ABSTRACT
We introduce a lateral flow assay (LFA) integrated with a modified isothermal nucleic acid amplification procedure for rapid and simple genetic testing. Padlock probes specific for the target DNA were designed for ligation, followed by rolling circle amplification (RCA) using capture ligand-modified oligonucleotides as primers. After hybridization with detection linker probes, the amplified target DNA is flowed through an LFA membrane strip for binding of gold nanoparticles as the substrate for colorimetric detection. We established and validated the "RCA-LFA" method for detection of mecA, the antibiotic resistance gene for methicillin-resistant Staphylococcus aureus (MRSA). The assay was optimized using various concentrations of primers and probes for RCA and LFA, respectively. The sensitivity was determined by performing RCA-LFA using various amounts of mecA target DNA, showing a detection limit of ~ 1.3 fmol. The specificity of the assay was examined using target DNAs for other resistance genes as the controls, which demonstrated positive detection signals only for mecA DNA, when added either individually or in combinations with the control targets. Furthermore, applying the RCA-LFA method using specifically designed probes for RNA-dependent RNA polymerase (RdRp) and receptor binding domain (RBD) gene for SARS-CoV-2, which demonstrated feasibility of the method for viral gene targets. The current method suggests a useful platform which can be universally applied for various nucleic acid targets, allowing rapid and sensitive diagnosis at point-of-care. Supplementary Information: The online version contains supplementary material available at 10.1007/s13206-022-00080-1.
ABSTRACT
This study aims to identify age-related suicide-related factors and changes in suicide rate before and after the onset of the COVID-19 pandemic. METHODS: From 2018 to 2020, the patients who presented to the ED of a university hospital with a suicide attempt were classified into adolescents (≤18 years), adults (19-65 years), and elderly (>65 years), and the visits were grouped into before and after COVID-19. RESULTS: There were 853 visits before and 388 visits after COVID-19, and the results showed that the number of adolescent and adult suicide patients increased immediately after the pandemic, but the overall trend did not show a significant difference from before the pandemic. In the adolescents, the ratio of male patients increased, interpersonal and school-related motivations decreased, the poisoning and cutting methods of suicide were more common, and hospitalization admissions increased. Among the elderly, the ratio of female patients increased, the number of single patients and patients without previous psychiatric problems increased, the motives for physical illness and death of people around increased, the falling and hanging methods of suicide were more common, and hospitalization admissions and deaths increased. CONCLUSION: The impact of COVID-19 on suicide rates and suicide-related factors varies by age group. This finding requires different approaches and methods to suicide prevention based on age.