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Biomedical subjects

K Takemoto

Publications and source records attributed to K Takemoto.

At least 145 records · Page 8Linked to original sources
PubMed1981

[Cranial computed tomography of the neurofibromatosis (author's transl)].

The computed tomography (CT) was performed in 10 cases of neurofibromatosis. The CT scan showed the abnormal findings in 8 cases out of 10. Skull lesions were noted in 3 cases and intracranial tumors were found in 5 among which multiple neoplasms were seen in 3. Although reported cases were not large enough in number, the incidence and variety of the tumors were similar to others reported before CT era.

Adolescent↗
PubMed1981

Carcinogenicity of benzyl chloride, benzal chloride, benzotrichloride and benzoyl chloride in mice by skin application.

The carcinogenicity of benzyl chloride (BYC), benzal chloride (BAC), benzotrichloride (BTC) and benzoyl chloride (BOC), which were suspected as causative agents of lung cancer and maxillary malignant lymphoma of workers employed in factories producing BOC, was examined by skin applications in female ICR mice. After rather high dose exposure, BTC exhibited leukemogenic and pulmonary tumorigenic activities as well as potent dermal carcinogenic activity. After administration of the chemicals at the dose of 2.3 microliter/animal, twice a week for 50 weeks, BTC induced 68% incidence of skin cancers and 58% incidence of pulmonary tumors (including 10% of lung carcinomas) within 399 days. Incidence of skin cancers was 58% for BAC, 15% for BYC and 10% for BOC within 560 days. Considering the extent of possible exposure of the workers to these chemicals in the working environment and the carcinogenic potency of the chemicals tested, it can be concluded that BTC was very probably responsible for causing the cancers seen int he workers employed in manufacturing BOC.

Animals↗
PubMed1980

Sequential computed tomography scans in acute cerebral infarction.

Sequential computed tomography (CT) scans were obtained in 30 patients with acute cerebral infarction. In some cases, infarction was seen on the scans as early as three to six hours after onset of symptoms. Although small areas of petechial hemorrhagic infarction are not easily detected by currently available equipment, positive contrast enhancement helps locate petechial hemorrhagic infarction, which is usually in the cortical gray matter of the cerebral mantle and the central gray matter of the deep central gray matter. Contrast-enhanced CT scans are a useful method for detecting small infarctions. However, when a CT scan is performed within five days of ictus, contrast enhancement is usually not required.

Acute Disease↗
PubMed1980

Role of uridine phosphorylase for antitumor activity of 5'-deoxy-5-fluorouridine.

5'-Deoxy-5-fluorouridine (5'-DFUR) was parenterally and orally effective on various transplantable tumors and its activity was better than that of other fluorinated pyrimidines. However, like 5-fluorouracil and 2'-deoxy-5-fluorouridine (FUdR), 5'-DFUR was ineffective on L1210 leukemia resistant to 5-fluorouracil, suggesting that it would exert its antitumor activity through converted 5-fluorouracil. In tissue culture, 5'-DFUR inhibited the growth of various tumor cells similarly to ther fluorinated pyrimidines. However, 5'-DFUR was unique in that uridine completely reversed its inhibitory effect. Enzymological study clarified that uridine inhibited the conversion of 5'-DFUR to 5-fluorouracil by a uridine phosphorylase, in parallel to its reverse effect on cell growth inhibition by 5'-DFUR. Furthermore, a subline of L1210 leukemia resistant to 5'-DFUR but not to 5-fluorouracil was found to lack the uridine phosphorylase. These results indicate that 5'-DFUR is a depot form of 5-fluorouracil which can be promptly activated by uridine phosphorylase. In addition, the uridine phosphorylase was found to be abundant in sarcoma-180 solid tumor, leading to a significantly higher concentration of converted 5-fluorouracil in this tumor than in other normal tissues. This provides a good explanation for the high chemotherapeutic index of 5'-DFUR against this tumor, which may be applicable also for other tumors.

Animals↗
PubMed1980

Comparative studies on the immunosuppressive effect among 5'-deoxy-5-fluorouridine, ftorafur, and 5-fluorouracil.

The immunosuppressive effect of 5'-deoxy-5-fluorouridine (5'-DFUR, Ro 21-9738) was examined for both humoral and cell-mediated immunity in mice in comparison with that of 5-fluorouracil and Ftorafur (FT-207). By both oral and intraperitoneal administration, 5'-DFUR was found to be much less suppressive than 5-fluorouracil and FT-207 in all immune responses tested; hemolysin plaque-forming cells, serum hemolysin titer, delayed-type hypersensitivity and allogeneic tumor rejection. Furthermore, 5'-DFUR did not induce any reduction in either the spleen weight, thymus weight, total spleen cell number, or peripheral leucocyte number.

Animals↗
PubMed1979

Photochemical reactions on the synthetic polymers containing thymine bases.

Photodimerizations of N-2-isobutyloxyethyl thymine (T-M), bis[2-(5-methyl-1-pyrimidinyl)ethyl]glutarate (T-T), poly-N-2-methacryloyloxethyl thymine (P-MAOT) and poly-N-2-acryloyloxyethyl thymine (P-AOT) were studied in dimethylformamide solution. Quantum efficiencies of intramolecular photodimerizations were determined to be 0.0012 for T-T, 0.0084 for P-MAOT and 0.010 for P-AOT. In the case of T-M, however, intermolecular photodimerization did not occur under the reaction condition used. Quenching studies by using isoprene suggest that the photodimerization of T-T occurs predominantly through an excited triplet state, while that of P-MAOT and P-AOT occur through both singlet and triplet states. For the effect of adding model compounds containing adenine bases on this reaction, adenine derivatives acts as an inhibitor against this reaction by quenching the excited singlet state of thymine. The photodimers of T-T, P-MAOT and P-AOT were concluded to be two syn-fused cyclobutane- type dimers (cis-syn and trans-syn).

Photochemistry↗