Une méthode d'amplification génique isotherme

A gene amplification technique applied to the detection of HIV and which can be implemented without programmable thermocyclers is described. The reaction products are high molecular weight strands of DNA that can be detected using simple methods, even without electrophoresis. This is a promising technique for in situ amplification experiments. Our findings show that this amplification method is compatible with the temperature levels encountered in living cells. This technology could thus be the basis for a new class of drugs intended for treatment by gene therapy of certain diseases, including malaria and AIDS.     

Validation du logiciel de semi-quantification DaTQUANT® dans l’aide à l’analyse visuelle en TEMP au 123I-FP-CIT dans l’étude des pathologies neurodégénératives

ObjectiveSemi-quantification is a valuable tool increasing the diagnosis accuracy of the single photon emission computer tomography (SPECT) with FP-CIT-¹²³I (DaTSCAN^®), particularly in cases where visual analysis is unclear and especially on the posterior putamen. The DaTQUANT^® software (GE^® Healthcare), allows a quick and simple uptake assessment on several regions of interest. It also provides deviation values compared to a database of healthy subjects obtained in the ENC-DAT project. However, any threshold value is currently validated routinely.Patients and methodsA retrospective study was conducted in 55 patients (33 men, 22 women) referred for a suspicion of neurological disorders and who underwent SPECT imaging with DaTSCAN^® on camera D670 GE^®. Final diagnosis made by neurologist time after the SPECT was established as a reference, reinforced by clinical evolution. Analysis was initially visual without semi-quantitative results, realized by two experimented nuclear physicians, and then semi-quantitative analysis was made by DaTQUANT^® with calculation of Youden indices and ROC curves so as to define threshold values for six regions of interest (caudate, putamen anterior, posterior putamen, bilaterally).ResultsInterobserver match in the blind visual analysis was excellent with kappa coefficient = 0.91, CI at 95% = [0.87–0.95]. The semi-quantitative and statistical analysis by DaTQUANT^® determined pathological threshold values for each region of interest, setting a standard deviation percentage from a database of healthy subjects, worth −16.3% for the right posterior putamen (sensitivity of 100% and specificity of 88%) and −18.3% for the left posterior putamen (sensitivity of 100% and specificity of 97%).ConclusionThe pathological threshold values defined by our study would improve the data analysis obtained from DaTQUANT^® software and would support the DaTSCAN^® visual analysis. Nevertheless, such statistical values are complementary to visual analysis.     

Du microcosme évolutif à la théorie générale : les escargots,Steve Gould et l’évolution

From an Evolutionary Microcosm to general theory: Land Snails, Steve Gould and Evolution. From 1962 to the end of his career, Stephen Jay Gould has studied the land snails of the genera Poecilozonites and then Cerion. Snails have provided him material to develop his morphometric methods, to analyze shell growth, and may have been at the origin of his work on ontogeny and phylogeny. Their variation, which he interpreted in terms of adaptation until the beginning of the 1980s, has been later reanalyzed by him in terms of non-adaptive evolution and contingency. Growth and variation of the shell allowed Gould to define constraint and canalisation in evolution. In their taxonomic work, Gould and Woodruff have practiced a definition of biological species as the group of populations allowing maximal congruence of their morphological characters, genetic characters and geographic distribution, of which potential interfecundity is necessary, but not sufficient. To cite this article: S. Tillier, C. R. Palevol 2 (2003).