Dielectric Properties and Relaxation in (1−x)BiScO3–xBa(Mg1/3Nb2/3)O3 Solid Solutions

The dielectric properties and frequency dispersion associated with a dielectric relaxation were evaluated within the perovskite (1− x )BiScO₃– x Ba(Mg_1/3Nb_2/3)O₃ solid solution systems (0.7 ≤ x ≤ 1). With increasing BiScO₃, the room-temperature dielectric permittivity at low frequency (100 Hz) increased up to 115 at x = 0.7, and a dielectric relaxation phenomenon was evident. Relaxation parameters were analyzed using several Arrhenius-type equations, and the microwave dielectric property measurement using rectangular wave-guide method enabled confirmation of the extrapolated value of the Arrhenius plot. The result of the microwave dielectric property measurement was also checked with J -function fitting based on the frequency-dependent Gaussian distribution of the associated dielectric loss data at low frequency.     

Decreased Fibroblast and Increased Osteoblast Functions on Ionic Plasma Deposited Nanostructured Ti Coatings

Bioactive coatings are in high demand to control cellular functions for numerous medical devices. The objective of this in vitro study was to characterize for the first time fibroblast (fibrous scar tissue forming cells) adhesion and proliferation on an important polymeric biomaterial (silicone) coated with titanium using a novel ionic plasma deposition (IPD) process. Fibroblasts are one of the first anchorage-dependent cells to arrive at an implant surface during the wound healing process. Persistent excessive functions of fibroblasts have been linked to detrimental fibrous tissue formation which may cause implant failure. The IPD process creates a surface-engineered nanostructure (with features usually below 100 nm) by first using a vacuum to remove all contaminants, then guiding charged metallic ions or plasma to the surface of a medical device at ambient temperature. Results demonstrated that compared to currently used titanium and uncoated silicone, silicone coated with titanium using IPD significantly decreased fibroblast adhesion and proliferation. Results also showed competitively increased osteoblast (bone-forming cells) over fibroblast adhesion on silicone coated with titanium; in contrast, osteoblast adhesion was not competitively increased over fibroblast adhesion on uncoated silicone or titanium controls. In this manner, this study strongly suggests that IPD should be further studied for biomaterial applications in which fibrous tissue encapsulation is undesirable (such as for orthopedic implants, cardiovascular components, etc.).     

Micelle‐Enhanced Bioorthogonal Labeling of Genetically Encoded Azido Groups on the Lipid‐Embedded Surface of a GPCR

Genetically encoded p‐azido‐phenylalanine (azF) residues in G protein‐coupled receptors (GPCRs) can be targeted with dibenzocyclooctyne‐modified (DIBO‐modified) fluorescent probes by means of strain‐promoted [3+2] azide–alkyne cycloaddition (SpAAC). Here we show that azF residues situated on the transmembrane surfaces of detergent‐solubilized receptors exhibit up to 1000‐fold rate enhancement relative to azF residues on water‐exposed surfaces. We show that the amphipathic moment of the labeling reagent, consisting of hydrophobic DIBO coupled to hydrophilic Alexa dye, results in strong partitioning of the DIBO group into the hydrocarbon core of the detergent micelle and consequently high local reactant concentrations. The observed rate constant for the micelleenhanced SpAAC is comparable with those of the fastest bioorthogonal labeling reactions known. Targeting hydrophobic regions of membrane proteins by use of micelle‐enhanced SpAAC should expand the utility of bioorthogonal labeling strategies.     

Validation of Tuba1a as Appropriate Internal Control for Normalization of Gene Expression Analysis during Mouse Lung Development

The expression ratio between the analysed gene and an internal control gene is the most widely used normalization method for quantitative RT-PCR (qRT-PCR) expression analysis. The ideal reference gene for a specific experiment is the one whose expression is not affected by the different experimental conditions tested. In this study, we validate the applicability of five commonly used reference genes during different stages of mouse lung development. The stability of expression of five different reference genes (Tuba1a, Actb Gapdh, Rn18S and Hist4h4) was calculated within five experimental groups using the statistical algorithm of geNorm software. Overall, Tuba1a showed the least variability in expression among the different stages of lung development, while Hist4h4 and Rn18S showed the maximum variability in their expression. Expression analysis of two lung specific markers, surfactant protein C (SftpC) and Clara cell-specific 10 kDA protein (Scgb1a1), normalized to each of the five reference genes tested here, confirmed our results and showed that incorrect reference gene choice can lead to artefacts. Moreover, a combination of two internal controls for normalization of expression analysis during lung development will increase the accuracy and reliability of results.     

Transformation of Free and Dipeptide‐Bound Glycated Amino Acids by Two Strains of Saccharomyces cerevisiae

The yeast Saccharomyces cerevisiae transforms branched‐chain and aromatic amino acids into higher alcohols in the Ehrlich pathway. During microbiological culturing and industrial fermentations, this yeast is confronted with amino acids modified by reducing sugars in the Maillard reaction (glycation). In order to gain some preliminary insight into the physiological “handling” of glycated amino acids by yeasts, individual Maillard reaction products (MRPs: fructosyllysine, carboxymethyllysine, pyrraline, formyline, maltosine, methylglyoxal‐derived hydroimidazolone) were administered to two strains of S. cerevisiae in a rich medium. Only formyline was converted into the corresponding α‐hydroxy acid, to a small extent (10 %). Dipeptide‐bound pyrraline and maltosine were removed from the medium with concomitant emergence of several metabolites. Pyrraline was mainly converted into the corresponding Ehrlich alcohol (20–60 %) and maltosine into the corresponding α‐hydroxy acid (40–60 %). Five specific metabolites of glycated amino acids were synthesized and characterized. We show for the first time that S. cerevisiae can use glycated amino acids as a nitrogen source and transform them into new metabolites, provided that the substances can be transported across the cell membrane.     

高温高压水中镍基合金表面氧化膜的原位表面增强型拉曼光谱

采用表面增强型拉曼光谱方法原位研究了镍基合金在高温高压水环境中的腐蚀行为及其表面生成氧化膜.Ni-5Cr-8Fe表面氧化膜的拉曼光谱存在三个拉曼峰,位于540 cm-1,610 cm-1和670 cm-1.610 cm-1峰的出现表明了氧化膜中存在Cr2 O3.540 cm-1峰则说明氧化膜中含有Cr2 O3或NiO或两者的混合物.670 cm-1峰对应于FeCr2O4尖晶石的生成.Ni-10Cr-8Fe的表面氧化膜由Cr2 O3、FeCr2O4构成,可能含有一定的NiO.Ni-10Cr和Ni-20Cr的表面氧化膜主要为Cr2 O3,没有发现尖晶石相的存在.随着合金中铬含量的增加,表面氧化膜中Cr2O3的含量增加,NiO成分减少.     

Differential scanning calorimetric and free volume study of reactive compatibilization by EPM‐g‐MA of poly(trimethylene terephthalate)/EPDM blends

Differential scanning calorimetry (DSC) and positron annihilation lifetime measurements have been carried out to study the effect of the compatibilizer maleic anhydride grafted ethylene propylene copolymer (EPM‐g‐MA) in poly trimethylene terephthalate and ethylene propylene diene monomer (PTT/EPDM) immiscible blends. The DSC results for the blends of 50/50 and 30/70 compositions show two clear glass transition temperatures, indicating that the blends are two‐phase systems. With the addition of compatibilizer, the separation between the two glass transitions decreased, suggesting an increased interaction between the blend components with compatibilizer. At 5 wt % of compatibilizer, the separation between the T_gs reduced in both 50/50 and 30/70 blends. The positron results for the blends without compatibilizer showed an increase in relative fractional free volume, as the EPDM content in the blend is increased. This suggests the coalescence of free volume of EPDM with the free volumes of PTT due to phase separation. However, the effect of compatibilizer in the blends was clearly seen with the observed minimum in free volume parameters at 5% of the compatibilizer, further suggesting that this percent of compatibilizer seems to be the optimum value for these blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 740–747, 2006     

Egg Consumption Modulates HDL Lipid Composition and Increases the Cholesterol-Accepting Capacity of Serum in Metabolic Syndrome

We recently demonstrated that daily whole egg consumption during moderate carbohydrate restriction leads to greater increases in plasma HDL-cholesterol (HDL-C) and improvements in HDL profiles in metabolic syndrome (MetS) when compared to intake of a yolk-free egg substitute. We further investigated the effects of this intervention on HDL composition and function, hypothesizing that the phospholipid species present in egg yolk modulate HDL lipid composition to increase the cholesterol-accepting capacity of subject serum. Men and women classified with MetS were randomly assigned to consume either three whole eggs (EGG, n = 20) per day or the equivalent amount of egg substitute (SUB, n = 17) throughout a 12-week moderate carbohydrate-restricted (25–30 % of energy) diet. Relative to other HDL lipids, HDL-cholesteryl ester content increased in all subjects, with greater increases in the SUB group. Further, HDL-triacylglycerol content was reduced in EGG group subjects with normal baseline plasma HDL-C, resulting in increases in HDL-CE/TAG ratios in both groups. Phospholipid analysis by mass spectrometry revealed that HDL became enriched in phosphatidylethanolamine in the EGG group, and that EGG group HDL better reflected sphingomyelin species present in the whole egg product at week 12 compared to baseline. Further, macrophage cholesterol efflux to EGG subject serum increased from baseline to week 12, whereas no changes were observed in the SUB group. Together, these findings suggest that daily egg consumption promotes favorable shifts in HDL lipid composition and function beyond increasing plasma HDL-C in MetS.     

Aromatase and dual aromatase-steroid sulfatase inhibitors from the letrozole and vorozole templates

Concurrent inhibition of aromatase and steroid sulfatase (STS) may provide a more effective treatment for hormone‐dependent breast cancer than monotherapy against individual enzymes, and several dual aromatase–sulfatase inhibitors (DASIs) have been reported. Three aromatase inhibitors with sub‐nanomolar potency, better than the benchmark agent letrozole, were designed. To further explore the DASI concept, a new series of letrozole‐derived sulfamates and a vorozole‐based sulfamate were designed and biologically evaluated in JEG‐3 cells to reveal structure–activity relationships. Amongst achiral and racemic compounds, 2‐bromo‐4‐(2‐(4‐cyanophenyl)‐2‐(1H‐1,2,4‐triazol‐1‐yl)ethyl)phenyl sulfamate is the most potent DASI (aromatase: IC₅₀=0.87 nM ; STS: IC₅₀=593 nM ). The enantiomers of the phenolic precursor to this compound were separated by chiral HPLC and their absolute configuration determined by X‐ray crystallography. Following conversion to their corresponding sulfamates, the S‐(+)‐enantiomer was found to inhibit aromatase and sulfatase most potently (aromatase: IC₅₀=0.52 nM ; STS: IC₅₀=280 nM ). The docking of each enantiomer and other ligands into the aromatase and sulfatase active sites was also investigated.