摘要:

AbstractGiant‐cell tumor is a primary bone tumor, of uncertain origin, with the potential capacity to metastasize. To study the role of c‐mycand c‐fosoncogene overexpression in the tumorigenesis and metastatic spread of giant‐cell tumors. 32 primary tumors were collected: of these. 19 remained disease‐free and 13 metastasized to the lung. Samples of lung metastasis from these 13 patients were also available for study. The expression of c‐mycand c‐fosmRNA was studied by reverse transcription‐polymerase chain reaction and byin situhybridization. The expression of protein was studied by Western blot analysis and by immunohistochemistry. C‐mycmRNA was overexpressed in 12 (38%) of the 32 primary tumors. Thirteen primary tumors metastasized to the lung: in nine (69%) of these. c‐mycmRNA was overexpressed. The c‐mycprotein was overexpressed in seven (54%) of the 13 tumors that metastasized to the lung. C‐foswas overexpressed in only one lung metastasis. A strong correlation between the overexpression of c‐mycand the occurrence of metastases was found: thus, c‐mycseems a powerful prognosticator in giant‐cell tumor. C‐mycwas overexpressed both in giant cells and in mononuclear cells, suggesting that both cell types are involved i

ISSN:0736-0266    

DOI:10.1002/jor.1100160102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractLittle is known about bone and cartilage tumors at the molecular level; thus, the identification of genes associated with these tumors may be useful as markers and therapeutic targets. To address this issue and to test the hypothesis that abnormal expression of one or more growth factors in the transforming growth factor‐β superfamily is associated with musculoskeletal neoplasia, degenerate primers based on the conserved sequences in these genes were made for screening tumor samples by reverse transcription‐polymerase chain reaction. First, these primers were used to obtain a comparative profile between a low‐grade chondrosarcoma and its dedifferentiated high‐grade counterpart in the same patient. This experiment identified an amplified DNA product in the high‐grade sample that was identical to osteogenic protein‐1/bone morphogenetic protein‐7. Osteogenic protein‐1 mRNA expression was 17‐fold greater in this high‐grade sample than in the low‐grade one. Osteogenic protein‐1 was highly expressed (three of three) in human osteosarcoma cell lines but was not expressed (zero of four) in normal osteoblast samples. Screening for gene expression of osteogenic protein‐1 in 57 osteosarcomas and chondrosarcomas indicated that 44% (range: 38–52%) of them were positive for osteogenic protein‐1 mRNA. Screening of breast and prostate tumors revealed a similar association with osteog

ISSN:0736-0266    

DOI:10.1002/jor.1100160103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractThis study was designed to examine whether and how glutathione and catalase increase the resistance of osteosarcoma cells to the toxicity of cisplatin. Eight osteosarcoma cell lines were exposed to varying concentrations of cisplatin. and a [3H]thymidine incorporation study then estimated their drug sensitivity. Cells were pretreated with aminotriazole and buthionine sulfoximine to depress catalase and glutathione activities and then entered into the same protocol to assess their sensitivity to cisplatin. Intracytoplasmic levels of catalase and glutathione were measured before and after the treatments. Cisplatin‐glutathione conjugates were created to examine how glutathione might depress the toxicity of cisplatin. Although the cell lines differed in the magnitude of their response to cisplatin, there was a statistical correlation between intrinsic glutathione content and cisplatin resistance. Pretreatment with aminotriazole reduced catalase activity by 84% but did not change the sensitivity to cisplatin. Depletion of glutathione activity by 70% increased the sensitivity of the cells to the cytotoxicity of cisplatin. In addition, cisplatin was detoxified following conjugation with glutathione. The increased sensitization to cisplatin toxicity caused by the depletion of glutathione and cisplatin detoxification after thein vitroreaction of glutathione to cisplatin indicated that the formation of the glutathione‐cisplatin conjugate was an important mechanism in the cellular resistance to cisplatin. These data also demonstrated that catalase activity did not contribute to resistance to cisplatin and suggested that H2O2‐induced oxidative stress did not significantly contribute to the cytotoxicity of cisplatin in osteosarcoma

ISSN:0736-0266    

DOI:10.1002/jor.1100160104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractIt would be advantageous if the mechanical properties of trabecular bone could be directly inferred from stereomorphometric parameters. For that purpose, apparent density and mean intercept length, as measures of bone mass and directionality (fabric), are commonly correlated with the elastic characteristics of bone samples, as determined in compression tests. However, complete and accurate relationships have not yet been established in this way. This may be due not only to the occurrence of artifacts in both the stereomorphometric and the mechanical assessments but also to an inherent inadequacy of mean intercept length in characterizing the full mechanical significance of bone architecture or nonhomogeneities in trabecular tissue properties not accounted for in stereomorphometry. In this study, we introduce a computer modeling approach allowing these biases to be eliminated. With use of high‐resolution three‐dimensional computer reconstructions of trabecular bone specimens for stereomorphometry and for microstructural finite element models to simulate mechanical tests, unbiased comparisons become feasible. The purpose was to investigate if accurate and complete relationships can be established in this way. Four different fabric measures were considered: mean intercept length and three volume‐based ones. Compliance matrices were calculated from fabric tensors, with use of the mathematical relationship proposed by Cowin for 29 vertebral whale‐bone specimens. These were correlated with the compliance constants determined directly from the microstructural finite element, model simulation. The nine orthotropic elastic constants of all 29 specimens were well predicted from their stereomorphometric fabric and volume fraction values, with correlation coefficients ranging from R adj2= 0.9934 to O. 9963. When individual compliance components were considered (1/Ei,. 1/Gij, or ‐vij/Ei), correlation coefficients ranged from R adj2= 0.924 to 0.9X2. All four fabric measures performed equally well. It is concluded that volume fraction and fabric measures correlate highly with the apparent elastic properties of bone samples, provided the anisotropy and nonhomgoencity in the elastic properties of the trabecular tissue itself have negligible effects on the apparent propertie Whether this is true for bone in general remains to be seen, as only a subset was analyzed here. These methods, however, can be valuable in similar assessments of

ISSN:0736-0266    

DOI:10.1002/jor.1100160105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractThe present study sought to answer two research questions. First, how distinctive, as a potential osteogenic stimulus, are short‐duration bouts of treadmill exercise relative to sedentary background activity? Second, how well does daily effective strain stimulus relate the loading history for one such exercise program, in comparison with other experimental loading programs, to bone formation?In vivocortical strains were measured in the tibiotarsus of White Leghorn chickens at a late stage of skeletal growth (14–34 weeks old) under the conditions of a previous investigation of bone formation in response to an exercise program (15 min/day, treadmill gait at 60% maximum speed while carrying 20% body mass) that included sedentary background activity. These strain data were compiled into 24‐hour loading histories of peak cyclic strain, demonstrating that strains were statistically different for exercise and background activities (p<0.0001), with both the magnitude and number of cyclic strain events being greater during exercise (generally greater than 500 microstrain, 2,500 cycles/day) than during background activity (generally less than 500 microstrain, mean: 775 cycles/day). Strains during exercise accounted for more than 97% of the daily effective strain stimulus for bone adaptation, despite the fact that exercise comprised only 1% of the daily period (15 min/day). The levels of the daily effective strain stimulus were similar to those calculated for strains engendered by artificial loading of functionally isolated avian ulnae, which either maintained bone mass or resulted in a 15% increase of cortical cross‐sectional area in both sets of studies. These results indicate that short‐duration bouts of treadmill exercise and sedentary background activity can represent distinct osteogenic stimuli for adaptive bone modeling. They also provide experimental support for the use of a daily effective strain stimulus to quantify skeletal loading histories for differing programs of physical exercise, although the relative importance of other mechanical and nonmechanical factors requires further inve

ISSN:0736-0266    

DOI:10.1002/jor.1100160106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractThe homozygousoimloimmouse, 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 +/+, 35oim/+, and 29oim/oimmice. 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

ISSN:0736-0266    

DOI:10.1002/jor.1100160107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractDespite its widespread use as graft material in orthopaedic surgical procedures, morselized cancellous bone has not yet been well characterized from the standpoint of its mechanical properties. To accommodate the noncohesive nature of this loose particulate form of bone, a triaxial compression test apparatus commonly used in engineering soil mechanics was adapted for the testing of fresh‐frozen human morselized cancellous bone specimens. Triaxial compression tests were run to 30% axial strain at five different levels of confining pressure ranging from 0.276 to 0.552 MPa. The measured axial stress versus axial strain behavior was bimodal, characterized initially by relatively stiff linear behavior, then by a rapid transition to a much more compliant (but, again, approximately linear) domain until test cessation. The apparent axial moduli of both response regions were found to be nearly linear functions of the transverse confining pressure. As typically prepared surgically, the distribution of particle size was found to have approximately 80% of the bone graft, by weight, encompassed in particles 0.42–3.2 mm in size. Triaxial tests of samples segregated by size showed that particle size had no appreciable effect on apparent material properties. The nominal Young's modulus and Poisson's ratio of morselized cancellous bone were 100 MPa and 0.2, respectiv

ISSN:0736-0266    

DOI:10.1002/jor.1100160108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractVertebral and radial anomalies are prominent features of VATERvertebral defects,anorectal anomaly,tacheoesophageal fistula with esophageal atresia, andradial dysplasia association. It has been shown that exposure of the rat fetus to adriamycin produces a spectrum of anomalies, including esophageal atresia and other features of VATER association. We aimed to document the skeletal defects found in rats exposed to teratogenic doses of adriamycinin utero. Vertebral, rib. and limb anomalies were found in 54, 54, and 35% of these examined fetuses, respectively. The range of bone lesions seen in this animal model was similar to the range of lesions seen in infants born with VATER association.

ISSN:0736-0266    

DOI:10.1002/jor.1100160109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

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 im

ISSN:0736-0266    

DOI:10.1002/jor.1100160110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY

摘要:

AbstractThis study reports the results of torsion tests, pull‐out tests, and lateral Ioading tests on osseointegrated commercially pure titanium fixtures. The tests were performedin vivoon six beagie dogs. Three fixtures, each with a diameter of 3.7mm, were installed bilaterally in the tibia of each animal. The mean maximal pull‐out load was 1.55 kN (n = 4) the mean maximal lateral transverse load was 0.21 kN (n = 2), the mean maximal lateral axial load was (0.18 kN (n = 2)) the mean breakpoint torque was 0.31 Nm (n = 3), and the mean maximal torque was 0.43 Nm (n = 3). The torsion test revealed an almost immediate plastic deformation of the interface between the implant and bone: this indicates that although the contact between the bone and the implant is close, there is no strong bond, at least not in shear. The major transfer of load from the implant to the surrounding bone tissue must therefore depend on the design of the implant. A histological evaluation with measurements of the amount of bone in contact with the fixtures was performed. By the use of the histological and mechanical data, it is possible to estimate shear stresses in bone tissue (pull‐out test) and in the interface (torque test), The mean maximal shear stress in bone tissue in the pull‐out tests was 100 MPa (n = 4); the mean shear stress in the interface was 4.3 MPa (n = 3) in the torsion tests at the breakpoint torque and was 6.0 MPa (n = 3) at the maximal torque. It was also possible to estimate the shear modulus of elasticity in the pull‐out and torque tests. The mean shear modulus in pull‐out was 119 MPa (n = 4), and the mean apparent shear modulus in torsion was 9 kPa (n = 3) for an assumed interface thickness of 100 nm and was 86 kPa (n = 3) for an assumed interface thickness

ISSN:0736-0266    

DOI:10.1002/jor.1100160111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1998

数据来源: WILEY