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Biomedical subjects

A Oka

Publications and source records attributed to A Oka.

At least 127 records · Page 7Linked to original sources
PubMed1981

Nucleotide sequence of the asnA gene coding for asparagine synthetase of E. coli K-12.

We have subcloned the asnA gene of E. coli K-12, a gene coding for asparagine synthetase, from a previously cloned 6 mega-dalton segment of E. coli chromosome containing the DNA replication origin, ori, and asnA. The complete nucleotide sequence of the asnA gene was determined: the region of the structural gene extends 990 base-pairs at nucleotide positions 1434-2423 (see Fig. 3), which codes for a polypeptide of 330 amino-acid residues with a molecular weight of 36,688 daltons. The nucleotide sequences of the promoter and the ribosome-binding site of the gene are also assigned. We discuss the properties of its polypeptide.

Amino Acid Sequence↗
PubMed1980

Replication origin of the Escherichia coli K-12 chromosome: the size and structure of the minimum DNA segment carrying the information for autonomous replication.

A DNA fragment containing the replication origin of the Eschericia coli K-12 chromosome was inserted in two correlations at either the BamHI or SalI site of pBR322 DNA. All the resulting hybrid plasmids were found to replicate in both polA and polA+ cells, whereas pBR322 replicates only in polA+ cells. This characteristic provided a method for assaying the autonomously replicating ability (Ori function of the E. coli origin. In order to define the minimum DNA region (ori) that determines Ori function, deletions of various sizes were introduced from either side of the ori-containing segment in the hybrid plasmids by in vitro techniques, and the correlation between the Ori phenotype and nucleotide sequence of the deletion derivatives was analyzed. It was found that the left end of ori is between positions 23 and 35, and the right end is either position 266 or 267 in our nucleotide coordinate (Sugimoto et al., 1979). Therefore, ori is present within a region of minimum 232 base pairs and maximum 245 base pairs in length. The Ori+ and Ori- phenotypes were clearly resolved at both sides of these boundaries by the above assay procedure. To obtain information about the effect of mutations in the internal region of the defined ori stretch, short sequences were inserted or deleted in vitro in the vicinity of several restriction sites within ori on the hybrid plasmids. Most of these plasmids carrying modified sequences showed Ori- phenotype, suggesting that most parts of the ori stretch play important roles in Ori function.

Base Sequence↗
PubMed1980

Parathyroid adenoma found by vertebral vein sampling.

We report on a 33-year-old man with hypercalcemia and recurrent nephrolithiasis, who underwent the first neck exploration for primary hyperparathyroidism on September 27, 1973. No tumor was found and bilateral upper normal parathyroid glands were removed. However, hypercalcemia persisted postoperatively. Selective venous sampling for radioimmunoassay of parathyroid hormone 5 years later revealed a sharp unilateral gradient in the right vertebral vein. On November 2, 1978 the second neck exploration was performed and a right lower parathyroid adenoma was removed from the right lateral wall of the esophagus. Postoperatively, the serum calcium level decreased to 8.8 to 9.3 mg./dl. and convalescence was uneventful. In this case the pathway of parathyroid venous effluent might have been changed by the previous neck exploration and probably drained anomalously through the vertrbral vein. Selective venous sampling for radioimmunoassay of parathyroid hormone should include samplings from the vertebral veins as well as the thyroid veins, especially in cases with 1 or more previous neck explorations.

Adenoma↗
PubMed1980

An outbreak of acute enteritis due to Campylobacter fetus subspecies jejuni at a nursery school of Tokyo.

An outbreak of acute enteritis due to Campylobacter fetus subspecies jejuni involving a total of 35 out of 74 children occurred at a nursery school of Tokyo in January 1979 and lasted for 7 days. It was the first case of a community outbreak of the disease to be recognized in Japan. The major symptoms observed in the patients consisted of diarrhea (88%), fever (82%), abdominal pain (39%), and vomiting (6.1%). The rate of isolation of the organism from the patients was 39%. Sera of four patients showed elevated agglutinin titers against the organism ranging from 1:80 to 1:320. Although it is suggested that the outbreak was caused by a communal lunch or between-meal snacks prepared by and provided at the nursery school, the incriminated food, source and route of contamination could not be pinpointed.

Acute Disease↗
PubMed1979

Nucleotide sequence of small ColE1 derivatives: structure of the regions essential for autonomous replication and colicin E1 immunity.

A small ColE1 derivative, pAO2, which replicates like the original ColE1 and confers immunity to colicin E1 on its host cell has been constructed from a quarter region of ColE1 DNA (Oka, 1978). The entire nucleotide sequence of pAO2 (1,613 base pairs) was determined based on its fine cleavage map. The sequence of a similar plasmid, pAO3, carrying additional 70 base pairs was also deduced. The sequence in the region covering the replication initiation site on these plasmids was consistent with those reported for ColE1 by Tomizawa et al. (1977) and by Bastia (1977). DNA sequences indispensable for autonomous replication were examined by constructing plasmids from various restriction fragments of pAO2 DNA. As a result, a region of 436 base pairs was found to contain sufficient information to permit replication. The occurrence of initiation and termination codons and of the ribosome-binding sequence on pAO2 DNA suggests that a polypeptide chain consisting of 113 amino acid residues may be encoded by the region in which the colicin E1 immunity gene has been mapped.

Base Sequence↗
PubMed1979

Nucleotide sequence of Escherichia coli K-12 replication origin.

From subfragments of an EcoRI fragment (9 kilobase pairs) that contained the replication origin of the Escherichia coli chromosome and had been cloned as a recombinant with a nonreplicating DNA fragment coding for ampicillin resistance, small derivative plasmids were constructed. The smallest of these, pTSO151, contained a segment of 463 base pairs as the chromosomal component. Another plasmid, pSY134, constructed from BamHI digests of the EcoRI fragment and mini-F(pMF21), contained a region of 422 base pairs identical with a corresponding region in pTSO151. We conclude that the replication origin of E. coli chromosome is located within this 422-base-pair segment. The nucleotide sequence of this segment is presented.

Base Sequence↗
PubMed1979

The structure of a transcriptional unit on colicin E1 plasmid.

In an RNA-synthesizing system in vitro, a low-molecular-weight RNA consisting of about 110 residues (RNA-I) was efficiently synthesized on DNA of colicin E 1 plasmid (ColE1) and its deletion derivatives. The promoter site for RNA-I was analysed by testing the RNA polymerase-binding ability and template activity of restriction fragments; it was mapped in the region between the replication initiation site and the colicin immunity gene of ColE1. The direction of transcription was determined by hybridization tests to the separated strands of the template. The DNA region directing RNA-I was sequenced, and RNA-I was assigned on the sequence based on the nearest-neighbour data of RNA. The sequences of its promoter and terminator regions were also deduced. Although the function of this small RNA species is unknown, a unique secondary structure could be constructed from its sequence and sensitivity to RNase.

Bacteriocin Plasmids↗
PubMed1979

Macroglobulinemia Waldenström complicated by autoimmune hemolytic anemia, meningeal sign and femoral lysis.

A necropsied case of macroglobulinemia Waldenström with unusual complications was presented; the patient was found to have autoimmune hemolytic anemia, first. During the course of its treatment, he developed monoclonal immunoglobulin M in serum together with lytic osseous lesion in both femurs, and died of meningeal involvement by tumor cells. Clinically, he had hepatosplenomegaly and generalized lymphadenopathy. The macroglobulin was kappa type of light chain, ultracentrifugation showed sharp spike of 21S in 18.6%, and myelogram revealed increased lymphocytoid series of 29.6%. It was proved that autoantibody causing autoimmune hemolytic anemia was composed of IgG and macroglobulin itself had no activity as an anti-red cell antibody. An emphasis was made that autoimmune hemolytic anemia followed by macroglobulinemia is based on the state of immunodeficiency of this patient.

Anemia, Hemolytic, Autoimmune↗