Point mutations in DNA are useful biomarkers that can provide critical classification of disease for accurate diagnosis and to inform clinical decisions. Conventional approaches to detect point mutations are usually based on technologies such as real-time polymerase chain reaction (PCR) or DNA sequencing, which are typically slow and require expensive lab-based equipment. While rapid isothermal strategies such as recombinase polymerase amplification (RPA) have been proposed, they tend to suffer from poor specificity in discriminating point mutations. Herein, we describe a novel strategy that enabled exquisite point mutation discrimination with isothermal DNA amplification, using mismatched primers in conjunction with a two-round enrichment process. As a proof of concept, the method was applied to the rapid and specific identification of drug-resistant Mycobacterium tuberculosis using RPA under specific conditions. The assay requires just picogram levels of genomic DNA input, is sensitive and specific enough to detect 10% point mutation loading, and can discriminate between closely related mutant variants within 30 min. The assay was subsequently adapted onto a low-cost 3D-printed isothermal device with real-time analysis capabilities to demonstrate a potential point-of-care application. Finally, the generic applicability of the strategy was shown by detecting three other clinically important cancer-associated point mutations. We believe that our assay shows potential in a broad range of healthcare screening processes for detecting and categorizing disease phenotypes at the point of care, thus reducing unnecessary therapy and cost in these contexts.
Data on the prognostic impact of pretherapy 18F-fluorodeoxyglucose–positron emission tomography (FDG-PET) in follicular lymphoma (FL) is conflicting. The predictive utility of pretherapy total metabolic tumor volume (TMTV) and maximum standardized uptake value (SUVmax) on outcome appears to vary between regimens. Chemoimmunotherapies vary in the extent of T-cell depletion they induce. The role of intratumoral T cells on pretherapy FDG-PET parameters is undefined. We assessed pretherapy FDG-PET parameters and quantified intratumoral T cells by multiple methodologies. Low intratumoral T cells associated with approximately sixfold higher TMTV, and FL nodes from patients with high TMTV showed increased malignant B-cell infiltration and fewer clonally expanded intratumoral CD8+ and CD4+ T-follicular helper cells than those with low TMTV. However, fluorescently labeled glucose uptake was higher in CD4+ and CD8+ T cells than intratumoral B cells. In patients with FDG-PET performed prior to excisional biopsy, SUVmax within the subsequently excised node associated with T cells but not B cells. In summary, TMTV best reflects the malignant B-cell burden in FL, whereas intratumoral T cells influence SUVmax. This may contribute to the contradictory results between the prognostic role of different FDG-PET parameters, particularly between short- and long-term T-cell–depleting chemoimmunotherapeutic regimens. The impact of glucose uptake in intratumoral T cells should be considered when interpreting pretherapy FDG-PET in FL.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.