Modelling of ciprofloxacin killing enhanced by hyperbaric oxygen treatment in Pseudomonas aeruginosa PAO1 biofilms

<div><p>Outline</p><p>In chronic lung infections by <i>Pseudomonas aeruginosa</i> (PA) the bacteria thrive in biofilm structures protected from the immune system of the host and from antibiotic treatment. Increasing evidence suggests that the susceptibility of the bacteria to antibiotic treatment can be significantly enhanced by hyperbaric oxygen treatment. The aim of this study is to simulate the effect of ciprofloxacin treatment in a PAO1 biofilm model with aggregates in agarose when combined with hyperbaric oxygen treatment. This is achieved in a reaction-diffusion model that describes the combined effect of ciprofloxacin diffusion, oxygen diffusion and depletion, bacterial growth and killing, and adaptation of the bacteria to ciprofloxacin. In the model, the oxygen diffusion and depletion use a set of parameters derived from experimental results presented in this work. The part of the model describing ciprofloxacin killing uses parameter values from the literature in combination with our estimates (Jacobs, et al., 2016; Grillon, et al., 2016). Micro-respirometry experiments were conducted to determine the oxygen consumption in the <i>P. aeruginosa</i> strain PAO1. The parameters were validated against existing data from an HBOT experiment by Kolpen <i>et al.</i> (2017). The complete oxygen model comprises a reaction-diffusion equation describing the oxygen consumption by using a Michaelis-Menten reaction term. The oxygen model performed well in predicting oxygen concentrations in both time and depth into the biofilm. At 2.8 bar pure oxygen pressure, HBOT increases the penetration depth of oxygen into the biofilm almost by a of factor 4 in agreement with the scaling that follows from the stationary balance between the consumption term and diffusion term.</p><p>Conclusion</p><p>In the full reaction-diffusion model we see that hyperbaric oxygen treatment significantly increases the killing by ciprofloxacin in a PAO1 biofilm in alignment with the experimental results from Kolpen <i>et al.</i> (Kolpen, et al., 2017; Kolpen, et al. 2016). The enhanced killing, in turn, lowers the oxygen consumption in the outer layers of the biofilm, and leads to even deeper penetration of oxygen into the biofilm.</p></div

Recent Cases: Treaties. Extradition. Receiving Money Knowing It to Have Been Fraudulently Obtained

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History, update, and the baby boom of elephants in 1987 at the Zoological Center, Ramat-Gan, Israel

The Zoological Center, Tel-Aviv Ramat-Gan, Israel, has one of the largest breeding herds of African elephants in captivity. It also has a respectable breeding herd of Asian elephants. At peak population, there was a ponderous total of thirteen African and six Asian elephants in our zoo. Of these, six individuals were bom in 1987. In this article I will describe the background of our herds, the animal quarters, and provide some of our interesting observations on the relationships between the newborn and their relatives, bringing the review up to date, 1998

Forces Sauces and Eggs for Soldiers: food, nostalgia, and the rehabilitation of the British military

This article identifies, and considers the political implications of, the association of the contemporary British military and British soldiers with nostalgia. This aspect of the discursive project of rehabilitating the British military post-Iraq has not hitherto been theorized. The article analyses a set of exemplifying texts, four military charity food brands (Eggs for Soldiers, Forces Sauces, Red Lion Foods, and Rare Tea Company Battle of Britain Tea) to ask how nostalgic rehabilitation of the British military unfolds at the intersections of militarization, commemoration, and post-2008 “conscience capitalism”. I outline how military charity food brands are a form of “conscience capitalism” through which the perpetuation of militarized logics are produced as a notionally apolitical social “cause”, rendered intelligible within the terms of existing commoditized discourses of post-2008 vintage nostalgia. I then ask what understandings of British soldiers and the British military are constituted within the discourse of nostalgic rehabilitation, and secondly what forms of commemoration are entailed. I argue that a nostalgic generalization of soldiers and the military nullifies the potential unruliness of individual soldiers and obscures the specifics of recent, controversial, wars. Secondly nostalgic civil–military engagement entails a commemorative logic in which forms of quasi-military service are brought into the most banal spaces of everyday civilian life