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Biomedical subjects

H Shimojo

Publications and source records attributed to H Shimojo.

At least 73 records · Page 4Linked to original sources
PubMed1977

Helper factor(s) for growth of adeno-associated virus in cells transformed by adenovirus 12.

Evidence is presented that a helper factor(s) for growth of adeno-associated virus (AAV) is present in cells transformed by adenovirus type 12 (Ad12). The growth of AAV was observed in heterokaryons formed by fusion of human KB and Ad12-transformed rodent cells by using ultraviolet-inactivated Sendai virus without coinfection of cells with adenovirus. The presence of the helper factor(s) for AAV growth in rat cells transformed by the EcoRI-C fragment or the HindIII-G fragment of Ad12DNA suggests that the helper factor(s) induced by infection with adenovirus is the Ad12-specific T antigen.

Adenoviridae↗
PubMed1977

Isolation and preliminary characterization of temperature-sensitive mutants of the murine sarcoma leukaemia virus complex.

Five temperature-sensitive mutants (ts I to 5) were isolated from a stock of the Moloney strain of murine sarcoma leukaemia virus complex which had been mutagenized by ultraviolet irradiation or N-methyl-N'-nitro-N-nitrosoguanidine. In mouse cells at the non-permissive temperature the mutants formed fewer foci of transformed cells than at the permissive temperature. The ts mutants were characterized by testing: (I) murine leukaemia virus (MuLV) clones from the ts complex, (2) the effect of additional wild type MuLV on focus formation, (3) focus formation in rat cells and (4) focus formation with pseudotypes rescued from non-producer cells. Two mutants (ts 1 and ts 3) were found to be ts MuLVs which did not possess heat labile virion proteins and were not ts in post-penetration helper functions necessary for the fixation of sarcoma virus transformation. The remaining three mutants (ts 2, ts 4 and ts 5) were ts murine sarcoma viruses which, however, showed no temperature-sensitive effect on the maintenance of transformed cell morphology nor on colony forming efficiency in soft agar.

Animals↗
PubMed1977

Isolation of the viral DNA replication complex from adeno-associated virus type 1-infected cells.

The replication complex active in adeno-associated virus type 1 (AAV-1) DNA synthesis in vitro was solubilized, with a nonionic detergent, from the nuclei of human embryonic kidney cells coinfected with AAV-1 and an early temperative-sensitive mutant (ts125) of human adenovirus type 5 at the nonpermissive temperature (40.5 degrees C). The complex sedimented with a mean size of 23S and contained parental AAV-1 DNA. Most of the DNA synthesized with the AAV-1 DNA replication complex in vitro was AAV-1 DNA, as revealed by DNA-DNA hybridization and sedimentation in a neutral sucrose gradient. However, it sedimented in an alkaline sucrose gradient as molecules smaller than AAV-1 DNA (14.4S). The AAV-1 DNA replication complex was not formed in cells infected with AAV-1 alone.

Adenoviridae↗
PubMed1976

Viral DNA synthesis in vitro with the inclusions isolated from adenovirus 12-infected cells.

A fraction defined as the inclusions was isolated by banding in CsC1 gradients from nuclei of adenovirus 12-infected KB cells. When examined by electron microscopy, the isolated inclusions were relatively homogeneous, finely granular materials of moderate electron density, possibly representing the disintegrated type II or IV inclusions. The conditions of endogenous DNA synthesis in vitro with the inclusions were determined. The product of DNA synthesis in vitro with the inclusions was mainly viral and scarcely cellular, as revealed by DNA-DNA hybridization and methylated albumin kieselgur column chromatography. However, viral DNA synthesized in vitro was smaller (18S, 22S) than viral DNA in virions (31 S, 34 S) in neutral and alkaline sucrose gradients. Effects of various treatment of the inclusions on the DNA-synthesizing activity showed that phospholipase C inhibited the activity efficiently. The in vitro DNA synthesis was stimulated by addition of the cytoplasmic extract from adenovirus 12-infected cells and not that from unifected cells. The analysis of the composition of the inclusions showed that the inclusions contained DNA, protein, phospholipid and a small amount of RNA and carbohydrate.

Adenoviruses, Human↗
PubMed1975

Effect of protease inhibitors on focus formation by murine sarcoma virus.

The effect of six protease inhibitors, isolated from various species of actinomycetes, on focus formation by murine sarcoma virus was examined. Pepstatin was the only inhibitor. The treatment of cells with pepstatin at various times possibly retards the early stage of infection with murine sarcoma virus.

Animals↗
PubMed1975

The viral DNA replication machinery of adenovirus 12.

The viral DNA replication complex was found in the M band after fractionation. However, it did not associate with the nuclear membrane, but was found in association with types II and IV inclusions. It is suggested, therefore, that the viral DNA replication complex is the inclusions types II and IV. The analysis with Ad12 ts mutants showed the involvement of three viral genes in initiation of viral DNA replication, in formation of the viral DNA replication complex and the inclusions types II and IV. Temperature sensitivity of the gene products involved in viral DNA replication was also examined. From the data presented, the following sequence of viral DNA replication in Ad12-infected cells is suggested: (1) Synthesis of a protein (gene A product), which may be an acceptor or may modify the nuclear constituent to be an acceptor for parental viral DNA, to form the viral DNA replication complex; (2) synthesis of a protein (gene B product), which may be required for the parental viral DNA to associate with the acceptor and to form a type II inclusion-like structure (precursor of type II inclusion?); (3) synthesis of a protein (gene C product), which may be required for activation of the complex or type II inclusion and to alter type II inclusion to type IV inclusion. Further studies are necessary to substantiate the suggestion.

Adenoviridae↗
PubMed1975

Virus infections in laboratories in Japan.

Virus infections in laboratories in Japan from 1967 to 1972 were studied. Major causative agents were influenza virus, Australian antigen, Rickettsia, and vaccinia virus. The cases reported were neither severe, nor lethal. It was suggested that these infections were caused either by aerosol or contact. Measures to prevent infection in laboratories are discussed.

Hepatitis B Antigens↗