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Biomedical subjects

E Wold

Publications and source records attributed to E Wold.

16 recordsLinked to original sources
PubMed1983

Combined electron radiation and hyperthermia. Repair of DNA strand breaks in NHIK 3025 cells irradiated and incubated at 37, 42.5, or 45 degrees C.

Induction of DNA strand breaks by a short electron pulse (18.5 Gy) and the subsequent strand-break rejoining were investigated at hyperthermia (42.5 and 45 degrees C) and at 37 degrees C during irradiation and repair. The cells were irradiated immediately after 2.5 min equilibration (i.e., from 37 to 42.5 or 45 degrees C) to investigate the effect of short-duration hyperthermia on radiation damage and subsequent repair. Due to a high radiation dose rate and a rapid lysis technique, the cells could be kept at the actual temperature during irradiation and repair, and the strand-break frequency could be measured only seconds after irradiation. At all temperatures, a constant or possible increase in the initial number of breaks was observed during the first 7 sec after the electron pulse. At 37 degrees C, strand-break rejoining was nearly complete within 1 hr. Hyperthermia at 42.5 degrees C had only minor influence on the net rate of strand-break rejoining. At 45 degrees C, 50% of the breaks remained after 1 hr. Subsequent incubation for 23 hr at 37 degrees C reduced by half the number of breaks remaining at 1 hr in irradiated samples. Unirradiated samples exposed to the same heat treatment showed a significant increase in the number of DNA strand breaks. Thus, heat treatment at 45 degrees C may lead to a combined effect of reduced rejoining capacity and formation of breaks after the electron pulse which in turn may be responsible for increased cell death when both modalities are employed.

Animals↗
PubMed1980

The electron affinity of some radiotherapeutic agents used in cancer therapy.

In order to evaluate whether chemotherapeutic compounds applied in cancer treatment might interact with radiation as anoxic cell sensitizers, the electron-affinic properties of DTIC, AIC, hydroxyurea, busulfan and cyclophosphamide were studied by pulse radiolysis. Reaction rates with hydrated electrons were determined for all these compounds. With the exception of DTIC, they all reacted much more slowly with electrons than do most electron-affinic sensitizers. One-electron reduction potentials were determined for DTIC, AIC and hydroxyurea. The values were all in the region for the onset of sensitization, with hydroxyurea as the most promising (E71 =- 0.0552V). For busulfan and cyclophosphamide no value could be determined, but these compounds are probably less electron-affinic than hydroxyurea. A possible application of chemotherapeutic agents as radiosensitizers is discussed.

Antineoplastic Agents↗
PubMed1979

Cavernous haemangioma of the retina.

Seven cases of retinal cavernous haemangioma are presented. Three cases have been followed for more than 6 years, and three cases between 1 and 2 years. Six cases had no eye symptoms related to the vascular tumour, while in one case vitreous haemorrhage occurred on two occasions. On both these occasions full vision was regained. None of the vascular tumours were treated. Two patients had grand mal seizures. They also had convulsive disease in the family history. In three cases family members of two generations were found to have normal eyes on examination.

Adult↗
PubMed1975

Binding of a nitroxyl to radiation-induced DNA transients in repair and repair deficient of E. coli K-12.

Binding of tritiated 2,2,6,6-tetramethyl-4-piperidone-N-oxyl (3H-TAN) to radiation-induced DNA-transients in E. coli K-12 strains AB 1157 and JO 307 rec A uvr A has been studied under in vivo conditions. After irradiation the cells were washed and resuspended in growth medium and left overnight at 37 degrees C. Within an uncertainty of about 10%, no effect of repair could be detected on the yield of TAN bound to DNA for any of the strains. During the period after resuspension. TAN or fragments of TAN leaked out of the irradiated cell samples. This leakage may be attributed to semi-permanant association between TAN and radiation-induced radicals within the cell. The relevance of different interactions between TAN and transients in DNA is discussed.

Cyclic N-Oxides↗