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Biomedical subjects

K Nishio

Publications and source records attributed to K Nishio.

At least 235 records · Page 13Linked to original sources
PubMed1987

Screening for carcinogens by the DNA synthesis inhibition test using human fibroblasts.

The Ames test has probably been the most common prescreening test for potential carcinogens. This system, however, occasionally presents false-positive or false-negative results for certain kinds of chemicals. We chose 24 agents, most of which showed a discrepancy in their results with the animal carcinogenicity test and the Ames test, and screened them by the DNA synthesis inhibition test using human fibroblasts. Among 22 agents, 13 (59%) showed consistent results, 6 (27%) showed discrepant results with those obtained by animal tests and 3 (14%) showed ambiguous results. The majority of the DNA synthesis inhibition test results for these chemicals were consistent with the results obtained by whole animal tests, suggesting that the DNA synthesis inhibition test with mammalian cells in culture is a reasonably reliable prescreening test for potential carcinogens.

Animals↗
PubMed1987

[Adult T-cell leukemia--from retrovirus-induced T-cell leukemia in dermatologic patients. Clinical histologic and epidemiologic studies].

In 1976, adult T-cell leukemia (ATL) was reported as a special form of T-cell leukemia. In such cases the following criteria are prominent: strong inclination to leukemic change, incidence of abnormal cells in the peripheral blood, and the existence of an endemic area at the time of the outbreak of the disease. The abnormal tissue infiltrating ATL cells originate from peripheral blood T-lymphocytes, and in these lymphocytes the causal retrovirus HTLV-I could be proven. Since pathognomonic cutaneous manifestations can be observed among almost 50% of the patients, knowledge of this disease is of great importance to dermatologists. Two cases are reported focussing on the clinical and histopathologic findings concerning the cutaneous manifestations. Epidemiologically, up to 1984, we collected and analyzed 153 Japanese cases. There is a minor difference in sex distribution, but the incidence of ATL is highest among people in their fifties. The region of Kyushu, especially the southwestern part, and of Okinawa proved to be the endemic centers of ATL.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1986

[DNA synthesis inhibition test of INAH by cultured human fibroblasts].

The most commonly used screening test of carcinogens is the Ames test. But this system occasionally shows false positive and false negative. Painter's method is one which has been developed to minimize false results. Now we test by Painter's method isonicotinic acid hydrazide, which shows negative in the Ames test but positive in an animal test. INAH showed positive by Painter's method. More chemicals are now under study for their carcinogenicity by Painter's method.

DNA↗
PubMed1985

Subunit structure and tRNA-binding properties of Bombyx mori Glycyl-tRNA synthetase.

Large amounts of glycyl-tRNA synthetase were purified from the posterior silk glands of Bombyx mori. The synthetase was estimated to be a dimer with a molecular weight of 180,000. When the enzyme solution was diluted, the dimer dissociated into monomers which were inactive in tRNA aminoacylation. The aminoacylation was investigated with two isoaccepting tRNAsGly isolated from the posterior silk glands. Transfer RNA1Gly was aminoacylated 2-fold faster than tRNA2Gly. Transfer RNA-binding experiments revealed that tRNA1Gly binds with the enzyme in a molar ratio of 2:1, whereas tRNA2Gly formed a 1:1 complex with the enzyme. Based on these experimental results, we proposed that the Bombyx mori glycyl-tRNA synthetase has two active sites for tRNA aminoacylation and that the number of tRNA molecules bound on the synthetase closely correlates with the velocity of aminoacylation.

Amino Acyl-tRNA Synthetases↗
PubMed1984

Purification and properties of alanyl-tRNA synthetase from Bombyx mori: a monomeric enzyme.

Alanyl-tRNA synthetase was purified from the posterior silk glands of Bombyx mori by ammonium sulfate fractionation and chromatography on DEAE-Sephacel and hydroxyapatite columns. The yield was about 100 mg of the enzyme per 1 kg of the glands. The enzyme required both L-alanine and alanine tRNA for pyrophosphate formation from ATP. The PPi formation was observed even after tRNA was fully aminoacylated. The enzyme was found to be a monomer of 115K daltons by SDS-polyacrylamide gel electrophoresis, gel filtration and suberimidate cross-linking experiments. The monomeric enzyme did not dimerize in the presence of the alanine tRNA. The enzyme and the tRNA formed a 1:1 complex. The results indicate that Bombyx mori alanyl-tRNA synthetase functions in a monomeric state.

Alanine-tRNA Ligase↗
PubMed1984

The effect of changing the maxillomandibular relationship by a bite plane on the habitual mandibular opening and closing movement.

The relationship between the change of afferent information from occlusal contacts and its influence on the jaw muscles was investigated. For this purpose, the following questions were posed and experimental studies designed. If the subject was given habitual occlusal contacts in centric relations with a bite plane, were the habitual mandibular closing and opening movements influenced? Second, was it easier for the subjects to accomplish regular habitual mandibular opening and closing movements, when the bite plane was inserted and removed? From the results it could be concluded that the centric occlusal contacts in centric relation were more physiological for the jaw muscles. In addition, when the new occlusal position was coincident or close to the centric relation, it was easier for the subject to study and acquire the new habitual mandibular opening and closing movement.

Adolescent↗
PubMed1984

Two-domain structure of alanyl-tRNA synthetase from Bombyx mori: isolation of the N-terminal catalytic domain.

Alanyl-tRNA synthetase of 115K daltons from Bombyx mori was cleaved into two fragments of 62K and 47K daltons by trypsin. The 47K fragment was active in aminoacylation of tRNA, whereas the 62K fragment was inactive. The 47K and 62K fragments were found to be located at the N- and C-terminal ends, respectively, in the intact enzyme. The intact enzyme was protected from trypsin-attack by the cognate tRNA. The Km value of the 47K fragment for tRNA was 22 microM which is about 16-fold higher than that for the intact enzyme (1.4 microM). The molecular activities of the fragment and the intact enzyme were 2.2 s-1 and 16.8 s-1, respectively. This indicates that the 62K domain enhances affinity for tRNA and it is responsible for the full activity of tRNA aminoacylation. These results do not support the "covalently linked dimer" hypothesis, but indicate that the alanyl-tRNA synthetase is a functional monomer consisting two large domains.

Alanine-tRNA Ligase↗
PubMed1984

Domain-structure of large monomeric alanyl-tRNA synthetase from Bombyx mori: evidence of a single catalytic domain.

Alanyl-tRNA synthetase of 115K dalton from Bombyx mori was cleaved into two fragments of 68K and 47K dalton with trypsin. The 47K fragment was active in aminoacylation of tRNA, whereas the 68K fragment inactive. The 47K and 68K fragments were located at the N- and C- terminal sides, respectively, in the intact enzyme. When the enzyme binds alanine specific tRNA, the tryptic digestion is inhibited. The Km value of the 47K fragment for tRNA was about 16-fold higher than that (1.4 microM) of the intact enzyme. The molecular activities of the 47K fragment and the intact enzyme were 2.2/sec and 16.8/sec, respectively. These results show that 1) Bombyx mori alanyl-tRNA synthetase functions in a monomeric state and 2) the C-terminal domain enhances affinity for tRNA and is responsible for full activity of aminoacylation.

Alanine-tRNA Ligase↗
PubMed1983

Cysts of the oral mucosa in newborns: a clinical observation.

Nodules or cysts of the oral mucosa occurred with an incidence of 88.7 per cent in 541 Japanese newborn infants. No infant was over 8 days old. This incidence is higher than that reported in Caucasian and Negro newborns. It may be suggested that the frequency of visible nodules have a close relation to growth and development in the fetal life, because the cysts seen in newborns can be recognized histologically in most fetuses, as demonstrated in other papers. Although a variety of terminology for these nodules have been used, these oral cysts can be classified as follows: gingival cyst in the newborn (dental lamina cyst) and median palatal mucosal cyst (Epstein's pearl).

Cysts↗
PubMed1983

Establishment of a human diploid cell strain.

A new human diploid fibroblast-like cell strain has been established from dermal tissue of a 2 months old female embryo. This cell strain showed diploid karyotype and has a finite life span of 95-100 generations. No spontaneous transformation was observed during the whole life span in vitro. This cell strain is susceptible to SV40 infection and can be transformed easily by it.

Cell Line↗
PubMed1983

Genetic mapping of bra genes affecting branched-chain amino acid transport in Pseudomonas aeruginosa.

Pseudomonas aeruginosa PAO mutants defective in the transport systems for branched-chain amino acids were isolated and characterized. Two mutations in strains selected for trifluoroleucine resistance, braA300 and braB307, were mapped in the met-9020-dcu-9108 and the nar-9011-puuC10 region, respectively. The mutation loci in strains selected for azaleucine resistance, braC310 and bra-311 through bra-314, were all located near the fla genes, with an order of region I fla-bra-region II fla. Strains with braA300 showed a marked reduction in the high-affinity branched-chain amino acid transport system (LIV-I) and a considerable decrease in the lower-affinity system (LIV-II). Strains with braB307 were found to be defective in the LIV-II system. Strains selected for azaleucine resistance were all defective only in the LIV-I system and fell into three phenotypically distinct classes. Strains with braC310 produced a binding protein for leucine, isoleucine, valine, alanine, and threonine (LIVAT-BP) altered in binding ability, indicating that the braC gene is the structural one for the LIVAT-BP. Strains with bra-311 or bra-312 showed a complete loss of production of the LIVAT-BP. Strains with bra-313 or bra-314 produced normal levels of functional LIVAT-BP, suggesting that these mutations are located in a gene(s) other than braC.

Amino Acids, Branched-Chain↗