Download Do = 228 (155-432) [tg/ml

756
PROCEEDINGS OF THE EUROPEAN SOCIETY FOR RADIATION BIOLOGY
radiation and with a number of chemo- CHEMICALS IN VITRO. M. KUCEROVA,
therapeutic agents. The hypoxic fraction of Genetic Laboratory, Institute of Hygiene and
the B16 melanoma was not modified by prior Epidemiology, Prague.
treatment with cyclophosphamide but it wras
Human peripheral blood samples from 2
increased when BCNU was given. Treatment healthy donors wvere exposed in vitro to
with 1000 rad of y-irradiation rendered the 200 R of x-rays and/or to 10-4 mol solution of
tumour cells more resistant to drugs.
TEPA or 10-6 mol solution of Epichlorhydrin
HILL, R. P. & STANLEY, J. A. (1975) The Response in different phases of cell cycle. Using the
of Hypoxic B16 AMelanoma Cells to in vivo trypsin banding method, detailed cytogenetic
Treatment with Chemotherapeutic Agents. Can- analysis revealed difterent types of chromocer Res., 35, 1147.
somal aberrations induced by radiation and by
chemicals, even if the cells were exposed to
mutagens in the same phase of cell cycle.
INTERACTION OF ACTINOMYCIN Non-random distribution of breaks of indiD, RADIATION AND YEAST CELL vidual chromosomes as well as especially
SURVIVAL. E. VAN DUYSE, A. DUNJIC fragile or resistant bands were found, but
and P. LIPNIK, Laboratoire de Radiobiologie, differently after irradiation and after exInstitut du Cancer, Universite Catholique de posure to chemicals tested. Most probably
Louvain, Leuven.
the differences could be explained by a
The survival of yeast cells after irradiation different mutagenic mechanism of these 2
and the use of actinomycin D in the culture types of mutagens.
mediumwerefurther investigated (Van Duyse
and Dunjic, European Society for Radiation COMBINED EFFECTS OF BLEOBiology, Tenth Annual Meeting, Madrid MYCIN AND X-RAYS ON DNA
1973).
SYNTHESIS IN ASCITES TUMOUR
Additional data concern dose-response CELLS. I. V. CHAPMAN and F. A. ALALAWI,
relationship of both radiation and drug Department of Medical Biophysics, The
effects. Based on 66 individual observations, University, Dundee.
the parameters of cell survival curve for
The separate effects of each agent on
actinomycin D are:
DNA synthesis have been investigated using
1-07 (0-83-1-38),
14C-thymidine tracer techniques and Ehrlich
ascites tumour cells in predomitetraploid
228
(155-432)
[tg/ml
Do =
nantly stationary phase suspensions. The
The potentiation of radiation effects writh studies reveal that whilst the effect on
actinomycin D was studied following con- intracellular pool size is markedly different
centration in culture medium from 12-5 ,ug/ml for each agent, inhibition of the rate of
to 125 jug/ml. The significant differences are incorporation of the tracer into DNA is
obtained only with concentrations of actino- observed in both cases.
mycin D (above 75 jug/ml) which already
A number of schedules involving drug
alone impair the cell proliferation.
treatment and irradiation of the same susFollowing on, three-dimensional data pensions were studied to investigate the
analyses indicate that the enhanced effects of combined effects of bleomycin and x-rays on
radiation and AMD treatment are additive in DNA synthesis. Single doses of bleomycin
nature.
(20 jug/ml) given before or after or simultaAnalyses of cell survival data were per- neously with exposure to x-rays (2.5 krad)
formed by using gamma function model have an additive or less than additive effect.
(Lipnik and Dunjic, 6th L. H. Gray con- However, split bleomycin schedules in comference, London 1974).
bination with x-rays have a significantly
greater than additive effect on DNA synthesis
rates.
COMPARISON OF THE RESULTS
BLEOMYCIN
OF
OF DETAILED ANALYSIS OF CHRO- INTERACTION
IN WITH UNIRRADIATED AND IRRAABERRATIONS
MOSOMAL
AFTER DIATED DNA. J. DIRS, W. K6HNLEIN,
LYMPHOCYTES
HUMAN
EXPOSURE TO RADIATION AND R. SEIDLER, I. TOBtREN-BOTS and W.