叶绿素荧光成像技术的葡萄霜霉病早期检测

葡萄霜霉病对葡萄生产构成严重威胁,尽早防治是治理霜霉病的关键.为了对该病进行早期检测,以PCR检测获取的霜霉病相对生物量作为霜霉病侵染的依据,从暗适应—光适应—暗弛豫3个光合生理状态连续变化过程中,采集80个人工接种霜霉菌叶片和80个健康对照叶片连续6 d的叶绿素荧光图像.对比健康和接种叶片叶绿素荧光动力学曲线、参数图...     

硒与HIV感染的关系研究进展

HIV感染及AIDS至今依然严重威胁着人类的生命,因而成为医学界研究的热点。本文着重从硒与细胞因子角度揭示硒与HIV和AIDS在发生、发展中的关系,证明其扮演的重要角色,提示了一种研究HIV和AIDS的新方向。     

Conversion of biomass to ethanol

In theEscherichia coli cell-free system, the modification of cell extract can be achieved by preparation of the strains carrying additional property or those being induced with a certain gene expression prior to harvesting. In this study, we analyzed the cell-free system with S30 extract containing T7 RNA polymerases (S30 extract-T7pol) prepared from E.coli BL21(DE3) strain, which includes T7 RNA polymerase from extrinsic genes by IPTG induction, as a model for the improvement of the cell-free system. The fact that a significant degree of mRNA degradation was observed in the cell-free system with S30 extract-T7pol indicates the increase of ribonuclease activity was an unfavorable influence derived from the cell-extract modification process. We also showed that this influence was settled by the addition of an effective ribonuclease inhibitor, such as copper (II) ion, to the reaction mixture.     

Determination of vancomycin and meropenem in serum and synovial fluid of patients with prosthetic joint infections using UPLC–MS/MS

Numerous studies have suggested that intra-articular administration of antibiotics following primary revision surgery may be one of the methods for treating prosthetic joint infection (PJI). Vancomycin and meropenem are the two most commonly used antibiotics for local application. Determining the concentrations of vancomycin and meropenem in the serum and synovial fluid of patients with PJI plays a significant role in further optimizing local medication schemes and effectively eradicating biofilm infections. This study aimed to establish a rapid, sensitive, and accurate ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method for determining the concentrations of vancomycin and meropenem in human serum and synovial fluid. Serum samples were processed using acetonitrile precipitation of proteins and dichloromethane extraction, while synovial fluid samples were diluted before analysis. Chromatographic separation was achieved in 6 min on a Waters Acquity UPLC BEH C18 column, with the mobile phase consisting of 0.1% formic acid in water (solvent A) and acetonitrile (solvent B). Quantification was carried out using a Waters XEVO TQD triple quadrupole mass spectrometer with an electrospray ionization (ESI) source in positive ion mode. The multiple reaction monitoring (MRM) mode was employed to detect the following quantifier ion transitions: 717.95–99.97 (norvancomycin), 725.90–100.04 (vancomycin), 384.16–67.99 (meropenem). The method validation conformed to the guidelines of the FDA and the Chinese Pharmacopoeia. The method demonstrated good linearity within the range of 0.5–50 μg/ml for serum and 0.5–100 μg/ml for synovial fluid. Selectivity, intra-day and inter-day precision and accuracy, extraction recovery, matrix effect, and stability validation results all met the required standards. This method has been successfully applied in the pharmacokinetic/pharmacodynamic (PK/PD) studies of patients with PJI.     

The effects of immunity and resistance on the development of AIDS

We incorporate basic genetics into an AIDS model. We illustrate that if a homozygote is immune to the disease or is resistant to the effects of the disease, the corresponding allele goes to fixation. On the other hand, if the heterozygote is immune to the disease or is resistant to the effects of the disease, polymorphism usually occurs.     

A CLASS OF SIS EPIDEMIC MODEL WITH SATURATION INCIDENCE AND AGE OF INFECTION

Saturating contact rate of individual contacts is crucial in an epidemiology model.A mathematical SIR model with saturation incidence and age of infec- tion is formulated in this paper.In addition,we study the dynamical behavior of this model and define the basic reproductive number R_0.The authors also prove that the diseased-free equilibrium is globally asymptotically stable if R_0<1. The endemic equilibrium is locally asymptotically stable if K_1>αand R_0>1.     

儿童反复呼吸道感染与发锌、铁、铜、钙关系分析

为了解反复呼吸道感染与头发微量元素的关系,测定了52例易感儿及41例健康儿童发锌,铁,铜,钙含量,结果显示,易感儿发锌含量极显著低于健康组（P＜0．01）,发钙偏低,0．05＞P＞0．01,发铁,铅含 量基本正常,两组无显著差异,本研究表明儿童反复呼吸道感染与缺锌,缺钙有关。     

Combating multidrug resistance in bacterial infection by targeting functional proteome with natural products

Antibiotic resistance has become a major clinical and public health problem within the lifetime of most people living today. Development of new therapeutic approaches to prevent antimicrobial chemotherapy from bacterial multidrug resistance has thus been becoming a primary consideration in the medicinal community. In this study, we describe a protocol that is potential for combating multidrug resistance by rational screening of natural medicines to target the bacterial functional proteome. To achieve this, a pipeline of integrating virtual screening and susceptibility testing has been described to identify antibacterial agents from various natural products with diverse structures and high drug-likeness. A number of promising candidates with potent antibacterial activity were identified, from which six available compounds were assayed to determine their susceptibility to four multidrug-resistant strains. Consequently, while most tested candidates showed moderate (20 < MIC < 50 μg/mL) or low (MIC>50 μg/mL) antibacterial activities, two natural products, i.e. pseudopterosin A and ciprofloxacin, were measured to possess strong broad-spectrum potency combating different strains (MIC < 20 μg/mL).     

Biocatalytic reduction of prochiral aromatic ketones to optically pure alcohols by a coupled enzyme system for cofactor regeneration

A simple, highly efficient, and economical biphasic cell-free system was developed for biocatalytic reduction of prochiral aromatic ketones to furnish enantiopure alcohols. This system is characterized by using endogenous enzymes of the cell-free extract to form enzyme-coupled NADPH recycling system. Besides, it offered much higher productivity than whole cells and greatly simplified the preparation process of biocatalysts in comparison with isolated enzymes. Various prochiral aromatic ketones, especially α-substituted acetophenone derivatives, were reduced to chiral alcohols with excellent enantiomeric excess (ee) and moderate to good yield by this cell-free system.