Molecular characterization of the PhoPQ-PmrD-PmrAB mediated pathway regulating polymyxin B resistance in Klebsiella pneumoniae CG43

<p>Abstract</p> <p>Background</p> <p>The cationic peptide antibiotic polymyxin has recently been reevaluated in the treatment of severe infections caused by gram negative bacteria.</p> <p>Methods</p> <p>In this study, the genetic determinants for capsular polysaccharide level and lipopolysaccharide modification involved in polymyxin B resistance of the opportunistic pathogen <it>Klebsiella pneumoniae </it>were characterized. The expressional control of the genes responsible for the resistance was assessed by a LacZ reporter system. The PmrD connector-mediated regulation for the expression of <it>pmr </it>genes involved in polymyxin B resistance was also demonstrated by DNA EMSA, two-hybrid analysis and <it>in vitro </it>phosphor-transfer assay.</p> <p>Results</p> <p>Deletion of the <it>rcsB</it>, which encoded an activator for the production of capsular polysaccharide, had a minor effect on <it>K. pneumoniae </it>resistance to polymyxin B. On the other hand, deletion of <it>ugd </it>or <it>pmrF </it>gene resulted in a drastic reduction of the resistance. The polymyxin B resistance was shown to be regulated by the two-component response regulators PhoP and PmrA at low magnesium and high iron, respectively. Similar to the control identified in <it>Salmonella</it>, expression of <it>pmrD </it>in <it>K. pneumoniae </it>was dependent on PhoP, the activated PmrD would then bind to PmrA to prolong the phosphorylation state of the PmrA, and eventually turn on the expression of <it>pmr </it>for the resistance to polymyxin B.</p> <p>Conclusions</p> <p>The study reports a role of the capsular polysaccharide level and the <it>pmr </it>genes for <it>K. pneumoniae </it>resistance to polymyxin B. The PmrD connector-mediated pathway in governing the regulation of <it>pmr </it>expression was demonstrated. In comparison to the <it>pmr </it>regulation in <it>Salmonella</it>, PhoP in <it>K. pneumoniae </it>plays a major regulatory role in polymyxin B resistance.</p

CasNet: Investigating Channel Robustness for Speech Separation

Recording channel mismatch between training and testing conditions has been shown to be a serious problem for speech separation. This situation greatly reduces the separation performance, and cannot meet the requirement of daily use. In this study, inheriting the use of our previously constructed TAT-2mix corpus, we address the channel mismatch problem by proposing a channel-aware audio separation network (CasNet), a deep learning framework for end-to-end time-domain speech separation. CasNet is implemented on top of TasNet. Channel embedding (characterizing channel information in a mixture of multiple utterances) generated by Channel Encoder is introduced into the separation module by the FiLM technique. Through two training strategies, we explore two roles that channel embedding may play: 1) a real-life noise disturbance, making the model more robust, or 2) a guide, instructing the separation model to retain the desired channel information. Experimental results on TAT-2mix show that CasNet trained with both training strategies outperforms the TasNet baseline, which does not use channel embeddings.Comment: Submitted to ICASSP 202

System-Level Biochip for Impedance Sensing and Programmable Manipulation of Bladder Cancer Cells

This paper develops a dielectrophoretic (DEP) chip with multi-layer electrodes and a micro-cavity array for programmable manipulations of cells and impedance measurement. The DEP chip consists of an ITO top electrode, flow chamber, middle electrode on an SU-8 surface, micro-cavity arrays of SU-8 and distributed electrodes at the bottom of the micro-cavity. Impedance sensing of single cells could be performed as follows: firstly, cells were trapped in a micro-cavity array by negative DEP force provided by top and middle electrodes; then, the impedance measurement for discrimination of different stage of bladder cancer cells was accomplished by the middle and bottom electrodes. After impedance sensing, the individual releasing of trapped cells was achieved by negative DEP force using the top and bottom electrodes in order to collect the identified cells once more. Both cell manipulations and impedance measurement had been integrated within a system controlled by a PC-based LabVIEW program. In the experiments, two different stages of bladder cancer cell lines (grade III: T24 and grade II: TSGH8301) were utilized for the demonstration of programmable manipulation and impedance sensing; as the results show, the lower-grade bladder cancer cells (TSGH8301) possess higher impedance than the higher-grade ones (T24). In general, the multi-step manipulations of cells can be easily programmed by controlling the electrical signal in our design, which provides an excellent platform technology for lab-on-a-chip (LOC) or a micro-total-analysis-system (Micro TAS)

Intraprostatic injection of botulinum toxin type- A relieves bladder outlet obstruction in human and induces prostate apoptosis in dogs

BACKGROUND: With the increasing interest with botulinum toxin – A (BTX-A) application in the lower urinary tract, we investigated the BTX-A effects on the canine prostate and also in men with bladder outlet obstruction (BOO) due to benign prostatic hyperplasia (BPH). METHODS: Transperineal injection into the prostate using transrectal ultrasound (TRUS) was performed throughout the study. Saline with or without 100 U of BTX-A was injected into mongrel dogs prostate. One or 3 months later, the prostate was harvested for morphologic and apoptotic study. In addition, eight BPH patients refractory to α-blockers were treated with ultrasound guided intraprostatic injection of 200 U of BTX-A. RESULTS: In the BTX-A treated dogs, atrophy and diffuse apoptosis was observed with H&E stain and TUNEL stain at 1 and 3 months. Clinically, the mean prostate volume, symptom score, and quality of life index were significantly reduced by 18.8%, 73.1%, and 61.5% respectively. Maximal flow rate significantly increased by 72.0%. CONCLUSION: Intraprostatic BTX-A injection induces prostate apotosis in dogs and relieves BOO in humans. It is therefore a promising alternative treatment for refractory BOO due to BPH

Transcriptome profiling of the fifth-stage larvae of Angiostrongylus cantonensis by next-generation sequencing

Angiostrongylus cantonensis is an important zoonotic nematode. It is the causative agent of eosinophilic meningitis and eosinophilic meningoencephalitis in humans. However, information of this parasite at the genomic level is very limited. In the present study, the transcriptomic profiles of the fifth-stage larvae (L5) of A. cantonensis were investigated by next-generation sequencing (NGS). In the NGS database established from the larvae isolated from the brain of Sprague–Dawley rats, 31,487 unique genes with a mean length of 617 nucleotides were assembled. These genes were found to have a 46.08 % significant similarity to Caenorhabditis elegans by BLASTx. They were then compared with the expressed sequence tags of 18 other nematodes, and significant matches of 36.09–59.12 % were found. Among these genes, 3,338 were found to participate in 124 Kyoto Encyclopedia of Genes and Genomes pathways. These pathways included 1,514 metabolisms, 846 genetic information processing, 358 environmental information processing, 264 cellular processes, and 91 organismal systems. Analysis of 30,816 sequences with the gene ontology database indicated that their annotations included 5,656 biological processes (3,364 cellular processes, 3,061 developmental processes, and 3,191 multicellular organismal processes), 7,218 molecular functions (4,597 binding and 3,084 catalytic activities), and 4,719 cellular components (4,459 cell parts and 4,466 cells). Moreover, stress-related genes (112 heat stress and 33 oxidation stress) and genes for proteases (159) were not uncommon. This study is the first NGS-based study to set up a transcriptomic database of A. cantonensis L5. The results provide new insights into the survival, development, and host–parasite interactions of this blood-feeding nematode. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00436-013-3495-z) contains supplementary material, which is available to authorized users

Clinical features and major histocompatibility complex genes as potential susceptibility factors in pediatric immune thrombocytopenia

Background/PurposeImmune thrombocytopenia (ITP) is a heterogeneous autoimmune disorder with diverse response rates to treatments that include corticosteroids, intravenous immunoglobulins (IVIG), and splenectomy. The predisposing causes of this autoimmune disorder, one of which is immunogenetic susceptibility, have not been fully determined. We investigated whether clinical features and human leukocyte antigen (HLA) genotypes influence the occurrence, treatment response, and disease duration of childhood ITP in Taiwan.MethodsWe performed HLA genotyping of 70 Taiwanese children with ITP and of 70 healthy controls and compared the data. Demographic data were also collected and evaluated.ResultsThe frequencies of heterozygous HLA-A11 and the HLA-Cw1 allele were both significantly decreased in the ITP group (p = 0.0160 and p = 0.0089, respectively), whereas the frequency of heterozygous HLA-DQ5 was significantly increased in the ITP group (p = 0.0057). Patients with HLA-DRB1*11 or -DRB1*15 were more likely to respond poorly to corticosteroids than IVIG (p = 0.0446 and p = 0.0008, respectively). In addition, we observed a positive association between HLA-A11 homozygosity and the development of persistent or chronic ITP [odds ratio (OR) = 6.3165, p = 0.0479]. The presence of HLA-DRB1*08 was, however, negatively correlated with the development of persistent or chronic ITP (OR = 0.1729, p = 0.0657). Children with antecedent of preceding illness (API) and with a younger age of onset were more likely to experience a better treatment response and shorter course of ITP.ConclusionWe suggest that API, age of onset, and particular HLA class I and class II alleles, may be involved in and influence the occurrence and disease duration of childhood ITP, as well as responses to different therapeutic approaches