3D-printed simulator for nasopharyngeal swab collection for COVID-19.

OBJECTIVES: Diagnosis of COVID-19 is essential to prevent the spread of SARS-CoV-2. Nasopharyngeal swabs (NPS) remain the gold standard in screening, although associated with false negative results (up to 30%). We developed a 3D simulator of the nasal and pharyngeal cavities for the learning and improvement of NPS collection. PATIENTS AND METHODS: Simulator training sessions were carried out in 11 centers in France. A questionnaire assessing the simulator was administered at the end of the sessions. The study population included both healthcare workers (HCW) and volunteers from the general population. RESULTS: Out of 589 participants, overall satisfaction was scored 9.0 [8.9-9.1] on a scale of 0 to 10 with excellent results in the 16 evaluation items of each category (HCWs and general population, NPS novices and experienced). The simulator was considered very realistic (95%), easy to use (97%), useful to understand the anatomy (89%) and NPS sampling technique (93%). This educational tool was considered essential (93%). Participants felt their future NPS would be more reliable (72%), less painful (70%), easier to perform (88%) and that they would be carried out more serenely (90%). The mean number of NPS conducted on the simulator to feel at ease was two; technical fluency with the simulator can thus be acquired quickly. CONCLUSION: Our simulator, whose 3D printing can be reproduced freely using a permanent open access link, is an essential educational tool to standardize the learning and improvement of NPS collection. It should enhance virus detection and thus contribute to better pandemic control.

Purification, characterization and cloning of isovaleryl-CoA dehydrogenase from higher plant mitochondria.

Between the different types of Acyl-CoA dehydrogenases (ACADs), those specific for branched chain acyl-CoA derivatives are involved in the catabolism of amino acids. In mammals, isovaleryl-CoA dehydrogenase (IVD), an enzyme of the leucine catabolic pathway, is a mitochondrial protein, as other acyl-CoA dehydrogenases involved in fatty acid beta-oxidation. In plants, fatty acid beta-oxidation takes place mainly in peroxisomes, and the cellular location of the enzymes involved in the catabolism of branched-chain amino acids had not been definitely assigned. Here, we describe that highly purified potato mitochondria have important IVD activity. The enzyme was partially purified and cDNAs from two different genes were obtained. The partially purified enzyme has enzymatic constant values with respect to isovaleryl-CoA comparable to those of the mammalian enzyme. It is not active towards straight-chain acyl-CoA substrates tested, but significant activity was also found with isobutyryl-CoA, implying an additional role of the enzyme in the catabolism of valine. The present study confirms recent reports that in plants IVD activity resides in mitochondria and opens the way to a more detailed study of amino-acid catabolism in plant development.

Characterization of a plant mitochondrial active chromosome.

A method is presented for the partial purification of a plant mitochondrial active chromosome (MAC). This method is based on the presence of the mitochondrial chromosome in the insoluble mitochondrial fraction which allows for its rapid purification from the bulk of detergent-solubilized proteins by ultra-centrifugation. The resuspended MAC carrying DNA and RNA-binding proteins retains DNA synthesis and transcription activities comparable to the ones found in isolated mitochondria. In comparison, tRNA-nucleotidyl terminal transferase taken as an example of RNA modifying activities remains in the soluble fraction. MAC purification is proposed as a rapid and efficient first step in the purification of DNA-binding proteins involved in DNA replication and transcription.