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Biomedical subjects

R Imai

Publications and source records attributed to R Imai.

67 records · Page 4Linked to original sources
PubMed1980

Synthesis and biological activities of 7-alkoxymitosanes.

A facile alcoholysis of 7-methoxymitosanes and 5-methoxyindolequinone under basic conditions was discovered and a series of 7-alkoxymitosanes were synthesized from mitomycins A and B using this reaction. They showed strong antibacterial activity against various Gram-positive and Gram-negative bacteria and were potent inhibitors of cultivating HeLa S-3 cells in vitro. Among them, 7-n-propoxy-7-demethoxymitomycin A (2) showed the strongest antitumor activity against solid type Sarcoma-180 in mice.

Animals↗
PubMed1980

Antitumor activity of 7-N-phenyl derivatives of mitomycin C in the leukemia P388 system.

The antitumor activity of 7-N-phenyl derivatives of mitomycin C was tested in an ip-ip system of mouse leukemia P388 by single administration. The compounds tested were 7-N-phenyl-, 7-N-(p-aminophenyl)-, 7-N-(p-hydroxyphenyl)- and 7-N-(p-chlorophenyl)-mitomycin C. The maximum increases in life span (ILSmax) obtained were 124, 169, > 386 and 112%, respectively, that with mitomycin C being 104%. 7-N-(p-Hydroxyphenyl)-mitomycin C showed a higher ILS% than its ortho and meta isomers. Thus, 7-N-(p-hydroxyphenyl)-mitomycin C was the most effective of these compounds.

Animals↗
PubMed1977

The electrical induction of callus formation and external skeletal fixation using methyl methacrylate for delayed union of open tibial fracture with segmental loss.

A case of delayed union of an open tibial fracture with segmental loss is presented in which electricity was applied to the bone defect through two screws that were connected to a methy methacrylate skeletal fixation device. The fracture developed electrically induced callus formation around the cathode, callus extended to the anode, and solid bony union ensued. External skeletal fixation using methyl methacrylate is convenient and is a suitable adjunct to electrical stimulation of fracture healing.

Adult↗
PubMed1975

An experimental postoperative metastasis system using Yoshida sarcoma inoculated subcutaneously into footpad.

When Yoshida sarcoma cells were inoculated subcutaneously into the left footpad of Donryu rats, the weight of the left lumbar lymph nodes increased proportionally to the number of the inoculated cells. Resection of primary implants the day after the inoculation of 5 x 10(6) cells failed to rescue the host rats and they died of metastases within 12 days. There was no significant difference in mean survival days between the rats (8.9 days) whose primary implants were resected on the 5th day after inoculation and the control rats (8.6 days) bearing the primary implants. Mitomycin-C, a highly effective drug against Yoshida sarcoma cells, produced many long survivors (over 30 days) in the treated rats whose primary implants were resected the day after inoculation, but failed to do so when resected 5 days after inoculation. All of them died of metastases within 20 days. Based on these results, this present system is discussed for its usefulness as a screening and evaluation model for antitumor agents.

Animals↗
PubMedDate not supplied

Apocrine carcinoma vs. apocrine metaplasia with atypia of the breast. Use of aspiration biopsy cytology.

OBJECTIVE: To solve the problem of diagnosing apocrine carcinoma (APCA) through distinguishing it from benign apocrine metaplasia with atypia (APMA). STUDY DESIGN: The study group consisted of five histologically confirmed cases of uncommon infiltrating apocrine carcinoma and a case of noninfiltrating apocrine carcinoma of the breast by aspiration biopsy cytology. The control group consisted of 103 cases of benign apocrine metaplasia with no atypia (APMN), 4 cases of APMA and 34 cases of common-type adenocarcinoma that were encountered in 662 breast aspirations from 1988 to 1992 at Hekinan Municipal Hospital. RESULTS: In APCA the average age of patients (65 +/- 17.7 SD)(mean +/- SD) was more than 20 years older than APMA, and APCA generally measured > or = 2 cm or more in diameter as compared to < or = 2 cm in APMA lesions. In APCA the apocrine cells had high cellularity, with the cells occur singly and with syncytia in the background. Numerous degenerated apocrine cells and characteristic cell detritus were found. APCA was also characterized by apocrine cells with more marked nuclear abnormalities, including hyperchromasia and irregular nuclear shape, frequently with irregular nucleoli; more nuclei measure > or = 12 micron in diameter than in APMA. These findings, however, were present only to a mild degree in APMA, if at all. APMA may coexist with APCA. CONCLUSION: If APMA is diagnosed, an open biopsy should be performed to distinguish it from APCA.

Adult↗
PubMedDate not supplied

p53 protein expression and radiation-induced apoptosis in human tumors transplanted to nude mice.

Relationships between p53 protein expression and radiation-induced apoptosis in five human tumors transplanted to nude mice were studied immunohistochemically. They were irradiated with 200 kV X-rays. Six hours after 2, 5, 10, or 20 Gy irradiation, tumors were excised and fixed. Tumors were also examined 1-48 hours after 10 Gy. Immunohistochemical studies were performed for analysis of p53 protein expression. TUNEL and electron microscopic studies were performed to identify apoptosis. In non-irradiated control groups, the incidence of apoptosis was very low in all of the five tumors. Most tumor cells of the ependymoblastoma were p53 protein negative, but the other four tumors were p53 positive. Following irradiation, most tumor cells of the ependymoblastoma became p53 positive, and the incidence of apoptosis increased. However, we could not find significant changes in the percentage of p53 positive cells in the other tumors, and radiation-induced apoptosis in them was low or negligible. These results suggest that radiation-induced apoptosis in a radiosensitive human tumor is related to wild-type p53 protein expression. In contrast, the p53 protein expression of the other four human tumors should be mutant type, and it does not lead to radiation-induced apoptosis.

Animals↗