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A Totsuka

Publications and source records attributed to A Totsuka.

14 recordsLinked to original sources
PubMed1992

Genetic relatedness of hepatitis A virus strains recovered from different geographical regions.

A pairwise comparison of the nucleic acid sequence of 168 bases from 152 wild-type or unique cell culture-adapted strains of hepatitis A virus (HAV) revealed that HAV strains can be differentiated genetically into seven unique genotypes (I to VII). In general, the nucleotide sequence of viruses in different genotypes differs at 15 to 25% of positions within this segment of the genome. Viruses from four of the genotypes (I, II, III and VII) were recovered from cases of hepatitis A in humans, whereas viruses from the other three genotypes (IV, V and VI) were isolated only from simian species developing a hepatitis A-like illness during captivity. Among non-epidemiologically related human HAV strains, 81 were characterized as genotype I, and 19 as genotype III. Within each of these major genotypes, there were two distinct groups (subgenotypes), which differed in sequence at approximately 7.5% of base positions. Each genotype and subgenotype has a characteristic amino acid sequence in this region of the polyprotein, with the most divergent genotypes differing at 10 of 56 residues. Strains recovered from some geographical regions belonged to a common (endemic) genotype, whereas strains from other regions belonged to several, probably imported, genotypes. Thus, HAV strains recovered in North America were for the most part closely related at the nucleotide sequence level, whereas in other regions, such as Japan and Western Europe, HAV strains were derived from multiple genotypes or sub-genotypes. These data indicate that patterns of endemic transmission can be differentiated from situations in which infections are imported due to travel.

Amino Acid Sequence↗
PubMed1992

[Family-acquired hepatitis A--prevalence of hepatitis A among the family in Aichi Prefecture, 1990].

We studied the transmission of hepatitis A virus (HAV) in 45 families, which members were diagnosed as hepatitis A in 8 hospitals in 1990. Feces and sera from 50 patients and their 126 family members were tested for HAV-specific antigen and IgM antibody by ELISA or polymerase chain reaction (PCR) technology. From the interval of the onset of hepatitis or detection of HAV antigen in feces, HAV transmission was recognized in 11 (24.4%) of 45 families. The transmission was found to be concerned with contacts of the children and that from children to parents was found in 4 families and the reverse in 2. HAV antigen was detected from feces of 4 family members before onset of icterus by ELISA and furthermore, 3 by PCR. It was indicated that these methods would be used to prevent the transmission in a family, day-care centers, or institutions for the mentally retarded.

Adolescent↗
PubMed1987

Expression of soybean glycinin subunit precursor cDNAs in Escherichia coli.

As the cDNAs encoding A1aB1b and A2B1a subunit precursors of the glycinin A2 subfamily contain a unique NcoI site sequence, (A)CCATGG, occurring at their translation initiation sites, plasmids were constructed to direct the synthesis of those precursor proteins by inserting NcoI/PstI fragments derived from those cDNA clones into the NcoI/PstI-pKK233-2 expression vector in Escherichia coli MV1190, respectively. The resultant plasmids directed the expression of 57-kDa protein components that have molecular masses in agreement with those of the in vitro translation products directed by glycinin A2 subfamily mRNAs, by the addition of isopropyl beta-D-thiogalactoside. These proteins, which comprised as much as 1% of the total bacterial protein, are immunoprecipitable with rabbit antibodies specific for glycinin subunits. This procedure makes glycinin subunits available as a model for studying structure-function relationships in seed proteins using site-directed mutagenesis. This is the first expression of glycinin-like storage protein in E. coli.

DNA↗
PubMed1978

Aggregation of enterovirus small plaque variants and polioviruses under low ionic strength conditions.

Virion aggregation in low ionic conditions was observed with small plaque variants of Coxsackievirus type B3 and Echovirus types 4 and 11 by sedimentation and filtration methods. Inclusion of salts or DEAE-dextran into the media prevented or reversed virion aggregation. The effect of pH on aggregate formation in low ionic strength solutions was also investigated with various strains of poliovirus. Type I Sabin strain formed aggregates even at high pH, while Mahoney strains did so only below pH 6.5. Type 2 virus, Sabin and MEF1 strains, and type 3 virus, Sabin, Saukett and Suwa strains, showed an intermediate behaviour between the two type 1 strains, except MEF1-LB strain, a clone obtained from MEF1 strain under acidic overlay, which showed little tendency to aggregate. These results were compared with the degree of the d character of the strains. Besides the effect of inhibiting virion aggregation, the inclusion of DEAE-dextran into a sucrose gradient slowed the sedimentation of some of the viruses in low ionic strength solutions.

Cell Line↗
PubMed1975

Poly(A) polymerase in quail oviduct. Changes during estrogen induction.

A nuclear poly(A) polymerase has been isolated from oviducts of immature quails. It could be purified 4300-fold. The enzyme depends specifically on ATP as substrate and requires Mg2+. The most effective primer for the enzyme is a polynucleotide, isolated from oviduct tissue. A poly(A) sequence to a maximum of 60 AMP residues is covalently linked per primer molecule. The poly(A)-rich product of the enzymatic reaction can be annealed to oligo(dT)-cellulose. The purest fraction does not contain any detectable poly(A)-degrading enzyme activity. Only very low activities of RNA polymerase are present. The poly(A polymerase activity in the assay with ATP is reduced by the ATP analogue, beta, lambda-ATP-methylene-diphosphonate. Both K-m and V are lowered. The ATP analogue is incorporated to a smaller extent into the poly(A) sequence, synthesized by the enzyme. Several other analogues of adenine, adenine nucleosides and adenine nucleotides are without effect on the enzymatic reaction. By these properties poly(A) polymerase can be distinguished from RNA polymerases form I and form II, isolated from the same tissue. Actinomycin D and alpha-amanitin failed to inhibit poly(A) polymerase activity. The activity of poly(A) polymerase has been determined during primary stimulation with the estrogen analogue diethylstilbestrol (daily injection for 5 days), after withdrawal of the hormone for 17 days and after secondary stimulation with the hormone analogue. The enzyme activity does not change during primary stimulation, withdrawal of the hormone or secondary stimulation. However the activity of a poly(A) degrading enzyme, localized in the nucleus, is reduced in oviducts from hormone-treated quails.

Adenine Nucleotides↗
PubMed1975

[Method for determination of the bleomycin inactivating enzyme acitivity in tissues].

An enzyme that inactivates Bleomycin (BLM) can be extracted from tissue. The activity of this enzyme varies markedly in different tissues. In the present paper, a method is described by which the activity of the BLM-inactivating enzyme in different organs and tissues of mice can be determined. The highest activity is found in liver; lower enzyme concentrations occur in the testis, spleen, lung and brain. In skin this enzyme is almost completely missing.

Animals↗