[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] A ration of 600 g chopped hay and 150 g ground sorghum is given twice daily to sheep fitted with a rumen cannula and a duodenal reentrant cannula. ¹⁴¹Ce flow rate at the duodenum and in the feces is compared to flow rate of stained hay particles after ingestion of a single labelled meal. After an adaptation period during which both daily meals are labelled, variations in ¹⁴¹Ce concentration are then measured in the duodenal and fecal dry matter. The tracer is used to estimate dry mater digestibility indirectly. Duodenal data show that the mean retention time of ¹⁴¹Ce in the rumen is about 15% less than that of stained particles. The meal after the radioactive one momentarily depresses ¹⁴¹Ce excretion rate while it accelerates that of the stained particles. Mean retention time in the whole gastro-intestinal tract of a meal of 600 g chopped hay 150 g ground sorghum is 40.4+-3.8 h or 32.4+-3.7 h, depending on whether stained particles or ¹⁴¹Ce is used. All the ¹⁴¹Ce ingested is recovered in the feces. Mean recovery of ¹⁴¹Ce in the feces excreted during 200 hours after dosage is 100.2+-5.0%. After a period of adaptation where all meals are radioactive, feces of 2 sheep are sampled either by total collection or directly in the rectum. Dry matter digestibility does not differ whether calculated from total collection or by the indirect method using ¹⁴¹Ce