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Biomedical subjects

J A Robb

Publications and source records attributed to J A Robb.

67 records · Page 4Linked to original sources
PubMed1973

Simian virus 40-host cell interactions. I. Temperature-sensitive regulation of SV40 T antigen in 3T3 mouse cells transformed by the ts*101 temperature-sensitive early mutant of SV40.

BALB/3T3 and Swiss/3T3 mouse cells transformed at permissive temperature (33 C) by the early temperature-sensitive mutant of simian virus 40 (SV40), ts(*)101, exhibited a temperature-dependent modulation of SV40 tumor (T) antigen as assayed by immunofluorescence. The percentage of T antigen-positive nuclei in ts(*)101 transformed cells was reduced at restrictive temperature (39 C) when compared to 33 C and to wild-type SV40 transformed cells at either 33 C or 39 C. The percentage of T antigen-positive nuclei in ts(*)101 transformed cells returned to the 33 C control level when the cells were shifted from 39 to 33 C. The ts(*)101 transformed cells could be superinfected with wild-type, but not ts(*)101, virions at 39 C as assayed by an increase in T antigen-positive nuclei.

Adsorption↗
PubMed1972

Proposal for a uniform nomenclature for simian virus 40 mutants.

A uniform nomenclature for simian virus 40 mutants has been developed. This nomenclature should evolve into a comprehensive nomenclature as new mutants and information are obtained. Hopefully, his nomenclature will also stimulate the development of a comprehensive nomenclature for all animal virus mutants.

Genetic Complementation Test↗
PubMed1972

Genetic analysis of simian virus 40. 3. Characterization of a temperature-sensitive mutant blocked at an early stage of productive infection in monkey cells.

A temperature-sensitive mutant of simian virus 40 (SV40), ts(*)101, has been characterized during productive infection in monkey kidney cells. The mutant virion can adsorb to and penetrate the cell normally at the restrictive temperature, but cannot induce the synthesis of cellular deoxyribonucleic acid (DNA) nor initiate the synthesis of SV40-specific tumor, virion, or U antigens or viral DNA. First-cycle infection with purified ts(*)101 DNA is normal at the restrictive temperature, but the resulting progeny virions are still temperature-sensitive. The mutant neither complements nor inhibits other temperature-sensitive SV40 mutants or wild-type virions. The affected protein in the ts(*)101 mutant may be a regulatory structural protein, possibly a core protein, that is interacting with the viral DNA.

Adsorption↗
PubMed1972

Genetic analysis of simian virus 40. IV. Inhibited transformation of Balb-3T3 cells by a temperature-sensitive early mutant.

The temperature-sensitive early mutant, ts(*)101, was characterized during productive infection in monkey cells, and the results are presented in an accompanying paper. This paper demonstrates that although 101 mutant virions adsorb normally to confluent Balb/3T3 mouse cells at both permissive (33 C) and restrictive (38.5 C) temperatures, T antigen synthesis and transformation, abortive and stable, are inhibited at both temperatures (host-range inhibition). T antigen synthesis is temperature sensitive, whereas abortive and stable transformation are not. Clones of 101-transformed Balb/3T3 cells were isolated, and virus was rescued from all clones at both permissive and restrictive temperatures. The rescued virus was as temperature sensitive as the original transforming 101 virions.

Adsorption↗
PubMed1970

Microcloning and replica plating of mammalian cells.

A technique for cloning single mammalian cells has been developed by means of a microculture method (0.010 milliliters per culture). A technique of replica plating has also been developed for use with clones of single cells in microcultures; this technique permits the screening of desired properties of many clones simultaneously before the growth of stock cultures. With these techniques an investigator can with limited budget, space, and personnel perform research using tissue culture systems.

Animals↗
PubMed1969

Maintenance of imaginal discs of Drosophila melanogaster in chemically defined media.

A phosphate-buffered saline and a chemically defined synthetic medium for in vitro maintenance of imaginal discs of Drosophila melanogaster were developed. The composition of the chemically defined medium was varied in order to optimize the incorporation of tritiated uridine into RNA and tritiated amino acids into acid-insoluble protein. The optimal ranges obtained were: pH, 6.75-7.35; osmolarity, 285-345 milliosmoles/liter; sodium concentration, 40-60 mM/liter; potassium concentration, 40-60 mM/liter; magnesium concentration, 0.5-3.5 mM/liter; calcium concentration, 0.3-1.5 mM/liter; and inorganic phosphate concentration, 1.5-4.0 mM/liter. The phosphate-buffered saline is superior to a commonly used insect Ringer solution in maintaining total RNA and acid-insoluble protein synthesis in culture. The chemically defined synthetic medium permits linear total RNA and acid-insoluble protein synthesis for more than 48 hr, DNA synthesis for several hours, normal differentiation to occur after 74 hr in vitro, and trypsinization of imaginal discs into single cell suspensions without developmental damage.

Amino Acids↗
PubMedDate not supplied

Apoptosis in human breast and gastrointestinal carcinomas. Detection in histological sections with monoclonal antibody to single-stranded DNA.

We report application of a novel immunohistochemical procedure for the staining of apoptotic (AP) cells in paraffin sections using monoclonal antibody (MAb) to single-stranded DNA. MAb differentiated between apoptosis and necrosis and in contrast to in situ end labelling specifically stained only AP cells. AP carcinoma cells stained with the antibody were detected in 32 of 58 infiltrating human breast carcinomas and in 9 of 15 colon adenocarcinomas. Stromal cells stained with the MAb were observed in all carcinomas, including those in which no AP carcinoma cells were detected. There was a strong positive correlation between the presence of AP cells, loss of hormone receptors and a high proliferation rate in breast carcinomas. AP cells were present in 80-87% of receptor-negative carcinomas, while most of receptor-positive breast carcinomas did not contain AP cells. Apoptosis in tumor cells was detected significantly more frequently among breast carcinomas with high, than among carcinomas with low S-phase fraction. AP cells were present in 93-95% of breast carcinomas which were receptor-negative and had a high S-phase fraction. Immunostaining demonstrated a strong positive correlation between the loss of bcl-2 protein and intensive apoptosis in breast carcinomas. Association between apoptosis and markers of poor prognosis in breast cancer (loss of hormone receptors, intensive proliferation, loss of bcl-2 protein) indicates that apoptotic cell death is typical of more aggressive carcinomas.

Adenocarcinoma↗