Epitope-Imprinted Nanoparticles as Transforming Growth Factor-β3 Sequestering Ligands to Modulate Stem Cell Fate

Growth factors (GFs) are biomolecules with potent biological effects but inherent limitations hinder their potential as therapeutic agents and cell culture supplements in tissue engineering and regenerative medicine (TERM). Biomaterials that sequester endogenous GFs by affinity binding might circumvent such limitations and thus are being increasingly investigated. Here, molecularly imprinted nanoparticles (MINPs) are proposed as specific abiotic ligands for GFs. As a proof of concept, a conformational epitope of transforming growth factor-β3 (TGF-β3) is designed and surface imprinted onto polyacrylamide-based nanoparticles by inverse microemulsion polymerization. It is found that, depending on the polymerization mixture composition, MINPs can recognize and preferentially bind TGF-β3, either in noncompetitive assays or from a complex human fluid (platelet lysate). Substrates functionalized with MINPs are then used for 2D culture of adipose-derived stem cells. Remarkably, gene and protein expression profiles show a marked upregulation of SOX-9, suggesting activation of TGF-β3 signaling pathways without requiring supplementation with exogenous GF. Likewise, culturing these cells in pellets incorporating MINPs previously incubated with platelet lysate results in higher collagen II-rich matrix deposition, compared to pellets incorporating non-imprinted nanoparticles. In summary, results suggest MINPs can be used as cost-effective, stable, and scalable alternative abiotic GF ligands to guide cell fate in TERM applications.     

Water Vapor Permeability of Whey Protein Emulsion Films as Affected by pH

The water vapor permeability (WVP) of whey protein isolate-beeswax emulsion films was investigated as related to pH. Lower WVP was observed for films cast from solutions at pH 7.0. When pH of the film-forming solution was lowered, resulting film WVP increased. At the isoelectric point, WVP was the highest. As pH of the emulsion approached pI, a sharp change in viscosity occurred due to an increase in protein aggregation. This increase in viscosity probably lowered lipid mobility and reduced interconnectivity among lipid droplets, resulting in the higher WVP. For minimum WVP, such films should be applied at pH different from pI.     

大豆蛋白的吸水和持水性能

对大豆蛋白的吸水和持水性能及其影响因素进行了论述,大豆蛋白制品吸水能力的差别很小,一般为 ４０ ｇ 水／１００ ｇ 蛋白～６０ ｇ 水／１００ ｇ 蛋白。大豆蛋白制品的持水能力差别很大,约为１３０ ｇ 水／１００ ｇ 蛋白～６２５ ｇ 水／１００ ｇ 蛋白,持水性能在本质上是蛋白分子物理截留水的能力,其影响因素包括蛋白分子大小、形状、空间、构象等。高分子物理方法是一种新的研究方法,对这个方法在大豆蛋白吸水及持水性能方面的应用进行了讨论。     

Effects of cultivar and soil fertility on grain protein yield,grain protein content,flour yield and breadmaking quality of wheat

Grain protein content affects the flour yield and breadmaking characteristics of wheat (Triticum aestivum L). In this study, grain protein yield, grain protein content, flour yield and loaf volume were quantified for four wheat cultivars (Inia, Carina, Kariega and SST 86) grown under six different soil fertility regimes in a long-term fertilisation and irrigation experiment at the University of Pretoria. The experimental design was a randomised complete block replicated four times, with fertility as the main plots and cultivars as the subplot treatments. Grain protein yield, flour yield, loaf volume and mixograph dough peak mixing time varied among cultivars and soil fertility situations. Grain protein content differed among cultivars, but mixograph water absorption and dough characteristics did not differ. The highest grain protein yield was 873 kg ha⁻¹ for Carina and the lowest 527 kg ha⁻¹ for SST 86. Grain protein content averaged 131 g kg⁻¹ for Carina and 122 g kg⁻¹ for Kariega. Breadmaking performance showed that in a well-balanced soil fertility situation, Kariega produced 1025 cm³ of loaf volume while Inia averaged 950 cm³. Grain protein yield increased with increasing soil fertility, but grain protein content, flour yield, loaf volume, water absorption and mixograph peak mixing time varied with soil fertility. The interaction between cultivar and soil fertility was significant for grain protein yield, grain protein content, flour yield, loaf volume and water absorption but not dough peak mixing time. The results indicate cultivar differences in breadmaking quality characteristics and that soil fertility status affects grain protein yield, grain protein content, flour yield, loaf volume potential and water absorption but not mixograph peak mixing time and dough characteristics. © 1999 Society of Chemical Industry     

Analysis of the peroxisomal acyl‐CoA oxidase gene product from Pichia pastoris and determination of its targeting signal

Acyl‐CoA oxidase (Pox1p) is involved in the β‐oxidation of fatty acids and is targeted to the peroxisomal matrix via the use of different signals in various organisms. In rat, mouse and human, Pox1p contains a canonical peroxisomal targeting signal 1 (PTS1), whereas in the yeasts Candida tropicalis, Saccharomyces cerevisiae, C. maltosa and Yarrowia lipolytica neither a PTS1 nor a PTS2 sequence is present, suggesting that Pox1p might be targeted to the peroxisomes via a third unknown pathway. Alternatively, since proteins lacking a PTS sequence can enter peroxisomes in association with other polypeptides containing a PTS, Pox1p might ‘piggy‐back’ its way into the peroxisomal matrix together with other proteins. To understand the mechanism of peroxisomal targeting of a yeast Pox1p, we cloned the Pichia pastoris POX1 gene to study the pathway of import of PpPox1p into peroxisomes. The gene was cloned by PCR, hybridization and plasmid rescue. The 2157 bp gene encodes a protein with a predicted molecular weight of 80 kDa. Antisera against PpPox1p detected a protein specifically induced on oleate with an apparent molecular weight of 72 kDa. Immunolocalization studies confirmed the peroxisomal localization of PpPox1p. The carboxy‐terminus of PpPox1p ends with a PTS1‐like sequence, APKI. The sequence PKI was necessary for transport of PpPox1p into peroxisomes and interacted with the PTS1 receptor, Pex5p. Furthermore, addition of the sequence APKI to the C‐terminus of the green fluorescent protein directed this fusion protein to the peroxisome. Therefore, PpPox1p uses the PTS1 pathway for its import into peroxisomes. Copyright © 1999 John Wiley & Sons, Ltd.     

基于功率型LED的在体整体荧光光学成像

用发光二极管（LED）替代常用的荧光激发光源汞灯,以实现基于LED的整体荧光光学成像（简称整体成像）。首先通过光谱计算分析,探讨了在不同波段与汞灯激发的荧光量相当时LED需要输出的光通量。以此为依据选择LED,构建了基于功率型LED的整体成像系统,用其动态监测绿色荧光蛋白（GFP）标记的肿瘤在裸鼠体内生长和药物治疗过程。实验表明,功率型LED可在类似于整体成像需要较大光功率的场合中应用。光源替代时,若两光源的光谱在选择的波段内分布不一样,则有必要考虑不同波长的光激发荧光效率差异的影响。     

细胞可溶性蛋白准弹性激光散射分析与SDS-PAGE法比较研究

分别采用SDS-PAGE和准弹性激光散射检测柠檬醛作用白血病K562前后细胞可溶性蛋白变化情况。实验结果表明：SDS-PAGE与准弹性激光散射均能检测出可溶性蛋白种类、大小、含量及其变化：但准弹性激光散射法所获取的参数信息反映了可溶性蛋白天然构象下的真实状态及其动态变化,与传统的SDS-PAGE方法相比较,它是研究外界因素（包括药物）对细胞可溶性蛋白尤其是对蛋白聚合体影响的更好表征方法。     

系统性红斑狼疮患者血液中PRDM1和CD138＋浆细胞表达的研究

目的;探讨系统性红斑狼疮（SiE）患者和正常人之间PRDM1和CD138＋浆细胞的差异。方法：40例SLE患者血液标本,30例健康体检血液标本,抽取RNA、利用逆转录聚合酶链反应（RT—PCR）技术研究PRDM1基因表达;收集外周血单个核细胞,利用流式细胞技术研究CD138＋浆细胞量的差异。结果：SLE患者组血液中的P...     

BAY41-4109对乙肝病毒衣壳组装的影响

乙肝病毒衣壳蛋白成功组装成衣壳二十面体的过程是病毒前基因组RNA逆转录形成成熟DNA的必要步骤。衣壳结构的轻微改变或破坏能对病毒子代传播产生巨大影响。应用透射电子显微镜研究发现小分子抗病毒化合物（heteroaryldihvdropyrimidine,HAP）BAY41．4109在与衣壳蛋白二聚体摩尔浓度比达到1：2时,能干扰乙肝病毒衣壳蛋白组装成衣壳二十面体。在BAY41—4109的作用下,衣壳蛋白发生错误组装,形成不规则球体、平面片状结构和管状结构。应用图像处理技术对管状结构进行分析,发现它是衣壳蛋白重新装配形成的具有螺旋对称性的规则组装体,衣壳蛋白按六角晶格方式排列,其最小组成单位是衣壳蛋白的二聚体。     

A Protein-Adsorbent Hydrogel with Tunable Stiffness for Tissue Culture Demonstrates Matrix-Dependent Stiffness Responses

Although tissue culture plastic has been widely employed for cell culture, the rigidity of plastic is not physiologic. Softer hydrogels used to culture cells have not been widely adopted in part because coupling chemistries are required to covalently capture extracellular matrix (ECM) proteins and support cell adhesion. To create an in vitro system with tunable stiffnesses that readily adsorbs ECM proteins for cell culture, a novel hydrophobic hydrogel system is presented via chemically converting hydroxyl residues on the dextran backbone to methacrylate groups, thereby transforming non-protein adhesive, hydrophilic dextran to highly protein adsorbent substrates. Increasing methacrylate functionality increases the hydrophobicity in the resulting hydrogels and enhances ECM protein adsorption without additional chemical reactions. These hydrophobic hydrogels permit facile and tunable modulation of substrate stiffness independent of hydrophobicity or ECM coatings. Using this approach, it is shown that substrate stiffness and ECM adsorption work together to affect cell morphology and proliferation, but the strengths of these effects vary in different cell types. Furthermore, it is revealed that stiffness-mediated differentiation of dermal fibroblasts into myofibroblasts is modulated by the substrate ECM. The material system demonstrates remarkable simplicity and flexibility to tune ECM coatings and substrate stiffness and study their effects on cell function.