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Biomedical subjects

S Nishimura

Publications and source records attributed to S Nishimura.

At least 973 records · Page 54Linked to original sources
PubMed1977

Isolation of mammalian tRNAAsp and tRNATyr by lectin-Sepharose affinity column chromatography.

tRNAAsp from rabbit liver, rat liver and rat ascites hepatoma was readily isolated by concanavalin A-Sepharose (Con A-Sepharose) affinity column chromatography. tRNATyr from these sources was extensively purified by Ricinus communis lectin-Sepharose column chromatography. These results, together with the chromatographic behaviour of four tRNAs (tRNATyr, tRNAHis, tRNAAsn and tRNAAsp) on acetylated DBAE-cellulose column chromatography suggested that tRNAAsp contains a Q nucleoside species having a mannose moiety while tRNATyr contains Q nucleoside with galactose. The sugars attached in 4-position of cyclopentene diol in the Q molecule are therefore not present at random in the four tRNAs, but present only in each specific tRNA. This is the first case which shows that plant agglutinin interacts with nucleic Acid as well as polysaccharide and glycoproteins.

Animals↗
PubMed1977

Proton magnetic resonance spectra of tRNA-Met-f from Thermus thermophilus.

220 MHz proton magnetic resonance spectra of tRNAs in bulk and tRNA-Met-f from Thermus thermophilus have been measured and compared with those of tRNAs from E. coli. Temperature dependences and chemical shift positions of the bulk tRNAs are well explained by the difference in their GC contents. It is known that the base sequence of the double helical regions in the cloverleaf structure of T. thermophilus tRNA-Met-f is different from that of E. coli tRNA-Met-f only at two positions in TpsiCarm; one more C:G pair is contained instead of a U:G pair of E. coli tRNA-Met-f and a C:G pair of E. coli is replaced by a G:C pair. In spite of the resembrance in the base sequences, nmr patterns around 13 ppm are fairly different from each other. The difference is discussed in relation with their tertiary structures and with the origin of chemical shift displacements.

Base Sequence↗
PubMed1977

Rabbit liver tRNA1Val:I. Primary structure and unusual codon recognition.

The major valine acceptor tRNA1Val from rabbit liver was purified and its nucleotide sequence determined by in vitro [32P] - labeling with T4 phage induced polynucleotide kinase and finger-printing techniques. Its primary structure was found to be identical with the major valine tRNA from mouse myeloma cells. According to the wobble hypothesis this tRNA, which exclusively has an IAC anticodon, should decode the valine codons GUU, GUC and GUA only. However, this tRNA recognizes all four valine codons with a surprising preference for GUG. It is unknown whether this is due to the lack of A37 modification next to the 3' end of the anticodon IAC. The nature of the inosine-guanosine interaction remains to be clarified.

Animals↗
PubMed1977

A rapid cytosine-specific modification of E. coli tRNA Leu 1 by semicarbazide-bisulfite, a probe for polynucleotide conformations.

Cytosine residues in 32P-labeled E. coli tRNA Leu 1 were modified by treatment of the tRNA with the semicarbazide-bisulfite reagents [Hayatsu, H. (1976) Biochemistry 15, 2677-2682]. Analysis of the modification sites showed that only four cytidine residues, i.e. C35, C53, C85 and C86, reacted. They were identical with the cytidines of this tRNA accessible to methoxyamine [Chang, S. E. and Ish-Horowicz, D. (1974) J. Mol. Biol. 84, 375-388] and the accessibility was consistent with the conformational features recognized for tRNA in general. The rapidity and the simple nature of this modification demonstrate that the semicarbazide-bisulfite reaction is a useful tool in studying conformations of polynucleotides.

Base Sequence↗
PubMed1977

Enzymatic synthesis of Q nucleoside containing mannose in the anticodon of tRNA: isolation of a novel mannosyltransferase from a cell-free extract of rat liver.

The Q nucleosides isolated from rabbit liver tRNA are known to have sugars (mannose or galactose) linked to their cyclopentene diol moiety. A Q nucleoside containing mannose (manQ) was synthesized by a cell-free system from rat liver, using purified E. coli tRNAAsp as an acceptor and GDP-mannose as a donor molecule. The novel mannosyltransferase catalyzing this reaction was purified from a particulate-free soluble enzyme fraction and found to be strictly specific for tRNAAsp. These results, together with the anomeric configuration of mannose in Q nucleoside, indicate that no lipid intermediate is involved in the biosynthesis of Q nucleoside.

Animals↗
PubMed1977

Deficiency of S-adenosylmethionine-homocysteine methyltransferase activity in hepatoma cells.

S-Adenosylmethionine-homocysteine methyltransferase, which catalyzes synthesis of methionine from homocysteine, with the use of S-adenosylmethionine as the methyl donor, is absent in tumor tissue such as rat ascites hepatoma and Morris hepatoma but is present in rat liver homogenate. Absence of the enzymatic activity in tumor cells is not due to the action of an inhibitor. S-Adenosylhomocysteine hydrolase, however, is present in both rat liver and hepatoma tissue.

Animals↗
PubMed1977

[Traumatic cerebral aneurysm showing remarkable extravasation into the lateral ventricle--report of a case in an infant (author's transl)].

A case of traumatic cerebral aneurysm showing remarkable extravasation into the lateral ventricle was reported. This 9-month-old female baby fell down from 30 cm height and hit the right occipital area against the concrete floor. Immediately after the accident she cried, but three minutes later apnea and cardiac arrest were developed. On admission, plain craniogram showed a linear skull fracture extending from the parietal to occipital area on her right side. Since the retrograde vertebral angiography performed through the right brachial artery revealed no finding of hematoma, the patient was treated conservatively. On the third day from the accident, she developed convulsion on her right leg and the left CAG showed an aneurysm of 5 mm X 3 mm size at C2 portion of the carotid artery but no hematoma was detected. As plain craniograms taken with intervals revealed progressive suture separation, V-P shunt was performed. Immediately after the operation, mydriasis was noted on the left side. The left CAG showed remarkable extravasation of the contrast medium from the aneurysm into the left lateral ventricle. Trapping of the aneurysm was performed and the clot was removed out of the left lateral ventricle as much as possible. Ten months after surgery, she was able to eat. Development and treatment of traumatic aneurysms and extravasation from aneurysms of various origin have been discussed.

Brain Injuries↗