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C Miyamoto

Publications and source records attributed to C Miyamoto.

89 records · Page 5Linked to original sources
PubMed1985

Production of human c-myc protein in insect cells infected with a baculovirus expression vector.

A cDNA fragment coding for human c-myc was inserted into the genome of the baculovirus Autographa californica nuclear polyhedrosis virus adjacent to the strong polyhedrin promoter. Insect cells infected with the recombinant virus produced significant amounts of c-myc protein, which constituted the major phosphoprotein component in these cells. By immunoprecipitation and immunoblot analysis, two proteins of 61 and 64 kilodaltons were detected with c-myc-specific antisera. The insect-derived proteins were compared with recombinant human c-myc-encoded proteins synthesized in Escherichia coli and Saccharomyces cerevisiae cells. The c-myc gene product was found predominantly in the nucleus by subcellular fractionation of infected insect cells.

Animals↗
PubMed1985

Regulation of the human c-myc gene: 5' noncoding sequences do not affect translation.

The influence of untranslated 5' sequences on c-myc expression was compared by measuring the translational efficiencies of mRNAs which contain leaders derived from exon 1 or intron 1 of the human c-myc gene. Expression plasmids were constructed and introduced into COS cells, and the levels of c-myc mRNA and protein were examined. Our results show that mRNAs transcribed from constructs containing exon 1 or intron 1, which have different folding potential, are translated with approximately equal efficiencies. This suggests that the translation of c-myc mRNA is not controlled by secondary structure alone. In addition, we observed that transcripts in which exon 1 was deleted are not translated more efficiently, but are present at a higher steady-state level. Thus, this example provides evidence for possible control at the transcriptional level. Finally, since the c-myc product was produced in each of our test systems, the results suggest that this protein does not regulate its own transcription or translation via a specific interaction with c-myc exon 1 alone.

Animals↗
PubMed1983

Characteristics of the nascent and non-nascent small DNA molecules found in Escherichia coli.

We have purified nascent DNA molecules from Escherichia coli pulse-labeled with 5-bromo[6-3H]deoxyuridine by repeated chromatography on nitrocellulose and isopycnic centrifugation in CsCl. The nascent molecules were labeled with 32P either at their 5' ends using polynucleotide kinase or at their 3' ends using terminal transferase. Compared to the non-nascent DNA of normal density, the nascent dense DNA contained a higher proportion of molecules terminated at their 5' ends with ribonucleotides. Exposure of the dense DNA to alkali generated 5' OH termini quantitatively equivalent to the number of molecules bearing 5' ribonucleotides. Experiments designed (1) to detect structures at the 5' ends of phosphatase-treated nascent DNA molecules that caused them to be resistant to hydrolysis by spleen exonuclease or (2) to detect polypeptides that were associated covalently with small DNA molecules and could be iodinated with the Bolton-Hunter reagent did not yield positive results. We conclude that many, if not all, of the intermediates in E. coli DNA replication are initiated with one or more ribonucleotides. The nascent molecules are outnumbered by small non-nascent DNA molecules in the cell, many of which appear to become slightly longer when cells are pulsed with thymidine. Many of the non-nascent DNA molecules behave as if they were self-complementary or crosslinked.

Bromodeoxyuridine↗
PubMed1975

Effects of SR-spirochete infection on Drosophila melanogaster carrying intersex genes.

Three sex-transforming genes (ix, tra-D, and dsx) in D. melanogaster were examined with respect to possible interactions with the NSR strain SR-spirochetes. The SR-spirochetes exerted a lethal effect on XY but not on XX individuals, regardless of whether they were phenotypically males, intersexes, or females. These results, taken together with those reported by Sakaguchi and Poulson (1963)on tra and 2X3A intersexes, both of which are resistant to the androcidal action of SR-spirochetes, support the interpretation that male susceptibility is a consequence of the single X condition.

Animals↗
PubMedDate not supplied

The role of Tc-99m HMPAO functional brain imaging in detection of cerebral radionecrosis.

BACKGROUND: Cerebral radionecrosis is a possible complication of brain radiation therapy in patients with primary or metastatic tumors. This retrospective study evaluated the role of Tc-99m hexamethyl propyleneamine oxime (HMPAO) scintigraphy in monitoring the effects of radiation on the brain. METHODS: Ninety-eight patients (41 female, 57 male) with a mean age of 51 years (range, 16-82 years) underwent 128 sets of single-photon emission computed tomography studies. TI-201 and Tc-99m HMPAO single-photon emission computed tomography studies were performed for tumor localization and evaluation of the effect of radiation on the cerebral cortex. Thirty concomitant neuropsychological tests and 96 anatomic imaging (computed tomography/magnetic resonance imaging) were performed. The average radiation dose was 52 Gy delivered as 1.8 to 2 Gy/fraction. Thirty-two patients received an average dose of 160 mCi of I-125 EGFr concomitantly. The average follow-up period was 34 months. Abnormalities away from the tumor site were interpreted as positive on HMPAO studies, neuropsychological testing, or anatomic imaging; otherwise, they were classified as negative. RESULTS: There were 10/45 (22%) and 75/83 (90%) abnormal HMPAO study results before and after radiation therapy. The HMPAO studies compared with neuropsychological testing showed 3/13 (23%) and 14/17 (82%) concordant abnormalities in addition to tumor site in patients pre- versus postradiation therapy. There was better concordance of HMPAO and anatomic imaging in 22/30 (76%) patients versus 24/67 (36%) patients before radiation therapy. HMPAO imaging after radiation therapy revealed significantly more perfusion abnormalities. There were significant differences between all of the aforementioned parameters. CONCLUSION Tc-99m HMPAO imaging is useful in the evaluation of the effects of radiation therapy on the brain and is highly concordant with neuropsychological testing. It is superior to anatomic studies in identifying radiation-induced changes.

Adolescent↗