneration; (c) removal of the epineurium does not affect the structure and function of the donor nerve; and (d) end‐to‐end repair achieved the best functional recovery among the four groups; therefore, end‐to‐side repair should be considered as a potential alternative only when no proximal nerve is available.
Expression of leukemia inhibitory factor by cartilage‐forming tumors of bone: An immunohistochemical study
Authors: Gouin Francois , Moreau Anne , Couillaud Séverine , Guicheux Jérôme , Passuti Norbert , Godard Anne , Heymann Dominique 
Published: February 2005

AbstractRecent studies have implicated leukemia inhibitory factor in connective‐tissue metabolism involving the remodeling of bone and the destruction of cartilage tissue. This cytokine, which has also been implicated in the proliferation of solid tumor, is expressed by osteotropic tumor cell lines. The present study investigated the presence of leukemia inhibitory factor in cartilage tissue harvested from cartilage‐forming bone tumors. Immunohistochemical study showed that it was present in all benign enchondromas (n = 8) and malignant chondrosarcomas (n = 6) but not in control tissue (n = 3). The cytokine was localized in only cytoplasmic areas of cartilage cells. The number of stained cells ranged from less than 5% in enchondroma of the hand to more than 70% in grade‐III chondrosarcoma. Moreover, high levels of leukemia inhibitory factor were found in the primary culture of tumor tissues (n = 7). These results question the significance of leukemia inhibitory factor in tumor‐associated bone resorption and the potential role of this cytokine as a prognostic marker.
Mixed‐mode fracture toughness of the cobalt‐chromium alloy/polymethlymethacrylate cement interface
Authors: Mann Kenneth A. , Bhashyam Srinivas 
Published: February 2005

AbstractMechanical debonding of the stem/cement interface has been implicated in the failure process of cemented femoral hip components. The nature of this failure process remains poorly understood due, in part, to limited understanding of how interfacial debonding occurs in response to a wide range of loading conditions. The purpose of this investigation was to determine the fracture toughness of the cobalt‐chromium alloy/polymethylmethacrylate interface under mixed‐mode loading conditions. The hypothesis was that the critical energy release rate was dependent on the phase angle of the crack tip and that the fracture response would be significantly different for a smooth compared with rough interface surface. A novel in‐plane shear test fixture was developed with use of a combination of finite element and experimental fracture‐mechanics tests. A wide range (−65–60°) of phase angles was determined with the in‐plane shear test and a clamped cantilever‐beam test. Sixty experimental tests were performed for cobalt‐chromium alloy bars with a plasma‐sprayed coating or a precoat of polymethylmethacrylate over a satin‐finished surface. For the specimens with the plasma‐sprayed coating, critical energy release rates (500–700 J/m2) were not a function of the phase angle of the crack tip. In contrast, critical energy release rates (15–80 J/m2) were found to be strongly affected by the phase angle for the specimens precoated with polymethylmethacrylate. The critical energy release rate for specimens with the plasma‐sprayed surface was significantly (p < 0.01) greater than for those precoated with polymethylmethacrylate. The critical energy release rate increased markedly with the phase angle of the crack tip for the specimens precoated with polymethylmethacrylate. The results suggest that the failure response of a stem with a plasma‐sprayed surface may be insensitive to the loading angle of the crack tip, whereas a stem precoated with polymethylmethacrylate may be more likely to debond under tensile opening loading.
Effect of molecular weight, calcium stearate, and sterilization methods on the wear of ultra high molecular weight polyethylene acetabular cups in a hip joint simulator
Authors: McKellop Harry A. , Shen Fu‐Wen , Campbell Patricia , Ota Troy 
Published: February 2005

AbstractOrthopaedic surgeons must currently choose from several types of ultra high molecular weight polyethylene acetabular cups that differ in their material properties and in the methods used for their sterilization. Information on the wear resistance of these different cups may help in the selection process. This study included two separate tests for wear run on a hip simulator to investigate the effect of molecular weight, calcium stearate, and sterilization methods on the wear resistance of ultra high molecular weight polyethylene acetabular cups. Test 1 revealed nearly identical wear rates for acetabular cups with molecular weights in two distinct ranges, as well as for cups with molecular weights in the same range but with or without calcium stearate added. In Test 2, cups that were sterilized in air with gamma irradiation exhibited lower rates of wear than those sterilized with ethylene oxide, presumably due to the crosslinking induced by the irradiation. In addition, cups that were irradiated while packed in a partial vacuum to minimize oxygen absorbed in the surface layer initially showed lower rates of wear than those irradiated in air, with the wear rates becoming similar as wear penetrated the more oxidized surface layer and the more crosslinked subsurface region. Because these tests were run a few months after the irradiation, the potential effects of long‐term oxidation of any residual free radicals in the irradiated materials could not be taken into account. After artificial aging to accelerate oxidative degradation of the materials, the wear rates could be markedly different. Analyses performed after wear indicated that the irradiated (i.e., crosslinked) cups exhibited a smaller proportion of, as well as shorter, fibrils in the wear debris and an increased crystallinity and melting temperature and that gamma irradiation in the low‐oxygen environment reduced the level of oxidation and increased the level of crosslinking in the surface region of the cups.
Increased expression of matrix metalloproteinase‐1 in osteocytes precedes bone resorption as stimulated by disuse: Evidence for autoregulation of the cell's mechanical environment?
Authors: Rubin Clinton , Sun Yan‐Qun , Hadjiargyrou Michael , McLeod Kenneth 
Published: February 2005

AbstractAn in vivo animal model of bone adaptation was used to examine a possible role for matrix metalloproteinase‐1 in the local mediation of bone remodeling: to corrode the coupling of osteocytes to the matrix in an attempt to autoregulate the cell's perception of its mechanical environment. Twelve young (12–16 months old) skeletally mature turkeys were separated into groups to be studied for stimulus periods of either 3 or 30 days. In each animal, the left ulna was functionally isolated and subjected to either disuse or 3,000 microstrain at 1 Hz for 10 minutes per day. The right ulna remained intact and served as an intra‐animal control. No significant differences in bone area were detected at 3 days; however, ulnae subjected to disuse lost 8 ± 4% (±SD) of bone area by 30 days. Over the same period, ulnae subjected to the mechanical stimulus gained 21 ± 9% of bone area. With use of in situ reverse transcription‐polymerase chain reaction, less than 2% of the osteocytes examined from the intact control ulnae stained positively for matrix metalloproteinase‐1 mRNA. An antibody raised against matrix metalloproteinase‐1 revealed no positively labeled osteocytes in the intact ulnae. This low percentage of osteocytes expressing matrix metalloproteinase‐1 mRNA was similar to that seen in ulnae subjected to the osteogenic mechanical stimuli. In contrast, ulnae subjected to either 3 or 30 days of disuse showed evidence of matrix metalloproteinase‐1 mRNA activity in a high percentage of osteocytes (89 ± 5 and 66 ± 8%, respectively; each time point significantly different from intact ulnae, as well as from each other, p < 0.05). The percentage of osteocytes labeled with the anti‐matrix metalloproteinase‐1 antibody was also highly elevated following 3 days of disuse (74 ± 17%). These data demonstrate that an early response of bone to disuse is the upregulation of matrix metalloproteinase‐1 activity in osteocytes. It is proposed that this upregulation of collagenase activity is indicative of the cell's degradation of coupling to the matrix, and it thus reflects the osteocyte's regulation of its own mechanical environment. We believe that such autoregulation of the osteocyte's physical environment will accommodate subtle changes in the bone's functional environment without the need to add or resorb bone tissue.
Effect of lengthening rate on angiogenesis during distraction osteogenesis
Authors: Li G. , Simpson A. H. R. W. , Kenwright J. , Triffitt J. T. 
Published: February 2005

AbstractThis study investigated the angiogenic response to four varying rates (0.3, 0.7, 1.3, and 2.7 mm/day) of distraction in a rabbit model of leg‐lengthening. Immunostaining was performed with use of specific antibodies to type‐IV collagen and endothelial cell antigen to examine semiquantitatively the presence of blood vessels in the developing tissues. With use of the Chalkley counting method, the greatest number of positive staining blood vessel cells was found in the central fibrous zone of the groups that underwent lengthening at 0.7 and 1.3 mm/day compared with any other zone in any group (p < 0.05, t test). There were no statistical differences in the positive labeling indices in the mineralization front and the new bone zone adjacent to the mineralization front in any of the groups. However, the decrease in the number of positive‐staining blood vessel cells in the new bone zone distant to the mineralization front compared with any other zone in any group was statistically significant. The results suggest that during distraction osteogenesis, the precursor cells of new capillaries were present in abundance within the fibrous interzone. These cells connected into the capillary network at the junction of the mineralization front and the fibrous zone. The angiogenic response was weaker in the more mature regions within the new bone zones. A slow rate of distraction (0.3 mm/day) did not maximally stimulate angiogenesis in the central fibrous zone, whereas high rates (2.7 mm/day) appeared to impair this response. In this model of distraction osteogenesis, the vascularization process in the central fibrous zone was maximally stimulated at distraction rates of 0.7 and 1.3 mm/day.
Experimental acute hematogenous osteomyelitis in mice. I. Histopathological and immunological findings
Authors: Chadha Harbinder S. , Fitzgerald Robert H. , Wiater Patrick , Sud Suda , Nasser Sam , Wooley Paul H. 
Published: February 2005

AbstractThis study investigated immunological responses to Staphylococcus aureus bone infection. Because considerable immunological information is available on the mouse, a murine model of acute hematogenous osteomyelitis was established. Osteomyelitis was created in the proximal tibia of C3H/HeJ mice by a tibial epiphyseal fracture followed by intravenous bacterial inoculation with Staphylococcus aureus (strain LS‐1). Swelling and warmth of the limb was found, and following limb exposure, abscess formation was evident in the proximal tibia. Histological examination revealed distortion primarily at the hypertrophic zone of the physis and polymorphonuclear leukocyte infiltration throughout the damaged area of the proximal tibia. Local infection was demonstrated at the fracture site, evidenced by the recovery of Staphylococcus aureus following microbiological analysis of tissue specimens. Polymerase chain reaction was utilized to detect 16S ribosomal prokaryotic nucleic acid to demonstrate that the diagnosis of osteomyelitis could be established in the absence of conventional microbiological techniques. The infected mice had an increase of circulating large leukocytes (granulocytes) and an elevation of total serum immunoglobulin. Flow cytometry revealed significant increases in splenic B lymphocytes and in lymph‐node CD4+ T lymphocytes. These results indicate that an experimental model of acute hematogenous osteomyelitis that closely resembles the pathology of the disease in humans may be consistently induced in mice. Furthermore, marked immunological changes may be observed in response to the Staphylococcus aureus bone infection.
Increased interleukin‐1β production in the synovium of glenohumeral joints with anterior instability
Authors: Gotoh Masafumi , Hamada Kazutoshi , Yamakawa Hideyuki , Nakamura Masato , Yamazaki Hitoshi , Inoue Akio , Fukuda Hiroaki 
Published: February 2005

AbstractMacroscopic synovitis of the glenohumeral joint is frequently seen during arthroscopy in patients with anterior instability. Interleukin‐1β is known to be expressed in inflamed tissue, to correlated with the magnitude of inflammation, and to affect articular cartilage in the joint. We hypothesized that chronic synovitis may occur in the glenohumeral joint in patients with anterior instability. The purpose of this study was to examine the expression of interleukin‐1β in the synovium of the glenohumeral joint with anterior instability and to discuss its clinicopathologic significance. Specimens of synovial tissue around the greater tuberosity in the subacromial synovium (as controls) and around the rotator interval in the glenohumeral synovium were obtained from 10 patients who had anterior instability without signs of subacromial impingement. Semiquantitative reverse transcriptase‐polymerase chain reaction was used to compare the levels of interleukin‐1β mRNA expression in the glenohumeral joint with those in the subacromial bursa. We also employed immunohistochemistry and in situ reverse transcriptase‐polymerase chain reaction to detect the cells producing interleukin‐1β protein and mRNA. The levels of interleukin‐1β mRNA expression were significantly higher in the glenohumeral joint than in the subacromial bursa (p < 0.01). Histology showed nonspecific inflammation in all 10 samples of glenohumeral synovium, whereas no inflammation was seen in seven of 10 samples of subacromial synovium. Immunohistochemistry identified interleukin‐1β protein in the vessels and inflammatory and synovial cells (from lining to sublining layers) in synovium of the glenohumeral joint, whereas immunoreactivity was negative in seven subacromial bursa. The remaining three synovial specimens of subacromial bursa, however, showed positive immunoreactivity that was unremarkable and confined around the vessels. In situ reverse transcriptase‐polymerase chain reaction was exclusively performed in the synovial specimens of the glenohumeral joint, which exhibited a positive reaction (in the same kinds of cells as seen with immunohistochemistry) in the lining and sublining layers and to a lesser extent in the stroma. Thus, our data confirmed the increased production of interleukin‐1β in the synovium of the glenohumeral joint in patients with anterior instability, suggesting the presence of chronic inflammation at the site. We conclude that this chronic synovitis may be partly associated with the development of dislocation arthropathy in the long term.