Applicability of a colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for SARS-CoV-2 detection in high exposure risk setting.

OBJECTIVES: During the third wave, the growing number of COVID-19 case clusters reported countrywide in Thailand demonstrated the rapidly evolving characteristics of SARS-CoV-2, the causative agent of the COVID-19 pandemic. The rapid spread of COVID-19 infections had been extensively reported in public areas and construction camps, as well as in congested communities with poor sanitation. High demand for SARS-CoV-2 genome testing and quick reporting by an hour for case identification and isolation characterizes the COVID-19 crisis in Thailand. This situation leads to an urgent need for alternative molecular tests which are reliable, rapid, and cost-effective. METHODS: In this study, we assessed colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP), using real-time reverse transcription-polymerase chain reaction (RT-PCR) as a reference standard, for active case finding in suspected (mostly asymptomatic) cases living in high-risk areas of Bangkok. RESULTS: The diagnostic performance of the RT-LAMP compared with real-time RT-PCR in specimens from 549 Thais were computed in a real-world field study setting. Our study demonstrated that RT-LAMP achieved robust identification of SARS-CoV-2 infection, with a diagnostic sensitivity and specificity of 91.67% and 100%, respectively. CONCLUSION: RT-LAMP is a reliable assay for SARS-CoV-2 detection and is scalable for use in the emergency response to a nationwide pandemic, despite resource limitations. The RT-LAMP real-world data derived from this field study validate its potential use in laboratory practice. RT-LAMP is a good choice as a laboratory-based SARS-CoV-2 molecular test when real-time RT-PCR is not available.

P-cresol and Indoxyl Sulfate Impair Osteogenic Differentiation by Triggering Mesenchymal Stem Cell Senescence.

Chronic kidney disease (CKD) patients obtained high levels of uremic toxins progressively develop several complications including bone fractures. Protein-bound uremic toxins especially p-cresol and indoxyl sulfate are hardly eliminated due to their high molecular weight. Thus, the abnormality of bone in CKD patient could be potentially resulted from the accumulation of uremic toxins. To determine whether protein-bound uremic toxins have an impact on osteogenesis, mesenchymal stem cells were treated with either p-cresol or indoxyl sulfate under in vitro osteogenic differentiation. The effects of uremic toxins on MSC-osteoblastic differentiation were investigated by evaluation of bone phenotype. The results demonstrated that p-cresol and indoxyl sulfate down-regulated the transcriptional level of collagen type I, deceased alkaline phosphatase activity, and impaired mineralization of MSC-osteoblastic cells. Furthermore, p-cresol and indoxyl sulfate gradually increased senescence-associated beta-galactosidase positive cells while upregulated the expression of p21 which participate in senescent process. Our findings clearly revealed that the presence of uremic toxins dose-dependently influenced a gradual deterioration of osteogenesis. The effects partially mediate through the activation of senescence-associated gene lead to the impairment of osteogenesis. Therefore, the management of cellular senescence triggered by uremic toxins could be considered as an alternative therapeutic approach to prevent bone abnormality in CKD patients.