Measuring Efflux and Permeability in Mycobacteria

Mycobacteria are intrinsically resistant to most antimicrobials, which is generally attributed to the impermeability of their cell wall that considerably limits drug uptake. Moreover, like in other pathogenic bacteria, active efflux systems have been widely characterized from diverse mycobacterial species in laboratory conditions, showing that they can promote resistance by extruding noxious compounds prior to their reaching their intended targets. Therefore, the intracellular concentration of a given compound is determined by the balance between permeability, influx, and efflux. Given the urgent need to discover and develop novel antimycobacterial compounds in order to design effective therapeutic strategies, the contributions to drug resistance made by the controlled permeability of the cell wall and the increased activity of efflux pumps must be determined. In this chapter, we will describe a method that allows (1) the measuring of permeability and the quantification of general efflux activity of mycobacteria, by the study of the transport (influx and efflux) of fluorescent compounds, such as ethidium bromide; and (2) the screening of compounds in search of agents that increase the permeability of the cell wall and efflux inhibitors that could restore the effectiveness of antimicrobials that are subject to efflux

Semen collection and preservation in African catfish, Clarias gariepinus

Stock improvement using quantitative and molecular genetics is an essential part of nowadays production of farm animals and fish. To achieve this in aquaculture, germplasm of both parental sexes should be obtained in a life-saving manner. In captivity, male African catfish, Clariasgariepinus , do not release semen under abdominal massage and have to be sacrificed to obtain sperm from the macerated testes. Of course, this is regarded as a major constrains by the catfish farming sector. Against this background, the research of the present thesis had a two-pronged approach and aimed (a) to induce semen release and facilitate stripping of semen under abdominal massage, and (b) to optimize protocols for cryopreserving semen of the African catfish. To facilitate hand-stripping of semen, several maturational hormones that increase plasma gonadotropin levels and drugs that stimulate contractions of the reproductive tract, such as oxytocin, were tested. The response to some of these treatments was compared between normal males and males that possessed undeveloped seminal vesicles - a possible block of the sperm flow during abdominal massage. Based on the results, it is unlikely that catfish males kept in captivity are not strippable because of a lack of gonadotropin surge. Fertile semen was hand-stripped from males that possessed undeveloped seminal vesicles but not from normal males, suggesting that seminal vesicles actually block the sperm flow during hand-stripping. However, stripping was possible only after treatment with pituitary extract. Oxytocin may play a role in sperm transport in catfish, but more research is needed to optimize dose and latency time. To optimize protocols for semen cryopreservation, different cryoprotectors, cooling rates and temperatures at which plunging into liquid nitrogen occurred, were evaluated. Catfish semen showed good tolerance to freezing and thawing. Hatching rates similar to the fresh semen were obtained with semen frozen in 10% methanol, at a cooling rate of -2, -5 or -10ºC/min to -40ºC and plunged into liquid nitrogen as soon as semen temperature reached -38ºC. Samples plunged into liquid nitrogen from a semen temperature above -30ºC or below -50ºC produced decreasing hatching rates. Post-thaw semen could be diluted at least 200 times without loosing fertilization capacity. Cryopreservation of semen is a valuable tool for selection and conservation of genetic diversity in catfish species.</p

One Anastomosis Gastric Bypass versus Roux en Y Gastric Bypass as Salvage Technique after Failed Gastric Band: a Retrospective Analysis of 80 Cases

The classical “Roux en Y Gastric Bypass” (RYGBP) is still the standard technique between all the ones being used nowadays. The “One anastomosis gastric bypass” (OAGBP), is an evolution of the “Minigastic bypass” described by Robert Rutledge in 2001, is a well known and progressively frequent but still controversial technique. In our group, after an experience of 10 years using the RYGBP as a salvage surgery after failed gastric banding, in 132 cases, we decided to adopt the OAGBP as our preferential bariatric technique also in this situation. The theoretical main reasons for that shift are related to the increased safety, maximized weight loss, long term weight loss maintenance and reversibility of the operation. Method: Retrospectively we evaluated data of the surgical management of revisional cases for conversion, after failed or complicated gastric bands to gastric bypass. We selected the last 40 cases of each technique since May 2010. Results: All cases were performed by laparoscopy without any conversion. In both groups the conversion has been performed in one single step (17 cases, 42,5%). Data showed lower morbidity with OAGBP (2,5% against 7,5%) and better weight loss in theOAGBP cohort after a median follow up of 16months (67%against 55%) in patients revised after gastric band failure or complications. None had statistic significance (p>0,1) by the chi-square contingency table analysis.Conclusion: It seems to there is a difference in favour of OAGBP for conversion of complicated gastric bands. In this study we didn’t found statistic significance probably because of the short numbers. Prospective and more powerful studies are necessary to evaluate the benefit of the studied procedure

Sustainable practices for electrical energy network management: A literature review and proposal

Many different approaches have been proposed for improving energy network management. Although these diverse contributions, most approaches for clearly identifying and accurately solving the real problems remain rather inefficient. This is greatly due to the absence of use of completely integrated and sustainable models with Organizations playing fundamental rolls through the use of effective and efficient decision support tools. One such typical problem is related to the accurate identification and the precise calculation of electrical energy losses, which still remains unsolved as well as the clear specification of the critical points and segments in the networks were problems do occur. Consequently, there is still a lack of effective prioritization of actions and interventions in order to reduce those problems. Therefore, in this paper we propose a model for sustainable energy network management were the organizational element assumes a crucial function.This work was supported by FCT “Fundação para a Ciência e a Tecnologia” under the program: PEst20152020.info:eu-repo/semantics/publishedVersio

Control and Supervision of Wind Energy Conversion Systems

This paper is about a PhD thesis and includes the study and analysis of the performance of an onshore wind energy conversion system. First, mathematical models of a variable speed wind turbine with pitch control are studied, followed by the study of different controller types such as integer-order controllers, fractional-order controllers, fuzzy logic controllers, adaptive controllers and predictive controllers and the study of a supervisor based on finite state machines is also studied. The controllers are included in the lower level of a hierarchical structure composed by two levels whose objective is to control the electric output power around the rated power. The supervisor included at the higher level is based on finite state machines whose objective is to analyze the operational states according to the wind speed. The studied mathematical models are integrated into computer simulations for the wind energy conversion system and the obtained numerical results allow for the performance assessment of the system connected to the electric grid. The wind energy conversion system is composed by a variable speed wind turbine, a mechanical transmission system described by a two mass drive train, a gearbox, a doubly fed induction generator rotor and by a two level converter

The Efficacy of LUCAS in Cardiac Arrest

Introduction: Chest compression is the basic technique of cardiopulmonary resuscitation (CPR) in patients with cardiac arrest. The quality and early performance of CPR is critical to improve the prognosis and chances of restoring spontaneous blood flow. Today we have manual compressions and mechanical chest compression devices. Objective: The aim of this study is to clarify the importance of the LUCAS system (The Lund University Cardiac Arrest System) in CPR. Material and methods: A systematic review of the literature by mobilizing the descriptors "Cardiac Arrest", "Lucas Efficacy" and "nursing", using the methodological head. Ten conceivable databases were selected, between 2010-2020, and seven articles were included for analysis. Results and discussion: The results of the studies are different, as four of the studies indicate that LUCAS is fully effective, particularly in fatigue and transport, but two of them do not recognise its full effectiveness. One of the studies mentions that the fact that compression by the automatic device is effective does not necessarily reflect a better result. The vast majority of the studies recognise the need for further studies to make more convincing decisions. Conclusion: Mechanical chest compression devices can improve patient outcome if used appropriately in the event of cardiac arrest. The hemodynamic performance of the LUCAS compression-decompression system is, according to some results, better than manual CPR. However, the quality of the current evidence is not sufficient. Randomised studies are needed to evaluate the effect of mechanical chest compression devices on survival inside or outsider the hospital.info:eu-repo/semantics/publishedVersio

Efflux Activity Differentially Modulates the Levels of Isoniazid and Rifampicin Resistance among Multidrug Resistant and Monoresistant Mycobacterium tuberculosis Strains

With the growing body of knowledge on the contribution of efflux activity to Mycobacterium tuberculosis drug resistance, increased attention has been given to the use of efflux inhibitors as adjuvants of tuberculosis therapy. Here, we investigated how efflux activity modulates the levels of efflux between monoresistant and multi- and extensively drug resistant (M/XDR) M. tuberculosis clinical isolates. The strains were characterized by antibiotic susceptibility testing in the presence/absence of efflux inhibitors, molecular typing, and genetic analysis of drug-resistance-associated genes. Efflux activity was quantified by real-time fluorometry. The results demonstrated that all the M. tuberculosis clinical strains, susceptible or resistant, presented a faster, rapid, and non-specific efflux-mediated short-term response to drugs. The synergism assays demonstrated that the efflux inhibitors were more effective in reducing the resistance levels in the M/XDR strains than in the monoresistant strains. This indicated that M/XDR strains presented a more prolonged response to drugs mediated by efflux compared to the monoresistant strains, but both maintain it as a long-term stress response. This work shows that efflux activity modulates the levels of drug resistance between monoresistant and M/XDR M. tuberculosis clinical strains, allowing the bacteria to survive in the presence of noxious compounds.publishersversionpublishe

PolyTB: a genomic variation map for Mycobacterium tuberculosis

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) is the second major cause of death from an infectious disease worldwide. Recent advances in DNA sequencing are leading to the ability to generate whole genome information in clinical isolates of M. tuberculosis complex (MTBC). The identification of informative genetic variants such as phylogenetic markers and those associated with drug resistance or virulence will help barcode Mtb in the context of epidemiological, diagnostic and clinical studies. Mtb genomic datasets are increasingly available as raw sequences, which are potentially difficult and computer intensive to process, and compare across studies. Here we have processed the raw sequence data (>1500 isolates, eight studies) to compile a catalogue of SNPs (n = 74,039, 63% non-synonymous, 51.1% in more than one isolate, i.e. non-private), small indels (n = 4810) and larger structural variants (n = 800). We have developed the PolyTB web-based tool (http://pathogenseq.lshtm.ac.uk/polytb) to visualise the resulting variation and important meta-data (e.g. in silico inferred strain-types, location) within geographical map and phylogenetic views. This resource will allow researchers to identify polymorphisms within candidate genes of interest, as well as examine the genomic diversity and distribution of strains. PolyTB source code is freely available to researchers wishing to develop similar tools for their pathogen of interest