Uranium colloid analysis by single particle inductively coupled plasma-mass spectrometry.

Uranium single particle analysis has been performed by inductively coupled plasma-mass spectrometry (ICP-MS) and the performances are compared with that provided by scanning electron microscopy and single particle counting. The transient signal induced by the flash of ions due to the ionisation of an uranium colloidal particle in the plasma torch can be detected and measured for selected uranium ion masses ((238)U(+), (235)U(+) or (254)[(238)U(16)O](+)) by the mass spectrometer. The signals recorded via time scanning are analysed as a function of particle size or fraction of the studied element or isotope in the colloid phase. The frequency of the flashes is directly proportional to the concentration of particles in the colloidal suspension. The feasibility tests were performed on uranium dioxide particles. The study also describes the experimental conditions and the choice of mass to detect uranium colloids in a single particle analysis mode.

Thorium colloid analysis by single particle inductively coupled plasma-mass spectrometry.

Thorium colloid analysis in water has been carried out by a single particle mode using inductively coupled plasma mass spectrometry (ICP-MS). The flash of ions due to the ionisation of a thorium colloidal particle in the plasma torch can be detected and measured in a time scan for (232)Th (+ ) or (248)[ThO] (+ ) according to the sensitivity required by the mass spectrometer. The peaks of the recorded intensity of the MS signal can be analysed as a function of the particle size or fraction of the studied element in the colloid phase. The frequency of the flashes is directly proportional to the concentration of particles in the colloidal suspension. After discussing Th colloid detection, on the basis of the intensity of the ion flashes generated in the plasma torch, tests were performed on thorium dioxide colloidal particles. This feasibility study also describes the experimental conditions and the limitation of the plasma design to detect thorium colloids in a single particle analysis mode down to about 10fg.

Decarboxylation and carboxylation of pyruvate in the living mice.

Mice received intravenously [1- or 2-14C]acetate, [1-, 2- or 3-14C] or [2-14C]pyruvate and were killed 1, 3, 5 or 15 min later. The radioactivity of CO2 or HCO3- of liver or carcass as well as the radioactivity of blood glucose were measured. The ratio of the radioactivity found in these compounds after [3-14C] or [2-14C-A1pyruvate injection suggests that in the fed aminals: 1. the decarboxylation of the pyruvate was more rapid than its carboxylation, 2. most of the neosynthesized glucose was derived from pyruvate molecules which had undergone a decarboxylation followed by a condensation to citrate, 3. 1/4 to 1/3 of the pyruvate was carboxylated and 2/3 to 3/4 was decarboxylated in animals receiving a diet poor in fats.

Production of CO2 in the living mouse immediately after injection of 1- or 2-14C acetate.

Three groups of mice, normally fed, fasted and fed after a fasting period are injected intravenously with either 1- or 2-14C acetate. The respiratory 14CO2 as well as that of the liver, the adipose tissue and the carcass are collected after 3 min and the radioactivity measured. A determination is also made of the radioactivity of the tissue fatty acids and, for two groups of mice, of the circulating glucose. A calculation is suggested by which the number of revolutions performed by the acetate C in the Krebs cycle before it is transformed into CO2 can be deduced. The results suggest that the Krebs cycle is very open, that the acetate C found in the glucose has already broken away from the cycle after one revolution and that the C which appears in the form of CO2 has performed an average of only 2.8 to 3.6 revolutions. The results are evaluated as a function of the experimental conditions chosen.

[Rapid production of a biotin deficiency in mice]. / Production rapide d'une carence en biotine chez la souris

This work describes a rapid method for the production of a biotin-deficiency in mice. Besides classical morphological symptoms, a decrease of activities of some biotin-dependent enzymes was also observed. The biotin-enzymes are not inhibited at the same extent in a same organ and the metabolic changes do not always follow the enzymatic modifications.

La localisation microsomale de la synthese des acides gras dans le foie de la souris vivante.

Mice were given glucose-U-(14)C and the radioactivity of triglyceride and phospholipid glycerol and fatty acids was measured 30 sec, 3 or 30 min after the i.v. administration in liver microsomes and supernatant. After the acetate administration the radioactivity of palmitic and stearic acids and that of their carboxyl carbons was also measured. The repartition of the radioactivity was discussed in relation with the localization of fatty acid synthesis. In agreement with our previous results it was suggested that the endoplasmic reticulum is the main site of this synthesis.