Kohzaburo Fujikawa‐Yamamoto

Kanazawa Medical University

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H Yamagishi

Kanazawa Medical University

Minoru Miyagoshi

Kanazawa Medical University

Shizuo Odashima

Kanazawa Medical University

Zhi-ping Zong

First Affiliated Hospital of Guangzhou Medical University

Manabu Murakami

Hokkaido University

Mikio Tanino

Kanazawa Medical University

Kenji Kawamura

Kibi International University

Manabu Moriyama

Kanazawa Medical University

Takayuki Nojima

Kanazawa Medical University

Nobuo Yamaguchi

Nagasaki University

Cooperative Institutions

Kanazawa Medical University

Kanazawa University

Hokkaido University

University of Cincinnati Medical Center

Kanazawa Medical University Hospital

Hiroshima University

Osaka University

Chiba University

Kyushu University

Chinese Academy of Medical Sciences & Peking Union Medical College

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Different Manner of DNA Synthesis in Polyploidizations of Meth-A and B16F10 Cell Lines.

Cell Structure and Function (1997)

Kohzaburo Fujikawa‐Yamamoto Zhi-ping Zong Manabu Murakami Shizuo Odashima

Polyploidization of Meth-A and B16-F10 cells by demecolcine was examined using flow cytometry (FCM). In the presence of demecolcine, both cell lines were polyploidized to more than 16c DNA content. A marked difference was observed in the durations of S phase of polyploidy. The S-phase duration of Meth-A cells was doubly increased with ploidy, but that of B16F10 cells remained constant. When the rate of DNA synthesis in the polyploidizing cells was examined through the BrdU-uptake experiments, it was confirmed that the level of DNA-synthesis rate was constant in Meth-A cells but increased in B16F10 cells. The cellular content of c-Myc protein in polyploidized cells was also examined using anti-c-Myc monoclonal antibody. The c-Myc level of Meth-A cells was constant regardless of the ploidy but that of B16F10 cells increased with ploidy. Thus, the c-Myc content seems to be related to the duration of S phase in polyploidy.

Meth-

10.1247/csf.22.527

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Citations (9)

Synergistic effects of hydroxyurea and thymidine on the growth inhibition of V79 cells.

Cell Structure and Function (1989)

Kohzaburo Fujikawa‐Yamamoto Shizuo Odashima

The effects of hydroxyurea (HU) and thymidine (TdR) on cell cycle progression in V79 Chinese hamster lung cells were examined by flow cytometry. Suppression of the cell cycle progress rate by HU was further enhanced by the combination of a low concentration of TdR and HU as com-pared to that induced by TdR alone; i.e., these drugs were shown to have a synergistic effect. It was concluded that the presence of TdR was effective in assisting HU-induced suppression of DNA synthesis.

Chinese hamster

Thymidine

Hydroxycarbamide

10.1247/csf.14.399

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Citations (1)

Rna dependence in the cell cycle of V79 cells

Journal of Cellular Physiology (1982)

Kohzaburo Fujikawa‐Yamamoto

Abstract The cell cycle of V79 Chinese hamster lung cells synchronized by hydroxyurea was investigated by flow cytometry. The metachromatic fluorochrome acridine orange was used to differentially stain DNA and RNA of V79 cells. Green and red fluorescence from individual cells, representing cellular DNA and RNA, respectively, was measured by flow cytometry. Periodic changes of cellular DNA and RNA contents were observed over nine cell cycles. The duration of G 1 , S, and G 2 + M phases of synchronized V79 cells whose RNA content was close to that of the cells in balanced growth was 3, 4.5, and 1.5 hours, respectively. The duration of G 1 and S phases of cells containing RNA above a certain threshold was inversely proportional to the RNA content. The RNA content of cells containing RNA above the normal level regressed to normal after a few generations. Coefficients of variation for RNA content were significantly larger than those for DNA. An explanation for the decay of synchrony in a synchronized cell population is proposed.

10.1002/jcp.1041120110

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Citations (34)

Effects of hydroxyurea on the phagocytosis of microspheres in V79 cells.

Cell Structure and Function (1989)

Kohzaburo Fujikawa‐Yamamoto Shizuo Odashima

Phagocytosis of fluorescent microspheres in V79 cells arrested in the S phase by hydroxyurea (HU) was investigated by flow cytometry. The phagocytic activity increased with the exposure time of HU. No dependency on the HU concentration was observed in the concentration used. Cell size (projec-tion area) and membrane fluidity, two factors effected by HU treatment, were examined in relation to phagocytic activity, and were found to be significantly increased. The elevation in phagocytic activity could be interpreted in terms of the alteration in the two physiological factors.

10.1247/csf.14.485

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Citations (2)

Hyperploidlzation of V79 Cells by K-252a in Comparison with Demecolcine.

Cell Structure and Function (1993)

Kohzaburo Fujikawa‐Yamamoto Kouhei Teraoka Shizuo Odashima

The cellular responses of the V79 cell cycle to K-252a, a protein kinase inhibitor, were examined by flow cytometry (FCM) and by time-lapse videomicrography. At a concentration of 0.5 μM of K-252a for 72 h, V79 cells became hyperploid, having above 32c DNA content. The cycle times in the hyperploidizing process were 11.2 (4c-8c), 16.3 (8c-16c) and 19.3 (16c-32c) hours, values which were less than twice that of the control (10.5 h). After the washout of K-252a, the DNA content was widely distributed in the V79 cell population and hyperploid V79 cells reduced DNA content through a variety of cell division modes. These cellular responses to hyperploidization of V79 cells by K-252a were in reasonable agreement with those by demecolcine.

10.1247/csf.18.449

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Citations (15)

CYTOLOGIA (2005)

Kohzaburo Fujikawa‐Yamamoto Minoru Miyagoshi H Yamagishi

The DNA content of polyploid cells sometimes decreases during subculturing. The mechanism of DNA reduction is not yet known. Precise measurements of DNA decay and related alterations in polyploid cells will be required to understand the mechanism. Diploid, tetraploid and octaploid Meth-A cells were continuously cultured for 244 d and the cellular DNA content was measured from the DNA histograms. The DNA content decays gradually with day t as expressed by f(t)=Ip exp{−G(t)}, where Ip is the initial ploidy, G(t)=at/{exp(−bt)+ct}, and a, b and c are the following parameters: a=0.026, b=0.01 and c=0.0175 (for tetraploid cells) or c=0.01 (for octaploid cells). The DNA content of diploid Meth-A cells was constant within the experimental errors. The DNA loss of polyploid cells was confirmed by a decrease in chromosome number. The cellular morphology changed in diploid and octaploid Meth-A cells, but not in tetraploid cells, suggesting that DNA loss and morphology alteration are independent. The doubling time shortened with culture time in the tetraploid and octaploid cells. The findings suggested that chromosomes are not independent in polyploid cells.

Polyploid

Chromosome number

10.1508/cytologia.70.337

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The Establishment of Tetraploid Human Embryonic Cells Using Demecolcine

CYTOLOGIA (2013)

Minoru Miyagoshi Kohzaburo Fujikawa‐Yamamoto H Yamagishi

Diploid human embryonic cells were exposed to demecolcine for 3 d and then released from this exposure. At that time, the cell population was a mixture of diploid and tetraploid cells. Tetraploid cells were obtained through the cloning of this mixture of cells. The doubling time of the tetraploid cells was 16 h, identical to that of the diploid cells. The tetraploid cells had 92 chromosomes and double the DNA content of the parent diploid cells. The cell volume of the tetraploid cells was about twice that of the diploid cells. The duration of the G1, S, and G2/M phases was almost the same as for diploid cells. It was concluded that the established tetraploid human embryonic cells have cellular characteristics similar to those of diploid human embryonic cells.

Cloning (programming)

WI-38

10.1508/cytologia.78.417

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Lack of synchrony among multiple nuclei induces partial DNA fragmentation in V79 cells polyploidized by demecolcine

Cell Proliferation (1999)

Kohzaburo Fujikawa‐Yamamoto Chie Ohdoi H Yamagishi Zhi-ping Zong Manabu Murakami

Abstract. The nuclear morphology of polyploidized cells was examined in V79 Chinese hamster cells polyploidized by demecolcine or K‐252a, inhibitors of spindle fibre formation and protein kinases, respectively. A variety of nuclear morphologies, including multinuclei, were observed in V79 cells polyploidized by demecolcine but not by K‐252a, which produced mononuclear cells. A lack of synchrony in the nuclear cycle was observed among nuclei in multinuclear polyploidized cells. Partial DNA fragmentation, defined as DNA fragmentation of a nucleus in a multinuclear cell, was detected using the TUNEL method in V79 cells polyploidized by demecolcine but not by K‐252a. Apoptosis occurred earlier in cell populations treated with demecolcine than in these treated with K‐252a once the drugs were removed from the medium, suggesting that polyploidized cells with separate nuclei tend to apoptose earlier than those with mononuclei.

Fragmentation

Chinese hamster

10.1111/j.1365-2184.1999.tb01352.x

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Citations (8)

Centrosome Hyperamplification and Chromosomal Instability in Bladder Cancer

European Urology (2003)

Kenji Kawamura Manabu Moriyama N. Shiba Mamoru Ozaki Takuji Tanaka

Chromosome instability

10.1016/s0302-2838(03)00056-3

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Citations (32)