Enzyme-immunoassay for the determination of metallothionein in human urine: application to environmental monitoring.

The objectives of this study were to develop an enzyme immunoassay for metallothioneins in human urine using a polyclonal antiserum and to demonstrate a possible relationship between the level of this biomarker and heavy metal exposure. The antiserum was raised in sheep against horse metallothionein conjugated to carboxylated bovine serum albumin. The antibody was used to construct a two-step competitive ELISA procedure. Human urine was treated with activated charcoal powder to remove traces of metallothioneins and known amounts of pure metallothioneins were added to provide standards for a standard curve. Metallothionein levels were measured in two groups of children living in areas of mild and high environmental pollution due mainly to heavy metals. A comparison was made between the biomarker levels and the levels of cadmium and lead in urine samples in the two groups. A group of children from a non-polluted area acted as controls. The results show that the detected levels of metallothioneins appear to correspond to levels of the two heavy metals studied and that there was an apparent relationship to the environmental exposure. Thus according to results of this study the increase in the metallothionein excretion seems to provide an indication of previous of exposure to metals. The ELISA procedure is sensitive and robust and can be used to screen large numbers of samples and is more rapid than the physical procedures currently used for analysis of these proteins. The assay can therefore be used as an additional tool for screening at-risk populations where either environmental or occupational exposure to divalent heavy metals is suspected.     

Societal Risk Perception in Arab Countries: The Case of Kuwait

The study was aimed at examining data on risk perception from an Arab country—Kuwait—in order to support the existence of an Arab group as regards the way hazards are perceived. The data were gathered in 2003 and 2004 on two Kuwaiti samples of young adults and adolescents. The questionnaire used was the one used in studies conducted in Egypt and France. It comprised 141 items. The overall mean value observed in the Kuwaiti sample was close to the one found in the Egyptian sample. The linear association between Kuwaiti and French ratings was moderate (0.70) and of the same magnitude as the one found between Egyptian and French ratings. The association between Kuwaiti and Egyptian ratings was greater (0.90). In 80% of the hazards, the specific differences observed between the Kuwaiti and French ratings were the same as the ones observed between Egyptian and French ratings. The whole set of findings supports the hypothesis that Kuwaitis and Egyptians, despite huge differences in the socioeconomic environments in which they live, perceive societal risks in a common way, a way that is different from the way Western Europeans perceive them.     

Photo oxidation of rice starch II. Using a water soluble photo initiator

A new photo oxidation system was established when rice starch was oxidized using UV irradiation and 4-(trimethyl ammoniummethyl) benzophenone chloride (BP2) as a photo initiator. BP2 is a water soluble photo initiator. The slurry prepared for photo oxidation contained rice starch, water and BP2 only. No oxidizing agents were added. Parameters affecting the photo oxidation process, i.e. temperature, concentration of BP2, material:liquor ratio and irradiation time were determined. The produced oxidized starch was evaluated by measuring the carboxyl content, carbonyl content and apparent viscosity. The produced photo oxidized rice starch showed sound increase in the carboxyl and carbonyl contents and sharp decrease in the apparent viscosity. The produced photo oxidized starch was tested for its suitability as a sizing agent for cotton yarns. Native starch and oxidized starch, used as a sizing agent by Misr Company of Spinning and Weaving in El-Mahalla El-Kubra (Egypt), were used for comparison. Sized cotton yarns were evaluated by measuring the tensile strength, elongation at break and percent of size removal. Cotton yarns sized using the prepared photo oxidized rice starch showed higher tensile strength, elongation at break and percent of size removal compared with native starch and oxidized starch used by Misr Company of Spinning and Weaving.     

Chemical characteristics and antioxidant activity of exopolysaccharide fractions from Microbacterium terregens

The Gram-positive bacterial strain isolated from soil was identified as the non-pathogenic Microbacterium terregens. The exopolysaccharide (CPS) produced from M. terregens was obtained by isopropanol precipitation (13.72 g L^?1 growth medium), The resulted exopolysaccharide was purified by chromatography on DEAE-cellulose and Sephacryl S-200 columns, when two polysaccharide fractions termed CPSI and CPSII were obtained. Structure features of CPSI and CPSII were investigated by a combination of chemical and chromatographic analyses, such as acid hydrolysis, methylation analysis, periodate oxidation–Smith degradation, HPLC, GC–MS, and IR. The results indicated that CPSI and CPSII were composed of glucose: mannose in a ratio of 2.7:1 and 3.2:1 with molecular weights 80 and 150 kDa, respectively. It has a backbone of (1 → 4)-linked β-glucose residues, which occasionally branches at O-6. The branches were composed of (1 → 4)-linked β-mannose residues. The antioxidant activity of the CPS, CPSI and CPSII was evaluated in-vitro by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay (RSA). CPSI fraction showed the highest antioxidant activity among the three fractions, with an IC₅₀ value of 230 μg mL^?1. The effect of molecular weight of the polysaccharide on the improvement of the antioxidant potential seems to be significant.     

New development for combined bioscouring and bleaching of cotton-based fabrics

A thorough investigation into conditions appropriate for effecting combined eco-friendly bioscouring and/or bleaching of cotton-based fabrics was undertaken. Fabrics used include cotton, grey mercerized cotton, cotton/polyester blend 50/50 and cotton/polyester blend 35/65. The four cotton-based fabric were subjected to bioscouring by single use of alkaline pectinase enzymes or by using binary mixtures of alkaline pectinase and cellulase enzymes under a variety of conditions. Results of bioscouring show that, the bioscoured substrates exhibit fabrics performances which are comparable with these of the conventional alkali scouring. It has been also found that, incorporation of ethylenediaminetetraacetic acid (EDTA) in the bioscouring with mixture from alkaline pectinase and cellulase improves the performance of the bioscoured fabrics. Addition of β-cyclodextrin to the bioscouring solution using alkaline pectinase in admixtures with cellulase acts in favor of technical properties and performance of the bioscoured fabrics. Concurrent bioscouring and bleaching by in situ formed peracetic acid using tetraacetylethylenediamine (TAED) and H₂O₂ was also investigated. The results reveal unequivocally that the environmentally sound technology brought about by current development is by far the best. The new development involves a single-stage process for full purification/preparation of cotton textiles. The new development at its optimal comprises treatment of the fabric with an aqueous formulation consisting of alkaline pectinase enzyme (2 g/L), TAED (15 g/L), H₂O₂ (5 g/L), nonionic wetting agent (0.5 g/L) and sodium silicate (2 g/L). The treatment is carried out at 60 °C for 60 min. Beside the advantages of the new development with respect to major technical fabric properties, it is eco-friendly and reproducible. This advocates the new development for mill trials.     

Characterization of bacterial proteases with a panel of fluorescent peptide substrates

Bacteria produce a range of proteolytic enzymes. In an attempt to detect and identify bacteria on the basis of their protease activity, a panel of protease substrates was investigated. Peptides conjugated to the fluorophore 7-amino-4-methylcoumarin (AMC) are well-established substrates for measuring protease activity. Although peptide-AMC substrates are generally not specific for a single protease, a unique pattern can be achieved for both highly specific enzymes and those with a broader substrate range by comparing different peptide substrates. The panel of 7 peptide-AMC substrates chosen exhibited a unique pattern for nine microbial proteases. The selected peptides were used to determine protease activity in cultured strains of Pseudomonas aeruginosa and Staphylococcus aureus. A signal pattern obtained with peptides with arginine, lysine, and tyrosine in the P1 position characterized the bacterial protease activities in these samples. The kinetic parameters for the three best substrates for the P. aeruginosa sample were calculated. Further information about substrate specificity was gained by the selective use of protease inhibitors. The results presented show that peptide-AMC substrates provide a simple and sensitive tool to characterize protease activity in microbiological samples and that they have the potential to identify and distinguish different bacterial species.     

An integrated microfluidic platform for magnetic microbeads separation and confinement

An innovative microfluidic platform for magnetic beads manipulation is introduced, consisting of novel microfabricated 3D magnetic devices positioned in a microfluidic chamber. Each magnetic device comprises of an embedded actuation micro-coil in various design versions, a ferromagnetic pillar, a magnetic backside plate and a sensing micro-coil. The various designs of the micro-coils enable efficient magnetic beads trapping and concentration in different patterns. The finite element analysis (FEA) results show a significant increase of the developed force on suspended magnetic beads when the magnetic pillar and backside plate were integrated into the device structure. These simulation results were confirmed experimentally by measuring the magnetic beads trapping ratios for the different designs and structures of the devices under continuous flow conditions. The trapping ratios and profiles were studied using beads counting, measuring the change of inductance with the sensing micro-coil and by image processing. The devices have efficiently demonstrated a controlled and localized magnetic beads trapping and concentration at small spatial locations for the first time. The new results shown in this study demonstrate the feasibility of efficiently using these original devices as key elements in complex bio-analysis systems.