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Biomedical subjects

Michael A Simon

Publications and source records attributed to Michael A Simon.

30 records · Page 2Linked to original sources
PubMed2003

A comparison study of staging systems for bone sarcomas.

A retrospective study of 250 patients treated at one institution was done to evaluate the prognostic significance of the new American Joint Committee on Cancer staging system compared with the Musculoskeletal Tumor Society staging system for patients with sarcomas of bone. Regarding the Musculoskeletal Tumor Society system, there were significant differences in survival among patients with Stage I, Stage II, and Stage III disease. There were no significant differences between patients with Stages I-A and I-B disease, nor between patients with Stages II-A and II-B disease. Similarly, regarding the new American Joint Committee on Cancer staging system, there were significant differences among patients with Stage I, Stage II, and Stage IV disease. No significant differences were seen between patients with Stages I-A and I-B disease, between patients with Stages II-A and II-B disease, nor between patients with Stages IV-A and IV-B disease. A significant advantage in the ability to predict prognosis for one staging system over the other staging system was not shown with the relatively small number of patients in this study.

Ameloblastoma↗
PubMed2003

Oncologic outcomes of primary lymphoma of bone in adults.

A retrospective analysis of adult patients who had lymphomatous involvement of bone was done to evaluate the prognostic factors and the oncologic outcome. Between 1984 and 1994, 28 patients (nine women and 19 men) were diagnosed with lymphoma of bone. The median age was 45 years (range, 23-76 years). The median followup was 40.3 months (range, 0.5 months-15.8 years). Eighteen patients (64%) were classified as having Stage IE disease, two patients (36%) were classified as having stage II disease, and eight patients were classified as having Stage IV disease. Twenty-one of the lesions were classified as diffuse large B cell with multilobulated nuclei. Two patients had local recurrence. Three patients had osteonecrosis develop at the site of their radiation therapy. The 5-year Kaplan-Meier survival estimate was 57.8% (95% confidence interval range, 40-33 82.8). Statistically improved survival was seen in patients younger than 40 years and those patients with diffuse large B cell with multilobulated nuclei. Patients with primary lymphoma of bone did not have a statistically improved survival compared with patients with systemic disease. The results of the current study suggest that age at diagnosis and histologic subtypes are important prognostic factors; however, the diagnosis of primary lymphoma of bone does not confer improved prognosis.

Adult↗
PubMed2003

Epithelioid hemangiomas of bone: spontaneous clinical and radiographic remission.

A case of pathologic multifocal epithelioid hemangioma which occurred in the perigestational period is reported. This is the only reported case in which an epithelioid hemangioma, without treatment, went into radiographic and clinical remission. This case may suggest an alternative treatment for epithelioid hemangioma. Rather than radiation therapy or amputation, close observation of this benign neoplasm may be indicated.

Adult↗
PubMed2002

Cytoplasmic and/or nuclear accumulation of the beta-catenin protein is a frequent event in human osteosarcoma.

The molecular events that precede the development of osteosarcoma, the most common primary malignancy of bone, are unclear, and concurrent molecular and genetic alterations associated with its pathogenesis have yet to be identified. Recent studies suggest that activation of beta-catenin signaling may play an important role in human tumorigenesis. To investigate the potential role of beta-catenin deregulation in human osteosarcoma, we analyzed a panel of 47 osteosarcoma samples for beta-catenin accumulation using immunohistochemistry. Potential activating mutations were investigated by sequencing exon 3 of the beta-catenin gene in genomic DNA isolated from tumor samples. Our findings revealed cytoplasmic and/or nuclear accumulation of beta-catenin in 33 of 47 samples (70.2%); however, mutation analysis failed to detect any genetic alterations within exon 3, suggesting that other regulatory mechanisms may play an important role in activating beta-catenin signaling in osteosarcoma. In our survival analysis, beta-catenin deregulation conferred a hazard ratio of 1.05, indicating that beta-catenin accumulation does not appear to be of prognostic value for osteosarcoma patients. When analyzed against other clinicopathologic parameters, beta-catenin accumulation correlated only with younger age at presentation (26.4 vs. 39.8 years). Nevertheless, our results demonstrate that the deregulation of beta-catenin signaling is a common occurrence in osteosarcoma that is implicated in the pathogenesis of osteosarcoma.

Adult↗
PubMed2002

Regulation of Frizzled by fat-like cadherins during planar polarity signaling in the Drosophila compound eye.

Planar polarity is evident in the coordinated orientation of ommatidia in the Drosophila eye. This process requires that the R3 photoreceptor precursor of each ommatidium have a higher level of Frizzled signaling than its neighboring R4 precursor. We show that two cadherin superfamily members, Fat and Dachsous, and the transmembrane/secreted protein Four-jointed play important roles in this process. Our data support a model in which the bias of Frizzled signaling between the R3/R4 precursors results from higher Fat function in the precursor cell closer to the equator, which becomes R3. We also provide evidence that positional information regulating Fat action is provided by graded expression of Dachsous across the eye and the action of Four-jointed, which is expressed in an opposing expression gradient and appears to modulate Dachsous function.

Animals↗
PubMed2002

MASK, a large ankyrin repeat and KH domain-containing protein involved in Drosophila receptor tyrosine kinase signaling.

The receptor tyrosine kinases Sevenless (SEV) and the Epidermal growth factor receptor (EGFR) are required for the proper development of the Drosophila eye. The protein tyrosine phosphatase Corkscrew (CSW) is a common component of many RTK signaling pathways, and is required for signaling downstream of SEV and EGFR. In order to identify additional components of these signaling pathways, mutations that enhanced the phenotype of a dominant negative form of Corkscrew were isolated. This genetic screen identified the novel signaling molecule MASK, a large protein that contains two blocks of ankyrin repeats as well as a KH domain. MASK genetically interacts with known components of these RTK signaling pathways. In the developing eye imaginal disc, loss of MASK function generates phenotypes similar to those generated by loss of other components of the SEV and EGFR pathways. These phenotypes include compromised photoreceptor differentiation, cell survival and proliferation. Although MASK is localized predominantly in the cellular cytoplasm, it is not absolutely required for MAPK activation or nuclear translocation. Based on our results, we propose that MASK is a novel mediator of RTK signaling, and may act either downstream of MAPK or transduce signaling through a parallel branch of the RTK pathway.

Amino Acid Sequence↗
PubMed2002

Nuclear receptor agonists as potential differentiation therapy agents for human osteosarcoma.

PURPOSE: This study was designed to investigate whether nuclear receptor agonists can be used as potential differentiation therapy agents for human osteosarcoma. EXPERIMENTAL DESIGN: Four osteosarcoma cell lines (143B, MNNG/HOS, MG-63, and TE-85) were treated with proliferator-activated receptor (PPAR)gamma agonists, troglitazone and ciglitazone, and a retinoid X receptor (RXR) ligand, 9-cis retinoic acid. The proliferation and induction of apoptosis in the treated cells were assessed, as was the induction of alkaline phosphatase, a differentiation marker of osteoblasts. RESULTS: The expression of PPARgamma was readily detected in all tested osteosarcoma lines. On treatment with the PPARgamma and RXR ligands, all four osteosarcoma lines exhibited a significantly reduced proliferation rate and cell viability. Among the four lines, 143B and MNNG/HOS were shown to be more sensitive to ligand-induced apoptosis, as demonstrated by the Crystal Violet and Hoechst staining assays. Of the three tested ligands, troglitazone was shown to be the most effective in inducing cell death, followed by 9-cis retinoic acid. Moreover, a strong synergistic effect on the induction of cell death was observed when both troglitazone and 9-cis retinoic acid or ciglitazone and 9-cis retinoic acid were administered to osteosarcoma cells. Troglitazone was shown to effectively induce alkaline phosphatase activity, a well-characterized hallmark for osteoblastic differentiation. CONCLUSIONS: Our findings suggest that PPARgamma and/or RXR ligands may be used as efficacious adjuvant therapeutic agents for primary osteosarcoma, as well as potential chemopreventive agents for preventing the recurrence and metastasis of osteosarcoma after the surgical removal of the primary tumors.

Alitretinoin↗
PubMedDate not supplied

Benign fibrous histiocytoma: a rare finding on bone scan staging for prostate adenocarcinoma.

Benign fibrous histiocytoma is a rare bone tumor that usually presents with localized pain and/or a pathological fracture. We report on a patient with adenocarcinoma of the prostate who had a radionuclide bone scan for staging, which was suspicious for metastatic disease. Histologic examination of left eleventh rib revealed a Benign Fibrous Histiocytoma (BFH). To our knowledge, this is the first BFH found solely on bone scan.

Adenocarcinoma↗
PubMedDate not supplied

Intraoperative cell salvage during radical prostatectomy: a safe technique for Jehovah's Witnesses.

Radical retropubic prostatectomy (RRP) is an operation historically associated with the potential for significant blood loss. Patients who refuse a blood transfusion, such as Jehovah's witnesses, may be only offered radiation therapy as potentially curative treatment for prostate cancer because of the potential for a transfusion. Intraoperative cell salvage (IOCS) is an effective blood management strategy for patients who are not willing to accept predonated autologous or allergenic blood. We present our management for Jehovah's Witness patients with clinically localized prostate cancer, emphasizing our blood management approach. This is the first such report.

Aged↗
PubMedDate not supplied

Staging of primary malignancies of bone.

Staging of bone sarcomas is the process whereby patients are evaluated with regard to histology, as well as the local and distant extent, of disease. Bone sarcomas are staged based on grade, size, and the presence and location of metastases. The system is designed to help stratify patients according to known risk factors. Proper staging helps define the prognosis for patients and helps guide their treatment. Furthermore, staging allows meaningful comparisons to be done among groups of patients.

Bone Neoplasms↗