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E Magdon

Publications and source records attributed to E Magdon.

12 recordsLinked to original sources
PubMed1976

[Experimental results with different fractionation regimes and low-LET irradiation of mice (author's transl)].

The effect of several fractionation regimes was examined by the model of mammary tumour in C3H-mice. The best results were observed with several fractionations daily. No curative effect was obtained by means of a total dose of 6000 rd achieved with all fractionation regimes. The results of investigations underline the importance of considering cellular proliferation kinetic processes in malignant tumours in order to optimize the temporal distribution of radiation dose.

Animals↗
PubMed1976

[Studies for a mathematical model of the proliferation kinetics of mammary carcinomas by means of electronic data processing (author's transl)].

Continuing an earlier publication in which the growth of spontaneous mammary carcinomas in female mice of a C3H inbred strain was described, in the present paper the growth rate is expressed by a mathematical function, and is adapted by electronic data processing to the experimental values of 60 tumors classified into seven "growth types". For mathematical description the tumors were conveniently assumed to have a spherical shape, and the main reason for the reduction in volume increase with increasing tumor size was thought to be insufficient supply with oxygen and the essential nutrients S. Including the experimental data of all carcinomas investigated, the minimum concentration of S necessary for mitotic activity of the tumor cells was calculated to be 65% of the normal level. As the average for all the tumors investigated, a time of at least 33 hrs is required for the tumor volume to double.

Animals↗
PubMed1975

[IV. Studies on cell biological experiments to the relative biological effectiveness (RBE) of fast neutrons in different phantom depths (author's transl)].

From carcinomas of the collum uteri and from human embryos (10 weeks) primary cell cultures were obtained, irradiated with 60Co-gamma-rays and fast neutrons (6,2 mev), respectively, in doses ranging from 50 to 300 rad in the phantom depth of 3 and 12 cm at 37 degrees C, and the number of mitotically surviving cells was determined. From the survival curves, the values of D37, Do and Dq were determined. The studies have shown that embryonic cells have higher Dq values than the tumor cells under study, while there were no distinct differences in primary radiation sensitivity Do between normal and tumor cells when considering biological variability. The relative biological effectiveness (RBE) of the 6,2 mev neutrons proved clearly dependent on the level of the single dose or of percent survival rate, respectively. The minima of the RBE values were obtained refering to Do (2,2-2,7). From the quotient RBE (tumor cells)/RBE (embryonic cells) ranging from 0.88 to 1.23 depending on the reference system, the different phantom depth and the cell cultures used can be concluded that the stronger biological effectiveness of fast neutrons is not necessarily an additional therapeutical advantage, but that the "anoxic gain factor" and the ensueing increased killing of hypoxic tumor cells has to be considered as the main advantage of neutron therapy. Using the neutron therapy in a phantom depth of 12 cm, a slow increase of the RBE-values can be registered in comparison to the radiation in a depth of 3 cm, if for the formation of the RBE-values the pure dose of neutrons without reference to the gamma-ray part will be employed. When we use for the formation of the RBE-values the neutron-dose including the dose for the corresponding gamma-ray part, a change of the RBE on the phantom depth tested here is not detectable.

Culture Techniques↗
PubMed1975

[Studies on the growth rate of spontaneous mammary carcinomas in C3H inbred mice (author's transl)].

The incidence of spontaneous mammary carcinomas was determined in the C3H mouse inbred colony reared in Berlin-Buch over the past three years. Only female animals reaching a lifespan of no less than 170 days, corresponding to the longevity of the shortest lived animal in which a mammary carcinoma developed, were included in the study. A 50% incidence of mammary carcinomas was found with female animals above one year of age. The median age for the incidence of tumours was 446 days. Related to tumour-free females which at least have reached the median tumours age, the proportion of females developing mammary carcinomas was 86.8%. With increasing litters the tumour latency decreased from 491 for monoparous females to 383 days for mothers with 7 to 8 litters. The growth rate of 60 tumours under observation was found to vary grossly. With the minimum volume doubling time being the same in all cases, the growth rate of the tumours varied according to longer or shorter phases of stagnation or delay. Tumours having approximately equal growth rates throughout the period of investigation were classified as a "growth type". Altogether, seven growth types for spontaneous mammary carcinomas were established.

Animals↗
PubMed1975

[Possible quantification of vascularization and of non-proliferating, hypoxic and nerotic proportions of lung cancer in man (author's transl)].

In hematoxylin-eosin stained quatorial sections of 14 human bronchial tumors, the relative proportions of different tissue elements were determined in two perpendicular planes, 500 and 200 mu wide, using the target principle. Data characterizing the level of necrotization of these tumors have revealed a poor supply of oxygen and nutritive substances to tumors in which large stroma areas were alternating with large fields of tumor parenchyma. As anticipated, necrotization increases with increasing size of the tumor. A network of narrow stroma strips in the tumor affords a more favourable supply of the cells. The proportions of necrotic, hypoxic and GO areas were calculated.

Blood Vessels↗