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Biomedical subjects

K Matsubara

Publications and source records attributed to K Matsubara.

At least 415 records · Page 23Linked to original sources
PubMed1988

Electron microscopy of hepatitis B virus core antigen expressing yeast cells by freeze-substitution fixation.

We have used the freeze-substitution fixation technique for electron microscopy of yeast cells that express the hepatitis B virus core antigen (HBcAg) following transformation with the cloned gene. Abundant spherical particles were found within the transformed cells. These particles had a uniform size and shape, measured about 21 nm in diameter, had electron-lucent centers, and consisted of many subunits. They were localized in both the cytoplasm and the nucleus. None of these particles was found in the cells of the parent strain. Comparison of the HBcAg particles isolated from the yeast cells and the particles within the yeast cells demonstrated that the 21-nm particles were in fact ultrastructurally superimposable on HBcAg. Thus, the HBcAg particles within the yeast cells were similar to the HBcAg particles in human liver tissues infected with hepatitis B virus, not only in their size and appearance, but also in their intracellular localization. These results suggest that the yeast cell has the same machinery for synthesis and intracellular translocation of the HBcAg polypeptides as the human cell.

Animals↗
PubMed1987

Production of human thyroid-stimulating hormone in Chinese hamster ovary cells.

Human thyroid-stimulating hormone (hTSH) has been produced in Chinese hamster ovary (CHO) cells co-transformed with two plasmids: one carrying the alpha subunit cDNA with mouse dihydrofolate reductase gene and the other carrying hTSH beta subunit cDNA. Each cDNA was driven to expression under the control of SV40 early promoter. hTSH and its alpha subunit were secreted into culture media, and their secretion increased with exposure of the cells to increasing concentrations of methotrexate. Gel filtration analysis revealed that the molecular size of the hTSH was the same as that of natural hTSH. Furthermore, the CHO cell-produced hTSH elevated the cyclic AMP level in the rat thyroid cell line FRTL-5 in the same manner as natural hTSH does.

Animals↗
PubMed1987

Primary structure of human pancreatic secretory trypsin inhibitor (PSTI) gene.

The human pancreatic secretory trypsin inhibitor (PSTI) gene was isolated from a human gene library. Restriction endonuclease mapping and DNA sequencing analysis revealed that this gene is approximately 7.5 kb long and is separated into four exons by three introns. The gene has multiple transcription start points and examination with a single-laser cell-sorter showed that it is located on chromosome 5.

Base Sequence↗
PubMed1987

Expression of pancreatic secretory trypsin inhibitor gene in neoplastic tissues.

Expression of the human pancreatic secretory trypsin inhibitor (PSTI) gene was examined in 24 cases of neoplastic tissues by Northern blot analyses. In three cases of lung adenocarcinoma and one case of sigmoid colon polyp, we detected transcripts which hybridized to the human PSTI cDNA probe. cDNA libraries were constructed using mRNAs of the two PSTI-positive tumor tissues. Two PSTI cDNA clones were obtained from each sample. Sequencing analyses showed that they were completely identical with that of pancreatic PSTI cDNA which had been reported [(1985) Biochem. Biophys. Res. Commun. 132, 605-612]. Southern blot analyses showed that the elevated expression of PSTI in neoplastic tissues was accompanied by neither PSTI gene amplification nor rearrangements.

Adenocarcinoma↗
PubMed1987

A systematic regional study of brain salsolinol levels during and immediately following chronic ethanol ingestion in rats.

Regional contents of salsolinol and catecholamines in the brain of normal and ethanol-treated rats were studied. Male Sprague Dawley rats were given ethanol solution as sole drinking fluid for 3, 4, 5 or 6 months. Salsolinol determined by gas chromatography mass spectrometry was found to be present in the hypothalamus and the striatum of control rats. The levels of salsolinol in these regions increased significantly by long-term ethanol drinking and rapidly decreased to control levels following its removal. Salsolinol levels in other regions of rat brain were extremely low or negative and unaltered upon chronic ethanol treatment. In ethanol-treated rats the hypothalamic salsolinol, although generally higher than in the striatum, increased along with the ethanol exposure, whereas the striatal salsolinol was constant during those periods of study. Brain dopamine (DA) and norepinephrine contents remained unaltered during and immediately after chronic ethanol treatments. No correlation of salsolinol levels with DA contents or blood ethanol concentrations was observed. The occurrence of salsolinol in selected areas of rat brain with lack of changes in catecholamine level but as a result of an in vivo formation by long-term ethanol drinking was considered to be due to an alteration of acetaldehyde metabolism in the liver and brain.

Animals↗
PubMed1987

Molecular cloning of the S-antigen cDNA from bovine retina.

S-antigen is the major component of the soluble proteins in the retina and the pineal, and is thought to play a regulatory role in the visual cycle. It induces experimental autoimmune uveitis (E.A.U.) in various species of laboratory animals. We have cloned the cDNA of S-antigen from bovine retina, containing the entire coding region, and determined its nucleotide sequence. The sequence consists of a 1212 nucleotide region that specific the amino acid sequence, a 368 nucleotide 5' untranslated region and a 80 nucleotide 3' untranslated region. The previously reported partial amino acid sequence defining the carboxy terminal moiety of the polypeptide, fits into our sequence. Homologies were found between the predicted amino acid sequence of S-antigen and that of alpha transducin.

Amino Acid Sequence↗
PubMed1987

Direction of transcription affects the replication mode of lambda in an in vitro system.

A set of artificial circular plasmids, named plasmoids, was constructed. They are about 1 kb in size and consist of a 178 bp lambda dv minimal DNA replication origin (ori) which has four direct repeats and the A + T-rich region conferring polarity to the ori fragment, a 775 bp DNA segment that codes for the CAT amino acid sequence and the 99 bp lac promoter (plac). They carry no other functional genes or genetic sites. The constructions involved various combinations of relative orientations of these components. These molecules do not replicate in vivo because they lack genes coding for initiation proteins, but they do replicate in an in vitro system (Fuller et al. 1981), and can be used for studies of interactions between transcription and replication. In these plasmids, major transcription starts from the strong plac, and some weak unscheduled transcription starts from several other initiation sites. The major RNA synthesis was found to interfere with the unscheduled RNA synthesis, which was occurring on the opposite strand. The most active replication took place when the major RNA synthesis went through the lambda origin region in the direction which occurs naturally in the lambda genome. Under these conditions, DNA synthesis going against such transcription was less than that going along with the major transcription. When RNA synthesis through the lambda origin region was in the opposite direction, DNA synthesis in the same direction was about half of that observed in the above case, whereas that going against transcription was very weak.

Bacteriophage lambda↗
PubMed1987

Replication of mini-F plasmid in vitro promoted by purified E protein.

An in vitro system for replication of mini-F plasmid DNA was constructed. This system consists of an ammonium sulfate fraction II (Fuller et al. 1981) from Escherichia coli extract, exogenously added purified E protein encoded by mini-F plasmid, and mini-F DNA in a closed circular form. Experiments with this system showed that the 217 bp DNA region which contains the A + T rich cluster and the four 19 bp direct repeats responsible for incB incompatibility is essential for mini-F DNA replication.

Bacterial Proteins↗
PubMed1987

Revision of consensus sequence of human Alu repeats--a review.

Nucleotide sequences of 50 human Alu repeats and their flanking regions are presented together with the consensus sequence based on the literature and our findings. The results indicate the need for some revisions of the Alu consensus sequence published by Deininger et al. (1981). Most nucleotide substitutions among the Alu members are transitions, rather than transversions. The Alu sequence seems to consist of 'conserved' regions and 'variable' regions. The conserved regions consist of a 25-bp region between nt positions 23 and 47 and a 16-bp region between nt positions 245 and 260. The 16-bp region corresponds to the region of 7SL RNA that is claimed to fold and become paired with the internal promoter sequence. Two A-rich regions, one located at the right end of the first monomer and the other at the right end of the second monomer, are variable. No defined property was found with direct repeats flanking the Alu repeats.

Base Sequence↗
PubMed1987

Primary structure of human pancreatic alpha-amylase gene: its comparison with human salivary alpha-amylase gene.

We have determined the entire structure of the human pancreatic alpha-amylase (Amy2) gene. It is approx. 9 kb long and is separated into ten exons. This gene (amy2) has a structure very similar to that of human salivary alpha-amylase (Amy1) gene [Nishide et al. Gene 41 (1986a) 299-304] in the nucleotide sequence and the size and location of the exons. The major difference lies in the fact that amy1 has one extra exon on the 5' side. Other differences are at the 5' border of exon 1 and the 3' border of exon 10. The close similarity of these two genes, as compared with mouse pancreatic and salivary amylase genes, suggests that during evolution, the divergence into the two amylase genes may have occurred after the divergence of mice and man.

Amino Acid Sequence↗
PubMed1987

Purification of hepatitis B virus gene X product synthesized in Escherichia coli and its detection in a human hepatoblastoma cell line producing hepatitis B virus.

A fused gene containing 94% of the hepatitis B virus (HBV) open reading frame X was expressed in Escherichia coli, and its 17-kDa product was purified by ion-exchange chromatography. Antibody elicited against the X-gene product reacted with materials proximal to the nuclear membrane of a human hepatoblastoma cell line producing HBV particles. No such reaction was observed with the same cell line that did not produce HBV particles.

Carcinoma, Hepatocellular↗