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Biomedical subjects

Y Kawata

Publications and source records attributed to Y Kawata.

At least 163 records · Page 9Linked to original sources
PubMed1983

NMR titration studies of histidine 57 and the [methylene-13C]PMS group in the phenylmethanesulfonyl (PMS) derivative of Streptomyces erythraeus trypsin.

1H and 13C NMR titrations were performed on PMS-St. trypsin derived by PMSF modification of Ser 195 in Streptomyces erythraeus trypsin, which is devoid of auto-catalytic degradation activity at pH approximately 8. NMR titration of the imidazole C2 proton showed that His 57 had the pKa value of 6.9 in both native St. trypsin and PMS-St. trypsin, suggesting that the adjacent hydroxyl group of Ser 195 had no effect or a very weak effect on the acid-base properties of the imidazole ring in the catalytic triad. A small change in the chemical shift of the isotopically enriched methylene carbon in the PMS moiety of [methylene-13C]PMS-St. trypsin was observed between pH 6 and 8. The titration curve had an inflexion at pH 6.9 and the mode of transition was apparently sigmoidal, although a Hill coefficient of more than unity was suggested. It is thus likely that His 57 is responsible for this transition. Based on these results, the role of His 57 in the catalytic triad of the active site in serine protease is discussed.

Amino Acids↗
PubMed1983

[A case of paraganglioma of the urinary bladder].

Herein we report a case of primary paraganglioma of the urinary bladder. A 21-year-old woman was admitted to an emergency hospital, because of gross hematuria, dysuria and complete urinary retention. Pelvic CT scan and ultrasonic examination revealed a bladder tumor and coagulated blood mass, then she was referred to our clinic for further treatment. On cystoscopy a dark brown lobular tumor was seen on the anterior wall. The bladder tumor was removed by partial cystectomy. The operative specimen measured 6 X 4 X 3 cm and weighed 50 g. Histological examination showed it to be a paraganglioma of the urinary bladder, which was chromaffin positive. Her serum and urinary catecholamine level were within the normal range after operation. She is now ten months postoperative, free from hematuria, and showing no other symptoms or signs of disease including metastasis.

Adult↗
PubMed1982

Primary and secondary structure of 5.8S rRNA from the silkgland of Bombyx mori.

Nucleotide sequence of 5.8S rRNA of the silkworm, Bombyx mori has been determined by gel sequencing methods. The 5.8S rRNA was the longest so far reported, with the 5'-terminal sequence several nucleotides longer than those of the other organisms. Upon constructing the secondary structure in accordance with the "burp gun" model (12), the Bombyx 5.8S rRNA formed a wide-open "muzzle" due to several unpaired bases at the ends. The overall structure also appeared less stable with less G . C pairs and more unpaired bases than that of the HeLa 5.8S rRNA. These structural features may be essential for those 5.8S rRNAs which interact with 28S rRNAs containing the hidden break to form a stable complex.

Animals↗
PubMed1982

Nucleotide sequence and thermal property of 5S rRNA from the elder aphid. Acyrthosiphon magnoliae.

The nucleotide sequence of 5S rRNA from the elder aphid. Acyrthosiphon magnoliae was determined by using postlabeling sequencing techniques. The aphid 5S rRNA consists of 120 nucleotides and the sequence differs from those of Bombyx and Drosophila 5S rRNAs in 14 and 16 positions, respectively. A secondary structure model based on the sequence has two distinctive features : the helix I is shorter and the total free energy lower. Judging from the thermal profile, the aphid 5S rRNA likely assumes a conformation somewhat different from those of the other two insects.

Animals↗
PubMed1981

[Solubility of metal components into tissue culture medium from dental amalgams (author's transl)].

Solubility of metal components into tissue culture medium, YLH, from various dental amalgams including high copper, conventional and copper amalgam was measured with atomic absorption spectrometry. The results obtained were as follows.: 1. Mercury solubility was found much in all the dental amalgams after one day extraction. This was followed by gradual increase in solubility in the high copper amalgams until after seven days. On the otherhand, initial high solubility was maintained in conventional and copper amalgams through the whole experimental period. 2. Higher solubility of silver and copper was recorded in the high copper amalgams. 3. Zinc was only found in Dispersalloy and copper amalgam. 4. Tin was unable to be measured in all the amalgams examined. It was considered that the present results could shed a light on the mechanism for cytotoxicity yielding of the dental amalgams.

Culture Media↗