A line confusion-limited millimeter survey of Orion KL. III. Sulfur oxide species

We present a study of the sulfur-bearing species detected in a line confusion-limited survey towards Orion KL performed with the IRAM 30m telescope in the range 80-281 GHz. The study is part of an analysis of the line survey divided into families of molecules. Our aim is to derive accurate physical conditions and molecular abundances in the different components of Orion KL from observed SO and SO2 lines. First we assumed LTE conditions obtain rotational temperatures. We then used a radiative transfer model, assuming either LVG or LTE excitation to derive column densities of these molecules in the different components of Orion KL. We have detected 68 lines of SO, 34SO, 33SO, and S18O and 653 lines of SO2, 34SO2, 33SO2, SO18O and SO2 v2=1. We provide column densities for all of them and also upper limits for the column densities of S17O, 36SO, 34S18O, SO17O and 34SO2 v2=1 and for several undetected sulfur-bearing species. In addition, we present 2'x2' maps around Orion IRc2 of SO2 transitions with energies from 19 to 131 K and also maps with four transitions of SO, 34SO and 34SO2. We observe an elongation of the gas along the NE-SW direction. An unexpected emission peak appears at 20.5 km/s in most lines of SO and SO2. A study of the spatial distribution of this emission feature shows that it is a new component ~5" in diameter, which lies ~4" west of IRc2. We suggest the emission from this feature is related to shocks associated to the BN object. The highest column densities for SO and SO2 are found in the high-velocity plateau (a region dominated by shocks) and in the hot core. These values are up to three orders of magnitude higher than the results for the ridge components. We also find high column densities for their isotopologues in both components. Therefore, we conclude that SO and SO2 are good tracers, not only of regions affected by shocks, but also of regions with warm dense gas.Comment: Paper (ref AA/2013/21285) accepted for publication by A&A. 52 Pages, 26 figures, 13 table

Extended warm gas in Orion KL as probed by methyl cyanide

In order to study the temperature distribution of the extended gas within the Orion Kleinmann-Low nebula, we have mapped the emission by methyl cyanide (CH3CN) in its J=6_K-5_K, J=12_K-11_K, J=13_K-12_K, and J=14_K-13_K transitions at an average angular resolution of ~10 arcsec (22 arcsec for the 6_K-5_K lines), as part of a new 2D line survey of this region using the IRAM 30m telescope. These fully sampled maps show extended emission from warm gas to the northeast of IRc2 and the distinct kinematic signatures of the hot core and compact ridge source components. We have constructed population diagrams for the four sets of K-ladder emission lines at each position in the maps and have derived rotational excitation temperatures and total beam-averaged column densities from the fitted slopes. In addition, we have fitted LVG model spectra to the observations to determine best-fit physical parameters at each map position, yielding the distribution of kinetic temperatures across the region. The resulting temperature maps reveal a region of hot (T > 350 K) material surrounding the northeastern edge of the hot core, whereas the column density distribution is more uniform and peaks near the position of IRc2. We attribute this region of hot gas to shock heating caused by the impact of outflowing material from active star formation in the region, as indicated by the presence of broad CH3CN lines. This scenario is consistent with predictions from C-shock chemical models that suggest that gas-phase methyl cyanide survives in the post-shock gas and can be somewhat enhanced due to sputtering of grain mantles in the passing shock front.Comment: 24 pages, 20 figures, accepted for publication in A&

A combined IRAM and Herschel/HIFI study of cyano(di)acetylene in Orion KL: tentative detection of DC3N

We present a study of cyanoacetylene (HC3N) and cyanodiacetylene (HC5N) in Orion KL, through observations from two line surveys performed with the IRAM 30m telescope and the HIFI instrument on board the Herschel telescope. The frequency ranges covered are 80-280 GHz and 480-1906 GHz. We model the observed lines of HC3N, HC5N, their isotopologues (including DC3N), and vibrational modes, using a non-LTE radiative transfer code. To investigate the chemical origin of HC3N and DC3N in Orion KL, we use a time-dependent chemical model. We detect 40 lines of the ground state of HC3N and 68 lines of its 13C isotopologues. We also detect 297 lines of six vibrational modes of this molecule (nu_7, 2nu_7, 3nu_7, nu_6, nu_5, and nu_6+nu_7) and 35 rotational lines of the ground state of HC5N. We report the first tentative detection of DC3N in a giant molecular cloud with a DC3N/HC3N abundance ratio of 0.015. We provide column densities and isotopic and molecular abundances. We also perform a 2x2" map around Orion IRc2 and we present maps of HC3N lines and maps of lines of the HC3N vibrational modes nu_6 and nu_7. In addition, a comparison of our results for HC3N with those in other clouds allows us to derive correlations between the column density, the FWHM, the mass, and the luminosity of the clouds. The high column densities of HC3N obtained in the hot core, make this molecule an excellent tracer of hot and dense gas. In addition, the large frequency range covered reveals the need to consider a temperature and density gradient in the hot core in order to obtain better line fits. The high D/H ratio (comparable to that obtained in cold clouds) that we derive suggests a deuterium enrichment. Our chemical models indicate that the possible deuterated HC3N present in Orion KL is formed during the gas-phase. This fact provides new hints concerning the processes leading to deuteration.Comment: 50 pages, 33 figures, 13 tables. Accepted for publication in A&

Involvement of nitric oxide in the mitochondrial action of efavirenz: a differential effect on neurons and glial cells

The anti-human immunodeficiency virus (HIV) drug efavirenz (EFV) alters mitochondrial function in cultured neurons and glial cells. Nitric oxide (NO) is a mediator of mitochondrial dysfunction associated with HIV central nervous system symptoms. We show that EFV promotes inducible nitric oxide synthase (iNOS) expression in cultured glial cells and generated NO undermines their mitochondrial function, as inhibition of NOS partially reverses this effect. EFV inhibits mitochondrial Complex I in both neurons and glia; however, when the latter cells are treated for longer periods, other mitochondrial complexes are also affected in accordance with the increased NO production. These findings shed light on the mechanisms responsible for the frequent EFV-associated neurotoxicity

Neuronal Bioenergetics and Acute Mitochondrial Dysfunction: A Clue to Understanding the Central Nervous System Side Effects of Efavirenz

Background. Neurological pathogenesis is associated with mitochondrial dysfunction and differences in neuronal/glial handling of oxygen and glucose. The main side effects attributed to efavirenz involve the CNS, but the underlying mechanisms are unclear. Methods. Human cell lines and rat primary cultures of neurons and astrocytes were treated with clinically relevant efavirenz concentration. Results. Efavirenz alters mitochondrial respiration, enhances reactive oxygen species generation, undermines mitochondrial membrane potential, and reduces adenosine triphosphate (ATP) levels in a concentration-dependent fashion in both neurons and glial cells. However, it activates adenosine monophosphate–activated protein kinase only in glial cells, upregulating glycolysis and increasing intracellular ATP levels, which do not occur in neurons. To reproduce the conditions that often exist in human immunodeficiency virus–related neuroinflammatory disorders, the effects of efavirenz were evaluated in the presence of exogenous nitric oxide, an inflammatory mediator and mitochondrial inhibitor. The combination potentiated the effects on mitochondrial parameters in both neurons and glial cells, but ATP generation and lactate production were enhanced only in glial cells. Conclusions. Efavirenz affects the bioenergetics of neurons through a mechanism involving acute mitochondrial inhibition, an action exacerbated in neuroinflammatory conditions. A similar scenario of glial cells survival and degeneration of neurons with signs of mitochondrial dysfunction and oxidative stress has been associated with neurocognitive disorders

Enhanced Antitumor Immunity in Mice Deficient in CD69

We investigated the in vivo role of CD69 by analyzing the susceptibility of CD69−/− mice to tumors. CD69−/− mice challenged with MHC class I− tumors (RMA-S and RM-1) showed greatly reduced tumor growth and prolonged survival compared with wild-type (WT) mice. The enhanced anti–tumor response was NK cell and T lymphocyte–mediated, and was due, at least in part, to an increase in local lymphocytes. Resistance of CD69−/− mice to MHC class I− tumor growth was also associated with increased production of the chemokine MCP-1, diminished TGF-β production, and decreased lymphocyte apoptosis. Moreover, the in vivo blockade of TGF-β in WT mice resulted in enhanced anti–tumor response. In addition, CD69 engagement induced NK and T cell production of TGF-β, directly linking CD69 signaling to TGF-β regulation. Furthermore, anti-CD69 antibody treatment in WT mice induced a specific down-regulation in CD69 expression that resulted in augmented anti–tumor response. These data unmask a novel role for CD69 as a negative regulator of anti–tumor responses and show the possibility of a novel approach for the therapy of tumors

Evolution of Chemistry in the envelope of Hot Corinos (ECHOS). I. Extremely young sulphur chemistry in the isolated Class 0 object B335

Within the project Evolution of Chemistry in the envelope of HOt corinoS (ECHOS), we present a study of sulphur chemistry in the envelope of the Class 0 source B335 through observations in the spectral range 7, 3, and 2 mm. We have modelled observations assuming LTE and LVG approximation. We have also used the code Nautilus to study the time evolution of sulphur species. We have detected 20 sulphur species with a total gas-phase S abundance similar to that found in the envelopes of other Class 0 objects, but with significant differences in the abundances between sulphur carbon chains and sulphur molecules containing oxygen and nitrogen. Our results highlight the nature of B335 as a source especially rich in sulphur carbon chains unlike other Class 0 sources. The low presence or absence of some molecules, such as SO and SO+, suggests a chemistry not particularly influenced by shocks. We, however, detect a large presence of HCS+ that, together with the low rotational temperatures obtained for all the S species (<15 K), reveals the moderate or low density of the envelope of B335. We also find that observations are better reproduced by models with a sulphur depletion factor of 10 with respect to the sulphur cosmic elemental abundance. The comparison between our model and observational results for B335 reveals an age of 10$^4$$<$t$<$10$^5$ yr, which highlights the particularly early evolutionary stage of this source. B335 presents a different chemistry compared to other young protostars that have formed in dense molecular clouds, which could be the result of accretion of surrounding material from the diffuse cloud onto the protostellar envelope of B335. In addition, the analysis of the SO2/C2S, SO/CS, and HCS+/CS ratios within a sample of prestellar cores and Class 0 objects show that they could be used as good chemical evolutionary indicators of the prestellar to protostellar transition

Gas phase Elemental abundances in Molecular cloudS (GEMS) VI. A sulphur journey across star-forming regions: study of thioformaldehyde emission

In the context of the IRAM 30m Large Program GEMS, we present a study of thioformaldehyde in several starless cores located in star-forming filaments of Taurus, Perseus, and Orion. We investigate the influence of the environmental conditions on the abundances of these molecules in the cores, and the effect of time evolution. We have modelled the observed lines of H2CS, HDCS, and D2CS using the radiative transfer code RADEX. We have also used the chemical code Nautilus to model the evolution of these species depending on the characteristics of the starless cores. We derive column densities and abundances for all the cores. We also derive deuterium fractionation ratios, Dfrac, to determine and compare the evolutionary stage between different parts of each star-forming region. Our results indicate that the north region of the B213 filament in Taurus is more evolved than the south, while the north-eastern part of Perseus presents an earlier evolutionary stage than the south-western zone. Model results also show that Dfrac decreases with the cosmic-ray ionisation rate, while it increases with density and with the degree of sulphur depletion. In particular, we only reproduce the observations when the initial sulphur abundance in the starless cores is at least one order of magnitude lower than the solar elemental sulphur abundance. The progressive increase in HDCS/H2CS and D2CS/H2CS with time makes these ratios powerful tools for deriving the chemical evolutionary stage of starless cores. However, they cannot be used to derive the temperature of these regions, since both ratios present a similar evolution at two different temperature ranges (7-11 K and 15-19 K). Regarding chemistry, (deuterated) thioformaldehyde is mainly formed through gas-phase reactions (double-replacement and neutral-neutral displacement reactions), while surface chemistry plays an important role as a destruction mechanism.Comment: 31 pages, 26 figure

Prenatal exposure to NO2 and ultrasound measures of fetal growth in the Spanish INMA cohort

__Background:__ Air pollution exposure during pregnancy has been associated with impaired fetal growth. However, few studies have measured fetal biometry longitudinally, remaining unclear as to whether there are windows of special vulnerability. __Objective:__ The aim was to investigate the impact of nitrogen dioxide (NO2) exposure on fetal and neonatal biometry in the Spanish INMA study. Methods: Biparietal diameter (BPD), femur length (FL), abdominal circumference (AC), and estimated fetal weight (EFW) were evaluated for up to 2,478 fetuses in each trimester of pregnancy. Size at 12, 20, and 34 weeks of gestation and growth between these points, as well as anthropometry at birth, were assessed by SD scores derived using cohort-specific growth curves. Temporally adjusted land-use regression was used to estimate exposure to NO2 at home addresses for up to 2,415 fetuses. Associations were investigated by linear regression in each cohort and subsequent meta-analysis. __Results:__ A 10-μg/m3 increase in average exposure to NO2 during weeks 0-12 was associated with reduced growth at weeks 0-12 in AC (-2.1%; 95% CI: -3.7, -0.6) and EFW (-1.6%; 95% CI: -3.0, -0.3). The same exposure was inversely associated with reduced growth at weeks 20-34 in BPD (-2.6%; 95% CI: -3.9, -1.2), AC (-1.8%; 95% CI: -3.3, -0.2), and EFW (-2.1%; 95% CI: -3.7, -0.2). A less consistent pattern of association was observed for FL. The negative association of this exposure with BPD and EFW was significantly stronger in smoking versus nonsmoking mothers. __Conclusi