Optimization of a new scintillation gas detector used to localize electrons emitted by 99mTc.

UNLABELLED: We have developed a scintillation gas detector to localize electrons emitted by 99mTc. This type of detector allows direct quantification of images and so provides a clear advantage over autoradiographic film. We have optimized the device to give an image spatial resolution that closely approximates that of typical autoradiographic film. To improve this resolution, it was necessary to select only low-energy electrons (2 and 15 keV) and to devise novel detection and localization techniques for the ionizing particles. METHODS: A parallel-plate proportional avalanche chamber is subject to a uniform electrical field and amplifies the number of released electrons through collisions of ionizing particles in the gas mixture. Light emitted by the gas scintillator during the avalanche process is collected by a highly intensified charge coupled device camera. The centroid of each resulting light distribution is calculated, resulting in a quantitative mapping of the sample's activity. Insertion of the sample within the gas volume improves the efficiency and so provides a method that is both very sensitive and linear. RESULTS: We have shown that in a parallel-plate structure, the application of a high electrical field to the surface of the sample and the selection of appropriate light spots, according to their morphology, can overcome localization errors due to the particles' trajectories. We have obtained a resolution of the order of 30 microm, using electrons from 99mTc. CONCLUSION: This detection technique allows considerable improvement in image resolution. This "electron camera" is a serious rival to existing autoradiographic techniques, because it provides certain other advantages, including direct quantification, linearity, high dynamic range and low noise levels. Thus, new perspectives are made available in quantitative double tracer autoradiography, because electrons can be selected for imaging as a function of their energy.

Isolation of 10 differentially expressed cDNAs in p53-induced apoptosis: activation of the vertebrate homologue of the drosophila seven in absentia gene.

We report the isolation of 10 differentially expressed cDNAs in the process of apoptosis induced by the p53 tamor suppressor. As a global analytical method, we performed a differential display of mRNA between mouse M1 myeloid leukemia cells and derived clone LTR6 cells, which contain a stably transfected temperature-sensitive mutant of p53. At 32 degrees C wild-type p53 function is activated in LTR6 cells, resulting in programmed cell death. Eight genes are activated (TSAP; tumor suppressor activated pathway), and two are inhibited (TSIP, tumor suppressor inhibited pathway) in their expression. None of the 10 sequences has hitherto been recognized as part of the p53 signaling pathway. Three TSAPs are homologous to known genes. TSAP1 corresponds to phospholipase C beta 4. TSAP2 has a conserved domain homologous to a multiple endocrine neoplasia I (ZFM1) candidate gene. TSAP3 is the mouse homologue of the Drosophila seven in absentia gene. These data provide novel molecules involved in the pathway of wild-type p53 activation. They establish a functional link between a homologue of a conserved developmental Drosophila gene and signal transduction in tumor suppression leading to programmed cell death.

[Determination of blood level of muscle enzymes in glycogenoses with liver involvement: a diagnostic criterion]. / La détermination du taux sérique des enzymes musculaires au cours des glycogénoses avec atteinte hépatique: un critère d'orientation diagnostique.

Serum muscle enzyme activity assays were routinely performed in 36 patients with glycogen storage diseases (15 types 1a and 1b, 12 type III, and 9 types VI and IX). Creatine phosphokinase serum activity was increased only in type III. Glutamate-pyruvate transaminase, aldolase and lactate dehydrogenase serum activities were increased in all the forms of glycogen storage disease studied. Muscle involvement may at least partly explain the increased serum enzyme activities in type III.

Crigler-Najjar type II disease inheritance: a family study.

The inheritance of Crigler-Najjar type II disease is still contested. Autosomal dominant transmission with incomplete penetrance and autosomal recessive transmission have been proposed. We had the opportunity to study the hepatic activity of bilirubin uridinediphosphate glucuronyltransferase in parents whose first child had been affected by Crigler-Najjar type II disease. The demonstration of reduced activity of glucuronidation in the liver of both parents suggests autosomal recessive inheritance. The second infant of this couple was affected by the same disease and was treated with success by phenobarbital.