(234)U/(238)U activity ratio disequilibrium technique for studying uranium mobility in the Opalinus Clay at Mont Terri, Switzerland

Mobility of naturally occurring U-238 and U-234 radionuclides was studied in a low permeability, reducing claystone formation (Opalinus Clay) near its contact with an overlying oxidising aquifer (Dogger Limestones) at Mont Terri, Switzerland. Our data point to a limited redistribution of U in some of the studied samples. Observed centimetre-scale U mobility is explained by slow diffusive transport of U-234 in the pore waters of the Opalinus Clay driven by spatially variable in situ supply (by alpha-recoil) of U-234 from the rock matrix. Metre-scale mobility is interpreted as a result of infiltration of meteoric water into the overlying aquifer which developed gradients of U concentration across the two rock formations. This triggered a slow in-diffusion of U with (U-234/U-238) > 1 into the Opalinus Clay as attested by a clear-cut pattern of decreasing bulk rock (U-234/U-238) inwards the Opalinus Clay, away from the Dogger Limestones.

Uranium mining industry views on ICRP statement on radon

In 2009, the International Commission on Radiological Protection issued a statement on radon which stated that the dose conversion factor for radon progeny would likely double, and the calculation of risk from radon should move to a dosimetric approach, rather than the longstanding epidemiological approach. Through the World Nuclear Association, whose members represent over 90% of the world's uranium production, industry has been examining this issue with a goal of offering expertise and knowledge to assist with the practical implementation of these evolutionary changes to evaluating the risk from radon progeny. Industry supports the continuing use of the most current epidemiological data as a basis for risk calculation, but believes that further examination of these results is needed to better understand the level of conservatism in the potential epidemiological-based risk models. With regard to adoption of the dosimetric approach, industry believes that further work is needed before this is a practical option. In particular, this work should include a clear demonstration of the validation of the dosimetric model which includes how smoking is handled, the establishment of a practical measurement protocol, and the collection of relevant data for modern workplaces. Industry is actively working to address the latter two items.

Fuel metabolism during exercise in euglycaemia and hyperglycaemia in patients with type 1 diabetes mellitus--a prospective single-blinded randomised crossover trial

We assessed systemic and local muscle fuel metabolism during aerobic exercise in patients with type 1 diabetes at euglycaemia and hyperglycaemia with identical insulin levels.

Body composition and fuel metabolism after kidney grafting

Kidney transplant patients display decreased muscle mass and increased fat mass. Whether this altered body composition is due to glucocorticoid induced altered fuel metabolism is unclear. To answer this question, 16 kidney transplant patients were examined immediately after kidney transplantation (12 +/- 4 days, mean +/- SEM) and then during months 2, 5, 11 and 16, respectively, by whole body dual energy X-ray absorptiometry (Hologic QDR 1000W) and indirect calorimetry. Results were compared with those of 16 age, sex and body mass index matched healthy volunteers examined only once. All patients received dietary counselling with a step 1 diet of the American Heart Association and were advised to restrict their caloric intake to the resting energy expenditure plus 30%. Immediately after transplantation, lean mass of the trunk was higher by 7 +/- 1% (P < 0.05) and that of the limbs was lower by more than 10% (P < 0.01) in patients than in controls. In contrast, no difference in fat mass and resting energy expenditure could be detected between patients and controls. During the 16 months of observation, total fat mass increased in male (+4.9 +/- 1.5 kg), but not in female patients (0.1 +/- 0.8 kg). The change in fat mass observed in men was due to an increase in all subregions of the body analysed (trunk, arms+legs as well as head+neck), whereas in women only an increase in head+neck by 9 +/- 2% (P = 0.05) was detected. Body fat distribution remained unchanged in both sexes over the 16 months of observation. Lean mass of the trunk mainly decreased between days 11 and 42 (P < 0.01) and remained stable thereafter. After day 42, lean mass of arms and legs (mostly striated muscle) and head+neck progressively increased over the 14 months of observation by 1.6 +/- 0.6 kg (P < 0.05) and 0.4 +/- 0.1 kg (P < 0.01), respectively. Resting energy expenditure was similar in controls and patients at 42 days (30.0 +/- 0.7 vs. 31.0 +/- 0.9 kcal kg-1 lean mass) and did not change during the following 15 months of observation. However, composition of fuel used to sustain resting energy expenditure in the fasting state was altered in patients when compared with normal subjects, i.e. glucose oxidation was higher by more than 45% in patients (P < 0.01) during the second month after grafting, but gradually declined (P < 0.01) over the following 15 months to values similar to those observed in controls. Protein oxidation was elevated in renal transplant patients on prednisone at first measurement, a difference which tended to decline over the study period. In contrast to glucose and protein oxidation, fat oxidation was lower in patients 42 days after grafting (P < 0.01), but increased by more than 100% reaching values similar to those observed in controls after 16 months of study. Mean daily dose of prednisone per kg body weight correlated with the three components of fuel oxidation (r > 0.93, P < 0.01), i.e. protein, glucose and fat oxidation. These results indicate that in prednisone treated renal transplant patients fuel metabolism is regulated in a dose-dependent manner. Moreover, dietary measures, such as caloric and fat intake restriction as well as increase of protein intake, can prevent muscle wasting as well as part of the usually observed fat accumulation. Furthermore, the concept of preferential upper body fat accumulation as consequence of prednisone therapy in renal transplant patients has to be revised.