Search

Burkholderia pseudomallei: which causes melioidosis with high mortality in humans, has become a global public health concern. Recently, infection-driven lipid droplet accumulation has been related to the progression of host-pathogen interactions, and its contribution to the pathogenesis of infectious disease has been investigated. Here, we demonstrated that B. pseudomallei infection actively induced a time-dependent increase in the number and size of lipid droplets in human lung epithelial cells and macrophages. We also found that lipid droplet accumulation following B. pseudomallei infection was associated with downregulation of PNPLA2/ATGL (patatin like phospholipase domain containing 2) and lipophagy inhibition. Functionally, lipid droplet accumulation, facilitated via PNPLA2 downregulation, inhibited macroautophagic/autophagic flux and, thus, hindered autophagy-dependent inhibition of B. pseudomallei infection in lung epithelial cells. Mechanistically, we further revealed that nuclear receptor NR1D2 might be involved in the suppression of PNPLA2 after cell exposure to B. pseudomallei. Taken together, our findings unraveled an evolutionary strategy, by which B. pseudomallei interferes with the host lipid metabolism, to block autophagy-dependent suppression of infection. This study proposes potential targets for clinical therapy of melioidosis. Abbreviations: 3-MA: 3-methyladenine; ACTB: actin beta; ATG7: autophagy related 7; B. pseudomallei: Burkholderia pseudomallei; CFU: colony-forming unit; DG: diglyceride; FASN: fatty acid synthase; GFP: green fluorescent protein; LAMP1: lysosomal associated membrane protein 1; LC-MS/MS: liquid chromatography-tandem mass spectrometry; LD: lipid droplet; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MG: monoglyceride; MOI: multiplicity of infection; mRFP: monomeric red fluorescent protein; NR1D2: nuclear receptor subfamily 1 group D member 2; p.i., post-infection; PLIN2/ADRP: perilipin 2; PNPLA2/ATGL: patatin like phospholipase domain containing 2; Rapa: rapamycin; SQSTM1/p62: sequestosome 1; shRNA: short hairpin RNA; TEM: transmission electron microscopy; TG: triglyceride

Background Helicobacter pylori (H. pylori) infection is a serious human health threat. The empiric H. pylori treatment paradigm guided by traditional testing technologies has led to antibiotic resistance. Here, we improved the qPCR method to provide technical support for precision H. pylori diagnosis and treatment. Methods Two pairs of primers and probes targeting the glmM gene were designed to detect H. pylori, and a multiplex qPCR method was established for virulence factor detection. Then, a rapid urease test (RUT), culturing and qPCR were performed on 141 specimens collected from Xinqiao Hospital of China in 2017 to evaluate the qPCR detection capability. Finally, the H. pylori infectious amount and virulence genes were detected by qPCR. Results 1. The improved qPCR method which used two pairs of primers had a higher detection rate (100%) and better accuracy (p = 0.000), compared with the qPCR using a pair of primers. It also had better consistency with the bacterial culture than with RUT (Kappa =0.440, p H. pylori infectious amount was significantly positively associated with gastritis in corpus (p = 0.003) and gastric erosion (p = 0.043). The H. pylori infectious amount in gastric precancerous patients was significantly lower than that in H. pylori-positive patients (p H. pylori-vacA s1+ amount was significantly greater than that of H. pylori-vacA s1- (p p = 0.000), peptic ulcer (p = 0.037) and gastric erosion (p = 0.009). The H. pylori-vacA+/cagA+/babA2+ frequency showed a significant positive correlation (p Conclusions The H. pylori infectious amount and presence of H. pylori virulence factors showed complex correlations with gastric disease occurrence and development. The improved qPCR with good detection performance can be used for quantitative H. pylori detection and testing for the virulence genes vacA s1, vacA m1, cagA and babA2 simultaneously. These findings will provide valuable information for disease diagnosis and treatment.

Early accurate profiling of pathogenic bacteria in patients with nosocomial bloodstream infections (nBSIs) is crucial to optimize antibiotic therapy and patient survival. We present a novel autocatalytic Multi-component DNAzyme (MNAzyme)-integrated surface plasmon resonance (SPR) biosensor assay that rapidly and sensitively detects the DNA of three nBSI pathogenic bacteria. This strategy combines autocatalytic MNAzyme cleavage on magnetic beads, as the molecular recognition and signal amplification element, with hybridization chain reaction (HCR)-mediated nanowire assembly on SPR sensing film, as the signal readout and further amplification. Once the MNAzyme complex was activated as a biocatalyst by co-recognizing the bacterial DNA and initial probes, the MNAzyme substrate was catalytically cleaved into two DNA segments. One hybridized with immobilized probes triggering folded hairpin probes to self-assemble into massive nanowire structures via HCR on the sensing interface, and the other co-recognized the initial probes trigging another cycle of multi-turnover cleavage. As a result, the amount of cleaved DNA segments was increasing and greatly enhancing the SPR signal from the analyte. This assay system can provide the fast and quantitative analysis at low concentration (67 cfu/mL of S. aureus, 57 cfu/mL of K. pneumonia and 61 cfu/mL of E. coli, respectively) in a nonenzymatic manner. More importantly, the biosensor was successfully applied to DNA extracted from clinical blood specimens of patients with nBSIs, showing good consistence and practicability. The developed autocatalytic MNAzyme-integrated SPR biosensor provides a sensitive, rapid, reliable and culture-independent approach to efficiently determine multiple pathogenic bacteria for the early diagnosis of nBSIs.

To obtain high velocity and high energy conversion efficiency on a synchronous induction coilgun, the armature capture effect which is the inherent characteristic for the synchronous induction coilgun needs to be analyzed. The reason for the armature capture effect is first deduced and analyzed using the lumped element circuit model and then quantificational result is obtained based on the field-circuit coupled model. According to the analytical result, the method to minimize the armature capture effect is proposed from the viewpoint of the magnetic coupling between the driving coil and the armature. Several ways are analyzed through the finite-element simulation. The simulation results show that adjusting the power parameters, such as increasing the capacitance or initial voltage, and decreasing the crowbar resistance, and adjusting the armature parameters, such as decreasing the mass or adopting the solenoid armature, can minimize the armature capture effect and increase the conversion efficiency. These methods are validated through a four-stage induction coilgun. We compare the simulation results with the experimental results and show that by adjusting the armature parameters, we can minimize the armature capture effect. It provides valuable reference for synchronous induction coilgun design.

Ultrafast optical Kerr effect of metallophthalocyanine-doped inorganic–organic materials was investigated using a femtosecond optical Kerr shutter at wavelength of 800 nm. Experimental results showed that the dependence of the Kerr signals on the polarization angle between the pump beam and the probe beam could be controlled by changing the pump-probe intensity ratio. The pump-intensity dependence of the polarization characters of the Kerr signals probably arose from the contribution of light induced transient grating (LITG) to the Kerr signals.

In order to obtain high velocity and high energy conversion efficiency on synchronous induction coilgun, the armature capture effect which is the inherent characteristic for the coilgun need to be analyzed. The reason for armature capture effect is firstly deduced and analyzed through lumped-element circuit model, and then the quantificational result is obtained based on the field-circuit coupled model. According to the analytic result, the method to minimize the armature capture effect is proposed from the viewpoint of the magnetic couple between the driving coil and armature. Several measures are analyzed through the finite element simulation. The simulation result shows that adjusting the power parameters, such as adding the capacitance or initial voltage, and decreasing the crowbar resistance, and adjusting armature parameters, such as decreasing the mass or changing the structure, can minimize the armature capture effect and increase the system efficiency. The measures are validated through a 4-stage induction coilgun. Comparing the experimental result with the simulation result, adjusting the armature parameter which minimizes the armature capture effect accords with the fact well. It provides valuable reference for induction coilgun design.

Using the optical Kerr shutter (OKS) technique with an 800-nm femtosecond laser, we demonstrated that the response time of the glass was less than 85 fs. The nonlinear refractive-index of Bi2O3-B2O3-SiO2 (BI) oxide glass was estimated to be about 2.93times10- 15cm2/W. By measuring the dependence of the OKS signals on the pump power and on the polarization angle between pump and probe beams, we found that the OKS signals arose mainly from the photoinduced birefringence effect, and the polarization dependence of the signals was dependent on the intensity ratio of the pump beam to the probe beam.

We investigated influence of the self-diffraction effect on optical Kerr signals of Bi2O3-B2O3-SiO2 glass (BI glass) and CS2 in femtosecond non-collinear pump-probe optical Kerr experiments. By measuring the dependence of the Kerr signals on the pump power and on the polarization angle between pump and probe beams, we found that the optical Kerr signals of CS2 consisted of two components: a fast response and a slow response, which were attributed to the self-diffraction effect and the photoinduced birefringence effect, respectively. The contribution of the self-diffraction effect to the Kerr signals increased with increase of the pump power. For the BI glass, no evident influence of self-diffraction on the Kerr signals was observed.