Application of a directed conformational search for generating 3-D coordinates for protein structures from alpha-carbon coordinates.

A directed conformational search algorithm using the program CONGEN (ref. 3), which samples backbone conformers, is described. The search technique uses information from the partially built structures to direct the search process and is tested on the problem of generating a full set of backbone Cartesian coordinates given only alpha-carbon coordinates. The method has been tested on six proteins of known structure, varying in size and classification, and was able to generate the original backbone coordinates with RMSs ranging from 0.30-0.87A for the alpha-carbons and 0.5-0.99A RMSs for the backbone atoms. Cis peptide linkages were also correctly identified. The procedure was also applied to two proteins available with only alpha-carbon coordinates in the Brookhaven Protein Data Bank; thioredoxin (SRX) and triacylglycerol acylhydrolase (TGL). All-atom models are proposed for the backbone of both these proteins. In addition, the technique was applied to randomized coordinates of flavodoxin to assess the effects of irregularities in the data on the final RMS. This study represents the first time a deterministic conformational search was used on such a large scale.     

慢性牙周炎患者血清CGRP、PGE2、CCL20与牙周临床指标和Th17/Treg失衡的相关性分析

摘要 目的：探究慢性牙周炎患者血清降钙素基因相关肽（CGRP）、前列腺素E₂（PGE₂）、CC趋化因子配体20（CCL20）与牙周临床指标和辅助性T淋巴细胞17/调节性T淋巴细胞（Th17/Treg）失衡的相关性。方法：选取2020年5月-2022年5月海南省妇女儿童医学中心收治的91例慢性牙周炎患者,根据其严重程度分为轻度组（39例）、中度组（36例）、重度组（16例）,比较三组血清CGRP、PGE₂、CCL20、牙周临床指标[出血指数（BI）、探诊深度（PD）、附着丧失（AL）、菌斑指数（PLI）]、外周血Th17细胞比例、Treg细胞比例、Th17/Treg比值,采用Pearson相关分析血清CGRP、PGE₂、CCL20与牙周临床指标和Th17/Treg失衡的相关性。结果：与轻度组比较,中度组、重度组血清CGRP、Treg细胞比例显著降低（P＜0.05）,血清PGE₂、CCL20、BI、PD、PLI、AL、Th17细胞比例、Th17/Treg比值显著增高（P＜0.05）;与中度组比较,重度组血清CGRP、Treg细胞比例显著降低（P＜0.05）,血清PGE₂、CCL20、BI、PD、PLI、AL、Th17细胞比例、Th17/Treg比值显著增高（P＜0.05）。相关性结果提示,血清PGE₂、CCL20水平与BI、PD、PLI、AL、Th17细胞比例、Th17/Treg比值呈正相关（P＜0.05）,与Treg细胞比例呈负相关（P＜0.05）;血清CGRP水平与BI、PD、PLI、AL、Th17细胞比例、Th17/Treg比值呈负相关（P＜0.05）,与Treg细胞比例呈正相关（P＜0.05）。结论：慢性牙周炎患者血清CGRP、PGE₂、CCL20水平与疾病严重程度、牙周临床指标及Th17/Treg失衡显著相关,血清CGRP、PGE₂、CCL20可能通过影响Th17/Treg平衡参与慢性牙周炎的发生和发展。     

抗胃酸分泌药物对胃内菌群的影响

收集４０例内镜确诊为胃十二指肠溃疡病人,随机分成两组,分别予泰胃美、奥美拉唑口服;干服药前后分别行胃镜检查,并抽吸胃液行需氧菌、厌氧菌及真菌培养。结果示：胃液细菌量及硝酸盐还原菌量与胃液ｐＨ值呈正相关（ｒ＝０．８０２和０．７,ｐ＜０．０１）,抗胃酸分泌药物尤以奥美拉唑引起胃内菌量增加明显。临床治疗消化性溃疡时,应注意胃内微生态防治。     

Cytotaxonomy and breeding system of the genusBiscutella (Cruciferae)

Chromosome counts were determined for 46 populations ofBiscutella representing 28 taxa. The genus was found to contain diploid taxa with 2n = 12, 16 and 18, tetraploid taxa with 2n = 36 and hexaploid taxa having 2n = 54.B. laevigata L. s. l. consists of diploid and tetraploid populations which are poorly differentiated morphologically. TetraploidB. laevigata s. l. and hexaploidB. variegata Boiss. & Reuter (s. l.) are characterized by chromosomal instability. The variation in chromosome numbers and the occurrence of polyploidy is discussed in relation to the taxonomy of the genus. An investigation of the breeding system showed that most of the annual species were self-compatible and partly inbreeding and most of the perennial species self-incompatible and, therefore, outbreeding, while one annual species,B. cichoriifolia Loisel., showed both systems.     

Synthesis and degradation of proteins during wheat endosperm development

Synthesis of proteins rich in lysine declines progressively with endosperm development and these proteins appear to be degraded preferentially at later stages. The proteolytic enzymes in extracts of endosperms at a late stage of development release considerably more lysine radioactivity from labelled endosperm proteins as compared with the enzymes in endosperms at an early stage.     

结直肠息肉切除术患者肠道微生态失调分析及其与癌变进展的相关性

目的分析结直肠息肉切除术患者肠道微生态失调情况及其与癌变进展的相关性。方法前瞻性选择2015年7月至2016年7月在我院行结直肠息肉切除术的89例患者为研究对象,评价所有研究对象手术前后肠道菌群计数、肠道菌群失调情况,采用单因素和多因素Logistic回归分析结直肠息肉切除术患者癌变的影响因素。结果结直肠息肉患者术后大肠埃希菌计数(10.85±0.50)、粪肠球菌计数(10.12±0.55)显著高于术前(8.34±0.41,7.76±0.37)(均P0.01),结直肠息肉患者术后双歧杆菌计数(2.56±0.68)、乳杆菌计数(2.83±0.71)显著低于术前(5.20±1.06,5.93±0.88)(均P0.01)。结直肠息肉患者术后Ⅰ度菌群失调比例(23.60%)显著低于术前(55.06%)(P0.05),结直肠息肉患者术后Ⅱ、Ⅲ度菌群失调比例(50.56%,25.84%)显著高于术前(34.83%,10.11%)(均P0.05)。随访3年显示89例结直肠息肉切除术患者癌变率为33.71%,性别、病理类型不同的结直肠息肉切除术患者癌变率差异无统计学意义(均P0.05),年龄、遗传史、息肉直径、肠道菌群失调程度不同的结直肠息肉切除术患者癌变率差异具有统计学意义(均P0.05)。年龄、遗传史、肠道菌群失调程度是结直肠息肉切除术患者癌变的影响因素(均P0.05)。结论结直肠息肉切除术患者存在明显肠道微生态失调情况,肠道微生态失调是结直肠息肉切除术患者癌变的危险因素,这对临床防治结直肠息肉切除术患者癌变有重要指导意义。     

砂仁对抗生素所致肠道菌群失调小鼠调节作用的探讨

【摘要】 目的 通过建立抗生素诱导小鼠肠道菌群失调模型,应用PCR-变性梯度凝胶电泳(PCR-DGGE)技术分析小鼠肠道菌群失调前后经服用中药砂仁调理后肠道菌群指纹图谱的变化。方法 选用10只昆明种小鼠,正常培养7 d,适应环境后每天取粪便1次,连续3 d;菌群稳定后按100 mg/kg的头孢拉啶灌胃,每天灌胃2次,连续5 d,每天取粪便1次;上述小鼠随机分为两个组,自然恢复组(饲喂基础饲料)和砂仁处理组,每组5只。3 d后每天取粪便1次,连续3 d,提取细菌总DNA,以16S rRNA基因V3区通用引物扩增,对扩增的PCR产物进行DGGE电泳及指纹图谱分析并切胶测序比对。结果 抗生素处理后小鼠肠道菌群与正常小鼠差异有统计学意义,致病菌增加,砂仁处理组小鼠与正常小鼠的肠道菌群指纹图谱有很大的相似性,但与自然恢复组差异有统计学意义。结论 抗生素可导致小鼠肠道菌群失调,而中药砂仁对肠道菌群失调有明显的恢复作用。     

Probing the effect of nitro groups in nitramine based energetic molecules: a DFT and charge density study

The structure, electron density distribution, energetic and electrostatic properties of simple nitramine based energetic TMA, DMNA, MDA and TNA molecules were determined using density functional theory (B3LYP) with the 6-311G^** and aug-cc-pVDZ basis sets coupled with Bader's theory of atoms in molecules. In the NO₂ group substituted molecules, the N–N bond distance increases with the increase of NO₂ groups, whereas in C–N bonds, this effect is relatively less, and the distances are almost equal. The topological analysis of electron density reveals that the electron density ρ_bcp(r) of C–N and N–N bonds are significantly decreasing with the increase of NO₂ groups in the nitramine molecules. The Laplacian of electron density ▽²ρ_bcp(r) of N–NO₂ bonds [DMNA: ? 16.7 eÅ^? 5, MDA: ? 12.8 eÅ^? 5 and TNA: ? 7.9 eÅ^? 5] of the molecules are relatively less negative, and the values also decrease with the increase of NO₂ groups; this implies that the charge concentration decreases with the increase of NO₂ groups, which leads to weakening the N–N bonds of the molecules. The isosurface of molecular electrostatic potential displays high electronegative regions around the NO₂ groups. The oxygen balance OB₁₀₀ of the molecules increases as the number of NO₂ group increases in the molecules, in which, the TNA molecule having maximum OB₁₀₀ value [+7.89]. The band gap, heat of detonation, bond dissociation energy and charge imbalance are predominantly depends on the number of NO₂ group present in the molecule. The charge imbalance parameter (ν) has been calculated for all molecules, which reveals that TNA is a highly sensitive molecule, the corresponding ν value is 0.047.     

The NAD-Booster Nicotinamide Riboside Potently Stimulates Hematopoiesis through Increased Mitochondrial Clearance

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