Genotyping, physiological features and proteolytic activities of a potentially pathogenic Acanthamoeba sp isolated from tap water in Brazil

Acanthamoeba spp., known to cause keratitis and granulomatous encephalitis in humans, are frequently isolated from a variety of water sources. Here we report for the first time the characterization of an Acanthamoeba sp. (ACC01) isolated from tap water in Brazil. This organism is currently being maintained in an axenic growth medium. Phylogenetic analysis based on SSU rRNA gene sequences positioned the new isolate in genotype T4, closest to the keratitis-causing isolate, A. polyphaga ATCC 30461 (similar to 99% similarity). Acanthamoeba ACC01 and A. polyphaga 30461 both grew at 37 degrees C and were osmotically resistant, multiplying in hyperosmolar medium. Both isolates secreted comparable amounts of proteolytic enzymes, including serine peptidases that were optimally active at a near neutral/alkaline pH and resolved identically in gelatin gels. Incubation of gels at pH 4.0 with 2 mM DTT also indicated the secretion of similar cysteine peptidases. Altogether, the results point to the pathogenic potential of Acanthamoeba ACC01. (C) 2009 Elsevier Inc. All rights reserved.

Susceptible-infected-recovered and susceptible-exposed-infected models

Two stochastic epidemic lattice models, the susceptible-infected-recovered and the susceptible-exposed-infected models, are studied on a Cayley tree of coordination number k. The spreading of the disease in the former is found to occur when the infection probability b is larger than b(c) = k/2(k - 1). In the latter, which is equivalent to a dynamic site percolation model, the spreading occurs when the infection probability p is greater than p(c) = 1/(k - 1). We set up and solve the time evolution equations for both models and determine the final and time-dependent properties, including the epidemic curve. We show that the two models are closely related by revealing that their relevant properties are exactly mapped into each other when p = b/[k - (k - 1) b]. These include the cluster size distribution and the density of individuals of each type, quantities that have been determined in closed forms.

A new scale-invariant ratio and finite-size scaling for the stochastic susceptible-infected-recovered model

The critical behavior of the stochastic susceptible-infected-recovered model on a square lattice is obtained by numerical simulations and finite-size scaling. The order parameter as well as the distribution in the number of recovered individuals is determined as a function of the infection rate for several values of the system size. The analysis around criticality is obtained by exploring the close relationship between the present model and standard percolation theory. The quantity UP, equal to the ratio U between the second moment and the squared first moment of the size distribution multiplied by the order parameter P, is shown to have, for a square system, a universal value 1.0167(1) that is the same for site and bond percolation, confirming further that the SIR model is also in the percolation class.

Epidemics in networks of spatially correlated three-dimensional root-branching structures

Using digitized images of the three-dimensional, branching structures for root systems of bean seedlings, together with analytical and numerical methods that map a common susceptible-infected- recovered (`SIR`) epidemiological model onto the bond percolation problem, we show how the spatially correlated branching structures of plant roots affect transmission efficiencies, and hence the invasion criterion, for a soil-borne pathogen as it spreads through ensembles of morphologically complex hosts. We conclude that the inherent heterogeneities in transmissibilities arising from correlations in the degrees of overlap between neighbouring plants render a population of root systems less susceptible to epidemic invasion than a corresponding homogeneous system. Several components of morphological complexity are analysed that contribute to disorder and heterogeneities in the transmissibility of infection. Anisotropy in root shape is shown to increase resilience to epidemic invasion, while increasing the degree of branching enhances the spread of epidemics in the population of roots. Some extension of the methods for other epidemiological systems are discussed.

Random walks systems with killing on Z

We study random walks systems on Z whose general description follows. At time zero, there is a number N >= 1 of particles at each vertex of N, all being inactive, except for those placed at the vertex one. Each active particle performs a simple random walk on Z and, up to the time it dies, it activates all inactive particles that it meets along its way. An active particle dies at the instant it reaches a certain fixed total of jumps (L >= 1) without activating any particle, so that its lifetime depends strongly on the past of the process. We investigate how the probability of survival of the process depends on L and on the jumping probabilities of the active particles.

RUMOR PROCESSES ON N

We study four discrete-time stochastic systems on N, modeling processes of rumor spreading. The involved individuals can either have an active or a passive role, speaking up or asking for the rumor. The appetite for spreading or hearing the rumor is represented by a set of random variables whose distributions may depend on the individuals. Our goal is to understand-based on the distribution of the random variables-whether the probability of having an infinite set of individuals knowing the rumor is positive or not.

NONHOMOGENEOUS RANDOM WALKS SYSTEMS ON Z

We consider a random walks system on Z in which each active particle performs a nearest-neighbor random walk and activates all inactive particles it encounters. The movement of an active particle stops when it reaches a certain number of jumps without activating any particle. We prove that if the process relies on efficient particles (i.e. those particles with a small probability of jumping to the left) being placed strategically on Z, then it might survive, having active particles at any time with positive probability. On the other hand, we may construct a process that dies out eventually almost surely, even if it relies on efficient particles. That is, we discuss what happens if particles are initially placed very far away from each other or if their probability of jumping to the right tends to I but not fast enough.

Att iscensätta apokalypsen : zombiemetaforer i den samtida katastrofberedskapen

Enacting the apocalypse: zombie metaphors in contemporary disaster preparedness Since the turn of the millennium, enactment of possible emergencies and catastrophes has become a most common way of producing knowledge about events yet to occur. Preparedness exercises are frequently performed by public authorities at local and regional levels. Collaborative approaches among relevant actors are enhanced and evaluated through simulated accidents and acts of terror as well as school shootings and epidemic outbreaks. Due to the incalculability of many modern threats, enactment is employed as a method for rendering potential future events available as empirical phenomena. However, sometimes these potential futures are represented in ways that correspond only to imagined and fictional worlds. The aim of this article is to explore the enactment of unreal possibilities in contemporary preparedness exercises. The empirical material employed for this purpose consists of crisis plans and exercise guides used in public and official institutions in the United States as well as qualitative interviews with municipal safety coordinators in Sweden.

Motiverande samtal mellan sjuksköterskan och personer med diabetes typ 2 – en litteraturöversikt

Bakgrund: Antalet personer med diabetes i världen ökar. Det har blivit en global epidemi. Risken för dödsfall bland människor med diabetes, är ungefär dubbelt så stor, som för människor i samma ålder utan diabetes. Diabetes typ 2 (DT2) är den vanligaste typen av diabetes. Inom hälso- och sjukvården används alltmer motiverande samtal (MI) som behandlingsmetod för livsstilsrelaterade problem som till exempel: kost, motion alkohol och tobak. Syfte: Syftet med studien var att beskriva hur sjuksköterskans användning av MI påverkar livsstilsförändringar hos personer med DT2 och deras upplevelse av behandlingen. Metod: En litteraturöversikt. Resultat: MI som behandlingsmetod gav flera positiva hälsoeffekter. Det framgick bland annat genom en sänkning av HbA1c. Även kunskapsnivån gällande livsstilsförändringar ökade efter MI-behandling. Vid användning av MI stärktes personens inneboende motivation till förändring. Slutsats: MI är en relativt ny metod som ännu inte fått stor genomslag inom diabetesvården. MI ger positiva hälsoeffekter som till exempel sänkt HbA1c. Deltagarna blev mer motiverade och medvetna om sitt eget ansvar för att göra livsstilsförändringar. Mer forskning om MI för personer med DT2 behövs.