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Biomedical subjects

A Yoshida

Publications and source records attributed to A Yoshida.

At least 1,225 records · Page 68Linked to original sources
PubMed1978

Studies on carbamoylphosphate synthetase in livers of rats fed a protein free diet supplemented with methionine and threonine and injected with N-acetylglutamic acid.

Supplementation of methionine and threonine to a protein free diet reduces urinary nitrogen excretion in rats, and it has been assumed that N-acetylglutamic acid may have a regulatory role in urea synthesis. The present paper reports the effect of supplementation of methionine and threonine on the levels of N-acetylglutamic acid and of carbamoylphosphate synthetase (EC 2.7.2.5) in liver. In spite of a significant decrease in urinary urea when methionine and threonine were supplemented to the protein free diet, the activity of carbamoylphosphate synthetase was not reduced. On the other hand, following injection of glutamic acid, N-acetylglutamic acid or N-acetylglutamine, the excretion of urinary urea of rats fed the protein free diet supplemented with methionine and threonine was significantly reduced whereas the level of carbamoylphosphate synthetase was the same in each group. Furthermore, the concentrations of N-acetylglutamic acid in liver of rats fed the protein free diet or the protein free diet supplemented with methionine and threonine were the same. Therefore, these results indicated that, when methionine and threonine were supplemented to the protein free diet, the changes in the levels of N-acetylglutamic acid and of carbamoylphosphate synthetase in liver does not contribute to the reduced body weight loss and urinary nitrogen excretion.

Ammonia↗
PubMed1978

Murine model for immunoprophylaxis of cytomegalovirus infection. I. Efficacy of immunization.

Murine cytomegalovirus was utilized as a model for human cytomegalovirus, which had no experimental animal, to study immunoprophylaxis of the cytomegalovirus infections. (1) Murine cytomegalovirus (MCMV) serially propagated in mouse embryonic fibroblasts had lost pathogenicity for weanling mice including neonatally thymectomized mice. (2) The cell culture-adapted MCMV was effective as a "live, attenuated virus vaccine" against challenge by virulent, mouse-passaged MCMV. (3) The immunization via intraperitoneal route protected mice from every parameter of MCMV infection. These included clinical signs, virus replication, histopathology and mortality. (4) The protective immunity was active against the virulent MCMV which was not neutralized by the rabbit anti-attenuated MCMV serum.

Animals↗
PubMed1978

Possible existence of hybrid glycosyltransferase in heterozygous blood group AB subjects.

The human blood group glycosyltransferases A and B have a dimeric structure, i.e., the A enzyme is an aa dimer and the B enzyme is a bb dimer. Considering the fact that the ABO blood group determinant are not x-linked, i.e. both A and/or B genes are expressed in a given cell, a hybrid enzyme (ab dimer) may exist in heterozygous A1B subjects. Because the A enzyme, but not the B enzyme, adsorbs with Sepharose 4-B, the adsorption characteristics of the A and B enzymes from plasma fo various phenotypes were examined to look for this hybrid enzyme. The A enzyme activity from A1 plasma and from a mixture of AU and B plasma was completely adsorbed to Sepharose 4-B, while 25-50% of A enzyme activity from heterozygous A1B plasma was not adsorbed. The results indicated that heterozygous A1B plasma contains an additional enzyme component which does not exist in a mixture of A1 and B plasma, suggesting the existence of a hybrid heterodimer (ab) in heterozygous A1B subjects.

ABO Blood-Group System↗
PubMed1978

Glucose 6-phosphate dehydrogenase variants: Gd (+) Alexandra associated with neonatal jaundice and Gd (-) Camperdown in a young man with lamellar cataracts.

Two male subjects are described, with unusual clinical presentations and with hitherto undescribed G6PD variants. The first, of Italian extraction, suffered from severe neonatal jaundice following maternal ingestion of fresh broad beans (Vicia fava) both prenatally and postnatally: the expression of the enzymatic defect was much more severe in the neonatal period than on retesting in adolescence, when biochemical characterization showed unique features which justify designation as a new variant Gd(+) Alexandra. The second patient, a boy of Maltese extraction who was found to have bilateral lamellar cataracts at the age of 4 years, was identified as G6PD deficient only as a result of a survey of children of Mediterranean origin with unexplained cataract formation; he has approximately 15% of normal enzyme activity, with another unique combination of biochemical characteristics which has led to its designation as Gd(-) Camperdown. Although this association may be coincidental, it prompts further attention to the possibility that under certain circumstances G6PD deficiency may favor cataract formation. The two cases illustrate the value of characterization of the mutant enzyme whenever unexpected clinical or laboratory results are obtained.

Adolescent↗
PubMed1978

Structural difference at the active site of dibucaine resistant variant of human plasma cholinesterase.

Human plasma cholinesterase from five different genotypes -- E1U E1U, E1U E1A, E1A E1A, E1U E1S, E1A E1S, and E1U E1U C5+ -- was purified 8,000 fold from serum by a two-step procedure involving chromatography on DEAE-cellulose and preparative disc electrophoresis. The esterases were labeled with diisopropyl-1, 3-C14-fluorophosphate (DFP) aminoethylated, and digested by trypsin. The trytic digests were subjected to high voltage electrophoresis, and the radioactive peptides were detected by radioautography. Comparison of the peptides revealed different electrophoretic mobilities of the usual and atypical (dibucaine resistant) plasma cholinesterase peptides. The results are consistent with a structural abnormality of the active center in the variant enzyme. No difference was observed an the esteratic site of the enzyme with C5 component.

Binding Sites↗
PubMed1977

Mouse liver metallothioneins. Complete amino acid sequence of metallothionein-I.

The amino acid sequence of thionein-I, a major mouse liver thionein, is presented. Thionein-I is a single chain polypeptide which consists of 61 amino acid residues and has the amino acid composition Cys20, Asp3, Asn1, Thr5, Ser9, Gln1, Pro2, Gly5, Ala5, Val2, Met1, Lys7, with N-acetylmethionine and alanine as NH2- and COOH-terminal amino acids, respectively. Automated sequence analysis of a major cyanogen bromide peptide consisting of 60 amino acid residues, as well as characterization of the peptides obtained from trypsin and papain digestion, led to the elucidation of the complete primary structure of this protein. Remarkable structural homology is observed between the mouse thionein-I and the equine renal thionein-1B (Kojima, Y., Berger, C., Vallee, B.L., and Kägi, J.H.R. (1976) Proc. Natl. Acad. Sci. U.S.A. 73, 3413-3417).

Amino Acid Sequence↗
PubMed1977

Purification and characterization of human hypoxanthine/guanine phosphoribosyltransferase.

Human hypoxanthine/guanine phosphoribosyltransferase (EC 2.4.2.8) was purified from red blood cells by the following two methods. Method A includes (a) elimination of hemoglobin by DEAE-cellulose, (b) DEAE-Sephadex chromatography, (c) specific elution of the enzyme from CM-Sephadex by pyrophosphate and (d) Sephadex G-100 gel filtration. Method B includes (a) elimination of hemoglobin by DEAE-cellulose, (b) acid treatment at pH 4.5, (c) ammonium sulfate fractionation, (d) DEAE-Sephadex chromatography, (e) heat treatment at 85 degrees C and (f) Sephadex G-100 gel filtration. Homogeneous enzyme preparation was obtained by the two methods with 8000-9000-fold purification. The sedimentation coefficient (S20,w) was 5.5--5.6 S, and the molecular weight of the enzyme was estimated at about 85000 by the sedimentation equilibrium method. The subunit molecular weight of the untreated protein and S-carboxymethylmaleyl protein was estimated as 41000--45000 by the sedimentation equilibrium method in the presence of guanidine hydrochloride. However, the subunit size estimated by the sodium dodecylsulfate gel electrophoresis was only 26000. Amino acid composition of the enzyme was determined. Glucosamine, sialic acid and hexose were not detected in the enzyme.

Amino Acids↗