Antibacterial Activity,Cytotoxicity and Mechanisms of action of Cathelicidin Peptides against Enteric Pathogens in Weaning Piglets

In the last few decades, long-term and high-dose usage of antibiotics in livestock diets has led to the emergence of antibiotic resistant bacteria, antibiotic residues in animal products and environmental pollution, adversely affecting animal health. Because of these concerns, a study screening cathelicidin peptides from different animal origins (i.e. protegrin-1 [PG-1], PMAP-23, LL-37, indolicidin and cathelicidin-BF [C-BF]) as antibiotic replacements with higher antimicrobial activity and lower cytotoxicity was designed to study their mechanisms towards enteric pathogens in weaning piglets. PG-1 and C-BF proved to be the most effective bacteriocids with the widest spectra of activity, with the MIC values equal to or lower than commonly used antibiotics towards several Escherichia and Salmonella strains, and showed a synergistic effect with aureomycin. Mechanism studies suggested the C-BF killing mechanism is based on membrane permeability, while multiple targets maybe exist for PG-1, including membrane and intracellular biomacromolecules. Cytotoxicity tests showed PMAP-23 and C-BF exhibited the lowest cytotoxic effects, while PG-1, LL-37 and indolicidin displayed cytotoxicity by dose. This study demonstrated that among the peptides tested, C-BF has the capacity to inactivate enteric pathogens with lower cytotoxicity and is potentially a novel anti-bacterial agent. The activity of PG-1 is highly efficient, with the potential to reduce cytotoxicity using molecular design.     

Single Nanostructure Electrochemical Devices for Studying Electronic Properties and Structural Changes in Lithiated Si Nanowires

Nanostructured Si is a promising anode material for the next generation of Li‐ion batteries, but few studies have focused on the electrical properties of the Li‐Si alloy phase, which are important for determining power capabilities and ensuring sufficient electrical conduction in the electrode structure. Here, we demonstrate an electrochemical device framework suitable for testing the electrical properties of single Si nanowires (NWs) at different lithiation states and correlating these properties with structural changes via transmission electron microscopy (TEM). We find that single Si NWs usually exhibit Ohmic I–V response in the lithiated state, with conductivities two to three orders of magnitude higher than in the delithiated state. After a number of sequential lithiation/delithiation cycles, the single NWs show similar conductivity after each lithiation step but show large variations in conductivity in the delithiated state. Finally, devices with groups of NWs in physical contact were fabricated, and structural changes in the NWs were observed after lithiation to investigate how the electrical resistance of NW junctions and the NWs themselves affect the lithiation behavior. The results suggest that electrical resistance of NW junctions can limit lithiation. Overall, this study shows the importance of investigating the electronic properties of individual components of a battery electrode (single nanostructures in this case) along with studying the nature of interactions within a collection of these component structures.     

A Durable Alternative for Proton‐Exchange Membranes: Sulfonated Poly(Benzoxazole Thioether Sulfone)s

To develop a durable proton‐exchange membrane (PEM) for fuel‐cell applications, a series of sulfonated poly(benzoxazole thioether sulfone)s ( SPTESBOs) are designed and synthesized, with anticipated good dimensional stability (via acid–base cross linking), improved oxidative stability against free radicals (via incorporation of thioether groups), and enhanced inherent stability (via elimination of unstable end groups) of the backbone. The structures and the degree of sulfonation of the copolymers are characterized using Fourier‐transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy (¹H NMR and ¹⁹F NMR). The electrochemical stabilities of the monomers are examined using cyclic voltammetry in a typical three‐electrode cell configuration. The physicochemical properties of the membranes vital to fuel‐cell performance are also carefully evaluated under conditions relevant to fuel‐cell operation, including chemical and thermal stability, proton conductivity, solubility in different solvents, water uptake, and swelling ratio. The new membranes exhibit low dimensional change at 25°C to 90°C and excellent thermal stability up to 250°C. Upon elimination of unstable end groups, the co‐polymers display enhanced chemical resistance and oxidative stability in Fenton's test. Further, the SPTESBO‐HFB‐60 (HFB‐60=hexafluorobenzene, 60 mol% sulfone) membrane displays comparable fuel‐cell performance to that of an NRE 212 membrane at 80°C under fully humidified condition, suggesting that the new membranes have the potential to be more durable but less expensive for fuel‐cell applications.     

炭疽芽胞杆菌(Bacillus anthracis)检测质粒的构建及其应用

根据炭疽芽胞杆菌(Bacillus anthracis)毒性质粒pX01和pX02上的2个毒力相关基因cya和capA的序列特点,以pIJ2925为出发载体,采用一步重叠延伸PCR技术(One-step Overlap Extension PCR,简称OOE-PCR)构建了包含cya基因和capA基因保守区DNA片段的炭疽检测质粒pBIB2006。采用复合PCR对模拟炭疽危险品进行分析,结果表明pBIB2006可以为炭疽芽胞杆菌的检测提供准确、安全和方便的阳性参照品,从而为检测炭疽芽胞杆菌和炭疽芽胞杆菌灭活疫苗提供了便利。     

Aggravation Effect of Isoflurane on Aβ25–35-Induced Apoptosis and Tau Hyperphosphorylation in PC12 Cells

Some anesthetics have been suggested to induce Alzheimer??s disease (AD) neuro-pathogenesis. Increasing evidence indicates that hyperphosphorylated tau plays a key role in the pathogenic events that occur in AD. Isoflurane has been shown to induce apoptosis, which leads to accumulation of amyloid-?? (A??). We set out to investigate whether isoflurane can induce apoptosis by increasing hyperphosphorylated tau in A??_25?C35-induced cells and the underlying mechanism. Cultured rat pheochromocytoma cells (PC12) were exposed to 20?mM A??_25?C35 alone or with 2?% isoflurane for 6?h. The cell viability was determined by MTT assay, and the apoptosis rate was detected by flowcytometry. Western blotting and immunocytochemical staining were performed to observe the protein expression of Bcl-2 family, tau phosphorylation of different sites, tau protein kinases and phosphatases. Additionally, lithium chloride was administered to all above groups to investigate the changes of apoptosis rate and protein expression. The apoptosis rate was significantly increased in A??_25?C35 group compared with the others groups, which was accompanied by bcl-2 decline, and the phosphorylation of glycogen synthase kinase-3??(GSK-3??) and tau of two sites increased. LiCl attenuated the cellular apoptosis by inhibition the level of tau phosphorylation. Isoflurane upregulated the level of phosphorylated GSK-3??, which phosphorylate tau at different sites, and aggravated the apoptotic rate of the A??_25?C35-induced PC12 cells. It indicated that isoflurane-induced tau phosphorylation might play a role in the AD-like development.     

汉族马凡综合征(MFS)患者FBN1基因两种新发突变分析

为调查马凡综合征(Marfan syndrome, MFS)患者的原纤维蛋白-1(Fibrillin-1, FBN1)基因突变情况, 应用聚合酶链反应(PCR)和变性高效液相色谱法(Denaturing high-performance liquid chromatography, DHPLC)对MFS患者的FBN1基因进行突变筛查, 对DHPLC初筛异常的DNA片段进行测序分析。结果在两个MFS家系中发现FBN1基因两种新的突变: 一种为复合突变包含第55号外显子的缺失突变c.6862_6871delGGCTGTGTAG (p.Gly2288MetfsX109)、同义突变c.6861A>G和内含子的突变c.[6871+1_6871+11delGTAAGAGGATC; 6871+34dupCATCAGAAGTGACAGTGGACA]; 另一种为第20号外显子的错义突变c.2462G>A(p.Cys821Tyr)。研究表明, FBN1基因的缺失突变c.[6862_6871delGGCTGTGTAG; 6871+1_6871+11delGTAAGAGGATC] (p.Gly2288MetfsX109)和错义突变c.2462G>A(p.Cys821Tyr)可能分别是这两个家系患者的致病原因。     

术中静脉不向剂量右美托咪啶对全髋置换术患者术后患者芬太尼静脉自控镇痛效果的影响

目的：观察气管内全身麻醉下行全髋置换术患者,术中静脉应用不同剂量右美托咪定对术后芬太尼静脉自控镇痛效果的影响及相关不良反应发生的情况。方法：选择择期在气管内全麻下行全髋置换术的患者60 例,ASA Ⅰ ～Ⅱ级,年龄47～78 岁,体重42～79 kg。患者随机分组法分为3 组（n=20）：C 组（盐水对照组）、D1 组（右美托咪定0.5 μg/kg 组）和D2 组（右美托咪定1 μg/kg组）,在手术结束前约1 小时按分组分别给予生理盐水和右美托咪啶,术后镇痛使用芬太尼静脉自控镇痛24 h。记录患者术后2h、2～6 h、6～12 h、12～24 h芬太尼的用量;VAS 评分法评估患者术前、术后2 h、6 h、12 h、24 h 时的疼痛程度;记录镇痛期间恶心呕吐、皮肤瘙痒及过度镇静等不良反应发生的情况。结果：术后2h 和术后2～6 h芬太尼用量D1组和D2 组较C 组减少（P＜0.05）,但D1组和D2 组之间比较无差异（P＞0.05）;而术后6～12 和12～24 h三组患者芬太尼用量无差异（P＞0.05）。术后2 h、2～6 hVAS评分D1 组和D2 组较C组减少（P＜0.05）,而D1组和D2 组之间比较无差异（P＞0.05）;术后6～12、12～24 h三组患者VAS 评分无差异（P＞0.05）。与C 组比较,D1 组和D2 组镇痛期间恶心呕吐发生率降低（P＜0.05）,余不良反应各组之间比较无差异（P＞0.05）。结论：气管内全身麻醉下行全髋置换术的患者,术中静脉应用右美托咪啶可在术后6 h内增强芬太尼镇痛的效果减少芬太尼的用量,但增大剂量效果并不增加而作用时间也不延长。     

Equilibrium unfolding mechanism of chicken muscle triose phosphate isomerase

Triose phosphate isomerase (TIM) was prepared and purified from chicken breast muscle. The equilibrium unfolding of TIM by urea was investigated by following the changes of intrinsic fluorescence and circular dichroism spectroscopy, and the equilibrium thermal unfolding by differential scanning calorimetry (DSC). Results show that the unfolding of TIM in urea is highly cooperative and no folding intermediate was detected in the experimental conditions used. The thermodynamic parameters of TIM during its urea induced unfolding were calculated as DeltaG degrees =3.54 kcal.mol(-1), and m(G) = 0.67 kcal.mol(-1)M(-1), which just reflect the unfolding of dissociated folded monomer to fully unfolded monomer transition, while the dissociation energy of folded dimer to folded monomer is probe silence. DSC results indicate that TIM unfolding follows an irreversible two-state step with a slow aggregation process. The cooperative unfolding ratio, DeltaH(cal)/DeltaH(vH), was measured close to 2, indicating that the two subunits of chicken muscle TIM unfold independently. The van't Hoff enthalpy, DeltaH(vH), was estimated as about 200 kcal.mol(-1). These results support the unfolding mechanism with a folded monomer formation before its tertiary structure and secondary structure unfolding.     

AMPK regulates homeostasis of invasion and viability in trophoblasts by redirecting glucose metabolism: Implications for pre‐eclampsia

Pre‐eclampsia (PE) is deemed an ischemia‐induced metabolic disorder of the placenta due to defective invasion of trophoblasts during placentation; thus, the driving role of metabolism in PE pathogenesis is largely ignored. Since trophoblasts undergo substantial glycolysis, this study aimed to investigate its function and regulatory mechanism by AMPK in PE development. Metabolomics analysis of PE placentas was performed by gas chromatography–mass spectrometry (GC–MS). Trophoblast‐specific AMPKα1‐deficient mouse placentas were generated to assess morphology. A mouse PE model was established by Reduced Uterine Perfusion Pressure, and placental AMPK was modulated by nanoparticle‐delivered A769662. Trophoblast glucose uptake was measured by 2‐NBDG and 2‐deoxy‐d‐[³H] glucose uptake assays. Cellular metabolism was investigated by the Seahorse assay and GC–MS.PE complicated trophoblasts are associated with AMPK hyperactivation due not to energy deficiency. Thereafter, AMPK activation during placentation exacerbated PE manifestations but alleviated cell death in the placenta. AMPK activation in trophoblasts contributed to GLUT3 translocation and subsequent glucose metabolism, which were redirected into gluconeogenesis, resulting in deposition of glycogen and accumulation of phosphoenolpyruvate; the latter enhanced viability but compromised trophoblast invasion. However, ablation of AMPK in the mouse placenta resulted in decreased glycogen deposition and structural malformation. These data reveal a novel homeostasis between invasiveness and viability in trophoblasts, which is mechanistically relevant for switching between the ‘go’ and ‘grow’ cellular programs.

Pre‐eclampsia (PE) is associated with trophoblast AMPK hyperactivation, presumably due to LKB1 phosphorylation, and glucose uptake is consequently increased via trafficking of GLUT3 from the cytosol to the plasma membrane. Such translocation enhances glycolytic flux and redirects glucose metabolic intermediates into gluconeogenesis, resulting in PEP accumulation, which not only benefits cell survival but also suppresses invasion by repressing MMPs, and thus in turn modulates switching between the ‘go’ and ‘grow’ cellular programs.