Fast Detection of SARS-CoV-2 RNA Directly from Respiratory Samples Using a Loop-Mediated Isothermal Amplification (LAMP) Test.

The availability of simple SARS-CoV-2 detection methods is crucial to contain the COVID-19 pandemic. This study examined whether a commercial LAMP assay can reliably detect SARS-CoV-2 genomes directly in respiratory samples without having to extract nucleic acids (NA) beforehand. Nasopharyngeal swabs (NPS, n = 220) were tested by real-time reverse transcription (RT)-PCR and with the LAMP assay. For RT-PCR, NA were investigated. For LAMP, NA from 26 NPS in viral transport medium (VTM) were tested. The other 194 NPS were analyzed directly without prior NA extraction (140 samples in VTM; 54 dry swab samples stirred in phosphate buffered saline). Ten NPS were tested directly by LAMP using a sous-vide cooking unit. The isothermal assay demonstrated excellent specificity (100%) but moderate sensitivity (68.8%), with a positive predictive value of 1 and a negative predictive value of 0.65 for direct testing of NPS in VTM. The use of dry swabs, even without NA extraction, improved the analytical sensitivity; up to 6% of samples showed signs of inhibition. LAMP could be performed successfully with a sous-vide cooking unit. This technique is very fast, requires little laboratory resources, and can replace rapid antigen tests or verify reactive rapid tests on-site.

Arthritis and Diagnostics in Lyme Disease.

The diagnosis of Lyme disease, caused by Borrelia burgdorferi, is clinical but frequently supported by laboratory tests. Lyme arthritis is now less frequently seen than at the time of its discovery. However, it still occurs, and it is important to recognize this, the differential diagnoses, and how laboratory tests can be useful and their limitations. The most frequently used diagnostic tests are antibody based. However, antibody testing still suffers from many drawbacks and is only an indirect measure of exposure. In contrast, evolving direct diagnostic methods can indicate active infection.

The Direct Testing Effect Is Pervasive in Action Memory: Analyses of Recall Accuracy and Recall Speed.

Successful retrieval from memory is a desirably difficult learning event that reduces the recall decrement of studied materials over longer delays more than restudying does. The present study was the first to test this direct testing effect for performed and read action events (e.g., "light a candle") in terms of both recall accuracy and recall speed. To this end, subjects initially encoded action phrases by either enacting them or reading them aloud (i.e., encoding type). After this initial study phase, they received two practice phases, in which the same number of action phrases were restudied or retrieval-practiced (Exp. 1-3), or not further processed (Exp. 3; i.e., practice type). This learning session was ensued by a final cued-recall test both after a short delay (2 min) and after a long delay (1 week: Exp. 1 and 2; 2 weeks: Exp. 3). To test the generality of the results, subjects retrieval practiced with either noun-cued recall of verbs (Exp. 1 and 3) or verb-cued recall of nouns (Exp. 2) during the intermediate and final tests (i.e., test type). We demonstrated direct benefits of testing on both recall accuracy and recall speed. Repeated retrieval practice, relative to repeated restudy and study-only practice, reduced the recall decrement over the long delay, and enhanced phrases' recall speed already after 2 min, and this independently of type of encoding and recall test. However, a benefit of testing on long-term retention only emerged (Exp. 3), when prolonging the recall delay from 1 to 2 weeks, and using different sets of phrases for the immediate and delayed final tests. Thus, the direct testing benefit appears to be highly generalizable even with more complex, action-oriented stimulus materials, and encoding manipulations. We discuss these results in terms of the distribution-based bifurcation model.