Stellar evolution through the ages: period variations in galactic RRab stars as derived from the GEOS database and TAROT telescopes

The theory of stellar evolution can be more closely tested if we have the opportunity to measure new quantities. Nowadays, observations of galactic RR Lyr stars are available on a time baseline exceeding 100 years. Therefore, we can exploit the possibility of investigating period changes, continuing the pioneering work started by V. P. Tsesevich in 1969. We collected the available times of maximum brightness of the galactic RR Lyr stars in the GEOS RR Lyr database. Moreover, we also started new observational projects, including surveys with automated telescopes, to characterise the O-C diagrams better. The database we built has proved to be a very powerful tool for tracing the period variations through the ages. We analyzed 123 stars showing a clear O-C pattern (constant, parabolic or erratic) by means of different least-squares methods. Clear evidence of period increases or decreases at constant rates has been found, suggesting evolutionary effects. The median values are beta=+0.14 day/Myr for the 27 stars showing a period increase and beta=-0.20 day/Myr for the 21 stars showing a period decrease. The large number of RR Lyr stars showing a period decrease (i.e., blueward evolution) is a new and intriguing result. There is an excess of RR Lyr stars showing large, positive $\beta$ values. Moreover, the observed beta values are slightly larger than those predicted by theoretical models.Comment: 15 pages, 9 figures; to be published in Astronomy and Astrophysics; full resolution version available at http://dbrr.ast.obs-mip.fr/tarot/publis/publis.htm

Lower leukotriene C4 levels in bronchoalveolar lavage fluid of asthmatic subjects after 2.5 years of inhaled corticosteroid therapy

Long-term treatment with inhaled corticosteroids has been shown to result in improvement of symptoms and lung function in subjects with asthma. Arachidonic acid (AA) metabolites are thought to play a role in the pathophysiology of asthma. It was assessed whether differences could be found in bronchoalveolar lavage (BAL) AA metabolite levels between subjects with asthma who were treated for 2.5 years with inhaled bronchodilators alone or in combination with inhaled corticosteroids. Prostaglandin (PG)D2, PGF2α, 6-keto-PGF1α, thromboxane B2, leukotriene (LT)C4 and LTB4 levels and cell numbers were assessed in BAL fluid from 22 non-smoking asthmatic subjects. They were participating in a randomized, double-blind multicentre drug trial over a period of 2.5 years. Results of the group treated with inhaled corticosteroids (CS+: beclomethasone 200 μg four times daily) were compared with the other group (CS−) which was treated with either ipratropium bromide (40 μg four times daily) or placebo. BAL LTC4 levels of asthmatic subjects were significantly lower after 2.5 years inhaled corticosteroid therapy (CS+, 9(1–17) pg/ml vs. CS−, 16(6-53) pg/ml; p = 0.01). The same trend was observed for the PGD2 levels. The results suggest that inhaled corticosteroids may exert their beneficial effect on lung function via a mechanism in which inhibition of LTC4 synthesis in the airways is involved

Can AMP induce sputum eosinophils, even in subjects with complete asthma remission?

<p>Abstract</p> <p>Background</p> <p>The definition of <b>"</b>clinical asthma remission" is based on absence of symptoms and use of medication. However, in the majority of these subjects airway inflammation is still present when measured. In the present study we investigated whether "complete asthma remission", additionally defined by the absence of bronchial hyperresponsiveness (BHR) and the presence of a normal lung function, is associated with the absence of airway inflammation.</p> <p>Methods</p> <p>Patients with a former diagnosis of asthma and a positive histamine provocation test were re-examined to identify subjects with complete asthma remission (no asthma symptoms or medication, PC₂₀histamine > 32 mg/ml, FEV₁> 90% predicted). Patients with PC₂₀histamine ≤ 32 mg/ml were defined as current asthmatics and were divided in two groups, i.e. asthmatics with and without BHR to adenosine 5'monophoshate (AMP). Sputum induction was performed 1 week before and 1 hour after AMP provocation. Sputum induction and AMP provocation were previously shown to be sensitive markers of airway inflammation.</p> <p>Results</p> <p>Seven patients met criteria for complete asthma remission. Twenty-three were current asthmatics, including twelve without hyperresponsiveness to AMP. Subjects with complete asthma remission showed no AMP-induced sputum eosinophilia (median (range) 0.2 (0 - 4.6)% at baseline and 0.2 (0 - 2.6)% after AMP). After AMP, current asthmatics had a significant increase in sputum eosinophils (0.5 (0 - 26.0)% at baseline and 2.6 (0 - 32.0) % after AMP), as had the subgroup of current asthmatics without hyperresponsiveness to AMP (0.2 (0 - 1.8)% at baseline and 1.3 (0 - 6.3)% after AMP).</p> <p>Conclusions</p> <p>Subjects with complete asthma remission, in contrast to subjects with current asthma, do not respond with eosinophilic inflammation in sputum after AMP provocations. These data lend support to the usefulness of the definition of complete asthma remission.</p

Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy

We review HB stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters (GCs) in the HB morphology-metallicity plane both exclude, with high statistical significance, the possibility that the Galactic halo may have formed from the accretion of dwarf galaxies resembling present-day Milky Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the second-parameter problem is presented. A technique is proposed to estimate the HB types of extragalactic GCs on the basis of integrated far-UV photometry. The relationship between the absolute V magnitude of the HB at the RR Lyrae level and metallicity, as obtained on the basis of trigonometric parallax measurements for the star RR Lyrae, is also revisited, giving a distance modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are studied. Finally, the conductive opacities used in evolutionary calculations of low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and Space Scienc

Alterations in Adenosine Metabolism and Signaling in Patients with Chronic Obstructive Pulmonary Disease and Idiopathic Pulmonary Fibrosis

Background: Adenosine is generated in response to cellular stress and damage and is elevated in the lungs of patients with chronic lung disease. Adenosine signaling through its cell surface receptors serves as an amplifier of chronic lung disorders, suggesting adenosine-based therapeutics may be beneficial in the treatment of lung diseases such as chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). Previous studies in mouse models of chronic lung disease demonstrate that the key components of adenosine metabolism and signaling are altered. Changes include an upregulation of CD73, the major enzyme of adenosine production and down-regulation of adenosine deaminase (ADA), the major enzyme for adenosine metabolism. In addition, adenosine receptors are elevated. Methodology/Principal Findings: The focus of this study was to utilize tissues from patients with COPD or IPF to examine whether changes in purinergic metabolism and signaling occur in human disease. Results demonstrate that the levels of CD73 and A2BR are elevated in surgical lung biopsies from severe COPD and IPF patients. Immunolocalization assays revealed abundant expression of CD73 and the A2BR in alternatively activated macrophages in both COPD and IPF samples. In addition, mediators that are regulated by the A 2BR, such as IL-6, IL-8 and osteopontin were elevated in these samples and activation of the A 2BR on cells isolated from the airways of COPD and IPF patients was shown to directly induce the production of these mediators. Conclusions/Significance: These findings suggest that components of adenosine metabolism and signaling are altered in

Variable Stars in Galactic Globular Clusters

Based on a search of the literature up to May 2001, the number of known variable stars in Galactic globular clusters is approximately 3000. Of these, more than 2200 have known periods and the majority (approximately 1800) are of the RR Lyrae type. In addition to the RR Lyrae population, there are approximately 100 eclipsing binaries, 120 SX Phe variables, 60 Cepheids (including population II Cepheids, anomalous Cepheids and RV Tauri) and 120 SR/red variables. The mean period of the fundamental mode RR Lyrae variables is 0.585, for the overtone variables it is 0.342 (0.349 for the first-overtone pulsators and 0.296 for the second-overtone pulsators) and approximately 30% are overtone pulsators. These numbers indicate that about 65% of RR Lyrae variables in Galactic globular clusters belong to Oosterhoff type I systems. The mean period of the RR Lyrae variables in the Oosterhoff type I clusters seems to be correlated with metal abundance in the sense that the periods are longer in the more metal poor clusters. Such a correlation does not exist for the Oosterhoff type II clusters. Most of the Cepheids are in clusters with blue horizontal branches.Comment: 45 pages, 10 figures, to be published in AJ November 200

P1 receptors and cytokine secretion

Evidence has accumulated in the last three decades to suggest tissue protection and regeneration by adenosine in multiple different cell types. Adenosine produced in hypoxic or inflamed environments reduces tissue injury and promotes repair by receptor-mediated mechanisms. Among other actions, regulation of cytokine production and secretion by immune cells, astrocytes and microglia (the brain immunocytes) has emerged as a main mechanism at the basis of adenosine effects in diseases characterized by a marked inflammatory component. Many recent studies have highlighted that signalling through A1 and A2A adenosine receptors can powerfully prevent the release of pro-inflammatory cytokines, thus inhibiting inflammation and reperfusion injury. However, the activation of adenosine receptors is not invariably protective of tissues, as signalling through the A2B adenosine receptor has been linked to pro-inflammatory actions which are, at least in part, mediated by increased release of pro-inflammatory cytokines from epithelial cells, astrocytes and fibroblasts. Here, we discuss the multiple actions of P1 receptors on cytokine secretion, by analyzing, in particular, the role of the various adenosine receptor subtypes, the complex reciprocal interplay between the adenosine and the cytokine systems, their pathophysiological significance and the potential of adenosine receptor ligands as new anti-inflammatory agents

Photometric multi-site campaign on the open cluster NGC 884 I. Detection of the variable stars

CONTEXT: Recent progress in the seismic interpretation of field beta Cep stars has resulted in improvements of the physics in the stellar structure and evolution models of massive stars. Further asteroseismic constraints can be obtained from studying ensembles of stars in a young open cluster, which all have similar age, distance and chemical composition. AIMS: To improve our comprehension of the beta Cep stars, we studied the young open cluster NGC 884 to discover new B-type pulsators, besides the two known beta Cep stars, and other variable stars. METHODS: An extensive multi-site campaign was set up to gather accurate CCD photometry time series in four filters (U, B, V, I) of a field of NGC884. Fifteen different instruments collected almost 77500 CCD images in 1286 hours. The images were calibrated and reduced to transform the CCD frames into interpretable differential light curves. Various variability indicators and frequency analyses were applied to detect variable stars in the field. Absolute photometry was taken to deduce some general cluster and stellar properties. RESULTS: We achieved an accuracy for the brightest stars of 5.7 mmag in V, 6.9 mmag in B, 5.0 mmag in I and 5.3 mmag in U. The noise level in the amplitude spectra is 50 micromag in the V band. Our campaign confirms the previously known pulsators, and we report more than one hundred new multi- and mono-periodic B-, A- and F-type stars. Their interpretation in terms of classical instability domains is not straightforward, pointing to imperfections in theoretical instability computations. In addition, we have discovered six new eclipsing binaries and four candidates as well as other irregular variable stars in the observed field.Comment: Accepted for publication in Astronomy and Astrophysics, 21 pages, 14 figures, 4 tables. The full appendix is available at http://www.ster.kuleuven.be/~sophies/Appendix.pdf (74 MB, 169 pages, 343 figures, 1 table

LNCaP Atlas: Gene expression associated with in vivo progression to castration-recurrent prostate cancer

<p>Abstract</p> <p>Background</p> <p>There is no cure for castration-recurrent prostate cancer (CRPC) and the mechanisms underlying this stage of the disease are unknown.</p> <p>Methods</p> <p>We analyzed the transcriptome of human LNCaP prostate cancer cells as they progress to CRPC <it>in vivo </it>using replicate LongSAGE libraries. We refer to these libraries as the LNCaP atlas and compared these gene expression profiles with current suggested models of CRPC.</p> <p>Results</p> <p>Three million tags were sequenced using <it>in vivo </it>samples at various stages of hormonal progression to reveal 96 novel genes differentially expressed in CRPC. Thirty-one genes encode proteins that are either secreted or are located at the plasma membrane, 21 genes changed levels of expression in response to androgen, and 8 genes have enriched expression in the prostate. Expression of 26, 6, 12, and 15 genes have previously been linked to prostate cancer, Gleason grade, progression, and metastasis, respectively. Expression profiles of genes in CRPC support a role for the transcriptional activity of the androgen receptor (<it>CCNH, CUEDC2, FLNA, PSMA7</it>), steroid synthesis and metabolism (<it>DHCR24, DHRS7</it>, <it>ELOVL5, HSD17B4</it>, <it>OPRK1</it>), neuroendocrine (<it>ENO2, MAOA, OPRK1, S100A10, TRPM8</it>), and proliferation (<it>GAS5</it>, <it>GNB2L1</it>, <it>MT-ND3</it>, <it>NKX3-1</it>, <it>PCGEM1</it>, <it>PTGFR</it>, <it>STEAP1</it>, <it>TMEM30A</it>), but neither supported nor discounted a role for cell survival genes.</p> <p>Conclusions</p> <p>The <it>in vivo </it>gene expression atlas for LNCaP was sequenced and support a role for the androgen receptor in CRPC.</p