PubMed Health⌕ Search

Biomedical subjects

C Randell

Publications and source records attributed to C Randell.

6 recordsLinked to original sources
PubMed1993

The influence of growth medium on the yield of X-ray-induced chromatid exchanges in the presence and absence of aphidicolin.

The frequency of exchanges in JU56 cells irradiated in the G2 phase in the presence and absence of the polymerase inhibitor aphidicolin (APC), and in the presence of a range of concentrations of cysteine was measured. It was found that in the absence of cysteine, incubation for 2 h with APC had no effect on the yield. Addition of cysteine at concentrations of 50-250 mg/l reduced the frequency of exchanges, and at these concentrations the frequency was increased by incubation with APC. At higher concentrations, the yield was reduced and incubation with APC did not elevate it. In following experiments, it was found that incubation with cysteine for a period of longer than 10 minutes was necessary before APC affected the yield of exchanges.

Animals↗
PubMed1988

An investigation using inhibition of G2 repair of the molecular basis of lesions which result in chromosomal aberrations.

Cultures of JU56 cells were irradiated with 2.5 Gy X-rays and 16 h later the cultures were exposed to a moderately inhibitory dose of 1-beta-D-arabinofuranosylcytosine (ara-C) or aphidicolin (APC) and to colcemid, for 2 h. The c-metaphases collected for examination had therefore been exposed to X-rays in G1 or early S, and to the repair inhibitors APC and ara-C during the latter half of G2. It was found that treatment of cells irradiated early in cell cycle, that is, in G1 and early S, with APC or ara-C in G2, (1) reduced the frequency of chromatid and chromosome exchanges below that of cells treated with X-rays alone, (2) produced no more chromatid breaks and gaps than were seen in unirradiated cells, (3) increased the number of chromosome fragments and gaps in a more than additive fashion, and (4) produced only an additive effect, by comparison with the effect of X-rays and drug given separately, on the total number of chromosomal aberrations.

Animals↗
PubMed1988

Synergism of 1-beta-D-arabinofuranosylcytosine with itself and aphidicolin.

JU56 cells have been exposed to 1-beta-D-arabinofuranosylcytosine (ara-C) in S phase, and again to aphidicolin (APC) or ara-C during G2, and examined for chromosomal aberrations at c-metaphase. It was found that the two exposures acted synergistically in the production of chromosomal lesions of both the chromatid and isochromatid type. The results were interpreted as indicating that inhibition of the G2 repair system prevented the repair of DNA single-strand regions produced by the incorporation of ara-C during semi-conservative DNA synthesis.

Aphidicolin↗
PubMed1986

Dose relationships between different effects of aphidicolin in JU56 cells.

Some effects of aphidicolin have been investigated in relationship to dose, in a permanent cell line, JU56. Inhibition of semi-conservative DNA synthesis occurred at concentrations greater than 3 X 10(-7) M. In this respect the cells were about as sensitive as L1210 and HeLa cells, and more than 10-fold more sensitive than PHA-stimulated human peripheral blood leucocytes. Delay of progress of cells through G2 occurred at concentrations which inhibited synthesis to about 2% of control levels. Chromatid aberrations appeared in cells at concentrations which decreased synthesis to 5%. Synergism with X-rays in the production of chromatid aberrations occurred at doses which reduced semi-conservative synthesis to 40% of control levels. Isochromatid aberrations appeared in cells continuously exposed to aphidicolin in G2 at concentrations which reduced synthesis to 5% of control units.

Animals↗
PubMedDate not supplied

MR imaging using a rampable system.

A series of cranial images obtained at three magnetic field strengths in a volunteer on a fast ramp magnetic resonance system is presented. This study was undertaken in the space of 5 h.

Brain↗