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Biomedical subjects

S Noguchi

Publications and source records attributed to S Noguchi.

At least 649 records · Page 36Linked to original sources
PubMed1979

Specific fluorescent labeling of 7-(aminomethyl)-7-deazaguanosine located in the anticodon of tRNATyr isolated from E. coli mutant.

Under-modified E. coli tRNATyr that contains 7-(aminomethyl)-7-deazaguanosine in place of Q nucleoside can be chemically modified by dansyl chloride under neutral conditions. Fluorescent labelling specifically occurred only in the 7-(aminomethyl)-7-deazaguanine moiety. The modified tRNATyr was found to be active both in aminoacylation and in binding to ribosomes.

Anticodon↗
PubMed1979

Novel mechanism of post-transcriptional modification of tRNA. Insertion of bases of Q precursors into tRNA by a specific tRNA transglycosylase reaction.

The guanine insertion enzyme isolated from Escherichia coli (tRNA transglycosylase) catalyzed the incorporation of bases of Q (queuosine) precursors into E. coli undermodified tRNAAsn and tRNATyr. These bases of Q precursors were inserted in the first position of the anticodon of tRNASn and tRNATyr, replacing guanine originally located in that position. This is a novel type of post-transcriptional modification, inserting a modified base into the polynucleotide chain by cleavage of the N--C glycoside bond without breakage of the phosphodiester bond. One of the bases of Q precursors, 7-(aminomethyl)-7-deazaguanine, was found in the acid-soluble fraction of E. coli cells, supporting the conclusion that formation of Q, 7-(3,4-trans-4,5-cis-dihydroxy-1-cyclopenten-3-ylaminomethyl)-7-deazaguanosine, in tRNA in vivo actually proceeds by the tRNA transglycosylase reaction.

Escherichia coli↗
PubMed1979

Occurrence of 1-methyladenosine and absence of ribothymidine in transfer ribonucleic acid of Mycobacterium smegmatis.

The minor base composition of Mycobacterium smegmatis tRNA has been studied. Thin-layer chromatographic patterns of a ribonuclease T2 digest of mycobacterial tRNA indicated the presence of appreciable amounts of 1-methyladenosine (which is commonly present only in eucaryotic tRNA), dihydrouridine, and 7-methylguanosine. Ribothymidine was absent. The S-adenosylmethionine-dependent tRNA methylases of M. smegmatis catalyzed the formation of 1-methyladenosine when Escherichia coli tRNA was used as acceptor. Similarly, E. coli extracts methylated the tRNA of M. smegmatis, forming ribothymidine.

Adenosine↗
PubMed1978

Isolation of Q nucleoside precursor present in tRNA of an E. coli mutant and its characterization as 7-(cyano)-7-deazaguanosine.

One of the E. coli mutants selected for deficiency of modified nucleoside Q was found to contain an analogue of Q and normal guanosine in place of Q. The analogue of Q, designated as preQo, was isolated on a large scale from purified tRNATyr containing preQo. The structure of preQo was determined to be 7-(cyano)-7-deazaguanosine by comparison of its ultraviolet absorption spectra, thin-layer chromatographic mobility and mass spectrum with those of synthetic material.

Escherichia coli↗
PubMed1978

Structure determination of a nucleoside Q precursor isolated from E. coli tRNA: 7-(aminomethyl)-7-deazaguanosine.

A precursor of modified nucleoside Q isolated from E. coli methyl-deficient tRNA was determined to be 7-(aminomethyl)-7-deazaguanosine. The structure was deduced by means of its chromatographic and electrophoretic mobilities, and UV and mass spectra, in addition to comparison with the synthesized authentic compound. The same molecule is also found in tRNA of an E. coli mutant selected for deficient synthesis of modified nucleosides.

Chromatography, Thin Layer↗
PubMed1978

HLA and Japanese MS.

Determination of HLA-A, -B and -C types in 43 Japanese patients with multiple sclerosis (MS) and of DR type in 25 MS patients was carried out using antisera from the 7th International Histocompatibility Workshop. The results were compared with 46 controls typed simultaneously. Twenty-three patients were also tested for HLA-Dw2. The conclusions were: 1) There were no significantly higher occurrences of HLA-A3, B7, Dw2 or DRw2 in Japanese MS. 2) Japanese MS might nevertheless be associated with the human major histocompatibility complex, because HLA-B40 was significantly less frequent in MS and two anti HLA-DRw sera, 7w008 and 034, reacted positively more often against lymphocytes from MS patients.

Epitopes↗
PubMed1977

Regulation of antibody response in different immunoglobulin classes. II. Induction of in vitro IgE antibody response in murine spleen cells and demonstration of a possible involvement of distinct T-helper cells in IgE and IgG antibody responses.

In vitro induction of anti-DNP IgE as well as IgG1, IgG2a antibody responses was shown in murine spleen cell culture. Spleen cells primed three times with 1 mug of DNP-OA or DNP-Asc produced significant amounts of anti-DNP IgE as well as IgG antibodies by the in vitro stimulation with DNP-OA or DNP-Asc, respectively. Collaboration between DNP-primed B cells and carrier-primed T cells was required for the induction of both IgE and IgG antibodies with DNP-coupled T-dependent antigen. Carrier-specific T cells induced with a low dose of Asc (0.01 mug) showed helper function only on IgE antibody response, whereas T cells primed with a higher dose of Asc (10 mug) cooperated only with IgG-B cells. T cells primed with Asc in CFA showed helper function mainly on IgG antibody response but not on IgE antibody response. The result indicated the presence of a distinct population of T helper cells for IgE and IgG antibody responses. T-independent antigen (DNP-Ficoll) induced both anti-DNP IgE and IgG antibody responses in DNP-primed spleen cell population without the requirement of the collaboration of helper T cells.

Animals↗
PubMed1977

Tumor cell characterization of histiocytic medullary reticulosis.

Tumor cells from a 10-year-old boy was suspected histiocytic medullary reticulosis were examined and were found to have receptor sites for complement, the ability to phagocytize latex beads, and the electron microscopical picture of immature histiocytes. These findings strongly support the diagnosis of histiocytic medullary reticulosis. This disorder and the method of examination of the tumor cells are discussed.

Binding Sites, Antibody↗