Effect of Metalaxyl on the incidence and severity of Pearl millet downy mildew disease in Northern Nigeria

Pearl millet downy mildew (DM) incidence, severity and yield losses of two pearl millet varieties (local and improved) due to the disease were determined in the field. Significant differences in the disease incidence and severity were recorded in the plots sown with metalaxyl-treated seeds and those sown with non-treated seeds, indicating the efficacy of the fungicide on the fungus. Yield losses due to non-treatment of seeds with metalaxyl was 40.88 and 45.39% in a local variety and 43.00 and 18.60% in an improved variety in the 2000 and 2001 cropping seasons respectively. Significant differences between plots sown with metalaxyl-treated and those sown with non-treated seeds were obtained for other yield components such as 1000-grains weight, panicle length and weight.     

Reducing infectivity of HIV upon exposure to surfaces coated with N,N‐dodecyl,methyl‐polyethylenimine

The infectivity of high‐titer, cell‐free HIV in culture media and human milk is rapidly reduced upon exposure to polyethylene slides painted with the linear hydrophobic polycation N,N‐dodecyl,methyl‐polyethylenimine (DMPEI). Accompanying viral p24 protein and free viral RNA analysis of solutions exposed to DMPEI‐coated surfaces suggests that virion attachment to the polycationic surface and its subsequent inactivation are the likely mechanism of this phenomenon. Biotechnol. Bioeng. 2013; 110: 2058–2062. © 2013 Wiley Periodicals, Inc.     

Preparation, application and testing of permanent antibacterial and antiviral coatings

Protocols for the synthesis of the microbicidal polycation N,N-dodecyl,methyl-polyethylenimine and coating (painting) of glass slides with this polycation's butanol solution are described. Subsequently detailed are the procedures for validating that the resultant coated slides are essentially 100% lethal to the human bacterial pathogens, Staphylococcus aureus and Escherichia coli, as well as to two common strains of influenza virus. The time required to prepare and apply the cationic polymer and to test its microbicidal efficiency is conservatively estimated to be <4 weeks.     

Structure of lysozyme dissolved in neat organic solvents as assessed by NMR and CD spectroscopies

The structure of the model protein hen egg-white lysozyme dissolved in water and in five neat organic solvents (ethylene glycol, methanol, dimethylsulfoxide (DMSO), formamide, and dimethylformamide (DMF)) has been examined by means of 1H NMR and circular dichroism (CD) spectroscopies. The NMR spectra of lysozyme reveal the lack of a defined tertiary structure in all five organic solvents, although the examination of line widths suggests the possibility of some ordered structure in ethylene glycol and in methanol. The near-UV CD spectra of the protein suggest no tertiary structure in lysozyme dissolved in DMSO, formamide, and DMF, while a distinctive (albeit less pronounced than in water) tertiary structure is seen in ethylene glycol and a drastically changed one in methanol. A highly developed secondary structure was observed by far-UV CD in ethylene glycol and methanol; interestingly, the alpha-helix content of the protein in both was greater than in water, while the beta-structure content was lower. (Solvent absorbance in the far-UV region prevents conclusions about the secondary structure in DMSO, formamide and DMF.) Copyright 1999 John Wiley & Sons, Inc.     

Effect of temperature on the saccharide composition obtained after alpha-amylolysis of starch

The hydrolysis of starch to low-molecular-weight products (normally characterised by their dextrose equivalent (DE), which is directly related to the number-average molecular mass) was studied at different temperatures. Amylopectin potato starch, lacking amylose, was selected because of its low tendency towards retrogradation at lower temperatures. Bacillus licheniformis alpha-amylase was added to 10% [w/w] gelatinised starch solutions. The hydrolysis experiments were done at 50, 70, and 90 degrees C. Samples were taken at defined DE values and these were analysed with respect to their saccharide composition. At the same DE the oligosaccharide composition depended on the hydrolysis temperature. This implies that at the same net number of bonds hydrolysed by the enzyme, the saccharide composition was different. The hydrolysis temperature also influenced the initial overall molecular-weight distribution. Higher temperatures led to a more homogenous molecular weight distribution. Similar effects were observed for alpha-amylases from other microbial sources such as Bacillus amyloliquefaciens and Bacillus stearothermophilus. Varying the pH (5.1, 6.2, and 7.6) at 70 degrees C did not significantly influence the saccharide composition obtained during B. licheniformis alpha-amylase hydrolysis. The underlying mechanisms for B. licheniformis alpha-amylase were studied using pure linear oligosaccharides, ranging from maltotriose to maltoheptaose as substrates. Activation energies for the hydrolysis of individual oligosaccharides were calculated from Arrhenius plots at 60, 70, 80, and 90 degrees C. Oligosaccharides with a degree of polymerisation exceeding that of the substrate could be detected. The contribution of these oligosaccharides increased as the degree of polymerisation of the substrate decreased and the temperature of hydrolysis increased. The product specificity decreased with increasing temperature of hydrolysis, which led to a more equal distribution between the possible products formed. Calculations with the subsite map as determined for the closely related alpha-amylase from B. amyloliquefaciens reconfirmed this finding of a decreased substrate specificity with increased temperature of hydrolysis. Copyright 1999 John Wiley & Sons, Inc.     

Microvascular remodeling and accelerated hyperemia blood flow restoration in arterially occluded skeletal muscle exposed to ultrasonic microbubble destruction

We showed previously that microbubble destruction with pulsed 1-MHz ultrasound creates a bioeffect that stimulates arteriogenesis and a chronic increase in hyperemia blood flow in normal rat muscle. Here we tested whether ultrasonic microbubble destruction can be used to create a microvascular remodeling response that restores hyperemia blood flow to rat skeletal muscle affected by arterial occlusion. Pulsed ultrasound (1 MHz) was applied to gracilis muscles in which the lateral feed artery was occluded but the medial feed artery was left intact. Control muscles were similarly occluded but did not receive ultrasound, microbubbles, or both. Hyperemia blood flow and number of smooth muscle (SM) alpha-actin-positive vessels, >30-mum arterioles, and capillaries per fiber were determined 7, 14, and 28 days after treatment. In ultrasound-microbubble-treated muscles, lateral region hyperemia blood flow was increased at all time points and restored to normal at day 28. The number of SM alpha-actin vessels per fiber was increased over control in this region at days 7 and 14 but decreased by day 28, when larger-diameter arterioles became more prevalent in the medial region. The number of capillaries per fiber was increased over control only at day 7 in the lateral region and only at days 7 and 14 in the medial region, indicating that the angiogenesis response was transient and likely did not contribute significantly to flow restoration at day 28. We conclude that ultrasonic microbubble destruction can be tailored to stimulate an arteriogenesis response that restores hyperemia blood flow to skeletal muscle in a rat model of arterial occlusion.     

Mechanism of bactericidal and fungicidal activities of textiles covalently modified with alkylated polyethylenimine

Our previous studies have led to a novel "nonrelease" approach to making materials bactericidal by covalently attaching certain moderately hydrophobic polycations to their surfaces. In the present work, this strategy is extended beyond the heretofore-used nonporous materials to include common woven textiles (cotton, wool, nylon, and polyester). Pieces of such cloths derivatized with N-hexylated+methylated high-molecular-weight polyethylenimine (PEI) are strongly bactericidal against several airborne Gram-positive and Gram-negative bacteria. In contrast, the immobilized and N-alkylated PEIs of low molecular weight have only a weak, if any, bactericidal activity. These findings support a mechanism of the antibacterial action whereby high-molecular-weight and hydrophobic polycationic chains penetrate bacterial cell membranes/walls and fatally damage them. The bactericidal textiles prepared herein are lethal not only to pathogenic bacteria but to fungi as well.