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Biomedical subjects

S Nishimura

Publications and source records attributed to S Nishimura.

At least 955 records · Page 53Linked to original sources
PubMed1978

Identification of a mutagenic substance in a spice, sumac, as quercetin.

The mutagenicity of a spice, sumac, was demonstrated on Salmonella typhimurium strain TA98. The active principle was purified and characterized by thin-layer chromatography, UV-absorption spectroscopy and mass spectrometry. All the mutagenic activity of sumac was found to be due to quercetin.

Chromatography, Thin Layer↗
PubMed1978

Detection of unique tRNA species in tumor tissues by Escherichia coli guanine insertion enzyme.

The guanine insertion enzyme from Escherichia coli catalyzes exchange of guanine located at the first position of the anticodon of tRNA with radioactive guanine (N. Okada and S. Nishimura, unpublished data). tRNA isolated from various tumors, including slowly growing Morris hepatoma 7794A, incorporated considerable guanine with E. coli guanine insertion enzyme, whereas tRNA isolated from all normal tissues so far tested, except regenerating rat liver, incorporated scarcely any. In the rat ascites hepatoma AH7974, the guanine was mostly incorporated into minor isoaccepting species of tRNAAsp that contained the guanine residue instead of Q base in the first position of the anticodon. This is a sensitive and easy method for identifying unique tRNA species in tumor tissues.

Animals↗
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

Crystallization of arginine-, formylmethionine-tyrosine-, and glycine-transfer RNAs from Escherichia coli.

Crystals as large as 0.5 X 0.3 X 0.2 mm of purified arginine-transfer RNA from Escherichia coli have been prepared by a vapour diffusion method. X-ray diffraction photographs showed that the crystals gave reflections up to 3.7 A spacing. They have a trigonal space group P31 2 1 (OR P32 2 1) and cell-dimensions a=97.2, b=97.2, c=94.8A. Crystals of a mercury derivative of this transfer RNA have also been obtained, and an X-ray diffusion photography of one of them is presented. Formylmethionine-transfer RNA from E. coli was crystallized in various forms, and the appearance of the polymorphs was found to depend upon the amount of spermine in the solution from which the crystallization took place. Crystals of tyrosine-transfer RNA and glycine-transfer RNA have also been obtained.

Arginine↗
PubMed1978

[Hydrocortisone for the treatment of cerebral vasopasm--(1) experiments in dogs (author's transl)].

The usefulness of hydrocortisone for the treatment of cerebral vasospasm was investigated using dogs by measuring changes in cerebral arterial diameter in angiograms as well as in other parameters such as blood pressure, intracranial pressure and CBF. The intrathecal (50-300 mg) or intravenous (100 mg/kg) injection of hydrocortisone resulted in a marked dilatation of cerebral arteries both in control animals and vasospastic animals after subarachnoid hemorrhage. The intrathecal injection caused a temporary rise in blood pressure immediately following the injection. Cerebrospinal fluid pressure was increased progressively. On the other hand, the intravenous injection resulted in a fall in blood pressure and a transient rise in cerebrospinal fluid pressure. CBF showed a tendency to increase both with intrathecal and intravenous injection. With intravenous injection a high CSF level of cortisol was found 1 and 2 hours after the injection and it was correlated to the degree of cerebral arterial dilatation, indicating that a significant amount of hydrocortisone could penetrate into the CSF and dilate the intracranial vessels by its direct pharmacological action.

Animals↗
PubMed1977

Detection of nucleoside Q precursor in methyl-deficient E.coli tRNA.

32P-Labeled tRNAAsn was isolated from methyl-deficient E. coli tRNA. Nucleotide sequence analysis showed that tRNAAsn contains three derivatives of the Q nucleoside, possibly Q precursors, in addition to guanosine in the first position of the anticodon. One of the Q precursors was isolated on a large scale. Its UV spectra were identical with those of normal Q, indicating that 7-deazaguanosine structure having a side chain at position C-7 is complete in the Q precursor. No radioactivity was incorporated into Q or Q precursors from either [methyl-14C]methionine, [1-14C]methionine or [U-14C]methionine, showing that methionine was not directly involved in the formation of Q.

Asparagine↗