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In this study, a series of novel Isoquinolinone derivatives were synthesized as potential multi-target antipsychotics. Among these, compound 13 showed high affinity for dopamine D

Listeria monocytogenes is an important foodborne pathogenic bacterium that is explicitly threatening public health and food safety. Rapid, simple, and sensitive detection methods for this pathogen are of urgent need for the increasing on-site testing demands. Application of the isothermal recombinase polymerase amplification (RPA) and the lateral flow strip (LFS) in the detection is promising for fast speed, high sensitivity, and little dependency on equipment and trained personnel. However, the simplicity comes with an intrinsic and non-negligible risk, the false-positive signals from primer–dimers. In this study, an improved RPA–LFS system was established for detection of L. monocytogenes that eliminated false-positive signals from primer–dimers. Primer candidates were carefully selected from the entire L. monocytogenes genome sequence and rigorously screened for specific amplifications in PCR and RPA reactions. For the optimal primer pairs, probes that matched the targeted fragment sequences, although had the smallest chance to form cross-dimers with the primers, were designed and screened. The intelligent use of the probe successfully linked the positive signal to the actual amplification product. This RPA–LFS system was highly specific to L. monocytogenes and was able to detect as low as 1 colony-forming unit of the bacterium per reaction (50 μl) without DNA purification, or 100 fg of the genomic DNA/50 μl. The amplification could be conducted under the temperature between 37 and 42°C, and the whole detection finished within 25 min. Test of artificially contaminated milk gave 100% accuracy of detection without purification of the samples. Various food samples spiked with 10 colony-forming unit of L. monocytogenes per 25 g or 25 ml were successfully detected after an enrichment time period of 6 h. The RPA–LFS system established in this study is a rapid, simple, and specific detection method for L. monocytogenes that has eliminated false-positive results from primer–dimers. In addition, this study has set a good example of eliminating the false-positive risk from primer–dimers in isothermal amplification-based detection methods, which is applicable to the development of detection technologies for other pathogens.

Background: Vibrio alginolyticus is an important pathogen that has to be closely monitored and controlled in the mariculture industry for its strong pathogenicity, quick onset after infection and high mortality rate to aquatic animals. Fast, simple and specific methods are demanded for its on-site detection to effectively control its outbreaks and prevent economic losses. Detection specificity towards the pathogenic strains has to be emphasized to facilitate pointed treatment and prevention. Polymerase chain reaction (PCR) based molecular approaches have been developed, but their application is limited due to the requirement for complicated thermal cycling machines and trained personnel. Results: A fast, simple and highly specific detection method for V. alginolyticus pathogenic strains was established based on the isothermal recombinase polymerase amplification (RPA) and lateral flow dipsticks (LFD). The method targeted a virulence gene toxR that was reported to have a good coverage for the V. alginolyticus pathogenic strains. To ensure the specificity, the primer-probe set of the RPA system was carefully designed to recognize regions in gene toxR that were diverged in different Vibrio species but conserved in V. alginolyticus pathogenic strains. The primer-probe set was determined after a systematic screening on amplification performance, primer-dimer formation and false positive signals.The RPA-LFD method was confirmed to have a high specificity to V. alginolyticus pathogenic strains without any cross reaction with other Vibrio species, and was able to detect as low as 1 colony forming unit per microliter of the bacterium without DNA extraction. The method finishes detection within 30 min under the temperature between 35oC and 45oC, and the visual signal on the dipstick was directly read with naked eye. In an application simulation, randomly infected shrimp homogenate samples were 100% accurately detected. Conclusions: ​The RPA-LFD method developed in this study is fast, simple, highly specific and independent of complicated equipment. It is well applicable to the on-site detection of V. alginolyticus pathogenic strains for the mariculture industry.

Listeria monocytogenes is an important foodborne pathogenic bacterium that is explicitly threatening public health and food safety. Rapid, simple, and sensitive detection methods for this pathogen are of urgent need for the increasing on-site testing demands. Application of the isothermal recombinase polymerase amplification (RPA) and the lateral flow strip (LFS) in the detection is promising for fast speed, high sensitivity, and little dependency on equipment and trained personnel. However, the simplicity comes with an intrinsic and non-negligible risk, the false-positive signals from primer–dimers. In this study, an improved RPA–LFS system was established for detection of L. monocytogenes that eliminated false-positive signals from primer–dimers. Primer candidates were carefully selected from the entire L. monocytogenes genome sequence and rigorously screened for specific amplifications in PCR and RPA reactions. For the optimal primer pairs, probes that matched the targeted fragment sequences, although had the smallest chance to form cross-dimers with the primers, were designed and screened. The intelligent use of the probe successfully linked the positive signal to the actual amplification product. This RPA–LFS system was highly specific to L. monocytogenes and was able to detect as low as 1 colony-forming unit of the bacterium per reaction (50 μl) without DNA purification, or 100 fg of the genomic DNA/50 μl. The amplification could be conducted under the temperature between 37 and 42°C, and the whole detection finished within 25 min. Test of artificially contaminated milk gave 100% accuracy of detection without purification of the samples. Various food samples spiked with 10 colony-forming unit of L. monocytogenes per 25 g or 25 ml were successfully detected after an enrichment time period of 6 h. The RPA–LFS system established in this study is a rapid, simple, and specific detection method for L. monocytogenes that has eliminated false-positive results from primer–dimers. In addition, this study has set a good example of eliminating the false-positive risk from primer–dimers in isothermal amplification-based detection methods, which is applicable to the development of detection technologies for other pathogens.

In this study, a series of novel Isoquinolinone derivatives were synthesized as potential multi-target antipsychotics. Among these, compound 13 showed high affinity for dopamine D2 and serotonin 5-HT1A, 5-HT2A, 5-HT6, and 5-HT7 receptors, showed low affinity for off-target receptors (5-HT2C, H1, and α1), and negligible effects on ether-a-gogo-related gene (hERG; i.e., reduced QT interval prolongation). An animal behavioral study revealed that compound 13 reversed APO-induced hyperlocomotion, MK-801-induced hyperactivity, and DOI-induced head twitch. Moreover, compound 13 exhibited a high threshold for acute toxicity, a lack of tendency to induce catalepsy, and did not cause prolactin secretion or weight gain when compared to risperidone. Furthermore, in the forced swim test, tail suspension test, and novel object recognition test, treatment with compound 13 resulted in improvements in depression and cognitive impairment. In addition, compound 13 had a favorable pharmacokinetic profile in rats. Thus, the antipsychotic drug-like effects of compound 13 indicate that it may be useful for developing a novel class of drugs for the treatment of schizophrenia.