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Biomedical subjects

K Nagano

Publications and source records attributed to K Nagano.

At least 235 records · Page 13Linked to original sources
PubMed1983

Long-term in vivo carcinogenicity test of fish meal pyrolysate in Syrian golden hamsters.

The carcinogenicity of fish meal pyrolysate was examined in noninbred Syrian golden hamsters of both sexes. Hamsters were given a diet containing 5%, 10%, 20% or 40% fish meal pyrolysate for 102 weeks in Experiment 1, and 10% or 20% fish meal pyrolysate for 112 weeks in Experiment 2. Hamsters in control groups in both experiments were fed a normal basal diet. Various tumors were found in both experimental and corresponding control groups, but there was no significant difference in the incidence of any tumors between the experimental and control groups. Thus, the fish meal pyrolysate tested was not carcinogenic to Syrian golden hamsters under these conditions. In male hamsters the severity and incidence of fatty degeneration of the liver and chronic nephropathy tended to correlate with the concentration of fish meal pyrolysate in the diet. With females, however, the correlation was not so clear. In neither sex did the presence of atrial thrombosis or systemic amyloidosis appear to be dependent on the dietary concentration of fish meal pyrolysate.

Amyloidosis↗
PubMed1982

Formation of amino acids from models of Titan and more oxidized atmospheres.

Protein and non-protein amino acids were synthesized following hydrolysis of products obtained by high frequency discharge techniques applied to model atmospheres consisting of N2 as a nitrogen source together with CH4 and/or CO2 as a carbon source. Highest yields were obtained in the absence of CO2 and from mixtures rich in CH4. Amino acids would indeed be expected on the frozen surface of Titan with its CH4-N2 atmosphere.

Amino Acids↗
PubMed1982

Molecular arrangement of troponin-tropomyosin in the thin filament.

Clarification of molecular arrangement of three troponin components in the thin filament is one of the essential problems in the field of the calcium regulation of muscle contraction. This review aims at discussing the present status of our structural studies of these Ca receptive proteins. Particular attention was rapid to the role of troponin T which connects troponin complex to tropomyosin. Studies on the paracrystalline structure indicated that the size of troponin complex is an order of 10 nm and the whole axial length is determined by the rod shaped troponin T molecule. The molecular arrangement of each component studied by immuno electron microscopy, indicated that troponin C, troponin I, and C-terminal region of troponin T (troponin T2) are exposed on the surface of thin filament to the similar extent. The N-terminal subfragment of troponin T, troponin T1, on the other hand, was shown to be mostly embedded in the depth of the complex and only exposed to the direction of Z-line in the thin filament. It was further attempted to connect these structural finding with the primary amino acid sequence. Since the classical crystallographic results have not yet been obtained, we instead introduced the prediction technique for the secondary and supersecondary structures from the known amino acid sequences. The interacting structure of troponin T-tropomyosin was analyzed especially in detail. It was thus concluded that the T1 region of troponin T strongly binds to tropomyosin by forming triple stranded coiled-coil structure. One plausible model of troponin components and tropomyosin constructed at amino acid level was also presented.

Amino Acid Sequence↗
PubMed1982

Duality of alpha-subunit of canine kidney sodium- and potassium-activated adenosinetriphophatase in electrophoresis.

Sodium- and potassium-activated adenosinetriphosphatase (Na+, K+-ATPase) purified from dog kidney outer medulla was examined by polyacrylamide gel electrophoresis and by photoaffinity labeling with N-(ouabain)-N'-(2-nitro-4-azidophenyl)-ethylenediamine (NAP-ouabain). The large subunit band (alpha-band) split into two bands on the gel after the enzyme was heat-treated in the presence of 1% sodium dodecylsulfate (SDS). Of the two bands (alpha I and alpha II), alpha I had the same electrophoretic mobility as the original band, while alpha II moved slightly faster. Total conversion into alpha II was not observed, about half of the original remaining as alpha I. Below 60 degree C, heat treatment did not produce alpha II. Phenylmethylsulfonyl fluoride did not prevent the appearance of alpha II. Both alpha I and alpha II were labeled with [3H]NAP-ouabain. Nonspecific incorporation of [3H]NAP-ouabain also occurred irrespective of illumination, but it was removed either by diffusion during staining and destaining of the gel or by treatment of the enzyme with trichloroacetic acid. It is tentatively concluded that the splitting of the band reflects some intrinsic differences in situ of the alpha-subunit of dog kidney membrane Na+,K+-ATPase.

Affinity Labels↗
PubMed1982

Vascular tumors of the spleen and other neoplasms induced in Syrian golden hamsters by 1-propyl-1-nitrosourea.

Continuous administration of either 400 ppm or 100 ppm 1-propyl-1-nitrosourea (PNU) in drinking water to Syrian golden hamsters, from 11 weeks of age, induced tumors of the spleen, forestomach, duodenum, and vagina. The tumor incidences in the spleen were 33 of the 36 males (91.7%) and 34 of the 37 females (91.9%) in the 400 ppm group and 32 of the 40 males (80%) and 26 of the 34 females (76.5%) in the 100 ppm group. In addition, tumors were induced in the forestomach and duodenum of both sexes and in the vagina in females. Histologically, the tumors were classified as hemangioendotheliomas of the spleen, squamous cell papillomas and carcinomas of the forestomach, adenocarcinomas of the duodenum, and squamous cell papillomas and carcinomas of the vagina. Compared to results previously reported in rats, the present results reveal a remarkable species difference in the organ specificity of PNU.

Adenocarcinoma↗
PubMed1981

Embryotoxic effects of ethylene glycol monomethyl ether in mice.

An embryotoxicity study on ethylene glycol monomethyl ether (EGM) was carried out in ICR mice. They were given EGM daily at 6 dose levels (31.25, 62.5, 125, 250, 500 or 1000 mg/kg body wt) by gastric intubation on days 7 through 14 of gestation. On day 18 of gestation all fetuses were examined. Marked and dose-related embryotoxic effects were observed. Skeletal and gross anomalies, reduced fetal weight and fetal death were all observed at lower dosages of EGM, while marked leucopenia of the dams occurred at the highest dose.

Abnormalities, Drug-Induced↗