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Biomedical subjects

Y Hirokawa

Publications and source records attributed to Y Hirokawa.

At least 91 records · Page 5Linked to original sources
PubMed1987

Antitumor activity of trienomycin A on murine tumors.

The antitumor activity of a novel ansamycin antibiotic, trienomycin A, against various murine tumors was studied with two treatment schedules. The intraperitoneal injection of the antibiotic showed remarkable antitumor activity on sarcoma 180 and P388 leukemia at doses of 160 or 320 mg/kg, showing 151% and 100% increase in life span, respectively. Trienomycin A inhibited the growth of Ehrlich and Meth A cells in vitro at doses of 0.1-0.4 microgram/ml when the cells were exposed to the antibiotic for 72 hours. The incorporation of [3H]thymidine into acid precipitable material in HeLa cells was slightly more marked than that of [3H]uridine and [3H]leucine when the cells were exposed to 0.04 or 0.08 microgram/ml of trienomycin A for 4 hours. It appeared that trienomycin A showed antitumor activity by direct cytotoxic action.

Alanine↗
PubMed1986

[The suppressive effect of pyrrole-2-carboxylic acid on platelet aggregation].

In the course of a search for novel antibiotics, an antiplatelet substance was isolated from the fermentation broth of Streptomyces sp. No. 82-85. Thereafter, the active substance was identified as pyrrole-2-carboxylic acid (P2C) by structural studies. The effects of P2C on adenosine diphosphate (ADP)-, arachidonic acid-, collagen- or tumor cell-induced platelet aggregation were examined in vitro and ex vivo. In in vitro studies, P2C (25-100 micrograms/ml) suppressed the aggregation of platelets of normal Wistar rats. The intraperitoneal administration of P2C (200 mg/kg) to rats and rabbits suppressed platelet aggregation induced by ADP, arachidonic acid and collagen when examined for 0.5-3 hours after administration. The agent also suppressed platelet aggregation induced by both mouse syngenic tumors, Meth-A fibrosarcoma and IMC carcinoma in vitro.

Adenosine Diphosphate↗
PubMed1985

Antitumor activity of a new antibiotic, kazusamycin.

The antitumor activity of a new antibiotic, kazusamycin, against various murine tumors was studied by various treatment schedules. Single, intermittent, and successive injections of the antibiotic were almost equally effective against Ehrlich carcinoma, IMC carcinoma and sarcoma 180 tumor, but successive injections showed more efficacy than the other schedules against Meth A fibrosarcoma and Lewis lung carcinoma. Interestingly, there was no clear dose response for the efficacy of kazusamycin on murine tumors. When HeLa cells were exposed to kazusamycin for 72 hours in vitro, the IC50 value was about 1 ng/ml, however the cytotoxicity of the antibiotic depended on the incubation time.

Animals↗
PubMed1985

[Postoperative radiotherapy for carcinoma of the uterine cervix].

During the period between 1972 and 1978, 226 patients were operated on for carcinoma of the uterine cervix at Hiroshima University, and 91 patients were treated by postoperative external irradiation. Patients with lymph node metastasis showed markedly lower five-year survival rates stage I: 44.4%; stage II: 45.0%) than those without lymph node metastasis (99.3% and 84.0%, respectively). In view of benefits of postoperative radiotherapy in the treatment of cervical cancer, only to the node positive and tumor rest patients is recommended.

Combined Modality Therapy↗
PubMed1983

Usefulness of two-dimensional echocardiography for diagnosis of the sites of origin in myxoma.

Three patients with atrial myxoma, two in the left atrium and one in the right were studied using two-dimensional echocardiography. An analysis by four cross sections, long and short axis, subcostal and four chamber views of the left ventricle showed that the stalk of one left atrial myxoma adhered to the anterior commissure, the other to the left atrial wall underlying on the aortic posterior wall, and that of right myxoma to the free wall of the right atrium. The myxomas were successfully removed by surgical intervention in all cases, where the sites of stalk were verified to be identical with those diagnosed by echocardiography.

Adult↗
PubMed1980

81mKr gas generator for lung ventilation study.

A generator of 81mKr was designed and tested. The parent nuclide 81Rb was produced by the 70 MeV proton induced reactions on a Rb2SO4 target. 81mKr was bubbled out with oxygen gas from the 81Rb solution, and collected in a reservoir for lung ventilation studies. The generator was continuously operated at the high flow rate up to 10 1/min. The generator efficiency was 86%. The collection rates in the reservoir were examined under several flow rates. The pure 81mKr isomer was observed wih a NaI (T1) detector at the reservoir.

Humans↗
PubMed1974

Endogenous C-type virus of a mouse cell line and its defectiveness.

MLg cells originating from a newborn ddY mouse began to release C-type virus by treatment with 5-iodo-2'-deoxyuridine (5 mug/ml) for 48 h, or spontaneoulsy after prolonged cultivation. The data indicated the presence of three categories of the viruses spontaneously induced, i.e., virus equipped with the abilities of infecting and transforming the S+L- C182 cells, virus which can infect C182 cells but is unable to transform C182 cells, and virus which cannot infect nor transform the C182 cells, but is positive for the XC test. The type of the virus produced depended upon the cell clone. With the advance in the passage level, the cell population was dominated by the cells producing, uniquely, the last category of the virus.

Animals↗