Effects of the humic acid extracted from vermicompost on the germination and initial growth of Brachiaria brizantha cv. MG5

The biological effects of humic substances on vegetables depend on the source of extraction and the concentration used, on the vegetable species and on the age of the plant. This study aimed to evaluate the effect of different humic acid (HA) doses extracted from vermicompost on the germination and initial growth of Brachiaria brizantha cv. MG5. To that end, germination tests were conducted in germination agents, as well as emergence test in greenhouse and seedlings growth test for those agents. For all these tests, five doses of HA [0.0; 1.0; 2.0; 4.0 e 8.0 mM C.L-1] were used, with and without reapplying HA. The following characteristics were analyzed: percentage of germination, percentage of normal seedlings in the first counting of the germination test, percentage of abnormal seedlings, percentage of non-germinated seedlings, percentage of emergence, emergence speed rates, fresh and dry matter of the upper and roots part, length of the upper and roots part and number of lateral roots. Positive effect of HA reapplication in the percentage of abnormal seedlings was observed. With increasing doses of HA, there was a reduction in the percentage of germination and normal seedlings in the first count. The application of HA promoted increase in shoot length and number of lateral root. There was no significant difference in the length of the root. Humus acid affects positively the initial growth of B. brizantha cv. MG5, with the best stimulation being observed when the 2.0 mM C.L-1 dose was applied.Keywords: Forage, Urochloa sp., vigor.Abbreviation: HA, Humic acid

Effects of Vagal Stimulation on Induction and Termination of Atrial Fibrillation in an in Vivo Rabbit Heart Model

INTRODUCTION: Vagal activity is thought to influence atrial electrophysiological properties and play a role in the initiation and maintenance of atrial fibrillation (AF). In this study, we assessed the effects of acute vagal stimulation (vagus_stim) on atrial conduction times, atrial and pulmonary vein (PV) refractoriness, and vulnerability to induction of AF in the rabbit heart with intact autonomic innervation. METHODS: An open-chest epicardial approach was performed in 11 rabbits (New Zealand; 3.9-5.0 kg), anesthetized and artificially ventilated after neuromuscular blockade. A 3-lead ECG was obtained. Atrial electrograms were recorded along the atria, from right to left (four monopolar electrodes), together with a circular electrode adapted for proximal left PV assessment. Acute vagus nerve stimulation was obtained with bipolar electrodes (20 Hz). Epicardial activation was recorded in sinus rhythm, and the conduction time from right (RA) to left atrium (LA), and from RA to PVs, was measured in basal conditions and during vagus_stim. The atrial effective refractory period (ERP) and dispersion of refractoriness (Disp_A) were analyzed. Vulnerability to AF induction was assessed at the right (RAA) and left (LAA) atrial appendages and the PVs. Atrial stimulation (50 Hz) was performed alone or combined with vagus_stim. Heart rate and blood pressure were monitored. RESULTS: In basal conditions, there was a significant delay in conduction from RA to PVs, not influenced by vagus_stim, and the PV ERPs were shorter than those measured in LA and LAA, but without significant differences compared to RA and RAA. During vagus_stim, conduction times between RA and LA increased from 16+8 ms to 27+6 ms (p 10 s in 45.4% of rabbits during vagus_stim, and ceased after vagus_stim in 4 out of these 5 cases. In 3 animals, PV tachycardia, with fibrillatory conduction, induced with 50 Hz PV pacing during vagus_stim. CONCLUSIONS: Vagus_stim reduces interatrial conduction velocity and significantly shortens atrial ERP, contributing to the induction and duration of AF episodes in the in vivo rabbit heart. This model may be useful for the assessment of autonomic influence on the pathophysiology of AF

Cooperative secretions facilitate host range expansion in bacteria

The majority of emergent human pathogens are zoonotic in origin, that is, they can transmit to humans from other animals. Understanding the factors underlying the evolution of pathogen host range is therefore of critical importance in protecting human health. There are two main evolutionary routes to generalism: organisms can tolerate multiple environments or they can modify their environments to forms to which they are adapted. Here we use a combination of theory and a phylogenetic comparative analysis of 191 pathogenic bacterial species to show that bacteria use cooperative secretions that modify their environment to extend their host range and infect multiple host species. Our results suggest that cooperative secretions are key determinants of host range in bacteria, and that monitoring for the acquisition of secreted proteins by horizontal gene transfer can help predict emerging zoonoses

Mosaic DNA imports with interspersions of recipient sequence after natural transformation of Helicobacter pylori

Helicobacter pylori colonizes the gastric mucosa of half of the human population, causing gastritis, ulcers, and cancer. H. pylori is naturally competent for transformation by exogenous DNA, and recombination during mixed infections of one stomach with multiple H. pylori strains generates extensive allelic diversity. We developed an in vitro transformation protocol to study genomic imports after natural transformation of H. pylori. The mean length of imported fragments was dependent on the combination of donor and recipient strain and varied between 1294 bp and 3853 bp. In about 10% of recombinant clones, the imported fragments of donor DNA were interrupted by short interspersed sequences of the recipient (ISR) with a mean length of 82 bp. 18 candidate genes were inactivated in order to identify genes involved in the control of import length and generation of ISR. Inactivation of the antimutator glycosylase MutY increased the length of imports, but did not have a significant effect on ISR frequency. Overexpression of mutY strongly increased the frequency of ISR, indicating that MutY, while not indispensable for ISR formation, is part of at least one ISR-generating pathway. The formation of ISR in H. pylori increases allelic diversity, and contributes to the uniquely low linkage disequilibrium characteristic of this pathogen

Distinct Binding and Immunogenic Properties of the Gonococcal Homologue of Meningococcal Factor H Binding Protein

Neisseria meningitidis is a leading cause of sepsis and meningitis. The bacterium recruits factor H (fH), a negative regulator of the complement system, to its surface via fH binding protein (fHbp), providing a mechanism to avoid complement-mediated killing. fHbp is an important antigen that elicits protective immunity against the meningococcus and has been divided into three different variant groups, V1, V2 and V3, or families A and B. However, immunisation with fHbp V1 does not result in cross-protection against V2 and V3 and vice versa. Furthermore, high affinity binding of fH could impair immune responses against fHbp. Here, we investigate a homologue of fHbp in Neisseria gonorrhoeae, designated as Gonococcal homologue of fHbp (Ghfp) which we show is a promising vaccine candidate for N. meningitidis. We demonstrate that Gfhp is not expressed on the surface of the gonococcus and, despite its high level of identity with fHbp, does not bind fH. Substitution of only two amino acids in Ghfp is sufficient to confer fH binding, while the corresponding residues in V3 fHbp are essential for high affinity fH binding. Furthermore, immune responses against Ghfp recognise V1, V2 and V3 fHbps expressed by a range of clinical isolates, and have serum bactericidal activity against N. meningitidis expressing fHbps from all variant groups

Treatment of rats with a self-selected hyperlipidic diet, increases the lipid content of the main adipose tissue sites in a proportion similar to that of the lipids in the rest of organs and tissues

Adipose tissue (AT) is distributed as large differentiated masses, and smaller depots covering vessels, and organs, as well as interspersed within them. The differences between types and size of cells makes AT one of the most disperse and complex organs. Lipid storage is partly shared by other tissues such as muscle and liver. We intended to obtain an approximate estimation of the size of lipid reserves stored outside the main fat depots. Both male and female rats were made overweight by 4-weeks feeding of a cafeteria diet. Total lipid content was analyzed in brain, liver, gastrocnemius muscle, four white AT sites: subcutaneous, perigonadal, retroperitoneal and mesenteric, two brown AT sites (interscapular and perirenal) and in a pool of the rest of organs and tissues (after discarding gut contents). Organ lipid content was estimated and tabulated for each individual rat. Food intake was measured daily. There was a surprisingly high proportion of lipid not accounted for by the main macroscopic AT sites, even when brain, liver and BAT main sites were discounted. Muscle contained about 8% of body lipids, liver 1-1.4%, four white AT sites lipid 28-63% of body lipid, and the rest of the body (including muscle) 38-44%. There was a good correlation between AT lipid and body lipid, but lipid in"other organs" was highly correlated too with body lipid. Brain lipid was not. Irrespective of dietary intake, accumulation of body fat was uniform both for the main lipid storage and handling organs: large masses of AT (but also liver, muscle), as well as in the"rest" of tissues. These storage sites, in specialized (adipose) or not-specialized (liver, muscle) tissues reacted in parallel against a hyperlipidic diet challenge. We postulate that body lipid stores are handled and regulated coordinately, with a more centralized and overall mechanisms than usually assumed

Microevolution of Helicobacter pylori during prolonged infection of single hosts and within families

Our understanding of basic evolutionary processes in bacteria is still very limited. For example, multiple recent dating estimates are based on a universal inter-species molecular clock rate, but that rate was calibrated using estimates of geological dates that are no longer accepted. We therefore estimated the short-term rates of mutation and recombination in Helicobacter pylori by sequencing an average of 39,300 bp in 78 gene fragments from 97 isolates. These isolates included 34 pairs of sequential samples, which were sampled at intervals of 0.25 to 10.2 years. They also included single isolates from 29 individuals (average age: 45 years) from 10 families. The accumulation of sequence diversity increased with time of separation in a clock-like manner in the sequential isolates. We used Approximate Bayesian Computation to estimate the rates of mutation, recombination, mean length of recombination tracts, and average diversity in those tracts. The estimates indicate that the short-term mutation rate is 1.4×10−6 (serial isolates) to 4.5×10−6 (family isolates) per nucleotide per year and that three times as many substitutions are introduced by recombination as by mutation. The long-term mutation rate over millennia is 5–17-fold lower, partly due to the removal of non-synonymous mutations due to purifying selection. Comparisons with the recent literature show that short-term mutation rates vary dramatically in different bacterial species and can span a range of several orders of magnitude

Suicidal Thoughts and Behaviors Among Transgender Adults in Relation to Education, Ethnicity, and Income: A Systematic Review

Introduction: This systematic review assessed the impact of race/ethnicity, education, and income on transgender individual's lifetime experience of suicidal thoughts and behaviors (SITB) in gray and published literature (1997–2017). Methods: Sixty four research projects (108 articles) were identified in WorldCat, PubMed, and Google Scholar. Articles were included if they were published in Canada or the United States, included original quantifiable data on transgender SITBs, and had ≥5 participants, at least 51% of whom were ≥18 years. Results: Across all projects suicide ideation averaged 46.55% and attempts averaged 27.19%. The majority of participants were Caucasian, whereas the highest rate of suicide attempts (55.31%) was among First Nations, who accounted for <1.5% of participants. Caucasians, by contrast, had the lowest attempt rate (36.80%). More participants obtained a bachelor's degree and fewer an associate or technical degree than any other level of education. Suicide attempts were highest among those with ≤some high school (50.70%) and lowest among those with an advanced degree (30.25%). More participants made an income of $20–$50,000/year and less $10–$20,000 than any other income bracket. Conclusion: SITBs, among the transgender population, are both universally high and impacted by race/ethnicity, educational attainment, and income. These findings may be useful in creating culturally and factually informed interventions for transgender individuals experiencing SITBs and in informing future research on this topic

Acute Vagal Modulation of Electrophysiology of the Atrial and Pulmonary Veins Increases Vulnerability to Atrial Fibrillation

Vagal activity is thought to influence atrial electrophysiological properties and play a role in the initiation and maintenance of atrial fibrillation (AF). We evaluated the effects of acute vagal stimulation on atrial conduction, refractoriness of atrial and pulmonary veins (PVs) and inducibility of AF. An open-chest epicardial approach was performed in New Zealand White rabbits with preserved autonomic innervation. Atrial electrograms were obtained with four unipolar electrodes placed epicardially along the atria (n = 22) and an electrode adapted to the proximal left PV (n = 10). The cervical vagus nerve was stimulated with bipolar platinum electrodes (20 Hz). Epicardial activation was recorded in sinus rhythm, and effective refractory periods (ERPs), dispersion of refractoriness and conduction times from high-lateral right atrium (RA) to high-lateral left atrium (LA) and PVs assessed at baseline and during vagal stimulation. Burst pacing (50 Hz, 10 s), alone or combined with vagal stimulation, was applied to the right (RAA) and left atrial appendage (LAA) and PVs to induce AF. At baseline, ERPs were lower in PVs than in LA and LAA, but did not differ significantly from RA and RAA, and there was a significant delay in the conduction time from RA to PVs compared with the activation time from RA to LA (P < 0.01). During vagal stimulation, ERP decreased significantly at all sites, without significant differences in the dispersion of refractoriness, and the atrial conduction times changed from 39 ± 19 to 49 ± 9 ms (RA to PVs; n.s.) and from 14 ± 7 to 28 ± 12 ms (RA to LA; P = 0.01). Induction of AF was reproducible in 50% of cases with 50 Hz and in 82% with 50 Hz combined with vagal stimulation (P < 0.05). During vagal stimulation, AF cycle length decreased at all sites, and AF duration changed from 1.0 ± 0.9 to 14.0 ± 10.0 s (P < 0.01), with documentation of PV tachycardia in three cases. In 70% of the animals, AF ceased immediately after interruption of vagal stimulation. We conclude that in the intact rabbit heart, vagal activity prolongs interatrial conduction and shortens atrial and PV ERP, contributing to the vulnerability to the induction and maintenance of AF. This model may be useful in the assessment of the autonomic influence in the mechanisms underlying AF.info:eu-repo/semantics/publishedVersio

On a smoothed penalty-based algorithm for global optimization

This paper presents a coercive smoothed penalty framework for nonsmooth and nonconvex constrained global optimization problems. The properties of the smoothed penalty function are derived. Convergence to an ε -global minimizer is proved. At each iteration k, the framework requires the ε(k) -global minimizer of a subproblem, where ε(k)→ε . We show that the subproblem may be solved by well-known stochastic metaheuristics, as well as by the artificial fish swarm (AFS) algorithm. In the limit, the AFS algorithm convergence to an ε(k) -global minimum of the real-valued smoothed penalty function is guaranteed with probability one, using the limiting behavior of Markov chains. In this context, we show that the transition probability of the Markov chain produced by the AFS algorithm, when generating a population where the best fitness is in the ε(k)-neighborhood of the global minimum, is one when this property holds in the current population, and is strictly bounded from zero when the property does not hold. Preliminary numerical experiments show that the presented penalty algorithm based on the coercive smoothed penalty gives very competitive results when compared with other penalty-based methods.The authors would like to thank two anonymous referees for their valuable comments and suggestions to improve the paper. This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT - Fundac¸ao para a Ci ˜ encia e Tecnologia within the projects UID/CEC/00319/2013 and ˆ UID/MAT/00013/2013.info:eu-repo/semantics/publishedVersio