Search PubMed⌕ Search

Biomedical subjects

J A Fletcher

Publications and source records attributed to J A Fletcher.

At least 19 recordsLinked to original sources
PubMed1996

Comparison between the in vitro intrinsic radiation sensitivity of human soft tissue sarcoma and breast cancer cell lines.

The purpose of this study is to evaluate the radiation sensitivity of human soft tissue sarcoma cell lines in vitro and to compare with that of human breast carcinoma and glioblastoma cell lines. The intrinsic radiation sensitivity parameters of seven human soft tissue sarcomas and eight breast carcinoma cell lines were investigated in vitro by clonogenic assays for single-dose irradiation under aerobic conditions on cells in exponential phase of growth. The results for sarcoma cell lines showed that the mean surviving fraction at 2 Gy (SF2) was 0.39 (SD +/- 0.09) with a range of 0.24 to 0.53, and the average mean inactivation dose (MID) was 1.92 (SD +/- 0.35) range from 1.36 Gy to 2.49 Gy. These values were not different from that of breast cell lines examined concurrently and using the same experimental methods (mean SF2 0.38, SD +/- 0.09; MID 1.9 Gy, SD +/- 0.37). However radiobiological parameters of nine karyotyped human malignant glioma cell lines determined earlier in this laboratory were significantly higher (mean SF2 0.50 +/- 0.14; mean MID 2.61 +/- 0.60). In conclusion, the data presented here do not support the view that cells of sarcomas show unusual radiation resistance. To the extent that the in vitro determined cellular radiation sensitivity reflects the tumor response in vivo, the success rate for radiation applied against sarcoma and breast carcinoma of comparable size could be similar.

Breast Neoplasms↗
PubMed1996

Isochromosome 7q in adult Wilms' tumor.

We describe cytogenetic and histologic findings in a Wilms' tumor resected from a 37-year-old man. The tumor karyotype was 45,X,-Y,i(7)(q10). These findings are notable because overrepresentation of chromosome 7 long arm material, i(7)(q10) in particular, has been described recently as a nonrandom event in pediatric Wilms' tumors. The present case suggests a shared genetic pathway in the initiation or progression of some pediatric and adult Wilms' tumors.

Adult↗
PubMed1996

Percutaneous biopsy for prognostic testing of neuroblastoma.

PURPOSE: To determine whether percutaneous biopsy can provide the diagnostic and prognostic information necessary to treat children with advanced neuroblastoma. MATERIALS AND METHODS: From 1991 through 1995, 21 percutaneous biopsies were performed in 20 children with advanced neuroblastoma by using 15- or 16-gauge core biopsy needles. An average of six samples were obtained. Since September 1994, fresh tissue was sent to the reference laboratory, where touch preparations were prepared for N-myc evaluation. RESULTS: Histologic confirmation and prognostic information (Shimada classification) were obtained in all cases. Genetic prognostic information was obtained in 19 patients (95%), DNA index (ploidy) in 18 (90%), N-myc gene expression in 14 (70%), and cytogenetic analysis in 10 (50%). N-myc and ploidy determinations were successful in all five biopsy specimens obtained since September 1994. CONCLUSION: Percutaneous biopsy of advanced neuroblastoma is a feasible alternative to open biopsy.

Adolescent↗
PubMed1996

Synovial sarcoma: prognostic significance of tumor size, margin of resection, and mitotic activity for survival.

PURPOSE: The present study serves to describe outcomes-based prognostic variables characteristic of synovial cell sarcoma. PATIENTS AND METHODS: An analysis was performed of a prospectively compiled data base of 48 consecutive patients with extremity and truncal synovial sarcomas seen between 1966 and 1994. RESULTS: No local recurrences were observed among 27 patients who presented with localized primary disease. Patients with synovial sarcoma less than 5 cm in size has a cancer-specific survival rate at 10 years of 100%, compared with a 10-year survival rate of 32% and 0% for those with sarcoma 5 to 10 cm and greater than 10 cm, respectively (P = .002). Patients with synovial sarcoma with less than 10 mitoses per 10 high-power fields (hpf) had a 10-year cancer-specific survival rate of 46%, compared with a 10-year survival rate of 14% for those with sarcomas with greater than 10 mitoses per hpf (P = .04). Patients with a clean margin of excision were found to have a 10-year cancer-specific survival rate of 43%, compared with 0% for those with microscopic positive margins (P = .03). Among 14 patients treated with neoadjuvant chemotherapy, seven (50%) had objective responses. CONCLUSION: Local control for patients with nonmetastatic disease was excellent. The overall cancer-specific survival rate for patients with localized synovial sarcoma was 34% at 10 years. Primary tumor size, margin of resection, and mean mitotic activity were prognostic factors for survival in synovial sarcoma. There was a high objective response rate to treatment with neoadjuvant chemotherapy; however, there was no detectable beneficial effects on survival in the subset of patients treated with chemotherapy versus nonrandomized patients who received no chemotherapy. Patients with synovial sarcoma > or = 5 cm in size, microscopic positive margins, and/or mean mitotic activity greater than 10 mitoses per 10 hpf should be targeted for new therapeutic studies.

Adult↗
PubMed1996

Cytogenetics and molecular biology of soft tissue tumors.

Characteristic genetic aberrations have been identified in many soft tissue tumors, and it is likely that several of these aberrations, e.g., the translocation of chromosomes X and 18 in synovial sarcoma, will play an increasing diagnostic role. It is fascinating that most of the consistent soft tissue tumor translocations result in fusion genes, and these fusion genes encode proteins, which in turn regulate the expression of other genes. Thus, many soft tissue tumor translocations represent the first steps in complicated cascades of events contributing to deregulated tumor cell growth. Although a number of translocations appear to be useful in diagnosis, it should be emphasized that cytogenetic and molecular detection of chromosome translocations and gene fusions is not always straightforward. Cytogenetic and molecular analyses are perhaps best reserved for the subgroup of undifferentiated small round cell or spindle cell sarcomas, which remain unclassified after histological, immunohistochemical, and ultrastructural studies. Tumor specimens frozen at -70 degrees C can be used subsequently for FISH and PCR studies, although the opportunity to karyotype such specimens is lost upon freezing.

Chromosome Aberrations↗
PubMed1995

Detection of chromosome 18 rearrangement in synovial sarcoma by fluorescence in situ hybridization.

Fluorescence in situ hybridization (FISH) evaluations of chromosome 18 were performed in synovial sarcoma, hemangiopericytoma, and mesothelioma. Each case was evaluated with centromeric and whole chromosome paint probes. The synovial sarcomas had t(X;18) cytogenetically, but the FISH evaluator was blinded to the cytogenetic results and to the histopathologic diagnosis. The FISH analyses were consistent with chromosome 18 translocation in 6 of 7 synovial sarcomas, 0 of 3 hemangiopericytomas, and 0 of 1 mesothelioma. These findings support the use of FISH in the diagnosis of synovial sarcoma.

Chromosomes, Human, Pair 18↗
PubMed1995

Codeletion of p15 and p16 in primary malignant mesothelioma.

The p15 and p16 CDK4 inhibitor genes map within the chromosome band 9p21 region deleted frequently in malignant mesothelioma and other cancers. p16 has been implicated recently as a potential target of 9p21 deletions in mesothelioma, but the role of this gene is uncertain because deletions have been detected more often in established cell lines than in primary tumor specimens. We determined p15 and p16 copy number by fluorescence in situ hybridization with a P1 contig in 50 primary mesotheliomas. Codeletion of p15 and p16 was found in 72% of mesotheliomas, including all cases with spindle-cell components (n = 21) and total deletion of p15 and p16 was found in several mesotheliomas that lacked cytogenetic deletion of the chromosome 9 short arm. Point mutations were not found, however, in exon 2 of retained p15 and p16 alleles from seven mesotheliomas. These findings demonstrate that p15, p16 and/or a closely neighboring gene, are the targets of frequent chromosome 9p deletion in primary malignant mesothelioma.

Base Sequence↗
PubMed1995

Codeletion of p15 and p16 genes in primary non-small cell lung carcinoma.

Chromosome band 9p21 is deleted frequently in non-small cell lung carcinoma (NSCLC), and the p15 and p16 cyclin-dependent kinase-4 inhibitor genes map within this deletion region. Recent studies demonstrated deletion of p15 and p16 in NSCLC metastases and cell lines, suggesting a role for these genes in NSCLC progression. We now report p15 and p16 copy number, as determined by fluorescence in situ hybridization with a P1 contig, in 18 primary NSCLCs. Codeletion of p15 and p16 was found in 15 of 18 NSCLCs, and 1 of the 3 tumors with normal p15 and p16 copy number had a nonsense mutation in exon 2 of p16. We conclude that p15 and p16 are deleted and/or mutated in most primary NSCLCs. Two observations, however, support the involvement of at least one additional tumor suppressor gene on chromosome 9. These observations are: (a) the large size (> 100 kb) of most NSCLC p15/p16 deletions; and (b) the absence of exon 2 mutations in most retained NSCLC p15 and p16 alleles.

Adult↗
PubMed1995

Disruption of the architectural factor HMGI-C: DNA-binding AT hook motifs fused in lipomas to distinct transcriptional regulatory domains.

Lipomas are one of the most common mesenchymal neoplasms in humans. They are characterized by consistent cytogenetic aberrations involving chromosome 12 in bands q14-15. Interestingly, this region is also the site of rearrangement for other mesenchymally derived tumors. This study demonstrates that HMGI-C, an architectural factor that functions in transcriptional regulation, has been disrupted by rearrangement at the 12q14-15 chromosomal breakpoint in lipomas. Chimeric transcripts were isolated from two lipomas in which HMGI-C DNA-binding domains (AT hook motifs) are fused to either a LIM or an acidic transactivation domain. These results, identifying a gene rearranged in a benign neoplastic process that does not proceed to a malignancy, suggest a role for HMGI-C in adipogenesis and mesenchyme differentiation.

Amino Acid Sequence↗
PubMed1995

Identification of a YAC spanning the translocation breakpoints in uterine leiomyomata, pulmonary chondroid hamartoma, and lipoma: physical mapping of the 12q14-q15 breakpoint region in uterine leiomyomata.

Uterine leiomyomata are the most common tumors in women and can cause abnormal uterine bleeding, pelvic pain, and infertility. Approximately 200,000 hysterectomies are performed annually in the U.S. to relieve patients of the medical sequelae of these benign neoplasms. Our efforts have focused on cloning the t(12;14)(q14-q15;q23-q24) breakpoint in uterine leiomyoma to further our understanding of the biology of these tumors. Thirty-nine YACs and six cosmids mapping to 12q14-q15 have been mapped by fluorescence in situ hybridization to tumor metaphase chromosomes containing a t(12;14). One YAC spanned the translocation breakpoint and was mapped to tumor metaphases from a pulmonary chondroid hamartoma containing a t(12;14)(q14-q15;q23-q24) and a lipoma containing a t(12;15)(q15;q24); this YAC also spanned the breakpoint in these two tumors, suggesting that the same gene on chromosome 12 may be involved in the pathobiology of these distinct benign neoplasms.

Base Sequence↗
PubMed1995

Translocation t(8;13)(p11;q11-12) in stem cell leukemia/lymphoma of T-cell and myeloid lineages.

An unusual hematologic neoplasia has been described recently in which the predominant clinical features include T-cell lymphoma, myeloid hyperplasia, and eosinophilia. The multilineage involvement in this disorder suggests transformation of a primitive stem cell. Abnormal karyotypes have been described in three such cases, including one case with t(8;13)(p11.2;q12) and a second case with t(8;13)(p23;q14). We report translocation of chromosomes 8 and 13 in lymph node karyotypes from two patients with this syndrome. Fluorescence in situ hybridization confirmed an identical translocation, t(8;13)(p11;q11-12), in lymphoma cells from each patient. The translocation breakpoints are of particular interest because the FLT3 receptor tyrosine kinase gene has been mapped 13q12. FLT3 is expressed highly in hematopoietic progenitor cells and in myeloid and lymphoid acute leukemias.

Adolescent↗
PubMed1995

Cytogenetic and histologic findings in 17 pulmonary chondroid hamartomas: evidence for a pathogenetic relationship with lipomas and leiomyomas.

Pulmonary chondroid hamartomas (PCH) are benign tumors that contain mesenchymal and epithelial components. In this series, we identified clonal chromosome aberrations in mesenchymal cells from 10 of 17 PCH. Chromosome band 12q15 was rearranged most frequently (N = 4), and one case had a t(12;14)(q15;q24) that was identical cytogenetically to the characteristic translocation in uterine leiomyomas. Histologic review revealed diverse mesenchymal populations, including undifferentiated cells, cartilage, adipose tissue, and smooth muscle, in most of the PCH. These findings suggest that PCH result from neoplastic transformation of a primitive mesenchymal cell that differentiates along chondroid, adipose, and smooth muscle pathways.

Adult↗
PubMed1995

Characterization of human ovarian surface epithelial cells immortalized by human papilloma viral oncogenes (HPV-E6E7 ORFs).

Primary human ovarian surface epithelial (HOSE) cells were immortalized by a retroviral vector (LXSN-16E6E7) expressing HPV-E6E7 open reading frames (ORF). Immortalizations of primary ovarian epithelial cells were achieved in three of three attempts. Detailed analysis was carried out in one line, HOSE 6-3, selected on the basis of its epithelial morphology. The immortalized line (HOSE 6-3) was nontumorigenic in nude mice when examined at subculture number 20. Cytogenetic analysis confirmed its human origin and detailed karyotypic analysis revealed a mixed karyotype made up of about 60% of diploid and 40% of near-tetraploid cells. Clonal chromosomal aberration was observed in a subpopulation of cells involving a ring chromosome number 9. Immunofluorescence and two-dimensional gel electrophoresis revealed the presence of vimentin and several species of cytokeratin (K7, K8, K18, K19). The profile of the cytoskeletal filaments of HOSE 6-3 cells is largely identical with that of normal ovarian epithelial cells before immortalization. The immortalized ovarian epithelial cells have a lower sensitivity to TGF-beta 1 inhibition compared to normal ovarian epithelial cells. The immortalized line, HOSE 6-3, has altered growth properties including a higher proliferation rate, plating efficiency, and saturation density. The establishment of a continuous line of human ovarian epithelial cells may provide an in vitro model for study of carcinogenesis in human ovarian cancers.

Cell Division↗
PubMed1995

Chromosome aberrations in desmoid tumors. Trisomy 8 may be a predictor of recurrence.

Cytogenetic analyses of short-term cultures revealed clonal chromosome aberrations in 6 of 13 desmoid tumors. These aberrations included two consistent events, trisomy 8 (n = 4) and trisomy 20 (n = 3), which have not been reported previously in desmoid tumors. Because trisomy 8 was found in two recurrent desmoid tumors, we used fluorescent in situ hybridization (FISH) methodology to evaluate chromosome 8 in 25 paraffin-embedded and frozen desmoid specimens. The FISH studies demonstrated that both patients with cytogenetic trisomy 8 at the time of recurrence also had had trisomy 8 in primary tumors 4 years earlier. The proportion of trisomy 8 cells in these cases did not change substantially between original diagnosis and recurrence. The FISH studies also revealed trisomy 8 in one recurrent desmoid tumor which had been cytogenetically unremarkable and revealed trisomy 8 in one recurrent desmoid that had not been karyotyped. Four of six patients with trisomy 8 had been followed for more than 1 year, and the desmoid tumors in each of these 4 patients recurred. By contrast, recurrence was noted in only 2 of 17 patients whose desmoid tumors lacked trisomy 8. Our findings demonstrate that trisomy 8 and trisomy 20 are nonrandom aberrations in desmoid tumors. Trisomy 8 appears to be associated with an increased risk of recurrence.

Adult↗
PubMed1995

Ring chromosomes in dermatofibrosarcoma protuberans are composed of interspersed sequences from chromosomes 17 and 22.

Ring chromosomes are found in most dermatofibrosarcoma protuberans (DFSPs), and recent reports demonstrate that portions of the DFSP ring chromosomes derive from chromosome 17. In this study we characterized ring chromosomes in three DFSPs using a combined approach of karyotyping, chromosome painting, and comparative genomic hybridization. Chromosome painting demonstrated that the ring chromosomes in each DFSP were composed of discontinuous, interwoven sequences from chromosomes 17 and 22. Amplification of chromosomes 17 and 22 sequences was confirmed in each of these cases by comparative genomic hybridization, and over-representation of chromosomes 17 and 22 sequences was also demonstrated by comparative genomic hybridization in 1 of 2 cytogenetically unremarkable DFSPs. We conclude that amplification of chromosomes 17 and 22 sequences, in ring form, is a characteristic aberration in DFSP.

Adult↗
PubMed1995

Novel fluorescence in situ hybridization approaches in solid tumors. Characterization of frozen specimens, touch preparations, and cytological preparations.

Fluorescence in situ hybridization has emerged as an extremely important tool for detection and characterization of nonrandom chromosome aberrations in cancer. Fluorescence in situ hybridization assays have been very reliable in cytogenetic tumor preparations, but have been more unpredictable in archival, paraffin-embedded specimens. We describe novel approaches for detection of chromosome aberrations in frozen tumor specimens, touch preparations, and cytological preparations. These approaches are both simple and reproducible, with minimal case-to-case variation in hybridization efficiency or hybridization signal quality. We demonstrate potential applications of these novel approaches by evaluating: 1) significance of normal karyotypes in malignant peripheral nerve sheath tumors; 2) p15/p16 copy number in prostate cancer; and 3) clonal chromosome 3p deletion in cytological preparations of pleural fluid from patients with mesothelioma.

Centromere↗
PubMed1995

A polymerase chain reaction assay for non-random X chromosome inactivation identifies monoclonal endometrial cancers and precancers.

We hypothesize that endometrial carcinoma and their precursors share a monoclonal growth pattern and tested this thesis with archival paraffin-embedded tissues using a polymerase chain reaction-based assay for non-random X chromosome inactivation. Of the 10 well-differentiated endometrial adenocarcinoma cases with heterozygous markers (HUMARA, X-linked androgen receptor gene), 9 had skewed X inactivation consistent with a monoclonal process, and one contained a structurally altered HUMARA gene. X inactivation skewing similar to that of the tumor was seen in matched control polyclonal tissues of 4 (of 9) cases, caused by the small number of endometrial stem cells at the time of embryonic X inactivation. When the polymerase chain reaction assay was applied to four potential endometrial precancers (atypical endometrial hyperplasia) and matched control tissues, two were inconclusive, and two were found to be monoclonal. We conclude that 1) it is essential to include polyclonal control tissues in X inactivation analyses to determine whether skewing is a specific indicator of monoclonality; and 2) endometrial adenocarcinomas and some putative precancers, atypical endometrial hyperplasia, are monoclonal.

Adenocarcinoma↗