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Biomedical subjects

K Oda

Publications and source records attributed to K Oda.

At least 559 records · Page 31Linked to original sources
PubMed1985

Weakly basic amines inhibit the proteolytic conversion of proalbumin to serum albumin in cultured rat hepatocytes.

Effects of weak amines on the proteolytic conversion of proalbumin to serum albumin were studied in primary culture of rat hepatocytes. In control culture proalbumin was converted to serum albumin before discharge into the medium. However, in the presence of chloroquine the conversion to serum albumin was inhibited and proalbumin per se was released into medium. A similar inhibition of the processing was also observed in the presence of other amines such as methylamine and NH4Cl. Thus weak amines mimic the carboxylic ionophore monensin with regard to the effect on proalbumin conversion [Oda & Ikehara (1982) Biochem. Biophys. Res. Commun. 105, 766-772]. Since proteolytic conversion of proalbumin is believed to occur at the Golgi complex, these results suggest that weakly basic amines perturb the Golgi complex in addition to lysosomes and endosomes.

Amines↗
PubMed1985

Transcription of the human adenovirus E1a gene in Saccharomyces cerevisiae.

The early region 1a (E1a) and its flanking sequences of human adenovirus type 5 (Ad5) have been cloned in the yeast-Escherichia coli shuttle vector YEp13 and transferred into the yeast Saccharomyces cerevisiae. The E1a-specific RNAs were produced in the transformed yeast cells. The 5' ends of these transcripts were capped but were lacking 10 to 45 nucleotides from the 5' end of the proper E1a mRNA. These transcripts terminated approx. 1000 nucleotides downstream from the proper 3' end. No splicing of the E1a-specific RNA could be detected in the yeast cells.

Adenoviruses, Human↗
PubMed1985

Amino acid sequence of Streptomyces metallo-proteinase inhibitor from Streptomyces nigrescens TK-23.

Streptomyces Metallo-Proteinase Inhibitor (S-MPI) consists of 102 amino acid residues, including one methionine and two disulfide bridges. The complete amino acid sequence of S-MPI, including two disulfide bridges, was determined by sequencing of tryptic and chymotryptic peptides of two fragments obtained by cyanogen bromide cleavage followed by reduction and S-pyridylethylation of the protein. Incubation of the inhibitor with thermolysin slowly cleaved one peptide bond, Cys(64)-Val(65), which might be a reactive site of S-MPI.

Amino Acid Sequence↗
PubMed1985

Effects of proteinase inhibitors on preimplantation embryos in the rat.

Proteinase inhibitors of microbial origin were injected into the uterine horns of mated rats at 14:00 h on Day 5 of pregnancy (spermatozoa in vaginal smear = Day 1), and 5 or 6 h later the embryos were flushed from the horns and examined. Chymostatin and alpha-MAPI, inhibitors of chymotrypsin-like serine proteinase and thiol proteinases, as well as thiolstatin, an inhibitor of thiol proteinases, significantly inhibited embryo growth. The inhibitory activity of alpha-MAPI on embryonic growth was distinctly greater than that of thiolstatin, although the ID50 values of the two inhibitors to papain are similar. Antipain and leupeptin which are inhibitors of trypsin-like and thiol proteinases, and talopeptin, an inhibitor of metal proteinases, significantly interrupted the removal of the zona pellucida from expanding blastocysts. These results suggest that (1) a chymotrypsin-like proteinase seems to be important to the growth of the embryo, (2) a thiol proteinase may participate in embryonic growth, and (3) a trypsin-like proteinase and a metal proteinase are likely to participate in zonalysis.

Animals↗
PubMed1985

The relationship between motor endplate size and muscle fiber diameter in different muscle groups of the rat.

To investigate the relationship between motor endplate size and muscle fiber diameter, analyses of 125I-alpha-bungarotoxin autoradiographs and acetylcholinesterase staining were performed in different muscle groups of the rat. These revealed 1) there is a linear correlation between endplate size and fiber diameter in each muscle group, and 2) each muscle group has a characteristic ratio of endplate size to fiber diameter; the ratios were markedly higher in extraocular muscles than in limb muscles.

Acetylcholinesterase↗
PubMed1984

Enzyme-linked immunosorbent assay for antibody against the nicotinic acetylcholine receptor in human myasthenia gravis.

Antibody against acetylcholine receptor (AChR) of human skeletal muscle was measured using enzyme-linked immunosorbent assay and found in 23 (74%) of 31 Japanese patients with generalized myasthenia gravis. In 15 patients with generalized myasthenia gravis who had not undergone thymectomy and who were not receiving adrenocorticosteroids, the antibody was found in 13 (87%). Antibody was also found in 13 (54%) of 24 patients with myasthenia gravis against AChR fractions obtained from fetal calf thymus. Based on the subunit structures of the AChR protein, the double precipitation assay using iodine 125-alpha-bungarotoxin is also capable of detecting antibody against the toxin binding site, by cross reactivity. This is among the first reports of experiments in which enzyme-linked immunosorbent assay was used to measure the antibodies in human myasthenia gravis and provides evidence of anti-AChR antibody against antigens from fetal calf thymus.

Autoantibodies↗
PubMed1984

Exacerbation of myasthenia gravis after removal of a thymoma having a membrane phenotype of suppressor T cells.

We describe a case of myasthenia gravis associated with a thymoma having a membrane phenotype of suppressor T cells, as defined by monoclonal antibodies. Thymectomy resulted in exacerbation of the disease, a drastic increase in serum acetylcholine receptor-antibody titer, and a decrease of the circulating suppressor T cell population. The findings indicate that the etiopathogenic relationship between the thymus and myasthenia gravis is variable and complex.

Adult↗
PubMed1984

Complete amino acid sequence of Scytalidium lignicolum acid protease B.

The acid protease B (SLB) of Scytalidium lignicolum was reduced and carboxymethylated and then subjected to tryptic digestion. Five fragments were isolated and some of them were further digested with alpha-chymotrypsin, thermolysin, and dilute acetic acid. The sequence analysis of these fragments and the peptides by conventional methods established the complete amino acid sequence of SLB. The enzyme was composed of 204 amino acid residues with threonine and valine as its amino- and carboxyl-termini, respectively. Locations of three disulfide bridges were also established to be Cys47-126, Cys140-163, and Cys192-201 by enzymatic fragmentation of the denatured and unmodified SLB. Only a slight homology was found in the sequences of SLB and other acid proteases hitherto reported.

Amino Acid Sequence↗