A flea-induced pre-hatching maternal effect modulates tick feeding behaviour on great tit nestlings

1. A host's defence reaction against one parasite species can modulate the habitat quality for other parasites in two ways: it can provide cross-resistance against closely related species due to antigenic similarity, or it can reduce resistance to other cohabiting species, since the mounting of multiple defence reactions is more costly. 2. Here we test whether two completely unrelated parasite species can influence each other across host generations, that is, whether a hen flea-induced maternal effect known to protect great tit (Parus major) nestlings against flea infestations will also alter tick (Ixodes ricinus) feeding behaviour on nestlings. 3. We infested experimental great tit nests with hen fleas (Ceratophyllus gallinae) prior to egg-laying to induce the maternal effect, while all parasites were removed in control nests. Nestlings from the two types of nests were then cross-fostered into flea-free foster nests to produce broods that contained both, nestlings with and without the flea-induced maternal effect. Five days after hatching, we put five larval ticks on each nestling and assessed tick feeding behaviour. 4. We found that ticks feeding on nestlings with the flea-induced maternal effect detached significantly earlier than ticks feeding on controls. The result is compatible with the hypothesis of a trans-generational parasite–parasite interaction, that is, it suggests that the flea-induced maternal effect alters tick feeding behaviour and that it may protect nestlings against tick-borne diseases by reducing tick attachment times. In addition, we found that more ticks attached on male than on female nestlings, suggesting that males are more susceptible to parasites than females as shown in other vertebrates

Characterization of the a-Si EPID in the unity MR-linac for dosimetric applications

Abstract Electronic portal imaging devices (EPIDs) are frequently used in external beam radiation therapy for dose verification purposes. The aim of this study was to investigate the dose-response characteristics of the EPID in the Unity MR-linac (Elekta AB, Stockholm, Sweden) relevant for dosimetric applications under clinical conditions. EPID images and ionization chamber (IC) measurements were used to study the effects of the magnetic field, the scatter generated in the MR housing reaching the EPID, and inhomogeneous attenuation from the MR housing. Dose linearity and dose rate dependencies were also determined. The magnetic field strength at EPID level did not exceed 10 mT, and dose linearity and dose ratedependencies proved to be comparable to that on a conventional linac. Profiles of fields, delivered with and without the magnetic field, were indistinguishable. The EPID center had an offset of 5.6 cm in the longitudinal direction, compared to the beam central axis, meaning that large fields in this direction will partially fall outside the detector area and not be suitable for verification. Beam attenuation by the MRI scanner and the table is gantry angle dependent, presenting a minimum attenuation of 67% relative to the 90° measurement. Repeatability, observed over two months, was within 0.5% (1 SD). In order to use the EPID for dosimetric applications in the MR-linac, challenges related to theEPID position, scatter from the MR housing, and the inhomogeneous, gantry angle-dependent attenuation of the beam will need to be solved.Biological, physical and clinical aspects of cancer treatment with ionising radiatio

A multidisciplinary method to map potential tuberculosis transmission 'hot spots' in high-burden communities

BACKGROUND: Global control of the tuberculosis (TB) epidemic remains poor, especially in high-burden settings where ongoing transmission sustains the epidemic. In such settings, a significant amount of transmission takes place outside the household, and practical approaches to understanding transmission at community level are needed. OBJECTIVE: To identify and map potential TB transmission 'hot spots' across high-burden communities. SETTING AND DESIGN: Our method draws on data that qualitatively describe a high-burden community in Cape Town, South Africa. Established transmission principles are applied to grade the potential TB transmission risk posed by congregate settings in the community. Geographic information systems (GIS) technology then creates a visual map, locating potential transmission 'hot spots' in the community. RESULTS: Drinking places (shebeens), clinics and churches (often gatherings in confined homes) emerge as gathering places that potentially pose a high transmission risk, particularly if located in overcrowded and impoverished areas of the community. CONCLUSION: This proof-of-concept study demonstrates that combining qualitative techniques with GIS mapping may improve our understanding of potential TB transmission within a community and guide public health interventions to enhance TB control efforts. © 2009 The Union.Articl

A back-projection algorithm in the presence of an extra attenuating medium: towards EPID dosimetry for the MR-Linac

In external beam radiotherapy, electronic portal imaging devices (EPIDs) are frequently used for pre-treatment and for in vivo dose verification. Currently, various MR-guided radiotherapy systems are being developed and clinically implemented. Independent dosimetric verification is highly desirable. For this purpose we adapted our EPID-based dose verification system for use with the MR-Linac combination developed by Elekta in cooperation with UMC Utrecht and Philips. In this study we extended our back-projection method to cope with the presence of an extra attenuating medium between the patient and the EPID. Experiments were performed at a conventional linac, using an aluminum mock-up of the MRI scanner housing between the phantom and the EPID. For a 10 cm square field, the attenuation by the mock-up was 72%, while 16% of the remaining EPID signal resulted from scattered radiation. 58 IMRT fields were delivered to a 20 cm slab phantom with and without the mock-up. EPID reconstructed dose distributions were compared to planned dose distributions using the -evaluation method (global, 3%, 3 mm). In our adapted back-projection algorithm the averaged <img align="MIDDLE" alt="${{gamma}_{{ m mean}}}$ " src="http://cdn.iopscience.com/images/0031-9155/62/15/6322/pmbaa779eieqn002.gif" /> was , while in the conventional it was . Dose profiles of several square fields reconstructed with our adapted algorithm showed excellent agreement when compared to TPS.Biological, physical and clinical aspects of cancer treatment with ionising radiatio

Healthcare network modeling and analysis

Part 20: Health and Care NetworksInternational audienceA number of initiatives are nowadays in act to reorganize health systems and increase the interconnection of services offered to citizens to build a collaborative care network that maximizes service quality and minimizes costs. To achieve these purposes, a non standard quality assessment must be performed, as models for the analysis and evaluation of healthcare systems considered from the point of view of the entire network instead of single nodes have not been proposed yet. This paper aims at describing how to obtain a rigorous modeling and a meaningful analysis of the mass of data produced by a healthcare network. This analysis can be useful to inform the healthcare managers about the status of services under their responsibility and the degree of collaboration among entities of the network. The final outcome of these activities will be an improvement in the quality of service perceived by patients

Genotypic diversity in Babesia bovis field isolates and vaccine strains from South Africa

Genotypic diversity in Babesia bovis (cause of Asiatic redwater in cattle) vaccine strains and field isolates from South Africa were investigated using the Bv80 gene as well as microsatellites. The S11 vaccine strain possessed both A and B alleles of the Bv80 gene, as well as genotypic diversity within each allele type as defined by repeat variation resulting in different amplicon sizes. Rapid serial passage of vaccine strain from passage S10 to S24 resulted in loss of genotypic diversity that yielded a single allele A genotype with an amplicon size of 558 bp. This suggested that clonal selection occurred during rapid passaging. Extensive genotypic diversity exists in 44 field isolates characterized with both Bv80 A and B alleles, but can be readily distinguished from the S24 vaccine strain using either the Bv80 allele specific PCR assays or using multi-locus micro-satellite typing. This indicated that no recent documented clinical cases of Asiatic redwater were caused by the reversion to virulence of the current vaccine strain.Red Meat Research andDevelopment South Africa (Project: OV14/06/C226).http://www.elsevier.com/locate/vetparhb2016Veterinary Tropical Disease