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S Sakamoto

Publications and source records attributed to S Sakamoto.

At least 595 records · Page 33Linked to original sources
PubMed1987

Proton nuclear magnetic resonance study on the solution conformation of human epidermal growth factor.

This paper describes elucidation of the conformation of the human epidermal growth factor (hEGF) in an aqueous environment, using one- and two-dimensional proton nuclear magnetic resonance methods. The noted structural information obtained is that a rigid core structure is formed by the interplay of the three disulfide bridges and an antiparallel beta-sheet consisting of Val-19 to Glu-24 and Asp-27 to Asn-32. Furthermore, the hydrophobic amino acid residues of the long C-terminal segment fold back to interact locally with residues in the beta-sheet. It is suggested that the C-terminal residues play an inevitable role in the formation of the receptor-binding site.

Binding Sites↗
PubMed1987

Relative activities of thymidylate synthetase and thymidine kinase in 1,2-dimethylhydrazine-induced colon carcinomas in rats.

Thymidylate synthetase (TS) and thymidine kinase (TK) are known to catalyse the methylation of dUMP for the de novo synthesis of dTMP and the phosphorylation of thymidine for the salvage synthesis of dTMP in the pyrimidine pathway, respectively. High TS and TK activities and the existence of TK isozymes have been observed in rapidly proliferating tissues. TS and TK activities in 1,2-dimethylhydrazine (DMH)-induced colon carcinomas in rats increased significantly to 331 and 207% of the activities in normal colon, respectively, and were well correlated inversely (y = -0.93x + 5.24), with a correlation coefficient of -0.787. The colonic TK isozymes were separated into two types by DEAE-cellulose column chromatography. The TK isozyme eluted from the column by the elution buffer alone without NaCl was markedly higher (23.6-fold) in activity in DMH-induced colon carcinoma than in normal control colon and was not affected by deoxycytidine triphosphate. This isozyme, whose mol. wt is 100,000 by h.p.l.c., is thought to be closely involved in rapid DNA replication. These results indicate that early biochemical changes in DMH-induced colon carcinoma in rats may serve as a useful model and provide valuable insight into the mechanisms involved in colonic carcinogenesis.

1,2-Dimethylhydrazine↗
PubMed1987

Purification and characterization of phospholipase A2 from Trimeresurus gramineus venom.

Phospholipase A2 was purified to homogeneity from the venom of Trimeresurus gramineus (the Green Habu snake) via three steps consisting of Sephadex G-75, DEAE-cellulose, and DEAE-Toyopearl 650M column chromatographies. Molecular weight determinations showed that the enzyme consists of a single polypeptide chain with a molecular weight of approximately 14,000. The isoelectric point was 4.5. The enzyme is characterized by high contents of acidic amino acids, glycine, and half-cystine. Calcium ion was essential for eliciting activity. The enzyme was inactivated by alkylation of a single histidine residue with p-bromophenacyl bromide following pseudo first-order kinetics, and the rate of the inactivation was depressed in the presence of Ca2+. The N-terminal sequence of this enzyme determined to the 40th residue was found to be highly homologous to that of Trimeresurus okinavensis phospholipase A2 but not to that of Trimeresurus flavoviridis phospholipase A2. The phenylalanine residue at the 27th position of T. gramineus phospholipase A2 is noteworthy because all other phospholipases A2, with only two exceptions, contain a tyrosine residue at this position.

Acetophenones↗
PubMed1987

Yeast plasmids resembling 2 micron DNA: regional similarities and diversities at the molecular level.

The nucleotide sequence of two Zygosaccharomyces plasmids, pSB2 (5,415 base pairs), isolated from Zygosaccharomyces bailii, and pSM1 (5,416 base pairs), isolated from Zygosaccharomyces fermentati Naganishi, was determined. The predicted amino acid sequences of open reading frames among six yeast plasmids that resemble 2 microns DNA indicated regional sequence similarities among FLP proteins. Greater similarities were seen among Zygosaccharomyces plasmids (pSB2, pSB3, pSR1, and pSM1) than other combinations. A putative recognition site for the FLP enzyme of a Zygosaccharomyces plasmid also showed some conservation, especially in the 4 nucleotides flanking the central spacer region. From comparative studies of the sequences of putative genes of each plasmid, we propose an apparent phylogenetic relationship among yeast plasmids resembling 2 micron DNA. Among the Zygosaccharomyces plasmids, pSB2 and pSR1 are most closely related, since not only were the FLP enzymes of these two plasmids most closely related, but also the amino acid sequence of the putative P gene of pSR1 showed clear homology with that of open reading frame B of pSB2.

Amino Acid Sequence↗
PubMed1987

[A comparative study of apical hypertrophy with giant negative T waves and non-obstructive hypertrophic cardiomyopathy: evaluation by computed tomography, echocardiography and left ventriculography].

To assess the relationships between patterns of left ventricular hypertrophy and giant negative T waves (greater than 15 mm, GNT), 24 patients with GNT were categorized in two groups: Group A consisted of 12 patients with GNP but without left ventricular hypertrophy (greater than 13 mm at the chorda level of the interventricular septum and/or left ventricular posterior wall by UCG, LVH); and group-B consisted of 12 patients with GNT and LVH. Twelve patients with LVH but no GNT compromised as group-C. Left ventriculography (LVG) was performed, and left ventricular mass (LVM) and apical hypertrophy were assessed by CT. The configurations of the end-diastolic left ventricle by LVG (RAO 30 degrees) were as follows, by group: A: spade in eight patients and papillary muscle hypertrophy (PMH) shape in four. B: spade in five, PMH in four, banana in one and oval in two. C: banana in nine and oval in three. The LVM (g/BSAm2) were as follows; A: 121.5 +/- 14.9, B: 130.5 +/- 14.8, C: 190.6 +/- 42.1 (C greater than A, B, p less than 0.001). The apex/base ratios calculated by CT were as follows; A: 1.43 +/- 0.31, B: 1.21 +/- 0.19, C: 1.09 +/- 0.20 (C greater than A, p less than 0.05). The left ventricular mass in patients with GNT was less than that of those without GNT. Giant negative T waves were most often associated with apical hypertrophy.

Adult↗
PubMed1987

Decreased interleukin 1 activity in culture supernatant of lipopolysaccharide stimulated monocytes from patients with liver cirrhosis and hepatocellular carcinoma.

Immunoregulatory function of peripheral blood monocytes was studied in patients with hepatocellular carcinoma (HCC) and liver cirrhosis (LC), by assaying interleukin 1 (IL-1) and prostaglandin E2 (PGE2) in the culture supernatant of lipopolysaccharide-stimulated monocytes. IL-1 activity of the monocyte culture supernatant without indomethacin was decreased in patients with HCC and LC, compared with that of controls. The activity was lower in patients with HCC than that in those with LC. The PGE2 content of the culture supernatant of monocytes from patients with LC and HCC was increased, compared to normal controls. To avoid the effect of PGE2 on the IL-1 assay, we cultured the monocytes with addition of indomethacin and assayed IL-1 activity in the culture supernatant. As a result, monocyte IL-1 production was increased in patients with HCC and LC, compared with normal controls. The decrease in IL-1 activity of the supernatant without indomethacin of patients with LC and HCC was considered to be due to increased secretion of PGE2 by the monocytes. Therefore, monocytes from patients with HCC and LC had an increased capacity of secreting both IL-1 and PGE2 over normal controls, but the effect of the suppressor function (PGE2 secretion) dominated in these patients.

Adult↗
PubMed1987

[A case of giant obsolete hydrocele testis].

A 58-year-old man visited the urological clinic in Prefectural Tohkamachi Hospital with complaint of swelling of bilateral scrotal contents. He had no history of fever, pain or difficulty of urination. Physical examination revealed a giant mass of adult-head size in right scrotum and left inguinal hernia of fist growth. Surgical extirpation of the right scrotal mass and left inguinal herniorrhaphy was performed and the mass was diagnosed as obsolete hydrocele testis and weighed 1,600 g. The excised hydrocele sac showed marked thickening and dark brown pus amounted to about 1,400 ml, which was negative in bacterial culture. Histological examination revealed partial deposits of cholesterol and calcification in tunica vaginalis with extremely atrophic testis and destructive spermatogenesis. The findings suggested the existence of long-term infection in hydrocele testis. The etiology and pathogenesis of this disease is discussed.

Calcinosis↗