[en] Dietary additives (cow's milk, rat diet or some rat diet ingredients) were administered to 6-day-old artificially fed suckling rats. ¹⁴¹Ce was administered orally. Rat diet ingredients (fish meal, sunflower meal, alfalfa, cane molasses and premix) were found to be extremely efficient in reducing cerium retention even if administered two days after ¹⁴¹Ce application. (author) 4 refs.; 1 tab

[en] Short communication

[en] We investigated the influence of oral and parenteral administration of chelation therapy on the retention of ¹⁴¹Ce in young rats. Opposite to results obtained in adult rats present results show high efficacy of oral chelation therapy in reducing radiocerium retention in the whole body and organs of suckling rats. (author) 3 refs

No abstract available

[en] To study the effects of LH on total testicular blood flow and microcirculation, rats were treated with 2,5 or 25 μg LH sc and measurements were made on control rats and on LH-treated rats 1,2,3,4,6 and 12 h, after treatment. After treatment with 25 μg LH, total testicular blood flow, as measured with the radioactive microsphere method, was decreased at 6 h and increased at 12 h. Testicular microcirculatory blood flow was recorded with laser Doppler flowmetry and regular oscillations in blood flow, vasomotion, was observed in control rats. Vasomotion was not present 4 and 6 after treatment with 25 μg LH, but returned at 12 h. Prior to and concomitantly with these changes in vasomotion, polymorphonuclear leukocytes accumulated in testicular microvessels and migrated into the interstitial tissue. These changes were followed, 6 h after treatment, by an increased vascular permeability, measured as increased testicular interstitial fluid volume. The lower dose of LH (2.5 μg), doubled plasma testosterone concentration and initially decreased interstitial fluid volume, and later induced a slight increase in blood vessel leukocytes. At the times studied, no changes could be observed in the other vascular parameters. In conclusion, it is suggested that LH, probably via some Leydig cell product, promotes regulatory effects on testicular microcirculation, but different magnitudes of LH stimulation induce different responses. (author)

[en] An accurate method for the in vivo determination of stable iodine concentration of tissues during kinetic studies of radiographic substances containing iodine is required. The currently used non-destructive methods, based on the detection of X-ray fluorescent photons, suffer from the limitation due to interfering effect of the attenuation of radiation in the tissue layers overlying the site to be measured. In the present work, the photon scattering method suggested by Pumumalainen et al., is successfully applied for for the qualitative assesment of soft tissue iodine content. The method involves the measurement of the intensity ratio of Rayleigh to Compton scattered photons in a narrow beam geometry. In the present work, measurements are made to study the variation of iodine concentration in water which simulates the kinetics of thyroid iodine, using Rayleigh and Compton scattered photons of incident energy 145 keV. The scattered gamma rays are detected by a high resolution HPGe semiconductor detector. The experiment is performed for different concentrations of KI in the range from 2gm to 10gm in step of 2gm in 10 ml of distilled water. The intensity ratio of coherent to Compton scattered peaks, corrected for photo-peak efficiency of the gamma detector and absorption of photons in the target and air is determined for various concentrations of KI solution

[en] A standard of ¹⁴¹Ce was measured with dose calibrators by the U.S. National Bureau of Standards (NBS) and several Canadian hospitals. The results varied by approximately 30% and indicate a need for improved calibration of these instruments in Canadian hospitals. Details of the NBS method of calibration are given as a commendable example. The suitability of ¹⁴¹Ce as a simulated standard for 6-hour ⁹⁹Tcsup(m) is discussed. It is suggested that the following are needed: a Canadian commercial supplier of standards of radionuclides, improved measurement capabilities in nuclear medicine clinics and more detailed information and guidance from suppliers of dose calibrators. Appendices to this report describe the standardization of ¹⁴¹Ce by the 4πβ-γ coincidence method and calibration of the Chalk River Nuclear Laboratories 4πγ ionization chamber for ¹⁴¹Ce. (author)

[en] Published in summary form only

[en] The suitability of ¹⁴¹Ce as a particulate digesta flow tracer is studied in sheep. The amount and the factors of cerium uptake on feed particles by incubating alfalfa hay and sorghum seeds in water containing ¹⁴¹Ce in solution are determined. After soaking one hour, 80% radioactivity is retained on the hay 17% on the sorghum. Incubation time is the main factor determining uptake rate. This uptake is solid on the hay and more fragile on the sorghum. The evolution of ¹⁴¹Ce distribution among the different physical constituents of rumen digesta is studied on two sheep given a single radioactive meal (10μCi). These sheep are fitted with a rumen cannula and fed twice daily with hay (80%) and sorghum (20%). There is little ¹⁴¹Ce in solution in the supernatant liquid after centrifugation of digesta. At the end of the 'labelled' meal, specific radioactivity (RAS) of liquid-phase digesta, separated by filtering on two layers of gauze, is equal to or higher than the RAS of the solid phase. It increases up to the next unlabelled meal and then decreases. Microorganisms may cause this transfer of liquid-phase radioactivity to the large particles. Specific radioactivity of the microorganisms remains very high after the 'labelled' meal as compared to that of different granulometric fractions of solid digesta

[en] Characterization of a nuclear fuel for its uniformity, linear density, concentration of fissile material, total length, local hot spots etc. is usually carried out using passive and active gamma ray assay techniques. ⁵⁷Co due to its favourable radiation characteristics (T_1/2:271.8 days, E_γ: 122 keV (85.5%)) is radionuclide of choice in active gamma assay techniques as an external radiometry source in such applications. The energy of gamma rays emitted, its abundance and the half life are the criterion for the selection of the source used. However, ⁵⁷Co is to be imported and due to its very high cost and difficulty in procurement, availability of a suitable indigenously produced radiometry source for such applications was a long felt need from the users in the department. ¹⁴¹Ce with an half life of 32.7 d and having comparable gamma emission E_r145 keV (100% ) was considered as a possible substitute for imported ⁵⁷Co source. The feasibility of its production by neutron irradiation and the fabrication of a sealed source for radiometric applications was therefore studied