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Biomedical subjects

B C Turner

Publications and source records attributed to B C Turner.

At least 37 records · Page 2Linked to original sources
PubMed1998

Effective treatment of stage I uterine papillary serous carcinoma with high dose-rate vaginal apex radiation (192Ir) and chemotherapy.

PURPOSE: Uterine papillary serous carcinoma (UPSC) is a morphologically distinct variant of endometrial carcinoma that is associated with a poor prognosis, high recurrence rate, frequent clinical understaging, and poor response to salvage treatment. We retrospectively analyzed local control, actuarial overall survival (OS), actuarial disease-free survival (DFS), salvage rate, and complications for patients with Federation International of Gynecology and Obstetrics (FIGO) (1988) Stage I UPSC. METHODS AND MATERIALS: This retrospective analysis describes 38 patients with FIGO Stage I UPSC who were treated with the combinations of radiation therapy, chemotherapy, total abdominal hysterectomy, and bilateral salpingo-oophorectomy (TAH/BSO), with or without a surgical staging procedure. Twenty of 38 patients were treated with a combination of low dose-rate (LDR) uterine/vaginal brachytherapy using 226Ra or 137Cs and conventional whole-abdomen radiation therapy (WART) or whole-pelvic radiation therapy (WPRT). Of 20 patients (10%) in this treatment group, 2 received cisplatin chemotherapy. Eighteen patients were treated with high dose-rate (HDR) vaginal apex brachytherapy using 192Ir with an afterloading device and cisplatin, doxorubicin, and cyclophosphamide (CAP) chemotherapy (5 of 18 patients). Only 6 of 20 UPSC patients treated with combination LDR uterine/vaginal brachytherapy and conventional external beam radiotherapy underwent complete surgical staging, consisting of TAH/BSO, pelvic/para-aortic lymph node sampling, omentectomy, and peritoneal fluid analysis, compared to 15 of 18 patients treated with HDR vaginal apex brachytherapy. RESULTS: The 5-year actuarial OS for patients with complete surgical staging and adjuvant radiation/chemotherapy treatment was 100% vs. 61% for patients without complete staging (p = 0.002). The 5-year actuarial OS for all Stage I UPSC patients treated with postoperative HDR vaginal apex brachytherapy and systemic chemotherapy was 94% (18 patients). The 5-year actuarial OS for Stage I UPSC patients treated with HDR vaginal apex brachytherapy and chemotherapy who underwent complete surgical staging was 100% (15 patients). The 5-year actuarial OS for the 20 Stage I UPSC patients treated with combinations of pre- and postoperative LDR brachytherapy and postop WART was 65%. None of the 6 surgically staged UPSC patients treated with LDR radiation and WART/WPRT developed recurrent disease. For patients with FIGO Stage IA, IB, and IC UPSC who underwent complete surgical staging, the 5-year actuarial DFS by depth of myometrial invasion was 100, 71, and 40%, respectively (p = 0.006). The overall salvage rate for local and distant recurrence was 0%. Complications following HDR vaginal apex brachytherapy included only Radiation Therapy Oncology Group (RTOG) grade 1 and 2 toxicity in 16% of patients. However, complications from patients treated with WART/WPRT, and/or LDR brachytherapy, included RTOG grade 3 and 4 toxicity in 15% of patients. CONCLUSION: Patients with UPSC should undergo complete surgical staging, and completely surgically staged FIGO Stage I UPSC patients can be effectively and safely treated with HDR vaginal apex brachytherapy and chemotherapy. Both OS and DFS of patients with UPSC are dependent on depth of myometrial invasion. The salvage rate for both local and distant UPSC recurrences is extremely poor. Complications from HDR vaginal apex brachytherapy were minimal.

Adult↗
PubMed1997

Insulin-like growth factor-I receptor overexpression mediates cellular radioresistance and local breast cancer recurrence after lumpectomy and radiation.

The insulin-like growth factor-I receptor (IGF-IR) plays a critical role in cell growth regulation and transformation. The radiosensitivity of NIH 3T3 fibroblasts overexpressing either wild-type or mutant IGF-IR was examined. High levels of wild-type IGF-IR conferred radioresistance, and mutational analysis revealed that this effect correlated with the transforming capacity but not the mitogenic activity of the receptor. The radioresistant phenotype was reversed when the cells were incubated with antisense oligonucleotides targeted to IGF-IR mRNA, demonstrating that IGF-IR directly influences radioresistance. The clinical significance of these findings was examined in an immunohistochemical analysis of primary breast tumors, revealing that high levels of IGF-IR in tumor samples were highly correlated with ipsilateral breast tumor recurrence (IBTR) following lumpectomy and radiation therapy (P = 0.001). Subgroup analysis revealed that, for early breast tumor relapses (within 4 years of initial breast tumor diagnosis), elevated levels of IGF-IR were strongly associated with IBTR (P = 0.004) but IGF-IR expression was not prognostic for IBTR from breast cancer patients with late relapses (P was not significant). These studies provide evidence for the influence of IGF-IR on cellular radioresistance and response to therapy and raise the possibility that the radiocurability of selected tumors may be improved by pharmaceutical strategies directed toward the IGF-IR.

3T3 Cells↗
PubMed1995

Cytogenetics of an intrachromosomal transposition in Neurospora.

Knowledge of intrachromosomal transpositions has until now been primarily cytological and has been limited to Drosophila and to humans, in both of which segmental shifts can be recognized by altered banding patterns. There has been little genetic information. In this study, we describe the genetic and cytogenetic properties of a transposition in Neurospora crassa. In Tp(IR-->IL)T54M94, a 20 map unit segment of linkage group I has been excised from its normal position and inserted near the centromere in the opposite arm, in inverted order. In crosses heterozygous for the transposition, about one-fifth of surviving progeny are duplications carrying the transposed segment in both positions. These result from crossing over in the interstitial region. There is no corresponding class of progeny duplicated for the interstitial segment. The duplication strains are barren in test crosses. A complementary deficiency class is represented by unpigmented, inviable ascospores. Extent of the duplication was determined by duplication-coverage tests. Orientation of the transposed segment was determined using Tp x Tp crosses heterozygous for markers inside and outside the transposed segment, and position of the insertion relative to the centromere was established using quasi-ordered half-tetrads from crosses x Spore killer. Quelling was observed in the primary transformants that were used to introduce a critical marker into the transposed segment by repeat-induced point mutation (RIP).

Centromere↗
PubMed1993

Interleukin 2 regulates Raf-1 kinase activity through a tyrosine phosphorylation-dependent mechanism in a T-cell line.

Previously we found that interleukin 2 (IL-2) induces tyrosine phosphorylation and activation of the serine/threonine-specific kinase encoded by the raf-1 protooncogene in a T-cell line, CTLL-2. Here we extended these findings by exploring the effects of selective removal of phosphate from tyrosines in p72-74-Raf-1 kinase that had been immunoprecipitated from IL-2-stimulated CTLL-2 cells. Treatment in vitro of IL-2-activated Raf-1 with the tyrosine-specific phosphatases CD45 and TCPTP (formerly called T-cell protein tyrosine phosphatase) reduced Raf kinase activity to nearly baseline levels. This effect was completely inhibited by the phosphatase inhibitor sodium orthovanadate. In contrast, treatment of Raf-1 with a serine/threonine-specific phosphatase, protein phosphatase 1 (PP-1), resulted in a more modest decrease in Raf in vitro kinase activity, and this effect was prevented by okadaic acid. Two-dimensional phosphoamino acid analysis confirmed the selective removal of phosphate from tyrosine by CD45 and from serine and threonine by PP-1. The immunoreactivity of p72-74-Raf-1 with anti-phosphotyrosine antibodies was also completely abolished by treatment with CD45 in the absence but not in the presence of sodium orthovanadate. These findings provide evidence that the IL-2-stimulated phosphorylation of Raf-1 on tyrosines plays an important role in upregulating the activity of this serine/threonine-specific kinase in CTLL-2 cells and, as such, provides a model system for studying the transfer of growth factor-initiated signals from protein tyrosine kinases to serine/threonine-specific kinases.

Animals↗
PubMed1993

Protooncogene-encoded protein kinases in interleukin-2 signal transduction.

Protooncogenes are the normal forms of cellular genes that when altered in their expression or coding sequences can contribute to neoplastic transformation. As these genes often are important for normal cellular growth control, we explored the possibility that protein kinases encoded by particular protooncogenes could participate in signal transduction pathways regulated by the T cell growth factor, interleukin-2 (IL-2). In this review we summarize our findings to date regarding Raf-1, a serine/threonine-specific kinase that becomes phosphorylated on tyrosine residues and enzymatically activated in response to IL-2 stimulation. In addition, we describe our investigations of Lck and Lyn, two closely related protein tyrosine kinases of the src gene family that physically associate with the IL-2 receptor complex and whose activities are regulated by IL-2 in at least some T cells and B cells, respectively.

Animals↗
PubMed1991

Differential regulation of the p72-74 RAF-1 kinase in 3T3 fibroblasts expressing ras or src oncogenes.

The c-raf-1 protooncogene encodes a p72-74 serine/threonine-specific kinase that has been implicated in growth factor-mediated signal transduction and malignant transformation. Here, we compared the effects of Ha-c-ras and v-src oncogenes on the regulation of p72-74 RAF-1 kinase in NIH3T3 cells. In both serum-starved and platelet-derived growth factor-treated v-src-transformed cells, the RAF-1 kinase was constitutively activated, displaying characteristic retarded mobility in electrophoretic gels and elevated activity in in vitro kinase assays. In contrast, the RAF-1 protein from quiescent ras-transformed cells did not exhibit constitutively shifted gel mobility or elevated kinase activity but did respond normally with regard to platelet-derived growth factor- and phorbol myristate acetate-induced changes in p72-74 RAF-1 phosphorylation and kinase activity. 3T3 cells transformed by ras, however, contained elevated levels of p72-74 RAF-1 protein (as determined by immunoblotting), suggesting an indirect influence on this kinase. Quantitative differences in the levels and subcellular distribution of immunodetectable protein kinase C enzymes did not account for the differences between src- and ras-transformed 3T3 cells with regard to regulation of the RAF kinase. These findings in serum-deprived 3T3 cells demonstrate that expression of a ras oncogene can be insufficient for full activation of the p72-74 RAF-1 kinase, implying necessity for an additional growth factor-mediated stimulus.

Animals↗
PubMed1990

Dysplasia and cancer complicating strictures in ulcerative colitis.

Previous studies have found a widely variable prevalence of dysplasia and cancer in colonic strictures in patients with ulcerative colitis. Consequently, therapeutic recommendations are conflicting. To better assess the prevalence, we reviewed the clinical and pathological findings in all 27 patients with ulcerative colitis complicated by stricture who were entered into our Inflammatory Bowel Disease Registry. A true stricture was defined as a persistent localized narrowing of the colon found on air-contrast barium enema or on colonoscopy. Upon careful review, 12 of 27 patients were found to have transient colonic spasm, not a stricture, and were excluded. The remaining 15 patients with true strictures represented 3.2% of all ulcerative colitis patients in the registry. Strictures were identified at 13.3 +/- 9.9 years following the diagnosis of ulcerative colitis. Eleven patients had multiple strictures that were principally located in the left colon. Of the 15 patients, 11 had dysplasia and two had cancer found on colonoscopic biopsy. Ultimately, six patients had carcinoma found at colonoscopy or colectomy (three modified Dukes' stage A, one stage B, and two stage D). All cancers were at the site of a stricture. These findings indicate that a true colonic stricture in ulcerative colitis is frequently associated with dysplasia and cancer, which can be diagnosed with colonoscopic biopsy. A stricture should be considered a strong risk factor for cancer, requiring intensive colonoscopic surveillance. If dysplasia is discovered, or if the stricture cannot be adequately biopsied, consideration should be given to total colectomy.

Adult↗
PubMed1987

Recombination block in the Spore killer region of Neurospora.

Spore killers Sk-2K and Sk-3K are chromosomal meiotic drive factors in Neurospora. In heterozygous crosses, ascospores not containing the Spore killer die. Sk-2K and Sk-3K, which differ in killing specificity, were found to be associated with suppression of recombination in a centromere-spanning region of linkage group III, and investigation of that recombination block is reported here. The block covers a region that is normally 30 to 40 map units long. A locus (r(Sk-2)) conferring resistance to Sk-2K maps to the left end of the recombination block. Recombination is normal in r(Sk-2) X Sk sensitive but blocked in Sk-2K X r(Sk-2); so the block does not depend upon killing. By selective plating, SkK stocks carrying genetic markers within the block were obtained at frequencies on the order of 10(-5) or 10(-6). Since this tight block is far beyond what has been observed for genetic reduction of recombination, a structural basis is assumed. No evidence of chromosome rearrangement was obtained. Crosses homozygous for Sk-2K show normal crossing-over and map order for the flanking markers cum and his-7 and three included markers (acr-7, acr-2, and leu-1). Results would be consistent with a divergence of sequence great enough to interfere with homologous pairing.

Crosses, Genetic↗
PubMed1968

Pesticide mobility: determination by soil thin-layer chromatography.

Pesticide movement was evaluated by the comparison of R(F) values on thin layers of soils. Results from the new technique correlated well with existing information on pesticide movement, facilitating the grouping of pesticides into classes on the basis of mobility. Thin-layer chromatography may have broad applicability in soils research.

Acetates↗
PubMed1966

The chromophore of phytochrome.

The chromophore of phytochrome, the plant photomorphogenic pigment, was cleaved from the associated protein. Chromatographic and spectral properties indicated that it was a bilitriene closely similar to but distinct from the chromophore of C-phycocyanin and allophycocyanin.

Journal Article↗