42 research outputs found
Resonant interaction between gravitational waves, electromagnetic waves and plasma flows
In magnetized plasmas gravitational and electromagnetic waves may interact
coherently and exchange energy between themselves and with plasma flows. We
derive the wave interaction equations for these processes in the case of waves
propagating perpendicular or parallel to the plasma background magnetic field.
In the latter case, the electromagnetic waves are taken to be circularly
polarized waves of arbitrary amplitude. We allow for a background drift flow of
the plasma components which increases the number of possible evolution
scenarios. The interaction equations are solved analytically and the
characteristic time scales for conversion between gravitational and
electromagnetic waves are found. In particular, it is shown that in the
presence of a drift flow there are explosive instabilities resulting in the
generation of gravitational and electromagnetic waves. Conversely, we show that
energetic waves can interact to accelerate particles and thereby \emph{produce}
a drift flow. The relevance of these results for astrophysical and cosmological
plasmas is discussed.Comment: 12 pages, 1 figure, typos corrected and numerical example adde
Use of insecticide quantification kits to investigate the quality of spraying and decay rate of bendiocarb on different wall surfaces in Kagera region, Tanzania
Background
Bendiocarb was introduced for the first time for Indoor Residual Spraying (IRS) in Tanzania in 2012 as part of the interim national insecticide resistance management plan. This move followed reports of increasingly alarming levels of pyrethroid resistance across the country. This study used the insecticide quantification kit (IQK) to investigate the intra-operational IRS coverage and quality of spraying, and decay rate of bendiocarb on different wall surfaces in Kagera region.
Methods
To assess intra-operational IRS coverage and quality of spraying, 104 houses were randomly selected out of 161,414 sprayed houses. A total of 509 samples (218 in Muleba and 291 in Karagwe) were obtained by scraping the insecticide samples from wall surfaces. To investigate decay rate, 66 houses (36 in Muleba and 30 in Karagwe) were selected and samples were collected monthly for a period of five months. Laboratory testing of insecticide concentration was done using IQKTM [Innovative Vector Control Consortium].
Results
Of the 509 samples, 89.5% met the World Health Organization (WHO) recommended concentration (between 100ā400 mg/m2) for IRS target dosage. The proportion of samples meeting WHO standards varied between Karagwe (84.3%) and Muleba (96.3%) (pā<ā0.001). Assessment of quality of spraying at house level revealed that Muleba (84.8%) had a significantly higher proportion of households that met the expected target dosage (100ā400 mg/m2) compared to Karagwe (68.9%) (pā<ā0.001). The quality of spraying varied across different wall substrates in both districts. Evaluation of bendiocarb decay showed that the proportion of houses with recommended concentration declined from 96.9%, 93.5% and 76.2% at months one, two, and three post IRS, respectively (p-trendā=ā0.03). The rate of decay increased in the fourth and fifth month post spraying with only 55.9% and 26.3% houses meeting the WHO recommendations, respectively.
Conclusion
IQK is an important tool for assessing IRS coverage and quality of spraying. The study found adequate coverage of IRS; however, residual life of bendiocarb was observed to be three months. Results suggest that in order to maintain the recommended concentrations with bendiocarb, a second spray cycle should be carried out after three months
Ryanodine receptor point mutations confer diamide insecticide resistance in tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae).
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Insect ryanodine receptors (RyR) are the molecular target-site for the recently introduced diamide insecticides. Diamides are particularly active on Lepidoptera pests, including tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae). High levels of diamide resistance were recently described in some European populations of T. absoluta, however, the mechanisms of resistance remained unknown. In this study the molecular basis of diamide resistance was investigated in a diamide resistant strain from Italy (IT-GELA-SD4), and additional resistant field populations collected in Greece, Spain and Brazil. The genetics of resistance was investigated by reciprocally crossing strain IT-GELA-SD4 with a susceptible strain and revealed an autosomal incompletely recessive mode of inheritance. To investigate the possible role of target-site mutations as known from diamondback moth (Plutella xylostella), we sequenced respective domains of the RyR gene of T. absoluta. Genotyping of individuals of IT-GELA-SD4 and field-collected strains showing different levels of diamide resistance revealed the presence of G4903E and I4746M RyR target-site mutations. These amino acid substitutions correspond to those recently described for diamide resistant diamondback moth, i.e. G4946E and I4790M. We also detected two novel mutations, G4903V and I4746T, in some of the resistant T. absoluta strains. Radioligand binding studies with thoracic membrane preparations of the IT-GELA-SD4 strain provided functional evidence that these mutations alter the affinity of the RyR to diamides. In combination with previous work on P. xylostella our study highlights the importance of position G4903 (G4946 in P. xylostella) of the insect RyR in defining sensitivity to diamides. The discovery of diamide resistance mutations in T. absoluta populations of diverse geographic origin has serious implications for the efficacy of diamides under applied conditions. The implementation of appropriate resistance management strategies is strongly advised to delay the further spread of resistance.The work of Hellenic Agricultural Organisation - 'Demeter' was partially supported by an ARIMnet2 StomP grand to A.T and E.R. This work was also partially funded from a fellowship granted to H.A.A.S. (CNPq - PQ - Proc 308461/2013-4). The Universidad PolitĆ©cnica de Cartagena group would like to thank for partial financial support the Ministerio de EconomĆa y Competitividad of Spain and FEDER (AGL2011-25164). Lidia GarcĆa-Vidal holds a grant from the MECD (FPU13/01528). The Tuta absoluta strain from Gela, Sicily was collected under the frame a resistance monitoring program established among the Hellenic Agricultural Organisation - 'Demeter' and DuPont De Nemurs (data published in 2015). Finally, the Hellenic Agricultural Organisation - 'Demeter' would like to thank Fytochem S.A., Neo Mirtos, Ierapetra for supplies of plant material
Expression and Membrane Topology of Anopheles gambiae Odorant Receptors in Lepidopteran Insect Cells
A lepidopteran insect cell-based expression system has been employed to express three Anopheles gambiae odorant receptors (ORs), OR1 and OR2, which respond to components of human sweat, and OR7, the ortholog of Drosophila's OR83b, the heteromerization partner of all functional ORs in that system. With the aid of epitope tagging and specific antibodies, efficient expression of all ORs was demonstrated and intrinsic properties of the proteins were revealed. Moreover, analysis of the orientation of OR1 and OR2 on the cellular plasma membrane through the use of a novel ātopology screenā assay and FACS analysis demonstrates that, as was recently reported for the ORs in Drosophila melanogaster, mosquito ORs also have a topology different than their mammalian counterparts with their N-terminal ends located in the cytoplasm and their C-terminal ends facing outside the cell. These results set the stage for the production of mosquito ORs in quantities that should permit their detailed biochemical and structural characterization and the exploration of their functional properties
Comparative Genomics of the Anopheline Glutathione S-Transferase Epsilon Cluster
Enzymes of the glutathione S-transferase (GST) family play critical roles in detoxification of xenobiotics across many taxa. While GSTs are ubiquitous both in animals and plants, the GST epsilon class (GSTE) is insect-specific and has been associated with resistance to chemical insecticides. While both Aedes aegypti and Anopheles gambiae GSTE clusters consist of eight members, only four putative orthologs are identifiable between the species, suggesting independent expansions of the class in each lineage. We used a primer walking approach, sequencing almost the entire cluster from three Anopheles species (An. stephensi, An. funestus (both Cellia subgenus) and An. plumbeus (Anopheles subgenus)) and compared the sequences to putative orthologs in An. gambiae (Cellia) in an attempt to trace the evolution of the cluster within the subfamily Anophelinae. Furthermore, we measured transcript levels from the identified GSTE loci by real time reverse transcription PCR to determine if all genes were similarly transcribed at different life stages. Among the species investigated, gene order and orientation were similar with three exceptions: (i) GSTE1 was absent in An. plumbeus; (ii) GSTE2 is duplicated in An. plumbeus and (iii) an additional transcriptionally active pseudogene (ĻAsGSTE2) was found in An. stephensi. Further statistical analysis and protein modelling gave evidence for positive selection on codons of the catalytic site in GSTE5 albeit its origin seems to predate the introduction of chemical insecticides. Gene expression profiles revealed differences in expression pattern among genes at different life stages. With the exception of GSTE1, ĻAsGSTE2 and GSTE2b, all Anopheles species studied share orthologs and hence we assume that GSTE expansion generally predates radiation into subgenera, though the presence of GSTE1 may also suggest a recent duplication event in the Old World Cellia subgenus, instead of a secondary loss. The modifications of the catalytic site within GSTE5 may represent adaptations to new habitats
Use of insecticide quantification kits to investigate the quality of spraying and decay rate of bendiocarb on different wall surfaces in Kagera region, Tanzania
Evaluation of depression in patients with heart failure
Background: Despite advances in medical therapy heart failure consists a prevalent debilitating disease of poor prognosis, strongly associated with high mortality and morbidity rates. On the same time, depression rates are higher in patients with heart failure than in the general population. Depression may be underdiagnosed and consequently undertreated in the patients, as symptoms can often be similar in the two disease states. Purpose: The purpose of the present study was to explore the frequency of occurrence of depression in patients with heart failure and to evaluate possible precipitating factors. Method and material: Study sample consisted of 139 patients with heart failure, who were hospitalized or visited outpatients' clinics in two major hospitals in Athens. Collection of data was performed using the Zung Self-Rating Depression Scale. Statistical analyses (Student's t-test, One-way ANOVA) were conducted using the Statistical Package for Social Sciences 13.0 (SPSS, Chicago, Il, USA). Results: 110 patients (79.1%) were male and only 29 patients were female, over the age of 40. 71.9% were outpatients, 20.2% were hospitalized in the departments of cardiology, while 7.9% were I.C.U. patients. Analysis of data showed that 34.6% of patients scored lower than 40 in Zung Self-Rating Scale, indicating absence of depression, 27.3% scored 40 to 47, indicating mild depression, 20.9% scored 48 to 55, indicating moderate depression, and 17.2% scored over 56, indicating severe depression. More specifically, it was found that, regarding patients' gender and age, women (p=0.001) and patients over the age of 60 (p=0.001) experienced higher levels of depression, while regarding educational background patients who received only basic education may have been more prone to depression (p=0.05, non-significant). In addition, higher levels of depression were observed for those retired (p=0.028), those living in metropolitan areas (p=0.021), patients at 2 or 3 stage of heart failure (p<0.001), patients who had been diagnosed for over 1 year (p=0.032), as well as those who reported that were less informed about the extent of their condition (p=0.001). Conclusions: The majority of patients with heart failure experience various levels of depression. The main precipitating factors are age, gender, educational and economic status, place of residence, amount of receiving information as well as the stage and the onset of the disease. Nurses and physicians must act towards identification, assessment and management of depression in this clinical population
The HIV-1 gp120/V3 modifies the response of uninfected CD4 T cells to antigen presentation: mapping of the specific transcriptional signature
Background: The asymptomatic phase of HIV-1 infection is characterized by a progressive depletion of uninfected peripheral effector/memory CD4+ T cells that subsequently leads to immune dysfunction and AIDS symptoms. We have previously demonstrated that the presence of specific gp120/V3 peptides during antigen presentation can modify the activation of normal T-cells leading to altered immune function. The aim of the present study was to map the specific transcriptional profile invoked by an HIV-1/V3 epitope in uninfected T cells during antigen presentation. Methods: We exposed primary human peripheral blood monocytes to V3 lipopeptides using a liposome delivery system followed by a superantigen-mediated antigen presentation system. We then evaluated the changes in the T-cell transcriptional profile using oligonucleotide microarrays and performed Ingenuity Pathway Analysis (IPA) and DAVID analysis. The results were validated using realtime PCR, FACS, Western blotting and immunofluorescence. Results: Our results revealed that the most highly modulated transcripts could almost entirely be categorized as related to the cell cycle or transcriptional regulation. The most statistically significant enriched categories and networks identified by IPA were associated with cell cycle, gene expression, immune response, infection mechanisms, cellular growth, proliferation and antigen presentation. Canonical pathways involved in energy and cell cycle regulation, and in the co-activation of T cells were also enriched. Conclusions: Taken together, these results document a distinct transcriptional profile invoked by the HIV-1/V3 epitope. These data could be invaluable to determine the underlying mechanism by which HIV-1 epitopes interfere with uninfected CD4+ T-cell function causing hyper proliferation and AICD
Translation, adaptation and initial validation of Food Allergy Quality of Life Questionnaire: child form in Greek
The aim of the study is to determine the reliability and validity of the Greek version of the Food Allergy Quality of life Questionnaire- Child Form (FAQLQ-CF). After linguistic validation, the Greek FAQLQCF, Food Allergy Independent Measure (FAIM) and Pediatric Quality of Life Inventory (PedsQLā¢) were used by a physician to interview children diagnosed with food allergy and aged 8-12 via telephone. Cronbachās alpha was used to evaluate reliability, and factor analysis to assess construct validity. The correlation between FAQLQ-CF and FAIM was moderate (rho=0.509, P minimal clinical importance difference = 0.5; P<0.001), but not children differing in reporting anaphylaxis. The total FAQLQ-CF score correlated with the total PedsQLā¢ score and with the score of one of PedsQLā¢ subscales, demonstrating convergent validity. Factor analysis uncovered an underlying structure of four factors, explaining 50% of the variance. We can conclude that Greek FAQLQ-CF is a reliable, valid, discriminant tool for interviewing food allergic children aged 8- 12, detecting those in need for immediate care
Urease and Dental Plaque Microbial Profiles in Children
<div><p>Objective</p><p>Urease enzymes produced by oral bacteria generate ammonia, which can have a significant impact on the oral ecology and, consequently, on oral health. To evaluate the relationship of urease with dental plaque microbial profiles in children as it relates to dental caries, and to identify the main contributors to this activity.</p><p>Methods</p><p>82 supragingival plaque samples were collected from 44 children at baseline and one year later, as part of a longitudinal study on urease and caries in children. DNA was extracted; the V3āV5 region of the 16S rRNA gene was amplified and sequenced using 454 pyrosequencing. Urease activity was measured using a spectrophotometric assay. Data were analyzed with Qiime.</p><p>Results</p><p>Plaque urease activity was significantly associated with the composition of the microbial communities of the dental plaque (Baseline P = 0.027, One Year P = 0.012). The bacterial taxa whose proportion in dental plaque exhibited significant variation by plaque urease levels in both visits were the family Pasteurellaceae (Baseline P<0.001; One Year P = 0.0148), especially <i>Haemophilus parainfluenzae</i>. No association was observed between these bacteria and dental caries. Bacteria in the genus Leptotrichia were negatively associated with urease and positively associated with dental caries (Bonferroni P<0.001).</p><p>Conclusions</p><p>Alkali production by urease enzymes primarily from species in the family Pasteurellaceae can be an important ecological determinant in childrenās dental plaque. Further studies are needed to establish the role of urease-associated bacteria in the acid/base homeostasis of the dental plaque, and in the development and prediction of dental caries in children.</p></div