Development and critical evaluation of fluorescent chloride nanosensors

In this study, we describe the preparation and evaluation of new fluorescent sensor nanoparticles for the ratiometric measurement of chloride concentrations. Both a chloride-sensitive dye (lucigenin) and a reference dye (sulforhodamine derivative) were incorporated into polyacrylamide nanoparticles via inverse microemulsion polymerization and investigated for their response to chloride ions in buffered suspension as well as in living cells. The fluorescence intensity of lucigenin reversibly decreased in the presence of chloride ions due to a collisional quenching process, which can be described with the Stern-Volmer equation. The determined Stern-Volmer constant K SV for the quenching of lucigenin incorporated into particles was found to be 53 M (-1) and is considerably smaller than the Stern-Volmer constant for quenching of free lucigenin ( K SV = 250 M (-1)) under the same conditions. To test the nanosensors in living cells, we incorporated them into Chinese hamster ovary cells and mouse fibroblasts by using the conventional lipofectamin technique and monitored the response to changing chloride concentrations in the cell.     

Stearidonic Acid-Enriched Soybean Oil Increased the Omega-3 Index, an Emerging Cardiovascular Risk Marker

A plant source of omega-3 fatty acid (FA) that can raise tissue eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA) is needed. A soybean oil (SBO) containing approximately 20% stearidonic acid [SDA; the delta-6 desaturase product of alpha-linolenic acid (ALA)] derived from genetically modified soybeans is under development. This study compared the effects of EPA to SDA-SBO on erythrocyte EPA+DHA levels (the omega-3 index). Overweight healthy volunteers (n=45) were randomized to SDA-SBO (24 ml/day providing approximately 3.7 g SDA) or to regular SBO (control group) without or with EPA ethyl esters (approximately 1 g/day) for 16 weeks. Serum lipids, blood pressure, heart rate, platelet function and safety laboratory tests were measured along with the omega-3 index. A per-protocol analysis was conducted on 33 subjects (11 per group). Compared to baseline, average omega-3 index levels increased 19.5% in the SDA group and 25.4% in the EPA group (p<0.05 for both, vs. control). DHA did not change in any group. Relative to EPA, SDA increased RBC EPA with about 17% efficiency. No other clinical endpoints were affected by SDA or EPA treatment (vs. control). In conclusion, SDA-enriched SBO significantly raised the omega-3 index. Since EPA supplementation has been shown to raise the omega-3 index and to lower risk for cardiac events, SDA-SBO may be a viable plant-based alternative for providing meaningful intakes of cardioprotective omega-3 FAs.     

Inhibition of Salmonella-induced IL-8 synthesis and expression of Hsp70 in enterocyte-like Caco-2 cells after exposure to non-starter lactobacilli

Oral administration of lactobacilli as probiotics is gaining importance in the treatment of intestinal inflammations. We investigated the effect of non-starter lactobacilli Lactobacillus casei subsp casei 2756, Lactobacillus curvatus 2775, and Lactobacillus plantarum 2142 as well as their spent culture supernatants (SCS) on Salmonella enteritidis 857 growth, interleukin (IL)-8 and heat shock protein 70 (Hsp70) synthesis in undifferentiated crypt-like and differentiated villus-like Caco-2 cells. The cells were infected with graded numbers of non-starter lactobacilli or S. enteritidis 857 for 1 h and allowed to recover for 24 h or exposed to 200 bacteria/cell for 1 h and allowed to recover for different periods of time. In another experiment S. enteritidis 857 was first pre-treated with SCS-lactobacilli for 1 h before infecting the cells. The levels of IL-8 and Hsp70 were assessed using sandwich ELISA and immunostaining of Western blots, respectively. The effect of SCS-lactobacilli on S. enteritidis 857 growth was evaluated by agar plate diffusion test. The non-starter lactobacilli induced a significant increase in the levels of both IL-8 and Hsp70. However, compared with the S. enteritidis 857 induced IL-8 synthesis, the levels of IL-8 induced by the lactobacilli at any equivalent bacterial number were far lower. After exposure of Caco-2 cells to S. enteritidis 857 pre-treated with SCS-lactobacilli, it appeared that their SCS inhibited the S. enteritidis 857 growth and IL-8 synthesis and in addition induced the expression of Hsp70. The differences in response of crypt- and villus-like Caco-2 cells are merely a reflection of their differentiation status. Our data suggest that the beneficial effect of non-starter lactobacilli to the intestinal inflammations might be associated with a decrease of the IL-8 levels. This effect could be mediated, at least in part, by the bacteria themselves or via a secreted antimicrobial product(s) either directly against the pathogens or indirectly through the synthesis of Hsp70.     

Fast Self-Assembly Dynamics of a β-Sheet Peptide Soft Material

Peptide-based hydrogels are promising biocompatible materials for wound healing, drug delivery, and tissue engineering applications. The physical properties of these nanostructured materials depend strongly on the morphology of the gel network. However, the self-assembly mechanism of the peptides that leads to a distinct network morphology is still a subject of ongoing debate, since complete assembly pathways have not yet been resolved. To unravel the dynamics of the hierarchical self-assembly process of the model β-sheet forming peptide KFE8 (Ac-FKFEFKFE-NH₂)_, high-speed atomic force microscopy (HS-AFM) in liquid is used. It is demonstrated that a fast-growing network, based on small fibrillar aggregates, is formed at a solid–liquid interface, while in bulk solution, a distinct, more prolonged nanotube network emerges from intermediate helical ribbons. Moreover, the transformation between these morphologies has been visualized. It is expected that this new in situ and in real-time methodology will set the path for the in-depth unravelling of the dynamics of other peptide-based self-assembled soft materials, as well as gaining advanced insights into the formation of fibers involved in protein misfolding diseases.     

Wireless-SpaceWire bridge for intrasatellite transmissions

The scope of this paper is to present the proof-of-concept and functional verification of a Wireless-SpaceWire bridge (High-Throughput Wireless-SpaceWire Bridge for Intra-Satellite Transmissions [HiSAT] bridge) designed to replace the wired SpaceWire (SpW) connections for intraspacecraft communications. To provide proper data handling and conversion, the proposed solution implements two main components: (1) the SpW Converter, which provides the SpW interface, and (2) the Wireless Converter, which provides the multiantenna radio frequency (RF) front-end. High-end research infrastructure is used in the solution implementation. STAR-Dundee SpW products emulate real spacecraft instrumentation and implement the SpW links and interfaces. Xilinx FPGA ZCU102 boards are used for the implementation of the hardware/software communication stack of the SpW Converter. A comprehensive National Instruments USRP Software Defined Radio platform is used to implement the Wireless Converter. End-to-end laboratory tests are run to evaluate the performance of the proposed solution in terms of average end-to-end delay, average data rate, and packet success rate and to assess the technology readiness. The results demonstrate that the HiSAT bridge is TRL4 and that the technological approach (i.e., using FPGAs and OFDM transmissions) can successfully replace an on-board intraspacecraft SpW link.     

Advanced proof testing for structural ceramics

Proof testing is used to remove weak ceramic components from a manufactured batch in turn truncating the lower end of the strength-failure probability distribution. With proof testing, components are subjected to stresses comparable to those observed during service load histories resulting in the remaining ones having assured minimum reliabilities. The degree to which the reliability of the remaining parts is assured depends on the proof test protocol, which includes multiple variables such as stress level, realistic sampling of flaws, complex geometries, multiaxial stresses, transient loading histories, time-dependent damage due to slow crack growth and/or fatigue, and change in material behavior due to temperature and/or environmental conditions. This paper advances the early work done on proof test theory, which was limited to simple stress states, to include general stress and material states. The theory introduced in this paper takes into account practical conditions often encountered in industrial applications. This advanced proof test theory was coded into the CARES/Life code (Ceramics Analysis and Reliability Evaluation of Structures/Life). Examples are provided to demonstrate the theory.