Silibinin attenuates Streptococcus suis serotype 2 virulence by targeting suilysin

AIMS

To determine the antivirulence properties of silibinin against suilysin (SLY), a virulence factor of Streptococcus suis serotype 2 (SS2) that plays an important role in the pathogenesis of S. suis infection and its protective effect against SS2 infection in a mouse model.

METHODS AND RESULTS

Susceptibility testing, haemolysis assay and Western blot assays were employed to evaluate the performance of silibinin on SLY pore-forming activity. Cytotoxicity assays and mouse infection tests were also performed to determine the efficacy of silibinin against SS2 infection. The results showed that silibinin, a flavonoid with little anti-S. suis activity, was identified to be a potent antagonist of SLY-mediated haemolysis through the inhibition of its oligomerization. Treatment with silibinin reduced S. suis-induced cytotoxicity in macrophages (J774 cells). In addition, S. suis-infected mice that received silibinin showed a lower bacterial burden.

CONCLUSIONS

Our results demonstrated that silibinin is a promising candidate for the development of antivirulence therapeutic agents to treat S. suis infections.

SIGNIFICANCE AND IMPACT OF THE STUDY

The antivirulent property of silibinin against SS2 by targeting SLY provides the possibility for the future pharmaceutical application of silibinin to prevent and treat S. suis infection.

Application of High-throughput Sequencing in Researches of Cadaveric Microorganisms and Postmortem Interval Estimation

Necrobiome is the main factor causing the cadaver decomposition. Studying the microbial succession during decomposition is one of the main tasks of forensic microbiology. The interactive relationships among cadaver, environment and microorganisms are complicated. The microbial succession study relies on macroscopic monitoring of community composition and the diversity change in each decomposition stage. With the maturity and development of high-throughput sequencing （HTS）, the structure and diversity of microbial communities in different environments have been successively revealed. A new breakthrough to explore the cadaveric microorganisms has been opened as well. It has become the research hotspots in forensic microbiology to reveal the microbial succession in the process of cadaver decomposition and to interpret the essence of various decomposition phenomena by using HTS, which can provide a new reference for postmortem interval （PMI） estimation. The present paper reviews studies on PMI estimation by using cadaveric microorganism. Problems and application prospects of forensic microbiology studies are discussed on the basis of the current application of HTS technology in the exploration of microbial succession.

Enhanced energy gain in a dielectric laser accelerator using a tilted pulse front laser

Using an 800 nm, 45 fs pulse-front-tilted laser we demonstrate a record 315 keV energy gain in a dual grating dielectric laser accelerator (DLA) and average accelerating gradients of 560 MV/m over 0.5 mm. These results open a new regime in DLA characterized by significant evolution of the beam distribution in the longitudinal phase space, corresponding to > 1/4 of a synchrotron oscillation. By tilting the laser wavefront we control the resonant velocity of the DLA and observe a net energy gain, indicating that a tapered optical phase could be used to achieve very high energy gain.

Determination of the electron-lattice coupling strength of copper with ultrafast MeV electron diffraction

Electron-lattice coupling strength governs the energy transfer between electrons and the lattice and is important for understanding the material behavior under highly non-equilibrium conditions. Here we report the results of employing time-resolved electron diffraction at MeV energies to directly study the electron-lattice coupling strength in 40-nm-thick polycrystalline copper excited by femtosecond optical lasers. The temporal evolution of lattice temperature at various pump fluence conditions were obtained from the measurements of the Debye-Waller decay of multiple diffraction peaks. We observed the temperature dependence of the electron-lattice relaxation time which is a result of the temperature dependence of electron heat capacity. Comparison with two-temperature model simulations reveals an electron-lattice coupling strength of (0.9 ± 0.1) × 10¹⁷ W/m³/K for copper.

An interlocked flexible piezoresistive sensor with 3D micropyramidal structures for electronic skin applications

The development of flexible pressure sensors with human-like sensing capabilities is an emerging field due to their wide range of applications from human robot interactions to wearable electronics. Piezoresistive sensors respond to externally induced mechanical stimuli through changes in their electrical resistance. The current state-of-the-art piezoresistive sensors are mainly constructed via dispersion of conductive nanofillers in an elastomer matrix making their performance strongly reliable on the degree of dispersion. Alternatively, changes in the contact area of conductive elastomers result in higher sensitivity and more tunable variables. Herein, an interlocked sensor comprising two flexible layers of 3D pyramidal microstructures is fabricated with a thin layer of carbon nanotubes deposited onto the micropatterns. The introduced array of micropyramids with varying height and pitch sizes allows for higher changes in the contact area upon applying an external load. The results indicate that the height and pitch of the structures together with a newly defined variable, the critical dimension, affect the sensor's sensitivity. An optimal performance is observed for minimized values of the critical dimension. Furthermore, to verify the obtained results, a finite-element-assisted analytical constriction-resistance model is used to capture the piezoresistive response of the sensor. The theoretical results show the high tracking ability of their experimental counterparts.

Hepatic phosphorylation status of serine/threonine kinase 1, mammalian target of rapamycin signaling proteins, and growth rate in Holstein heifer calves in response to maternal supply of methionine

The study investigated whether methionine supply during late pregnancy is associated with liver mammalian target of rapamycin (MTOR) pathway phosphorylation, plasma biomarkers, and growth in heifer calves born to cows fed a control diet (CON) or the control diet plus ethylcellulose rumen-protected methionine (MET; 0.09% of dry matter intake) for the last 28 d prepartum. Calves were fed and managed similarly during the first 56 d of age. Plasma was harvested at birth and 2, 7, 21, 42, and 50 d of age and was used for biomarker profiling. Liver biopsies were harvested at 4, 14, 28, and 50 d of age and used for protein expression. Body weight, hip height, hip width, wither height, body length, rectal temperature, fecal score, and respiratory score were measured weekly. Starter intake was measured daily, and average daily gain was calculated during the first 8 wk of age. During the first 7 wk of age, compared with calves in the CON group, calves in the MET group had greater body weight, hip height, wither height, and average daily gain despite similar daily starter intake. Concentration of methionine in plasma was lower at birth but increased markedly at 2 and 7 d of age in MET calves. Plasma insulin, glucose, free fatty acids, and hydroxybutyrate did not differ. A greater ratio of phosphorylated α-serine/threonine kinase (AKT):total AKT protein expression was detected in MET calves, namely due to differences at 4 d of age. The phosphorylated MTOR:total MTOR ratio also was greater in MET calves due to differences at 28 and 50 d (8 d postweaning). The decrease in phosphorylated MTOR:total MTOR between 14 and 28 d in CON calves agreed with the increase in phosphorylated eukaryotic translation initiation factor 4E binding protein 1 (EIF4EBP1):total EIF4EBP1 ratio during the same time frame. The overall expression of phosphorylated ribosomal protein S6 kinase B1 (RPS6KB1):total RPS6KB1 and phosphorylated eukaryotic translation elongation factor 2 (EEF2):total EEF2 was lower in MET calves. Regardless of methionine supply prepartum, there was an 11-fold temporal decrease from 4 to 50 d in phosphorylated AKT:total AKT. Similarly, regardless of methionine supply, there were overall decreases in phosphorylation ratios of AKT, MTOR, RPS6KB1, and eukaryotic translation initiation factor 2A (EIF2A) over time. Data provide evidence of a positive effect of methionine supply during the last month of pregnancy on rates of growth during the first 7 wk of age. Phosphorylation status of some components of the MTOR pathway in neonatal calf liver also was associated with greater maternal supply of methionine. Thus, the data suggest that molecular mechanisms in the liver might be programmed by supply of methionine during late pregnancy. The exact mechanisms coordinating the observed responses remain to be determined.

Factors Associated With Prolonged Viral Shedding in Patients With Avian Influenza A(H7N9) Virus Infection

Background

Data are limited on the impact of neuraminidase inhibitor (NAI) treatment on avian influenza A(H7N9) virus RNA shedding.

Methods

In this multicenter, retrospective study, data were collected from adults hospitalized with A(H7N9) infection during 2013-2017 in China. We compared clinical features and A(H7N9) shedding among patients with different NAI doses and combination therapies and evaluated factors associated with A(H7N9) shedding, using Cox proportional hazards regression.

Results

Among 478 patients, the median age was 56 years, 71% were male, and 37% died. The median time from illness onset to NAI treatment initiation was 8 days (interquartile range [IQR], 6-10 days), and the median duration of A(H7N9) RNA detection from onset was 15.5 days (IQR, 12-20 days). A(H7N9) RNA shedding was shorter in survivors than in patients who died (P < .001). Corticosteroid administration (hazard ratio [HR], 0.62 [95% confidence interval {CI}, .50-.77]) and delayed NAI treatment (HR, 0.90 [95% CI, .91-.96]) were independent risk factors for prolonged A(H7N9) shedding. There was no significant difference in A(H7N9) shedding duration between NAI combination treatment and monotherapy (P = .65) or between standard-dose and double-dose oseltamivir treatment (P = .70).

Conclusions

Corticosteroid therapy and delayed NAI treatment were associated with prolonged A(H7N9) RNA shedding. NAI combination therapy and double-dose oseltamivir treatment were not associated with a reduced A(H7N9) shedding duration as compared to standard-dose oseltamivir.

miR-181c-3p and -5p promotes high-glucose-induced dysfunction in human umbilical vein endothelial cells by regulating leukemia inhibitory factor

Diabetes mellitus is a chronic metabolic disease with high blood glucose level and closely related to endothelial dysfunction, an important factor in the pathogenesis of vascular changes. Several miRNAs have been reported to be altered in a diabetic environment including miR-181c. In the article, we found that the expression of miR-181c-3p and miR-181c-5p was significantly downregulated under glucose treatment in a dose-dependent manner and in peripheral blood from diabetic patients compared with healthy participants. We explored the role of miR-181c-3p and miR-181c-5p in high glucose (HG)-induced dysfunction in human umbilical vein endothelial cells (HUVECs) by regulating leukemia inhibitory factor (LIF), their potential target with binding sites in 3-UTR region, that is also closely related to glucose metabolism. In addition, miR-181c-3p and miR-181c-5p significantly enhanced HG-induced oxidative stress injury by increasing malondialdehyde (MDA) and reactive oxygen species (ROS) production and promoted HG-induced HUVECs apoptosis, confirmed by TUNEL staining. LIF partially reduced those effects by decreasing oxidative stress and inhibiting cell apoptosis. Therefore, knocking down of LIF in HUVECs by LIF siRNA transfection, significantly increased HG-induced MDA and ROS production and induced more intense HUVECs apoptosis. Our results indicate that miR-181c-3p and miR-181c-5p promote HG-induced HUVECs injury through their target LIF.

Effects of gamma radiation on microbial, physicochemical, and structural properties of whey protein model system

Gamma radiation has been used in food processing for many years, though it has certain effects on food components. Whey protein solutions (10%/30%, wt/vol) were treated with gamma radiation at various dosages (10-25 kGy) and evaluated for microbial changes in the solutions and physicochemical and structural changes of whey proteins. Whey protein solutions after gamma radiation showed substantially lower populations of all viable microorganisms than those of controls. The 10% whey protein solution treated at radiation of 20 or 25 kGy remained sterile for up to 4 wk at room temperature. Gamma radiation increased viscosity and turbidity and decreased soluble nitrogen of whey protein solutions compared to nonradiated control samples regardless of radiation dosage. Nonreducing sodium dodecyl sulfate-PAGE suggested that whey proteins under gamma radiation treatment formed aggregates with high molecular weights. Reducing sodium dodecyl sulfate-PAGE showed that disulfide bonds played a role in gamma radiation-induced whey protein cross-linking. Scanning and transmission electron microscopy micrographs exhibited large aggregates of whey proteins after gamma radiation treatment. Results suggested that gamma radiation could be applied to whey protein solution for purposes of reducing microbial counts and cross-linking protein molecules.

Beyond a phenomenological description of magnetostriction

Magnetostriction, the strain induced by a change in magnetization, is a universal effect in magnetic materials. Owing to the difficulty in unraveling its microscopic origin, it has been largely treated phenomenologically. Here, we show how the source of magnetostriction-the underlying magnetoelastic stress-can be separated in the time domain, opening the door for an atomistic understanding. X-ray and electron diffraction are used to separate the sub-picosecond spin and lattice responses of FePt nanoparticles. Following excitation with a 50-fs laser pulse, time-resolved X-ray diffraction demonstrates that magnetic order is lost within the nanoparticles with a time constant of 146 fs. Ultrafast electron diffraction reveals that this demagnetization is followed by an anisotropic, three-dimensional lattice motion. Analysis of the size, speed, and symmetry of the lattice motion, together with ab initio calculations accounting for the stresses due to electrons and phonons, allow us to reveal the magnetoelastic stress generated by demagnetization.

Effects of monoclonal antibodies against PCSK9 on clinical cardiovascular events : A meta-analysis of randomized controlled trials

BACKGROUND

The present meta-analysis was designed to improve statistical power and review the effects of monoclonal antibodies against PCSK9 on clinical cardiovascular events.

METHODS

PubMed, Embase, Web of Science, and the Cochrane Library were searched from inception to May 2017. Studies considered to be eligible were randomized controlled trials about the effects of monoclonal antibodies against PCSK9 on clinical cardiovascular events. The primary endpoint was positively adjudicated cardiovascular events; the secondary endpoint comprised cardiac mortality, myocardial infarction (MI), coronary revascularization, stroke, and hospitalization for unstable angina.

RESULTS

We included 20 randomized controlled trials involving 67,934 patients. Monoclonal antibodies against PCSK9 were associated with a significant reduction in positively adjudicated cardiovascular events (relative risk [RR] = 0.87; 95% confidence interval [CI] = 0.81-0.93; z = 4.03; p = 0.000), MI (RR = 0.78; 95% CI = 0.71-0.86; z = 4.96; p = 0.000), coronary revascularization (RR = 0.81, 95% CI = 0.75-0.88; z = 4.93; p = 0.000), and stroke (RR = 0.76, 95% CI = 0.65-0.89; z = 3.47; p = 0.001). Monoclonal antibodies against PCSK9 did not reduce hospitalization rates due to unstable angina. The results of subgroup analysis showed that evolocumab was associated with a lower risk of positively adjudicated cardiovascular events, MI, coronary revascularization, and stroke without reducing cardiac mortality. Alirocumab reduced the incidence of cardiac mortality but not of other cardiovascular events, while bococizumab was associated with a reduced risk of stroke.

CONCLUSION

Monoclonal antibodies against PCSK9 were associated with a lower risk of positively adjudicated cardiovascular events, MI, coronary revascularization, and stroke.