Monoamine oxidase inhibitory activities of indolylalkaloid toxins from the venom of the colonial spider Parawixia bistriata: Functional characterization of PwTX-I

Colonial spiders evolved a differential prey-capture behaviour in concert with their venom chemistry, which may be a source of novel drugs. Some highly active tetrahydro-beta-carboline (TH beta C) toxins were recently isolated from the venom of the colonial spider Parawixia bistriata; the spiders use these toxins as part of their chemical arsenal to kill and/or paralyze preys. The major TH beta C compound isolated from this venom was identified as 6-hydroxytrypargine, also known as PwTX-I. Most natural compounds of animal origin occur in low abundance, and the natural abundance of PwTX-I is insufficient for complete functional characterization. Thus, PwTx-I was synthesized using a Pictet-Spengler condensation strategy, and the stereoisomers of the synthetic toxin were separated by chiral chromatography. The fraction of venom containing a mixture of three natural TH beta C toxins and enantiomers of PwTx-I were analyzed for inhibition of monoamine oxidase (MAO)-A and -B and for toxicity to insects. We reveal that the mixture of the natural TH beta C toxins, as well as the enantiomers of PwTx-I, were non-competitive inhibitors of MAO-A and MAO-B and caused potent paralysis of honeybees. The (-)-PwTX-I enantiomer is 2-fold more potent than the (+)-PwTX-I enantiomer in the assays performed. (C) 2009 Elsevier Ltd. All rights reserved.

Characterization of temperature dependent and substrate-binding cleft movements in Bacillus circulans family 11 xylanase: A molecular dynamics investigation

Background: Xylanases (EC 3.2.1.8) hydrolyze xylan, one of the most abundant plant polysaccharides found in nature, and have many potential applications in biotechnology. Methods: Molecular dynamics simulations were used to investigate the effects of temperature between 298 to 338 K and xylobiose binding on residues located in the substrate-binding cleft of the family 11 xylanase from Bacillus circulans (BcX). Results: In the absence of xylobiose the BcX exhibits temperature dependent movement of the thumb region which adopts an open conformation exposing the active site at the optimum catalytic temperature (328 K). In the presence of substrate, the thumb region restricts access to the active site at all temperatures, and this conformation is maintained by substrate/protein hydrogen bonds involving active site residues, including hydrogen bonds between Tyr69 and the 2` hydroxyl group of the substrate. Substrate access to the active site is regulated by temperature dependent motions that are restricted to the thumb region, and the BcX/substrate complex is stabilized by extensive intermolecular hydrogen bonding with residues in the active site. General significance: These results call for a revision of both the ""hinge-bending"" model for the activity of group 11 xylanases, and the role of Tyr69 in the catalytic mechanism. (C) 2009 Elsevier B.V. All rights reserved.

Physicochemical characterization of nanoparticles formed between DNA and phosphorylcholine substituted chitosans

The interactions between phosphorylcholine-substituted chitosans (PC-CH) and calf-thymus DNA (ct-DNA) were investigated focusing on the effects of the charge ratio, the pH, and phosphorylcholine content on the size and stability of the complexes using the ethidium bromide fluorescence assay, gel electrophoresis, dynamic light scattering. and fluorescence microscopy. The size and colloidal stability of deacetylated chitosan (CH/DNA) and PC-CH/DNA complexes were strongly dependent on phosphorylcholine content, charge ratios, and pH. The interaction strengths were evaluated from ethidium bromide fluorescence, and at N/P ratios higher than 5.0, no DNA release was observed in any synthesized PC-CH/DNA polyplexes by gel electrophoresis. The PC-CH/DNA polyplexes exhibited a higher resistance to aggregation compared to deacetylated chitosan (CH) at neutral pH. At low pH values highly charged chitosan and its phosphorylcholine derivatives had strong binding affinity with DNA, whereas at higher pH Values CH formed large aggregates and only C-CH derivatives were able to form small nanoparticles with hydrodynamic radii varying from 100 to 150 nm. Nanoparticles synthesized at low ionic strength with PC-CH derivatives containing moderate degrees of substitution (DS = 20% and 40%) remained stable for weeks. Photomicroscopies also confirmed that rhodamine-labeled PC(40)CH derivative nanoparticles presented higher colloidal stability than those synthesized using deacetylated chitosan. Accordingly, due to their improved physicochemical properties these phosphorylcholine-modified chitosans provide new perspectives for controlling the properties of polyplexes. (C) 2009 Elsevier Inc. All rights reserved.

Synthesis and characterization of trans-[Ru(NO)Cl(L)(4)](PF(6))(2) (L = isonicotinamide; 4-acetylpyridine) and related species

The trans-[RUCl(2)(L)(4)], trans-[Ru(NO)Cl (L)(4)](PF(6))(2) (L = isonicotinamide and 4-acetylpyridine) and trans-[Ru(NO)(OH)(py)(4)]Cl(2) (py = pyridine) complexes have been prepared and characterized by elemental analysis, UV-visible, infrared, and (1)H NMR spectroscopies, and cyclic voltammetry. The MLCT band energies of trans-[RUCl(2)(L)(4) increase in the order 4-acpy < isn < py. The reduction potentials of trans-[RuCl(2)(L)(4)] and trans-[Ru(NO)Cl(L)(4)](2+) increase in the order py < isn < 4-acpy. The stretching band frequency. v(NO), of the nitrosyl complexes ranges from 1913 to 1852 cm(-1) indicating a nitrosonium character for the NO ligand. Due to the large pi-acceptor ability of the equatorial ligands, the coordinated water is much more acidic in the water soluble trans-[Ru(NO)(H(2)O)(py)(4)](3+) than in trans-[Ru(NO)(H(2)O)(NH(3))(4)](3+) (C) 2009 Elsevier B.V. All rights reserved.

Characterization of rat behavior in the elevated plus-maze using a directed graph

The elevated plus-maze is a device widely used to assess rodent anxiety under the effect of several treatments, including pharmacological agents. The animal is placed at the center of the apparatus, which consists of two open arms and two arms enclosed by walls, and the number of entries and duration of stay in each arm are measured for a 5-min exposure period. The effect of an anxiolytic drug is to increase the percentage of time spent and number of entries into the open arms. In this work, we propose a new measure of anxiety levels in the rat submitted to the elevated plus-maze. We represented the spatial structure of the elevated plus-maze in terms of a directed graph and studied the statistics of the rat`s transitions between the nodes of the graph. By counting the number of times each transition is made and ordering them in descending frequency we represented the rat`s behavior in a rank-frequency plot. Our results suggest that the curves obtained under different pharmacological conditions can be well fitted by a power law with an exponent sensitive to both the drug type and the dose used. (C) 2009 Elsevier B.V. All rights reserved.

Characterization of the rat exploratory behavior in the elevated plus-maze with Markov chains

The elevated plus-maze is an animal model of anxiety used to study the effect of different drugs on the behavior of the animal It consists of a plus-shaped maze with two open and two closed arms elevated 50 cm from the floor The standard measures used to characterize exploratory behavior in the elevated plus-maze are the time spent and the number of entries in the open arms In this work we use Markov chains to characterize the exploratory behavior of the rat in the elevated plus-maze under three different conditions normal and under the effects of anxiogenic and anxiolytic drugs The spatial structure of the elevated plus-maze is divided into squares which are associated with states of a Markov chain By counting the frequencies of transitions between states during 5-min sessions in the elevated plus-maze we constructed stochastic matrices for the three conditions studied The stochastic matrices show specific patterns which correspond to the observed behaviors of the rat under the three different conditions For the control group the stochastic matrix shows a clear preference for places in the closed arms This preference is enhanced for the anxiogenic group For the anxiolytic group the stochastic matrix shows a pattern similar to a random walk Our results suggest that Markov chains can be used together with the standard measures to characterize the rat behavior in the elevated plus-maze (C) 2010 Elsevier B V All rights reserved

Molecular characterization of potentially zoonotic isolates of Giardia duodenalis in horses

Giardia isolates from eight horses from New York State (NY), USA and two horses from Western Australia (WA) were genetically characterized at the SSU-rDNA and triose-phosphate isomerase (TPI) genes. Phylogenetic analysis of the TPI gene provided strong support for the placement of both isolates of Giardia from horses in WA and a single isolate from a horse in NY within the assemblage AI genotype of G. duodenalis. Another two isolates from horses in NY placed within the assemblage All genotype of G. duodenalis. Phylogenetic analysis of the TPI gene also provided strong bootstrap support for the placement of four G. duodenalis isolates from horses in NY into a potentially host-specific sub-assemblage of assemblage BIV. The results of this study are consistent with previous studies showing that assemblages AI and AII of G. duodenalis provide the greatest potential zoonotic risk to humans. Horses may therefore constitute a potential source for human infection of Giardia either directly or via watersheds. (c) 2005 Elsevier B.V. All rights reserved.

Characterization of mechanical properties of silicon nitride thin films for MEMS devices by nanoindentation

An experimental investigation of mechanical properties of thin films using nanoindentation was reported. Silicon nitride thin films with different thicknesses were deposited using plasma enhanced chemical vapor deposition (PECVD) on Si substrate. Nanoindentation was used to measure their elastic modulus and hardness. The results indicated that for a film/substrate bilayer system, the measured mechanical properties are significantly affected by the substrate properties. Empirical formulas were proposed for deconvoluting the film properties from the measured bilayer properties.

Purification and Partial Characterization of an Exo-polygalacturonase from Paecilomyces variotii Liquid Cultures

An extracellular polygalacturonase (PG) produced from Paecilomyces variotii was purified to homogeneity through two chromatography steps using DEAE-Fractogel and Sephadex G-100. The molecular weight of P. variotii PG was 77,300 Da by gel filtration and SDS-PAGE. PG had isoelectric point of 4.37 and optimum pH 4.0. PG was very stable from pH 3.0 to 6.0. The extent of hydrolysis of different pectins by the purified enzyme was decreased with an increase in the degree of esterification. PG had no activity toward non-pectic polysaccharides. The apparent K (m) and V (max) values for hydrolyzing sodium polypectate were 1.84 mg/mL and 432 A mu mol/min/mg, respectively. PG was found to have temperature optimum at 65 A degrees C and was totally stable at 45 A degrees C for 90 min. Half-life at 55 A degrees C was 50.6 min. Almost all the examined metal cations showed partial inhibitory effects under enzymatic activity, except for Na(+1), K(+1), and Co(+2) (1 mM) and Cu(+2) (1 and 10 mM).

Characterization of optically driven fluid stress fields with optical tweezers

We present a controlled stress microviscometer with applications to complex fluids. It generates and measures microscopic fluid velocity fields, based on dual beam optical tweezers. This allows an investigation of bulk viscous properties and local inhomogeneities at the probe particle surface. The accuracy of the method is demonstrated in water. In a complex fluid model (hyaluronic acid), we observe a strong deviation of the flow field from classical behavior. Knowledge of the deviation together with an optical torque measurement is used to determine the bulk viscosity. Furthermore, we model the observed deviation and derive microscopic parameters.

Characterization of inflammatory responses to eccentric exercise in humans

Eccentric exercise commonly results in muscle damage. The primary sequence of events leading to exercise-induced muscle damage is believed to involve initial mechanical disruption of sarcomeres, followed by impaired excitation-contraction coupling and calcium signaling, and finally, activation of calcium-sensitive degradation pathways. Muscle damage is characterized by ultrastructural changes to muscle architecture, increased muscle proteins and enzymes in the bloodstream, loss of muscular strength and range of motion and muscle soreness. The inflammatory response to exercise-induced muscle damage is characterized by leukocyte infiltration and production of pro-inflammatory cytokines within damaged muscle tissue, systemic release of leukocytes and cytokines, in addition to alterations in leukocyte receptor expression and functional activity. Current evidence suggests that inflammatory responses to muscle damage are dependent on the type of eccentric exercise, previous eccentric loading (repeated bouts), age and gender. Circulating neutrophil counts and systemic cytokine responses are greater after eccentric exercise using a large muscle mass (e.g. downhill running, eccentric cycling) than after other types of eccentric exercise involving a smaller muscle mass. After an initial bout of eccentric exercise, circulating leukocyte counts and cell surface receptor expression are attenuated. Leukocyte and cytokine responses to eccentric exercise are impaired in elderly individuals, while cellular infiltration into skeletal muscle is greater in human females than males after eccentric exercise. Whether alterations in intracellular calcium homeostasis influence inflammatory responses to muscle damage is uncertain. Furthermore, the effects of antioxidant supplements are variable, and the limited data available indicates that anti-inflammatory drugs largely have no influence on inflammatory responses to eccentric exercise. In this review, we compare local versus systemic inflammatory responses, and discuss some of the possible mechanisms regulating the inflammatory responses to exercise-induced muscle damage in humans.

Characterization of blood-filled cyst by contrast echocardiography and computed tomography

Contrast echocardiography has been demonstrated useful for left ventricular opacification and improvement of endocardial border delineation. Another important clinical application of this technique refers to the better characterization of cardiac tumors and masses. We here described an asymptomatic patient with cystic mass attached to submitral valve apparatus in which contrast echocardiography was performed after intravenous injection of lipid-encapsulated microbubbles. It resulted in enhancement of the cystic borders and allowed for better definition of its diagnosis. Multislice computed tomography confirmed the echocardiographic findings. This case illustrates the potential of contrast echocardiography to improve the anatomic evaluation of cardiac masses.

Improved comparison plot method for pore structure characterization of MCM-41

MCM-41 samples of various pore dimensions are synthesized. Plotting of nitrogen adsorption data at 77 K versus the statistical film thickness (comparison plot) reveals three distinct stages, with a characteristic of two points of inflection. The steep intermediate stage caused by capillary condensation occurred in the highly uniform mesopores. From the slopes of the sections before and after the condensation, the surface area of the mesopores is calculated. The linear portion of the last section is extrapolated to the adsorption axis of the comparison plot, and this intercept is used to obtain the volume of the mesopores. From the surface area and pore volume, average mesopore diameter is calculated, and the value thus obtained is in good agreement with the pore dimension obtained from powder X-ray diffraction measurements. The principle of the calculation as well as problems associated are discussed in detail.

Identification and characterization of a G protein-coupled receptor homolog encoded by murine cytomegalovirus

This report describes the identification of a murine cytomegalovirus (MCMV) G protein-coupled receptor (GCR) homolog. This open reading frame (M33) is most closely related to, and collinear with, human cytomegalovirus UL33, and homologs are also present in human herpesvirus 6 and 7 (U12 for both viruses). Conserved counterparts in the sequenced alpha- or gammaherpesviruses have not been identified to date, suggesting that these genes encode proteins which are important for the biological characteristics of betaherpesviruses. We have detected transcripts for both UL33 and M33 as early as 3 or 4 h postinfection, and these reappear at late times. In addition, we have identified N-terminal splicing for both the UL33 and M33 RNA transcripts. For both open reading frames, splicing results in the introduction of amino acids which are highly conserved among known GCRs. To characterise the function of the M33 in the natural host, two independent MCMV recombinant viruses were prepared, each of which possesses an M33 open reading frame which has been disrupted with the beta-galactosidase gene. While the recombinant M33 null viruses showed no phenotypic differences in replication from wild-type MCMV in primary mouse embryo fibroblasts in vitro, they showed severely restricted growth in the salivary glands of infected mice. These data suggest that M33 plays an important role in vivo, in particular in the dissemination to or replication in the salivary gland, and provide the first evidence for the function of a viral GCR homolog in vivo.