113 research outputs found
Experimental Passage of St. Louis Encephalitis Virus In Vivo in Mosquitoes and Chickens Reveals Evolutionarily Significant Virus Characteristics
St. Louis encephalitis virus (SLEV; Flaviviridae, flavivirus) was the major cause of epidemic flaviviral encephalitis in the U.S. prior to the introduction of West Nile virus (WNV) in 1999. However, outbreaks of SLEV have been significantly more limited then WNV in terms of levels of activity and geographic dispersal. One possible explanation for these variable levels of activity is that differences in the potential for each virus to adapt to its host cycle exist. The need for arboviruses to replicate in disparate hosts is thought to result in constraints on both evolution and host-specific adaptation. If cycling is the cause of genetic stability observed in nature and arboviruses lack host specialization, then sequential passage should result in both the accumulation of mutations and specialized viruses better suited for replication in that host. Previous studies suggest that WNV and SLEV differ in capacity for both genetic change and host specialization, and in the costs each accrues from specializing. In an attempt to clarify how selective pressures contribute to epidemiological patterns of WNV and SLEV, we evaluated mutant spectra size, consensus genetic change, and phenotypic changes for SLEV in vivo following 20 sequential passages via inoculation in either Culex pipiens mosquitoes or chickens. Results demonstrate that the capacity for genetic change is large for SLEV and that the size of the mutant spectrum is host-dependent using our passage methodology. Despite this, a general lack of consensus change resulted from passage in either host, a result that contrasts with the idea that constraints on evolution in nature result from host cycling alone. Results also suggest that a high level of adaptation to both hosts already exists, despite host cycling. A strain significantly more infectious in chickens did emerge from one lineage of chicken passage, yet other lineages and all mosquito passage strains did not display measurable host-specific fitness gains. In addition, increased infectivity in chickens did not decrease infectivity in mosquitoes, which further contrasts the concept of fitness trade-offs for arboviruses
The Lagrangian Loop Representation of Lattice U(1) Gauge Theory
It is showed how the Hamiltonian lattice can be cast
straightforwardly in the Lagrangian formalism. The procedure is general and
here we present the simplest case: pure compact QED. This connection has been
shaded by the non canonical character of the algebra of the fundamental loop
operators. The loops represent tubes of electric flux and can be considered the
dual objects to the Nielsen-Olesen strings supported by the Higgs broken phase.
The lattice loop classical action corresponding to the Villain form is
proportional to the quadratic area of the loop world sheets and thus it is
similar to the Nambu string action. This loop action is used in a Monte Carlo
simulation and its appealing features are discussed.Comment: 13 pp, UAB-FT-341/9
CA 125 regression after two cycles of neoadjuvant chemiotherapy as prognostic factor in patients with advanced ovarian cancer and primary peritoneal serous cancer who underwent interval surgical cytoreduction
Abstract Objectives: The aim of our study was to assess the prognostic role of CA 125 regression during neoadjuvant chemotherapy (NAC) in patients with ovarian cancer (OC) or primary peritoneal serous carcinoma (PPSC) that underwent interval debulking surgery (IOC). Material and methods: Thirty one patients with advanced OC or PPSC (FIGO stage IIIC and IV) who underwent initial exploratory surgery, followed by NAC containing platinum analogs, have been analyzed, retrospectively. We have used a regression coefficient (RCA 125), which was calculated as following: log10 (CA 125 level measured after two cycles of NAC/ baseline CA 125) for statistical analysis. The median value of RCA 125 reached -0.788 and has been used to dichotomize. Optimal IOC has been performed in 67.74% (21/31) patients, suboptimal in 25.81% (8/31) patients and 6.45% (2/31) of patients did not undergo IOC due to the progression of the disease. Results: We have noted significant correspondence between time to progression and RCA 125 in univariate analysis, which we have also confirmed in multivariate analysis (HR 0.27; 95%CI, 0.15-0.96; p=0.0118). Similarly, we have observed significant relationship between overall survival, RCA 125 and extension IOC in univariate analysis. Multivariate analysis confirmed that RCA 125 was independent prognostic factor, HR-0.18 (95%CI, 0.07-0.56; p=0.004). In case of patients with high RCA 125, a greater rate of optimal debulking cytoreduction (p=0.0278, U=50.0) has been observed. Conclusions: RCA 125 after two courses of NAC appears to be an important prognostic factor in patients with OC or PPSC, who underwent IOC. High RCA125 during NAC seems to be a good predictive factor in order to achieve optimal IOC
Comparison of the effects of TENS stimulation and water immersion on relieving labour pain suffered byprimiparas
Objectives: The aim of this study was to compare pain suffered by primiparas when delivering a child in a traditional way with deliveries where either TENS stimulation or water immersion was used.Material and methods: Primiparas were divided into 3 groups. In group 1 there were 45 women for whom TENS stimulation was applied during delivery. Group 2 consisted of 38 women who remained in the water during the actual birth of the baby. Group 3 served as the control group and was composed of 32 women. The intensity of pain during delivery was assessed by means of a numerical scale. During the first delivery period, pain was assessed three times at cervical dilation of 2, 3 and 4 fingers.Results: The analysis of pain suffered by primiparas at 2-finger widening showed no statistically significant differences between the groups. However, the analysis of pain experienced at 3-finger opening showed significant differences between the group of women using TENS stimulation in comparison with the control group. When comparing pain at 4-finger opening, statistically significant differences were found between the group of women who delivered in water in comparison to both the control group and the group using TENS stimulation.Conclusions: TENS stimulation and water immersion are good methods to relieve labour pain; particularly helpful in the first period of labour. They are also safe, alternative, non-pharmacological methods of reducing labour pain
West Nile Virus Genetic Diversity is Maintained during Transmission by Culex pipiens quinquefasciatus Mosquitoes
Due to error-prone replication, RNA viruses exist within hosts as a heterogeneous population of non-identical, but related viral variants. These populations may undergo bottlenecks during transmission that stochastically reduce variability leading to fitness declines. Such bottlenecks have been documented for several single-host RNA viruses, but their role in the population biology of obligate two-host viruses such as arthropod-borne viruses (arboviruses) in vivo is unclear, but of central importance in understanding arbovirus persistence and emergence. Therefore, we tracked the composition of West Nile virus (WNV; Flaviviridae, Flavivirus) populations during infection of the vector mosquito, Culex pipiens quinquefasciatus to determine whether WNV populations undergo bottlenecks during transmission by this host. Quantitative, qualitative and phylogenetic analyses of WNV sequences in mosquito midguts, hemolymph and saliva failed to document reductions in genetic diversity during mosquito infection. Further, migration analysis of individual viral variants revealed that while there was some evidence of compartmentalization, anatomical barriers do not impose genetic bottlenecks on WNV populations. Together, these data suggest that the complexity of WNV populations are not significantly diminished during the extrinsic incubation period of mosquitoes
Winter Bird Assemblages in Rural and Urban Environments: A National Survey
Urban development has a marked effect on the ecological and behavioural traits of many living
organisms, including birds. In this paper, we analysed differences in the numbers of wintering
birds between rural and urban areas in Poland. We also analysed species richness
and abundance in relation to longitude, latitude, human population size, and landscape
structure. All these parameters were analysed using modern statistical techniques incorporating
species detectability. We counted birds in 156 squares (0.25 km2 each) in December
2012 and again in January 2013 in locations in and around 26 urban areas across Poland
(in each urban area we surveyed 3 squares and 3 squares in nearby rural areas). The influence
of twelve potential environmental variables on species abundance and richness was
assessed with Generalized Linear Mixed Models, Principal Components and Detrended
Correspondence Analyses. Totals of 72 bird species and 89,710 individual birds were recorded
in this study. On average (±SE) 13.3 ± 0.3 species and 288 ± 14 individuals were recorded
in each square in each survey. A formal comparison of rural and urban areas
revealed that 27 species had a significant preference; 17 to rural areas and 10 to urban areas. Moreover, overall abundance in urban areas was more than double that of rural
areas. There was almost a complete separation of rural and urban bird communities. Significantly
more birds and more bird species were recorded in January compared to December.
We conclude that differences between rural and urban areas in terms of winter conditions
and the availability of resources are reflected in different bird communities in the two
environments
QCD corrections to scalar quark pair production in e+e- annihilation
We calculate the QCD radiative corrections to the production of
supersymmetric scalar partners of quarks in e+e- annihilation. We include both
the standard gluonic corrections and the genuine supersymmetric QCD corrections
due to quark--gluino loops, and allow for mixing between left-- and
right--handed scalar quarks which leads to the possibility that the two final
state particles have different masses. The corrections are found to be much
larger than the ones affecting the production of spin 1/2 particles.Comment: one typo corrected (2d paragraph of setion 5) and a better set of
figures has been included as an uuencoded compressed tar postscript fil
Spatial Overlap and Habitat Selection of Corvid Species in European Cities
Understanding habitat and spatial overlap in sympatric species of urban areas would aid in predicting species and community modifications in response to global change. Habitat overlap has been widely investigated for specialist species but neglected for generalists living in urban settings. Many corvid species are generalists and are adapted to urban areas. This work aimed to determine the urban habitat requirements and spatial overlap of five corvid species in sixteen European cities during the breeding season. All five studied corvid species had high overlap in their habitat selection while still having particular tendencies. We found three species, the Carrion/Hooded Crow, Rook, and Eurasian Magpie, selected open habitats. The Western Jackdaw avoided areas with bare soil cover, and the Eurasian Jay chose more forested areas. The species with similar habitat selection also had congruent spatial distributions. Our results indicate that although the corvids had some tendencies regarding habitat selection, as generalists, they still tolerated a wide range of urban habitats, which resulted in high overlap in their habitat niches and spatial distributions
Functional features of gene expression profiles differentiating gastrointestinal stromal tumours according to KIT mutations and expression
<p>Abstract</p> <p>Background</p> <p>Gastrointestinal stromal tumours (GISTs) represent a heterogeneous group of tumours of mesenchymal origin characterized by gain-of-function mutations in <it>KIT </it>or <it>PDGFRA </it>of the type III receptor tyrosine kinase family. Although mutations in either receptor are thought to drive an early oncogenic event through similar pathways, two previous studies reported the mutation-specific gene expression profiles. However, their further conclusions were rather discordant. To clarify the molecular characteristics of differentially expressed genes according to GIST receptor mutations, we combined microarray-based analysis with detailed functional annotations.</p> <p>Methods</p> <p>Total RNA was isolated from 29 frozen gastric GISTs and processed for hybridization on GENECHIP<sup>® </sup>HG-U133 Plus 2.0 microarrays (Affymetrix). <it>KIT </it>and <it>PDGFRA </it>were analyzed by sequencing, while related mRNA levels were analyzed by quantitative RT-PCR.</p> <p>Results</p> <p>Fifteen and eleven tumours possessed mutations in <it>KIT </it>and <it>PDGFRA</it>, respectively; no mutation was found in three tumours. Gene expression analysis identified no discriminative profiles associated with clinical or pathological parameters, even though expression of hundreds of genes differentiated tumour receptor mutation and expression status. Functional features of genes differentially expressed between the two groups of GISTs suggested alterations in angiogenesis and G-protein-related and calcium signalling.</p> <p>Conclusion</p> <p>Our study has identified novel molecular elements likely to be involved in receptor-dependent GIST development and allowed confirmation of previously published results. These elements may be potential therapeutic targets and novel markers of <it>KIT </it>mutation status.</p
Recommended from our members
Discovering the Phylodynamics of RNA Viruses
The advent of extremely high throughput
DNA sequencing ensures that genomic
data from microbial organisms can be
acquired in unprecedented quantities and
with remarkable rapidity. Although this
genomic revolution will affect all microbes
alike, our focus here is on RNA viruses, as
the rapidity of their evolution, which is
observable over the time scale of human
observation, allows phylodynamic inferences
to be made with great precision. In
the foreseeable future it is likely that
complete genome sequencing will become
the standard method of viral characterization,
providing the highest possible resolution
for phylogenetic studies. The rapidity
with which genome sequence data were
generated from the ongoing epidemic of
swine-origin H1N1 influenza A virus [1] is
testament to the power of this technology
- …