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T Ashihara

Publications and source records attributed to T Ashihara.

11 recordsLinked to original sources
PubMed1992

[Progress in microscopic image analysis and the trend of image cytometry].

Image cytometry has recently developed prominently based on the digital imaging of cell morphology brought about by great advances in microcomputer hardware and software, electronics etc. This method is characterized by the quantitation of both the amount of intracellular bioactive materials and cell morphology, and is expected to further advance many cell analysis techniques involving automated cytology, chromosome image analysis, automated histopathology, viable cell analysis, 3D image construction, etc. The present use is still minimal, and advances in both hardware and software for cyto-histologic recognition are essentially necessary. Perhaps by the end of this century, more sophisticated and faster machines for automated cyto-histologic analysis will appear, replacing many microscopic techniques of presently subjective observation in the biomedical field.

Cell Cycle↗
PubMed1992

[The usefulness of dipyridamole stress myocardial scintigram as a preoperative test for detecting ischemic heart disease before vascular surgery].

We evaluated the usefulness of dipyridamole 201Tl myocardial scintigraphy (DS) for detecting myocardial ischemia in 18 candidate for vascular surgery. DS indicated significant thallium redistribution in 6 patients. Coronary angiography was performed in 5 of these 6 patients and revealed significant coronary artery disease in all patients. As a result, operation was cancelled in 4 patients with severe coronary artery disease. One of these cases died of acute myocardial infarction after being discharged from hospital. One other patient was operated after percutaneous transluminal coronary angioplasty. Another patient was operated knowing that he had significant but mild coronary artery disease. Subsequently, operations were performed in 14 patients. No serious cardiac event occurred in these 14 patients except one case with T wave inversion without myocardial enzyme elevation. Thus, we concluded that DS was a useful method for detecting ischemic heart disease and prevent cardiac event associated with vascular surgery.

Aged↗
PubMed1992

[Analysis of cell proliferation kinetics and the effects of cisplatin on the cell cycle of human gastric cancer cells by autostage cytofluorometry].

Analysis of both cell proliferation kinetics and effects of cis-diamminedichloroplatinum (CDDP) on cell cycle in human gastric cancer cell line (HGC-Y2) by measuring the contents of nuclear DNA, RNA and the Ki-67 antigen using autostage cytofluorometry system was described. In HGC-Y2 cells, RNA content increased during the cell cycle and reached to the maximum at G2/M phase. The results of pulse treatment with CDDP on these cells demonstrated a prolongation of S phase and G2 arrest with increasing of RNA content of these cells. We classified the cells by intranuclear distribution pattern of Ki-67 antigen and thus could identified the cells at G0 and M phases from these classification. The content of Ki-67 antigen was moderate grade at G1 phase and it decreased in the early S phase, then increased gradually during S phase and at the late S phase. It increased rapidly, reaching to the maximum at G2/M phase. After CDDP treatment, the content of Ki-67 antigen increased in the cells in prolonged S phase and in the cells arrested at G2 phase. It was also found that the syntheses of both Ki-67 antigen and RNA were not inhibited by CDDP. These results suggest that the method using autostage cytofluorometry system was useful for the research, on the mechanism of cancer therapy because of making possible to analyze precisely the cell cycle and the influence of anticancer drugs.

Cell Cycle↗
PubMed1978

Constancy of the shift-up point in two temperature-sensitive mammalian cell lines that arrest in G1.

Two cell cycle-specific temperature sensitive (ts) mutants of mammalian cell lines, AF8 and K12, are known to arrest in G1 when shifted to the non-permissive temperature. We have determined the entry into S of both AF8 and K12 cells in five different growth conditions, namely: (1) quiescent sparse cultures stimulated to proliferative by serum; (2) quiescent dense cultures stimulated by serum; (3) quiescent sparse cultures stimulated by trypsinization and replating; (4) quiescent, dense cultures stimulated by trypsinization and replating; and (5) mitotic cells collected by mitotic detachment. In addition, for each cell line and for each different growth condition, we have determined the shift-up time, i.e., the time at which a shift-up to the nonpermissive temperature no longer prevents the entry of cells into S. In no case did K12 or AF8 enter S at the nonpermissive temperature. At the permissive temperature, the average time of entry into S varied in different growth conditions, and so did the shift-up time. However, in both cell lines, the distance of the average shift-up time from the average time of entry into S was remarkably constant, regardless of the growth conditions. i.e., 1.8 hours in K12 and 8.6 hours in AF8.

Cell Cycle↗
PubMed1978

Characterization of ts13 cells a temperature-sensitive mutant of the G1 phase of the cell cycle.

ts 13 cells are a temperature-sensitive (ts) mutant of BHK cells that are known to arrest in G1 when shifted to the nonpermissive temperature. We have determined the entry into S of ts13 cells in five different growth conditions, namely: 1) quiescent, sparse cultures stimulated to proliferate by serum. 2) Quiescent, dense cultures stimulated by serum. 3) Quiescent, sparse cultures stimulated by trypsinization and replating. 4) Quiescent, dense cultures stimulated by trypsinization and replating. 5) Mitotic cells collected by mitotic detachment. For each different growth condition we have also determined the execution point of the mutant function, i.e. the time at which a shift-up to the nonpermissive temperature no longer prevents the entry of cells into S. The median time of entry into S and the execution point varied in different growth conditions, but the distance between the median execution point and the median time of entry into S was remarkably constant, i.e. 3.2 hr. In addition we have fused ts 13 cells cells with chick erythrocytes and studied the ability of ts13 cells in heterokaryon formation to induce DNA synthesis in chick nuclei. Although ts13 cells can induce DNA synthesis in chick nuclei at the permissive temperature, they fail to do so when fused and stimulated at the nonpermissive temperature of 39.5 degrees C.

Animals↗
PubMed1978

A comparison of cell cycle-related changes in postmitotic and quiescent AF8 cells as measured by cytofluorometry after acridine orange staining.

AF8 cells were collected by mitotic detachment or made quiescent by serum restriction. Replated mitotic cells or serum-stimulated quiescent cells were then compared by flow cytofluorometry, when the use of acridine orange staining. Red fluorescence intensity (F greater than 600) was the same in quiescent cells and in cells immediately after mitosis. However, F greater than 600 increased very rapidly in postmitotic cells, while there was a delay in serum-stimulated quiescent cells. F greater than 600 reached a peak at 4 hr in postmitotic cells and between 16 and 19 hr in serum-stimulated quiescent cells. A similar delay in the time of entry into S phase occurred after serum stimulation of resting cell populations. The results are compatible with the hypothesis that cells after mitosis may enter a state that is different from the state of cells made quiescent by serum restriction.

Acridines↗
PubMed1976

3H-Thymidine labeled mast cells in mice treated with 20-methylcholanthrene: proliferation of precursor cells, their transformation into mast cells and migration of the latter.

In an attempt to clarify the kinetics of increase of mast cells, autoradiographic studies were performed on the mice which received a painting of 20-methylcholanthrene on the skin. In the first experiment, mice received 20-methylcholanthrene painting on their back for two, four and eight weeks. A fourty-eight hours' cumulative labeling with 3H-thymidine was performed directly before sacrifice. No labeled mast cells were found in the painted skin, despite a marked increase of mast cells in number. In the second experiment, mice received 20-methylcholanthrene painting for thirty-one days. A twenty-four hours' cumulative labeling was performed three, five, seven, fourteen, twenty-one and thirty-one days before sacrifice. A high labeling index of mast cells, up to 61.29%, was obtained in each group. When the time lapse between the time of cumulative labeling and the sacrifice is long, the labeling index is higher in the subcutaneous tissue, and when the time lapse is short, the labeling index is higher in the subepidermal tissue. From these results it was concluded that; 1) An increase of mast cells is due predominantly to the proliferation of precursor cells and their transformation into mast cells. 2) The proliferation of precursor cells occurs mainly in the subepidermal layer of the skin. 3) After the transformation, mast cells may migrate into the deeper layer of the skin.

Administration, Topical↗
PubMed1976

Analysis of incipient growth of Yoshida sarcoma in vivo after transplantation of a small number of tumor cells.

Incipient growth of Yoshida sarcoma in ascitic and solid forms was analyzed after transplantation of a small number of tumor cells varying from 1 to 10(6). Growth curves of the ascites tumors revealed that the duration of the incipient growth was much longer than the length of subsequent advanced stage and that the ascites tumor during its incipient stage appeared to grow exponentially and most rapidly in the entire course of the tumor development. Growth rate analyses of the ascites and solid tumors showed that, during their incipient stage, the population doubling time prolonged gradually as the inoculum size increased. This phenomenon was thought to suggest probable cell death on account of the transplantation procedure.

Animals↗