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Biomedical subjects

H Iida

Publications and source records attributed to H Iida.

At least 649 records · Page 36Linked to original sources
PubMed1976

Purification of host DNA synthesis-suppressing factor (DSF) produced by infection with measles virus.

Host DNA synthesis-suppressing factor (DSF) produced into culture fluid of cloned HeLa cells (HeLa C-9) infected with a small plaque variant of Toyoshima strain of measles virus was purified by precipitation with ammonium sulfate, chromatography on CM-cellulose and DEAE-cellulose, and gel-filtration on Sephadex G-100 and G-200. The specific activity of the finally purified DSF was 302 units/mg of protein representing approximately 300-fold purification. The molecular weight of DSF was estimated to be about 55 000. By isoelectric focusing, two kinds of DSF having isoelectric points of 4.24 and 5.24 were detectable. The purified DSF was able to suppress host DNA synthesis of HeLa cells, continuous human lymphoid cells (NC-37), mouse L cells and Meth-A cells derived from an ascitic tumor of the mouse. The activity of the purified DSF was inactivated by heating at 56 C for 30 min or by treatment with trypsin.

DNA↗
PubMed1976

Antigenicity of converting phages obtained from Clostridium botulinum types C and D.

Phage conversion of toxigenicity in Clostridium botulinum types C and D was accomplished by using nontoxigenic strains and phages purified from plaques. Although the morphology of the converting phages seemed to be the same, they were divided into three groups on the basis of their conversion spectrum. The first group consists of phages obtained from toxogenic strains C-Stockholm and C-468. The second group consists of phages from strains D-1873 and C-203. The third group consists of phages from strains D-South African and D-4947. These converting phages were also classified into the same three groups by a neutralization test with specific antiphage sera. Cross-neutralization, however, was observed between phages belonging to group 1 and group 2,by both the neutralization test of converting ability and by a plaque experiment in which the surviving rates of phages were calculated after treatment with each antiphage serum. The antigenic differences among these converting phages should probably comprise one of the reasons for the existence of the specific infection spectrum in C. botulinum types C and D.

Antigens, Viral↗
PubMed1976

Phage conversion to hemagglutinin production in Clostridium botulinum types C and D.

Five toxigenic strains of Clostridium botulinum types C and D were incubated at 37 degrees C for 7 days in 15 ml of the following media: LYG medium, cooked-meat medium, egg meat medium, and N-Z-amine medium. The supernatants of these cultures were tested for hemagglutinin production with 1% erythrocytes obtained from mice, guinea pigs, chickens, sheep, monkeys, and humans. Four toxigenic strains produced hemagglutinin. The highest hemagglutinin titer was obtained with a combination of human erythrocytes and cultures incubated in LYG medium. When the same experiment was carried out with many nontoxigenic strains, hemagglutination was observed in only one strain, C-N71. Strains producing hemagglutinin also produced phages. The phages obtained from toxin- and hemagglutinin-producing strains converted nontoxigenic indicator strains to produce both toxin and hemagglutinin. The phage obtained from a toxin-positive hemagglutinin-negative strain could only induce cultures to produce toxin, and the phage from a toxin-negative hemagglutinin-positive strain could only induce production of hemagglutinin. These studies suggest that the production of hemagglutinin by C. botulinum types C and D is governed by bacteriophages and that hemagglutinin production can be transmitted separately or concomitantly with toxin production.

Bacteriophages↗
PubMed1975

Studies on tetrahymena membranes. Modification of surface membrane lipids by replacement of tetrahymanol by exogenous ergosterol in Tetrahymena pyriformis.

Tetrahymena pyriformis WH-14 cells were grown in the medium supplemented with ergosterol (1 mg/100 ml) and the effects of replacement of tetrahymanol by ergosterol upon the lipid composition in the surface membranes (cilia and pellicles) were examined. 1. By scanning and freeze-etch electron microscopy it was suggested that exogenous ergosterol would be inserted into the lipid regions in the surface membranes. Although freeze-etched faces of filipin-treated membranes containing the native tetrahymanol showed a random distribution of 85-a protein particles, the ergosterol-replaced membranes after the same polyene treatment revealed the marked ultrastructural alterations on the fracture faces. 2. The replacement of tetrahymanol in membranes by ergosterol induced a profound alteration in the phospholipid class composition and a marked increase in phosphatidylethanolamine with a compensatory decrease in phosphatidylcholine and 2-aminoethylphosphonolipid. 3. There are significant and quantitative but not qualitative changes in the fatty acid composition of total lipids from the ergosterol-replaced membranes. There are also increases in saturated and decreases in unsaturated fatty acids. Phosphatidylethanolamine acyl chains particularly become more saturated, as compared with two other phospholipids, in ergosterol-replaced pellicles. This increase in saturation is due to an appreciable increase in C14:0, C16:0 and iso-C17:0, and a decrease in C18:1(delta9), C18:2(delta9,12) and C18:3(delta6,9,12). 4. These results suggest that profound alterations in phospholipids as well as in their fatty acyl chains are required to modify the overall membrane lipid composition for the maintenance of proper membrane fluidity. Our data would also support the thesis that polat head groups are involved in the membrane lipid organization and that sterols interact selectively with phospholipid molecules containing the appropriate fatty acyl chain composition in biological membranes.

Acetates↗
PubMed1975

Observations on nonconverting phage, c-n71, obtained from a nontoxigenic strain of Clostridium botulinum type C.

A nontoxigenic mutant (C-N71) obtained from a toxigenic strain of Clostridium botulinum type C, Stockholm, with nitrosoguanidine treatment was found to be lysogenic by the lysis test. Although the filtrate of a passaged lysate of this nontoxigenic but lysogenic strain, C-N71, lysed cells of the nontoxigenic strain C-AO2 equally as well as the converting phage c-st obtained from the strain C-Stockholm, it did not convert C-AO2 to the toxigenic state. The lysis spectrum of this filtrate was the same as that of the c-st phage. The ability of the filtrate to lyse the indicator cells, C-AO2, was destroyed neither by trypsin nor DNase but was inactivated by heat treatment at 80 C for 10 min. This suggested that the agent which caused lysis was not boticin but probably a phage. An electron micrograph of the complete phage, c-n71, which was similar in morphology to that of the c-st phage was obtained from the filtrate of strain C-N71. Anti-c-n71 phage rabbit serum neutralized both the lytic and the converting activities of the c-st phage. These findings strongly suggest that the c-n71 phage is a mutant of the c-st phage which lacks the gene controlling production of botulinum type C toxin.

Acridines↗
PubMed1975

Stimulation of non-histone chromosomal protein synthesis in simian virus 40-infected simian cells.

The pattern of synthesis of non-histone chromosomal proteins in simian virus (SV) 40-infected African green monkey kidney cells was analyzed by polyacryl-amide gel electrophoresis to see whether the changes in chromosomal protein metabolism are involved in the viral-induced synthesis of cellular DNA and mRNA. During the prereplicative phase of infection, the rate of histone synthesis was decreased until 15 h postinfection, whereas that of non-histone protein synthesis was increased after 5 h postinfection and reached a maximum at 10 to 15 h postinfection when viral-induced synthesis of cellular DNA and mRNA began to be observed. Stimulation of non-histone protein synthesis was also observed in the infected cells treated with cytosine arabinoside and was dependent on the multiplicity of infection. Stimulation occurred in almost all species of non-histone proteins. These results suggest that the stimulation of non-histone protein synthesis is caused by an early SV40 function and occurs prior to the viral-induced synthesis of cellular DNA and mRNA. During the replicative phase of infection, a marked increase in the rate of synthesis was observed in the non-histone proteins with molecular weights of about 48,000, 35,000, and 23,000, which were subsequently found to be SV40 capsid proteins.

Animals↗