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Biomedical subjects

A Hellman

Publications and source records attributed to A Hellman.

At least 73 records · Page 4Linked to original sources
PubMed1974

Baboon virus isolate M-7 with properties similar to feline virus RD-114.

A virus (M-7) isolated from baboon placental tissue demonstrates many similarities to endogenous feline virus RD-114. Immunodiffusion analysis shows a group-specific antigen (gs-1) line of identity between M-7 and RD-114. Anti-RD-114 DNA polymerase IgG inhibits M-7 polymerase by 57% compared to 97% for RD-114. M-7 virus has helper activity as demonstrated by rescue of murine sarcoma virus (MSV) from sarcoma-positive leukemia-negative human amnion cells. The host range of the rescued M-7 pseudotype of MSV, MSV (M-7), is similar to that of RD-114 virus. MSV (M-7) is also able to transform baboon cells and causes no detectable transformation of feline cells without addition of helper feline leukemia virus. Interference properties of M-7 and RD-114 virus are identical. Virus-specific neutralizing antisera, although partially cross-reacting, can distinguish MSV (M-7) from MSV (RD-114). These similarities and differences between RD-114 and M-7 viruses are best explained as type-specific differences between two viruses within the same strain.

Amnion↗
PubMed1972

Activation of C-type RNA virus markers in mouse uterine tissue.

Synthetic estrogenic compounds, both steroidal and nonsteroidal, and radiation activate markers of C-type virus information in mouse uterine tissue. Both the group-specific viral antigen and the RNA-directed DNA polymerase can be detected within 4 days after stimulation. These observations strengthen the concept of host-modified control mechanisms for expression of C-type virus markers.

Animals↗
PubMed1969

Isoaccepting transfer RNA's of L-M cells in culture and after tumor induction in C3H mice.

Co-chromatography in a reversed-phase column was performed for 16 aminoacyl-tRNA's prepared from L-M cells grown in serum-free suspension culture and from tumors induced in irradiated C(3)H mice by subcutaneous injection of L-M cells. The results showed that between the two sources there were (1) marked differences in aspartyl-, histidyl-, phenylalanyl-, and tyrosyl-tRNA's; (2) significant quantitative differences in isoaccepting species of alanyl-, isoleucyl-, seryl-, and threonyl-tRNA's; and (3) similar to minimally different patterns of arginyl-, methionyl-, prolyl-, tryptophanyl-, valyl-, glycyl-, leucyl-, and lysyl-tRNA's. The differences were evident when synthetases prepared either from L-M cells or from the tumors were used. When the L-M tumors were brought back into in vitro culture, their tRNA patterns were like those of L-M cells. Addition of serum to the culture medium caused the L-M cells to show very minute, but detectable, amounts of the isoaccepting tRNA's found in the tumors. The cellular mechanisms which may be related to the changes of tRNA patterns in the L-M cells are discussed.

Alanine↗
PubMed1969

Glutaraldehyde inactivation of virus in tissue.

High concentrations of influenza virus and T3 coliphage were inoculated into mouse tissue blocks. Exposure of the inoculated tissue blocks to 5% alkaline glutaraldehyde resulted in rapid inactivation of both viral agents.

Aldehydes↗