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Background: Ischemic stroke, the most common stroke type, has threatened human life and health. Currently, intravenous thrombolysis and endovascular thrombectomy are the mainstream treatment methods, but they may cause cerebral ischemia-reperfusion injury (CIRI), which aggravates brain injury. Consequently, it is worthwhile to start with a study of CIRI mechanism to identify better prevention and treatment methods. Applying single-cell RNA sequencing (scRNA-seq) technology to further understand the biological functions of various cell types in CIRI will facilitate the intervention of CIRI. Methods: This study aimed to establish a rat middle cerebral artery occlusion (MCAO) model to simulate cerebral ischemia-reperfusion, perform enzymatic hydrolysis, and suspend cerebral cortex tissue edema. Single-cell transcriptome sequencing was used, combined with cluster analysis, t-distributed stochastic neighbor embedding (t-SNE) visualization, and other bioinformatics methods to distinguish cell subgroups while using gene ontology (GO) function enrichment and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment to reveal the biological function of each cell subgroup. Results: We identified 21 brain clusters with cell type-specific gene expression patterns and cell subpopulations, as well as 42 marker genes representing different cell subpopulations. The number of cells in clusters 0-3 increased significantly in MCAO group compared to that in the sham group, and nine-cell subpopulations exhibited remarkable differences in the number of genes. Subsequently, GO and KEGG analyses were performed on the top 40 differentially expressed genes (DEGs) in the six cell subpopulations with significant differences. These results indicate that biological processes and signaling pathways are involved in different cell subpopulations. Conclusions: ScRNA-seq revealed the diversity of cell differentiation and the unique information of cell subpopulations in the cortex of rats with acute ischemic stroke, providing novel insight into the pathological process and drug discovery in stroke. [ABSTRACT FROM AUTHOR]

In this study, a novel, rapid and ultrasensitive fluorescence strategy using the three-dimensional (3D) dynamic DNA walker (DW)-induced branched hybridization chain reaction (bHCR) has been proposed for the detection of ampicillin (AMP). The sensing system was composed of an Nt·Bbvcl-powered DNA walker blocked by an AMP aptamer, hairpin-shaped DNA track probe (TP) and four kinds of metastable hairpin probes as the substrates of bHCR, which triggered the formation of the split G-quadruplex as the signal molecule. Due to the reasonable design, the specific binding between AMP and its aptamer activated the DW, and the DW moved on the surface of the gold nanoparticles (AuNPs) with the help of Nt·Bbvcl to produce primer probes (PPs), which induced bHCR. The products of the bHCR gathered two split G-quadruplex sequences together to form one complete G-quadruplex. The formed G-quadruplex emitted a strong fluorescence signal in the presence of thioflavin-T (ThT) to achieve the purpose of detecting AMP. The sensitivity of this method was greatly improved by the use of the 3D DNA walker and bHCR. The split G-quadruplex enhanced the signal-to-noise ratio (SNR). Under the optimal experimental conditions, a good correlation was obtained between the fluorescence intensity of the sensing system and the concentration of AMP ranging from 5 pM to 500 nM with a limit of detection (LOD) of 3.68 pM. Simultaneously, the method has been applied to the detection of antibiotics in spiked milk samples with satisfactory results. [ABSTRACT FROM AUTHOR]