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Biomedical subjects

H Taira

Publications and source records attributed to H Taira.

At least 91 records · Page 5Linked to original sources
PubMed1980

Mouse interferons: production by Ehrlich ascites tumour cells infected with Newcastle disease virus and its enhancement by theophylline.

Conditions are described for the production of 0.3 to 0.7 NIH mouse reference standard units of interferon per cell from Ehrlich ascites tumour cells cultured as monolayers and induced by infection with Newcastle disease virus (NDV). Inclusion of theophylline (6 mM) in the medium increased the interferon yield three to four times. Cells infected with NDV started to lyse at about 15 p.i., but infected, theophylline-treated cells lysed only 24 p.i. Several other methylxanthines (e.g. theobromine, caffeine and isobutylmethylxanthine) when tested a concentrations similar to that of theophylline, did not boost interferon production. Dibutyryl cyclic AMP (10(-10) to 10(-2)M) did not substitute for theophylline in increasing interferon production, and, if used together with theophylline, did not cause further enhancement.

Animals↗
PubMed1979

Structural characteristics of interferons from mouse Ehrlich ascites tumor cells.

An improved procedure for the isolation of interferons produced by mouse Ehrlich ascites tumor cells infected with Newcastle disease virus provides interferons of three size classes (33,000, 26,000, and 20,000 daltons) with specific activities between 2 and 3 x 10(9) units/mg of protein and a yield of 11 to 20%. The tryptic peptide maps of the two larger species are very similar; that of the smallest species is different, at least in part. The amino acid compositions of the three species are very close. Their NH2-terminal amino acids are identical and so are the amino acids released by carboxypeptidase A treatment. These data are consistent with the possibility that the differences in size between the three species may be due, at least in part, to unequal glycosylation.

Amino Acids↗
PubMed1978

Purification of interferon from mouse Ehrlich ascites tumor cells.

Interferon production was induced in mouse Ehrlich ascites tumor cells by infection with Newcastle disease virus. The interferon produced was purified by precipitation with ammonium sulfate, chromatography on carboxymethyl-Sephadex, treatment with blue dextran and polyethylene glycol, gel filtration on Bio-Gel P-60 and Bio-Gel P-200, chromatography on phosphocellulose, isoelectric focusing, and chromatography on octyl-Sepharose. The specific activity of the product was 1.6 x 10(9) NIH mouse interferon reference standard units/mg of protein. Electrophoresis in polyacrylamide gels in the presence of sodium dodecyl sulfate indicated that the apparent molecular weight of the interferon-active material ranged from 25,000 to 35,000. As revealed by staining the gels with Coomassie brilliant blue, the interferon activity co-migrated with the major, broad protein band. Minor, stainable bands of proteins were free of interferon activity and their apparent molecular weight was smaller than 12,000.

Animals↗
PubMed1977

Messenger RNA methylation, translation and degradation in extracts of interferon-treated cells.

Extracts from interferon-treated, not virus infected EAT cells differ in several biochemical characteristics from extracts of untreated cells. Some of these differences are manifested only if the extracts are supplemented with ds RNA and ATP. Thus, in the extracts from interferon-treated cells these supplements activate a protein kinase and an endonuclease activity as well as an inhibitor of the translation of messenger RNA. The effect of the same supplements in extracts of untreated cells is much less pronounced. Other differences between the two types of extracts do not seem to depend on the addition of ds RNA and ATP. These include an impairment of mRNA cap methylation and an inhibition of peptide chain elongation that can be overcome by the addition of tRNA. The treatment of human (HeLa S3) cells with human interferon is manifested in the cell extract similarly to the treatment of EAT cells with mouse interferon. Studies are underway to isolate and characterize the ds RNA activated enzymes and the inhibitors and to establish how the presence of these in extracts from interferon-treated cells can account for the impairment of virus replication by interferon.

Adenosine Triphosphate↗
PubMedDate not supplied

Angiotensin I-converting enzyme in human placenta.

Angiotensin I-converting enzyme (ACE, peptidyldipeptide hydrolase, kininase II, EC 3.4.15.I) from human placenta was purified 6297-fold and characterized. ACE could be extensively purified by affinity chromatography with Captopril (D-3-mercapto-2-methylpropanoyl-L-proline), an orally active antihypertensive agent and a potent inhibitor of this enzyme. Its molecular weight and subunit size were estimated to be 300 000 by high-performance gel permeation chromatography and 85 000 by sodium dodecyl sulphate gel electrophoresis, respectively, indicating its polymeric structure.

Captopril↗