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Biomedical subjects

C Colby

Publications and source records attributed to C Colby.

At least 37 records · Page 2Linked to original sources
PubMed1975

The effect of serum on the transport and phosphorylation of 2-deoxyglucose by untransformed and transformed mouse 3T3 cells.

Serum starvation of growing and nongrowing (density-inhibited) mouse 3T3 cells resulted in decreased phosphorylation of 2-deoxy--D-glucose, while the time course of transport of this sugar remained unchanged. Serum starvation of SV40 transformed 3T3 cells (SV101) and spontaneously transformed 3T6 cells did not alter either the time course of transport, or phosphorylation of the sugar. Treatment of SV101 cells with 10(-4) M dibutyryl adenosine cyclic 3':5' monophosphate and 10(-3) M theophylline did not restore the capacity to regulate 2-deoxy-D-glucose phosphorylation when these cells were serum deprived. We conclude that serum factors are involved in the modulation of phosphorylation of 2-deoxy-D-glucose in 3T3 cells rather than its transport. This regulation is operative both in growing as well as nongrowing 3T3 cells. In contrast, transformed cells do not respond to this regulation of 2-deoxy-D-glucose phosphorylation.

Biological Transport, Active↗
PubMed1974

Establishment and maintenance of the interferon-induced antiviral state: studies in enucleated cells.

Requirements for the physical presence of the cell's nucleus for the establishment and maintenance of the interferon-induced antiviral state were investigated. Enucleated chicken embryo fibroblasts were obtained by cytochalasin B treatment during centrifugation. The inhibition of vaccinia virus cytoplasmic DNA synthesis, monitored by autoradiography, was used to measure the antiviral activity resulting from interferon treatment. The antiviral state is not established in cells treated with interferon after removal of their nuclei. On the other hand, cells first treated with interferon for 6 or 12 h and then enucleated express the antiviral state. Furthermore, the antiviral state is maintained in enucleated cells for 16 h after enucleation. The antiviral state appears to be more stable in enucleates than in the residual nucleated cells found in the same cultures. Single cells of antiviral populations are found to be either fully permissive or fully restrictive to vaccinia DNA synthesis. The effect of an increasing intracellular multiplicity of infectious virus is to overcome the antiviral cell's block against viral DNA synthesis.

Animals↗
PubMed1973

SV40 virus transformation of mouse 3T3 cells does not specifically enhance sugar transport.

The apparent enhancement of 2-deoxy-D-glucose uptake by mouse 3T3 cells accompanying transformation by SV40 virus is not due primarily to an effect on the transport process but to enhanced phosphorylation of the sugar by intracellular kinases. Moreover, the effect is not specifically a function of the presence of the viral genome, but is a reflection of the overall growth rate and physiological state of the cell.

Animals↗
PubMed1972

Inhibition of early vaccinia virus ribonucleic acid synthesis in interferon-treated chicken embryo fibroblasts.

Pretreatment of chicken embryo cells with homologous but not heterologous interferon inhibits the synthesis of vaccinia virus early messenger ribonucleic acid (mRNA). This inhibition is seen in the presence of cycloheximide, i.e., in the absence of protein synthesis, suggesting that the virion-bound transcriptase may be the target of the antiviral activity associated with interferon treatment. The inhibition of viral mRNA synthesis is dependent on the amount of chicken interferon used. The nonviral interferon inducer, polyriboinosine.polyribocytidine, similarly inhibits viral early mRNA synthesis in a dose-specific manner. The helical polynucleotide polydeoxyinosine.polyribocytidine, which is not an effective interferon inducer in chicken embryo cells, has no effect on viral ribonucleic acid synthesis.

Animals↗
PubMed1971

Mechanism of synthesis of vaccinia virus double-stranded ribonucleic acid in vivo and in vitro.

The synthesis of vaccinia virus double-stranded ribonucleic acid (RNA) in infected HeLa cells was sensitive to actinomycin D, suggesting that a deoxyribonucleic acid dependent reaction is involved. Some double-stranded RNA was made in the presence of cytosine arabinoside in infected cells. Double-stranded and complementary RNA were synthesized in vitro by using vaccinia cores. These two observations indicate that some of the double-stranded RNA is read from "early" genes. The double-stranded RNA synthesized in vitro had the same properties as that made in vivo. At least 70% of the double-stranded RNA made in vivo was in ribonuclease-resistant form prior to sodium dodecyl sulfate-phenol extraction. In addition, there was a complementary RNA in infected cells which could be converted to double-stranded RNA by annealing.

Centrifugation, Density Gradient↗
PubMed1969

The specificity of interferon induction in chick embryo cells by helical RNA.

Treatment of chick embryo cells growing in culture with rI:rC and many other RNA-like polymers results in the induction of interferon. DEAE dextran is required to facilitate the uptake of the RNA into the cells. Interferon-inducing activity is found with a variety of double-stranded helical polynucleotides, provided that all the sugar residues are ribose. However, the effectiveness of different active polynucleotides at a given concentration varies considerably. The differences in activity among the various polynucleotides do not appear to reflect differences in the rate or amount of uptake into the cells or in the rate of intracellular breakdown. Thehigh degree of specificity of the induction process is consistent with the existence of a specific intracellular receptor site, which may be a protein.

Animals↗
PubMed1969

On the biosynthesis and structure of double-stranded RNA in vaccinia virus-infected cells.

The virus-specific, RNase-resistant RNA appearing in vaccinia virus-infected cells was directly shown to be an RNA duplex. After its melting and subsequent banding on Cs(2)SO(4) or incubation with DNase, the RNA could be reannealed and then hybridized with vaccinia virus DNA.The double-stranded virus-specific RNA appears to exist in the cell in the form of heterogeneous partially double-stranded RNA's sedimenting between 9 and 22S. The kinetics of the appearance of the double-stranded RNA in the cell show a dependence on the multiplicity of infection and suggest that the double-stranded RNA is a "late" product of viral intracellular biosynthesis. The synthesis of the double-stranded RNA is inhibited by actinomycin D.

Animals↗