Production of 89Sr in solution reactor.

The new method for medical (89)Sr production in a reactor with solution fuel is proposed which is characterized by simplicity, high production efficiency and low buildup of radioactive waste. The main advantages of the new technology were validated by numerous experiments. The proposed new technology selectively extracts (89)Sr from a fuel of solution reactor and precludes penetration of (90)Sr into the final product. This method is based on the presence of gaseous radionuclide (89)Kr (T(1/2)=190.7s) in the decay chain (89)Se-->(89)Br-->(89)Kr-->(89)Rb-->(89)Sr. The performed experiments on taking the gas probes from internal volume of the solution 20 kW mini-reactor "Argus" have confirmed that the mechanism for (89)Sr delivery to the sorption volume of the reactor experimental loop is based on transport of gaseous (89)Sr predecessor-radionuclide (89)Kr. According to the measurements of radioactive impurities in a final (89)SrCl(2) solution, the filtration of the gas flow with cermet filters followed by cleaning of (89)Sr chloride solution in chromatographic columns with DOWEX-50 x 8 or Sr-Resin ensures reception of (89)Sr fully meeting the requirements for medical application. The experimental estimations have shown that the proposed new technology is multiply more productive than the traditional industrial methods of (89)Sr reception.

Beneficial and harmful effects of L-arginine on renal ischaemia.

BACKGROUND: The role of nitric oxide (NO) in acute renal failure (ARF) is not yet completely understood. L-Arginine (L-arg) is protective against different ARF models, while L-arg addition in isolated proximal tubules enhances hypoxia/reoxygenation (H/R) injury. The aim of this study was to evaluate the effects of L-arg on renal ischaemia. METHODS: In in vivo studies, Wistar rats were subjected to 60 min renal artery clamping, and renal function was evaluated 2 and 15 days after ischaemia. Four groups were studied: (1) control; (2) acute L-arg (50 mg/kg/bw i.v.); (3) L-nitro-arginine-methyl esther (L-NAME; 0.5 mg/kg/bw i.v.); and (4) chronic L-arg (L-arg 0.25% in drinking water/7 days). For the in vitro studies, proximal tubules (PTs), isolated by collagenase digestion and Percoll gradient, were studied from three groups: (1) untreated; (2) L-arg-treated (L-arg 0.25% in drinking water/7 days); and (3) L-NAME-treated rats (3 mg/kg in drinking water/7 days). PTs were kept oxygenated or subjected to 15 min hypoxia (H-15) and 35 min reoxygenation (R-35). In some experiments, additional doses of L-arg and L-NAME were administered. Cell injury was assessed by lactate dehydrogenase (LDH) release. NO production was evaluated by NO2-/NO3- measurement (Griess reaction) in both urine and isolation medium. RESULTS: After 2 days, L-arg infusion protected against ischaemia compared with control rats (0.4 vs 0.2 ml/min/100 g, P < 0.001), while neither L-NAME nor chronic L-arg supplementation ameliorated renal function. After 15 days, both acute and chronic L-arg groups showed a higher glomerular filtration rate (0.6 and 0.75 ml/min/100 g) compared with control rats (0.3 ml/min/100 g, P < 0.05) and L-NAME-treated rats (0.2 ml/min/100 g, P < 0.05). Despite similar recovery in both L-arg groups, the mortality rate was 25% in the chronic L-arg group. Tubular function was also better preserved in the acute L-arg group. PTs isolated from L-arg-treated rats were more sensitive to isolation injury. L-Arg addition enhanced H/R injury (44.9 vs 51.8%, P < 0.05), whereas L-NAME addition protected (44.9 vs 24%, P < 0.001) in untreated rats. In L-arg-treated rats, addition of L-arg did not enhance H/R injury (49.6 vs 53.5%, NS) and L-NAME was still protective (49.6 vs 32.3%, P < 0.001). In PTs from L-NAME-treated rats, L-arg addition also did not enhance H/R injury (50 vs 54%, NS) whereas L-NAME was protective (50 vs 27%, P < 0.001). NO2-/NO3- production paralleled L-arg and L-NAME supplementation. CONCLUSION: It was demonstrated that acute L-arg infusion was beneficial in in vivo renal ischaemia while it was harmful in isolated H/R tubules. In contrast, chronic L-arg supplementation was deleterious both in in vivo and in vitro renal ischaemia, suggesting that injurious effects had overcome the beneficial effects during excess NO exposure.