结肠手术后肠道细菌易位早期诊断的研究

目的研究结肠手术后与细菌易位的主要相关因素。方法选择广东医学院附属医院胃肠外科2005年2月～2006年3月期间收治的结肠癌行手术的患者42例,选取尿中乳果糖/甘露醇浓度(L/M)比值、白介素-6(IL-6)、APCHEⅡ评分、白细胞计数(WBC)、手术方式等指标与细菌易位行单因素和多因素Logistic回归分析。结果单因素分析结果显示,细菌易位阳性患者尿中L/M比值、APACHEⅡ评分、IL-6、WBC计数与阴性患者均有显著意义。多因素分析结果显示细菌易位只与APACHEII评分、WBC计数、IL-6有稳定关系。结论在估计细菌易位可能性大小时,除了了解与其相关的因素外,应重视细菌易位有关的稳定因素。     

结肠手术后肠道细菌易位早期诊断的研究

目的研究结肠手术后与细菌易位的主要相关因素.方法选择广东医学院附属医院胃肠外科2005年2月～2006年3月期间收治的结肠癌行手术的患者42例,选取尿中乳果糖/甘露醇浓度(L/M)比值、白介素-6 (IL-6)、APCHEⅡ评分、白细胞计数(WBC)、手术方式等指标与细菌易位行单因素和多因素Logistic回归分析.结果单因素分析结果显示,细菌易位阳性患者尿中L/M比值、APACHEⅡ评分、IL-6、WBC计数与阴性患者均有显著意义.多因素分析结果显示细菌易位只与APACHEⅡ评分、WBC计数、IL-6有稳定关系.结论在估计细菌易位可能性大小时,除了了解与其相关的因素外,应重视细菌易位有关的稳定因素.     

结肠气钡造影对先天性巨结肠的诊断价值

结肠气钡双重造影检查诊断先天性巨结肠是不可缺少的直接观察的一种方法,指导治疗具有重要意义;对于28例经手术病理证实为先天性巨结肠的患者接受了普通X线结肠气钡双重造影检查,其中男19例、女9例,15例显示狭窄段以上扩张、13例显示痉挛段与扩张段成漏斗状;所有检查的结肠病变肠管的肠壁和粘膜下神经丛内的缺乏神经细胞而处于痉挛状态,丧失了正常的肠蠕动和排泄功能,粪便、肠气蓄积在远端结肠,使该段肠管继发扩张、肥厚、逐步形成巨结肠的改变。由于出现肠扭转及肠梗阻,所以,早期诊断是非常重要的。从1997～2009年收集经过结肠气钡双重造影检查诊断先天性巨结肠的28例患者,做一以下总结。     

相关和回归分析的关系及其预测价值研究

相关和回归分析在统计工作中发挥着重要的作用,分清其区别和联系对于统计的准确性有很大的影响,本文从两者的概念入手,指出两者的区别和联系,并对其在统计中的作用和价值进行了分析.     

云南省高血压患病率影响因素的类回归分析

分析影响高血压的患病率因素,对高血压的防治和研究都有重要意义．用类回归的方法,对所获得的大量样本数据进行分析,找出了高血压与年龄、城乡、饮酒、体重指数等多种因素之间的相关关系     

λ-DNA在锥形纳米孔中易位的研究

纳米孔是目前单分子测序的一项重要技术,文中利用聚焦离子束在氮化硅薄膜上制备了30/60 nm的锥形孔,并通过膜片钳装置对λ-DNA易位的电学信号进行了统计和分析.发现在一定的电场(＞200 mY)驱动下,DNA分子随着离子电流进入纳米孔,由于体积阻塞效应引起电流的下降.随着偏置电压的增大,阻塞电流也增大,同时易位的速度加快,DNA易位的弛豫时间减少.还可以根据阻塞信号的特点区分不同形貌的易位分子.     

语言接触中方言特征的易位研究——以临沂方言为个案

方言和普通话之间的接触是我国现行语言政策下语言接触的一种普遍现象。在和普通话的接触过程中,方言会逐渐变异,甚至可能出现典型特征的易位现象。和普通话的接触过程中,临沂方言的一些典型特征发生了变化,而文化、年龄、职业、性别等社会因素对语言易位有一定的制约作用。     

放射敏感性与染色体诱导易位的线形关系及其应用研究

应用荧光原位杂交（FISH）方法,研究人类恶性肿瘤细胞放射敏感性与照射后染色体易位畸变关系及其临床应用的可行性。采用3个放射敏感性不同的人类恶性肿瘤细胞株：鼻咽鳞癌（CNE）、肺腺癌（SPC－A1）和乳腺腺癌（MCF－7）。用常规集落形成方法,测定不同照射剂量下、不同敏感性肿瘤细胞的存活率。经秋水仙素阻断细胞分裂周期,低渗、固定等常规染色体制片过程和采用2,8号染色体涂染探针及FISH方法,测定照射后24h肿瘤细胞2,8号染色体内在的和辐射诱导的易位畸变量。结果发现,未照射的对照细胞内,2,8号染色体都存在不同程度的内在易位畸变。经分别照射2,4,6Gy后24h,CNE,SPC-A1和MCF－7细胞诱导生成的残存染色体易位畸变与照射剂量相关性强,能够反映细胞的放射敏感性;此外,所有细胞株中诱导生成的2,8号染色体易位畸变与细胞存活率也存在良好相关性,相关系数分别为0.97和0.98。该结果同时表明照射诱导易位畸变存在染色体簇性,与染色体大小无关。由此可见,诱导的残存染色体易位畸变与照射剂量呈线形关系。采用FISH方法计数照射诱导的残存染色体易位畸变,在预测不同的肿瘤细胞放射敏感性差异方面具有重要的临床意义。     

乳腺癌诊断指标的数理统计分析

以UCI机器学习知识库提供的683个乳腺癌数据为基础,利用相关分析、逐步线性回归和主成分分析等数理统计方法,对用于诊断检测乳腺癌各指标间的相互关系及主要判断指标进行了深入研究,指出细胞大小的均匀性(X2)、细胞形状的均匀性(X3)是检测乳腺癌诸指标中最重要的指标。     

Antibiotics in early life alter the murine colonic microbiome and adiposity

Antibiotics administered in low doses have been widely used as growth promoters in the agricultural industry since the 1950s, yet the mechanisms for this effect are unclear. Because antimicrobial agents of different classes and varying activity are effective across several vertebrate species, we proposed that such subtherapeutic administration alters the population structure of the gut microbiome as well as its metabolic capabilities. We generated a model of adiposity by giving subtherapeutic antibiotic therapy to young mice and evaluated changes in the composition and capabilities of the gut microbiome. Administration of subtherapeutic antibiotic therapy increased adiposity in young mice and increased hormone levels related to metabolism. We observed substantial taxonomic changes in the microbiome, changes in copies of key genes involved in the metabolism of carbohydrates to short-chain fatty acids, increases in colonic short-chain fatty acid levels, and alterations in the regulation of hepatic metabolism of lipids and cholesterol. In this model, we demonstrate the alteration of early-life murine metabolic homeostasis through antibiotic manipulation.     

A protein of the endoplasmic reticulum involved early in polypeptide translocation.

To identify components of the mammalian endoplasmic reticulum involved in the translocation of secretory proteins, crosslinking and reconstitution methods were combined. A multispanning abundant membrane glycoprotein was found which is in proximity to nascent chains early in translocation. In reconstituted proteoliposomes, this protein is stimulatory or required for the translocation of secretory proteins.     

Protein translocation across the eukaryotic endoplasmic reticulum and bacterial plasma membranes

A decisive step in the biosynthesis of many proteins is their partial or complete translocation across the eukaryotic endoplasmic reticulum membrane or the prokaryotic plasma membrane. Most of these proteins are translocated through a protein-conducting channel that is formed by a conserved, heterotrimeric membrane-protein complex, the Sec61 or SecY complex. Depending on channel binding partners, polypeptides are moved by different mechanisms: the polypeptide chain is transferred directly into the channel by the translating ribosome, a ratcheting mechanism is used by the endoplasmic reticulum chaperone BiP, and a pushing mechanism is used by the bacterial ATPase SecA. Structural, genetic and biochemical data show how the channel opens across the membrane, releases hydrophobic segments of membrane proteins laterally into lipid, and maintains the membrane barrier for small molecules.     

Preserving the membrane barrier for small molecules during bacterial protein translocation

Many proteins are translocated through the SecY channel in bacteria and archaea and through the related Sec61 channel in eukaryotes. The channel has an hourglass shape with a narrow constriction approximately halfway across the membrane, formed by a pore ring of amino acids. While the cytoplasmic cavity of the channel is empty, the extracellular cavity is filled with a short helix called the plug, which moves out of the way during protein translocation. The mechanism by which the channel transports large polypeptides and yet prevents the passage of small molecules, such as ions or metabolites, has been controversial. Here, we have addressed this issue in intact Escherichia coli cells by testing the permeation of small molecules through wild-type and mutant SecY channels, which are either in the resting state or contain a defined translocating polypeptide chain. We show that in the resting state, the channel is sealed by both the pore ring and the plug domain. During translocation, the pore ring forms a 'gasket-like' seal around the polypeptide chain, preventing the permeation of small molecules. The structural conservation of the channel in all organisms indicates that this may be a universal mechanism by which the membrane barrier is maintained during protein translocation.     

New variation on the translocation of proteins during early biogenesis of apolipoprotein B

Apolipoprotein B (apo B) is crucial for the transport of cholesterol in humans. It is a large secretory protein that mediates the uptake of low-density lipoproteins and renders several forms of lipid droplets soluble in the blood. The binding of lipid by apo B also prevents this hydrophobic protein from precipitating in aqueous solution. In the endoplasmic reticulum, nascent secretory proteins must be translocated through an aqueous channel in the membrane into the aqueous lumen, so some novel form of processing may be necessary to maintain the solubility of apo B during its translocation. We have discovered that the biogenesis of apo B in cell-free systems does indeed involve a new variation on protein translocation: unlike typical secretory proteins, apo B is synthesized as a series of transmembrane chains with large cytoplasmic domains and progressively longer amino-terminal regions that are protected against added proteases during the translocation process. In contrast to typical transmembrane proteins, these transmembrane chains are not integrated into the bilayer. Moreover, the transmembrane chains with the shortest protected domains are precursors of forms whose protection is progressively extended to cover the length of the protein. This stepwise conversion occurs post-translationally for the most part. We propose a model on the basis of these findings for the biogenesis of apo B.     

水平极化移动接收天线的研究与设计

在移动通信领域,移动接收采用垂直极化方式,因此移动接收天线可以采用垂直极化方式的偶板子天线.由于垂直极化天线在水平方向的方向图是全向的,因此可以在相对于发射天线的任何方向上都不改变接收天线的方向性.随着数字电视时代的到来,电视的移动接收成为数字电视的一项重要特征.但是在以往的模拟电视广播中,电视广播信号通常是水平极化的,因此在数字电视的移动接收时,或者需要改变信号发射的极化方式,或者设计一种新的可以用于移动接收目的的接收天线.本文给出一种可以用于接收水平极化信号的移动接收天线的设计方案和理论分析.通过理论分析表明,此种天线可以在移动过程自适应地完成接收水平极化信号的要求.     

早期成岩作用研究进展及发展方向

早期成岩作用作为一个重要的研究领域受到广泛关注。概括总结了早期成岩作用的主要特点、地质响应和研究思路，介绍了在元素的迁移转化、硫酸盐还原反应、数学模型及微生物成岩等理论领域和多金属结核及早期成岩成矿、环境沉积学、土壤性质评价与改良等应用领域的主要研究进展。早期成岩作用研究具有广阔的发展前景，未来可能在以下3方面快速取得突破：研究区域将进一步扩大，湖泊、三角洲及土壤中的相应研究将得以加强；多层的稳态或非稳态的一维、二维或三维的早期成岩数学模型将得以建立；其研究方法和理论成果将被广泛应用于环境沉积学及环境监测和治理等领域中。     

早期成岩作用研究进展及发展方向

早期成岩作用作为一个重要的研究领域受到广泛关注。概括总结了早期成岩作用的主要特点、地质响应和研究思路,介绍了在元素的迁移转化、硫酸盐还原反应、数学模型及微生物成岩等理论领域和多金属结核及早期成岩成矿、环境沉积学、土壤性质评价与改良等应用领域的主要研究进展。早期成岩作用研究具有广阔的发展前景,未来可能在以下3方面快速取得突破:研究区域将进一步扩大,湖泊、三角洲及土壤中的相应研究将得以加强;多层的稳态或非稳态的一维、二维或三维的早期成岩数学模型将得以建立;其研究方法和理论成果将被广泛应用于环境沉积学及环境监测和治理等领域中。