856 research outputs found
Neutralizing antibodies in cats infected with feline immunodeficiency virus.
Sera from cats experimentally infected with five isolates of feline immunodeficiency virus (FIV) from various geographical regions and from FIV enzyme-linked immunosorbent assay-seropositive field cats from four European countries neutralized the Petaluma strain of FIV (FIV-P), originally isolated in California, at high titers. In addition, FIV-P and a European isolate proved equally susceptible to neutralization by all sera tested. Coupled with observations by Fevereiro et al. (M. Fevereiro, C. Roneker, A. Laufs, L. Tavares, and F. de Noronha, J. Gen. Virol. 72:617-622, 1991), these findings indicate that most if not all FIV strains circulating in Europe and the United States share important neutralization-inducing epitopes
The scaling relations of early--type galaxies in clusters I. Surface photometry in seven nearby clusters
This is the first paper of a series investigating the scaling relations of
early-type galaxies in clusters. Here we illustrate the multi-band imagery and
the image reduction and calibration procedures relative to the whole sample of
22 clusters at 0.05 < z < 0.25. We also present the detailed surface photometry
of 312 early-type galaxies in 7 clusters in the first redshift bin,
z~0.025-0.075. We give for each galaxy the complete set of luminosity and
geometrical profiles, and and a number of global, photometric and morphological
parameters. They have been evaluated taking into account the effects of seeing.
Internal consistency checks and comparisons with data in the literature confirm
the quality of our analysis. These data, together with the spectroscopic ones
presented in the second paper of the series, will provide the local calibration
of the scaling relations.Comment: 36 pages, 13 figures, 7 tables, accepted for publication in A&
Modulation of the virus-receptor interaction by mutations in the V5 loop of feline immunodeficiency virus (FIV) following in vivo escape from neutralising antibody
<b>BACKGROUND:</b> In the acute phase of infection with feline immunodeficiency virus (FIV), the virus targets activated CD4+ T cells by utilising CD134 (OX40) as a primary attachment receptor and CXCR4 as a co-receptor. The nature of the virus-receptor interaction varies between isolates; strains such as GL8 and CPGammer recognise a "complex" determinant on CD134 formed by cysteine-rich domains (CRDs) 1 and 2 of the molecule while strains such as PPR and B2542 require a more "simple" determinant comprising CRD1 only for infection. These differences in receptor recognition manifest as variations in sensitivity to receptor antagonists. In this study, we ask whether the nature of the virus-receptor interaction evolves in vivo.<p></p>
<b>RESULTS:</b> Following infection with a homogeneous viral population derived from a pathogenic molecular clone, a quasispecies emerged comprising variants with distinct sensitivities to neutralising antibody and displaying evidence of conversion from a "complex" to a "simple" interaction with CD134. Escape from neutralising antibody was mediated primarily by length and sequence polymorphisms in the V5 region of Env, and these alterations in V5 modulated the virus-receptor interaction as indicated by altered sensitivities to antagonism by both anti-CD134 antibody and soluble CD134.<p></p>
<b>CONCLUSIONS:</b> The FIV-receptor interaction evolves under the selective pressure of the host humoral immune response, and the V5 loop contributes to the virus-receptor interaction. Our data are consistent with a model whereby viruses with distinct biological properties are present in early versus late infection and with a shift from a "complex" to a "simple" interaction with CD134 with time post-infection.<p></p>
Physical Parameters of Some Close Binaries: ET Boo, V1123 Tau, V1191 Cyg, V1073 Cyg and V357 Peg
With the aim of providing new and up-to-date absolute parameters of some
close binary systems, new BVR CCD photometry was carried out at the Ankara
University Observatory (AUG) for five eclipsing binaries, ET Boo, V1123 Tau,
V1191 Cyg, V1073 Cyg and V357 Peg between April, 2007 and October, 2008. In
this paper, we present the orbital solutions for these systems obtained by
simultaneous light and radial velocity curve analyses. Extensive orbital
solution and absolute parameters for ET Boo system were given for the first
time through this study. According to the analyses, ET Boo is a detached binary
while the parameters of four remaining systems are consistent with the nature
of contact binaries. The evolutionary status of the components of these systems
are also discussed by referring to their absolute parameters found in this
study.Comment: this accepted paper will be published in New Astronom
Selective expansion of viral variants following experimental transmission of a reconstituted feline immunodeficiency virus quasispecies
Following long-term infection with virus derived from the pathogenic GL8 molecular clone of feline immunodeficiency virus (FIV), a range of viral variants emerged with distinct modes of interaction with the viral receptors CD134 and CXCR4, and sensitivities to neutralizing antibodies. In order to assess whether this viral diversity would be maintained following subsequent transmission, a synthetic quasispecies was reconstituted comprising molecular clones bearing envs from six viral variants and its replicative capacity compared in vivo with a clonal preparation of the parent virus. Infection with either clonal (Group 1) or diverse (Group 2) challenge viruses, resulted in a reduction in CD4+ lymphocytes and an increase in CD8+ lymphocytes. Proviral loads were similar in both study groups, peaking by 10 weeks post-infection, a higher plateau (set-point) being achieved and maintained in study Group 1. Marked differences in the ability of individual viral variants to replicate were noted in Group 2; those most similar to GL8 achieved higher viral loads while variants such as the chimaeras bearing the B14 and B28 Envs grew less well. The defective replication of these variants was not due to suppression by the humoral immune response as virus neutralising antibodies were not elicited within the study period. Similarly, although potent cellular immune responses were detected against determinants in Env, no qualitative differences were revealed between animals infected with either the clonal or the diverse inocula. However, in vitro studies indicated that the reduced replicative capacity of variants B14 and B28 in vivo was associated with altered interactions between the viruses and the viral receptor and co-receptor. The data suggest that viral variants with GL8-like characteristics have an early, replicative advantage and should provide the focus for future vaccine development
HGF Mediates the Anti-inflammatory Effects of PRP on Injured Tendons
Platelet-rich plasma (PRP) containing hepatocyte growth factor (HGF) and other growth factors are widely used in orthopaedic/sports medicine to repair injured tendons. While PRP treatment is reported to decrease pain in patients with tendon injury, the mechanism of this effect is not clear. Tendon pain is often associated with tendon inflammation, and HGF is known to protect tissues from inflammatory damages. Therefore, we hypothesized that HGF in PRP causes the anti-inflammatory effects. To test this hypothesis, we performed in vitro experiments on rabbit tendon cells and in vivo experiments on a mouse Achilles tendon injury model. We found that addition of PRP or HGF decreased gene expression of COX-1, COX-2, and mPGES-1, induced by the treatment of tendon cells in vitro with IL-1β. Further, the treatment of tendon cell cultures with HGF antibodies reduced the suppressive effects of PRP or HGF on IL-1β-induced COX-1, COX-2, and mPGES-1 gene expressions. Treatment with PRP or HGF almost completely blocked the cellular production of PGE2 and the expression of COX proteins. Finally, injection of PRP or HGF into wounded mouse Achilles tendons in vivo decreased PGE2 production in the tendinous tissues. Injection of platelet-poor plasma (PPP) however, did not reduce PGE2 levels in the wounded tendons, but the injection of HGF antibody inhibited the effects of PRP and HGF. Further, injection of PRP or HGF also decreased COX-1 and COX-2 proteins. These results indicate that PRP exerts anti-inflammatory effects on injured tendons through HGF. This study provides basic scientific evidence to support the use of PRP to treat injured tendons because PRP can reduce inflammation and thereby reduce the associated pain caused by high levels of PGE2. © 2013 Zhang et al
Epsilon Indi Ba, Bb: a detailed study of the nearest known brown dwarfs
The discovery of epsilon Indi Ba, Bb, a binary brown dwarf system very close
to the Sun, makes possible a concerted campaign to characterise the physical
parameters of two T dwarfs. Recent observations suggest substellar atmospheric
and evolutionary models may be inconsistent with observations, but there have
been few conclusive tests to date. We therefore aim to characterise these
benchmark brown dwarfs to place constraints on such models. We have obtained
high angular resolution optical, near-infrared, and thermal-infrared imaging
and medium-resolution (up to R~5000) spectroscopy of epsilon Indi Ba, Bb with
the ESO VLT and present VRIzJHKL'M' broad-band photometry and 0.63--5.1 micron
spectroscopy of the individual components. Furthermore, we use deep AO-imaging
to place upper limits on the (model-dependent) mass of any further system
members. We derive luminosities of log L/L_sun = -4.699+/-0.017 and
-5.232+/-0.020 for epsilon Indi Ba, Bb, respectively, and using the dynamical
system mass and COND03 evolutionary models predict a system age of 3.7--4.3
Gyr, in excess of previous estimates and recent predictions from observations
of these brown dwarfs. Moreover, the effective temperatures of 1352--1385 K and
976--1011 K predicted from the COND03 evolutionary models, for epsilon Indi Ba
and Bb respectively, are in disagreement with those derived from the comparison
of our data with the BT-Settl atmospheric models where we find effective
temperatures of 1300--1340 K and 880--940 K, for epsilon Indi Ba and Bb
respectively, with surface gravities of log g=5.25 and 5.50. Finally, we show
that spectroscopically determined effective temperatures and surface gravities
for ultra-cool dwarfs can lead to underestimated masses even where precise
luminosity constraints are available.Comment: 27 pages, 30 figures, 9 tables, accepted for publication in Astronomy
and Astrophysic
Airline delays, congestion internalization and non-price spillover effects of low cost carrier entry
This paper develops an econometric model of flight delays to investigate the
influence of competition and dominance on the incentives of carriers to
maintain on-time performance. We consider both the route and the airport levels
to inspect the local and global effects of competition, with a unifying
framework to test the hypotheses of 1. airport congestion internalization and
2. the market competition-quality relationship in a single econometric model.
In particular, we examine the impacts of the entry of low cost carriers (LCC)
on the flight delays of incumbent full service carriers in the Brazilian
airline industry. The main results indicate a highly significant effect of
airport congestion self-internalization in parallel with route-level quality
competition. Additionally, the potential competition caused by LCC presence
provokes a global effect that suggests the existence of non-price spillovers of
the LCC entry to non-entered routes
Seatbelt: A Double-Edged Sword
Intra-abdominal vascular injury due to blunt trauma is unusual in children. Due to its rarity, detailed reports dealing with its management are scarce in paediatric literature. Diagnosis of these injuries is challenging, and a high degree of awareness is necessary for rapid identification and treatment of these injuries. We report the case of a child with seatbelt sign and mesenteric vein injury due to blunt trauma to the abdomen during a motor vehicle accident where the seatbelt was incorrectly placed. She also sustained cervical vertebral injury. The pattern of injuries in children in these situations may differ from that found in adults. While seatbelts have undoubtedly saved many lives, awareness about correct placement of these restraints is extremely necessary
Mediterranean diet and type 2 diabetes risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) study: the InterAct project.
OBJECTIVE: To study the association between adherence to the Mediterranean dietary pattern (MDP) and risk of developing type 2 diabetes, across European countries. RESEARCH DESIGN AND METHODS: We established a case-cohort study including 11,994 incident type 2 diabetic case subjects and a stratified subcohort of 15,798 participants selected from a total cohort of 340,234 participants with 3.99 million person-years of follow-up, from eight European cohorts participating in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. The relative Mediterranean diet score (rMED) (score range 0-18) was used to assess adherence to MDP on the basis of reported consumption of nine dietary components characteristic of the Mediterranean diet. Cox proportional hazards regression, modified for the case-cohort design, was used to estimate the association between rMED and risk of type 2 diabetes, adjusting for confounders. RESULTS: The multiple adjusted hazard ratios of type 2 diabetes among individuals with medium (rMED 7-10 points) and high adherence to MDP (rMED 11-18 points) were 0.93 (95% CI 0.86-1.01) and 0.88 (0.79-0.97), respectively, compared with individuals with low adherence to MDP (0-6 points) (P for trend 0.013). The association between rMED and type 2 diabetes was attenuated in people <50 years of age, in obese participants, and when the alcohol, meat, and olive oil components were excluded from the score. CONCLUSIONS: In this large prospective study, adherence to the MDP, as defined by rMED, was associated with a small reduction in the risk of developing type 2 diabetes in this European population
- …
