Stiffness alterations of single cells induced by UV in the presence of nanoTiO2

Nanocrystalline titanium dioxide (nanoTiO2) has been reported to generate reactive oxygen species (ROS) under UV illumination. In our studies, changes in mechanical properties of human skin fibroblasts, exposed to the oxidative stress induced in the presence of nanoTiO2 and UV light, were studied using atomic force microscopy (AFM). The exposure of cells to the action of ROS was performed at low TiO2 concentration (4 microg/mL) and under illumination with low-intensity UVA (8 and 20 mW/cm2) or UVC (0.1 mW/ cm2). AFM measurements of the cell stiffness were carried out immediately after exposure of cells to the oxidative stress. The data suggest that under illumination with low-intensity UVA nanoTiO2 generates ROS, which, in turn, damage cellular and subcellular structures. This process was detected by AFM as a marked drop in the cellular stiffness of ca. 30-75%, which occurred rapidly, in the time frame of 1 min. The photo-oxidative stress inducing the decrease of cell stiffness was cancelled in the presence of a well-established antioxidant, beta-carotene. The results highlight the sensitivity of AFM to detect early changes in mechanical properties of cells exposed to oxidative stress.     

Effect of processing for saponin removal on fungal contamination of quinoa seeds (Chenopodium quinoa Willd.)

Incidence of fungal contamination of quinoa seeds from three locations (Salar de Uyuni, Bolivia; Salta and Tucumán provinces, Argentina) was analyzed in samples with and without treatment to remove saponins (wet method). In processed samples, the percentage of infection was reduced. Distribution of the different fungal genera was not homogeneous in the three locations (p<0.05), although Penicillium and Aspergillus were the most prevalent contaminants, regardless the geographic origin of the samples. Other genera, such as Eurotium, Fusarium, Phoma, Ulocladium, Mucor and Rhizopus were less frequently isolated. Absidia, Alternaria, Cladosporium, Dreschlera, Epicoccum and Monascus were sporadically encountered. Significant differences (p<0.05) in the distribution of fungal genera in samples with and without saponins from each location were observed. In all cases, processing caused a decrease of Aspergillus incidence, while increased the proportion of Penicillium, Eurotium, Mucor and Rhizopus indicating that these genera were part of the internal mycota. A. flavus and A. niger were the dominating species of genus Aspergillus. A similar pattern of prevalent Penicillium species was observed in samples with and without saponins, since P. aurantiogriseum, P.chrysogenum, P. citrinum and P. crustosum were always present in high number, although their relative density was variable according to the geographic origin of samples. Mycotoxin-producing ability of most representative species was also determined. Toxigenic strains of A. flavus (aflatoxins and cyclopiazonic acid), A. parasiticus (aflatoxins), P. citrinum (citrinin) and P. griseofulvum (cyclopiazonic acid) were found. None of the A. niger isolates was ochratoxin A producer. The above mentioned mycotoxins were not detected in the samples analyzed.     

A Kinetic Study on the Heat-Induced Changes of Whey Proteins Concentrate at Two pH Values

Whey protein concentrate (WPC) is used as food ingredients due to their commercially important functional properties. The effects of heat treatment on the components of milk are very important for the final product character, since they undergo modifications that affect sensorial and nutritional quality of milk. The heat-induced changes on dispersions of whey proteins concentrate were monitored by measurement of thiol availability, protein solubility, and turbidity at pH 6.6 and 7.5. The fractional conversion model was used to quantitatively describe the effect of different temperature–time combination on denaturation mechanism. The results demonstrate that heat-induced changes of WPC greatly influence their solubility, expressed as degree of denaturation at pH 4.6 and were related to the heating conditions. The denaturation mechanism involved a number of consecutive conformational changes in the molecules. A curvature in Arrhenius plots was observed around 75 °C, indicating changes in the reaction mechanism. The deflection of Arrhenius plot reflects the generally accepted two-step denaturation/aggregation process of whey proteins.     

Crossing textual and visual content in different application scenarios

This paper deals with multimedia information access. We propose two new approaches for hybrid text-image information processing that can be straightforwardly generalized to the more general multimodal scenario. Both approaches fall in the trans-media pseudo-relevance feedback category. Our first method proposes using a mixture model of the aggregate components, considering them as a single relevance concept. In our second approach, we define trans-media similarities as an aggregation of monomodal similarities between the elements of the aggregate and the new multimodal object. We also introduce the monomodal similarity measures for text and images that serve as basic components for both proposed trans-media similarities. We show how one can frame a large variety of problem in order to address them with the proposed techniques: image annotation or captioning, text illustration and multimedia retrieval and clustering. Finally, we present how these methods can be integrated in two applications: a travel blog assistant system and a tool for browsing the Wikipedia taking into account the multimedia nature of its content.

Hydrothermally treated chitosan spontaneously forms water-soluble spherical particles stable at a wide pH range

The authors report the spontaneous formation of water-soluble chitosan-tartaric acid (CS-TA) spherical particles. Particles are formed by heating chitosan in the presence of tartaric acid under hydrothermal conditions. Tartaric acid serves as an ionic cross-linker, a depolymerizing agent, and a particle stabilizer in aqueous phase. The CS-TA particles exhibit superior colloidal stability at a wide pH range due to their surface charge tunability, which is due to the colocalization of surface hydroxyl, amine, and carboxyl groups. At physiological pH condition, particles have zwitterionic structure as determined by the zeta potential measurements. Still, CS-TA maintains colloidal stability at neutral pH due to the abundance of surface hydroxyl groups. As a proof-of-concept study, the CS-TA particles were labeled with a model insoluble cargo (fluorescein isothiocyanate [FITC]) to demonstrate their capacity for solubilizing hydrophobic drugs. The CS-TA/FITC conjugates were found to remain well dispersed at neutral pH, while maintaining FITC fluorescence properties.     

Palm Oil-Rich Diet Affects Murine Liver Proteome and S-Palmitoylome

Palmitic acid (C16:0) is the most abundant saturated fatty acid in animals serving as a substrate in synthesis and β-oxidation of other lipids, and in the modification of proteins called palmitoylation. The influence of dietary palmitic acid on protein S-palmitoylation remains largely unknown. In this study we performed high-throughput proteomic analyses of a membrane-enriched fraction of murine liver to examine the influence of a palm oil-rich diet (HPD) on S-palmitoylation of proteins. HPD feeding for 4 weeks led to an accumulation of C16:0 and C18:1 fatty acids in livers which disappeared after 12-week feeding, in contrast to an accumulation of C16:0 in peritoneal macrophages. Parallel proteomic studies revealed that HPD feeding induced a sequence of changes of the level and/or S-palmitoylation of diverse liver proteins involved in fatty acid, cholesterol and amino acid metabolism, hemostasis, and neutrophil degranulation. The HPD diet did not lead to liver damage, however, it caused progressing obesity, hypercholesterolemia and hyperglycemia. We conclude that the relatively mild negative impact of such diet on liver functioning can be attributed to a lower bioavailability of palm oil-derived C16:0 vs. that of C18:1 and the efficiency of mechanisms preventing liver injury, possibly including dynamic protein S-palmitoylation.     

New,Non‐quinone Fluorogeldanamycin Derivatives Strongly Inhibit Hsp90

Streptomyces hygroscopicus is a natural producer of geldanamycin. Mutasynthetic supplementation of an AHBA‐blocked mutant with all possible monofluoro 3‐aminobenzoic acids provided new fluorogeldanamycins. These showed strong antiproliferative activity and inhibitory effects on human heat shock protein Hsp90. Binding to Hsp90 in the low nanomolar range was determined from molecular modelling, AFM analysis and by calorimetric studies.     

Recycling polystyrene into fuels by means of FCC: performance of various acidic catalysts

In accordance with the option of recycling plastics into fuels by dissolving them in standard feedstocks for the process of catalytic cracking of hydrocarbons, FCC, various acidic catalysts (zeolites ZSM-5, mordenite, Y, and a sulfur-promoted zirconia) were tested in the conversion of polystyrene dissolved into inert benzene at 550°C in a fluidized-bed batch reactor. Experiments were performed with very short contact times of up to 12 s. Main products were in the gasoline range, including benzene, toluene, ethylbenzene, styrene, and minor amounts of C_9–12 aromatics and light C₅₋ compounds. Coke was always produced in very significant amounts. All the products can be justified with basis on the properties of each catalyst and the various possible catalytic reaction pathways: cracking after protolytic attack on the polymer fragments, styrene oligomerization and subsequent cracking, or hydrogen transfer to styrene. Styrene would be mainly produced in this system from thermal cracking of the polymer as the initial step. If present, shape selectivity effects due to catalyst structure can influence significantly the prevalence of the various reactions, because they would interfere with those undergoing bulky transition states, like styrene oligomerization or hydrogen transfer. Even though sulfur-promoted zirconia is highly acidic, the low proportion of Brønsted-type acid sites does not allow the occurrence of secondary styrene reactions. It was shown that most favorable product distributions (higher yields of desirable products) are obtained on equilibrium commercial FCC catalysts.