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1.
《Research in microbiology》2022,173(3):103901
Infections caused by Klebsiella pneumoniae are often difficult to manage due to the high frequency of multidrug resistance, often conferred by efflux pumps. In this study, we analyzed sequence variations of the major RND family multidrug efflux pump AcrB from 387 assembled K. pneumoniae genomes. We confirm that AcrB is a highly-conserved efflux pump in K. pneumoniae, and identified several variants that were prevalent in clinical isolates. Molecular dynamics analyses on two of these variants (L118M and S966A) suggested conformational changes that may correlate with increased drug efflux capabilities. The L118M change resulted in enhanced protein rigidity while the flexibility of drug binding pockets was stable or increased, and the interactions between the proximal pockets and water molecules were stronger. For S966A, the significantly enlarged proximal pocket suggested higher drug accommodation ability. Consistent with these predictions, the L118M and S966A variants conferred a slightly increased ability to grow in the presence of tetracycline and to survive cefoxitin exposure when overexpressed. In summary, our results suggest that the emergence of enhanced-function AcrB variants may be a potential risk for increased antibiotic resistance in clinical K. pneumoniae isolates.  相似文献   
2.
目的 运用锥形束CT(CBCT)对比安氏Ⅱ类1分类和2分类成人患者与正常牙合成人上颌中切牙根尖区牙槽骨厚度,为正畸牙齿移动提供参考。方法 选取2017年2月至2018年10月就诊于山西医科大学第一医院正畸科的安氏Ⅱ类1分类、安氏Ⅱ类2分类成人患者各20例,另选取个别正常牙合成人20名,每位研究对象均拍摄CBCT。分别测量各分组研究对象的左、右上颌中切牙倾斜度∠U1-SN和∠U1-PP,上颌中切牙根尖区唇侧牙槽骨厚度、舌侧牙槽骨厚度及牙槽骨总厚度,将测量结果进行统计分析。 结果 (1)上颌中切牙根尖区唇侧牙槽骨厚度:安氏Ⅱ类2分类组小于安氏Ⅱ类1分类组和正常牙合牙合组;(2)上颌中切牙根尖区舌侧牙槽骨厚度:安氏Ⅱ类2分类组>正常牙合组>安氏Ⅱ类1分类组;(3)上颌中切牙根尖区牙槽骨总厚度:安氏Ⅱ类1分类组小于安氏Ⅱ类2分类组和正常牙合组;(4)安氏Ⅱ类错牙合,上颌中切牙唇倾度增大,根尖区唇侧牙槽骨厚度增加、舌侧牙槽骨厚度减小、牙槽骨总厚度减小。结论 对于安氏Ⅱ类错牙合患者的治疗,应结合牙槽骨厚度制定最佳矫治方案,以防止出现医源性牙槽骨缺损。  相似文献   
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In eusocial insect colonies, non-reproductive workers often perform different tasks. Tasks of an individual worker are shifted depending on various factors, e.g., age and colony demography. Although a vitellogenin (Vg) gene play regulatory roles in both reproductive and non-reproductive division of labours in a honeybee, it has been shown that the insect Vg underwent multiple gene duplications and sub-functionalisation, especially in apical ant lineages. The regulatory roles of duplicated Vgs were suggested to change evolutionarily among ants, whereas such roles in phylogenetically basal ants remain unclear. Here, we examined the expression patterns of conventional Vg (CVg), Vg-like A, Vg-like B and Vg-like C, as well as Vg receptor, during the task shift in an age-dependent manner and under experimental manipulation of colony demography in a primitive ant Diacamma sp. Expressions of CVg and Vg-like A in a brain were associated with a nursing task. It is suggested that associations of brain expressions of these Vgs with worker tasks were acquired in the basal ant lineage, and that such Vg functions could have sub-functionalised in the derived ant lineage.  相似文献   
5.
《药学学报(英文版)》2020,10(10):1926-1942
Acetylcholine (ACh) regulates inflammation via α7 nicotinic acetylcholine receptor (α7 nAChR). Acetylcholinesterase (AChE), an enzyme hydrolyzing ACh, is expressed in immune cells suggesting non-classical function in inflammatory responses. Here, the expression of PRiMA-linked G4 AChE was identified on the surface of macrophages. In lipopolysaccharide-induced inflammatory processes, AChE was upregulated by the binding of NF-κB onto the ACHE promotor. Conversely, the overexpression of G4 AChE inhibited ACh-suppressed cytokine release and cell migration, which was in contrast to that of applied AChE inhibitors. AChEmt, a DNA construct without enzymatic activity, was adopted to identify the protein role of AChE in immune system. Overexpression of G4 AChEmt induced cell migration and inhibited ACh-suppressed cell migration. The co-localization of α7 nAChR and AChE was found in macrophages, suggesting the potential interaction of α7 nAChR and AChE. Besides, immunoprecipitation showed a close association of α7 nAChR and AChE protein in cell membrane. Hence, the novel function of AChE in macrophage by interacting with α7 nAChR was determined. Together with hydrolysis of ACh, AChE plays a direct role in the regulation of inflammatory response. As such, AChE could serve as a novel target to treat age-related diseases by anti-inflammatory responses.  相似文献   
6.
Monosodium glutamate (MSG) is one of the most widely used flavor enhancers throughout the world. The aim of this study is to investigate the genotoxic potential of MSG by using chromosome aberrations (CAs), sister-chromatid exchanges (SCEs), cytokinesis-blocked micronucleus (CBMN), and random amplified polymorphic DNA-polimerase chain reaction (RAPD-PCR) in cultured human lymphocytes and alkaline comet assays in isolated human lymphocytes, which were incubated with six concentrations (250, 500, 1000, 2000, 4000 and 8000 μg/mL) of MSG. The result of this study indicated that MSG significantly and dose dependently increased the frequencies of CAs, SCE and MN in all treatments and times, compared with control. However, the replication (RI) and nuclear division indices (NDI) were not affected. In this paper, in vitro genotoxic effects of the MSG was also investigated on human peripheral lymphocytes by analysing the RAPD-PCR with arbitrary 10-mer primers. The changes occurring in RAPD profiles after MSG treatment include increase or decrease in band intensity and gain or loss of bands. In the comet assay, this additive caused DNA damage at all concentrations in isolated human lymphocytes after 1-h in vitro exposure. Our results demonstrate that MSG is genotoxic to the human peripheral blood lymphocytes in vitro.  相似文献   
7.
目前电子耳蜗主流的言语处理策略是基于滤波器组的言语处理算法,该算法通过分频带进行信号处理并把参数传递到对应的电极上。电子耳蜗滤波器组的频带划分不是等分的,而是按一定规律进行并且符合人耳听觉特性的,其中,Bark域的频带划分是重要的参考。本研究基于Bark域的电子耳蜗频带划分方法,探讨Bark域频带划分的特性并结合目前的电子耳蜗滤波器组的频带划分进行分析,进而探讨频带划分中的曲线拟合方法,为电子耳蜗滤波器组中的频带划分提供重要的方法和参数。  相似文献   
8.
Tembotrione is a triketone herbicide, usually used for post-emergence weed control in corn. Currently, there is little or no published data on its genotoxicity to human cells either in vitro or in vivo. This study evaluated the impact of acute (4 and 24 h) exposure to low concentrations of tembotrione [corresponding to the acceptable daily intake (0.17 μg/mL), residential exposure level (0.002 μg/mL) and acceptable operator exposure level (0.0012 μg/mL)] on human hepatocellular carcinoma cell line HepG2, using biomarkers of oxidative stress, CCK-8 colorimetric assay for cell viability, alkaline comet assay, and cytokinesis-block micronucleus “cytome” assay. Tembotrione applied at concentrations likely to be encountered in occupational and residential exposures induced cytogenetic outcomes in non-target cells despite non-significant changes in the values of oxidative stress biomarkers. We assume that the observed effects were mainly the consequence of impaired metabolic pathways in HepG2 cells due to the inhibition of the enzyme 4-hydroxyphenyl-pyruvate-dioxygenase by tembotrione, which possibly caused a depletion of folate levels leading to excess formation of nuclear buds in the affected cells. Regardless of the fact that tembotrione was previously reported negative for mutations and chromosome aberrations in vitro, our findings call for more precaution in its use.  相似文献   
9.
目的:分析比较微型种植体支抗与口外弓支抗对安氏Ⅱ类1分类错牙合畸形患者的矫治效果。方法:收集笔者医院95例安氏Ⅱ类1分类错牙合畸形患者临床资料,根据其治疗方法将之分为口外弓支抗(MIA组)46例和微型种植体支抗组(HGA组)49例,比较其矫正前后头影测量结果和模型测量结果,矫治时间和不良反应。结果:治疗后,MIA组牙合平面与SN平面夹角(OP-SN)、上颌中切牙牙长轴与SN平面夹角(U1-SN)、上唇突度、下唇突度、上唇最凸点至E线垂直距离(E line-UL)、下唇最凸点至E线垂直距离(E line-LL)、覆牙合(OB)、覆盖(OJ)均小于HGA组(P<0.05),矫治时间短于HGA组(P<0.05),总不良反应发生率与HGA组差异无统计学意义(P>0.05)。结论:对比HGA,MIA对安氏Ⅱ类1分类错牙合畸形患者的矫治效果更佳,且能够缩短矫治时间。  相似文献   
10.
通过采集腿部肌肉5个通道的肌音信号,利用3层决策树对跑步、上楼、下楼、走路、静止5种步态动作进行模式识别研究。在决策树的第1层和第2层,应用双阈值门限法识别静止和跑步两种步态模式,在第3层,提出基于步态信号的自适应不等长分割算法以及改进的模糊熵算法,利用线性分类器对走路、上楼、下楼进行分类识别。结果表明:双门限阈值法可有效地对静止和跑步进行识别,当采用改进的模糊熵特征时,对走路、上楼、下楼3种步态模式的分类准确率达到了94.87%;而当综合利用近似熵、样本熵和改进的模糊熵3种特征时,其分类准确率达到了98.76%。  相似文献   
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