Fongs oportunistes: Avaluació de la patogènia i sensibilitat als antifungics

Les infeccions greus causades per fongs han augmentat molt en els últims anys, i sobretot les causades pels anomenats fongs oportunistes. Aquests últims acostumen a provocar infeccions en pacients que tenen altres malalties de base, com per exemple leucèmia, SIDA, càncer, o han rebut trasplantaments d'òrgans sòlids o de moll d'os. La llista de les espècies de fongs oportunistes implicades en infeccions greus és cada dia més llarga, i les estratègies per tractar aquestes infeccions continuen essent molt limitades. Els tres gèneres de fongs filamentosos oportunistes que han estat objecte d'estudi a la present tesi, Fusarium, Scedosporium i Paecilomyces es troben dins d'aquest grup de fongs oportunistes. Encara que només provoquen infeccions greus en pacients immunocompromesos, la taxa de mortalitat d'aquestes infeccions s'acosta al 100%. L'amfotericina B ha estat durant molts anys, i encara ho és en l'actualitat, el fàrmac més utilitzat per tractar les infeccions sistèmiques, però té importants problemes de toxicitat. En els últims anys s'han desenvolupat altres formulacions d'aquest mateix fàrmac, que presenten molts menys problemes de toxicitat. L'objectiu principal d'aquesta tesi ha estat avaluar l'eficàcia d'una de les noves formulacions de l'amfotericina B, el preparat liposòmic, en models animals d'infecció disseminada.Per poder comparar els diferents tractaments primer ha calgut desenvolupar models animals d'infecció per cadascun dels fongs estudiats (utilitzant ratolins), que siguin reproduïbles i que puguin simular la infecció fúngica humana.Un cop desenvolupats els models animals es va comparar l'eficàcia de les dues formulacions de l'amfotericina B, en el tractament de les infeccions causades pels fongs estudiats. Això s'avaluava comparant amb mètodes estadístics el temps de supervivència (TMS) dels diferents grups. També es comparava la quantitat de fong present a diferents òrgans dels ratolins, que eren sacrificats quan finalitzava el tractament. A part de l'amfotericina B que és, tal i com hem dit, el fàrmac més utilitzat per combatre les infeccions provocades per fongs oportunistes, hi ha d'altres antifúngics, però han demostrat poca eficàcia al menys in vitro, i els resultats clínics són molt escassos. És per això que hem volgut avaluar el possible efecte sinèrgic d'algunes combinacions d'antifúngics in vitro.De forma resumida, les conclusions principals que es desprenen dels diversos estudis realitzats són els següents.1- Es van establir models d'infecció disseminada en ratolins per les espècies següents Paecilomyces variotii, P. lilacinus, P. javanicus, Fusarium verticillioides, Scedosporium prolificans, S. apiospermum en ratolins immunodeprimits o immunocompetents.2- Es va avaluar l'eficàcia de les dues formulacions de l'antifúngic amfotericina B (el desoxicolat i la formulació liposòmica) en diferents models d'infecció experimental desenvolupats en la primara fase dels estudis.En ratolins infectats amb P. variotii, les dues formulacions van ser equivalents a dosis baixes, però l'administració d'amfotericina B liposòmica a 10 mg/kg va provocar una disminució significativa de la presència del fong en alguns òrgans.Les dosis baixes d'amfotericina B liposòmica va fer augmentar el TMS dels ratolins infectats amb F. verticillioides. Les dosis altes, a més, van fer disminuir significativament la presència del fong en diversos òrgans.En els ratolins infectats per S. prolificans, es va observar un increment del TMS, que va ser més evident amb la dosi més alta d'amfotericina B liposòmica. L'administració de G-CSF amb la teràpia antifúngica no va millorar els resultats. 3- S'ha avaluat l'activitat in vitro de nou combinacions d'antifúngics davant de diverses espècies dels gèneres Fusarium i Paecilomyces.Les combinacions que s'han comportat de forma sinèrgica per un nombre més elevat de soques han estat les de ravuconazol combinat tant amb amfotericina B com amb terbinafina, i aquesta última combinada amb voriconazol. Les combinacions que s'han comportat de forma sinèrgica per un nombre més elevat de soques han estat totes les de terbinafina combinada amb azols.Deep infections caused by moulds have increased during the last years, and especially those caused by opportunistic fungi. These fungi use to provoke infections in patients with underlying diseases such as leukaemia, AIDS, cancer, and solid organ or bone marrow transplant recipients. The number of fungal species involved in deep infections increases every day, and the strategies to treat these infections are still limited. The three genera of filamentous fungi that have been studied in the present thesis Fusarium, Scedosporium and Paecilomyces are included in the group of emerging opportunistic pathogens. Even though they just provoke severe infections in immunocompromised patients, the mortality rate is close to 100%. Amphotericin B has been for many years, and is still nowadays, the most used drug to treat the systemic infections, but it has important toxicity problems. In recent years newer formulations of the drug have been developed, which show less toxicity problems. The main objective of the present thesis has been to evaluate the efficacy of one of the newer formulations of amphotericin B, the liposomal preparation, in murine models of disseminated infection.To be able to compare both treatments we previously developed reproducible animal models of infection (using mice) that could simulate the human infection, for each one of the strains. This was in order to compare the efficacy of both formulations of amphotericin B, in the treatment of the infections caused by the studied fungi. This was evaluated by comparing using statistic methods the mean survival time of the different groups of mice (MST). We also compared the tissue burden of the fungi in several target organs of mice, which were sacrificed after the treatment. In addition to amphotericin B which is, as we said before, the most widely used drug to treat infections caused by opportunistic fungi, there are other antifungal agents, but they have shown low efficacy, at least in vitro, and the clinical results are very scarce. That is why we wanted to evaluate the possible synergic effect in vitro of some of these drug combinations.In a resumed way, the main conclusions derived from the several performed studies are as follows:1- We established murine models of disseminaded infection by the following species: Paecilomyces variotii, P. lilacinus, P. javanicus, Fusarium verticillioides, Scedosporium prolificans, and S. apiospermum in immunosuppressed or immunocompetent mice.2- We evaluated the efficacy of two formulations of the antifungal agent amphotericin B (the deoxycholate and the liposomal formulations) in the different experimental infection models developed in the first phase of the studies.In mice infected with P. variotii, both formulations showed similar results at low doses, but the administration of liposomal amphotericin B at 10 mg/kg provoked a significant decrease of the presence of the fungus in target organs.Low doses of liposomal amphotericin B increased the MST of mice infected with F. verticillioides. At high doses, it also lowered the presence of the fungus in several organs.In mice infected with S. prolificans, the administration of high doses of high doses of liposomal amphotericin B provoked an increase of MST, which was more evident with the highest dose. The administration of G-CSF together with the antifungal therapy did not improve the results. 3- We evaluated the in vitro activity of nine combinations of antifungal drugs against several species of the genera Fusarium and Paecilomyces.The combinations that showed a highest percentage of synergic effects for Fusarium were ravuconazole combined with amphotericin B or terbinafine, and terbinafine with voriconazole. The combinations that showed a highest percentage of synergic effects for Paecilomyces were terbinafine combined with any of the azoles

Controlling Water Temperature during the Electrocoagulation Process Using an Innovative Flow Column-Electrocoagulation Reactor

A flow column has been innovatively used in the design of a new electrocoagulation reactor (ECR1) that will reduce the temperature of water being treated; where the flow columns work as a radiator for the water being treated. In order to investigate the performance of ECR1 and compare it to that of traditional reactors; 600 mL water samples with an initial temperature of 350C were pumped continuously through these reactors for 30 min at current density of 1 mA/cm2. The temperature of water being treated was measured at 5 minutes intervals over a 30 minutes period using a thermometer. Additional experiments were commenced to investigate the effects of initial temperature (15-350C), water conductivity (0.15 – 1.2 mS/cm) and current density (0.5 -3 mA/cm2) on the performance of ECR1. The results obtained demonstrated that the ECR1, at a current density of 1 mA/cm2 and continuous flow model, reduced water temperature from 350C to the vicinity of 280C during the first 15 minutes and kept the same level till the end of the treatment time. While, the temperature increased from 28.1 to 29.80C and from 29.8 to 31.90C in the batch and the traditional continuous flow models respectively. In term of initial temperature, ECR1 maintained the temperature of water being treated within the range of 22 to 280C without the need for external cooling system even when the initial temperatures varied over a wide range (15 to 350C). The influent water conductivity was found to be a significant variable that affect the temperature. The desirable value of water conductivity is 0.6 mS/cm. However, it was found that the water temperature increased rapidly with a higher current density

Experimental characterisation of non-encapsulated bio-based concrete with self-healing capacity

The main reason for early corrosion in Reinforced Concrete (RC) structures is crack formation within the concrete cover. Cracks can lead to leakage problems, allowing chloride, oxygen, water and other aggressive chemicals to enter into concrete and eventually causes corrosion of steel reinforcement. The paper shows some results of a novel bio concrete with biological self-healing agent, which added into the concrete mixture, autonomously and actively, inhibits the concrete cracks and potential premature reinforcement corrosion. Two compositions of concrete samples were prepared and casted – CEMI and CEMIII with 60% of Ground Granulated Blast Furnace Slag (GGBS) with and without non-encapsulated bio-product utilising iron respiring bacteria. The developed bio-mineral is capable of sealing cracks and blocking pores resulting in a delay of waterborn ions in RC structures, acting as a diffusion barrier of oxygen to protect steel reinforcement's passivity towards corrosion. The fresh test results show that these concretes have the potential to be used in RC heavily reinforced and manually compacted sections with vibrations. The water absorption velocity has been significantly reduced with the inclusion of bio-agent in CEMI and CEMIII concretes samples, which was associated with pores sealing. Maximum water absorption via capillary tends to reduce at least 25% when bio-agent was introduced to concrete type CEMIII. Other results emphases the efficiency of the bio-product in CEMIII medium. The bio-agent does not decrease the compressive strength of tested concretes either for CEMI and CEM III. SEM observation shows that the crystals were well developed near the surface of the crack

Improving biodiesel yield of animal waste fats by combination of a pre-treatment technique and microwave technology Renewable Energy

Recently, due to its low cost there has been increased attention on Animal Waste Fats (AWFs) as a feedstock for biodiesel production. Advanced microwave technology has also been reported by many researchers to enhance the transesterification in biodiesel production. However, esterification of free fatty acids in the feedstock reported here has not attracted so much attention. AWFs come with its challenges namely, high free fatty acid (FFA) content and high water content. This study utilizes AWFs (tallow) containing very large amount of FFA; (25wt.%, 18 wt.%, and 9.4 wt.% FFA/AWFs) as feedstock for fatty acid methyl ester (FAME) production. A simple thermal pre-treatment technique followed microwave assisted esterification with methanol (MeOH) was conducted in a batch process to reduce the FFA content to as low as 1wt.% FFA, which is then suitable for the alkaline transesterification process. The pre-treatment of AWFs at 88°C to first reduce water and decrease viscosity, followed by an operating microwave power of 70W producing a power density 1.147mW/m3, achieved a 15% increase in reduction of FFA over 30W microwave power and conventional thermal method. Under optimum conditions, using 2.0 wt.wt% sulphuric acid catalyst/AWFs and 1:6 molar ratio AWF/MeOH, the FFA conversion of 93wt. % was achieved. The results indicated that the pre-treatment and microwave application provided a faster route to high FFA reduction of AWFs during esterification process. The proposed technology is promising for the potential scale up industrial application

Influence of electrodes spacing on internal temperature of electrocoagulation (EC) cells during the removal (Fe II) from drinking water

The electrocoagulation (EC) method, which is in situ generation of coagulating ions by applying direct electrical current to metallic electrodes, has recently been applied to remove a wide spectrum of pollutants from waters and wastewaters. However, its efficiency is highly influenced by key operational parameters such as electrolysis time and current density. Therefore, the current investigation has been carried out to explore the influence of electrodes spacing on the performance of EC method in terms of internal temperature iron removal from drinking water. To achieve the planned target, iron containing synthetic water samples were electrolysed, for 25 min, using a flow column electrocoagulation reactor (FCER), at three different distances between electrodes (5, 10, and 20 mm). The progression of temperature of water being treated was measured at 5 minutes intervals over a 25 minutes period. These batch experiments were commenced at a constant current density of 1.5 mA/cm2 and initial pH of 6. The results obtained showed that the amount of produced heat is directly proportional to the DBE, where it has been noticed that the water temperature increased by about 9% as the distance between electrodes increased from 5 to 20 mm, respectively

Identification of Optimal Frequencies to Determine Alpha-Cypermethrin using Machine Learning Feature Selection Techniques

Machine learning feature space reduction techniques allow for vast feature spaces to be reduced with little loss or even significant improvements in the reliability of predictions of models. Microwave spectroscopy with feature spaces of over 8000 are not uncommon when considering magnitude and phase. Applying Machine learning techniques to this type of feature space allows for a quicker reduction and helps to identify the most suitable predictive features. The control of insect vectors that transmit diseases including malaria, visceral leishmaniasis and zika rely on the use of insecticide. These diseases affect millions, malaria alone accounted for 214 million new cases resulting in 438, 000 deaths in 2015. One method used in controlling the vectors is through indoor residual spraying, applying insecticide to the wall surface inside houses. Alpha-cypermethrin is one of the insecticides that is currently sprayed in several countries for vector control. Quality assurance and monitoring of the control activities is challenging relying on the use of laboratory-reared insects. This was improved with a chemical based Insecticide Quantification Kit, but these assays have been challenging to operationalise. An electromagnetic sensor is being developed to investigate the potential to detect alpha-cypermethrin. Preliminary experiments were carried out to differentiate tiles sprayed with Technical Grade alpha-cypermethrin, wettable powder containing 5% alpha-cypermethrin and wettable powder with over dose of alpha-cypermethrin using a horn antenna at a frequency range between 1 GHz to 6 GHz. The experimental results indicated the potential use of electromagnetic waves to determine alpha-cypermethrin in a non-destructive manner

Removal of phosphate from River water using a new baffle plates electrochemical reactor

During the last 50 years, the human activities have significantly altered the natural cycle of phosphate in this planet, causing phosphate to accumulate in the freshwater ecosystems of some countries to at least 75% greater than preindustrial levels, which indicates an urgent need to develop efficient phosphate treatment methods. Therefore, the current study investigates the removal of phosphate from river water using a new electrochemical cell (PBPR). This new cell utilises perforated baffle plates as a water mixer rather than magnetic stirrers that require power to work. This study investigates the influence of key operational parameters such as initial pH (ipH), current density (Ј), inter-electrode distance (ID), detention time (t) and initial phosphate concentration (IC) on the removal efficiency, and influence of the electrocoagulation process on the morphology of the surface of electrodes. Overall, the results showed that the new reactor was efficient enough to reduce the concentration of phosphate to the permissible limits. Additionally, SEM images showed that the Al anode became rough and nonuniform due to the production of aluminium hydroxides. The main advantages of the electrocoagulation technique are: 1- The EC method does not produce secondary pollutants as it does not required chemical additives, while other traditional treatment methods required either chemical or biological additives [[1], [2], [3], [4]]. 2- It has a large treatment capacity and a relatively short treatment time in comparison with other treatment methods, such as the biological methods [1,[5], [6], [7]]. 3- The EC method produces less sludge than traditional treatment traditional chemical and biological treatment methods [8,9]. EC technology, like any other treatment method, has some drawbacks that could limit its performance. For instance, it still has a clear deficiency in the variety of reactor design, and the electrodes should be periodically replaced as they dissolve into the solution due to the oxidation process [2,10]

Electrocoagulation as a green technology for phosphate removal from River water

The current study investigates the removal of phosphate from water using a new baffle plates aluminium-based electrochemical cell (PBPR) taking consideration the influence of key operating parameters. This new cell utilises perforated baffle plates as a water mixer rather than magnetic stirrers that require extra power to work. As this unit is new, a comprehensive study has been carried to assess it performance. This study also includes preliminary estimates of the reactor’s operating costs, the amount of H2 gas produced and the yieldable energy from it. SEM (scanning electron microscope) was used to investigate the influence of the electrocoagulation process on the morphology of the surface of aluminium electrodes, and an empirical model developed to reproduce the phosphate removal process. The results showed that 99% of phosphate was removed within 60 minutes of electrolysis at an initial pH (ipH) of 6, inter-electrode distance (ID) of 0.5 cm, current density (J) of 6 mA/cm2, initial concentration of phosphate (IC) of 100 mg/L, and minimum operating cost of 0.503 US $/m3. The electrochemical cell produced enough H2 gas to generate 4.34 kWh/m3 of power. Statistically, it was proved that the influence of the operating parameters on phosphate removal could be modelled with an R2 of 0.882, the influence of these operating parameters on phosphate removal following the order: t>J>IC>ipH >ID. Finally, SEM images showed that after several electrolysing runs, the Al anode became rough and nonuniform which could be related to the production of aluminium hydroxides