Gene subset selection using an iterative approach based on genetic algorithms

Microarray data are expected to be useful for cancer classification. However, the process of gene selection for the classification contains a major problem due to properties of the data such as the small number of samples compared with the huge number of genes (higher-dimensional data), irrelevant genes, and noisy data. Hence, this article aims to select a near-optimal (small) subset of informative genes that is most relevant for the cancer classification. To achieve this aim, an iterative approach based on genetic algorithms has been proposed. Experimental results show that the performance of the proposed approach is superior to other previous related work, as well as to four methods tried in this work. In addition, a list of informative genes in the best gene subsets is also presented for biological usage.     

Investigation of chitosan‐g‐PEG grafted nanoparticles as a half‐life enhancer carrier for tissue plasminogen activator delivery

Tissue plasminogen activator (tPA) a thrombolytic agent is commonly used for digesting the blood clot. tPA half‐life is low (4–6 min) and its administration needs a prolonged continuous infusion. Improving tPA half‐life could reduce enzyme dosage and enhance patient compliance. Nano‐carries could be used as delivery systems for the protection of enzymes physically, enhancing half‐life and increasing the stability of them. In this study, chitosan (CS) and polyethylene glycol (PEG) were used for the preparation of CS‐g‐PEG/tPA nanoparticles (NPs) via the ion gelation method. Particles’ size and loading capacity were optimised by central composite design. Then, NPs cytotoxicity, release profile, enzyme activity and in vivo half‐life and coagulation time were investigated. The results showed that NPs does not have significant cytotoxicity. Release study revealed that a burst effect happened in the first 5 min and resulted in releasing 30% of tPA. Loading tPA in NPs could decrease 25% of its activity but the half‐life of it increases in comparison to free tPA in vivo. Also, blood coagulation time has significantly affected (p ‐value = 0.041) by encapsulated tPA in comparison to free tPA. So, CS‐g‐PEG/tPA could increase enzyme half‐life during the time and could be used as a non‐toxic candidate delivery system for tPA.Inspec keywords: drug delivery systems, nanofabrication, drugs, nanomedicine, coagulation, biomedical materials, cellular biophysics, enzymes, biochemistry, toxicology, molecular biophysics, biological tissues, blood, nanoparticles, polymersOther keywords: chitosan‐g‐PEG grafted nanoparticles, half‐life enhancer carrier, tissue plasminogen activator delivery, tPA half‐life, prolonged continuous infusion, enzyme dosage, polyethylene glycol, cytotoxicity, enzyme activity, encapsulated tPA, enzyme half‐life, blood coagulation, time 5.0 min     

Social factors and compulsory detention of psychiatric patients in the U.K. The role of the approved social worker in the 1983 Mental Health Act

Low-density lipoprotein (LDL) is known to be a mitogenic factor for vascular smooth muscle cells (VSMCs), fibroblasts, and endothelial cells. In the current study, we describe possible intracellular mechanisms by which LDL elicits its mitogenic effects. Stimulation of VSMCs with LDL resulted in a pertussis-toxin (PTX)-sensitive stimulation of the 44-kDa mitogen-activated protein (MAP) kinase (p44(mapk)) and 42-kDa MAP kinase (p42(mapk)) isoforms as well as in a PTX-sensitive increase in intracellular free Ca2+ concentration ([Ca2+]i). Binding of the LDL-induced increase in [Ca2+]i to the intracellular Ca2+ chelator bis(2-amino-5-methylphenoxy)ethane-N,N,N',N'-tetraacetic acid tetraacetoxymethyl ester resulted in a 2-fold increase in the phosphorylated p44(mapk) and p42(mapk) isoforms but did not influence the LDL effect of VSMC DNA synthesis. PD 98059, a MAP kinase kinase inhibitor, remarkably attenuated the LDL-induced activation of MAP kinases and DNA synthesis. Treatment of normal human skin fibroblasts and human fibroblasts isolated from patients with familial hypercholesterolemia homozygote class 1 mutations, which are not able to produce the classic LDL receptor, resulted also in a PTX-sensitive increase in cell DNA synthesis and stimulation of the p44(mapk) and p42(mapk) isoforms in both cell types. These results demonstrate that the mitogenic effect of LDL is mediated by a PTX-sensitive Gi-coupled receptor that is independent of its classic receptor and involves activation of MAP kinase isoforms. Furthermore, the mitogenic effect of LDL may be mediated by the activation of the MAP kinase pathway. In contrast, the LDL-induced increase in [Ca2+]i may be implicated in this process only in conjugation with other signaling components.     

Lipase‐catalyzed production of medium‐chain triacylglycerols from palm kernel oil distillate: Optimization using response surface methodology

Optimization of lipase‐catalyzed esterification for the production of medium‐chain triacylglycerols (MCT) from palm kernel oil distillate and glycerol was carried out in order to determine the factors that have significant effects on the reaction system and MCT yield. Novozyme 435 from Candida antarctica lipase was found to have the highest activity at 52.87 ± 0.03 U/g. This lipase also produced the highest MCT yield, which is 56.67%. The effect of different variables on MCT synthesis was studied with a two‐level five‐factor fractional factorial design. The various variables include (1) reaction temperature, (2) enzyme load, (3) molecular sieves concentration, (4) reaction time and (5) molar substrate ratio. Reaction temperature, reaction time and molar substrate ratio strongly affect MCT synthesis (p <0.05). However, enzyme load and molecular sieve concentration did not have a significant (p >0.05) influence on MCT yield. Therefore, the significant variables such as reaction temperature, reaction time and molar substrate ratio were further optimized through central composite rotatable design (CCRD). Comparisons between predicted and experimental values from the CCRD optimization procedures revealed good correlation, implying that the quadric response model satisfactorily expressed the percentage yield of MCT in the lipase‐catalyzed esterification. The optimum MCT yield is 73.3% by using 2 wt‐% enzyme dosage, a molecular sieves concentration of 1 wt‐%, a reaction temperature of 90 °C, a reaction time of 10 h and a molar substrate ratio of 4 : 1 (medium‐chain fatty acid/glycerol). Experiments to confirm the predicted results using the optimal parameters were conducted and an MCT yield of 70.21 ± 0.18% (n = 3) was obtained.     

Proposed Relationship for Proper Shear Strength of Elliptical Damper Based on Its Geometrical Parameters

Vertical link beam as a practical yielding damper is a kind of passive control device which dissipates seismic energy and thus reduces the rate of damage to structures through in-plane shear deformations. Proper stiffness, ductility and significant energy dissipation of these dampers together with their practical advantages justify their widespread experimental and numerical research. In this paper, a total of 42 elliptical dampers (vertical link beams with elliptical cross sections) in various lengths and thicknesses are modeled using the ABAQUS finite element software and finally a design relationship for this damper is presented based on the above mentioned geometrical parameters using pushover analysis. The accuracy of the proposed relationship is studied by applying various layouts of designed dampers on two types of chevron bracings to improve their performance and obtain proper energy dissipation without brace buckling. The equivalent viscous damping ratios of 32–33% obtained for elliptical dampers indicate high increase in energy dissipation capability.     

Synthesis,Structure Characterization and Biological Activity of Co (II), Cu (II), and Zn (II) Complexes with (Z)‐3‐((3‐hydroxybenzylidene)amino)pyridin‐1‐ium 4‐(dodecan‐4‐yl)benzenesulfonate Surfactant

(Z)‐3‐((3‐hydroxybenzylidene)amino)pyridin‐1‐ium4‐dodecylbenzenesulfonate anionic surfactant and its cobalt, copper and zinc complexes were synthesized (I, I‐Co, I‐Cu and I‐Zn). The chemical structures of it were characterized by elemental analysis, FTIR, ¹H‐NMR, UV–Vis spectroscopy and atomic adsorption. The effects of the chemical structures of the synthesized anionic surfactant and the type of transition metals on the surface activity are presented in this paper. The thermodynamic parameters show that adsorption and micellization processes are spontaneous. The results of biological activity measurements showed that the synthesized compounds have a great efficiency against gram positive (Bacillus subtilis and Staphylococcus aureus), gram‐ negative bacteria (Pseudomonas aeruginosa and Escherichia coli) and fungi (Candida albicans and Aspergillus niger) as well as the sulfate reducing bacteria (Desulfomonas pigra). The complexation of the anionic surfactant with Co²⁺, Cu²⁺ and Zn²⁺ increase the antimicrobial activity values.     

An innovative approach to electro-oxidation of dopamine on titanium dioxide nanotubes electrode modified by gold particles

Au/TiO₂/Ti electrodes were prepared by galvanic deposition of gold particles from an acidic bath containing KAu(CN)₂ in the presence of a citrate buffer onto TiO₂ nanotubes layer on titanium substrates. Titanium oxide nanotubes were fabricated by anodizing titanium foil in a DMSO fluoride-containing electrolyte. The morphology and surface characteristics of Au/TiO₂/Ti electrodes were investigated using scanning electron microscopy and energy-dispersive X-ray, respectively. The results indicated that gold particles were homogeneously deposited on the surface of TiO₂ nanotubes. The nanotubular TiO₂ layers consist of individual tubes of about 40–80 nm diameters. The electro-catalytic behavior of Au/TiO₂/Ti electrodes for the dopamine electro-oxidation was studied by cyclic voltammetry and differential pulse voltammetry. The results showed that Au/TiO₂/Ti electrodes exhibit a considerably higher electro-catalytic activity toward the oxidation of dopamine. The catalytic oxidation peak current showed a linear dependence on dopamine concentration and a linear calibration curve was obtained in the concentration range of 0.5–2.5 mM of dopamine.     

Flammability and mechanical properties of wood flour‐filled polypropylene composites

Polypropylene (PP) composites filled with wood flour (WF) were prepared with a twin‐screw extruder and an injection‐molding machine. Three types of ecologically friendly flame retardants (FRs) based on ammonium polyphosphate were used to improve the FR properties of the composites. The flame retardancy of the PP/WF composites was characterized with thermogravimetric analysis (TGA), vertical burn testing (UL94‐V), and limiting oxygen index (LOI) measurements. The TGA data showed that all three types of FRs could enhance the thermal stability of the PP/WF/FR systems at high temperatures and effectively increase the char residue formation. The FRs could effectively reduce the flammability of the PP/WF/FR composites by achieving V‐0 UL94‐V classification. The increased LOI also showed that the flammability of the PP/WF/FR composites was reduced with the addition of FRs. The mechanical property study revealed that, with the incorporation of FRs, the tensile strength and flexural strength were decreased, but the tensile and flexural moduli were increased in all cases. The presence of maleic anhydride grafted polypropylene (MAPP) resulted in an improvement of the filler–matrix bonding between the WF/intumescent FR and PP, and this consequently enhanced the overall mechanical properties of the composites. Morphological studies carried out with scanning electron microscopy revealed clear evidence that the adhesion at the interfacial region was enhanced with the addition of MAPP to the PP/WF/FR composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010