Determination of viability of Aeromonas hydrophila in increasing concentrations of sodium chloride at different temperatures by flow cytometry and plate count technique

Aeromonads in waters and foods can represent a risk to human health. Factors such as sodium chloride concentration and temperature can affect growth and viability of several food and water-borne pathogens. The behaviour of an Aeromonas hydrophila strain in the presence of 1.7%, 3.4% and 6% NaCl concentrations at 24 degrees C and 4 degrees C was studied over a 188 day period. Viability and membrane potential were assessed by flow cytometry; growth was evaluated by plate count technique. Flow cytometry evidenced that A. hydrophila retained viability over the period although varying according to temperature and salt concentrations. Colony Forming Units were generally lower in number than viable cells especially in the presence of 6% NaCl, indicating the occurrence of stressed cells which maintain metabolic activity yet are not able to grow on agar plates. In conclusion, A. hydrophila showed a long-term halotolerance even at elevated (6%) NaCl concentrations and a lesser sensitivity to salt at low temperature; therefore, low temperature and salt, which are two important factors limiting bacterial growth, do not assure safety in the case of high initial contamination. Finally, cytometry appears a valid tool for the rapid detection of the viability of pathogenic bacteria in food and environmental matrices to control and prevent health risks.     

Internalization and Accumulation in Dendritic Cells of a Small pH‐Activatable Glycomimetic Fluorescent Probe as Revealed by Spectral Detection

DC‐SIGN, an antigen‐uptake receptor in dendritic cells (DCs), has a clear role in the immune response but, conversely, can also facilitate infection by providing entry of pathogens into DCs. The key action in both processes is internalization into acidic endosomes and lysosomes. Molecular probes that bind to DC‐SIGN could thus provide a useful tool to study internalization and constitute potential antagonists against pathogens. So far, only large molecules have been used to directly observe DC‐SIGN‐mediated internalization into DCs by fluorescence visualization. We designed and synthesized an appropriate small glycomimetic probe. Two particular properties of the probe were exploited: activation in a low‐pH environment and an aggregation‐induced spectral shift. Our results indicate that small glycomimetic molecules could compete with antigen/pathogen for binding not only outside but also inside the DC, thus preventing the harmful action of pathogens that are able to intrude into DCs, for example, HIV‐1.     

Structure‐Based Mechanism of Oleate Hydratase from Elizabethkingia meningoseptica

Hydratases provide access to secondary and tertiary alcohols by regio‐ and/or stereospecifically adding water to carbon‐carbon double bonds. Thereby, hydroxy groups are introduced without the need for costly cofactor recycling, and that makes this approach highly interesting on an industrial scale. Here we present the first crystal structure of a recombinant oleate hydratase originating from Elizabethkingia meningoseptica in the presence of flavin adenine dinucleotide (FAD). A structure‐based mutagenesis study targeting active site residues identified E122 and Y241 as crucial for the activation of a water molecule and for protonation of the double bond, respectively. Moreover, we also observed that two‐electron reduction of FAD results in a sevenfold increase in the substrate hydration rate. We propose the first reaction mechanism for this enzyme class that explains the requirement for the flavin cofactor and the involvement of conserved amino acid residues in this regio‐ and stereoselective hydration.     

Graft copolymerization of acrylonitrile and methacrylonitrile onto gelatin by mutual irradiation method

In order to improve upon certain properties of gelatin graft copolymerization of acrylonitrile (AN) and methacrylonitrile (MAN) onto gelatin has been studied in aqueous medium using γ rays as a source of initiation. Optimum conditions for affording maximum percentage of grafting have been evaluated as a function of various reaction parameters. The grafted polyacrylonitrile (PAN) was isolated from the graft copolymer by acid hydrolysis, and the average molecular weight (M_v) of the isolated polymer has been determined viscometrically. The graft copolymers were characterized by IR spectroscopic methods and thermogravimetric analysis (TGA). Acrylonitrile was found to be more reactive than methacrylonitrile toward graft copolymerization. © 1994 John Wiley & Sons, Inc.     

Biosorption of nickel ions from aqueous solutions by natural and modified peanut husks: equilibrium and kinetics

The toxicity and non‐biodegradation of heavy metals, as well as their tendency to accumulate in the soils, water resources and the living organisms, makes them the significant environmental pollutants. Therefore, the reduction and elimination of heavy metal ions from aqueous systems is very important from the ecological, nutritional and environmental reasons. The aim of this study is to investigate whether the natural peanut husks, an agricultural waste, and their chemically modified form are capable to remove Ni(II) ions from aqueous solutions using batch method and to compare their efficiency. The effects of the mass of the natural peanut husks and the initial pH of the solution were studied to find the optimal conditions for maximal removal of Ni(II) ions. MATLAB/Curve Fitting Toolbox was implemented to determine the adequate adsorption isotherm as well as to optimise the equilibrium state of the investigated systems.     

Parenting moderates a genetic vulnerability factor in longitudinal increases in youths' substance use.

The authors used a longitudinal, prospective design to investigate a moderation effect in the association between a genetic vulnerability factor, a variable nucleotide repeat polymorphism in the promoter region of 5HTT (5-HTTLPR), and increases in youths' substance use. The primary study hypothesis predicted that involved-supportive parenting would attenuate the link between the 5-HTTLPR polymorphism and longitudinal increases in substance use. African American youths residing in rural Georgia (N = 253, mean age = 11.5 years) provided 4 waves of data on their own substance use; the mothers of the youths provided data on their own parenting practices. Genetic data were obtained from youths via saliva samples. Latent growth curve modeling indicated that 5-HTTLPR status (presence of 1 or 2 copies of the s allele) was linked with increases in substance use over time; however, this association was greatly reduced when youths received high levels of involved-supportive parenting. This study demonstrates that parenting processes have the potential to ameliorate genetic risk. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Winning and positive affect can lead to reckless gambling.

Experiments 1 and 2 examined whether winning versus losing led to reckless betting for real prize money. Experiment 2 also assessed whether positive or negative emotions were linked to such reckless betting. College students were randomly assigned to experience primarily either wins or losses during the rigged first round of a computerized card tournament that had 2 independent rounds. For the second round, participants’ chip totals were reset and cards were dealt randomly. In Experiment 1 (N = 107), participants in the Initial-Winning, as compared with the Initial-Losing, condition bet more recklessly (i.e., bet too many chips when a loss was likely). Experiment 2 (N = 72) again showed that Initial-Winning participants bet significantly more recklessly than did Initial-Losing participants. It also revealed that positive affect was significantly positively correlated with such reckless betting. These findings have implications for understanding how college students, those at an age when they are especially vulnerable to problem gambling, can come to lose more money than they can afford. Initially winning and positive affect when gambling could be risk factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characteristics of traditionally processed shea kernels and butter

The traditional production of shea butter requires a heat treatment of the nuts. This study compared the end products derived by two commonly used heat treatments, namely smoking and boiling followed by sun‐drying. Neither treatment influenced the moisture content of the kernels (8–10%), but the boiling treatment resulted in more free fatty acids (FFA) (6%) and a higher fat content (41%) of kernels. A sensory panel preferred shea butter from boiled kernels because of its soft texture and intense smell. This butter also had the highest values for moisture content (2%), unsaponifiable matter (7%), tocopherol compounds (125 mg g^?1), peroxide value (8 meq O₂ kg^?1), iodine value (53 mg I₂ 100 g^?1) and FFA (2%). Minor variations were noticed in the fatty acid profile. Aside from the use of butter from both boiled and smoked kernels in cosmetics, the butter from smoked kernels will be more suitable for food purposes.