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Biomedical subjects

R B Womer

Publications and source records attributed to R B Womer.

At least 37 records · Page 2Linked to original sources
PubMed1994

Polymorphism at codon 36 of the p53 gene.

A polymorphism at codon 36 in exon 4 of the p53 gene was identified by single strand conformation polymorphism (SSCP) analysis and direct sequencing of genomic DNA PCR products. The polymorphic allele, present in the heterozygous state in genomic DNAs of four of 100 individuals (4%), changes the codon 36 CCG to CCA, eliminates a FinI restriction site and creates a BccI site. Including this polymorphism there are four known polymorphisms in the p53 coding sequence.

Base Sequence↗
PubMed1992

Residual disease at the end of induction therapy as a predictor of relapse during therapy in childhood B-lineage acute lymphoblastic leukemia.

PURPOSE: More than 95% of children with B-lineage acute lymphoblastic leukemia (ALL) achieve a clinical remission after the induction phase of chemotherapy (first 28 days) as evaluated by morphologic criteria. However, relapse occurs in approximately 30% of these children. The objective of this study was to determine whether the outcome of patients in clinical remission at the end of induction therapy could be predicted using a highly sensitive method to detect residual disease. PATIENTS AND METHODS: All children diagnosed with B-lineage ALL at the Children's Hospital of Philadelphia during a 2-year period were eligible. The extent of residual leukemia was quantitated in remission marrow samples obtained at the end of induction therapy in 44 children using a phage clonogenic assay in association with complementarity-determining-region 3 (CDR3)-polymerase chain reaction (PCR). RESULTS: Residual disease was a significant predictor of outcome independent of WBC count, age, or sex. The estimated relapse-free survival (RFS) during therapy was 50.4% (+/- 12.6%) for patients with high residual disease (> or = 0.6% leukemia cells among total marrow B cells) versus 91.9% (+/- 5.5%) for those with lower levels (P < .002). There were no significant differences in off-treatment RFS between patients with high or low residual disease who completed therapy in continuous remission (P = .82). The overall estimated RFS was 32.3% (+/- 11.6%) for patients with high residual disease versus 62.6% (+/- 10.7%) for patients with lower levels of residual leukemia cells, with a median follow-up of 5.3 years for patients in continuous remission (P < .008). CONCLUSION: PCR detection of high residual disease at the end of induction therapy identifies patients at increased risk for relapse during therapy.

Adolescent↗
PubMed1992

Nasopharyngeal malignancies in children.

A retrospective analysis identified 29 children with nasopharyngeal malignancies who were evaluated at the Children's Hospital of Philadelphia from 1970 through 1989. Rhabdomyosarcoma (15) and carcinoma (9) were the most common tumor types, and there were distinct differences in the clinical presentations of these two malignancies. Patients with rhabdomyosarcoma were generally younger than those with carcinoma and enjoyed longer survival. Six (67%) of the children with carcinoma were black; all of the patients with rhabdomyosarcoma were white. Patients with carcinoma were also more likely to present with cervical metastases. The presentation, evaluation, and methods of treatment for pediatric nasopharyngeal malignancies are discussed.

Adolescent↗
PubMed1992

Osteosarcoma as a second malignant neoplasm in children.

Nine patients who had an osteosarcoma that had developed as a second malignant neoplasm in a previously irradiated site were managed at a major center for the treatment of tumors in children. The doses of radiation had averaged 4144 centigray (range, 2300 to 8000 centigray) and chemotherapy had been administered, when appropriate, for the primary malignant lesion (Ewing sarcoma, malignant fibrous histiocytoma, Hodgkin lymphoma, neuroblastoma, neurofibrosarcoma, rhabdomyosarcoma, and Wilms tumor). The interval between the initial treatment and the diagnosis of the secondary sarcoma averaged ten years and one month (range, five years and ten months to twenty-one years and nine months). Three patients were alive, two of them with active disease, at the time of writing. The other six had died within three years (average, fifteen months) after the second diagnosis. The prevalence of secondary osteosarcoma is increasing as the survival of children who have a malignant lesion increases. Plans for tumor therapy should take into account the risk of this complication, which is usually fatal.

Adolescent↗
PubMed1991

Structure and expression of the beta-platelet-derived growth factor receptor gene in human tumor cell lines.

Southern digests of DNA from 15 human connective tissue tumor-derived cell lines (and cell strains) and from peripheral blood lymphocytes from normal volunteers were prepared to compare structure of the beta-platelet-derived growth factor receptor gene in normal and tumor-derived cells. The tumor-derived samples had no alterations in gene structure, nor was gene amplification evident. Two restriction fragment length polymorphisms were detected within the beta-receptor gene. Expression of the alpha- and beta-platelet-derived growth factor receptor was quantified using Northern blots. Expression was not tumor-type specific. For example, one rhabdomyosarcoma cell line expressed only the alpha-receptor, whereas two others expressed the beta. In contrast, a human fibroblast cell strain expressed both receptor types. Alterations in receptor expression may be a result of the tumorigenic process.

Alleles↗
PubMed1991

Molecular and cytogenetic analysis of chromosomal arms 2q and 13q in alveolar rhabdomyosarcoma.

We present cytogenetic and molecular genetic analyses of two cases of alveolar rhabdomyosarcoma. The characteristic translocation between chromosomes 2 and 13, t(2;13)(q35;q14), has been identified in both cases. Using cell lines derived from these tumor specimens, we have performed Southern blot analysis to investigate the possibility of rearrangement of 14 candidate genes mapping to the relevant regions of 2q and 13q. These candidate genes can be divided into 5 groups: signal transduction proteins (RB1, inhibin alpha, FLT1, and HOX4B), muscle-specific products [myosin light chain, desmin, and nicotinic cholinergic receptor subunits gamma and delta (CHRNG and CHRND)], extracellular matrix proteins (collagen type VI alpha 3 chain, elastin, and fibronectin), transformation-associated products (intestinal alkaline phosphatase and L-plastin), and other genes (esterase D). Conventional gel electrophoresis followed by Southern blot analysis indicated no evidence of rearrangement within or near these genes except for a rearrangement in the CHRNG-CHRND locus, which occurred only in a subpopulation of the late recurrence tumor cells of one patient. In addition, we employed pulsed-field gel electrophoresis-Southern blot analysis to demonstrate the absence of detectable rearrangements within a larger region around each of these genes.

Abdominal Neoplasms↗
PubMed1991

The cellular biology of bone tumors.

New knowledge in cell and molecular biology has begun to expand the understanding of the biology of osteosarcoma and Ewing's sarcoma. Studies on osteosarcomas have revealed abnormalities in the growth-inhibiting retinoblastoma gene, which may release cells from normal growth control. Abnormalities in growth factor production or response tend to inappropriately activate cell growth. Tumor cell DNA content and cytogenetics may affect the diagnosis and prognostic grouping of osteosarcomas. In Ewing's sarcomas, a characteristic translocation between Chromosomes 11 and 22 has been identified; this translocation is also found in malignant neuroepitheliomas. A variety of studies point to both neuroectodermal and mesenchymal origins for Ewing's sarcomas. Applications of new biologic knowledge and technology to clinical problems will lead to significant changes in the diagnosis, and perhaps in the treatment, of these tumors in the coming years. Collaborations between community and referral center physicians and scientists are critical for continued progress.

DNA, Neoplasm↗
PubMed1990

Minimal residual disease in childhood B-lineage lymphoblastic leukemia. Persistence of leukemic cells during the first 18 months of treatment.

BACKGROUND: Whether patients in clinical remission for acute lymphoblastic leukemia (ALL) continue to harbor leukemic cells is not known, because methods of detecting residual malignant cells have not been sufficiently sensitive. This information might be useful for predicting recurrence and determining the duration of therapy. METHODS: Using a sensitive new method--identifying complementarity-determining region III sequences with the polymerase chain reaction--we estimated the number of residual leukemic cells in the bone marrow of eight children with B-lineage lymphoblastic leukemia before and after remission. RESULTS: Induction chemotherapy produced a 3-to-4-log reduction in the number of leukemic cells. In all samples obtained up to 18 months after diagnosis, however, 0.004 to 2.6 percent of bone marrow nucleated cells were residual leukemic cells. Among the four patients studied more than 18 months after diagnosis, three had no detectable leukemic cells in marrow samples. Despite this, one of them, who was no longer receiving therapy, had a central nervous system relapse. In one patient receiving maintenance chemotherapy, there was a 60-fold increase in leukemic cells three months before bone marrow relapse. CONCLUSIONS: The complete disappearance of leukemic cells (or their reduction below our method's threshold of detection, 1 in 100,000 cells) may be necessary to achieve a cure of ALL. The quantification of residual leukemic cells in serial marrow aspirates during therapy may allow the early detection of relapse.

Adolescent↗
PubMed1990

Rhabdomyosarcoma of the head and neck in children.

Rhabdomyosarcoma is the most common soft-tissue sarcoma in infants and children, with the head and neck being the most frequent site of involvement. Treatment for this neoplasm has undergone many changes, with a much improved prognosis using a combination of surgery, radiation therapy, and chemotherapy. This retrospective analysis presents the management and outcome of 60 children (aged 3 months to 18 years) with rhabdomyosarcoma of the head and neck evaluated at the Children's Hospital of Philadelphia (Pa) between 1970 and 1987. The overall death rate for all head and neck sites decreased from 50% in 1970 to 1979 to 23% in 1980 to 1987, reflecting the improved management protocol.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1989

Complex karyotypes in a series of pediatric osteosarcomas.

Cytogenetic analysis was performed on eight osteosarcomas, including six primary untreated biopsies, one second primary in a patient with a history of undifferentiated sarcoma, and one recurrent lung metastasis. Two primary tumors and the peripheral blood lymphocytes from all eight patients had normal karyotypes. Six of the tumors demonstrated extremely complex karyotypes, with modal numbers in the hypodiploid, triploid, and hypertetraploid ranges. The predominant types of structural abnormalities observed were nonreciprocal translocations and deletions, which differed between cases. A consistent loss of normal chromosome 13 homologs was evident in the six cases with abnormal tumor karyotypes; however, chromosomal loss was not restricted to #13. Molecular studies of osteosarcoma, especially with regard to the retinoblastoma locus on chromosome 13, should take into consideration the complex cytogenetic changes seen in this tumor.

Adolescent↗
PubMed1988

Platelet-derived growth factor-induced c-myc RNA expression. Analysis of an inducible pathway independent of protein kinase C.

Platelet-derived growth factor (PDGF) is generally considered to stimulate phosphoinositide turnover resulting in activation of protein kinase C and increased cytoplasmic [Ca2+]. We have examined the role of these secondary effects in regulation of c-myc mRNA accumulation in the MG-63 human osteogenic sarcoma line. Treatment of quiescent cells with 12-O-tetradecanoyl phorbol-13-acetate (TPA) to down-regulate protein kinase C inhibited TPA-stimulated c-myc expression but did not affect the PDGF-modulated process. When cytoplasmic [Ca2+] was increased by addition of a Ca2+ ionophore (A23187 or ionomycin), no stimulation of c-myc RNA was seen; furthermore, these agents did not enhance the PDGF-modulated c-myc expression. Addition of EGTA to cultures treated with both PDGF and a Ca2+ ionophore did not inhibit c-myc induction but rather caused a superinduction of c-myc RNA accumulation. Superinduction occurred only if the [EGTA] was greater than [Ca2+] in the medium. This superinduction was distinct from the increased induction caused by inhibition of protein synthesis. Because PDGF-induced c-myc expression is independent of protein kinase C and increased cytoplasmic [Ca2+], the evidence suggests that PDGF modulates c-myc RNA accumulation in MG-63 cells via a novel pathway, seemingly uncoupled from the classic action of increased phosphoinositide metabolism.

Calcimycin↗
PubMed1987

PDGF induces c-myc mRNA expression in MG-63 human osteosarcoma cells but does not stimulate cell replication.

The platelet-derived growth factor (PDGF) modulated growth response of the MG-63 human osteosarcoma cell line, which neither expresses c-sis mRNA nor secretes a PDGF analogue, was characterized. Scatchard analysis demonstrated that the MG-63 cells have 23,000 receptors per cell with a Kd of 5 X 10(-11) M. The receptor became phosphorylated, in a PDGF concentration-dependent manner, when 32P-orthophosphate-labeled cells were treated with PDGF for 3 h at 4 degrees C. The phosphorylated receptor was identified by autoradiography and gel electrophoresis after isolation of the 32P-labeled receptor using a solid-phase monoclonal antibody directed against phosphotyrosine. Binding of the receptor to the antibody was inhibited by 5 mM phenyl phosphate, further suggesting that PDGF stimulated tyrosine-specific receptor autophosphorylation. In addition, treatment of MG-63 cells with PDGF for 3 h at 37 degrees C induced a 7.5-fold increase in c-myc mRNA accumulation as analyzed on Northern gels. However, MG-63 cells grew equally well in either serum-(which contains PDGF) or plasma-(which does not) supplemented medium. Furthermore, PDGF did not stimulate DNA synthesis in growth arrested MG-63 cells, nor did it potentiate DNA synthesis modulated by somatomedin C. Thus MG-63 cells are a naturally occurring cell variant in which PDGF stimulates c-myc expression but does not modulate mitogenesis.

Animals↗
PubMed1985

Renal toxicity of cisplatin in children.

We measured renal function in 22 children receiving cisplatin as initial treatment for neuroblastoma or malignant germ cell tumors. Glomerular filtration rates were estimated from the plasma clearance of 51Cr-EDTA and were compared with measurements of plasma creatinine concentration and creatinine clearance. The degree of cisplatin-induced renal damage varied widely, and plasma creatinine measurements and creatinine clearances were not reliable guides to glomerular filtration rate. Renal function in children receiving cisplatin should be monitored by measurement of glomerular filtration rate with an isotope clearance technique.

Albuminuria↗
PubMed1985

Healing rates of treated and untreated bone lesions in histiocytosis X.

Evaluation of the response of histiocytosis X to various forms of treatment is difficult, because presentation patterns are protean and the disease can be self-limited. A retrospective evaluation was made of the healing of 42 histiocytosis X bone lesions, in 21 patients treated in variety of ways, using serial radiographs and a semiquantitative scoring system. Treatments included various combinations of surgery (simple biopsy or curettage), radiotherapy (200 to 1,200 centi-Gray [cGy]), chemotherapy (according to various protocols), and local steroid injection. Median times to a given degree of healing were similar across treatment groups and in untreated lesions. It was concluded that mode of treatment does not exert a strong influence on the rate of healing of histiocytosis X bone lesions. Some healing should be apparent 4 months after diagnosis, but complete healing may take many months. Treatment of histiocytosis X bone lesions is indicated only if intense pain or risk of fracture or deformity are present.

Adolescent↗