The emergence and quick spread of SARS-CoV-2 has pointed at a low capacity response for testing large populations in many countries, in line of material, technical and staff limitations. The ...traditional RT-qPCR diagnostic test remains the reference method and is by far the most widely used test. These assays are limited to a few probe sets, require large sample PCR reaction volumes, along with an expensive and time-consuming RNA extraction step. Here we describe a quantitative nanofluidic assay that overcomes some of these shortcomings, based on the BiomarkTM instrument from Fluidigm. This system offers the possibility of performing 4608 qPCR end-points in a single run, equivalent to 192 clinical samples combined with 12 pairs of primers/probe sets in duplicate, thus allowing the monitoring of SARS-CoV-2 including the detection of specific SARS-CoV-2 variants, as well as the detection other pathogens and/or host cellular responses (virus receptors, response markers, microRNAs). The 10 nL-range volume of BiomarkTM reactions is compatible with sensitive and reproducible reactions that can be easily and cost-effectively adapted to various RT-qPCR configurations and sets of primers/probe. Finally, we also evaluated the use of inactivating lysis buffers composed of various detergents in the presence or absence of proteinase K to assess the compatibility of these buffers with a direct reverse transcription enzymatic step and we propose several protocols, bypassing the need for RNA purification. We advocate that the combined utilization of an optimized processing buffer and a high-throughput real-time PCR device would contribute to improve the turn-around-time to deliver the test results to patients and increase the SARS-CoV-2 testing capacities.
Aveux et témoignages ont longtemps été suffisants pour convaincre les magistrats et un jury. Actuellement, c’est l’exploitation scientifique des indices qui constitue la base de toutes les ...investigations sur les scènes d’infraction. Afin de s’adapter à ce changement, la gendarmerie nationale a construit une chaîne criminalistique, reposant sur des spécialistes, formés à la détection et au prélèvement de ces indices. Afin d’analyser ces échantillons, l’Institut de Recherche Criminelle de la Gendarmerie Nationale (IRCGN) est créé en 1987.
La délivrance de résultats fiables repose sur la compétence des experts. Pour cela, et compte tenu de la grande variété des techniques et des savoirs à détenir par les experts servant au laboratoire, la politique de recrutement et le suivi du déroulé de carrière sont individualisés. Outre la nécessité de disposer d’un bon niveau scientifique initial, il faut aussi avoir envie de travailler au plus près des scènes de crime, à côté des enquêteurs. La compétence des experts fait donc naturellement, l’objet de contrôles réguliers au travers la norme d’accréditation des laboratoires ISO 17025, de même que les méthodes employées et l’interprétation des résultats fournis. L’essentiel de l’activité de l’IRCGN consiste ainsi à exploiter et donc analyser les nombreux indices qui lui sont transmis, mais aussi à envoyer des équipes d’experts sur le terrain pour en prélever sur les scènes d’investigations, tout en rédigeant des rapports où ces résultats sont interprétés selon l’environnement de leur découverte, afin d’être exploitables au procès pénal.
In the past, confession and testimonies were sufficient to convince magistrates and member of the jury. Nowadays, the scientific evidence has become a basic element for criminal investigations. In regards of this evolution, the gendarmerie has created a “criminalistic chain” based on criminal investigations specialists in charge of collecting samples from crime scenes. A specific unit dedicated to the analysis of these samples has been created in 1987 and named Gendarmerie Forensic Institute (IRCGN: Institut de Recherche Criminelle de la Gendarmerie Nationale).
Competence is a fundamental requirement to produce reliable products. The great diversity of the scientific and technical specialities operated in the Institute requires a highly individualized recruitment amongst the candidates who have not only to account of exclusive skills but also of a great interest in the forensic police field. The competence of officers is tested regularly under ISO 17025 accreditation norm, together with the validity of the method used, particularly in the interpretation of the results. For forensic Institutes the core products comprise – among others- the collection of evidence at the crime/incident scene, analysis of seized material, interpretation of the analytical results or other findings and expert reports where the activities and findings are summarized and evaluated.
The Forensic Science Institute of the French "Gendarmerie Nationale" (IRCGN™) developed in 2015 an ISO 17025 certified mobile DNA laboratory for genetic analyses. This Mobil'DNA laboratory is a fully ...autonomous and adaptable mobile laboratory to perform genetic analyses in the context of crime scenes, terrorism attacks or disasters.To support the hospital taskforce in Paris during the peak of the COVID-19 epidemic, we adapted this mobile genetic laboratory to perform high-throughput molecular screening for coronavirus SARS-CoV-2 by real-time PCR. We describe the adaptation of this Mobil'DNA lab to assist in Coronavirus SARS-CoV-2 diagnosis.
The Forensic Science Institute of the French “Gendarmerie Nationale” (IRCGN™) developed in 2015 an ISO 17025 certified mobile DNA laboratory for genetic analyses. This Mobil’DNA laboratory is a fully ...autonomous and adaptable mobile laboratory to perform genetic analyses in the context of crime scenes, terrorism attacks or disasters. To support the hospital task force in Paris during the peak of the COVID-19 epidemic, we adapted this mobile genetic laboratory to perform high-throughput molecular screening for coronavirus SARS-CoV-2 by real-time PCR. We describe the adaptation of this Mobil’DNA lab to assist in Coronavirus SARS-CoV-2 diagnosis.
The comparison of the chemical composition of bullet alloys yields further information for forensic investigations. When a bullet fragment is found completely crushed, the comparison of ...micro-striations is impossible. The only way to compare two bullets is by comparison of their chemical composition. An ICP-MS method is able to measure the percentage of antimony, amounts of trace elements and lead isotopic ratios of the bullets. While recent studies show the random composition of bullet alloys, the measurement of lead isotopic ratios acts as a signature of bullet origin and gives reliable results. The ICP-MS method is a comprehensive tool for this kind of analysis.
Chimie et expertise René Amalberti, Patrick Arpino, Pierre Carlotti, Pierre Charrue, Guillaume Cognon, Laurence Dujourdy, Frédéric Dupuch, Bruno Feignier, François Fontaine, Bertrand Frère, Armand Lattes, Sandrine Pereira-Rodrigues, Pauline Sibille, Gérard Sousi, Pierre Toulhoat, Patrick Touron, Bruno Vanlerberghe, Phi / Minh-Thu Dinh-Audouin, Danièle Olivier, Paul Rigny
2015
eBook
Évaluation de la Date D'Un Tir Persin, BenoÎT; Touron, Patrick; Mille, Fabien ...
Journal - Canadian Society of Forensic Science,
20/1/1/, Letnik:
40, Številka:
2
Journal Article
Recenzirano
Une méthode permettant de dater un tir est présentée. La technique analytique est décomposée en deux étapes: d'abord un prélèvement par microextraction en phase solide (SPME) à l'intérieur du canon ...d'un fusil de chasse, suivi d'une analyse par chromatographie en phase gazeuse couplée à un détecteur à ionisation de flamme (GC/FID) ou à un spectromètre de masse (GC/MS). Des produits typiques résultant d'une combustion incomplète ont été détectés et dix d'entre eux ont été identifiés comme étant des hydrocarbures polycycliques aromatiques (HPA). L'analyse simultanée de quatre de ces HPA (naphtalène, 1-méthyl naphtalène, 2-méthyl naphtalène et acénaphtylène) confirme que le fusil de chasse suspecté a tiré récemment, quel que soit le couple munition-arme. L'évaluation de la date du tir est basée sur le taux d'échappement de ces HPA hors du canon du fusil. Une mesure quotidienne de l'aire du pic de naphtalène peut permettre une évaluation de la date d'un tir sous certaines conditions. Tout d'abord, l'origine des HPA sera examinée en étudiant différentes munitions. Puis, la technique analytique sera expliquée avant l'étude de différents paramètres, telles les conditions environnementales lors du tir, la longueur des canons et leur obturation, la présence de lubrifiant et enfin, le nombre de tir.
Automated analysis of fire residues involves a strategy which deals with the wide variety of received criminalistic samples. Because of unknown concentration of accelerant in a sample and the wide ...range of flammable products, full attention from the analyst is required. Primary detection with a photoionisator resolves the first problem, determining the right method to use: the less responsive classical head-space determination or absorption on active charcoal tube, a better fitted method more adapted to low concentrations can thus be chosen. The latter method is suitable for automatic thermal desorption (ATD400), to avoid any risk of cross contamination. A PONA column (50 m×0.2 mm i.d.) allows the separation of volatile hydrocarbons from C
1 to C
15 and the update of a database. A specific second column is used for heavy hydrocarbons. Heavy products (C
13 to C
40) were extracted from residues using a very small amount of pentane, concentrated to 1 ml at 50°C and then placed on an automatic carousel. Comparison of flammables with referenced chromatograms provided expected identification, possibly using mass spectrometry. This analytical strategy belongs to the IRCGN quality program, resulting in analysis of 1500 samples per year by two technicians.
PDF
