G G Jonsson

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Hyperthermia has been shown in vitro and in vivo to potentiate the effects of ionizing irradiation. Previous studies found that hyperthermia alters the metabolism of adenosine diphosphate (ADP)-ribose polymers required for recovery from DNA damage and that poly(ADP-ribose) polymerase activity is very sensitive to cellular nicotinamide-adenine dinucleotide(More)
The effects of supranormal temperature on the activity of poly(ADP-ribose) glycohydrolase were studied by assaying the enzyme in cell extracts derived from cells subjected to hyperthermia and comparing with extracts that were heated in vitro. The enzyme activity was reduced by both hyperthermic treatment of cells and by heating of cell extracts; however(More)
Inhibitors of the chromatin-associated enzyme adenosine diphosphate ribosyltransferase have been found to inhibit DNA strand rejoining and to potentiate lethality of DNA-damaging agents both in vivo and in vitro. We have in this work examined the radiosensitizing potential of one such inhibitor, nicotinamide, on tumor tissue by using transplanted C3H mouse(More)
Inhibitors of the chromosomal enzyme ADP-ribosyl transferase, like nicotinamide, have been shown to inhibit DNA strand rejoining and also to potentiate the lethality of DNA damaging agents in vitro. We have examined the radiosensitizing potential of nicotinamide in vivo by using transplanted C3H mouse mammary adenocarcinomas as our model system. Our data(More)
The effects of hyperthermia on adenine nucleotide metabolism including NAD and poly(ADP-ribose) have been studied in confluent cultures of C3H10T1/2 cells. Cells replated immediately following hyperthermic treatment showed only 9% survival relative to controls while after a 24-h recovery period at 37 degrees C survival was 87% of control. Hyperthermic(More)
DNA repair has been investigated, estimated by unscheduled DNA synthesis (UDS) and the cellular NAD+ pool, after exposing human mononuclear leukocytes to hyperthermia and gamma radiation separately and in combination. It was found that gamma radiation induced a decline in UDS with increasing temperature through the temperature region studied (37-45 degrees(More)
Effects of hyperthermia and nicotinamide on ADP-ribosyl transferase activity (ADPRT), unscheduled DNA synthesis (UDS), NAD+- and ATP-pools and cytotoxicity were investigated in gamma-irradiated human mononuclear leukocytes. A significant decrease in radiation-induced UDS after heat treatment for 45 min was found. Nicotinamide increased the UDS levels in(More)
Effects of hyperthermia (42.5 degrees C) and gamma radiation (30 Gy) on ADP-ribosyl transferase, NAD+, and ATP pools in human mononuclear leukocytes have been investigated. It was found that the gamma-ray activation level of the enzyme was not influenced by this hyperthermia for 45 min. Following deprivation of ATP synthesis by 2,4-dinitrophenol, an(More)
We have directly compared in resting human mononuclear leukocytes the DNA repair effects caused by ADP-ribosyl transferase (ADPRT) activity following DNA damage induction by gamma radiation, UV radiation, ethylene oxide (EO) and N-acetoxy-2-acetylaminofluorene (NA-AAF). The presence of inhibitors of ADPRT during the quantitation of unscheduled DNA synthesis(More)