Simulation and evaluation of 3D traction force microscopy

Measuring cell-generated forces by Traction Force Microscopy (TFM) has become a standard tool in cell mechanobiology. Although widely used in two dimensional (2D) experiments, only a few methods exist to measure traction in three-dimensional (3D) cell culture, since 3D volumetric high-resolution microscopy and more demanding computational approaches are required. Although it is commonly known that the selected experimental and computational setup highly influence the quality and accuracy of the results, no existing methods can adequately assess the errors involved in this process. We present a fully integrated simulation and evaluation platform that allows one to simulate TFM images and quantify errors of an applied approach for traction stress reconstruction, in order to improve experiments that attempt to measure mechanical interaction in cellular systems. In this context, we show that a careful parameter selection can decrease the reconstructed traction error by up to 40%.     

长沙市不同污染程度区域桂花和香樟叶表面PM2.5吸附量及其影响因素

为阐释不同污染程度下城市绿化植物吸滞PM_2.5机理、解析污染物来源,应用气溶胶再发生器定量测定长沙市常见的2种园林绿化树种(桂花和香樟)植物叶片PM_2.5吸附量,同时应用原子力显微镜(AFM)观察了不同污染区(交通区、文教区、清洁区)植被的叶表面微形态特征,使用离子色谱仪测定样品中水溶性离子含量.结果表明: 污染程度与植物叶表面PM_2.5吸附量呈正相关,不同植物单位叶面积PM_2.5吸附量全年均值表现为交通区(0.56±0.04 μg·cm^-2)＞文教区(0.48±0.06 μg·cm^-2)＞清洁区(0.33±0.02 μg·cm^-2),植物单位叶面积PM_2.5吸附量季节变化为冬季(0.70±0.10 μg·cm^-2)＞春季(0.43±0.14 μg·cm^-2)＞秋季(0.39±0.12 μg·cm^-2)＞夏季(0.31±0.09 μg·cm^-2),桂花的单位叶面积PM_2.5吸附量大于香樟;污染程度轻的区域的植物叶片比较光滑,污染程度重的区域的叶片较粗糙,植物粗糙度排序为交通区(195.45±16.09 nm)＞文教区(176.99±8.45 nm)＞清洁区(131.88±12.98 nm);不同污染程度地区PM_2.5离子含量均表现为冬季最大,其次是春季和秋季,夏季最低;3个污染区PM_2.5离子成分均以Na⁺、NH₄⁺、Cl^-和Br^-这4种离子为主,不同程度污染区PM_2.5污染均以移动源污染为主.     

黑果枸杞提取物泡腾片的制备及其质量评价

为了解决黑果枸杞中花青素稳定性问题,本文采用Box-Behnken设计对黑果枸杞提取物泡腾片配方进行优化,并对其进行质量评价。采用酸碱混合制粒压片法,通过单因素实验,筛选出片剂所需的辅料:崩解剂、填充剂、润滑剂以及甜味剂。采用响应面试验,结合感官评价进行处方优化,从而确定最优配方:柠檬酸32%、黑果枸杞提取物25%、碳酸氢钠24%、乳糖15%、甜蜜素3%、聚乙二醇6000 1%;对最优配方进行质量评价,各项指标均符合规定,其中花青素含量为8.06 mg/g。该泡腾片表面光滑,泡腾效果好,具有黑果枸杞香气,为实际生产提供理论依据。     

Adaptable mesocosm facility to study oil spill impacts on corals

Although numerous studies have been carried out on the impacts of oil spills on coral physiology, most have relied on laboratory assays. This scarcity is partly explained by the difficulty of reproducing realistic conditions in a laboratory setting or of performing experiments with toxic compounds in the field. Mesocosm systems provide the opportunity to carry out such studies with safe handling of contaminants while reproducing natural conditions required by living organisms. The mesocosm design is crucial and can lead to the development of innovative technologies to mitigate environmental impacts. Therefore, this study aimed to develop a mesocosm system for studies simulating oil spills with several key advantages, including true replication and the use of gravity to control flow‐through that reduces reliance on pumps that can clog thereby decreasing errors and costs. This adaptable system can be configured to (a) have continuous flow‐through; (b) operate as an open or closed system; (c) be fed by gravity; (d) have separate mesocosm sections that can be used for individual and simultaneous experiments; and (e) simulate the migration of oil from ocean oil spills to the nearby reefs. The mesocosm performance was assessed with two experiments using the hydrocoral Millepora alcicornis and different configurations to simulate two magnitudes of oil spills. With few exceptions, physical and chemical parameters remained stable within replicates and within treatments throughout the experiments. Physical and chemical parameters that expressed change during the experiment were still within the range of natural conditions observed in Brazilian marine environments. The photosynthetic potential (F_v/F_m) of the algae associated with M. alcicornis decreased in response to an 1% crude‐oil contamination, suggesting a successful delivery of the toxic contaminant to the targeted replicates. This mesocosm is customizable and adjustable for several types of experiments and proved to be effective for studies of oil spills.     

基于主成分-聚类-逐步回归分析构建番茄苗期耐铝性综合评价体系

铝毒是限制酸性土壤中作物产量的主要因素之一。番茄(Solanum lycopersicum)是适合在酸性土壤中种植的主要经济作物, 不同品种番茄对铝胁迫的响应存在差异, 因此, 筛选苗期耐铝毒种质对番茄生产及研究具有重要意义。以10个番茄品种为材料, 采用室内土培盆栽, 设置1 000 µmol∙L^-1 AlCl₃·6H₂O处理, 测定反映植物铝胁迫下生长状况的16个形态、生理生化及光合指标。通过主成分分析, 将铝胁迫下番茄幼苗的16个指标转化为5个独立的综合指标, 累积贡献率达90.779%。基于耐铝性综合评价值(A)的系统聚类分析, 将供试种质划分为5类, 第I类为高度耐铝品种Qianxi, 第V类为高度不耐铝品种Puluowangsi。经多元线性逐步回归分析得出番茄苗期耐铝评价方程: y=0.046+0.405X₆+0.515X₁₀-0.207X₁₅+0.028X₃ (R²=0.997), 从16个指标中提取出与A值显著相关(P<0.01)的4个指标: 丙二醛含量(X₃)、净光合速率(X₆)、叶面积(X₁₀)和地下部干重(X₁₅)。利用评价方程可判断不同番茄品种苗期的耐铝性, 使番茄耐铝性鉴定工作快速简便。     

Probable blind spot in the International Diabetes Federation definition of metabolic syndrome

Objectives: The International Diabetes Federation (IDF) proposed a novel definition of the metabolic syndrome (MS) in 2005, which designated central obesity as mandatory. The new National Cholesterol Education Program (NCEP) version, announced by the American Heart Association and National Heart Lung and Blood Institute in October 2005, did not favor any of the five components. We set out to compare the cardiovascular profiles of patients cross‐defined by these two definitions to shed light on the differential meanings of the two. Research Methods and Procedures: We analyzed data from 2608 non‐institutionalized adults (≥19 years old) in the National Nutrition and Health Survey in Taiwan, who had complete data for the five MS defining components. Both definitions adopted lower cut‐points for fasting glucose and race‐specific cut‐points for waist circumference. Results: Under the IDF's and new NCEP's definitions, the MS prevalence was 6.2% and 11.6% in men and 12.6% and 16.5% in women, respectively. Although the two definitions had high agreement, IDF failed to pick up ～4% to 5% of people with more than three MS component disorders but a waist circumference less than the cut‐point. Subjects whose physical conditions only satisfied NCEP's definition had similar or worse metabolic profiles than those whose conditions satisfied both IDF's definition and the new NCEP's definition. Discussion: The IDF definition would fail to identify a portion of people who have more than three MS component disorders but a small waistline. Further research and discussion are needed on whether and how to implement the IDF's definition.     

Interventions to prevent or treat obesity in preschool children: a review of evaluated programs

Objective: To identify effective programs to prevent or treat overweight among 2‐ to <6‐year‐old children. Research Methods and Procedures: We searched six databases to identify evaluated intervention programs assessing changes in weight status or body fat and systematically summarized study attributes and outcomes. Results: Four of the seven studies (two intervention, two prevention) documented significant reductions in weight status or body fat. Among these, three sustained reductions at 1 or 2 years after program initiation, three incorporated a framework/theory, two actively and one passively involved parents, three included multicomponent strategies, and all four monitored behavioral changes. Of the three (prevention) studies that did not show reduction in weight or fat status, all performed assessments between 4 and 9 months after program initiation, and one used a multicomponent strategy. Other significant changes reported were reductions in television viewing, cholesterol, and parental restriction of child feeding. Discussion: The paucity of studies limits our ability to generalize findings. Among the available studies, multicomponent programs with 1‐ to 2‐year follow‐up in clinics or child care settings were successful in their impact on weight; they were likely enhanced by parental involvement. Both treatment programs and two of five prevention programs reduced weight/fat status. Our review highlights the need to evaluate more programs, advocate for use of a framework/behavioral theory and objective behavioral measures, further examine the impact of involving parents and the impact of intervention duration and follow‐up time, strengthen prevention programs, and further evaluate successful programs in other settings and among other racial/ethnic groups.