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Biomedical subjects

F Tamura

Publications and source records attributed to F Tamura.

At least 37 records · Page 2Linked to original sources
PubMed1988

Donor core-cooling provides improved static preservation for heart-lung transplantation.

Twenty-three dairy calves underwent heart-lung allotransplantation after donor organs were procured using either donor core-cooling through cardiopulmonary bypass (CPB) or pulmonary artery flush (PAF) to assess which method provides optimal graft preservation. In Groups 1 (control) and 2, donors were cooled to 15 degrees C on CPB and organs were either immediately transplanted (Group 1) or stored in saline solution (4 degrees C) for 4 hours (Group 2) prior to transplantation. In Group 3, donors were pretreated with prostaglandin E1 prior to PAF with modified Euro-Collins solution. Organs were stored in saline solution (4 degrees C) for 4 hours and were then transplanted. Acute cardiopulmonary function following transplantation was assessed by the ratio of end-systolic pressure to end-systolic dimension, extravascular lung water (EVLW), lung compliance, arterial oxygenation, and lung biopsy. Cardiac function after the transplantation procedure was similar in all groups, but EVLW values and lung biopsy scores were worse after PAF. Arterial O2 tension appeared lower after PAF, but not significantly so. Core-cooling provides superior static preservation and thus improved graft function in the acute bovine model.

Animals↗
PubMed1987

The Escherichia coli dnaJ mutation affects biosynthesis of specific proteins, including those of the lac operon.

Temperature-sensitive dnaJ mutants of Escherichia coli showed a thermosensitive defect in the synthesis of beta-galactosidase. Synthesis of the lac mRNA was greatly reduced at the restrictive temperature. The mutants were also conditionally defective in the synthesis of a subset of membrane proteins such as succinate dehydrogenase, whereas the synthesis of anthranilate synthetase, encoded by trpED, as well as that of most cellular proteins, was unaffected at the restrictive temperature. The defect was specific for the dnaJ mutants among several dna mutants which are known to be involved in the initiation of DNA synthesis: dnaK, dnaA, and dnaB mutants synthesized each of these proteins normally even at the restrictive temperature. At the restrictive temperature, growth of the dnaJ mutants was arrested at a specific stage of the cell cycle.

Anthranilate Synthase↗
PubMed1986

Nucleotide sequence of the Escherichia coli dnaJ gene and purification of the gene product.

The dnaJ and dnaK genes are essential for replication of Escherichia coli DNA, and they constitute an operon, dnaJ being downstream from dnaK. The amount of the dnaJ protein in E. coli is substantially less than that of the dnaK protein, which is produced abundantly. In order to construct a system that over-produces the dnaJ protein, we started our study by determining the DNA sequence of the entire dnaJ gene, and an operon fusion was constructed by inserting the gene downstream of the lambda PL promoter of an expression vector plasmid, pPL-lambda. Cells containing the recombinant plasmid produced dnaJ protein amounting to 2% of the total cellular protein when cells were induced. The overproduced protein was purified, and Edman degradation of the protein indicated that the NH2-terminal methionine was found to be processed. From the DNA sequence of the dnaJ gene, the processed gene product is composed of 375 amino acid residues, and its molecular weight is calculated to be 40,975.

Amino Acid Sequence↗
PubMed1984

The E. coli divE mutation, which differentially inhibits synthesis of certain proteins, is in tRNASer1.

The temperature-sensitive divE mutant of Escherichia coli cannot synthesize certain membrane and cytoplasmic proteins at a non-permissive temperature. Growth of the mutant cells is arrested at a specific stage of the cell cycle when exposed to the non-permissive conditions, suggesting that the divE mutant possesses a defect in cell division control. From sequence determination of a cloned 1.35-kbp DNA fragment that complements the temperature-sensitive divE42 mutation, we characterized two genes in the segment ; one for tRNASer1 and the other for a 23 500 dalton protein. In parallel experiments we cloned the homologous 1.35-kbp DNA fragment from the divE42 mutant and determined its entire nucleotide sequence. Comparison of the two sequences showed that the mutation site is located not in the protein gene, but in the tRNA gene, where A10 is replaced by G10 in the D-stem. Lambda transducing phages carrying the subcloned tRNASer1 gene complemented the divE42 mutation, thereby confirming the conclusion obtained from sequence analyses of the fragments. This finding indicates that tRNASer1 is specifically involved in regulation of cell cycle-specific protein synthesis, coupled with an important step in the process of cell division, or that usage of serine tRNA is functionally specific for the biosynthesis of certain proteins.

Bacterial Proteins↗
PubMed1983

A new technique in echocardiology: B-mode to M-mode transformation.

In conventional two-dimensional Echocardiography with sector scanning, M-mode is simultaneously displayed on TV-monitor as the time based ultrasound signals. With conventional system, one end of the cursor-line in B-mode image which indicates the beam direction of M-mode, is always fixed at the point corresponding to the transducer tip. This system has the capability to transform B-mode to M-mode images in any desired direction. However, the time resolution in M-mode is limited to about 33 milli-seconds.

Biometry↗
PubMed1980

Organization of unc gene cluster of Escherichia coli coding for proton-translocating ATPase of oxidative phosphorylation.

The proton-translocating ATPase (F1-F0) of oxidative phosphorylation (ATP phosphohydrolase, EC 3.6.1.3) is coded for by a set of structural genes comprising the unc operon in Escherichia coli. We have analyzed several new transducing phages and plasmids carrying various lengths of the DNA segments of the unc operon by complementation assay using 14 new unc- mutants and representatives of previously described strains which were made available to us. Transducing phages carrying parts of the unc gene cluster were isolated: lambda uncA-9 and lambda glmS phages converted only some of the unc- mutants to the Unc+, as determined by complementation assays. A new hybrid plasmid (pMCR533) carrying part of the unc operon was constructed by inserting the HindIII fragment of lambda asn-5 DNA (a phage carrying the entire unc operon) into the unique HindIII site of pBR322. This plasmid transformed eight unc- strains to Unc+, including uncB402 and uncA401, but did not complement uncD11 or four other strains. Two minichromosomes which carry the E. coli replication origin were also tested: plasmid pNH05 transformed the uncB402 but not the uncA401 strain to Unc+, whereas plasmid pMCF1 transformed none of the mutants tested. Analysis of the DNAs from these transducing phages and plasmids with restriction endonucleases suggested that all of the structural genes for the F1-F0 complex are localized within a DNA segment of approximately 4.5 megadaltons containing two EcoRI sites. The approximate locations of the unc- mutations were mapped on this DNA segment.

Adenosine Triphosphatases↗
PubMed1979

Specialized transducing phage lambda carrying the genes for coupling factor of oxidative phosphorylation of Escherichia coli: increased synthesis of coupling factor on induction of prophage lambda asn.

Studies were made of the synthesis of the coupling factor complex (F1--F0) of oxidative phosphorylation after prophage induction of a set of Escherichia coli strains lysogenic for defective transducing phage lambda asn, lambda uncA, or lambda bglC. The transducing phages had been isolated from a strain of E. coli carrying prophage lambda cI857 S7 within the bglB gene located near the unc gene cluster [Miki, T., Hiraga, S., Nagata, T. & Yura, T. (1978) Proc. Natl. Acad. Sci. USA 75, 5099--5103]. When lysogenic cells carrying lambda asn and lambda cI857 S7 were induced at high temperature, synthesis of the F1-ATPase portion of the complex increased to severalfold that of the noninduced cells. In contrast, no increase was observed upon thermoinduction of cells carrying lambda uncA or lambda bglC. The number of membrane sites that could bind purified F1-ATPase also increased significantly upon induction by lambda asn but not by lambda uncA or lambda bglC. In addition, F1-depleted membranes prepared from lambda asn-induced bacteria required more dicyclohexylcarbodiimide to seal the proton pathway than did those from noninduced bacteria. These results strongly suggest that lambda asn carries a set of bacterial genes coding for all the F1 polypeptides (the alpha, beta, gamma, delta, and probably the epsilon subunits) and at least some of the genes involved in formation of F0 polypeptides. Although lambda uncA carries the structural gene (uncA) for the alpha subunit of F1-ATPase, it apparently does not carry the whole set of F1--F0 genes.

Adenosine Triphosphatases↗