Discovery, structure and function of plasmid mediated shufflon / 生物工程学报

Antimicrobial resistance has become a major public health issue of global concern. Conjugation is an important way for fast spreading drug-resistant plasmids, during which the type Ⅳ pili plays an important role. Type Ⅳ pili can adhere on the surfaces of host cell and other medium, facilitating formation of bacterial biofilms, bacterial aggregations and microcolonies, and is also a critical factor in liquid conjugation. PilV is an adhesin-type protein found on the tip of type Ⅳ pili encoded by plasmid R64, and can recognize the lipopolysaccharid (LPS) molecules that locate on bacterial membrane. The shufflon is a clustered inversion region that diversifies the PilV protein, which consequently affects the recipient recognition and conjugation frequency in liquid mating. The shufflon was firstly discovered on an IncI1 plasmid R64 and has been identified subsequently in plasmids IncI2, IncK and IncZ, as well as the pathogenicity island of Salmonella typhi. The shufflon consists of four segments including A, B, C, and D, and a specific recombination site named sfx. The shufflon is regulated by its downstream-located recombinase-encoding gene rci, and different rearrangements of the shufflon region in different plasmids were observed. Mobile colistin resistance gene mcr-1, which has attracted substantial attentions recently, is mainly located in IncI2 plasmid. The shufflon may be one of the contributors to fast spread of mcr-1. Herein, we reviewed the discovery, structure, function and prevalence of plasmid mediated shufflon, aiming to provide a theoretical basis on transmission mechanism and control strategy of drug-resistant plasmids.

Synergistic effect of β-thujaplicin and tigecycline against tet(X4)-positive Escherichia coli in vitro / 生物工程学报

The widespread of tigecycline resistance gene tet(X4) has a serious impact on the clinical efficacy of tigecycline. The development of effective antibiotic adjuvants to combat the looming tigecycline resistance is needed. The synergistic activity between the natural compound β-thujaplicin and tigecycline in vitro was determined by the checkerboard broth microdilution assay and time-dependent killing curve. The mechanism underlining the synergistic effect between β-thujaplicin and tigecycline against tet(X4)-positive Escherichia coli was investigated by determining cell membrane permeability, bacterial intracellular reactive oxygen species (ROS) content, iron content, and tigecycline content. β-thujaplicin exhibited potentiation effect on tigecycline against tet(X4)-positive E. coli in vitro, and presented no significant hemolysis and cytotoxicity within the range of antibacterial concentrations. Mechanistic studies demonstrated that β-thujaplicin significantly increased the permeability of bacterial cell membranes, chelated bacterial intracellular iron, disrupted the iron homeostasis and significantly increased intracellular ROS level. The synergistic effect of β-thujaplicin and tigecycline was identified to be related to interfere with bacterial iron metabolism and facilitate bacterial cell membrane permeability. Our studies provided theoretical and practical data for the application of combined β-thujaplicin with tigecycline in the treatment of tet(X4)-positive E. coli infection.

Application of whole genome sequencing technology and bioinformatics analysis in antimicrobial resistance researches / 生物工程学报

The emergence and spread of antimicrobial resistance has become a serious global issue. Bacterial characteristics, such as antimicrobial resistance genes, virulence-associated genes, plasmid types, and phylogenetic relationship among different strains, are the keys to unravel the occurrence and dissemination of antimicrobial resistance. However, the accuracy and efficiency of the traditional techniques, such as polymerase chain reaction and pulsed field gel electrophoresis is insufficient to underlying the mystery of antimicrobial resistance. Recently, the whole genome sequencing and high-throughput bioinformatics analysis have been successfully used in antimicrobial resistance studies, helping scientists to obtain the nature of antimicrobial resistance bacteria quickly, and more precisely to paint the evolutionary relationship among different strains. Therefore, in this study, we aim to systematically introduce the recent development of whole genome sequencing analysis, including different methods and corresponding characteristics of library preparation, platform sequencing, data analysis, and the latest application of the technology in the antimicrobial resistance research. We hope that this review can provide more comprehensive knowledge about whole genome sequencing and bioinformatic analysis for antimicrobial resistance research.

Analysis of human genetic resources project application for examination and approval / 中华医学科研管理杂志

Objective To summarize the characteristic of projects accepted by human genetic resources management office in 2016 and put forward further measures.Methods Statistic analyses were carried out based on the overall projects application,then Chinese application units and partners were analyzed separately.Results 1 138 international cooperation projects were approved in total,mainly on clinical research.24 countries were involved with increasing trend of globalization.Conclusions The human genetic resources management played a positive role in the development of the biomedical research and industry.

Electrochemical Immunosensor for Determination of Microcystins Based on Carbon Nanotubes/Au Nanoparticles Composite Film / 分析化学

Carbon nanotubes/Au nanoparticles ( CNT/AuNP ) composite film was fabricated on glassy carbon electrode ( GCE) by first dropping CNTs on the electrode surface and then electrodeposition of AuNPs by multi-potential step. The antibody of microcystin-( leucine-arginine ) ( anti-MCLR ) was immobilized on the modified electrode surface through adsorption on AuNPs. Subsequently, bovine serum albumin ( BSA) was used to block the non-specific adsorption to obtain the immunosensor for MCLR assay. The immunosensor could effectively capture MCLR by the specific immunoreaction between the electrode surface-confined antibody and MCLR, followed by the attachment of the anti-MCLR HRP-labeled to form a sandwich-type system. The analysis of MCLR was performed based on the catalytic reaction of HRP toward the oxidation of hydroquinone ( QH2 ) by H2 O2 . Under the optimal experimental conditions, the peak current response increased linearly with the concentration of MCLR in the range of 0 . 50-12 μg/L with a detection limit of 0. 30 μg/L (S/N=3). The developed immunosensor was used to determine MCLR in real water samples, and the recoveries of standard addition experiments were in the range of 93 . 0%-108 . 5%, with the relative standard deviation of 3 . 8%-5 . 0%.

Ultra Performance Liquid Chromatography-Tandem Mass Spectrometric Method for Determination of Coccidiostats in Chicken Skin and Fat / 分析化学

A method based on ultra performance liquid chromatography-tandem mass spectrometry ( UPLC-MS/MS) has been proposed for the determination of coccidiostat residues in chicken skin and fat. The sample was extracted with the combination of methanol, acetonitrile, and acetic acid, and cleaned-up by Sep-Pak tC18 solid phase extraction cartridge. Data acquisition under positive electrospray mode was performed by applying multiple reaction monitoring for both identification and quantification. The limits of detection and quantification for halofuginone and robenidine were 7 μg/kg and 20 μg/kg, respectively. The limit of detection of salinomycin, monensin, narasin, maduramicin, and lasalocid was 5 μg/kg, and limit of quantification was 15 μg/kg. The recovery was 75% to 110% in the spiked concentration range from 15 μg/kg to 200 μg/kg, with intra-day precision lower than 12. 8%, and inter-day precision lower than 13 . 4%.

The changes in vestibular function in patients with diabetes mellitus and its clinical significance / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To study the changes of vestibular function in patients with diabetes mellitus and its clinical significance.@*METHOD@#Electronystagmography (ENG) was used to examine 76 patients with diabetes mellitus and 60 healthy adults subjects. After clinical detection of vestibular function including spontaneous nystagmus, positional test, head shaking nystagmus, neck torsion test, caloric test, and sensory organization tests which consist of gaze, saccade and smooth pursuit test, the results of these two groups were recorded for qualitative and quantitative statistical analysis.@*RESULT@#The rate of vestibular dysfunction in patients with diabetes mellitus were 68.4%. and that of the controls were 8.3%. There was significant difference between these two groups (chi2 = 15.472, P < 0.01).@*CONCLUSION@#Vertigo or dizziness occurred in patients with diabetes mellitus might be related to vestibular dysfunction. ENG test could be used as one of the objective clinical examinations in patients with diabetes mellitus.

Application of auditory brainstem response and distortion product otoacoustic emission in the clinical detection of hearing loss in patients with diabetes mellitus / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To study the characteristic of hearing loss and the changes of the auditory brainstem response and distortion product otoacoustic emission in diabetics.@*METHOD@#General information of 136 diabetics were investigated whether had the complication of capillary vessel and hearing loss with self-made questionnaire at random. 136 cases (272 ears) were tested with ABR and DPOAE. They were divided into A, B, C, D four groups according to the age of per ten years (30-70 years). Other 120 (240 ears) matched healthy adult were enrolled in the control group. The pure tone threshold (PTT), acoustic impedance, ABR and DPOAE results were compared between the four groups and the control group, and then made statistical analysis.@*RESULT@#When comparing to the control group, the interpeak latency I-V and ABR response were no significant difference between patients at the stage of 30 years. Not only the threshold of wave V was elevated with aging in patients over 40 years, but the amplitude of the peak latencies of waves III and V were lessening, and the interpeak latency III-V and I-V were prolonged between patients at the stage of 60 years, which had significant difference compared with age-matched patients (P < 0.05). The inducing rate of DPOAE were 100% in the test and control group, but the amplitude of DPOAE declined ranged from 1 to 8 kHz in patients with early diabetes mellitus and were significantly reduced at 4 kHz, which had significant difference compared with age-matched patients (P < 0.05).@*CONCLUSION@#The majority of patients with diabetes mellitus had slight and moderate hearing loss gradually. The ABR and the threshold of ABR response were varied with the age and sex of patients, and whether had the complication of capillary vessel, but were not related to its type and disease course. The DPOAE can comprehend the cochlear disorder in patients with early diabetes mellitus.

The study of expression of the basic fibroblast growth factor in normal and degenerated human intervertebral disc / 中华骨科杂志

Objective To investigate the expression of the basic fibroblast growth factor (bFGF) in normal and degenerated human intervertebral discs in order to determine whether bFGF is related to degeneration of the intervertebral disc. Methods The specimens of the intervertebral discs from 11 male and 19 female patients undergone lumbar disc herniation surgery (observation group) and 6 patients with scoliosis following anterior release (control group) were harvested. The tissues were histologically observed to confirm their degenerated or normal status and then conducted for the expression of bFGF and its mRNA with immunohistochemistry and in situ hybridization. Results In the observation group, all the samples were found to be degenerated disc tissue, and the positive rate of the expression of bFGF was 90% (27/30) with immunohistochemistry and 20% (6/30) with in situ hybridization. In the control group, all the samples were shown to be normal disc tissues, and had negative expression of bFGF with immunohistochemistry and in situ hybridization. The positive rate of the expression of bFGF showed significant difference between the two groups. Conclusion The expression of bFGF showed significant difference between the degenerated and normal intervertebral discs, which indicated that the bFGF might promote proliferation of chondrocyte and synthesis of extracellular matrix in the degenerated discs as a proliferation stimulating factor.

Study on the disinfection efficacy of compound disinfectant of peracetic acid / 中华疾病控制杂志

Objective To study the disinfection efficacy of c ompound disinfectant of peracetic acid. Methods Suspended liqu id quantitative sterilization test and metal corrosion test were carried out wit h different concentrations of disinfectant compound. Results T he killing rate of Bacillus subtilis var.niger spores e xposed to peracetic acid 500 mg*L-1 or available chlorine 300 mg*L-1 for 15 minutes was 99.94% and 97.91% respectively, while that of the spores e xpos ed to the compound disinfectant containing both of them reached 100%. The influ ence of organic substances on the bactericidal efficacy of this compound disinfe ctant was less than that on the bactericidal efficacy of the single ingredient. The corrosive effect of the compound disinfectant on the metals was milder than that of peracetic acid, but heavier than that of dichlorodimethylhydantoin. Conclusions Disinfectant efficacy of compound disinfectant increase s clearly, while metal corrosiveness decreases.