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Biomedical subjects

S Hiraga

Publications and source records attributed to S Hiraga.

At least 145 records · Page 8Linked to original sources
PubMed1989

Purification and characterization of SopA and SopB proteins essential for F plasmid partitioning.

Mini-F plasmid has the trans-acting genes sopA and sopB and the cis-acting site sopC which are essential for accurate partitioning of plasmid DNA molecules into both daughter cells. In this study, we purified independently SopA and SopB proteins, analyzed the in vitro DNA-binding activity of these proteins by the gel retardation assay, and determined the precise binding sites of DNA by the footprinting method. SopA binds to four repeated sequences (CTTTGC) located in the promoter-operator region of the sopAB operon. The SopA binding activity is enhanced by the addition of SopB protein. SopB protein itself does not bind to this DNA region. These results suggest that the complex of SopA and SopB proteins autoregulate the expression of the sopA-sopB operon. On the other hand, SopB protein binds to the sopC region, in which 12 direct repeats of 43-base pairs nucleotides exist. SopB protein recognizes the inverted repeats of 7 base pairs in each direct repeats. SopA protein does not affect the SopB binding activity to the sopC DNA segment.

Bacterial Proteins↗
PubMed1989

Involvement of DnaK protein in mini-F plasmid replication: temperature-sensitive seg mutations are located in the dnaK gene.

The seg mutants (seg-1 and seg-2) of Escherichia coli cannot support the replication of the F factor and mini-F plasmids at 42 degrees C. We cloned the wild-type E. coli chromosomal DNA fragment complementing the seg-1 and seg-2 mutations and found that both mutations were complemented by the wild-type dnaK gene coding for a heat shock protein. Transduction with phage P1 indicated that the seg-2 mutation is located at about 0.3 min in the region containing the dnaK gene in the order trpR--thrA--seg-2--leuB, consistent with the locus of the dnaK gene. Cloning and sequencing of the dnaK gene of the seg mutants showed that there was one base substitution within the dnaK gene in each mutant causing an amino acid substitution. These results indicate that the seg gene in which the seg-1 and seg-2 mutations occurred is identical to the dnaK gene. The mini-F plasmid pXX325 did not transform a dnaK null mutant to ampicillin resistance at 30 degrees C in contrast to plasmids pBR322, pACYC184 and pSC101, which did. The active dnaK (seg) gene product is therefore essential for replication of the mini-F plasmid at both 30 degrees and 42 degrees C.

Bacterial Proteins↗
PubMed1989

Purification and characterization of the sopB gene product which is responsible for stable maintenance of mini-F plasmid.

The mini-F plasmid has the trans-acting sopA, sopB genes and the cis-acting sopC DNA which are essential for plasmid partitioning. In this paper, we report the purification of the sopB gene product from extracts of cells harboring a pBR322 derivative carrying the sopB gene. The purity of the final preparation was more than 95%, as determined by densitometry. The amino acid sequence of the amino-terminal region of the protein for the 17 residues identified was identical to that predicted from the DNA sequence of the sopB gene. Therefore, it was concluded that the protein was the sopB gene product. Using anti-SopB serum, the SopB protein was detected in the cell lysates of F+, F', and Hfr strains. The SopB protein bound to the plasmid DNA of a pBR322 derivative carrying the sopC DNA segment, but not to the vector plasmid pBR322.

Bacterial Proteins↗
PubMed1989

Functional changes of aorta with massive accumulation of calcium.

The present study was undertaken to elucidate pathophysiological changes and functional alterations of the calcified artery. For this purpose, rats were treated with 500,000 units/kg vitamin D3, and tension development of isolated rat aortae was examined. Treatment of rats with vitamin D3 resulted in an increase (approx. 64-fold) in the tissue calcium. Light microscopic examination of the aorta after staining with hematoxylin-eosin and von Kossa indicated numerous plaques in the aortic media. The results indicate a massive accumulation of calcium in the aortic media. Responsiveness of the calcified tissue to norepinephrine, epinephrine, serotonin, prostaglandin F2 alpha was found to be 11-66% when compared to that of the control. Furthermore, the calcified tissue responded minimally to isoproterenol and acetylcholine, which elicited a relaxation in control aortae. Isoproterenol-induced relaxation of the calcified aorta after 100 mM KCl contracture was also diminished. In the present study we have demonstrated poor responsiveness of the calcified aorta to physiological and pharmacological substances relative to normal tissue, which implies a functional damage of the artery upon massive calcium accumulation.

Acetylcholine↗
PubMed1989

Identification of human apolipoprotein E variant gene: apolipoprotein E7 (Glu244,245----Lys244,245).

Apolipoprotein E (apoE) is one of the protein moieties of the human serum lipoproteins. Three major isoforms of apoE (apoE2, apoE3, and apoE4) and minor variant isoforms (apoE1, apoE5, and apoE7) have been detected by isoelectric focusing. In this study we have cloned the apoE7 gene from a patient with the apoE3/E7 phenotype associated with hypertriglyceridemia and diabetes mellitus. DNA sequencing revealed that the apoE7 gene has two base substitutions (G----A) changing Glu244,245----Lys244,245, compared with the apoE3 gene. The replacement of the two amino acids is consistent with the result of isoelectric focusing of the apoE7 isoprotein, which shifts to four positively charged units compared with the apoE3 isoprotein.

Amino Acid Sequence↗
PubMed1989

Molecular cloning of a human apolipoprotein E variant: E5 (Glu3----Lys3).

Two types of apoE alleles from a genomic DNA library of a subject with the apoE2/E5 phenotype have been cloned. One of these alleles encodes an apoE isoprotein having cysteine, arginine, and cysteine at positions 112, 145, and 158 of mature apoE isoproteins, respectively, indicating an epsilon apoE2 allele. The other allele encodes a different isoprotein, having cysteine, arginine, and arginine at each of the above positions, respectively. In addition, this allele has a base substitution (G----A) which causes the substitution of lysine for glutamic acid at position 3 near the NH2-terminus of the mature apoE. This allele is a new variant, the epsilon apoE5 allele.

Amino Acid Sequence↗
PubMed1989

Chromosome partitioning in Escherichia coli: novel mutants producing anucleate cells.

To study the chromosomal partitioning mechanism in cell division, we have isolated a novel type of Escherichia coli mutants which formed anucleate cells, by using newly developed techniques. One of them, named mukA1, is not lethal and produces normal-sized anucleate cells at a frequency of 0.5 to 3% of total cells in exponentially growing populations but does not produce filamentous cells. Results suggest that the mutant is defective in the chromosome positioning at regular intracellular positions and fails frequently to partition the replicated daughter chromosomes into both daughter cells, resulting in production of one anucleate daughter cell and one with two chromosomes. The mukA1 mutation causes pleiotropic effects: slow growth, hypersensitivity to sodium dodecyl sulfate, and tolerance to colicin E1 protein, in addition to anucleate cell formation. Cloning of the mukA gene indicates that the mukA1 mutation is recessive and that the mukA gene is identical to the tolC gene coding for an outer membrane protein.

Bacterial Outer Membrane Proteins↗
PubMed1989

Penicillin-binding protein 2 is essential in wild-type Escherichia coli but not in lov or cya mutants.

Penicillin-binding protein 2 (PBP2), target of the beta-lactam mecillinam, is required for rod morphology and cell wall elongation in Escherichia coli. A new temperature-sensitive PBP2 allele and an in vitro-constructed insertion deletion allele were shown to be lethal in wild-type strains, establishing that the activity of this protein is essential. Mutations in the lov or cya genes, conferring mecillinam resistance, compensated for the deleterious effect of the absence of PBP2. The resulting double mutants grew as spheres. In a cya mutant lacking PBP2, the restoration of a Cya+ phenotype by addition of cyclic AMP caused lethality and a block in cell division. These results show that in wild-type cells, PBP2 is essential for growth and division.

Acyltransferases↗
PubMed1989

[Renal failure in paroxysmal nocturnal hemoglobinuria].

UNLABELLED: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired hemolytic disorder characterized by a membrane abnormality of red cells, and characterized by two major clinical features of gross hemoglobinuria and diffuse venous thrombosis. In Japan, the present report records the first case of acute renal failure complicating PNH with treated by hemodialysis and was almost completely reversible. CASE: A 41 year-old woman was admitted for high fever (39.8 degrees C), dyspnea and clinical signs of a respiratory infection. She was started on Cefotax 1,000 mg 3 times daily. She subsequently developed acute renal failure and which treated by hemodialysis and was almost completely reversible. Following treatment of her renal failure, respiratory infection and anemia, she initially made good progress and was discharged.

Acute Kidney Injury↗
PubMed1988

Chromosomal genes essential for stable maintenance of the mini-F plasmid in Escherichia coli.

We have isolated mutants of Escherichia coli which do not support stable maintenance of mini-F plasmids (delta ccd rep+ sop+). These host mutations, named hop, were classified into five linkage groups on the E. coli chromosome. Genetic analyses of these hop mutations by Hfr mating and P1 transduction showed their loci on the E. coli genetic map to be as follows: hopA in the gyrB-tnaA region, hopB in the bglB-oriC region, hopD between 8 and 15 min, and hopE in the argA-thyA region. Kinetics of stability of the sop+ and delta sop mini-F plasmids in these hop mutants suggest that the hopA mutants are defective in partitioning of mini-F rather than in plasmid replication. The hopB, hopC, and hopD mutants were partially defective in replication of mini-F. The physical structure of the plasmid DNA was normal in hopA, B, C, and D mutants. Large amounts of linear multimers of plasmid DNA accumulated in mutants of the fifth linkage group (hopE). None of the hop mutations in any linkage group affected the normal growth of cells.

Alleles↗
PubMed1988

Minicell-forming mutants of Escherichia coli: production of minicells and anucleate rods.

The Escherichia coli minB mutant originally isolated is known to septate at cell poles to form spherical anucleate minicells. Three new minicell-producing mutants were isolated during a screening by autoradiography for chromosome partition mutants giving rise spontaneously to normal-sized anucleate cells. These min mutants were affected close to or in the minB locus. Autoradiography analysis as well as fluorescent staining of DNA showed that in addition to minicells, these strains and the original minB mutant also spontaneously produced anucleate rods of normal size and had an abnormal DNA distribution in filaments. These aberrations were not associated with spontaneous induction of the SOS response. Inhibition of DNA synthesis in these mutants gave rise to anucleate cells whose size was longer than unit cell length, suggesting that the min defect allows septation to take place at normally forbidden sites not only at cell poles but also far from poles. Abnormal DNA distribution and production of anucleate rods suggest that the Min product(s) could be involved in DNA distribution.

Autoradiography↗
PubMed1988

[A case of polycystic kidney with bilateral nephrectomy].

A 56-year-old woman in chronic hemodialysis had been suffering from uncontrollable fever for the past 7 months. Her original disease was diagnosed as familial polycystic kidney and three of her five brothers were found to have the same disease. Her chromosome was 46,XX,21P+ and laboratory examination revealed severe anemia, malnutrition, liver dysfunction, pyuria and candidiasis of urine. Abdominal echogram and CT scan revealed polycystic kidneys and multiple liver cysts. She was admitted to our hospital and was diagnosed as having pyelonephritis of the right kidney. As her condition was not improved by conservative therapy right nephrectomy was performed. One month later, spiking fever and left tenderness reappeared. Those symptoms could not be controlled by conservative therapy and left nephrectomy was performed again. Pathological examination on nephrectomized kidneys showed interstitial nephritis, hyaline degeneration and proliferative change of glomeruli, microabscess, colloid of tubules and calcification of parts of Henle's loops. Nephrectomy has been performed in 1.6 to 10.0% of polycystic kidneys due to references since 1952. Eight of the 22 polycystic kidneys (36.3%) seen at our hospital during the past 10 years have been removed.

Female↗
PubMed1988

[Lateral approach to the anterior foramen magnum tumor: report of two cases].

A procedure for lateral approach to the ventral portion of the foramen magnum and the upper cervical canal is described. The patient was placed in the lateral position and a curvilinear skin incision was made from the retoroauricular area down to the lateral neck across the sternocleidomastoid muscle, and underlying muscle layers were divided. A suboccipital hemicraniotomy and hemilaminectomies were performed with an air drill. Because the medulla and the cervical cord are displaced posteriorly by the tumor, there is no need to retract those structures and all the tumors can be removed under direct vision. This procedure was applied on the two patients with ventrally situated foramen magnum tumors; a neurenteric cyst and neurofibroma, and both of the tumors were successfully removed under direct vision. Major advantages of this approach are that there is no need for retraction of the spinal cord, and there is excellent exposure of an anteriorly located tumor, no postoperative cervical spine instability, no risk for CSF leak and infection, which effects are often found after the anterior approach. The procedure, like the posterior approach, is relatively simple.

Adult↗