448 research outputs found
On the origin of variable structures in the winds of hot luminous stars
Examination of the temporal variability properties of several strong optical
recombination lines in a large sample of Galactic Wolf-Rayet (WR) stars reveals
possible trends, especially in the more homogeneous WC than the diverse WN
subtypes, of increasing wind variability with cooler subtypes. This could imply
that a serious contender for the driver of the variations is stochastic,
magnetic subsurface convection associated with the 170 kK partial-ionization
zone of iron, which should occupy a deeper and larger zone of greater mass in
cooler WR subtypes. This empirical evidence suggests that the heretofore
proposed ubiquitous driver of wind variability, radiative instabilities, may
not be the only mechanism playing a role in the stochastic multiple
small-scaled structures seen in the winds of hot luminous stars. In addition to
small-scale stochastic behaviour, subsurface convection guided by a global
magnetic field with localized emerging loops may also be at the origin of the
large-scale corotating interaction regions as seen frequently in O stars and
occasionally in the winds of their descendant WR stars.Comment: 8 pages, 2 figures and 2 tables. Monthly Notices of the Royal
Astronomical Society 201
La chimiohyperthermie intrapéritonéale (CHIP) dans les cancers ovariens
RĂ©sumĂ©Le cancer de lâovaire reste, en France, la quatriĂšme cause de dĂ©cĂšs par cancer chez la femme. Il sâagit dâune maladie souvent diagnostiquĂ©e Ă un stade Ă©voluĂ© avec carcinose pĂ©ritonĂ©ale (CP) et dont lâhistoire naturelle est marquĂ©e par des rĂ©cidives essentiellement pĂ©ritonĂ©ales et lâacquisition dâun profil de chimiorĂ©sistance. MalgrĂ© les nombreuses lignes de chimiothĂ©rapie systĂ©mique et les chirurgies de cytorĂ©duction (CCR), le pronostic de ces rĂ©cidives reste sombre. Depuis plus de 20ans, plusieurs Ă©quipes spĂ©cialisĂ©es ont dĂ©veloppĂ© un traitement combinĂ© des CP, associant une chirurgie de cytorĂ©duction complĂšte Ă une chimiohyperthermie intrapĂ©ritonĂ©ale (CHIP). Cette thĂ©rapeutique a une large place dans le traitement des CP dâorigine non gynĂ©cologiques. Le rationnel pour une utilisation de la CHIP dans le traitement des CP dâorigine ovarienne est important. Dâune part, 3 Ă©tudes prospectives randomisĂ©es ont dĂ©montrĂ© la supĂ©rioritĂ© de lâutilisation de la chimiothĂ©rapie intrapĂ©ritonĂ©ale (sans hyperthermie) par rapport Ă la chimiothĂ©rapie systĂ©mique sur des patientes sĂ©lectionnĂ©es. Dâautre part, des Ă©tudes rĂ©trospectives et cas-tĂ©moins Ă©valuant la CHIP font Ă©tat de donnĂ©es de survie encourageantes, en particulier en cas de rĂ©cidive chimiorĂ©sistante. NĂ©anmoins, la morbiditĂ© et la mortalitĂ© associĂ©es doivent appeler Ă une sĂ©lection rigoureuse des patientes Ă©ligibles, et Ă une prise en charge multidisciplinaire dans des centres spĂ©cialisĂ©s. LâĂ©valuation de la CHIP doit se faire par le moyen dâĂ©tudes randomisĂ©es Ă diffĂ©rents stades Ă©volutifs : 1re ligne, consolidation, rĂ©cidives quâelles soient chimiorĂ©sistantes ou chimiosensibles. Plusieurs Ă©tudes europĂ©ennes sont en cours.SummaryOvarian cancer remains the fourth leading cause of cancer death in women in France. It is all too often diagnosed at an advanced stage with peritoneal carcinomatosis (PC), but remains confined to the peritoneal cavity throughout much of its natural history. Because of cellular selection pressure over time, most tumor recurrences eventually develop resistance to systemic platinum. Options for salvage therapy include alternative systemic chemotherapies and further cytoreductive surgery (CRS), but the prognosis remains poor. Over the past two decades, a new therapeutic approach to PC has been developed that combines CRS with hyperthermic intraperitoneal chemotherapy (HIPEC). This treatment strategy has already been shown to be effective in non-gynecologic carcinomatosis in numerous reports. There is a strong rationale for the use of HIPEC for PC of ovarian origin. On the one hand, three prospective randomized trials have demonstrated the superiority of intraperitoneal chemotherapy (without hyperthermia) in selected patients compared to systemic chemotherapy. Moreover, retrospective studies and case-control studies of HIPEC have reported encouraging survival data, especially when used to treat chemoresistant recurrence. However, HIPEC has specific morbidity and mortality; this calls for very careful selection of eligible patients by a multidisciplinary team in specialized centers. HIPEC needs to be evaluated by means of randomized trials for ovarian cancer at different developmental stages: as first line therapy, as consolidation, and for chemoresistant recurrence. Several European Phase III studies are currently ongoing
Involvement of Plasmodium falciparum protein kinase CK2 in the chromatin assembly pathway
<p>Abstract</p> <p>Background</p> <p>Protein kinase CK2 is a pleiotropic serine/threonine protein kinase with hundreds of reported substrates, and plays an important role in a number of cellular processes. The cellular functions of <it>Plasmodium falciparum </it>CK2 (PfCK2) are unknown. The parasite's genome encodes one catalytic subunit, PfCK2α, which we have previously shown to be essential for completion of the asexual erythrocytic cycle, and two putative regulatory subunits, PfCK2ÎČ1 and PfCK2ÎČ2.</p> <p>Results</p> <p>We now show that the genes encoding both regulatory PfCK2 subunits (PfCK2ÎČ1 and PfCK2ÎČ2) cannot be disrupted. Using immunofluorescence and electron microscopy, we examined the intra-erythrocytic stages of transgenic parasite lines expressing hemagglutinin (HA)-tagged catalytic and regulatory subunits (HA-CK2α, HA-PfCK2ÎČ1 or HA-PfCK2ÎČ2), and localized all three subunits to both cytoplasmic and nuclear compartments of the parasite. The same transgenic parasite lines were used to purify PfCK2ÎČ1- and PfCK2ÎČ2-containing complexes, which were analyzed by mass spectrometry. The recovered proteins were unevenly distributed between various pathways, with a large proportion of components of the chromatin assembly pathway being present in both PfCK2ÎČ1 and PfCK2ÎČ2 precipitates, implicating PfCK2 in chromatin dynamics. We also found that chromatin-related substrates such as nucleosome assembly proteins (Naps), histones, and two members of the Alba family are phosphorylated by PfCK2α <it>in vitro</it>.</p> <p>Conclusions</p> <p>Our reverse-genetics data show that each of the two regulatory PfCK2 subunits is required for completion of the asexual erythrocytic cycle. Our interactome study points to an implication of PfCK2 in many cellular pathways, with chromatin dynamics being identified as a major process regulated by PfCK2. This study paves the way for a kinome-wide interactomics-based approach to elucidate protein kinase function in malaria parasites.</p
P18-11. DALIA: dendritic cell and lipopeptide-induced immunity against AIDS: a phase I trial
International audiencen.
Metallicity variations in the Type II globular cluster NGC6934
The Hubble Space Telescope photometric survey of Galactic globular clusters
(GCs) has revealed a peculiar "chromosome map" for NGC6934. Besides a typical
sequence, similar to that observed in Type I GCs, NGC 6934 displays additional
stars on the red side, analogous to the anomalous, Type II GCs, as defined in
our previous work. We present a chemical abundance analysis of four red giants
in this GC. Two stars are located on the chromosome map sequence common to all
GCs, and another two on the additional sequence. We find: (i) star-to-star Fe
variations, with the two anomalous stars being enriched by ~0.2 dex. Due to our
small-size sample, this difference is at the ~2.5 sigma level; (ii) no evidence
for variations in the slow neutron-capture abundances over Fe, at odds with
what is often observed in anomalous Type II GCs, e.g. M 22 and Omega Centauri;
(iii) no large variations in light elements C, O and Na, compatible with the
targets location on the lower part of the chromosome map where such variations
are not expected. Since the analyzed stars are homogeneous in light elements,
the only way to reproduce the photometric splits on the sub-giant (SGB) and the
red-giant (RGB) branches is to assume that red-RGB/faint-SGB stars are enhanced
in [Fe/H] by ~0.2. This fact corroborates the spectroscopic evidence of a
metallicity variation in NGC6934. The observed chemical pattern resembles only
partially the other Type II GCs, suggesting that NGC6934 might belong either to
a third class of GCs, or be a link between normal Type I and anomalous Type II
GCs.Comment: 26 pages, 9 figures, accepted for publication in Ap
Cold pressor echocardiography
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24473/1/0000748.pd
Premenopausal endogenous oestrogen levels and breast cancer risk: a meta-analysis.
BACKGROUND: Many of the established risk factors for breast cancer implicate circulating hormone levels in the aetiology of the disease. Increased levels of postmenopausal endogenous oestradiol (E2) have been found to increase the risk of breast cancer, but no such association has been confirmed in premenopausal women. We carried out a meta-analysis to summarise the available evidence in women before the menopause. METHODS: We identified seven prospective studies of premenopausal endogenous E2 and breast cancer risk, including 693 breast cancer cases. From each study we extracted odds ratios of breast cancer between quantiles of endogenous E2, or for unit or s.d. increases in (log transformed) E2, or (where odds ratios were unavailable) summary statistics for the distributions of E2 in breast cancer cases and unaffected controls. Estimates for a doubling of endogenous E2 were obtained from these extracted estimates, and random-effect meta-analysis was used to obtain a pooled estimate across the studies. RESULTS: Overall, we found weak evidence of a positive association between circulating E2 levels and the risk of breast cancer, with a doubling of E2 associated with an odds ratio of 1.10 (95% CI: 0.96, 1.27). CONCLUSION: Our findings are consistent with the hypothesis of a positive association between premenopausal endogenous E2 and breast cancer risk
Infrared photometry and CaT spectroscopy of globular cluster M 28 (NGC 6626)
Recent studies show that the inner Galactic regions host genuine bulge
globular clusters, but also halo intruders, complex remnants of primordial
building blocks, and objects likely accreted during major merging events. In
this study we focus on the properties of M 28, a very old and massive cluster
currently located in the Galactic bulge. We analysed wide-field infrared
photometry collected by the VVV survey, VVV proper motions, and
intermediate-resolution spectra in the calcium triplet range for 113 targets in
the cluster area. Our results in general confirm previous estimates of the
cluster properties available in the literature. We find no evidence of
differences in metallicity between cluster stars, setting an upper limit of
Delta[Fe/H]<0.08 dex to any internal inhomogeneity. We confirm that M 28 is one
of the oldest objects in the Galactic bulge (13-14 Gyr). From this result and
the literature data, we find evidence of a weak age-metallicity relation among
bulge globular clusters that suggests formation and chemical enrichment. In
addition, wide-field density maps show that M 28 is tidally stressed and that
it is losing mass into the general bulge field. Our study indicates that M 28
is a genuine bulge globular cluster, but its very old age and its mass loss
suggest that this cluster could be the remnant of a larger structure, possibly
a primeval bulge building block.Comment: Accepted for publication in Astronomy & Astrophysic
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