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Biomedical subjects

M Fiszman

Publications and source records attributed to M Fiszman.

28 records · Page 2Linked to original sources
PubMed1974

Mode of action of acid pH values on the development of vesicular stomatitis virus.

The effect of low pH's on the development of vesicular stomatitis virus (VSV) was studied. L cells infected with VSV were incubated at pH 6.6. A 99% inhibition in the yield of infectious particles was observed by comparison with the yield at pH 7.4. Such inhibition was not due to inhibition of viral RNA synthesis, since at pH 6.6 all the known species of VSV RNA molecules were synthesized. Furthermore, all the known species of VSV proteins were also synthesized. However, no viral particles nor nucleocapsids were detected. Raising the pH to 6.9 resulted in the appearance of nucleocapsids and viral particles, although the yield of infectious virus was still inhibited by 90%. The lack of infectivity of these pH 6.9 viral particles was correlated with their inability to promote primary transcription. The hypothesis that low pH's alter the correct positioning of the viral proteins into the cell membrane is presented.

Hydrogen-Ion Concentration↗
PubMed1973

Relationship between replication of simian virus 40 DNA and specific events of the host cell cycle.

The relationship between replication of simian virus 40 (SV40) DNA and the various periods of the host-cell cycle was investigated in synchronized CV(1) cells. Cells synchronized through a double excess thymidine procedure were infected with SV40 at the beginning or the middle of S, or in G(2). The first viral progeny DNA molecules were in all instances detected approximately 20 h after release from the thymidine block, independent of the time of infection. The length of the early, prereplicative phase of the virus growth cycle therefore depended upon the period of the cell cycle at which the cells were infected. Infection with SV40 was also performed on cells obtained in early G(1) through selective detachment of cells in metaphase. As long as the cells were in G(1) at the time of infection, the first viral progeny DNA molecules were detected during the S period immediately following, whereas if infection took place once the cells had entered S, no progeny DNA molecule could be detected until the S period of the next cell cycle. These results suggest that the infected cell has to pass through a critical stage situated in late G(1) or early S before SV40 DNA replication can eventually be initiated.

Animals↗
PubMed1972

Thermosensitive block of the Sabin strain of poliovirus type I.

The thermosensitive defect of the Sabin LSc2ab strain of poliovirus type I was studied. Transfer of infected KB cells from 36 to 38.5 C resulted in 30% inhibition of viral RNA replication but in 90% inhibition of formation of virions. Neither 74S procapsids nor 14S particles were detected in the cells transferred to the non-permissive temperature. However, procapsids, once accumulated at 36 C, were normally stable at 38.5 C and could transform into virions at that temperature. Viral proteins synthesized at the nonpermissive temperature were not different from those synthesized at permissive temperature, as judged from their pattern in polyacrylamide gel electrophoresis and from the fact that they normally matured into virions when the infected cells were brought back to permissive temperature, even under conditions of inhibition of protein synthesis. This leads to the conclusion that the defect in the Sabin strain studied lies in the assembly of its viral capsid proteins into capsomeres.

Carcinoma↗