Search PubMed⌕ Search

Biomedical subjects

M Ohtsubo

Publications and source records attributed to M Ohtsubo.

66 records · Page 4Linked to original sources
PubMed1988

Ouabain sensitivity of a chimeric alpha subunit (Torpedo/rat) of the (Na,K)ATPase expressed in Xenopus oocyte.

A cDNA for a chimeric alpha subunit of the (Na,K)ATPase was constructed and expressed in Xenopus oocytes in order to elucidate structural features involved in ouabain sensitivity. A chimeric alpha subunit, in which the N-terminal 165 amino acid sequence of ouabain-resistant rat alpha subunit, including the first two transmembrane segments (M1 and M2), was replaced by a sequence from the corresponding region of ouabain-sensitive Torpedo alpha subunit, was ouabain-sensitive, suggesting that the M1-M2 junction is a site responsible for ouabain sensitivity of the (Na,K)ATPase.

Amino Acid Sequence↗
PubMed1988

The gene coding a ubiquitin-activating enzyme may locate on X chromosome.

tsBN75 cells which have a ts defect in the S phase have a mutation linked to the gene of hypoxanthine phosphoribosyl transferase and cannot complement ts85 cells which have a ts defect in the ubiquitin-activating enzyme. The ubiquitin-activating enzyme may be required for completion of the S phase.

Animals↗
PubMed1988

Simple and effective method of electroporation for introduction of plasmid and cosmid DNAs to mammalian cells.

We have established a simple and efficient method of electroporation applicable to gene transfer in mammalian cells. It uses a single decaying pulse of around 1 ms at room temperature in the medium such as Saline G appropriate for repair of pulse-induced pores in the plasma membrane. Many types of cells (both floating and adherent) could be transformed efficiently by the electric field strengths between 1-2 kV/cm. For instance P3U1, mouse myeloma cell, could be transformed by a pulse at 1.2 kV/cm with the frequency of 10(-2) per viable cells and with survivals of 90%. We have applied these conditions to transform tsBN2 cell line of BHK21/13 by a cosmid clone (approximately 45 kb) carrying the human gene complementing to tsBN2 mutation. Significant levels of transformation were observed for this gene. Since this gene can only work as a whole size (approximately 30 kb), the results show that electroporation is useful to introduce cosmid or possibly genomic DNA to mammalian cells.

Animals↗
PubMed1987

In vitro mutated beta subunits from the F1-ATPase of the thermophilic bacterium, PS3, containing glutamine in place of glutamic acid in positions 190 or 201 assembles with the alpha and gamma subunits to produce inactive complexes.

Using site-directed mutagenesis, Glu-190 or Glu-201 of the beta subunit of the F1-ATPase from the thermophilic bacterium PS3 were replaced with glutamine. It was possible to reconstitute complexes of the mutated beta subunits with alpha and gamma subunits, but the complexes did not have ATPase activity. It is concluded that carboxylic acid side chains of Glu-190 and Glu-201 of the beta subunit are essential for catalytic activity of F1-ATPase.

Bacteria↗
PubMed1987

Isolation and characterization of the active cDNA of the human cell cycle gene (RCC1) involved in the regulation of onset of chromosome condensation.

The human RCC1 gene was cloned after DNA-mediated gene transfer into the tsBN2 cell line, which shows premature chromosome condensation at nonpermissive temperatures (39.5-40 degrees C). This gene codes for a 2.5-kb poly(A)+ RNA that is well conserved in hamsters and humans. We isolated 15 cDNA clones from the Okayama-Berg human cDNA library, and found two that can complement the tsBN2 mutation with an efficiency comparable to that of the genomic DNA clone. The base sequences of these two active cDNA clones differ at the 5' proximal end, yet both have a common open reading frame, encoding a protein of 421 amino acids with a calculated molecular weight of 44,847 and with seven homologous repeated domains of about 60 amino acids. This human RCC1 gene was located to human chromosome 1 using sorted chromosomal fractions.

Animals↗
PubMed1986

Molecular cloning of a human gene that regulates chromosome condensation and is essential for cell proliferation.

The tsBN2 cell line, a temperature-sensitive (ts) mutant of baby hamster kidney cell line BHK21/13, seems to possess a mutation in the gene that controls initiation of chromosome condensation. At the nonpermissive temperature (39.5 degrees C), the chromatin of tsBN2 cells is prematurely condensed, and the cells die. Using tsBN2 cells as a recipient of DNA-mediated gene transfer, we investigated a human gene that is responsible for regulation of chromosome condensation and cell proliferation. We found that the human gene complementing the tsBN2 mutation resides in the area of the 40- to 50-kilobase HindIII fragment, derived from HeLa cells. Based on this finding, we initiated cloning of a human gene complementing the tsBN2 mutation. From lambda and cosmid libraries carrying partial digests of DNA from the secondary transformants, the 41.8-kilobase HindIII fragment containing the human DNA was isolated. The cloned human DNA was conserved in ts+ transformants through primary and secondary transfections. Two cosmid clones convert the ts- phenotype of tsBN2 cells to ts+ with more than 100 times a higher efficiency, compared with cases of transfection with total human DNA. Thus, the cloned DNA fragments contain an active human gene that complements the tsBN2 mutation.

Cell Cycle↗
PubMed1985

Hepatitis associated with allopurinol.

When adverse reactions occur, it is important to identify the etiologic drug. We describe a case of hepatitis associated with allopurinol. A 66-year-old female was admitted for rehabilitation of a cerebral hemorrhage on September 11, 1981. Allopurinol, clofibrate, and baclofen were administered. Severe hepatitis developed on November 13. The clinical laboratory data returned to normal on November 30. Challenge tests were conducted on clofibrate, allopurinol, and baclofen. The challenge test was positive after the administration of allopurinol. Allopurinol hepatitis is most likely a hypersensitivity reaction, as is suggested by the symptoms of eosinophilia and rash. Renal dysfunction may predispose one to develop hepatitis associated with allopurinol.

Aged↗
PubMed1985

[Clinical studies with cefoperazone in the biliary disease].

The concentration of cefoperazone (CPZ) in serum and bile was estimated after intravenous drip infusion of 1 g of the drug in 11 patients, who have performed cholecystectomy, choledocholithotomy and T-tube drainage for gallstone diseases. Administration of cefazolin (CEZ) 1 g was compared by the cross over method. After 1 g intravenous drip infusion of CPZ, the mean serum concentration was 88.3 +/- 24 micrograms/ml at 1 hour, 52 +/- 11.7 micrograms/ml at 2 hours and 36.5 +/- 10 micrograms/ml at 4 hours. The maintenance period of serum concentration was inclined to be longer in CPZ than in CEZ. After 1 g intravenous drip infusion of CPZ, the mean bile concentration reached to 810 +/- 459 micrograms/ml in 2 hours and it was maintained as high as 562 +/- 319 micrograms/ml even after 4 hours. On the other hand, after 1 g intravenous drip infusion of CEZ, the mean bile concentration was only 28.7 +/- 26 micrograms/ml in 1 hour and was low level in the progress. As compared with the highest concentration of CPZ and CEZ in same patient, the mean bile concentration of CPZ (942 +/- 525 micrograms/ml) was about 30 times higher than that of CEZ (28.6 +/- 26.3 micrograms/ml). There was no difference in the group of Gram-positive cocci between minimum inhibitory concentration (MIC) of CPZ and that of CEZ. While MIC of CEZ in the group of Gram-negative bacilli was from 0.78 to over 400 micrograms/ml, MIC of CPZ in that group was from 0.10 to 50 micrograms/ml. The value in CPZ was lower than that in CEZ at all strains. No side effects was seen in all patients.

Adult↗
PubMedDate not supplied

Receptor-mediated gene delivery using the Fab fragments of anti-epidermal growth factor receptor antibodies: improved immunogene approach.

We previously developed the "immunogene" approach toward cancer gene therapy using epidermal growth factor receptor (EGFR)-mediated endocytosis. Here, we describe an improved immunogene system, in which the antigen-binding (Fab) fragments of the monoclonal antibody (Ab) B4G7 against the human EGFR were conjugated with poly-L-lysine to form a gene delivery vehicle (designated Fab "immunoporter"). Within 12 hours, the beta-galactosidase beta-gal) gene was transferred via the Fab immunoporter to virtually all of the nuclei of human squamous carcinoma A431 cells that overproduce the EGFR, and the beta-gal enzyme activity was detected within 24 hours and retained for more than 3 days. The beta-gal gene was not transferred into human and mouse cells that were deficient in EGFRs, but it was delivered if those mouse cells were transformed with human EGFR genes. Beta-gal gene transfer via the Fab immunoporter was inhibited by pretreatment with excess amounts of the Fab fragment. The transfer efficiency of the beta-gal gene to A431 cells via the Fab immunoporter was approximately 2%, which is as high as the lipofection method and 20- to 100-fold higher than the whole Ab immunoporter. The transfer of the herpes simplex virus thymidine kinase gene into A431 tumor cells as a form of the thymidine kinase/Fab immunogene was successful, and subsequent treatment with ganciclovir induced remarkable suicide effects which conferred 1000-fold higher drug sensitivity. Thus, the Fab immunogene was substantially improved with regard to the whole Ab immunogene and could be used as a potent gene transfer vehicle for the in vivo targeting of EGFR-hyperproducing tumor cells.

Animals↗