The N-fixing legume Periandra mediterranea constrains the invasion of an exotic grass (Melinis minutiflora P. Beauv) by altering soil N cycling

Melinis minutiflora is an invasive species that threatens the biodiversity of the endemic vegetation of the campo rupestre biome in Brazil, displacing the native vegetation and favouring fire spread. As M. minutiflora invasion has been associated with a high nitrogen (N) demand, we assessed changes in N cycle under four treatments: two treatments with contrasting invasion levels (above and below 50%) and two un-invaded control treatments with native vegetation, in the presence or absence of the leguminous species Periandra mediterranea. This latter species was considered to be the main N source in this site due to its ability to fix N2 in association with Bradyrhizobia species. Soil proteolytic activity was high in treatments with P. mediterranea and in those severely invaded, but not in the first steps of invasion. While ammonium was the N-chemical species dominant in plots with native species, including P.mediterranea, soil nitrate prevailed only in fully invaded plots due to the stimulation of the nitrifying bacterial (AOB) and archaeal (AOA) populations carrying the amoA gene. However, in the presence of P. mediterranea, either in the beginning of the invasion or in uninvaded plots, we observed an inhibition of the nitrifying microbial populations and nitrate formation, suggesting that this is a biotic resistance strategy elicited by P. mediterranea to compete with M. minutiflora. Therefore, the inhibition of proteolytic activity and the nitrification process were the strategies elicited by P.mediterranea to constrain M.munitiflora invasion

Pharmacokinetic–pharmacodynamic modelling of the analgesic effects of lumiracoxib, a selective inhibitor of cyclooxygenase-2, in rats

Background and purpose: This study establishes a pharmacokinetic/pharmacodynamic (PK/PD) model to describe the time course and in vivo mechanisms of action of the antinociceptive effects of lumiracoxib, evaluated by the thermal hyperalgesia test in rats. Experimental approach: Female Wistar fasted rats were injected s.c. with saline or carrageenan in the right hind paw, followed by either 0, 1, 3, 10 or 30 mg·kg-1 of oral lumiracoxib at the time of carrageenan injection (experiment I), or 0, 10 or 30 mg·kg-1 oral lumiracoxib at 4 h after carrageenan injection (experiment II). Antihyperalgesic responses were measured as latency time (LT) to a thermal stimulus. PK/PD modelling of the antinociceptive response was performed using the population approach with NONMEM VI. Results: A two-compartment model described the plasma disposition. A first-order model, including lag time and decreased relative bioavailability as a function of the dose, described the absorption process. The response model was: LT = LT0/(1 + MED). LT0 is the baseline response, and MED represents the level of inflammatory mediators. The time course of MED was assumed to be equivalent to the predicted profile of COX-2 activity and was modelled according to an indirect response model with a time variant synthesis rate. Drug effects were described as a reversible inhibition of the COX-2 activity. The in vivo estimate of the dissociation equilibrium constant of the COX-2-lumiracoxib complex was 0.24 mg·mL-1. Conclusions: The model developed appropriately described the time course of pharmacological responses to lumiracoxib, in terms of its mechanism of action and pharmacokinetics

First Stars. I. Evolution without mass loss

The first generation of stars was formed from primordial gas. Numerical simulations suggest that the first stars were predominantly very massive, with typical masses M > 100 Mo. These stars were responsible for the reionization of the universe, the initial enrichment of the intergalactic medium with heavy elements, and other cosmological consequences. In this work, we study the structure of Zero Age Main Sequence stars for a wide mass and metallicity range and the evolution of 100, 150, 200, 250 and 300 Mo galactic and pregalactic Pop III very massive stars without mass loss, with metallicity Z=10E-6 and 10E-9, respectively. Using a stellar evolution code, a system of 10 equations together with boundary conditions are solved simultaneously. For the change of chemical composition, which determines the evolution of a star, a diffusion treatment for convection and semiconvection is used. A set of 30 nuclear reactions are solved simultaneously with the stellar structure and evolution equations. Several results on the main sequence, and during the hydrogen and helium burning phases, are described. Low metallicity massive stars are hotter and more compact and luminous than their metal enriched counterparts. Due to their high temperatures, pregalactic stars activate sooner the triple alpha reaction self-producing their own heavy elements. Both galactic and pregalactic stars are radiation pressure dominated and evolve below the Eddington luminosity limit with short lifetimes. The physical characteristics of the first stars have an important influence in predictions of the ionizing photon yields from the first luminous objects; also they develop large convective cores with important helium core masses which are important for explosion calculations.Comment: 17 pages, 24 figures, 2 table

Pancreatic window and open necrosectomy; a surgical alternative for walled-off pancreatic necrosis in a second level hospital in Mexico

Walled-off pancreatic necrosis is defined as a necrotic collection with a defined wall, which generally occurs in 15% of patients in the fourth week after acute pancreatitis. Actually, open surgery is reserved for selected cases, with minimally invasive treatments such as image-assisted percutaneous drainage or endoscopic ultrasound being the procedures of choice. However, in developing countries the open approach continues to be an effective therapeutic alternative. We present the case of a 47-year-old male patient with no significant history who developed severe acute pancreatitis secondary to hypertriglyceridemia and who later developed walled-off pancreatic necrosis as a late complication. As a treatment, a debridement of the necrotic tissue with marsupialization was performed using the bradley III technique, secondary to the procedure, a pancreatic fistula was developed. After 8 weeks of hospitalization, in which he had a favourable response to surgical treatment, with spontaneous closure of the fistula without complications. Surgical management of late complications of acute pancreatitis remains controversial. Although minimally invasive procedures are the first option nowadays, in developing countries, open necrosectomy remains a good option for the treatment of these types of complications

Mucosa-associated lymphoid tissue lymphoma of the appendix stump: a case report

Primary lymphomas of the appendix occur in 0.015% of all gastrointestinal lymphomas. The most common manifestation is acute appendicitis secondary to luminal obstruction. The most common is immunophenotype B low-grade non-Hodgkin lymphoma. A 53-year-old male, with a previous three-week surgical history due to acute appendicitis, histopathological report of acute appendicitis and lymphoid hyperplasia. Later, he was admitted, with abdominal pain in the right iliac fossa, an abdominal ultrasound and simple abdominal tomography were performed, with suspicion of residual abscess. Surgical intervention is decided, observing paracecal tumor in the emergency site of the appendix, the tumor is removed. Pathological study that reports an appendicular base infiltrated by mucosa-associated lymphoma. The diagnosis of appendicular tumors is mostly, intraoperatively incidental. It is necessary to have the diagnostic possibility when performing an appendectomy, since it changes the prognosis and treatment of the patient

First Stars. II. Evolution with mass loss

The first stars are assumed to be predominantly massive. Although, due to the low initial abundances of heavy elements the line-driven stellar winds are supposed to be inefficient in the first stars, these stars may loose a significant amount of their initial mass by other mechanisms. In this work, we study the evolution with a prescribed mass loss rate of very massive, galactic and pregalactic, Population III stars, with initial metallicities $Z=10^{-6}$ and $Z=10^{-9}$, respectively, and initial masses 100, 120, 150, 200, and 250$\,M_{\odot}$ during the hydrogen and helium burning phases. The evolution of these stars depends on their initial mass, metallicity and the mass loss rate. Low metallicity stars are hotter, compact and luminous, and they are shifted to the blue upper part in the Hertzprung-Russell diagram. With mass loss these stars provide an efficient mixing of nucleosynthetic products, and depending on the He-core mass their final fate could be either pair-instability supernovae or energetic hypernovae. These stars contributed to the reionization of the universe and its enrichment with heavy elements, which influences the subsequent star formation properties.Comment: Accepted for publication in Astrophysics & Space Science. 15 pages, 18 figure

Rosiglitazone as an option for patients with acromegaly: a case series

<p>Abstract</p> <p>Introduction</p> <p>In the patient with acromegaly, pituitary surgery is the therapeutic standard. Despite undergoing surgery, a significant number of patients with acromegaly continue to have uncontrolled growth hormone secretion. These patients require other treatments such as external irradiation and/or drug therapy.</p> <p>Case presentation</p> <p>We present the clinical and laboratory responses to six months of treatment with rosiglitazone in four cases. In all four cases, the patients had persistent growth hormone overproduction despite previous surgical treatment and other conventional therapy. Case 1 is a 57-year-old Caucasian woman, case 2 is a 51-year-old Hispanic man, case 3 is a 32-year-old Hispanic woman, and case 4 is a 36-year-old Hispanic man. In three of these patients, basal and nadir growth hormone and insulin-like growth factor 1 levels were significantly decreased (<it>P </it>< 0.05 and <it>P </it>< 0.01, respectively).</p> <p>Conclusion</p> <p>Rosiglitazone could be a treatment option in select patients with acromegaly.</p

Rhizobium Promotes Non-Legumes Growth and Quality in Several Production Steps: Towards a Biofertilization of Edible Raw Vegetables Healthy for Humans

The biofertilization of crops with plant-growth-promoting microorganisms is currently considered as a healthy alternative to chemical fertilization. However, only microorganisms safe for humans can be used as biofertilizers, particularly in vegetables that are raw consumed, in order to avoid sanitary problems derived from the presence of pathogenic bacteria in the final products. In the present work we showed that Rhizobium strains colonize the roots of tomato and pepper plants promoting their growth in different production stages increasing yield and quality of seedlings and fruits. Our results confirmed those obtained in cereals and alimentary oil producing plants extending the number of non-legumes susceptible to be biofertilized with rhizobia to those whose fruits are raw consumed. This is a relevant conclusion since safety of rhizobia for human health has been demonstrated after several decades of legume inoculation ensuring that they are optimal bacteria for biofertilization