Synergistic Effect of Lithocholic Acid with Gentamicin against Gram-Positive Bacteria but Not against Gram-Negative Bacteria

Listeria monocytogenes (L. monocytogenes) is an important Gram-positive food-borne pathogen that severely threatens public health. A checkerboard microdilution method was performed to evaluate the synergistic effect of lithocholic acid (LCA) with Gentamicin (Genta) against L. monocytogenes. BacLight LIVE/DEAD staining, scanning electron microscopy and biofilm inhibition assays were further used to explore the bactericidal effect and antibiofilm effect of this combination on L. monocytogenes. Additionally, the synergistic effects of LCA derivatives with Genta were also evaluated against L. monocytogenes, S. aureus and S. suis. The results indicated that a synergistic bactericidal effect was observed for the combined therapy of LCA at the concentration without affecting bacteria viability, with Genta. Additionally, LCA in combination with Genta had a synergistic effect against Gram-positive bacteria (L. monocytogenes, S. aureus and S. suis) but not against Gram-negative bacteria (E. coli, A. baumannii and Salmonella). BacLight LIVE/DEAD staining and scanning electron microscopy analysis revealed that the combination of LCA with Genta caused L. monocytogenes membrane injury, leading to bacteria death. We found that 8 μg/mL LCA treatment effectively improved the ability of Genta to eradicate L. monocytogenes biofilms. In addition, we found that chenodeoxycholic acid, as a cholic acid derivative, also improved the bactericidal effect of Genta against Gram-positive bacteria. Our results indicate that LCA represents a broad-spectrum adjuvant with Genta for infection caused by L. monocytogenes and other Gram-positive pathogens.     

Techniques and Algorithms for Hepatic Vessel Skeletonization in Medical Images: A Survey

Hepatic vessel skeletonization serves as an important means of hepatic vascular analysis and vessel segmentation. This paper presents a survey of techniques and algorithms for hepatic vessel skeletonization in medical images. We summarized the latest developments and classical approaches in this field. These methods are classified into five categories according to their methodological characteristics. The overview and brief assessment of each category are provided in the corresponding chapters, respectively. We provide a comprehensive summary among the cited publications, image modalities and datasets from various aspects, which hope to reveal the pros and cons of every method, summarize its achievements and discuss the challenges and future trends.     

Virtual screening of novel noncovalent inhibitors for SARS-CoV 3C-like proteinase

The SARS coronavirus 3C-like proteinase is considered as a potential drug design target for the treatment of severe acute respiratory syndrome (SARS). Owing to the lack of available drugs for the treatment of SARS, the discovery of inhibitors for SARS coronavirus 3C-like proteinase that can potentially be optimized as drugs appears to be highly desirable. We have built a "flexible" three-dimensional model for SARS 3C-like proteinase by homology modeling and multicanonical molecular dynamics method and used the model for virtual screening of chemical databases. After Dock procedures, strategies including pharmocophore model, consensus scoring, and "drug-like" filters were applied in order to accelerate the process and improve the success rate of virtual docking screening hit lists. Forty compounds were purchased and tested by HPLC and colorimetric assay against SARS 3C-like proteinase. Three of them including calmidazolium, a well-known antagonist of calmodulin, were found to inhibit the enzyme with an apparent K(i) from 61 to 178 microM. These active compounds and their binding modes provide useful information for understanding the binding sites and for further selective drug design against SARS and other coronavirus.     

A New Hydroxo‐bridged Chromium(III) Dimer [Cr(saltn)OH]2·4H2O: Synthesis,Crystal Structure and Magnetic Properties

A new hydroxo‐bridged dimeric Cr(III) complex [Cr(saltn)OH]₂·4H₂O [H₂saltn=N,N′‐bis(salicylidene)trimethylenediamine] has been synthesized and its structural and magnetic properties have been investigated. The complex crystallizes in the triclinic space group P‐1 with one dimeric formula unit in a cell of dimensions a=0.95828(19) nm, b=0.95926(19) nm, c=1.0437(2) nm, α=86.77(3)°, β=82.48(3)°, and γ=64.93(3)°. The geometry around each chromium(III) center is six‐coordinate, distorted‐octahedral. The bridging Cr₂O₂ unit is strictly planar, as required by the crystallographic symmetry. The Cr? O? Cr′ bridging angle is 99.94(16)°, and the distance between Cr…Cr′ is 0.3019 nm. The magnetic susceptibility of the complex has been examined in the range of 2‐300 K. By using the spin‐spin coupled model for an S₁=S₂=3/2 dimeric system , the magnetic data were fitted to give the parameters of g=2.01(1), J=‐0.85(2) cm^‐1, and zJ' =0.18(3)cm^‐1, indicating the presence of a weak antiferromagnetic spin‐exchange interaction between the Cr(III) ions in the binuclear complex.     

偏最小二乘法用于同步荧光法同时测定维生素B1,维生素B2和维生素B6

本文将偏最小二乘法结合同步荧光扫描技术对含维生素Ｂ１，Ｂ２和Ｂ６的混合物进行了同时测定。对同步荧光法的测定条件及△λ的选择进行了试验和讨论，比较了△λ分别为６５ｎｍ和３０ｎｍ时的计算结果。所建立的方法用于复合维生素Ｂ片等药片叶Ｂ１，Ｂ２和Ｂ６孤同时测定，获较满意的结果。     

Analysis of Chlorogenic Acid in Herbal Medicines by Capillary Electrophoresis

Atpresent,thecommonlyusedmethodforanalyzingherbalmedicinesishighperformanceliquidchromatography(HPLC).However,theuseofHPLCisrestrictedformanyreasons.Themostseriousproblemisthatthechromatographiccolumniseasilycontaminated.ComparedwithHPLC,capillaryelectrophoresis(CE)ischaracterizedwithhighefficiency,rapidity,lowcostandmultiplemodestobechosen.Inaddition,thecapillarycanbeeasilyregenerated.SoCEisidealforanalyzing"dirty"samples,suchasChineseherbalmedicines.Infact,studiesintheareaarebecoming…     

Meso-四(对-磺基苯基)卟啉光度法测定螺旋藻中的痕量锌

在pH=4．5的乙酸-乙酸钠缓冲介质中，锌和meso-四-（对磺基苯基）卟啉生成1：l的黄色配合物，λmax=421nm，ε=4.34×105L·mol-1·cm-1。该法可不经分离直接测定螺旋藻中的锌,结果满意。     

Pd/SAPO-34催化剂上CO低温氧化反应

 采用水热法合成了小晶粒的 SAPO-34, MnSAPO-34 和 CuSAPO-34 分子筛, 并以它们为载体采用浸渍法制备了一系列不同 Pd 含量的催化剂用于催化 CO 氧化反应. 结果表明: 分子筛载体、催化剂制备条件、反应条件、Pd 含量及预还原等对催化剂的活性影响较大. 催化剂活性随焙烧温度的增加而降低, 而随着反应温度的升高而提高, 担载在 SAPO-34 上 Pd 含量为 1.35% 时性能最佳. X射线衍射和透射电镜结果表明 Pd 物种高度分散于催化剂上, 粒子粒径在 2~8 nm; X射线光电子能谱及氢气程序升温还原结果表明, 高度分散的 Pd2+ 物种是 CO 氧化反应活性位. 随着反应进行被还原为 Pd0 物种, 因而导致催化剂活性下降. H2 预还原处理催化剂致使活性下降的实验结果也支持了这一结论.     

两种水产品中农药多残留分析的样品前处理方法及其在111种农药和相关化学品残留同时检测中的应用

建立了两种针对水产品中农药多残留分析的快速样品前处理方法,并将其应用于111种农药及相关化学品残留检测。在样品前处理方法Ⅰ中,样品经丙酮-乙酸乙酯-正己烷(体积比为1∶1∶1)混合溶剂提取,乙腈转溶;在样品前处理方法Ⅱ中,样品用乙腈-水溶液均质,超声波辅助提取,液-液分配。两种方法所得到的提取液分别用Envi-18柱和PSA柱净化后进行气相色谱-质谱(GC-MS)分析。采用选择离子扫描(SIM)方式,外标法定量。该方法简便、快速,在优化的样品前处理条件和GC-MS分析条件下,方法的检出限(S/N=3)为0.001～0.026 mg/kg;在加标水平为0.25 mg/kg时,采用方法Ⅰ时的回收率为72%～113%,相对标准偏差（RSDs）为3.4%～12.1%;采用方法Ⅱ时的回收率为51%～127%(其中回收率为70%～120%的占94%),RSDs为3.2%～13.8%。