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Biomedical subjects

M Nakada

Publications and source records attributed to M Nakada.

At least 91 records · Page 5Linked to original sources
PubMed1983

[Immunological competence of nude mice on the growth of transplantable human tumors--with reference to natural killer cells].

Influences of natural killer cells on the transplantable human tumors was evaluated by using anti-asialo GM1 antibody. Two human gastric adenocarcinomas designated as St-4 (poorly differentiated) and St-40 (well differentiated) were inoculated into nude mice. The effects of anti-asialo GM1 antibody were assessed in terms of tumor doubling time (Td) and 3H-thymidine (3H-TdR) uptake labeling index (L.I.). Whereas the Td of St-4 was significantly shortened by administration of anti-asialo GM1 antibody, no noticeable changes were observed in St-40. This enhanced growth of St-4 was also supported by the elevation of L.I. both in flashing and repeating methods. On the other hand, as the repeated L.I. of St-40 was almost 100% in control tumors, repeated L.I. was not increased by the administration of anti-asialo GM1 antibody. It was supported that natural killer activity of nude mice regulated the growth of transplantable human tumors concerning with the growth fractions.

Adenocarcinoma↗
PubMed1983

Antitumor effect and metabolic activation of cyclophosphamide and 4-hydroperoxycyclophosphamide in the human breast carcinoma (MX-1)-nude mouse system.

The effects of cyclophosphamide (CPA) and its active form, 4-hydroperoxy-CPA, against human breast carcinoma transplanted into nude mice (BALB/c nu/nu) were evaluated in terms of the decreases of hepatic drug-metabolizing enzymes in nude mice. A human breast carcinoma, MX-1, was implanted into the subcutaneous tissue of nude mice and a drug was administered intravenously once at a dose of 0.05, 0.1 or 0.15 mmol/kg, 1 or 3 weeks after tumor inoculation. 4-Hydroperoxy-CPA was more effective than CPA as regards inhibition of tumor growth, and the difference in effect was greater when the drugs were administered 3 weeks after tumor inoculation. The activity of CPA was depressed by the decrease of the hepatic drug-metabolizing enzymes in proportion to the tumor-bearing period. Therefore, the effects of masked derivatives of CPA may correlate with the changes in drug-metabolizing activities of tumor-bearing mice. The human tumor xenografts-nude mice system is considered to be suitable for chemosensitivity tests with masked compounds.

Adult↗
PubMed1982

[Effect of mitomycin C on human gastric and colon carcinomas serially transplanted to nude mice--with special reference to the start of drug administration].

Three human gastric carcinomas and one colon carcinoma serially transplanted to nude mice were used for experimental chemotherapy of mitomycin C (MMC) with special reference to the start of drug administration. BALB/c nu/nu male originated from the Central Institute for Experimental Animals were used. All the experiments were carried out under the specific pathogen-free conditions using laminar air flow racks. Tumors used for experiments were St-4; poorly differentiated adenocarcinoma of stomach, St-15; mucinous adenocarcinoma of stomach, KS-1; poorly differentiated adenocarcinoma of colon. MMC at the doses of 2 or 3 mg/kg were administered intraperiatoneally once a week for 3 or 4 times starting from 24 hours (DAY-1 Adm.) or 2 weeks (DAY-14 Adm.) after tumor inoculation. Response to chemotherapy was evaluated on the basis of growth curves, tumor weights, and histopathological changes. Whereas St-15, a sensitive strain to MMC, was suppressed by DAY-1 and DAY-14 administration. Similarly, DAY-1 administration revealed more excellent effect on the other three tumors than DAY-14 administration. These results indicated that MMC was more effective when the tumor mass was smaller, and also suggested that the adjuvant chemotherapy of surgical operation should be started as soon as possible after tumor resection or reduction. In the case of DAY-1 treatment, the false positive result by anti-vascularization effect of MMC could not be excluded, it seems to be adequate that drug administration should be started after the initiation of logarithmic growth phase of the tumors.

Animals↗
PubMed1982

[Microvascular architecture of human tumors transplanted in nude mice--its relationship to sensitivity to antineoplastic agents].

Microangiographic study was performed with ten human tumors serially transplanted into nude mice to clarify the role of tumor vessels on the chemosensitivity of the human tumors. Five gastric carcinomas, two colon carcinomas, one breast carcinoma, one cholangiocarcinoma, and one hemangiopericytoma were used for the experiments. Seven tumors revealed hypervascular network of vessels, whereas hypovascular patterns of tumor vessels were observed in the other three tumors. It was found that the histologically differentiated tumors were hypervascular and undifferentiated tumors were hypovascular, with statistically significant differences (p less than 0.05). Each tumor possessed the vascular network similar to human tumors originated from the same organs. No discernible changes of microangiographic features were noticed by serial transfers. As the chemosensitivities of these tumors depended mainly on their original tissues, these chemosensitivities could not be explained only by tumor vascularities or drug transferences. However, in the tumors with similar chemosensitive spectra, less susceptible tumors were observed to possess the irregular vascular networks in comparison with sensitive strains. From these considerations, tumor vessels were thought to have some role on vascular flow and drug transference which affected chemosensitivity of human tumors.

Animals↗