Sphingolipid metabolism in colorectal adenomas varies depending on histological architecture of polyps and grade of nuclear dysplasia

Incidence of colorectal cancer (CRC) is growing worldwide. Pathogenetic mechanisms responsible for its onset and progression need further clarification. Colorectal adenomatous polyps are precancerous lesions with malignant potential dependent on histological architecture and grade of nuclear dysplasia. One of the factors conditioning CRC development are abnormalities in sphingolipid metabolism. The aim of this study was to assess the levels of sphingolipids in human colorectal adenomas. The control group (C, n = 12) consisted of patients with no colonic polyps. The examined group consisted of patients with prior diagnosed colonic polyps, qualified to endoscopic polypectomy. This group was further divided due to histological architecture into tubular adenomas group (TA, n = 10), tubulovillous adenomas with low‐grade dysplasia (LGD‐TVA, n = 10), and tubulovillous adenomas group with high‐grade dysplasia (HGD‐TVA, n = 11). In tissue samples, sphingolipd metabolite contents were measured using high performance liquid chromatography (HPLC). In cases of polypoid lesions with low malignancy potential (tubular adenomas), concentration of ceramide, which is characterized by proapoptotic and anti‐proliferative properties, increases compared with control group (p < 0.05), whereas content of sphingosine‐1‐phosphate with anti‐apoptotic and stimulating cellular proliferation properties is reduced in comparison with control group (p < 0.05). On the contrary, in cases of more advanced form of adenomatous polyps (tubulovillous adenomas with high‐grade dysplasia), the ceramide level decreases compared with control group (p < 0.05) while sphingosine‐1‐phosphate concentration is elevated (p < 0.05). We found that concentrations of pro‐apoptotic ceramide are decreased and pro‐proliferative S1P levels are increased in polypoid lesions with high malignancy potential, and it was the opposite in those with low malignancy potential.     

Materials Displaying Neural Growth Factor Gradients and Applications in Neural Differentiation of Embryoid Body Cells

The critical growth factor density required to support neural lineage generation from mouse embryonic stem cells is assessed by constructing a surface density gradient of immobilized nerve growth factor (NGF) from a plasma polymer film base. A chemical surface gradient varying from high hydroxyl group density to high aldehyde group density is prepared through diffusion‐controlled plasma polymerization of two monomers (ethanol and propionaldehyde) under a moving mask. NGF density gradients are then produced by reductive amination with the aldehyde groups on the plasma polymer surface. Mouse embryoid body derived (mEB) cell differentiation on the gradient surface is evaluated by immunofluorescence staining against Nestin. mEB cell density and the percentage of Nestin‐positive cells increase with increasing NGF density up to a critical value corresponding to 52.9 ng cm^?2, above which cell attachment and differentiation do not increase further. This gradient‐based screening approach allows the growth factor surface densities to be optimized for biomaterials intended for cell differentiation or expansion, which is highly relevant to creating efficient manufacture processes for cell therapies.     

The effects of Aphis fabae infestation on the antioxidant response and heavy metal content in field grown Philadelphus coronarius plants

The purpose of this study was to explore a possible relationship between the soil availability of metals and their concentrations in various parts of Philadelphuscoronarius plants. Moreover, the possible impact of an aphid infestation on the contamination and antioxidant response of plants from the urban environment of Kraków and the reference rural area of Zagaje Stradowskie (southern Poland) was analyzed. The contents of the glutathione, proline, non-protein − SH groups, antioxidants, and phosphorous and the levels of guaiacol peroxidase and catalase activity in leaves and shoots either infested or not by the aphid Aphis fabae Scop., were measured. The potential bioavailability of metals (Cd; Cu; Ni; Pb; Zn) in the soil and their concentrations in P. coronarius plants originating from both sites were compared.The antioxidant responses were generally elevated in the plants in the polluted area. Such reactions were additionally changed by aphid infestation. Generally, the concentrations of metals in the HNO₃ and CaCl₂ extractants of the soils from two layers at the 0-20 and 20-40 cm depths from the polluted area were higher than in those from the reference area. Such differences were found for nickel and lead (in all examined extractants), zinc (in soil extractants from the layer at 20-40 cm) and cadmium (in HNO₃ extractants). Significant positive relationships between the lead concentrations in the soil and in the plants were found. In the parts of plants from the polluted area, higher concentrations of Pb and Zn (leaves and shoots) and Cd (shoots) were recorded. The shoots and leaves of plants infested with aphids had higher concentrations of Zn but lower Pb. Moreover, their leaves had higher contaminations of Cu and Ni. In conclusion, aphids affected not only the antioxidant response of the plants but also their contamination with metals, especially contamination of the leaves.     

Biodegradation of plastified starch obtained by corotation twin‐screw extrusion

The potato starch has been subjected to plastification with glycerol using twin‐screw extruder in different conditions. The structure of obtained samples has been determined by Fourier transform infrared spectroscopy with attenuated total reflectance methods. The average molecular weights by chromatographic method and solubility in water have also been determined. Next, the susceptibility of all samples to activity of microorganisms such as bacteria, fungi, and actinomycetes has been checked. It has been stated that increasing rotation speed of extruder screws causes the degradation of starch slightly, influencing the later bio‐decomposition. The actinomycetes are the most effective in this process. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Subsampling inference for the autocovariances and autocorrelations of long‐memory heavy‐ tailed linear time series

We provide a self‐normalization for the sample autocovariances and autocorrelations of a linear, long‐memory time series with innovations that have either finite fourth moment or are heavy‐tailed with tail index 2 < α < 4. In the asymptotic distribution of the sample autocovariance there are three rates of convergence that depend on the interplay between the memory parameter d and α, and which consequently lead to three different limit distributions; for the sample autocorrelation the limit distribution only depends on d. We introduce a self‐normalized sample autocovariance statistic, which is computable without knowledge of α or d (or their relationship), and which converges to a non‐degenerate distribution. We also treat self‐normalization of the autocorrelations. The sampling distributions can then be approximated non‐parametrically by subsampling, as the corresponding asymptotic distribution is still parameter‐dependent. The subsampling‐based confidence intervals for the process autocovariances and autocorrelations are shown to have satisfactory empirical coverage rates in a simulation study. The impact of subsampling block size on the coverage is assessed. The methodology is further applied to the log‐squared returns of Merck stock.     

The influence of calcination parameters on free calcium oxide content in natural hydroxyapatite

Effect of calcining temperature and time on the content of free CaO in hydroxyapatite of natural origin is presented. Hydroxyapatite was obtained from pork bones in the course of a three-stage process: hydrolysis with the application of lactic acid, pre-calcination at 600 °C and main calcination stage within the temperature range of 750-950 °C. Calcination was conducted in an electrically heated stationary chamber oven in air atmosphere and in a laboratory scale rotary kiln equipped with a gas burner. The FT-IR spectra confirmed that all organic substances were removed during the calcination process. An increase in free calcium oxide content in hydroxyapatite from 0.003% to 0.023% was caused by the increase of calcining temperature from 750 °C to 950 °C respectively. Calcining time at 950 °C gave a distinct impact upon free CaO content ranging from 0.014% (2 h) to 0.023% (3 h). Hydroxyapatite calcined in the rotary kiln contained the lowest amount of free calcium oxide: 0.002% (750 °C) and 0.003% (950 °C). A method of neutralizing of free calcium oxide, present in calcined hydroxyapatite powders of natural origin, through CaO transformation into hydroxyapatite by application of diluted thermic phosphoric acid has been developed.     

Nanostructured systems based on SBS epoxidized triblock copolymers and well-dispersed alumina/epoxy matrix composites

In the present research, the effect of addition of (1 wt.% and 3 wt.%) alumina nanoparticles (Al₂O₃) to epoxy modified by poly(styrene-b-butadiene-b-styrene) (SBS) epoxidized triblock copolymer was studied. The microstructure of final hybrid composites was studied with atomic force microscopy (AFM). Composites showed homogeneously dispersed Al₂O₃ nanoparticles in the epoxy matrix containing polystyrene (PS) microphase separated nanodomains. Dynamic mechanical analyses (DMA), flexural and fracture toughness investigations were carried out. The glass transition temperature of epoxy matrix has been retained unchanged by the addition of Al₂O₃ nanoparticles. The nanostructured epoxy systems based on SBS epoxidized triblock copolymer and well-dispersed Al₂O₃ nanoparticles allowed an increase in fracture toughness maintaining the transparency and stiffness of neat epoxy.     

Surface characterization and cytocompatibility evaluation of silanized magnesium alloy AZ91 for biomedical applications

Mg alloys with high Al contents have superior corrosion resistance in aqueous environments, but poor cytocompatibility compared to that of pure Mg. We have silanized the cast AZ91 alloy to improve its cytocompatibility using five different silanes: ethyltriethoxysilane (S1), 3-aminopropyltriethoxysilane (S2), 3-isocyanatopyltriethoxysilane (S3), phenyltriethoxysilane (S4) and octadecyltriethoxysilane (S5). The surface hydrophilicity/hydrophobicity was evaluated by water contact angle measurements. X-ray photoelectron analysis was performed to investigate the changes in surface states and chemical composition. All silane reagents increased adsorption of the albumin to the modified surface. In vitro cytocompatibility evaluation revealed that silanization improved cell growth on AZ91 modified by silane S1. Measurement of the concentration of Mg²⁺ ions released during the cell culture indicated that silanization does not affect substrate degradation.     

Pt–Co cathode electrocatalyst behaviour viewed by in situ XAFS fuel cell measurements

The paper presents a preliminary structural investigation of the 20% Pt–Co (1:1) alloy on Vulcan XC-72 catalyst using X-ray absorption spectroscopy (XAS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). XAS results have been obtained ex situ and in situ using a specially optimized for XAS measurement fuel cell (down to 6 keV). The results are compared with those obtained for pure Pt catalyst on the same carbon support under the same working conditions.     

Kinetics of spouted-bed drying of barley: Diffusivities for sphere and ellipsoid

A study was performed to observe the drying kinetics of barley dried in a spouted-bed drier and to study the influence of the shape of a kernel assumed in the model on the estimated value of effective moisture diffusivity. Significant differences were observed in the moisture diffusivities of barley between temperatures applied and it ranged from 1.39 × 10⁻¹⁰ m²/s at 33 °C for ellipsoidal geometry to 5.31 × 10⁻¹⁰ m²/s at 56 °C for sphere. The model used has great potential and it is accurate and efficient to simulate moisture diffusion phenomena during drying of ellipsoidal-shaped solids, including spheres as a limit case. The results proved that using the proper geometry of a solid if of a fundamental importance for the purpose of determination its moisture diffusivity. It was also shown that using spherical geometry for modeling drying processes of grain is faulty if high accuracy of the results is expected.