Gas phase Elemental abundances in Molecular cloudS (GEMS) II. On the quest for the sulphur reservoir in molecular clouds: the H2S case.

CONTEXT: Sulphur is one of the most abundant elements in the Universe. Surprisingly, sulphuretted molecules are not as abundant as expected in the interstellar medium and the identity of the main sulphur reservoir is still an open question. AIMS: Our goal is to investigate the H2S chemistry in dark clouds, as this stable molecule is a potential sulphur reservoir. METHODS: Using millimeter observations of CS, SO, H2S, and their isotopologues, we determine the physical conditions and H2S abundances along the cores TMC 1-C, TMC 1-CP, and Barnard 1b. The gas-grain model Nautilus is used to model the sulphur chemistry and explore the impact of photo-desorption and chemical desorption on the H2S abundance. RESULTS: Our modeling shows that chemical desorption is the main source of gas-phase H2S in dark cores. The measured H2S abundance can only be fitted if we assume that the chemical desorption rate decreases by more than a factor of 10 when n H > 2 × 104. This change in the desorption rate is consistent with the formation of thick H2O and CO ice mantles on grain surfaces. The observed SO and H2S abundances are in good agreement with our predictions adopting an undepleted value of the sulphur abundance. However, the CS abundance is overestimated by a factor of 5 - 10. Along the three cores, atomic S is predicted to be the main sulphur reservoir. CONCLUSIONS: The gaseous H2S abundance is well reproduced, assuming undepleted sulphur abundance and chemical desorption as the main source of H2S. The behavior of the observed H2S abundance suggests a changing desorption efficiency, which would probe the snowline in these cold cores. Our model, however, highly overestimates the observed gas-phase CS abundance. Given the uncertainty in the sulphur chemistry, we can only conclude that our data are consistent with a cosmic elemental S abundance with an uncertainty of a factor of 10.

Gas phase Elemental abundances in Molecular cloudS (GEMS): I. The prototypical dark cloud TMC 1.

GEMS is an IRAM 30m Large Program whose aim is determining the elemental depletions and the ionization fraction in a set of prototypical star-forming regions. This paper presents the first results from the prototypical dark cloud TMC 1. Extensive millimeter observations have been carried out with the IRAM 30m telescope (3 mm and 2 mm) and the 40m Yebes telescope (1.3 cm and 7 mm) to determine the fractional abundances of CO, HCO+, HCN, CS, SO, HCS+, and N2H+ in three cuts which intersect the dense filament at the well-known positions TMC 1-CP, TMC 1-NH3, and TMC 1-C, covering a visual extinction range from A V ~ 3 to ~20 mag. Two phases with differentiated chemistry can be distinguished: i) the translucent envelope with molecular hydrogen densities of 1-5×103 cm-3; and ii) the dense phase, located at A V > 10 mag, with molecular hydrogen densities >104 cm-3. Observations and modeling show that the gas phase abundances of C and O progressively decrease along the C+/C/CO transition zone (A V ~ 3 mag) where C/H ~ 8×10-5 and C/O~0.8-1, until the beginning of the dense phase at A V ~ 10 mag. This is consistent with the grain temperatures being below the CO evaporation temperature in this region. In the case of sulfur, a strong depletion should occur before the translucent phase where we estimate a S/H ~ (0.4 - 2.2) ×10-6, an abundance ~7-40 times lower than the solar value. A second strong depletion must be present during the formation of the thick icy mantles to achieve the values of S/H measured in the dense cold cores (S/H ~8×10-8). Based on our chemical modeling, we constrain the value of ζ H2 to ~ (0.5 - 1.8) ×10-16 s-1 in the translucent cloud.

Revisiting the case of R Monocerotis: Is CO removed at R < 20 au?⋆.

CONTEXT: To our knowledge, R Mon is the only B0 star in which a gaseous Keplerian disk has been detected. However, there is some controversy about the spectral type of R Mon. Some authors propose that it could be a later B8e star, where disks are more common. AIMS: Our goal is to re-evaluate the R Mon spectral type and characterize its protoplanetary disk. METHODS: The spectral type of R Mon has been re-evaluated using the available continuum data and UVES emission lines. We used a power-law disk model to fit previous 12CO 1→0 and 2→1 interferometric observations and the PACS CO data to investigate the disk structure. Interferometric detections of 13CO J=1→0, HCO+ 1→0, and CN 1→0 lines using the IRAM Plateau de Bure Interferometer (PdBI) are presented. The HCN 1→0 line was not detected. RESULTS: Our analysis confirms that R Mon is a B0 star. The disk model compatible with the 12CO 1→0 and 2→1 interferometric observations falls short of predicting the observed fluxes of the 1431 CO lines suggest the existence of a region empty of CO at R≲20 au in the proto-planetary disk. The intense emission of the HCO+ and CN lines shows the strong influence of UV photons on gas chemistry. CONCLUSIONS: The observations gathered in this paper are consistent with the presence of a transition disk with a cavity of R in ≳20 au around R Mon. This size is similar to the photoevaporation radius that supports the interpretation that UV photoevaporation is main disk dispersal mechanism in massive stars.

Astrochemical evolution along star formation: Overview of the IRAM Large Program ASAI.

Evidence is mounting that the small bodies of our Solar System, such as comets and asteroids, have at least partially inherited their chemical composition from the first phases of the Solar System formation. It then appears that the molecular complexity of these small bodies is most likely related to the earliest stages of star formation. It is therefore important to characterize and to understand how the chemical evolution changes with solar-type protostellar evolution. We present here the Large Program "Astrochemical Surveys At IRAM" (ASAI). Its goal is to carry out unbiased millimeter line surveys between 80 and 272 GHz of a sample of ten template sources, which fully cover the first stages of the formation process of solar-type stars, from prestellar cores to the late protostellar phase. In this article, we present an overview of the surveys and results obtained from the analysis of the 3 mm band observations. The number of detected main isotopic species barely varies with the evolutionary stage and is found to be very similar to that of massive star-forming regions. The molecular content in O- and C- bearing species allows us to define two chemical classes of envelopes, whose composition is dominated by either a) a rich content in O-rich complex organic molecules, associated with hot corino sources, or b) a rich content in hydrocarbons, typical of Warm Carbon Chain Chemistry sources. Overall, a high chemical richness is found to be present already in the initial phases of solar-type star formation.

Laboratory measurements and astronomical search for cyanomethanimine.

CONTEXT: C-cyanomethanimine (HNCHCN), existing in the two Z and E isomeric forms, is a key prebiotic molecule, but, so far, only the E isomer has been detected toward the massive star-forming region. Sagittarius B2(N) using transitions in the radio wavelength domain. AIMS: With the aim of detecting HNCHCN in Sun-like-star forming regions, the laboratory investigation of its rotational spectrum has been extended to the millimeter-/submillimeter-wave (mm-/submm-) spectral window in which several unbiased spectral surveys have been already carried out. METHODS: High-resolution laboratory measurements of the rotational spectrum of C-cyanomethanimine were carried out in the 100-420 GHz range using a frequency-modulation absorption spectrometer. We then searched for the C-cyanomethanimine spectral features in the mm-wave range using the high-sensitivity and unbiased spectral surveys obtained with the IRAM 30-m antenna in the ASAI context, the earliest stages of star formation from starless to evolved Class I objects being sampled. RESULTS: For both the Z and E isomers, the spectroscopic work has led to an improved and extended knowledge of the spectroscopic parameters, thus providing accurate predictions of the rotational signatures up to ~700 GHz. So far, no C-cyanomethanimine emission has been detected toward the ASAI targets, and upper limits of the column density of ~ 1011-1012 cm-2 could only be derived. Consequently, the C-cyanomethanimine abundances have to be less than a few 10-10 for starless and hot-corinos. A less stringent constraint, ≤ 10-9, is obtained for shocks sites. CONCLUSIONS: The combination of the upper limits of the abundances of C-cyanomethanimine together with accurate laboratory frequencies up to ~ 700 GHz poses the basis for future higher sensitivity searches around Sun-like-star forming regions. For compact (typically less than 1″) and chemically enriched sources such as hot-corinos, the use of interferometers as NOEMA and ALMA in their extended configurations are clearly needed.

Discovery of the Ubiquitous Cation NS+ in Space Confirmed by Laboratory Spectroscopy.

We report the detection in space of a new molecular species which has been characterized spectroscopically and fully identified from astrophysical data. The observations were carried out with the 30m IRAM telescopea. The molecule is ubiquitous as its J=2→1 transition has been found in cold molecular clouds, prestellar cores, and shocks. However, it is not found in the hot cores of Orion-KL and in the carbon-rich evolved star IRC+10216. Three rotational transitions in perfect harmonic relation J' = 2/3/5 have been identified in the prestellar core B1b. The molecule has a 1Σ electronic ground state and its J=2→1 transition presents the hyperfine structure characteristic of a molecule containing a nucleus with spin 1. A careful analysis of possible carriers shows that the best candidate is NS+. The derived rotational constant agrees within 0.3-0.7% with ab initio calculations. NS+ was also produced in the laboratory to unambiguously validate the astrophysical assignment. The observed rotational frequencies and determined molecular constants confirm the discovery of the nitrogen sulfide cation in space. The chemistry of NS+ and related nitrogen-bearing species has been analyzed by means of a time-dependent gas phase model. The model reproduces well the observed NS/NS+ abundance ratio, in the range 30-50, and indicates that NS+ is formed by reactions of the neutral atoms N and S with the cations SH+ and NH+, respectively.

Ionization fraction and the enhanced sulfur chemistry in Barnard 1.

CONTEXT: Barnard B1b has revealed as one of the most interesting globules from the chemical and dynamical point of view. It presents a rich molecular chemistry characterized by large abundances of deuterated and complex molecules. Furthermore, it hosts an extremely young Class 0 object and one candidate to First Hydrostatic Core (FHSC) proving the youth of this star forming region. AIMS: Our aim is to determine the cosmic ray ionization rate, [Formula: see text], and the depletion factors in this extremely young star forming region. These parameteres determine the dynamical evolution of the core. METHODS: We carried out a spectral survey towards Barnard 1b as part of the IRAM Large program ASAI using the IRAM 30-m telescope at Pico Veleta (Spain). This provided a very complete inventory of neutral and ionic C-, N- and S- bearing species with, up to our knowledge, the first secure detections of the deuterated ions DCS+ and DOCO+. We use a state-of-the-art pseudo-time-dependent gas-phase chemical model that includes the ortho and para forms of [Formula: see text] and [Formula: see text] to determine the local value of the cosmic ray ionization rate and the depletion factors. RESULTS: Our model assumes n(H2)=105 cm-3 and T k =12 K, as derived from our previous works. The observational data are well fitted with ζH2 between 3×10-17 s-1 and 10-16 s-1, and the following elemental abundances: O/H=3 10-5, N/H=6.4-8 10-5, C/H=1.7 10-5 and S/H between 6.0 10-7 and 1.0 10-6. The large number of neutral/protonated species detected, allows us to derive the elemental abundances and cosmic ray ionization rate simultaneously. Elemental depletions are estimated to be ~10 for C and O, ~1 for N and ~25 for S. CONCLUSIONS: Barnard B1b presents similar depletions of C and O than those measured in pre-stellar cores. The depletion of sulfur is higher than that of C and O but not as extreme as in cold cores. In fact, it is similar to the values found in some bipolar outflows, hot cores and photon-dominated regions. Several scenarios are discussed to account for these peculiar abundances. We propose that it is the consequence of the initial conditions (important outflows and enhanced UV fields in the surroundings) and a rapid collapse (~0.1 Myr) that permits to maintain most S- and N-bearing species in gas phase to great optical depths. The interaction of the compact outflow associated with B1b-S with the surrounding material could enhance the abundances of S-bearing molecules, as well.

High spatial resolution imaging of SO and H2CO in AB Auriga: The first SO image in a transitional disk.

CONTEXT: Transitional disks are structures of dust and gas around young stars with large inner cavities in which planet formation may occur. Lopsided dust distributions are observed in the dust continuum emission at millimeter wavelengths. These asymmetrical structures can be explained as being the result of an enhanced gas density vortex where the dust is trapped, potentially promoting the rapid growth to the planetesimal scale. AIMS: AB Aur hosts a transitional disk with a clear horseshoe morphology which strongly suggests the presence of a dust trap. Our goal is to investigate its formation and the possible effects on the gas chemistry. METHODS: We used the NOEMA (NOrthern Extended Millimeter Array) interferometer to image the 1mm continuum dust emission and the 13CO J=2 →1, C18OJ=2 →1, SO J=56 →45, and H2CO J=303 →202 rotational lines. RESULTS: Line integrated intensity ratio images are built to investigate the chemical changes within the disk. The I(H2CO J=303 →202)/I(C18O J=2→1) ratio is fairly constant along the disk with values of ~0.15±0.05. On the contrary, the I(SO J=56 →45)/I(C18O J=2 →1) and I(SO J=56 →45)/I(H2CO J=303 →202) ratios present a clear northeast-southwest gradient (a factor of 3-6) with the minimum towards the dust trap. This gradient cannot be explained by a local change in the excitation conditions but by a decrease in the SO abundance. Gas densities up to ~109 cm-3 are expected in the disk midplane and two-three times larger in the high pressure vortex. We have used a single point (n,T) chemical model to investigate the lifetime of gaseous CO, H2CO, and SO in the dust trap. Our model shows that for densities >107 cm-3, the SO molecules are depleted (directly frozen, or converted into SO2 and then frozen out) in less than 0.1 Myr. The lower SO abundance towards the dust trap could indicate that a larger fraction of the gas is in a high density environment. CONCLUSIONS: Gas dynamics, grain growth and gas chemistry are coupled in the planet formation process. We detect a chemical signature of the presence of a dust trap in a transitional disk. Because of the strong dependence of SO abundance on the gas density, the sulfur chemistry can be used as a chemical diagnostic to detect the birthsites of future planets. However, the large uncertainties inherent to chemical models and the limited knowledge of the disk's physical structure and initial conditions are important drawbacks.

The rs10401670 variant in resistin gene improved insulin resistance response and metabolic parameters secondaries to weight loss after a hypocaloric diet.

BACKGROUND: The SNP 3'UTR C/T (rs10401670), it is a polymorphism that has been associated with diabetes mellitus and it has been scarcely studied before. As far as we know, no studies on interaction among diet intervention, rs10401670 variant of RETN and metabolic response has been realized. OBJECTIVE: Our aim was to analyze the effects of the rs10401670 RETN gene polymorphism on insulin resistance response and metabolic changes secondary to weight loss after 3 months of a hypocaloric diet in adults obese patients without diabetes mellitus. DESIGN: A Caucasian population of 135 obese patients without diabetes mellitus was analyzed. Before and after 3 months on a low fat hypocaloric diet, an anthropometric evaluation, an assessment of nutritional intake and a biochemical analysis were performed. The statistical analysis was performed for the combined CT and TT as a group (minor allele group) and wild type CC as second group (major allele group) (dominant model). RESULTS: Forty nine patients (36.3%) had the genotype CC (major allele group) and 86 (63.7%) patients had the next genotypes; CT (67 patients, 49.6%) or TT (19 patients, 14.1%) (minor allele group). After dietary treatment and in major allele group, weight, BMI, fat mass, systolic blood pressure and waist circumference decreases were similar than minor allele group. In T allele carriers, fasting plasma glucose, insulin, HOMA-IR, total cholesterol and LDL cholesterol levels decreased significantly. In non T allele carriers and after dietary treatment, only LDL cholesterol and total cholesterol decreased. In non T Allele carriers, the decrease in total cholesterol was -15.1 ± 18.3 mg/dl (decrease in T Allele carriers -18.3 ± 15.7 mg/dl: p > 0.05), LDL-cholesterol was -14.3 ± 18.5 mg/dl (decrease in T Allele carriers -17.3 ± 10.1 mg/dl:p > 0.05), fasting glucose plasma -2.2 ± 1.5 mg/dL (decrease in T Allele carriers -4.8 ± 1.2 mg/dL: p = 0.02), insulin -1.1 ± 2.0 mUI/L (decrease in T Allele carriers -6.3 ± 1.9 mUI/L: p = 0.001) and HOMA-IR -0.2 ± 1.0 (decrease in T Allele carriers -1.8 ± 1.4: p = 0.005). Leptin levels decrease in both genotypes after dietary treatment (-21.1 ± 8.5 ng/dL in nonT Allele carriers vs -16.2 ± 10.2 ng/dL in T Allele carriers:p > 0.05). Resistin remained unchanged in both groups. CONCLUSION: In our study in non-diabetic obese subjects, we describe an association of rs10401670T allele with a better metabolic response (glucose, insulin and HOMA-IR) secondary to weight loss with a hypocaloric diet.

Role of rs6923761 gene variant in glucagon-like peptide 1 receptor in basal GLP-1 levels, cardiovascular risk factor and serum adipokine levels in naïve type 2 diabetic patients.

BACKGROUND: Role of GLP-1 variants on basal GLP-1 levels, body weight and cardiovascular risk factors remains unclear in patients with diabetes mellitus type 2. OBJECTIVE: Our aim was to analyze the effects of rs6923761 GLP-1 receptor polymorphism on body weight, cardiovascular risk factors, basal GLP-1 levels and serum adipokine levels in naïve patients with diabetes mellitus type 2. DESIGN: A sample of 104 naïve patients with diabetes mellitus type 2 was enrolled in a prospective way. Basal fasting glucose, c-reactive protein (CRP), insulin, insulin resistance (HOMA), total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides concentration, basal GLP-1, HbA1c and adipokines (leptin, adiponectin, resistin) levels were determined. Weights, body mass index, waist circumference, fat mass by bioimpedance and blood pressure measures were measured. RESULTS: Forty-nine patients (47.1%) had the genotype GG and 55 (52.9%) diabetic subjects had the next genotypes; GA (44 patients, 42.3%) or AA (11 study subjects, 10.6%) (second group). In A allele carriers, basal GLP-1 levels were higher than non-carriers (2.9 ± 2.1 ng/ml; p < 0.05). No differences were detected between both genotype groups. CONCLUSION: Our cross-sectional study revealed an association between the rs6923761 GLP-1 receptor polymorphism (A allele carriers) and basal GLP-1 levels in naïve patients with diabetes mellitus type 2.

Cardiovascular risk factors and adipocytokines levels after two hypocaloric diets with different fat distribution in obese subjects and rs6923761 gene variant of glucagon-like peptide 1 receptor.

BACKGROUND: The role of GLP-1 R variants on body weight response after dietary intervention is unclear. OBJECTIVE: Our aim was to evaluate the effect of this polymorphism on cardiovascular risk factors, adipokine levels and weight loss secondary to a high monounsaturated fat vs. a high polyunsaturated fat hypocaloric diets in obese subjects. DESIGN: 391 obese subjects were randomly allocated to one of these two diets for a period of 3 months; diet M (high monounsaturated fat hypocaloric diet) and diet P (high polyunsaturated (PUFAs) fat hypocaloric diet). RESULTS: Two hundred and twelve patients (54.2 %) had the genotype GG (wild group) and 179 (45.8 %) patients had the next genotypes; GA (146 patients, 37.3 %) or AA (33 patients, 8.7 %) (Mutant group). With both diets and in wild-type and mutant-type groups, BMI, weight, fat mass, waist circumference and systolic blood pressure decreased. Anthropometric parameters were higher in non-A-allele carriers than A-allele carriers. With both diets and in both genotypes, leptin, insulin levels and HOMA decreased. With the diet P and in wild genotype, total cholesterol and LDL-cholesterol levels decreased, too. CONCLUSION: Our data showed a lack of association of rs6923761 GLP-1 R polymorphism with weight loss after a high monounsaturated fat and a high polyunsaturated fat hypocaloric diets. Better anthropometric parameters in obese subjects with the mutant allele (A) of rs6923761 GLP-1 R polymorphism were observed. Insulin levels and HOMA decreased in non-A carriers.

Effect of a high monounsaturated vs high polyunsaturated fat hypocaloric diets in nonalcoholic fatty liver disease.

OBJECTIVE: Hyperaminotransferasemia is an important problem in obese patients. We decide to examine the changes in hyperaminotransferasemia after weight reduction in obese patients with and without NAFLD secondary to a high monounsaturated fat vs. a high polyunsaturated fat hypocaloric diets. PATIENTS AND METHODS: A population of 306 obese patients was randomly allocated to two groups: Diet M (high monounsaturated fat hypocaloric diet) and Diet P (high polyunsaturated fat hypocaloric diet). Patients were classified as group I (obese subjects; n=262) when serum ALT activity was normal or group II (NAFLD patients; n=44) when serum ALT activity was (≥ 43 UI/L). RESULTS: In NAFLD group with diet M, BMI, weight, fat mass, waist circumference, systolic blood pressure, total cholesterol, LDL cholesterol), insulin and HOMA-R decreased. In NAFLD group with diet P, BMI, weight, fat mass, waist circumference, systolic blood pressure, total cholesterol, LDL cholesterol), insulin and HOMA-R decreased, too. In NAFLD group, alanine aminotransferase [(diet M) -20.3±19.2 UI/L vs. (diet P) -14.2±20.1 UI/L], aspartate aminotransferase [(diet M) -11.3±12.2 UI/L vs. (diet P) -11.1±10.1 UI/L], and gammaglutamyl transferase [(diet M) -18.1±12.2 UI/L vs. (diet P) -10.9±20.1 UI/L] improved with both diets. CONCLUSIONS: We showed that weight reduction secondary to two hypocaloric diets was associated with improvement in hypertransaminasemia and insulin resistance in NAFLD patients.

Respuesta inmune respiratoria al año de vida en el niño prematuro / Respiratory immune response in first year of a preterm infant

Introducción: Existe un gran desconocimiento acerca de la evolución del sistema inmune en la mucosa respiratoria del niño prematuro a largo plazo. La inmadurez y las infecciones respiratorias pueden influir sobre la respuesta inmune de las mucosas. El propósito de este estudio era evaluar la secreción respiratoria de los mediadores inmunológicos al año de vida en niños prematuros. Pacientes y métodos: Desde octubre de 2008 hasta abril de2009 se reclutaron 77 prematuros nacidos en 6 servicios de pediatría de Castilla y León, así como 14 controles sanos a término. Los prematuros fueron citados al año de edad gestacional corregida y los niños a término al año de vida, momento en el cual se les realizó un lavado nasal para determinar los niveles de 27 mediadores inmunológicos mediante un ensayo de Biorad®. Resultados: Los niños prematuros tenían niveles más elevados de quimiocinas (eotaxina, IP-10), citocinas Th-1 (IFN-epsilon), Th-2 (IL-13), Th-17 (IL-17) y factores de crecimiento celular (PDGF-bb, VEGF, FGF-b, G-CSF y GM-CSF) que los niños a término. Cuando se compararon los niveles de mediadores entre los niños que habían recibido profilaxis para el virus respiratorios incitial con palivizumab y los que no, los segundos tenían niveles significativamente más altos de MCP-1, IL-1RA, IL-10,IL-12p70 y VEGF (p <0,05) que los primeros. Conclusiones: Este trabajo demuestra por vez primera la influencia de la prematuridad sobre los perfiles de secreción respiratoria de las citocinas y quimiocinas a largo plazo. Por otra parte, nuestros resultados indican que la evaluación del impacto de la profilaxis de la infección respiratoria es un camino interesante para comprender la maduración de la respuesta inmune de la mucosa respiratoria del prematuro(AU)

Introduction: There is a big unawareness about a long term respiratory mucous immune system evolution in the preterm infant. Immaturity and respiratory infections can have a big influence on the mucous immune responses. This investigation’s purpose is the evaluation of respiratory secretion of inflammatory immunological mediators in the first year of a preterm infant. Patients and methods: Between October 2008 and April 2009, 77 preterm infants were born in 6 pediatric services of Castilla y Leon, plus to another 14 healthy controls results. Children were invited on their first corrected gestational age and the ones of healthy controls results. Nasal washing were applied to determine 27 immunological mediators’ levels by applying a Biorad test. Results: The preterm infants has higher chemokine (eotaxin,IP-10), cytokines Th-1 (IFN-epsilon), Th-2 (IL-13), Th-17 (IL-17) and cell growing factors (PDGF-bb, VEGF, FGF-b, G-CSF and GM-CSF)levels than a healthy control results children. When a comparison was made between children that received prophylaxis for their respiratory syncytial virus with palivizumab and the ones that did not receive it, the second group showed higher MCP-1, IL-1RA, IL-10, IL-12p70 and VEGF (p <0,05) levels. Conclusions: This work proves, for the first time, the influence of the premature birth on chemokine and cytokines respiratory secretion levels in a long term concepts. On other hand, our results indicate that prophylaxis impact in the respiratory infection is an interesting way to understand respiratory mucous immune response maturation in the preterm infant(AU)

Fibronectin in meningococcal sepsis. Correlation with antithrombin III and protein C.

Plasma fibronectin was measured with Laurell's immunoelectroassay in 44 patients with meningococcal sepsis. The average value (15.0 +/- 7.9 mg/dl) was lower than that in normal children (27.4 +/- 8.7 mg/dl) (p less than 0.001). Fibronectin in patients correlated positively with antithrombin III (AT-III) values (p less than 0.02), but not with protein C (0.05 less than p less than 0.1). The decrease of fibronectin had no prognostic value. The fibronectin levels were lower in patients with disseminated intravascular coagulation (DIC+), than in those without DIC (DIC-) (p less than 0.02), but were lower in both groups than in a normal control group. A negative correlation between fibronectin and protein C was only present in DIC- patients (r: -0.773 = p less than 0.01). Fibronectin varied independent of AT-III and protein C in DIC+ patients. The study was repeated in 11 patients 24 hours after admission when fibronectin had decreased in 7/11 cases (mean decrease: -2.7 +/- 8.7 mg/dl). This variation correlated in a negative way with AT-III (r: -0.659 = p less than 0.05). In meningococcal sepsis fibronectin decreases very early, even in DIC- patients and its relationship to AT-III and protein C is different, depending on the presence of DIC and on the stage of evolution of the disease.

Deficient activity of prostacyclin stimulating plasma factor (PSPF) in newborns.

The activity of PSPF was studied in 38 normal newborns. The production of 6-keto-PGF1 (PGI2 stable metabolite) after stimulation with cord blood plasma, 0.72 +/- 0.50 pmol/10(5) cells, was lesser than after stimulation with plasma from 2-3 years old children, 3.00 +/- 0.89 pmol/10(5) cells (p less than 0.01), or from adults, 7.74 +/- 5.00 pmol/10(5) cells (p less than 0.001). No differences were shown during neonatal period. The presence of a circulating inhibitor factor in newborns was dismissed by mixed cultures. The behaviour of neonatal plasma after consecutive stimulations with AA was similar to adult plasma response. We proved that newborns show a deficient capacity to stimulate PGI2, which is not due to circulating inhibitor factor, and we think that this deficiency is due to a weaker action of stimuli, rather than to an immaturity.