A density correction method for radioactive waste drum based on SRGS technology.

The segmented ringed gamma scanning (SRGS) technique represents an advancement in segmented gamma scanning (SGS) technology used for detecting the density of radioactive waste drums, offering enhanced measurement accuracy. However, significant occur errors in the reconstruction of matrix densities due to the non-uniform distribution of density in radioactive waste and the conical beam emitted from the transmission source collimator. This paper proposes a density correction method based on dichotomy to address this issue. The efficacy of this method was verified through both simulations and experiments on a sample containing five different materials, utilizing 137Cs and 60Co for transmission and emission measurements, respectively. The experimental results demonstrate that the errors in the corrected matrix densities are reduced, falling within a margin of 16.8%. Additionally, the corrected reconstruction error of the activity is approximately 25% of the uncorrected results.

Computational Identification of Guillain-Barré Syndrome-Related Genes by an mRNA Gene Expression Profile and a Protein-Protein Interaction Network.

Background: In the present study, we used a computational method to identify Guillain-Barré syndrome (GBS) related genes based on (i) a gene expression profile, and (ii) the shortest path analysis in a protein-protein interaction (PPI) network. Materials and Methods: mRNA Microarray analyses were performed on the peripheral blood mononuclear cells (PBMCs) of four GBS patients and four age- and gender-matched healthy controls. Results: Totally 30 GBS-related genes were screened out, in which 20 were retrieved from PPI analysis of upregulated expressed genes and 23 were from downregulated expressed genes (13 overlap genes). Gene ontology (GO) enrichment and KEGG enrichment analysis were performed, respectively. Results showed that there were some overlap GO terms and KEGG pathway terms in both upregulated and downregulated analysis, including positive regulation of macromolecule metabolic process, intracellular signaling cascade, cell surface receptor linked signal transduction, intracellular non-membrane-bounded organelle, non-membrane-bounded organelle, plasma membrane, ErbB signaling pathway, focal adhesion, neurotrophin signaling pathway and Wnt signaling pathway, which indicated these terms may play a critical role during GBS process. Discussion: These results provided basic information about the genetic and molecular pathogenesis of GBS disease, which may improve the development of effective genetic strategies for GBS treatment in the future.

Effects of L-arabinose efflux on λ Red recombination-mediated gene knockout in multiple-antimicrobial-resistant Salmonella enterica serovar Choleraesuis.

In this study, six swine-derived multiple-antimicrobial-resistant (MAR) strains of Salmonella Choleraesuis (S. Choleraesuis) were demonstrated to possess higher efflux pump activity than the wild-type (WT). L-Arabinose, a common inducer for gene expression, modulated S. Choleraesuis efflux pump activity in a dose-dependent manner. At low L-arabinose concentrations, increasing L-arabinose led to a corresponding increase in fluorophore efflux, while at higher L-arabinose concentrations, increasing L-arabinose decreased fluorophore efflux activity. The WT S. Choleraesuis that lacks TolC (ΔtolC), an efflux protein associated with bacterial antibiotic resistance and virulence, was demonstrated to possess a significantly reduced ability to extrude L-arabinose. Further, due to the rapid export of L-arabinose, an efficient method for recombination-mediated gene knockout, the L-arabinose-inducible bacteriophage λ Red recombinase system, has a reduced recombination frequency (~ 12.5%) in clinically isolated MAR Salmonella strains. An increased recombination frequency (up to 60%) can be achieved using a higher concentration of L-arabinose (fivefold) for genetic manipulation and functional analysis for MAR Salmonella using the λ Red system. The study suggests that L-arabinose serves not only as an inducer of the TolC-dependent efflux system but also acts as a competitive substrate of the efflux system. In addition, understanding the TolC-dependent efflux of L-arabinose should facilitate the optimization of L-arabinose induction in strains with high efflux activity.

Infiltration and persistence of lymphocytes during late-stage cerebral ischemia in middle cerebral artery occlusion and photothrombotic stroke models.

BACKGROUND: Evidence suggests that brain infiltration of lymphocytes contributes to acute neural injury after cerebral ischemia. However, the spatio-temporal dynamics of brain-infiltrating lymphocytes during the late stage after cerebral ischemia remains unclear. METHODS: C57BL/6 (B6) mice were subjected to sham, photothrombosis, or 60-min transient middle cerebral artery occlusion (MCAO) procedures. Infarct volume, neurodeficits, production of reactive oxygen species (ROS) and inflammatory factors, brain-infiltrating lymphocytes, and their activation as well as pro-inflammatory cytokine IFN-γ production were assessed. Brain-infiltrating lymphocytes were also measured in tissue sections from post-mortem patients after ischemic stroke by immunostaining. RESULTS: In mice subjected to transient MCAO or photothrombotic stroke, we found that lymphocyte infiltration persists in the ischemic brain until at least day 14 after surgery, during which brain infarct volume significantly diminished. These brain-infiltrating lymphocytes express activation marker CD69 and produce proinflammatory cytokines such as IFN-γ, accompanied with a sustained increase of reactive oxygen species (ROS) and inflammatory cytokines release in the brain. In addition, brain-infiltrating lymphocytes were observed in post-mortem brain sections from patients during the late stage of ischemic stroke. CONCLUSION: Our results demonstrate that brain-infiltration of lymphocytes persists after the acute stage of cerebral ischemia, facilitating future advanced studies to reveal the precise role of lymphocytes during late stage of stroke.