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Roby C Thompson

Publications and source records attributed to Roby C Thompson.

11 recordsLinked to original sources
PubMed2005

Differential gene expression in liposarcoma, lipoma, and adipose tissue.

Malignant transformation is thought to be associated with changes in the expression of a number of genes, and this alteration in gene expression is felt to be critical to the development of the malignant phenotype. Sarcomas represent a diverse group of tumors derived from cells of mesenchymal origin. Marked heterogeneity exists in the biological behavior of sarcomas, even within histologic subtypes of sarcomas. In an effort to better understand the biology of liposarcomas, gene expression in normal adipose tissue, lipomas, and liposarcomas was examined using the Affymetrix microarray technology. Differences in gene expression were quantified as the fold change in gene expression among the sample sets. Differences in gene expression among normal adipose tissue, lipomas, and liposarcomas were observed. In addition, genes expressed uniquely in liposarcoma among these and 18 other tissue sample sets were identified. Gene sets were devised that allowed the separation of liposarcomas from other samples, and most normal adipose tissue from most lipomas using the Eisen clustering software "Cluster." We conclude that differences in gene expression can be identified among different tumors derived from the adipocyte series. Such differences in gene expression may help differentiate among subtypes of sarcomas, and may also yield clues to the pathophysiology of this heterogeneous group of tumors.

Adipose Tissue↗
PubMed2004

Gene expression in giant-cell tumors.

Malignant transformation is thought to be associated with changes in the expression of a number of genes, and this alteration in gene expression is considered critical to the development of the malignant phenotype. In this study, gene expression in 8 samples of giant-cell tumor (GCT) of bone, as well as in bone at the site of osteoarthritis and in a variety of normal tissues, was determined at Gene Logic Inc (Gaithersburg, Md) with the use of Affymetrix GeneChip U_133 arrays containing approximately 40,000 genes/expressed sequence tags (ESTs). Gene-expression analysis was performed with the use of the Gene Logic GeneExpress Software System. Differences in gene expression between GCTs and bone were observed. In addition, genes expressed uniquely in GCTs among these and 519 samples from 20 other tissue types were identified. Some of the genes that were found to be overexpressed in GCTs, such as tartrate-resistant acid phosphatase and the lysosomal H + -transporting ATPase, are also expressed by osteoclasts. Osteoprotegrin ligand (OPGL) was also selectively overexpressed in GCTs. The genes found to be overexpressed in GCTs appear to reflect the genetic profile of osteoclast-lineage cells and also the genetic profile of an osteoclastogenic environment. The genes identified in this study may play a role in the pathogenesis of GCTs, confirm the likely importance of OPGL in GCT pathogenesis, and may indicate other possible targets to which antitumor therapy could be directed.

Adolescent↗
PubMed2003

Diagnostic value of open and needle biopsies in tumors of the sacrum.

STUDY DESIGN: A retrospective study with statistical analysis of 25 percutaneous needle biopsies and 54 open biopsies performed on 60 patients with tumors located in the sacrococcygeal region. OBJECTIVES: To analyze the diagnostic value of open and needle biopsies in tumors of the sacrum as well as to determine factors leading to a false or equivocal result. SUMMARY OF BACKGROUND DATA: Although percutaneous needle biopsies of the spine are valuable for thoracolumbar levels, the benefit in the sacrococcygeal region, specifically, has not previously been shown. This region is unique because of anatomic and oncologic factors. METHODS: Medical charts, imaging studies, and operative and pathologic records of patients with tumors diagnosed between 1965 and 1996 in the sacrococcygeal region reviewed were analyzed. Accuracy and effective accuracy of each procedure were then calculated. RESULTS: There were 54 primary lesions (17 benign, 37 malignant) and 6 metastatic tumors. The accuracy and effective accuracy of open biopsies was 87% and 81% but in percutaneous needle biopsies was only 44% and 12%, respectively. An unclear diagnosis resulted in the need for another biopsy in 12 of 21 primary percutaneous needle biopsies but only in 2 of 39 open biopsies (P < 0.0001, chi2). The average number of biopsies required to obtain a definitive diagnosis was significantly less if an open biopsy were performed first instead of a percutaneous needle biopsy, 1.1 versus 1.8, respectively (P = 0.0004, two-sample t test). There was a significant delay in treatment if the initial biopsy was a percutaneous needle biopsy compared with an open biopsy, mean 46 versus 4 days, respectively (P = 0.004, two-sample t test). CONCLUSION: We conclude that for sacral tumors, open biopsies have a higher effective accuracy, whereas needle biopsies are associated with a longer delay in treatment.

Adolescent↗
PubMed2003

Cell death after cartilage impact occurs around matrix cracks.

The damage from rapid high energy impacts to cartilage may contribute to the development of osteoarthritis (OA). Understanding how and when cells are damaged during and after the impact may provide insight into how these lesions progress. Mature bovine articular cartilage on the intact patella was impacted with a flat impacter to 53 MPa in 250 ms. Cell viability was determined by culturing the cartilage with nitroblue tetrazolium for 18 h or for 4 days in medium containing 5% serum before labeling (5-day sample) and compared to adjacent, non-impacted tissue as viable cells per area. There was a decrease in viable cell density only in specimens with macroscopic cracks and the loss was localized primarily near matrix cracks, which were in the upper 25% of the tissue. This was confirmed using confocal microscopy with a fluorescent live/dead assay, using 5'-chloromethylfluorescein diacetate and propidium iodide. Cell viability in the impacted regions distant from visible cracks was no different than the non-impacted control. At 5 days, viable cell density decreased in the surface layer in both the control and impacted tissue, but there was no additional impact-related change. In summary, cell death after the impaction of cartilage on bone occurred around impact induced cracks, but not in impacted areas without cracks. If true in vivo, early stabilization of the damaged area may prevent late sequelae that lead to OA.

Animals↗
PubMed2002

Results of treatment for metastatic osteosarcoma with neoadjuvant chemotherapy and surgery.

The purpose of the current study was to define the survival outcome variables for the 85 patients with Stage IIB osteosarcoma treated with neoadjuvant chemotherapy at the authors' institution from 1982 to 1997. A minimum 4-year followup or death was a requisite for inclusion. Forty-three patients were relapse-free survivors and 14 had no evidence of disease at followup for an overall survival of 67%. Twenty-nine patients had thoracotomy and nine have no evidence of disease with a minimum 4-year followup from last thoracotomy. The mean time to metastasis after diagnosis for patients presenting with Stage IIB disease was 12.8 months. There was no difference in the survival for any of the three chemotherapy protocols, used during the 15 years included in this analysis. There was a significant relation between length of time to relapse and survival. For each additional year without relapse, there is an 18% increase in chance of survival. In patients who were treated with thoracotomy, the number of metastatic nodules was a significant predictor of survival; specifically, each nodule increased the risk of death by 43%. A favorable outcome in this cohort of patients is related to the length of time between initiation of therapy and diagnosis of metastasis, and the number of metastatic foci.

Adolescent↗
PubMed2002

Pathologic fracture in osteosarcoma : prognostic importance and treatment implications.

BACKGROUND: The presence of a pathologic fracture in an osteosarcoma has been considered a poor prognostic factor and an indication for immediate amputation. The purpose of the present study was to determine, in the current era of neoadjuvant chemotherapy, whether a pathologic fracture in an osteosarcoma has prognostic importance and whether limb salvage can be safely performed in such patients without compromising clinical outcome. METHODS: In a cooperative effort of the Musculoskeletal Tumor Society, members from eight institutions provided retrospective data on fifty-two patients with osteosarcoma who had a pathologic fracture and on fifty-five patients with osteosarcoma who had not had a pathologic fracture and had been followed for at least two years or until disease recurrence, metastasis, or death. The two groups were matched for patient age and tumor location. Outcomes examined were survival and local recurrence. A subgroup analysis was performed to assess differences in outcome within the group with the pathologic fracture. RESULTS: The five-year estimated survival rates were 55% for the group with a pathologic fracture and 77% for the group without a fracture (p = 0.02). The rate of survival without a local recurrence at five years was 75% for the group with a fracture and 96% for the group without a fracture (p = 0.007). In the group with a fracture, seven (23%) of the thirty patients managed with limb salvage and four (18%) of the twenty-two managed with an amputation had a local recurrence (p = 0.75). Eleven (37%) of the thirty patients with a fracture who were managed with limb salvage and ten (45%) of the twenty-two patients with a fracture who were managed with an amputation died of the disease (p = 0.50). Five patients underwent open reduction and internal fixation followed by limb-salvage surgery. Two of them had a local recurrence and died at an average of eight months postoperatively. The remaining three patients were alive at an average of 6.1 years postoperatively. Local disease control and the survival of these patients were not significantly different from those for the thirty-three patients who were treated with nonoperative immobilization of the fracture followed by limb-salvage surgery. CONCLUSIONS: Patients with osteosarcoma who present with a pathologic fracture or sustain one during preoperative chemotherapy have an increased risk of local recurrence and a decreased rate of survival compared with patients who have not sustained a pathologic fracture. The performance of a limb-salvage procedure in carefully selected patients with a pathologic fracture does not significantly increase the risk of local recurrence or death. Factors predictive of improved outcome, such as the response to chemotherapy and union of the fracture, should be taken into account when limb salvage is being considered.

Adolescent↗
PubMed2002

Proximal femoral replacement.

Reconstruction of the proximal femur after extensive bone loss is clinically challenging. Options for reconstruction depend on the classification and extent of the proximal femoral defect. Although reconstitution of the native proximal femoral bone stock are the traditional goals of most revision techniques for the proximal femur, these techniques lose their effectiveness after numerous revisions due to the severe loss of a sufficient amount of structural bone needed to reconstruct the femur and abductor attachment. Consequently, the proximal femoral bone becomes fragile with extensive bone loss despite bone grafting. Techniques that use allograft-prosthetic composite and femoral megaprosthesis can successfully restore a patient's ambulatory ability despite the absence of significant portions of the proximal femur.

Bone Transplantation↗