Biomedical subjects

A Fajgelj

Publications and source records attributed to A Fajgelj.

14 recordsLinked to original sources

PubMed2006

Matrix materials for proficiency testing: optimization of a procedure for spiking soil with gamma-emitting radionuclides.

The IAEA Reference Materials Group of the Chemistry Unit, Agency's Laboratories Seibersdorf, has developed and optimized a procedure for spiking some environmental matrices with gamma-emitting radionuclides. This paper describes the spiking procedure, homogeneity testing of the spiked material, and assignment of property values and their associated uncertainties for the radionuclides 54Mn, 65Zn, 60Co, 109Cd, 134Cs, 137Cs, 210Pb, and 241Am. This procedure has already been successfully used in an IAEA proficiency test on the determination of 137Cs and 210Pb in spiked soil and has been found to be appropriate for production of soil materials for proficiency testing and internal quality control samples. The main advantage of this procedure is a low uncertainty arising from heterogeneity, which was found to be less than 1.2% for all the analytes studied.

Journal Article↗

PubMed1997

Chromosome aberrations induced in human lymphocytes by U-235 fission neutrons. Part III: Evaluation of the effect of the induced alpha and beta activity on the chromosomal aberration yield.

AIM: Further experiments were performed to explain a difference in chromosomal aberration yield found between samples cultivated immediately after fission neutron irradiation and samples which were cultivated with 96 h delay after irradiation. MATERIAL AND METHOD: Human peripheral blood samples were irradiated in mixed fission neutron/gamma field (1800 s) and biological effect assessed in the mean of analysis of unstable chromosome aberrations with a time delay in culturing cells of 12, 24, 48, and 96 h. Additional measurements were performed on irradiated and blank blood samples with the aim to detect any increase in alpha and beta activity after fission neutron irradiation. No difference was found. Results were compared to theoretically calculated values of the alpha and beta activity released from natural radioactive isotopes. RESULT AND CONCLUSION: As a conclusion it is shown that in our experimental conditions the secondary effects resulting from nuclear transformations of natural or induced radioactive isotopes, recoil reactions and accompanying alpha, beta, and gamma radiation are not the reason for the increase observed in chromosomal aberration yield in blood samples cultured with a time delay of at least 24 hours.

Alpha Particles↗

PubMed1992

Chromosome aberrations induced in human lymphocytes by U-235 fission neutrons. Part II: Evaluation of the effect of the induced Na-24 activity on the chromosomal aberration yield.

Blood samples were spiked with Na-24 to study the separate effect of this nuclide on the incidence of chromosomal aberrations in neutron irradiated blood samples. A delay of 96 h was allowed before cultivation, so the results of chromosomal aberration analysis could be compared with the results obtained by direct irradiation of blood samples with U-235 fission neutrons [7]. The absorbed dose was calculated using a simple conservative model. From the results obtained we can conclude that Na-24 alone was not the reason for the difference in the incidence of chromosomal aberrations between blood samples cultivated immediately after "in vitro" irradiation by U-235 fission neutrons and samples which were cultivated after 96 h storage.

Absorption↗

PubMed1991

Chromosome aberrations induced in human lymphocytes by U-235 fission neutrons: I. Irradiation of human blood samples in the "dry cell" of the TRIGA Mark II nuclear reactor.

A set-up for irradiation of biological samples in the TRIGA Mark II research reactor in Ljubljana is described. Threshold activation detectors were used for characterisation of the neutron flux, and the accompanying gamma dose was measured by TLDs. Human peripheral blood samples were irradiated "in vitro" and biological effects evaluated according to the unstable chromosomal aberrations induced. Biological effects of two types of cultivation of irradiated blood samples, the first immediately after irradiation and the second after 96 h storage, were studied. A significant difference in the incidence of chromosomal aberrations between these two types of samples was obtained, while our dose-response curve fitting coefficients alpha 1 = (7.71 +/- 0.09) x 10(-2) Gy-1 (immediate cultivation) and alpha 2 = (11.03 +/- 0.08) x 10(-2) Gy-1 (96 h delayed cultivation) are in both cases lower than could be found in the literature.

Chromosome Aberrations↗

PubMed1974