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991.
Shengjuan Hu Yan Zhou Yanhong Deng Yang Bo Xianmei Chen Wei Yang Ruichun Shi Wei Zhao Zhanbing Hou Jianping Hu Jianguo Liu Xilong Zhang Heli Yong Ping Wang Fei Li Hailong Qi Xiaoyun Wang Lijuan Jin Ting Cui Haijiang Yong Xue Li Bin Yang Yuehua Yu Bin Ma Lei Fu Xuemei Wang Zhen Ma Na Tang Yanjie You Jianyang Guo Xiaobing Yu Li Yao Ruiping Gao Yanling Li Ruijuan Xin Jianfang Liu Zhenzi Cao Hongliang Li Linke Ma Shoucheng Ma Ying Cao Yuanyuan Tang Jun Liu Qian Hao Xiaofei Li Xuemei Li Rui Mu Min Niu Xiaoming Su Hengjun Gao 《Helicobacter》2023,28(3):e12960
Background
Geographic differences exist in the antibiotic resistance patterns of Helicobacter pylori. Personalized treatment regimens based on local or individual resistance data are essential. We evaluated the current status of H. pylori resistance in Ningxia, analyzed resistance-related factors, and assessed the concordance of phenotypic and genotypic resistance.Methods
Strains were isolated from the gastric mucosa of patients infected with H. pylori in Ningxia and relevant clinical information was collected. Phenotypic antibiotic susceptibility assays (Kirby–Bauer disk diffusion) and antibiotic resistance gene detection (Sanger sequencing) were performed.Results
We isolated 1955 H. pylori strains. The resistance rates of H. pylori to amoxicillin, levofloxacin, clarithromycin, and metronidazole were 0.9%, 42.4%, 40.4%, and 94.2%, respectively. Only five tetracycline-resistant and one furazolidone-resistant strain were identified. Overall, 3.3% of the strains were sensitive to all six antibiotics. Multidrug-resistant strains accounted for 22.9%, of which less than 20% were from Wuzhong. Strains isolated from women and patients with nonulcerative disease had higher rates of resistance to levofloxacin and clarithromycin. Higher rates of resistance to metronidazole, levofloxacin, and clarithromycin were observed in the older age group than in the younger age group. The kappa coefficients of phenotypic resistance and genotypic resistance for levofloxacin and clarithromycin were 0.830 and 0.809, respectively, whereas the remaining antibiotics showed poor agreement.Conclusion
H. pylori antibiotic resistance is severe in Ningxia. Therefore, furazolidone, amoxicillin, and tetracycline are better choices for the empirical therapy of H. pylori infection in this region. Host sex, age, and the presence of ulcerative diseases may affect antibiotic resistance of the bacteria. Personalized therapy based on genetic testing for levofloxacin and clarithromycin resistance may be a future direction for the eradication therapy of H. pylori infection in Ningxia. 相似文献992.
Weigen Huang Yakov Kuzyakov Shuli Niu Yu Luo Bo Sun Jiabao Zhang Yuting Liang 《Global Change Biology》2023,29(22):6188-6200
Plant- and microbially derived carbon (C) are the two major sources of soil organic matter (SOM), and their ratio impacts SOM composition, accumulation, stability, and turnover. The contributions of and the key factors defining the plant and microbial C in SOM along the soil profile are not well known. By leveraging nuclear magnetic resonance spectroscopy and biomarker analysis, we analyzed the plant and microbial C in three soil types using regional-scale sampling and combined these results with a meta-analysis. Topsoil (0–40 cm) was rich in carbohydrates and lignin (38%–50%), whereas subsoil (40–100 cm) contained more proteins and lipids (26%–60%). The proportion of plant C increases, while microbial C decreases with SOM content. The decrease rate of the ratio of the microbially derived C to plant-derived C (CM:P) with SOM content was 23%–30% faster in the topsoil than in the subsoil in the regional study and meta-analysis. The topsoil had high potential to stabilize plant-derived C through intensive microbial transformations and microbial necromass formation. Plant C input and mean annual soil temperature were the main factors defining CM:P in topsoil, whereas the fungi-to-bacteria ratio and clay content were the main factors influencing subsoil CM:P. Combining a regional study and meta-analysis, we highlighted the contribution of plant litter to microbial necromass to organic matter up to 1-m soil depth and elucidated the main factors regulating their long-term preservation. 相似文献
993.
Minghui Niu Heng Zhang Xiangyang Li Zhibao Hu Hongjiao Zhang Zhiru Xu Chunpu Qu Guanjun Liu 《Phyton》2023,92(7):2001-2015
KANADI (KAN) is a plant-specific gene that controlled the polarity development of lateral organs. It mainly acted on the abaxial characteristics of plants to make the lateral organs asymmetrical. However, it had been less identified in woody plants. In this study, the members of the KAN gene family in Populus trichocarpa were identified and analyzed using the bioinformatics method. The results showed that a total of 8 KAN family members were screened out, and each member contained the unique GARP domain and conserved region of the family proteins. Phylogenetic analysis and their gene structures revealed that all KAN genes from P. trichocarpa, Arabidopsis thaliana, and Nicotiana benthamiana could be divided into four subgroups, while the eight genes in P. trichocarpa were classified into three subgroups, respectively. The analysis of tissue-specific expression indicated that PtKAN1 was highly expressed in young leaves, PtKAN6 was highly expressed in young leaves and mature leaves, PtKAN2, PtKAN5, and PtKAN7 were highly expressed in nodes and internodes, PtKAN8 was highly expressed in roots, and PtKAN3 and PtKAN4 showed low expression levels in all tissues. Among them, PtKAN2 and PtKAN6, and PtKAN4 and PtKAN5 might have functional redundancy. Under high nitrogen concentrations, PtKAN2 and PtKAN8 were highly expressed in mature stems and leaves, respectively, while PtKAN4, PtKAN5, and PtKAN7 were highly expressed in roots. This study laid a theoretical foundation for further study of the KAN gene-mediated nitrogen effect on root development. 相似文献
994.
Lingyan Zhou Tao Guo Lanxia Meng Xingyu Zhang Ye Tian Lijun Dai Xuan Niu Yiming Li Congcong Liu Guiqin Chen Chaoyang Liu Wei Ke Zhaohui Zhang Anyu Bao Zhentao Zhang 《Aging cell》2023,22(3):e13745
The aggregation of α-synuclein plays a pivotal role in the pathogenesis of Parkinson's disease (PD). Epidemiological evidence indicates that high level of homocysteine (Hcy) is associated with an increased risk of PD. However, the molecular mechanisms remain elusive. Here, we report that homocysteine thiolactone (HTL), a reactive thioester of Hcy, covalently modifies α-synuclein on the K80 residue. The levels of α-synuclein K80Hcy in the brain are increased in an age-dependent manner in the TgA53T mice, correlating with elevated levels of Hcy and HTL in the brain during aging. The N-homocysteinylation of α-synuclein stimulates its aggregation and forms fibrils with enhanced seeding activity and neurotoxicity. Intrastriatal injection of homocysteinylated α-synuclein fibrils induces more severe α-synuclein pathology and motor deficits when compared with unmodified α-synuclein fibrils. Increasing the levels of Hcy aggravates α-synuclein neuropathology in a mouse model of PD. In contrast, blocking the N-homocysteinylation of α-synuclein ameliorates α-synuclein pathology and degeneration of dopaminergic neurons. These findings suggest that the covalent modification of α-synuclein by HTL promotes its aggregation. Targeting the N-homocysteinylation of α-synuclein could be a novel therapeutic strategy against PD. 相似文献
995.
Tzong-Bor Sun Kuo-Feng Huang Ko-Chi Niu Cheng-Hsien Lin Wen-Pin Liu Chao-Hung Yeh Shu-Chun Kuo Ching-Ping Chang 《Journal of cellular and molecular medicine》2023,27(20):3189-3201
Retinal ischemia followed by reperfusion (IR) is a common cause of many ocular disorders, such as age-related macular degeneration (AMD), which leads to blindness in the elderly population, and proper therapies remain unavailable. Retinal pigment epithelial (RPE) cell death is a hallmark of AMD. Hyperbaric oxygen (HBO) therapy can improve IR tissue survival by inducing ischemic preconditioning responses. We conducted an in vitro study to examine the effects of HBO preconditioning on oxygen–glucose deprivation (OGD)-induced IR-injured RPE cells. RPE cells were treated with HBO (100% O2 at 3 atmospheres absolute for 90 min) once a day for three consecutive days before retinal IR onset. Compared with normal cells, the IR-injured RPE cells had lower cell viability, lower peroxisome proliferator activator receptor-alpha (PPAR-α) expression, more severe oxidation status, higher blood-retinal barrier disruption and more elevated apoptosis and autophagy rates. HBO preconditioning increased PPAR-α expression, improved cell viability, decreased oxidative stress, blood-retinal barrier disruption and cellular apoptosis and autophagy. A specific PPAR-α antagonist, GW6471, antagonized all the protective effects of HBO preconditioning in IR-injured RPE cells. Combining these observations, HBO therapy can reverse OGD-induced RPE cell injury by activating PPAR-α signalling. 相似文献
996.
997.
用崔道珊等构建的噬菌体T7溶菌酶工程菌株,培养物经超声破碎和DE52,CM52柱层析纯化,我们得到电泳纯的T7溶菌酶,分子量为17000,最适反应pH为8.0.其热稳定性欠佳,保温37℃,5min即丧失酶活21%. 相似文献
998.
Ni^2+对心肌细胞Na^+,K^+活度及膜钠泵活动的影响 总被引:5,自引:0,他引:5
本实验应用离子选择性微电极方法,动态监测了Ni2+对心肌细胞Na+、K+活度的影响,并以细胞内Na+逐出速率[d(aiNa)/dt]作为膜钠泵活动度的指标,观察了Ni2+对膜钠泵活动的影响。结果显示:(1)在本实验浓度下Ni2+对静息及活动(自律或电刺激)的细胞内Na+、K+活度无明显影响;(2)可使细胞外K+活度升高;(3)便刺激停止即刻细胞内Na+逐出速率下降;(4)减小无钠无钙液引起的细胞外K+活度下降幅度。结果提示:Ni2+对处于高水平活动的心肌细胞膜钠泵具有明显的抑制作用,而对处于一般活动状态的膜钠泵则未见有明显影响;在Ni2+存在下心肌细胞膜对K+的通透性有不同程度的提高。 相似文献
999.
Guodong Shao Guntars O. Martinson Marife D. Corre Jie Luo Dan Niu Xenia Bischel Edzo Veldkamp 《Global Change Biology Bioenergy》2023,15(1):58-71
Monoculture croplands are a major source of global anthropogenic emissions of nitrous oxide (N2O), a potent greenhouse gas that contributes to ozone depletion. Agroforestry has the potential to reduce N2O emissions. Presently, there is no systematic comparison of soil N2O emissions between cropland agroforestry and monoculture systems in Central Europe. We investigated the effects of converting the monoculture cropland system into the alley cropping agroforestry system on soil N2O fluxes at three sites (each site has paired agroforestry and monoculture) in Germany, where agroforestry combined crop rows and poplar short-rotation coppice (SRC). We measured soil N2O fluxes monthly over 2 years (March 2018–January 2020) using static vented chambers. Annual soil N2O emissions from agroforestry ranged from 0.21 to 2.73 kg N ha−1 year−1, whereas monoculture N2O emissions ranged from 0.34 to 3.00 kg N ha−1 year−1. During the rotation of corn crop, with high fertilization rates, agroforestry reduced soil N2O emissions by 9% to 56% compared to monocultures. This was mainly caused by low soil N2O emissions from the unfertilized agroforestry tree rows. Soil N2O fluxes were predominantly controlled by soil mineral N in both agroforestry and monoculture systems. Our findings suggest that optimized fertilizer input will further enhance the potential of agroforestry for mitigating N2O emissions. 相似文献
1000.
13C spin-lattice relaxation times (T1's) of four cyclic hexapeptides of sequence, (X-L -Pro-Y)2, are reported. The T1's of the protonated carbons, which undergo dipolar relaxation, are interpreted qualitatively in terms of the overall tumbling motion of the molecule and in terms of internal motion. It is found that three of the cyclic hexapeptides, those which adopt all-trans β-conformers, tumble isotropically and appear to lack internal motion in the peptide backbone. The method of Torchia and Lyerla was applied to these compounds in order to compare the mobility of the proline rings. The results show that the sequence and particular type of β-turn present affect the internal motion of the Pro ring. Data on a fourth cyclic hexapeptide, which occurs in a conformation with two-cis X-Pro bonds, suggests that internal motion of the backbone contributes an additional frequency component to the motion of the Y residue α-carbons. A consideration of the mobility of the proline rings in the conformer with two-cis peptide bonds revealed that they are significantly more rigid in the two-cis structure than in the all-trans. 相似文献