Biofilm formation at the solid-liquid and air-liquid interfaces by Acinetobacter species

Abstract Background: The members of the genus Acinetobacter are Gram-negative cocobacilli that are frequently found in the environment but also in the hospital setting where they have been associated with outbreaks of nosocomial infections. Among them, Acinetobacter baumannii has emerged as the most common pathogenic species involved in hospital-acquired infections. One reason for this emergence may be its persistence in the hospital wards, in particular in the intensive care unit; this persistence could be partially explained by the capacity of these microorganisms to form biofilm. Therefore, our main objective was to study the prevalence of the two main types of biofilm formed by the most relevant Acinetobacter species, comparing biofilm formation between the different species. Findings: Biofilm formation at the air-liquid and solid-liquid interfaces was investigated in different Acinetobacter spp. and it appeared to be generally more important at 25°C than at 37°C. The biofilm formation at the solid-liquid interface by the members of the ACB-complex was at least 3 times higher than the other species (80-91% versus 5-24%). In addition, only the isolates belonging to this complex were able to form biofilm at the air-liquid interface; between 9% and 36% of the tested isolates formed this type of pellicle. Finally, within the ACB-complex, the biofilm formed at the air-liquid interface was almost 4 times higher for A. baumannii and Acinetobacter G13TU than for Acinetobacter G3 (36%, 27% & 9% respectively). Conclusions: Overall, this study has shown the capacity of the Acinetobacter spp to form two different types of biofilm: solid-liquid and air-liquid interfaces. This ability was generally higher at 25°C which might contribute to their persistence in the inanimate hospital environment. Our work has also demonstrated for the first time the ability of the members of the ACB-complex to form biofilm at the air-liquid interface, a feature that was not observed in other Acinetobacter species

Small Hairy Black Holes in Global AdS Spacetime

We study small charged black holes in global AdS spacetime in the presence of a charged massless minimally coupled scalar field. In a certain parameter range these black holes suffer from well known superradiant instabilities. We demonstrate that the end point of the resultant tachyon condensation process is a hairy black hole which we construct analytically in a perturbative expansion in the black hole radius. At leading order our solution is a small undeformed RNAdS black hole immersed into a charged scalar condensate that fills the AdS `box'. These hairy black hole solutions appear in a two parameter family labelled by their mass and charge. Their mass is bounded from below by a function of their charge; at the lower bound a hairy black hole reduces to a regular horizon free soliton which can also be thought of as a nonlinear Bose condensate. We compute the microcanonical phase diagram of our system at small mass, and demonstrate that it exhibits a second order `phase transition' between the RNAdS black hole and the hairy black hole phases.Comment: 68+1 pages, 18 figures, JHEP format. v2 : small typos corrected and a reference adde

Mechanical Strength of 17 134 Model Proteins and Cysteine Slipknots

A new theoretical survey of proteins' resistance to constant speed stretching is performed for a set of 17 134 proteins as described by a structure-based model. The proteins selected have no gaps in their structure determination and consist of no more than 250 amino acids. Our previous studies have dealt with 7510 proteins of no more than 150 amino acids. The proteins are ranked according to the strength of the resistance. Most of the predicted top-strength proteins have not yet been studied experimentally. Architectures and folds which are likely to yield large forces are identified. New types of potent force clamps are discovered. They involve disulphide bridges and, in particular, cysteine slipknots. An effective energy parameter of the model is estimated by comparing the theoretical data on characteristic forces to the corresponding experimental values combined with an extrapolation of the theoretical data to the experimental pulling speeds. These studies provide guidance for future experiments on single molecule manipulation and should lead to selection of proteins for applications. A new class of proteins, involving cystein slipknots, is identified as one that is expected to lead to the strongest force clamps known. This class is characterized through molecular dynamics simulations.Comment: 40 pages, 13 PostScript figure

Size and surface charge of gold nanoparticles determine absorption across intestinal barriers and accumulation in secondary target organs after oral administration

It is of urgent need to identify the exact physico-chemical characteristics which allow maximum uptake and accumulation in secondary target organs of nanoparticulate drug delivery systems after oral ingestion. We administered radiolabelled gold nanoparticles in different sizes (1.4-200 nm) with negative surface charge and 2.8 nm nanoparticles with opposite surface charges by intra-oesophageal instillation into healthy adult female rats. The quantitative amount of the particles in organs, tissues and excrements was measured after 24 h by gamma-spectroscopy. The highest accumulation in secondary organs was mostly found for 1.4 nm particles; the negatively charged particles were accumulated mostly more than positively charged particles. Importantly, 18 nm particles show a higher accumulation in brain and heart compared to other sized particles. No general rule accumulation can be made so far. Therefore, specialized drug delivery systems via the oral route have to be individually designed, depending on the respective target organ

The priming effect of extracellular UTP on human neutrophils: Role of calcium released from thapsigargin-sensitive intracellular stores

P2Y2 receptors, which are equally responsive to ATP and UTP, can trigger intracellular signaling events, such as intracellular calcium mobilization and mitogen-activated protein (MAP) kinase phosphorylation in polymorphonuclear leukocytes (PMN). Moreover, extracellular nucleotides have been shown to prime chemoattractant-induced superoxide production. The aim of our study was to investigate the mechanism responsible for the priming effect of extracellular nucleotides on reactive oxygen species (ROS) production induced in human neutrophils by two different chemoattractants: formyl-methionyl-leucyl-phenylalanine (fMLP) and interleukin-8 (IL-8). Nucleotide-induced priming of ROS production was concentration- and time-dependent. When UTP was added to neutrophil suspensions prior to chemoattractant, the increase of the response reached the maximum at 1 min of pre-incubation with the nucleotide. UTP potentiated the phosphorylation of p44/42 and p38 MAP kinases induced by chemoattractants, however the P2 receptor-mediated potentiation of ROS production was still detectable in the presence of a SB203580 or U0126, supporting the view that MAP kinases do not play a major role in regulating the nucleotide-induced effect. In the presence of thapsigargin, an inhibitor of the ubiquitous sarco-endoplasmic reticulum Ca2+-ATPases in mammalian cells, the effect of fMLP was not affected, but UTP-induced priming was abolished, suggesting that the release of calcium from thapsigargin-sensitive intracellular stores is essential for nucleotide-induced priming in human neutrophils

Description and consequences of sexual violence in Ituri province, Democratic Republic of Congo

ABSTRACT: BACKGROUND: The war in eastern Democratic Republic of Congo has been the subject of numerous studies related to the problem of sexual violence. Historically, such violence is known to be part of strategic war plans to conquer and destroy communities, but it is now unfortunately prevalent in times of relative calm. METHODS: We describe the characteristics and consequences of sexual violence in Ituri province of Democratic Republic of Congo through the retrospective analysis of 2,565 patients who received medical care in the Medecins Sans Frontieres sexual violence clinic in the capital of Ituri province, Bunia, between September 2005 and December 2006. Using a standardised questionnaire, we report patients' demographics, number and status of aggressor(s), forced detention and violent threats among other variables for all patients presenting for medical consultation after a sexually violent event during this period. RESULTS: Ninety-six percent of our cohort were female and 29.3% minors, 18-29 years was the most represented age group. Acts of sexual violence (n= 2,565) were reported to be mainly perpetrated by men with military affiliations (73%), although civilians were implicated in 21% of crimes. The attack was perpetrated by two or more persons in over 74% of cases and most commonly perpetrators were unknown armed males, (87.2%). Male victims accounted for 4% (n=103) of our cohort. Forty-eight percent of our patients reported being attacked whilst performing daily domestic duties outside the home and 18% of victims being detained by their perpetrators, the majority of whom were held for less than 2 weeks (61.6%). CONCLUSIONS: The characteristics of sexually violent acts in Ituri province during this period cannot be simply explained as a 'weapon of war' as described in the literature, meaning the use of sexual violence within a military strategy where it is employed under the orders of a commander to harm a particular community. Whilst the majority of aggressions were by armed men there was an important proportion in which civilian perpetrators were implicated. This type of violence has become part of the general characteristics of violence in this war-torn population. Sometimes, as a means for some military factions to acquire remuneration with impunity and for some civilians, a means to counteract confronting, changing social norms occurring during chronic conflict

Diseases of the salivary glands in infants and adolescents

<p>Abstract</p> <p>Background</p> <p>Diseases of the salivary glands are rare in infants and children (with the exception of diseases such as parotitis epidemica and cytomegaly) and the therapeutic regimen differs from that in adults. It is therefore all the more important to gain exact and extensive insight into general and special aspects of pathological changes of the salivary glands in these age groups. Etiology and pathogenesis of these entities is still not yet fully known for the age group in question so that general rules for treatment, based on clinical experience, cannot be given, particularly in view of the small number of cases of the different diseases. Swellings of the salivary glands may be caused by acute and chronic inflammatory processes, by autoimmune diseases, by duct translocation due to sialolithiasis, and by tumors of varying dignity. Clinical examination and diagnosis has also to differentiate between salivary gland cysts and inflammation or tumors.</p> <p>Conclusion</p> <p>Salivary gland diseases are rare in childhood and adolescence. Their pattern of incidence differs very much from that of adults. Acute and chronic sialadenitis not responding to conservative treatment requires an appropriate surgical approach. The rareness of salivary gland tumors is particularly true for the malignant parotid tumors which are more frequent in juvenile patients, a fact that has to be considered in diagnosis and therapy.</p

f(R) theories

Over the past decade, f(R) theories have been extensively studied as one of the simplest modifications to General Relativity. In this article we review various applications of f(R) theories to cosmology and gravity - such as inflation, dark energy, local gravity constraints, cosmological perturbations, and spherically symmetric solutions in weak and strong gravitational backgrounds. We present a number of ways to distinguish those theories from General Relativity observationally and experimentally. We also discuss the extension to other modified gravity theories such as Brans-Dicke theory and Gauss-Bonnet gravity, and address models that can satisfy both cosmological and local gravity constraints.Comment: 156 pages, 14 figures, Invited review article in Living Reviews in Relativity, Published version, Comments are welcom

All-inkjet-printed thin-film transistors: manufacturing process reliability by root cause analysis

We report on the detailed electrical investigation of all-inkjet-printed thin-film transistor (TFT) arrays focusing on TFT failures and their origins. The TFT arrays were manufactured on flexible polymer substrates in ambient condition without the need for cleanroom environment or inert atmosphere and at a maximum temperature of 150 degrees C. Alternative manufacturing processes for electronic devices such as inkjet printing suffer from lower accuracy compared to traditional microelectronic manufacturing methods. Furthermore, usually printing methods do not allow the manufacturing of electronic devices with high yield (high number of functional devices). In general, the manufacturing yield is much lower compared to the established conventional manufacturing methods based on lithography. Thus, the focus of this contribution is set on a comprehensive analysis of defective TFTs printed by inkjet technology. Based on root cause analysis, we present the defects by developing failure categories and discuss the reasons for the defects. This procedure identifies failure origins and allows the optimization of the manufacturing resulting finally to a yield improvement