CGD-1, a defensin-related peptide derived from marine Chinese medicine Ostreae concha, inhibits the Gram-negative bacteria by membrane attack

There is an increasing interest in discovering new antibacterial agents derived from nature to enhance the treatment of various bacterial infections.Defensins and their derived peptide fragments exhibit significant antibacterial activity without any cytotoxic effects,making them attractive features for potential novel antibacterial therapeutics.Crassostrea gigas,a traditional seafood that has been used worldwide for centuries,has its shells applied in Chinese medicine as Ostreae concha.In this study,bioinformatics analysis was used to obtain a novel antibacterial peptide,CGD-1,derived from marine Chinese medicine Ostreae concha.The physicochemical characterization and circular dichroism analysis results demonstrated that CGD-1 assembled into anα-helical structure in a simulated membrane environment,and it displayed antibacterial action against Gram-negative bacteria.The minimal inhibitory concentrations against both Pseudomonas aeruginosa ATCC27853 and Escherichia coli ATCC25922 were 25μM.CGD-1 was able to efficiently permeate the cell membrane.Changes in bacterial cell morphology were evaluated using a field emission scanning electron microscope.The results suggested that CGD-1 exerted its antibacterial activity through permeabilizing and disrupting the bacterial cell membrane.Therefore,CGD-1 may have potential applications in fighting against pathogenic bacteria such as P.aeruginosa and E.coli.

Characterization of E-cadherin expression in normal mucosa,dysplasia and adenocarcinoma of gastric cardia and its influence on prognosis

BACKGROUND Gastric cardia adenocarcinoma(GCA),which has been classified as type II adenocarcinoma of the esophagogastric junction in western countries,is of similar geographic distribution with esophageal squamous cell carcinoma in China,and even referred as"sister cancer"by Chinese oncologists.The molecular mechanism for GCA is largely unknown.Recent studies have shown that decreased expression of E-cadherin is associated with the invasion and metastasis of multiple cancers.However,the E-cadherin expression has not been well characterized in gastric cardia carcinogenesis and its effect on GCA prognosis.AIM To characterize E-cadherin expression in normal gastric cardia mucosa,dysplasia and GCA tissues,and its influence on prognosis for GCA.METHODS A total of 4561 patients with GCA were enrolled from our previously established GCA and esophageal cancer databases.The enrollment criteria included radical surgery for GCA,but without any radio-or chemo-therapy before operation.The GCA tissue from 4561 patients and matched adjacent normal epithelial tissue(n=208)and dysplasia lesions(n=156)were collected,and processed as tissue microarray for immunohistochemistry.The clinicopathological characteristics were retrieved from the medical records in hospital and follow-up was carried out through letter,telephone or home interview.E-cadherin protein expression was determined by two step immunohistochemistry.Kaplan–Meier and Cox regression analyses were used to correlate E-cadherin protein expression with survival of GCA patients.RESULTS Of the 4561 GCA patients,there were 3607 males with a mean age of 61.6±8.8 and 954 females with a mean age of 61.9±8.6 years,respectively.With the lesions progressed from normal gastric cardia mucosa to dysplasia and GCA,the positive immunostaining rates for E-cadherin decreased significantly from 100%to 93.0%and 84.1%,respectively(R2=0.9948).Furthermore,E-cadherin positive immunostaining rate was significantly higher in patients at early stage(0 and I)than in those at late stage(II and III)(92.7%vs 83.7%,P=0.001).E-cadherin positive expression rate was significantly associated with degree of differentiation(P=0.001)and invasion depth(P<0.001).Multivariate analysis showed that the GCA patients with positive E-cadherin immunostaining had better survival than those with negative(P=0.026).It was noteworthy that E-cadherin positive expression rate was similar in patients with positive and negative lymph node metastasis.However,in patients with negative lymph node metastasis,those with positive expression of E-cadherin had better survival than those with negative expression(P=0.036).Similarly,in patients with late stage GCA,those with positive expression of E-cadherin had better survival than those with negative expression(P=0.011).CONCLUSION E-cadherin expression may be involved in gastric cardia carcinogenesis and low expression of E-cadherin may be a promising early biomarker and overall survival predictor for GCA.

The Ananthakrishna Model Under Non-synchronous Perturbation

The Ananthakrishna model,seeking to explain the Portevin-Le Chatelier effect,is studied with or without non-synchronous perturbations.For the unperturbed model,Bogdanov-Takens bifurcation and zeroHopf bifurcation are detected.For the perturbed model,rich dynamical behaviors are given by researching the Poincarémap,including solutions of different periods,quasi-periodic solutions,chaotic solutions,and bistability.Moreover,an augmented temperature-dependent perturbation amplitude induces a transition from non-serrated to serrated flow on the stress-time curve.Notably,on the stress-strain curve,the phenomenon of repeated yielding diminishes with an increase in the value of a temperature-dependent parameter,while it persists with an increase in the value of a temperature-independent parameter.Sensitivity analysis sheds light on the factors exerting the most significant influence on dislocation density.

Existence of Three Positive Solutions for Quasi-linear Boundary Value Problem

In this paper, we prove a new fixed point theorem in cones and obtain the existence of triple positive solutions for a class of quasi-linear three-point boundary value problems.

Constitutive Models for Compressive Deformation of AZ80Magnesium Alloy under Multiple Loading Directions and Strain Rates

Two constitutive models,the modified Johnson-Cook model and the logarithm linear relation model based on empirical approach and data analysis,were presented to illustrate compressive deformation of magnesium alloys AZ80 under multiple loading directions and strain rates.The results of stress-strain curve analysis and sensitivity index analysis suggested that the stress held large fluctuations in loading direction of 90°.Model testing signified that the logarithm linear relation model was more proper than the modified Johnson-Cook model in view of relative mean square error and correlation coefficients.Moreover,numerical simulation building on established models also indicated that the logarithm linear model is more precise than the modified Johnson-Cook model.

Plasticity performance of Al_(0.5)CoCrCuFeNi high-entropy alloys under nanoindentation

The statistical and dynamic behaviors of the displacement-load curves of a high-entropy alloy,Al_（0.5）CoCrCuFeNi,were analyzed for the nanoindentation performed at two temperatures.Critical behavior of serrations at room temperature and chaotic flows at 200°C were detected.These results are attributed to the interaction among a large number of slip bands.For the nanoindentation at room temperature,recurrent partial events between slip bands introduce a hierarchy of length scales,leading to a critical state.For the nanoindentation at 200°C,there is no spatial interference between two slip bands,which is corresponding to the evolution of separated trajectory of chaotic behavior.