Advances in Research on Resistance Mechanisms of Bacterial Biofilms

A biofilm refers to a group of organized bacteria attached to the surface of living or inanimate objects and surrounded by some macromolecules. It is rich in organic components such as polysaccharides,peptides and phospholipids,greatly increases the resistance of bacteria to antibacterial drugs,and can cause infections in humans and animals. At present,the measure to prevent the infections is to prevent microbial colonies from adhering to the surface of the objects,which will help to improve the therapeutic effect of clinically serious infectious diseases. In addition,the identification and inhibition of biofilm formation genes is also an important research direction to control such infections. In this paper,molecular mechanisms of bacterial biofilm resistance to drugs that has caused widespread concern were summarized.

Anti-Biofilm, Anti-Quorum Sensing, and Anti-Proliferative Activities of Methanolic and Aqueous Roots Extracts of Carica papaya L. and Cocos nucifera L.

Objective: This study focused on the antibacterial and anti-proliferative activity of extracts from Carica papaya and Cocos nucifera roots. Methodology: The minimum inhibitory concentration and the minimum bactericidal concentration of the extracts on Escherichia coli, Pseudomonas aeruginosa, Streptococcus mutans, and Staphylococcus aureus were deduced by the microdilution method. The anti-biofilm activity was determined on all four strains and anti-quorum sensing activity by inhibition of violacein production in Chromobacterium violaceum. Anti-proliferative activity on prostate cultured cancer cells was evaluated by MTT assay. Sterols and triterpenes were also assayed in this study. Results: The methanolic extract of Carica papaya showed the best anti-biofilm effect with a percentage inhibition of 66.10 ± 1.79. The methanolic extract of Cocos nucifera had the strongest inhibition on the production of quorum sensing (61.42 ± 0.28). In addition, the methanolic extract of Cocos nucifera roots showed the best cytotoxic effect on prostate cancer LNCaP cell lines (IC50 = 26.98 ± 2.6 μg/mL) and Carica papaya on the PC-3 lines (IC50 = 127.20 ± 5.99 μg/mL). The extracts were also rich in triterpenes and sterols. Conclusion: This study provides support for the ethnomedical use of Carica papaya and Cocos nucifera roots as an antimicrobial and anticancer.

On the Construction of Deepening Anti - corruption Mechanism

It needs the foundation of system and the guarantee of organizational system for anti-corruption,but it is more necessary to build and form an effective anti-corruption mechanism,so that the anti-corruption can be really put into practice. Anti-corruption mechanism refers to a organic operation system of the interaction,interconnection and constraint between the constituent elements( parts) and elements of national anti-corruption,and as a system,anti-corruption mechanism should have the characteristics of system aticness,comprehensiveness,transparency,legalization,public participation,scientific dynam ic,and internationalism. The construction of deepening anti-corruption mechanism is the need for reconstructing the ruling legitimacy of the party and the governm ent. Adhering to the principle of treating both root causes and symptoms is necessary in the construction of anti-corruption m echanism,com bating and punishing corruption is an important part of anti-corruption,and the prevention and control of corruption is the basic project of anti-corruption. Therefore,the construction of prevention and control mechanism in the anti-corruption mechanism has a more far-reaching significance.

Study on Formation and Inhibition Mechanism of Biofilm of Pig Actinobacillus pleuropneumoniae

Pig Actinobacillus pleuropneumoniae(App) could induce chronic respiratory tract infection in pigs, which causes major economic losses on pig industry. Bacterial biofilm(BBF) is bacterial community adsorbed on the surface of biomaterials or body cavity, to protect bacteria escape, and recurrent outbreaks of related infectious diseases and chronic infections resulting therefrom are called bacterial biofilm diseases. App BF belongs to polymers with spatial structure in vitro, and its formation is regulated by multiple genes. Among them, gene deletion of the key component TolC of multidrug efflux pumps and type I secretion systems causes that App BF adhesion weakens; gene deletion of catalytic core ClpP of Clp proteolytic complex induces the inhibition of BF formation; outer membrane lipoprotein VacJ of App promotes BF formation; gene deletion of active enzyme LuxS enhances the formation of App BF and decreases bacterial adhesion ability; gene deletion of Adh obviously declines bacterial accumulation, BF formation and adhesion to host cells. In this paper, BF formation or inhibition mechanism in App is elaborated from molecular level, which could provide reference basis for exploring the prevention of its biofilm diseases.

Advances in Research on Anti-cancer Mechanism of 18β Glycyrrhetinic Acid

Glycyrrhiza uralensis Fisch has been used to treat the symptoms of organ fever, food poisoning, typhoid fever, sore throat, cough due to lung heat, children's diseases and so on since the ancient times. It is a solid Chinese herbal medicine which is good for the health. In recent years, it has been found that licorice extract also has excellent anti-cancer effect. The 18β glycyrrhetinic acid, obtained by hydrolysis of precursor glycyrrhizic acid, is a relatively efficient anti-cancer ingredient. 18β glycyrrhetinic acid can exert anti-cancer effects by inhibiting cancer cell proliferation, inducing apoptosis of cancer cells, inhibiting invasion and metastasis of cancer cells, preventing oxidation, inhibiting neovascularization, inhibiting lymphangiogenesis, and regulating hormone secretion. This paper reviewed the advances in research of the anticancer mechanism of 18β glycyrrhetinic acid, to provide a theoretical basis for future research.

Study about anti-request design of transmission mechanism in job device of colliery sump cleaner

The paper takes reversal hexagon connecting bar mechanism which uses in colliery sump cleaner as research object, takes main performance of reversal hexagon connecting bar in loader as target and uses the idea of anti request project and modern design, raises a new method of engineering design. It has proved that the method is feasibility and correct by practice.

Acinetobacter baumannii biofilm resistance mechanisms and prevention and control of progress

At present,the multiple drug resistance of Acinetobacter baumannii outbreaks worldwide and has intensified the trend,especially in the intensive care unit and burn ward.Generic drug resistant Acinetobacter baumannii is known as the 21st century gram-negative bacterium“MRSA”,“Superbugs”.In recent years,researches have shown that this is associated with pathogenic bacteria to form biofilms.In this paper,the status of Acinetobacter baumannii infection,biofilm formation,resistance mechanism and prevention in recent years were summarized.

Anti-oxidation mechanism of SiC-B_4C-C composites

Mixture of green petroleum coke, B4C and SiC together with short carbon fiber were employed as starting materials, the mixture was press-formed without any binder after grinding, dense and homogeneous binderless SiC-B4C-C（carbon/ceramic） composites were then obtained after sintering. Composites thus prepared possess excellent anti-oxidation property, that is, mass loss less than 1% within the temperature range from 900 to 1100℃ for 10h. Anti-oxidation mechanism was also discussed from the viewpoint of thermodynamics, excellent anti-oxidation property of materials thus prepared can be discribed to 1) solid SiO2 formed from SiC, which restrains the filtering of oxygen and simultaneously, its volume expansion brought about by the reaction takes roles both walling up the （original） pores and making the material more compact; 2) liquid B2O3 from the reaction of B4C not only makes the combination with C, B4C and SiC tighter through forming solid solution, but also effect of reaction SiC（s）+2CO（g）=SiO2（s）+3C（s） is an expansive process, which improves the microstructure of the material.

Anti-Fertility Effects and Mechanism of the Plant Extract Shikonin on Mice

Controlling fertility of rodent pests has become an effective means of controlling the population of grassland rodents in China. Recently, research has focused on how to select environmentally-friendly sterilants without pollution effects, and to realize sustainable control of pest rodent populations. Sterilants from plant extracts have been mainly selected. In this study, mice were used as the experimental subjects for research on the anti-fertility effects of plant extracts of shikonin and the anti-fertility mechanism of shikonin extract was determined. The mice were divided into four groups, including one control group and three experimental groups. There were three applications of shikonin extract in different concentrations (5 mg·kg-1, 20 mg·kg-1 and 50 mg·kg-1). The mice gavage experiments indicated that a shikonin concentration of 50 mg·kg-1 had the expected anti-fertility effects. Mice copulation experiments showed that the 50 mg·kg-1 shikonin treatment had significant anti-fertility effects on both female-treatment and female-male-treatment groups. The results of the PCR analysis on the AgRP and ghrelin mRNA from female ovaries and male testicles indicated that shikonin could control mice reproduction by regulating the pituitary gonadal axis. Shikonin, as plant source sterile agent, would have more ideal effects for functioned both sexes sterility.

Design and Analysis of Electro-mechanical Hybrid Anti-lock Braking System for Hybrid Electric Vehicle Utilizing Motor Regenerative Braking

Braking on low adhesion-coefficient roads, hybrid electric vehicle＇s motor regenerative torque is switched off to safeguard the normal anti-lock braking system （ABS） fimction. When the ABS control is terminated, the motor regenerative braking is readmitted. Aiming at avoiding permanent cycles from hydraulic anti-lock braking to motor regenerative braking, a novel electro-mechanical hybrid anti-lock braking system using fuzzy logic is designed. Different from the traditional single control structure, this system has a two-layered hierarchical structure, The first layer is responsible for harmonious adjustment or interaction between regenerative system and anti-lock braking system. The second layer is responsible for braking torque distribution and adjustment. The closed-loop simulation model is built. Control strategy and method for coordination between regenerative and anti-lock braking are developed. Simulation braking on low adhesion-coefficient roads with fuzzy logic control and real vehicle braking field test are presented. The results from simulating analysis and experiment show braking performance of the vehicle is perfect, harmonious coordination between regenerative and anti-lock braking function, significant amount of braking energy can be recovered and the proposed control strategy and method are effective.

In vitro anti-biofilm and anti-bacterial activity of Junceella juncea for its biomedical application

Objective:To investigate the anti-biofilm and anti-bacterial activity of Junceella juncea(J.juncea)against biofilm forming pathogenic strains.Methods:Gorgonians were extraeted with methanol and analysed with fourier transform infrared spectroscopy.Biofilm forming pathogens were identified by Congo red agar supplemented with sucrose.A quantitative spectrophotometric method was used to monitor in vitro biofilm reduction by microtitre plate assay.Anti-bacterial activity of methanolic gorgonian extract(MGE)was carried out by disc diffusion method followed by calculating the percentage of increase with crude methanol(CM).Results:The presence of active functional group was exemplified by FT-IR spectroscopy.Dry,black,crystalline colonies confirm the production of extracellular polymeric substances responsible for biofilm formation in Congo red agar.MGE exhibited potential anti-biofilm activity against all tested bacterial strains.The anti-bacterial activity of methanolic extract was comparably higher in Salmonella typhii followed by Escherichia colt,Vibrio cholerae and Shigella flexneri.The overall percentage of increase was higher by 50.2%to CM.Conclusions:To conclude,anti-biofilm and anti-bacterial efficacy of J.juncea is impressive over biofilm producing pathogens and are good source for novel anti-bacterial compounds.

Numerical simulation of solid tumor angiogenesis with Endostatin treatment:a combined analysis of inhibiting effect of anti-angiogenic factor and micro mechanical environment of extracellular matrix

To investigate the influence of anti-angiogenesis drug Endostatin on solid tumor angiogenesis, a mathematical model of tumor angiogenesis was developed with combined influences of local extra-cellular matrix mechanical environment, and the inhibiting effects of Angiostatin and Endostatin. Simulation results show that Angiostatin and Endostatin can effectively inhibit the process of tumor angiogenesis, and decrease the number of blood vessels in the tumor. The present model could be used as a valid theoretical method in the investigation of anti-angiogenic therapy of tumors.

Effect of inertial acoustic cavitation on antibiotic efficacy in biofilms

Bacterial biofilms can lead to chronic infections,increase tolerance to antibiotics and disinfectants,resistance to phagocytosis,and other components of the body’s immune system.Biofilm formation is implicated in the persistence of staphylococcal infections and chronic Pseudomonas aeruginosa lung infections in cystic fibrosis(CF)patients(which can result from biofilm-growing mucoid strains).Conventional treatments utilize aggressive antibiotic prophylaxis/therapy to prevent/eliminate biofilms,followed by chronic suppressive therapy.Recently,the use of enzymes to dissolve the biofilm matrix was investigated,in addition to quorum sensing inhibitors to increase biofilm susceptibility to antibiotics.Here,we propose a novel strategy,utilizing ultrasound-induced inertial cavitation,to increase antibiotic efficacy.The wall shear stress at the biofilm interface is calculated,and viscoplastic constitutive equations are used to examine the biofilm response to the mechanical stress.Our simulations suggest that the maximum biofilm detachment occurs at high pressure/low frequency,and the mechanical disruption can affect the biochemical processes inside the biofilm resulting in vulnerability to antibiotics.

Numerical investigation of unsteady mixing mechanism in plate film cooling

A large-scale large eddy simulation in high performance personal computer clusters is carried out to present unsteady mixing mechanism of film cooling and the development of films. Simulation cases include a single-hole plate with the inclined angle of 30° and blowing ratio of 0.5, and a single-row plate with hole-spacing of 1.5D and 2D （diameters of the hole）. According to the massive simulation results, some new unsteady phenomena of gas films are found. The vortex system is changed in different position with the development of film cooling with the time marching the process of a single-row plate film cooling. Due to the mutual interference effects including mutual exclusion, a certain periodic sloshing and mutual fusion, and the structures of a variety of vortices change between parallel gas films. Macroscopic flow structures and heat transfer behaviors are obtained based on 20 million grids and Reynolds number of 28600.

Determination of the Anti-Adhesive and Anti-Biofilm Capacity of a Wheat Extract on <i>Staphylococcus aureus</i>in Farms

The formation of biofilm by pathogenic microorganisms has become a problem in the livestock industry since it is considered a potential source of infection for farm animals while increasing microbial resistance to physical and chemical agents. Some plant extracts, such as soluble wheat extract, have been shown to be effective in inhibiting or destroying the biofilm of certain micro-organisms under specific conditions. The objective of this study is to evaluate the capacity of the pathogen to form biofilm on different surfaces used in livestock, as well as to evaluate the anti-biofilm capacity of the soluble wheat extract against S. aureus on these surfaces. The inhibition potential of inhibition or destruction of biofilm was tested in vitro. Wheat extract at a concentration of 0.29 mg/100mL showed anti-biofilm activity on S. aureus, inhibiting its formation, as well as destroying it greatly after a contact time of 24 hours, on those surfaces where the microorganism presents more adhesion capacity.

Research Progress on Molecular Mechanism of Moxibustion in the Treatment of Ankylosing Spondylitis

As an important part of traditional Chinese medicine (TCM) nursing technology, moxibustion plays a unique role in improving the symptoms of ankylosing spondylitis (AS). The research on the mechanism of moxibustion intervention in AS mainly focuses on anti-inflammatory effects, immune regulation, bone metabolism regulation, intestinal flora regulation, and so on. Molecular medicine is of great significance to further clarify the mechanism of moxibustion intervention in AS. However, there are still some problems in the research on the molecular mechanism of moxibustion intervention in AS: the existing biomedical research methods only explore from a specific field and lack the exploration of moxibustion-targeted molecules based on biomedical network. In the future, the molecular network effect of moxibustion on AS can be discussed comprehensively and systematically with the help of omics technology and the construction of biological information interaction network between omics. The effect of moxibustion on upstream osteogenic transcription factors and related signaling pathways such as WNT, β-catenin, and BMP/Smads is not yet clear. Future research can focus on the relevant signal targets of bone reconstruction and clarify the mechanism of moxibustion against the new bone formation. In addition, there is a lack of research on the molecular mechanism of moxibustion in the treatment of AS from the perspective of metabolites. It is necessary to further explore the mechanism of moxibustion in the treatment of AS with the help of metabonomics technology.

麦冬抗肿瘤作用机制研究进展

麦冬是我国的传统中药,具有养阴生津、润肺清心的功效。越来越多的研究发现,麦冬除了传统功效外还具有对多种肿瘤的抑制作用。麦冬可通过抑制肿瘤细胞增殖、诱导肿瘤细胞凋亡、坏死性凋亡、铁死亡、焦亡、自噬、细胞周期阻滞、抑制肿瘤细胞转移和血管生成以及逆转肿瘤细胞耐药性等多种机制发挥抗肿瘤作用。对近年来麦冬块根提取物及其活性单体的抗肿瘤作用研究进展进行综述,为麦冬抗肿瘤的深入研究和对麦冬的进一步开发利用提供可借鉴的思路和方向。

爱媛类芽孢杆菌抗菌肽对白色念珠菌生物膜的抑制作用机制

研究爱媛类芽孢杆菌抗菌肽对白色念珠菌生物膜的抑制作用,采用微量二倍稀释法和时间-杀菌曲线测定抑制效果,显微镜观察对白色念珠菌芽管和菌丝形成的影响,2,3-二(2-甲氧基-4-硝基-5-磺酸基苯基)-2H-四唑-5-甲酰苯胺法研究对生物膜、预成型生物膜形成和成熟生物膜清除率的影响,荧光探针观察对生物膜结构和膜内菌体状态的影响,平板涂布法和实时聚合酶链式反应测定生物膜内活菌数量和相关基因表达水平。结果表明,抗菌肽对白色念珠菌的最小抑菌浓度为8.28 AU/mL。抗菌肽能降低白色念珠菌的芽管形成率,阻止菌丝的生成,使其以酵母形式存在。抗菌肽对生物膜的形成和清除产生影响,能在较短时间内破坏生物膜的结构完整性,导致菌体受损和死亡,减少膜内菌落数量。在基因水平上,抗菌肽可降低多个生物膜形成相关的基因(如ALS1、ALS3、HWP1、EFG1、ECE1和UME6)的表达水平,从而抑制生物膜的形成。研究证明抗菌肽能够有效抑制白色念珠菌生物膜形成、成熟膜清除、成膜基因表达等,结果可为白色念珠菌新型抑菌物质的开发奠定理论基础,为食品病原微生物污染防治和食品质量安全保障提供依据。

甘草抗炎活性物质基础及其作用机制研究进展

炎症是机体对于刺激所产生的一种防御反应,随着炎症的发展可能导致组织的变异和增生,进一步加剧疾病的进程。甘草作为“众药之王”“国之药老”,早在《神农本草经》中就记载其清热作用较强,能“主五脏六腑寒热邪气”。现代研究表明,甘草提取物对肾小球肾炎、结肠炎症状改善明显,甘草及其制剂在治疗肝炎、胃炎、支气管炎、心肌炎、强直性脊柱炎等炎症性疾病方面亦具有一定的独特优势和发展潜力。该文旨在通过对近期国内外甘草抗炎活性物质基础及其作用机制方面的相关文献进行收集和整理,探索甘草发挥抗炎作用的主要活性成分及靶点通路,以期为甘草抗炎作用的进一步研究及抗炎药物的研发提供思路和参考。

道路沥青紫外老化及抗老化材料研究综述

道路沥青材料在使用过程中由于长期受到太阳光紫外辐射作用会产生紫外老化现象,并且这种现象在紫外辐射强度高的地区更明显。紫外老化会使沥青的物理特性和化学组成发生改变,从而导致沥青黏塑性上升、低温和疲劳性能下降、使用裂缝增加,进而劣化路面的耐久性、影响沥青路面的运营品质和服役寿命。为了防止和延缓紫外老化的产生和发展,可在道路沥青中添加抗老化材料以增强其抵御紫外老化能力,同时延长沥青路面的使用寿命并降低其性能的衰变速率。本文阐述了基于自由基和胶体理论的紫外老化机理;从处理方式、光源与辐射强度选择等方面介绍了室内模拟老化试验条件;总结了紫外老化对沥青物理和流变性能、组分构成、微观形貌、特征峰和官能团等宏微观特性的影响;归纳了现行抗老化材料的优缺点和使用情况。分析表明后期可在老化机理深度、试验方法标准化、室外老化监测、微观数值模拟、抗紫外老化剂针对性和抑制紫外老化措施等方面开展进一步研究。