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Volume 13 (1994)
- Issue 4 Pages 171-
- Issue 3 Pages 123-
- Issue 2 Pages 91-
- Issue 1 Pages 18-
Volume 13, Issue 2
Displaying 1-4 of 4 articles from this issue
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Seigo Kishikawa, Mitsutaro Akao, Keiko Kuroda, Motonobu Hara, Masafumi ...1994 Volume 13 Issue 2 Pages 91-96
Published: June 30, 1994
Released on J-STAGE: November 13, 2012
JOURNAL FREE ACCESSAn immunocytochemical study was made to compare the aflatoxin B1-induced rat liver tumor cells with normal rat liver cells in vitro with regard to the development of intermediate filaments, cytokeratin and vimentin. Both intermediate filaments were localized at a perinuclear region of the cytoplasm in the cultured tumor cells, while they were diffusely distributed in the cultured normal liver cells. In the metastatic tumor cells (AFB-1), a part of vimentin filaments extended to form networks among adjacent cells and electron microscopic examination showed a figure that vimentin filaments were connected at an intercellular attachment structure, desmosome. When the tumor cells were transplanted subcutaneously in the syngeneic rats, vimentin was scarecely detected in the tumor nodule of the non-metastatic tumor cells (JB1) but they were still present in that of the metastatic tumor cells (AFB-1). These results suggest that the enhanced and localized development of intermediate filaments could be a measure of the malignant progression of rat liver cells.View full abstractDownload PDF (1898K) -
Susumu Takayama, Tatsuro Yoshioka1994 Volume 13 Issue 2 Pages 97-104
Published: June 30, 1994
Released on J-STAGE: November 13, 2012
JOURNAL FREE ACCESSThe improvement of the osmium-thiocarbohydrazide (OTO) technique which is necessary for utilizing chromosome preparations made by the air-drying method for scanning electron microscopy (SEM) was successfully carried out. It was found that air-drying at lower temperature, freshness of air-dried preparations and an appropriate amount of osmium deposit were desirable to make useful SEM preparations. In order to examine higher order structures of metaphase chromosomes, mammalian cells cultured under the different experimental conditions were used. The resultant SEM images together with stereo viewing revealed that metaphase packing is achieved by the compaction through helical coiling of a chromatid fiber of 200-400 nm in diameter which is in turn composed of radial loops of a 30 nm chromatin fiber and that the looped chromatin fiber is quite stable but highly flexible in nature.View full abstractDownload PDF (3320K) -
Takahiko Suzuki, Youji Mitsui1994 Volume 13 Issue 2 Pages 105-111
Published: June 30, 1994
Released on J-STAGE: November 13, 2012
JOURNAL FREE ACCESSTo elucidate the mechanisms of cardiac myocyte cellular hypertrophy and induction of rhythmic contraction, we developed a serum-free culture system for neonatal rat cardiac myocytes. Cellular hypertrophy was elicited by a sympathetic hormone, norepinephrine (NE), phorbol-12,13-dibutyrate (PDBu), and serum. The hypertrophic effect. of NE was inhibited by prazocine, an acadrenergic receptor blocker. However, seruminduced hypertrophy was not inhibited by adrenergic receptor blockers. Hypertrophic stimulation induced by NE, PDBu and serum were inhibited by staurosporine, a protein kinase inhibitor, indicating that protein kinase C activation is involved in cardiac myocyte hypertrophy. Endothelin-1 (ET-1), a novel vasoconstrictor, also elicited cardiac myocyte cellular hypertrophy and strong rhythmic contraction. The cellular hypertrophy induced by ET-1 was also mediated by protein kinase C activation, because the effect was attenuated by H-7, a protein kinase C inhibitor. Conversely, ET-1-induced rhythmic contraction of cardiac myocytes was strongly attenuated by nicardipine, a calcium channel blocker. This indicates that extracellular calcium influx is required for contractile activation by ET-1. Interestingly, cardiac myocytes, which have been regarded as target cells of ET-1, are capable of synthesizing and secreting ET-1. This indicates that ET-1may act via an autocrine mechanism in the heart in some pathophysiological conditions.View full abstractDownload PDF (2636K) -
Tatsuo Yagura1994 Volume 13 Issue 2 Pages 113-119
Published: June 30, 1994
Released on J-STAGE: November 13, 2012
JOURNAL FREE ACCESSAutoantigen Ku is a DNA-binding protein complex composed of -80 kDa and -70kDa subunits. Although the role Ku complex plays in the cell nucleus remains unelucidated, an increasing number of studies have demonstrated that the Ku complex plays widespread functional roles in the cell, of which DNA repair and recombination, DNA replication, and transcription are proposed. Recent findings of proteins with sequence similarity to the human Ku complex and the association of Ku complex with DNAdependent protein kinase lead us to speculation on its role as a transcriptional regulator. Moreover, successful development of a monoclonal antibody cross-reactive to the Ku p70 subunit homologous to a wide variety of species has opened a novel functional role of the Ku complex in the establishment of nuclear structure.View full abstractDownload PDF (2549K)
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