Structural and electrical properties of paper-polyaniline composite

Conducting polymers have generated a great deal of interest because of their physical and chemical properties as well as their potential application in industry particularly in packaging applications. However one of short comings of most conducting polymer is that they are often formed as intractable films that are difficult to process. To overcome this problem we have incorporated conducting polymer, namely polyaniline into sheets of paper in order to create new composite material which combine the universal properties of paper product with the chemical and electrically conducting properties of the conducting polymer. Paper conducting polymer composite have been prepared by polymerizing aniline directly onto the paper sheet using ammonium peroxydisulfate (APS) as an oxidant at different temperatures. The prepared composite was characterized by FT-IR and SEM. The thermo-oxidative degradation was studied by thermo gravimetric analysis (TGA); electrical conductivities measurements of the composites were significantly increased over those of the precursor paper.     

Rapid synthesis of antimicrobial paper under microwave irradiation

The silver-nanoparticle (AgNP) containing paper was successfully prepared. The AgNP is deposited by the in situ reduction of silver nitrate on the acrylamide grafted bagasse paper sheets in the presence of citrate molecules as stabilizing agent. In the present paper, grafting of acrylamide onto bagasse paper sheets using potassium persulfate was carried out under the influence of microwave radiations (MWR). The modified paper sheets were characterized by Fourier transform infrared spectroscopy (FTIR), UV-spectroscopy, and scanning electron microscopy (SEM). Antimicrobial activities of the prepared paper sheets were also investigated against G+ve bacterium Staphylococcus aureus, G-ve bacterium Pseudomomas aeruginosa, and yeast Candida albicans, which are model microorganisms for testing bactericidal properties. The AgNP containing paper sheets exhibited antibacterial activity.     

Kinetic and analytical study of the photo-induced degradation of monuron by nitrates and nitrites under irradiation or in the dark

The photo-induced transformation of monuron (3-(4-chlorophenyl)-1,1 dimethylurea) was investigated in an aqueous solution containing nitrates and nitrites at 310 nm and 365 nm, respectively. In both NO(3)(-) and NO(2)(-) conditions, the degradation of monuron followed pseudo-first order kinetics. The intermediate products were identified by GC-MS, and the nitration, hydroxylation and coupling reactions were determined. In addition, the oxidation of the N-terminus group, the substitution of chlorine by ˙OH and the nitration by ˙NO(2) radical onto the phenyl ring were observed. The photo-induced transformation of monuron was studied under variable conditions of pH, inducer concentration, substrate concentration, humic acids, oxygen content and salts used as hydroxyl radical scavengers. The photodegradation rates were strongly influenced by all the above parameters. The degradation of monuron was also studied in the dark and in the presence of NO(2)(-) as well as in an aqueous solution with the addition of hydrogen peroxide.     

Prevalence and Risk Factors Associated with Entamoeba histolytica/dispar/moshkovskii Infection among Three Orang Asli Ethnic Groups in Malaysia

Background

Entamoeba histolytica/Entamoeba dispar/Entamoeba moshkovskii infection is still prevalent in rural Malaysia especially among Orang Asli communities. Currently, information on prevalence of this infection among different ethnic groups of Orang Asli is unavailable in Malaysia. To contribute to a better comprehension of the epidemiology of this infection, a cross-sectional study aimed at providing the first documented data on the prevalence and risk factors associated with E. histolytica/E. dispar/E. moshkovskii infection was carried out among three Orang Asli ethnic groups (Proto-Malay, Negrito, and Senoi) in selected villages in Negeri Sembilan, Perak, and Pahang states, Malaysia.

Methods/Findings

Faecal samples were examined by formalin-ether sedimentation and trichrome staining techniques. Of 500 individuals, 8.7% (13/150) of Proto-Malay, 29.5% (41/139) of Negrito, and 18.5% (39/211) of Senoi were positive for E. histolytica/E. dispar/E. moshkovskii, respectively. The prevalence of this infection showed an age-dependency relationship, with higher rates observed among those aged less than 15 years in all ethnic groups studied. Multivariate analysis confirmed that not washing hands after playing with soils or gardening and presence of other family members infected with E. histolytica/E. dispar/E. moshkovskii were significant risk factors of infection among all ethnic groups. However, eating with hands, the consumption of raw vegetables, and close contact with domestic animals were identified as significant risk factors in Senoi.

Conclusions

Essentially, the findings highlighted that E. histolytica/E. dispar/E. moshkovskii parasites are still prevalent in Malaysia. Further studies using molecular approaches to distinguish the morphologically identical species of pathogenic, E. histolytica from the non-pathogenic, E. dispar and E. moshkovskii are needed. The establishment of such data will be beneficial for the public health authorities in the planning and implementation of specific prevention and control strategies of this infection in different Orang Asli ethnic groups in Malaysia.     

Influence of a non-NK complex region of chromosome 6 on CD4+ invariant NK T cell homeostasis

The number and function of immunoregulatory invariant NKT (iNKT) cells are genetically controlled. A defect of iNKT cell ontogeny and function has been implicated as one causal factor of NOD mouse susceptibility to type 1 diabetes. Other factors of diabetes susceptibility, such as a decrease of regulatory T cell function or an increase in TLR1 expression, are corrected in diabetes-resistant Idd6 NOD.C3H 6.VIII congenic mice. Thus, we surmised that the iNKT cell defects found in NOD mice may also be rescued in congenic mice. Unexpectedly, we found, in both the thymus and the periphery, a 50% reduction in iNKT cell number in NOD.C3H 6.VIII mice as compared with NOD mice. This reduction only affected CD4(+) iNKT cells, and left the double negative iNKT cells unchanged. In parallel, the production of IL-4 and IFN-gamma following alpha-GalCer stimulation was proportionally reduced. Using three subcongenic strains, we have narrowed down the region controlling iNKT development within Idd6 (5.8 Mb) to Idd6.2 region (2.5 Mb). Idd6 region had no effect on NK cell number and in vivo cytotoxic activity. These results indicate that the role of iNKT cells in diabetes development is equivocal and more complex than initially considered. In addition, they bring strong evidence that the regulation of CD4(+) iNKT cell production is independent from that of DN iNKT cells, and involves genes of the Idd6 locus.     

Toxicity assessment of the puffer fish Lagocephalus lagocephalus from the Tunisian coast

This study was undertaken to assess the risk of poisoning due to consumption of the puffer fish Lagocephalus lagocephalus collected along the Tunisian coast. Wistar rats were daily intraperitoneally injected, for 10 days, with acidic extracts of liver or flesh (muscles + skin) of L. lagocephalus. Control rats received injections of NaCl (0.9%). No mortality and no evident signs of neurotoxicity were recorded in treated rats. Conversely, treatment led to: (1) diarrhoea and body and organ (liver, kidney) weights loss; (2) oxidative stress evidenced by an increase in lipid peroxidation (TBARS) and conversely a decrease in antioxidant enzyme activities (SOD, catalase, GSH-Px) in tissues (blood cells, liver, kidneys); (3) a decrease in alanine aminotransferase (ALT) and alkaline phosphatase (ALP) activities in blood plasma.     

HIV-1 Tat inhibits NGF-induced Egr-1 transcriptional activity and consequent p35 expression in neural cells

Infection with HIV-1 causes degeneration of neurons leading to motor and cognitive dysfunction in AIDS patients. One of the key viral regulatory proteins, Tat, which is released by infected cells, can be taken up by various uninfected cells including neurons and by dysregulating several biological events induces cell injury and death. In earlier studies, we demonstrated that treatment of neuronal cells with Tat affects the nerve growth factor (NGF) signaling pathway involving MAPK/ERK. Here we demonstrate that a decrease in the level of Egr-1, one of the targets for MAPK, by Tat has a negative impact on the level of p35 expression in NGF-treated neural cells. Further, we demonstrate a reduced level of Egr-1 association with the p35 promoter sequence in NGF-treated cells expressing Tat. As p35, by associating with Cdk5, phosphorylates several neuronal proteins including neurofilaments and plays a role in neuronal differentiation and survival, we examined kinase activity of p35 complexes obtained from cells expressing Tat. Results from H1 kinase assays showed reduced activity of the p35 complex from Tat-expressing cells in comparison to that from control cells. Accordingly, the level of phosphorylated neurofilaments was diminished in Tat-expressing cells. Similarly, treatment of PC12 cells with Tat protein or supernatant from HIV-1 infected cells decreased kinase activity of p35 in these cells. These observations ascribe a role for Tat in altering p35 expression and its activity that affects phosphorylation of proteins involved in neuronal cell survival.     

Inhibition of Chikungunya virus infection in cultured human muscle cells by furin inhibitors: impairment of the maturation of the E2 surface glycoprotein

Chikungunya virus (CHIKV) is a mosquito-transmitted Alphavirus that causes in humans an acute infection characterized by polyarthralgia, fever, myalgia, and headache. Since 2005 this virus has been responsible for an epidemic outbreak of unprecedented magnitude. By analogy with other alphaviruses, it is thought that cellular proteases are able to process the viral precursor protein E3E2 to produce the receptor-binding E2 protein that associates as a heterodimer with E1. Destabilization of the heterodimer by exposure to low pH allows viral fusion and infection. We show that among a large panel of proprotein convertases, membranous furin but also PC5B can process E3E2 from African CHIKV strains at the HRQRR(64) / ST site, whereas a CHIKV strain of Asian origin is cleaved at RRQRR(64) / SI by membranous and soluble furin, PC5A, PC5B, and PACE4 but not by PC7 or SKI-1. Using fluorogenic model peptides and recombinant convertases, we observed that the Asian strain E3E2 model peptide is cleaved most efficiently by furin and PC5A. This cleavage was also observed in CHIKV-infected cells and could be blocked by furin inhibitor decanoyl-RVKR-chloromethyl ketone. This inhibitor was compared with chloroquine for its ability to inhibit CHIKV spreading in myoblast cell cultures, a cell-type previously described as a natural target of this virus. Our results demonstrate the role of furin-like proteases in the processing of CHIKV particles and point out new approaches to inhibit this infection.