Antitumor Effects of Vitamin D Analogs on Hamster and Mouse Melanoma Cell Lines in Relation to Melanin Pigmentation

Deregulated melanogenesis is involved in melanomagenesis and melanoma progression and resistance to therapy. Vitamin D analogs have anti-melanoma activity. While the hypercalcaemic effect of the active form of Vitamin D (1,25(OH)₂D₃) limits its therapeutic use, novel Vitamin D analogs with a modified side chain demonstrate low calcaemic activity. We therefore examined the effect of secosteroidal analogs, both classic (1,25(OH)₂D₃ and 25(OH)D₃), and novel relatively non-calcemic ones (20(OH)D₃, calcipotriol, 21(OH)pD, pD and 20(OH)pL), on proliferation, colony formation in monolayer and soft-agar, and mRNA and protein expression by melanoma cells. Murine B16-F10 and hamster Bomirski Ab cell lines were shown to be effective models to study how melanogenesis affects anti-melanoma treatment. Novel Vitamin D analogs with a short side-chain and lumisterol-like 20(OH)pL efficiently inhibited rodent melanoma growth. Moderate pigmentation sensitized rodent melanoma cells towards Vitamin D analogs, and altered expression of key genes involved in Vitamin D signaling, which was opposite to the effect on heavily pigmented cells. Interestingly, melanogenesis inhibited ligand-induced Vitamin D receptor translocation and ligand-induced expression of VDR and CYP24A1 genes. These findings indicate that melanogenesis can affect the anti-melanoma activity of Vitamin D analogs in a complex manner.     

Reduction of NO2 stored in a commercial lean NO x trap at low temperatures

Isothermal storage of NO₂ and subsequent reduction with different reducing agents (H₂, CO or H₂ + CO) in a lean NO _x trap catalyst was tested by Temperature Programmed Desorption (TPD) and Temperature Programmed Reduction (TPR) experiments at temperatures representative of automotive “cold-start” conditions (<200 °C) using a commercial NO _x trap catalyst. Results from the TPR experiments revealed that no reduction of stored NO₂ to N₂ was observed at 100–180 °C, and at 200 °C 10% reduction only of NO₂ to N₂ was measured. A special affinity of H₂ to form NH₃ was observed during the reduction of stored NO₂. The formation of NH₃ increases with increasing amount of stored NO₂ and decreases with increasing storage temperature. Direct relation exists between the amount of adsorbed and/or stored NO₂ and the formation of H₂O and NH₃.     

Influence of Ageing, Silver Loading and Type of Reducing Agent on the Lean NO x Reduction Over Ag–Al2O3 Catalysts

The influence of ageing temperature, silver loading and type of reducing agent on the lean NO _x reduction over silver–alumina catalysts was investigated with n-octane and bio-diesel (NExBTL) as reducing agent. The catalysts (2 and 6 wt% Ag–Al₂O₃) were prepared with a sol–gel method including freeze drying and the evaluation of NO _x reduction and aging were performed using a synthetic gas-flow reactor. The results indicate a relatively high NO _x reduction for both reducing agents. The hydrothermally treated 6 wt% Ag–Al₂O₃ sample displays a maximum NO _x reduction of 78 % at 350 °C for n-octane as reductant and the corresponding value for NExBTL is 60 %. Furthermore, the catalysts show high durability and an increase in activity for NO _x reduction after ageing at temperatures up to 650 °C, with n-octane as reducing agent.     

Dynamic stress relaxation of thermoplastic elastomeric biomaterials

In this paper we present the results of comparative dynamic stress relaxation studies performed with poly(styrene-b-isobutylene-b-styrene) (SIBS), polyurethane (PU) and polyester (PED) biomaterials in air and simulated body fluid (SBF) at 24 °C and 37 °C. SIBS showed the highest value of relieved stress under constant strain (24.1% after 100,000 cycles in air) with PED and PU having similar relative change (12.2% and 10.5%). In spite of its softness (Shore A 56 vs. 80), the dynamic modulus (E_dyn) and stiffness of SIBS were in between PED and PU. The behavior of the materials was correlated to their structure: SIBS is an amorphous block copolymer with a long elastomer midblock, while PU and PED are semicrystalline segmented copolymers with much shorter soft blocks, and hydrogen bonding. SIBS and PED were relatively insensitive to SBF and temperature changes, while PU experienced the largest changes in physical properties in vitro (simulated body fluid, 37 °C).     

Gas quenching probe and field measurements of gaseous cadmium in a 12-MWth circulating fluidised bed combustion boiler

A probe-based technique for measurement of gas phase metal species in flue gas at high temperatures has been developed. This paper deals with work carried out to test and evaluate the technique through field measurements of cadmium species during co-combustion of sewage sludge and other solid fuels in a circulating fluidised bed combustion boiler. During the measurements of vaporous cadmium forms, solid fly ash samples were also collected at the measurement positions. Chemical composition data from these fly ash samples were used to discuss the influence that the fly ash filter cake built up on the probe tip can have on the measurements. Additionally, the solid samples were examined by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques to have a better insight into the problem. Using the data from the field measurements and/or from the integrated measurements and weighing devices of the boiler the mass balance of cadmium from the combustion process was calculated by different methods. The calculation results were fairly consistent. In one method, data from the field measurements was used. This method gave the mass balance for cadmium in the process Cd_out/Cd_in=113.6%, which was a very good result considering that it involved the analysis of trace amount of metals in full-scale measurements.     

Nanocomposite Elastomeric Biomaterials for Myocardial Tissue Engineering Using Embryonic Stem Cell‐derived Cardiomyocytes

Regeneration or repair of the damaged myocardium requires different strategies including engineered constructs for more efficient cell delivery. This study was undertaken to examine the potential of a new nanostructured elastomer to deliver embryonic stem cell‐derived cardiomyocytes (ESC‐CM) to an infarcted area of the myocardium. Engineered materials were biocompatible, mechanically stable, and elastomeric nanocomposites serving as substrates for delivery of ESC‐CM and as a left ventricular support device in myocardial regeneration strategies. Materials investigated were soft and strong poly(aliphatic/aromatic‐ester) multiblock thermoplastic elastomers with poly(ethylene terephthalate) (PET) hard segments and dimerized fatty acid, i.e., dilinoleic acid (DLA) soft segments, respectively, with and without addition of 0.2 wt% TiO₂ nanoparticles to form nanocomposites. The PET/DLA‐TiO₂ nanocomposite exhibited over 8 MPa tensile strength and 900% elongation at break. Addition of TiO₂ nanoparticles significantly altered surface roughness and enhanced adhesion and spreading of ESC‐CM derived from mouse and human embryonic stem cells. The newly developed materials did not affect the functional activity of spontaneously beating hESC‐CM, as demonstrated by unaltered rate of their beating, and the cells continued to demonstrate contractile activity on the materials for more than two months in culture (the longest time tested). Quantitative proliferation and survival assays using fibroblasts confirmed the ability of the new materials to support cells as well as or better than the present commercial‐type thermoplastic elastomer analog. The results indicate that PET/DLA and PET/DLA‐TiO₂ are promising candidates for the manufacture of engineered patches to deliver ESC‐CMs.     

Influence of TiO2 Nanoparticles Incorporated into Elastomeric Polyesters on their Biocompatibility In Vitro and In Vivo

Fibroblasts proliferation and apoptosis as well as tissue response after implantation of elastomers containing nanocrystalline TiO₂ were investigated in the present in vitro and in vivo study. Materials investigated were soft poly(aliphatic/aromatic‐ester) multiblock thermoplastic elastomers with poly(ethylene terephthalate) (PET) hard segments and dimerized linoleic acid (DLA) soft segments, respectively, containing 0.2 wt% TiO₂ nanoparticles. An investigation of the influence of TiO₂ nanoparticles incorporated into polymeric material on in vitro biocompatibility revealed enhanced cell proliferation and diminished number of necrotic and apoptotic cells as compared to nanoparticles‐free polymer. Implantation tests indicated that the observed tissue changes were similar to those observed with medical‐grade silicone elastomer, no evidence of contact necrosis being observed. The unchanged morphology of rat liver hepatocytes and the lack of parenchymal necrosis also indicated that exposure to the material containing TiO₂ nanoparticles, did not cause any cytotoxic reactions. The present study, thus, showed that elastomeric polyester containing TiO₂ nanoparticles are interesting biomimetic constructs for improved tissue regeneration.     

The Effect of a Changing Lean Gas Composition on the Ability of NO2 Formation and NOx Reduction over Supported Pt Catalysts

Three model catalysts (Pt/Al₂O₃, Pt/TiO₂, Pt/V₂O₅/TiO₂) were examined in regard to their NO₂ formation ability under a changing lean gas composition. The results show that the NO to NO₂ oxidation function as well as the NO _x reduction under lean gas conditions is affected by a change in the lean gas atmosphere. The NO oxidation activity also decreased with time, for Pt/Al₂O₃ and Pt/TiO₂, and a possible explanation may be platinum oxide formation. This deactivation was not observed for Pt/V₂O₅/TiO₂.     

The effect of fibre sizing and compatibilizer of polypropylene/poly(butylene terephthalate) blends on the mechanical and interphase properties of basalt fibre reinforced composites

The effect of basalt fibre sizing on the mechanical and interphase properties of fibre‐reinforced composites was studied. Two different chemical preparations of the fibre surface (PBT‐compliant and PP‐compliant) were used. The polymer matrix was prepared from polypropylene/poly(butylene terephthalate) (PP/PBT) immiscible polymer blend and the effect of different compatibilizers on the composite properties was evaluated. SEM hints at improved fibre adhesion to the polymer matrix when a PP‐compliant sizing is applied. SEM also reveals improved compatibilization effects when block copolymer instead of multiblock copolymer is used for the PP/PBT blend preparation. The pull‐out test was applied to quantitatively evaluate the interface adhesion between the fibres and matrices. It showed a high value of the interfacial shear strength between basalt fibres modified with PP‐compliant sizing and polymer blend compatibilized by block copolymer, thus confirming good adhesion. One possible explanation of such good mechanical properties can be related to the chemical interactions between functional groups, mainly maleic anhydride on basalt fibres and the polyolefin component (PP) of the polymer matrix. © 2017 Society of Chemical Industry