A Prospective Multicenter SPOG 2003 FN Study of Microbiologically Defined Infections in Pediatric Cancer Patients with Fever and Neutropenia.

BACKGROUND: Fever and neutropenia (FN) often complicate anticancer treatment and can be caused by potentially fatal infections. Knowledge of pathogen distribution is paramount for optimal patient management. METHODS: Microbiologically defined infections (MDI) in pediatric cancer patients presenting with FN by nonmyeloablative chemotherapy enrolled in a prospective multi-center study were analyzed. Effectiveness of empiric antibiotic therapy in FN episodes with bacteremia was assessed taking into consideration recently published treatment guidelines for pediatric patients with FN. RESULTS: MDI were identified in a minority (22%) of pediatric cancer patients with FN. In patients with, compared to without MDI, fever (median, 5 [IQR 3-8] vs. 2 [IQR1-3] days, p < 0.001) and hospitalization (10 [6-14] vs. 5 [3-8] days, p < 0.001) lasted longer, transfer to the intensive care unit was more likely (13 of 95 [14%] vs. 7 of 346 [2.0%], p < 0.001), and antibiotics were given longer (10 [7-14] vs. 5 [4-7], p < 0.001). Empiric antibiotic therapy in FN episodes with bacteremia was highly effective if not only intrinsic and reported antimicrobial susceptibilities were considered but the purposeful omission of coverage for coagulase negative staphylococci and enterococci was also taken into account (81% [95%CI 68 - 90] vs. 96.6% [95%CI 87 - 99.4], p = 0.004) CONCLUSIONS: MDI were identified in a minority of FN episodes but they significantly affected management and the clinical course of pediatric cancer patients. Compliance with published guidelines was associated with effectiveness of empiric antibiotic therapy in FN episodes with bacteremia.

Uncertainty Quantification with Support Vector Regression Prediction Models

Uncertainty quantification of petroleum reservoir models is one of the present challenges, which is usually approached with a wide range of geostatistical tools linked with statistical optimisation or/and inference algorithms. The paper considers a data driven approach in modelling uncertainty in spatial predictions. Proposed semi-supervised Support Vector Regression (SVR) model has demonstrated its capability to represent realistic features and describe stochastic variability and non-uniqueness of spatial properties. It is able to capture and preserve key spatial dependencies such as connectivity, which is often difficult to achieve with two-point geostatistical models. Semi-supervised SVR is designed to integrate various kinds of conditioning data and learn dependences from them. A stochastic semi-supervised SVR model is integrated into a Bayesian framework to quantify uncertainty with multiple models fitted to dynamic observations. The developed approach is illustrated with a reservoir case study. The resulting probabilistic production forecasts are described by uncertainty envelopes.

Biological control of soil-borne pathogens by fluorescent pseudomonads.

Particular bacterial strains in certain natural environments prevent infectious diseases of plant roots. How these bacteria achieve this protection from pathogenic fungi has been analysed in detail in biocontrol strains of fluorescent pseudomonads. During root colonization, these bacteria produce antifungal antibiotics, elicit induced systemic resistance in the host plant or interfere specifically with fungal pathogenicity factors. Before engaging in these activities, biocontrol bacteria go through several regulatory processes at the transcriptional and post-transcriptional levels.

Utility of beta-glucan for the diagnosis of invasive fungal infections

(1,3)-b-D-glucan is a component of the fungal cell wall. New assays have made it possible to detect this molecule in a variety of clinical samples such as blood, cerebrospinal fluid, and bronchioalveolar lavage fluid. Detection of this molecule through several assays has been validated as an adjunct method to diagnose invasive fungal infections. With several decades of data and recent positive meta-analyses, these assays have now been sufficiently studied and are ready to enter the mainstream of diagnosis in medical mycology.

Decrease in the prevalence of hepatitis B and a low prevalence of hepatitis C virus infections in the general population of the Seychelles.

A serological survey of hepatitis B virus (HBV) and hepatitis C virus (HCV) infections was carried out on a random sex- and age-stratified sample of 1006 individuals aged 25-64 years in the Seychelles islands. Anti-HBc and anti-HCV antibodies were detected using commercially available enzyme-linked immunosorbent assays (ELISA), followed by a Western blot assay in the case of a positive result for anti-HCV. The age-adjusted seroprevalence of anti-HBc antibodies was 8.0% (95% CI: 6.5-9.9%) and the percentage prevalence among males/females increased from 7.0/3.1 to 19.1/13.4 in the age groups 25-34 to 55-64 years, respectively. Two men and three women were positive for anti-HCV antibodies, with an age-adjusted seroprevalence of 0.34% (95% CI: 0.1-0.8%). Two out of these five subjects who were positive for anti-HCV also had anti-HBc antibodies. The seroprevalence of anti-HBc was significantly higher in unskilled workers, persons with low education, and heavy drinkers. The age-specific seroprevalence of anti-HBc in this population-based survey, which was conducted in 1994, was approximately three times lower than in a previous patient-based survey carried out in 1979. Although there are methodological differences between the two surveys, it is likely that the substantial decrease in anti-HBc prevalence during the last 15 years may be due to significant socioeconomic development and the systematic screening of blood donors since 1981. Because hepatitis C virus infections are serious and the cost of treatment is high, the fact that the prevalence of anti-HCV antibodies is at present low should not be an argument for not screening blood donors for anti-HCV and eliminating those who are positive.

Discovery of novel arenavirus receptors and entry factors

Arenaviruses are enveloped negative-strand RNA viruses that contain a bi-segmented genome. They are rodent-borne pathogens endemic to the Americas and Africa, with the exception of lymphocytic choriomeningitis virus (LCMV) that is world-wide distributed. The arenaviruses include numerous important human pathogens including the Old World arenavirus Lassa virus (LASV), the causative agent of a severe viral hemorrhagic fever in humans with several hundred thousand infections per year in Africa and thousands of deaths. Viruses are obligatory intracellular parasites, strictly depending on cellular processes and factors to complete their replication cycle. The binding of a virus to target cells is the first step of every viral infection, and is mainly mediated by viral proteins that can directly engage cellular receptors, providing a key determinant for viral tropism. This early step of infection represents a promising target to block the pathogen before it can take control over the host cell. Old World arenaviruses, such as LASV and LCMV, bind to host cells via attachment to their main receptor, dystroglycan (DG), an ubiquitous receptor for extracellular matrix proteins. The engagement of DG by LASV results in a fast internalization and transfer the virus to late endosomal compartment suggesting that the virus binding to DG causes marked changes in the dynamics of the receptor. These events could result in the clustering of the receptor and subsequent induction of signaling that could be modulated by the virus. Recently, numerous findings also suggest the presence of alternative receptor(s) for LASV in absence of the main DG receptor. In my first project, I was interested to investigate the effects of virus-receptor binding on the tyrosine phosphorylation of the cytoplasmic domain of DG and to test if this post-translational modification was crucial for the internalization of the LASV-receptor complex. We found that engagement of cellular DG by a recombinant LCMV expressing the envelope GP of LASV in human epithelial cells induced tyrosine phosphorylation of the cytoplasmic domain of DG. LASV GP binding to DG further resulted in dissociation of the adapter protein utrophin from virus-bound DG. Virus-induced dissociation of utrophin and consequent virus internalization were affected by the broadly specific tyrosine kinase inhibitor genistein. We speculate that the detachment of virus- bound DG from the actin-based cytoskeleton following DG phosphorylation may facilitate subsequent endocytosis of the virus-receptor complex. In the second project, I was interested to characterize the newly indentified LASV alternative receptor Axl in the context of productive arenavirus infection. In a first step, we demonstrated that Axl supports productive infection by rLCMV-LASVGP in a DG-independent manner. In line with previous studies, cell entry of rLCMV-LASVGP via Axl was less efficient when compared to functional DG. Interestingly, Axl-mediated infection showed rapid kinetics similar to DG-dependent entry. Using a panel of inhibitors, we found that Axl-mediated cell entry of rLCMV-LASVGP involved a clathrin-independent pathway that critically depended on actin and dynamin and was sensitive to EIPA but not to PAK inhibitors, compatible with a macropinocytosis-like mechanism of entry. In a next step, we aimed to investigate the molecular mechanism by which rLCMV-LASVGP recognizes Axl. Phosphatidylserine (PS) is the natural ligand of Axl via the adaptor protein Gas6. We detected the presence of PS in the envelope of Old World arenaviruses, suggesting that PS could mediate Axl-virus binding, in a mechanism of apoptotic mimicry already described for other viruses. Whether envelope PS and/or the GP of LASV plays any role in virus entry via Axl is still an open question. The molecular mechanisms underlying host cell-virus interaction are of particular interest to answer basic scientific questions as well as to apply key findings to translational research. Understanding pathogen induced-signaling and its link to invasion of the host cell is of great importance to develop drugs for therapeutic intervention against highly pathogenic viruses like LASV. - Les Arenavirus sont des virus enveloppés à ARN négatifs organisés sous forme de génome bisegmenté. Ils sont véhiculés par les rongeurs et se retrouvent de manière endémique aux Amériques et en Afrique avec l'exception du virus de la chorioméningite lymphocytaire (LCMV) qui lui est distribué mondialement. De nombreux pathogènes humains font parti de la famille des Arenavirus dont le virus de l'Ancien Monde Lassa (LASV), un agent responsable de fièvres hémorragiques sévères chez les humains. Le virus de Lassa cause plusieurs centaines de milliers d'infections par année en Afrique ainsi que des milliers de morts. De manière générale, les virus sont des parasites intracellulaires obligatoires qui dépendent strictement de processus et facteurs cellulaires pour clore leur cycle de réplication. L'attachement d'un virus à sa cellule cible représente la première étape de chaque infection virale et est principalement dirigée par des protéines virales qui interagissent directement avec leur récepteurs cellulaires respectifs fournissant ainsi un indicateur déterminant pour le tropisme d'un virus. Cette première étape de l'infection représente aussi une cible prometteuse pour bloquer le pathogène avant qu'il ne puisse prendre le contrôle de la cellule. Les Arenavirus de l'Ancien Monde comme LASV et LCMV s'attachent à la cellule hôte en se liant à leur récepteur principal, le dystroglycan (DG), un récepteur ubiquitaire pour les protéines de la matrice extracellulaire. La liaison du DG par LASV résulte en une rapide internalisation transférant le virus aux endosomes tardifs suggérant ainsi que l'attachement du virus au DG peut provoquer des changements marqués dans la dynamique moléculaire du récepteur. Ces événements sont susceptibles d'induire un regroupement du récepteur à la surface cellulaire, ainsi qu'une induction subséquente qui pourrait être, par la suite, modulée par le virus. Récemment, plusieurs découvertes suggèrent aussi la présence d'un récepteur alternatif pour LASV en l'absence du récepteur principal, le DG. Concernant mon premier projet, j'étais intéressée à étudier les effets de la liaison virus- récepteur sur la phosphorylation des acides aminés tyrosines se trouvant dans la partie cytoplasmique du DG, le but étant de tester si cette modification post-translationnelle était cruciale pour Γ internalisation du complexe LASV-DG récepteur. Nous avons découvert que l'engagement du récepteur DG par le virus recombinant LCMV, exprimant la glycoprotéine de LASV, dans des cellules épithéliales humaines induit une phosphorylation de résidu(s) tyrosine se situant dans le domaine cytoplasmique du DG. La liaison de la glycoprotéine de LASV au DG induit par la suite la dissociation de la protéine adaptatrice utrophine du complexe virus-DG récepteur. Nous avons observé que cette dissociation de l'utrophine, induite par le virus, ainsi que son internalisation, sont affectées par l'inhibiteur à large spectre des tyrosines kinases, la génistéine. Nous avons donc supposé que le détachement du virus, lié au récepteur DG, du cytosquelette d'actine suite à la phosphorylation du DG faciliterait l'endocytose subséquente du complexe virus-récepteur. Dans le second projet, j'étais intéressée à caractériser le récepteur alternatif Axl qui a été récemment identifié dans le contexte de l'infection productive des Arenavirus. Dans un premier temps, nous avons démontré que le récepteur alternatif Axl permet l'infection des cellules par le virus LCMV recombinant LASV indépendamment du récepteur DG. Conformément aux études publiées précédemment, nous avons pu observer que l'entrée du virus recombinant LASV via Axl est moins efficace que via le récepteur principal DG. De façon intéressante, nous avons aussi remarqué que l'infection autorisée par Axl manifeste une cinétique virale d'entrée similaire à celle observée avec le récepteur DG. Utilisant un éventail de différents inhibiteurs, nous avons trouvé que l'entrée du virus recombinant rLCMV-LASVGP via Axl implique une voie d'entrée indépendante de la clathrine et dépendant de manière critique de l'actine et de la dynamine. Cette nouvelle voie d'entrée est aussi sensible à l'EIPA contrairement aux inhibiteurs PAK indiquant un mécanisme d'entrée compatible avec un mécanisme de macropinocytose. L'étape suivante du projet a été d'investiguer le mécanisme moléculaire par lequel le virus recombinant rLCMV-LASVGP reconnaît le récepteur alternatif Axl. La phosphatidylsérine (PS) se trouve être un ligand naturel pour Axl via la protéine adaptatrice Gas6. Nous avons détecté la présence de PS dans l'enveloppe des Arenavirus du Vieux Monde suggérant que la PS pourrait médier la liaison du virus à Axl dans un mécanisme de mimétisme apoptotique déjà observé et décrit pour d'autres virus. Cependant, il reste encore à déterminer qui de la PS ou de la glycoprotéine de l'enveloppe virale intervient dans le processus d'entrée de LASV via le récepteur alternatif Axl. Les mécanismes moléculaires à la base de l'interaction entre virus et cellule hôte sont d'intérêts particuliers pour répondre aux questions scientifiques de base ainsi que dans l'application de découvertes clés pour la recherche translationnelle. La compréhension de la signalisation induite par les pathogènes ainsi que son lien à l'invasion de la cellule hôte est d'une importance considérable pour le développement de drogues pour l'intervention thérapeutique contre les virus hautement pathogènes comme LASV.

The course of malaria in mice: major histocompatibility complex (MHC) effects, but no general MHC heterozygote advantage in single-strain infections.

A general MHC-heterozygote advantage in parasite-infected organisms is often assumed, although there is little experimental evidence for this. We tested the response of MHC-congenic mice (F2 segregants) to malaria and found the course of infection to be significantly influenced by MHC haplotype, parasite strain, and host gender. However, the MHC heterozygotes did worse than expected from the average response of the homozygotes.

The dynamic adjustment of local government budgets : Does Spain behave differently?

[spa] El objetivo de este trabajo es analizar si los municipios españoles se ajustan en presencia de un shock presupuestario y (si es así) qué elementos del presupuesto son los que realizan el ajuste. La metodología utilizada para contestar estas preguntas es un mecanismo de corrección del error, VECM, que estimamos con un panel de datos de los municipios españoles durante el período 1988-2006. Nuestros resultados confirman que, en primer lugar, los municipios se ajustan en presencia de un shock fiscal (es decir, el déficit es estacionario en el largo plazo). En segundo lugar, obtenemos que cuando el shock afecta a los ingresos el ajuste lo soporta principalmente el municipio reduciendo el gasto, las transferencias tienen un papel muy reducido en este proceso de ajuste. Por el contrario, cuando el shock afecta al gasto, el ajuste es compartido en términos similares entre el municipio – incrementado los impuestos – y los gobiernos de niveles superiores – incrementando las transferencias. Estos resultados sugieren que la viabilidad de las finanzas pública locales es factible con diferentes entornos institucionales.

Use of human MAR elements to improve retroviral vector production.

Retroviral vectors have many favorable properties for gene therapies, but their use remains limited by safety concerns and/or by relatively lower titers for some of the safer self-inactivating (SIN) derivatives. In this study, we evaluated whether increased production of SIN retroviral vectors can be achieved from the use of matrix attachment region (MAR) epigenetic regulators. Two MAR elements of human origin were found to increase and to stabilize the expression of the green fluorescent protein transgene in stably transfected HEK-293 packaging cells. Introduction of one of these MAR elements in retroviral vector-producing plasmids yielded higher expression of the viral vector RNA. Consistently, viral titers obtained from transient transfection of MAR-containing plasmids were increased up to sixfold as compared with the parental construct, when evaluated in different packaging cell systems and transfection conditions. Thus, use of MAR elements opens new perspectives for the efficient generation of gene therapy vectors.