Analysis of in vivo absorption of didanosine tablets in male adult dogs by HPLC

AbstractDidanosine is an effective antiviral drug in untreated and antiretroviral therapy-experienced patients with Human Immunodeficiency Virus (HIV). An automated system using on-line solid extraction and High Performance Liquid Chromatography (HPLC) with ultraviolet (UV) detection was developed and validated for pharmacokinetic analysis of didanosine in dog plasma. Modifications were introduced on a previous methodology for simultaneous analysis of antiretroviral drugs in human plasma. Extraction was carried out on C18 cartridges, with high extraction yield as stationary phase, whereas mobile phase consisted of a mixture of 0.02 M potassium phosphate buffer, acetonitrile (KH2PO4: acetonitrile: 96:4, v/v) and 0.5% (w/v) of heptane sulphonic acid. The pH was adjusted to 6.5 with triethylamine. All samples and standard solutions were chromatographed at 28°C. For an isocratic run, the flux was 1.0mL/min, detection was at 250nm and injected volume was 20μL. The method was selective and linear for concentrations between 50 and 5000ng/mL. Drug stability data ranged from 96% to 98%, and limit of quantification was 25ng/mL. Extraction yield was up to 95%. Drug stability in dog plasma was kept frozen at −20°C for one month after three freeze–thaw cycles, and for 24h after processing in the auto sampler. Assay was successfully applied to measure didanosine concentrations in plasma dogs

Efecto de la introducción de peces en la conservación de anfibios y crustáceos de lagos de alta montaña

Este capítulo contiene 16 páginas, 11 figuras y una tabla.La introducción de especies invasoras es un aspecto determinante relacionado con el cambio global que incide en la conservación de los ecosistemas. Actualmente, la gestión para la conservación (e.g., Parques Nacionales) se enfrenta a las incertidumbres creadas con la aparición de nuevas especies introducidas por el hombre, sobre todo las que pasan a desarrollar un papel clave en los ecosistemas. Para poder tomar políticas de gestión correctas es necesario conocer con detalle cuál es el impacto de estas especies y su papel en el ecosistema. Los lagos del Parque Nacional de Aigüestortes y Estany de Sant Maurici han sufrido la introducción de peces llegando a tener en la actualidad un 62% de lagos afectados. El objetivo general del proyecto fue estudiar el efecto de la introducción de peces en las comunidades planctónicas y bentónicas de los lagos de alta montaña del Parque Nacional. Para llevar a cabo tal objetivo nos centramos en el estudio de dos grupos de organismos indicadores, los crustáceos del plancton y los anfibios. Los resultados obtenidos nos muestran que los peces son el factor principal que explica la presencia de la mayor parte de las especies de anfibios en los lagos. En cambio el efecto de los peces sobre la presencia de crustáceos planctónicos se limita a las especies de mayor tamaño, afectando principalmente la biodiversidad y especialmente la abundancia de los crustáceos, que disminuye con la presencia de peces. La desaparición de los anfibios en los lagos con peces provoca un efecto en cascada cambiando biomasa y composición de las algas y procariotas (bacterias y arqueas) que viven en la superfície de las piedras del litoral de los lagos.Peer reviewe

Assessment of the genotoxic potential of contaminated estuarine sediments in fish peripheral blood: laboratory versus in situ studies

Juvenile Senegalese soles (Solea senegalensis) were exposed to estuarine sediments through 28-day laboratory and in situ (field) bioassays. The sediments, collected from three distinct sites (a reference plus two contaminated) of the Sado Estuary (W Portugal) were characterized for total organic matter, redox potential, fine fraction and for the levels of metals, polycyclic aromatic hydrocarbons (PAHs) and organochlorines, namely polychlorinated biphenyls (PCBs) and dichloro diphenyl tricholoethane plus its main metabolites (DDTs). Genotoxicity was determined in whole peripheral blood by the single-cell gel electrophoresis (SCGE or ‘‘comet’’) assay and by scoring erythrocytic nuclear abnormalities (ENA). Analysis was complemented with the determination of lipid peroxidation in blood plasma by the thiobarbituric acid reactive substances (TBARS) protocol and cell type sorting. The results showed that exposure to contaminated sediments induced DNA fragmentation and clastogenesis. Still, laboratory exposure to the most contaminated sediment revealed a possible antagonistic effect between metallic and organic contaminants that might have been enhanced by increased bioavailability. The laboratory assay caused a more pronounced increase in ENA whereas a very significant increase in DNA fragmentation was observed in field-tested fish exposed to the reference sediment, which is likely linked to increased lipid peroxidation that probably occurred due to impaired access to food. Influence of natural pathogens was ruled out by unaltered leukocyte counts. The statistical integration of data correlated lipid peroxidation with biological variables such as fish length and weight, whereas the genotoxicity biomarkers were more correlated to sediment contamination. It was demonstrated that laboratory and field bioassays for the risk assessment of sediment contamination may yield different genotoxicity profiles although both provided results that are in overall accordance with sediment contamination levels. While field assays may provide more ecologically relevant data, the multiple environmental variables may produce sufficient background noise to mask the true effects of contamination.info:eu-repo/semantics/publishedVersio

A new approach for routine quantification of microplastics using Nile Red and automated software (MP-VAT)

Microplastics are widespread contaminants in the environment. However, most identification protocols rely on long and subjective visual counting, which could be improved using staining dyes. Thus, the objective of this work is to identify the best staining dye protocol and create an objective and quick automated counting software for microplastics. Tests were conducted to identify the most appropriate of eight staining dye solutions and of six wavelengths for virgin and weathered synthetic polymers, textile fibers, natural organic matter and filters. Nile Red produced the best results (without interfering in infrared spectra) rendering microplastics fluorescent at 254 nm, but with limited number of fluorescent polymers, and at 470 nm (with orange filter), with fluorescence of plastics as well as natural organic matter (requiring a digestion step). Next, a script was developed in ImageJ for the automatic quantification and characterization in shape (fiber, fragment, particle) and size of fluorescent microplastics, the Microplastics Visual Analysis Tool (MP-VAT). MP-VAT was evaluated, producing recovery rates in the range of 89.0-111.1% in spiked filters under 470 nm. Furthermore, this package is accompanied by a script that sets a scale from a known filter diameter, MP-SCALE, and a script that allows user threshold setting, MP-ACT.publishe

Multiobjective approach to optimal control for a dengue transmission model

During the last decades, the global prevalence of dengue progressed dramatically. It is a disease which is now endemic in more than one hundred countries of Africa, America, Asia and the Western Pacific. This study addresses a mathematical model for the dengue disease transmission and finding the most effective ways of controlling the disease. The model is described by a system of ordinary differential equations representing human and vector dynamics. Multiobjective optimization is applied to find the optimal control strategies, considering the simultaneous minimization of infected humans and costs due to insecticide application. The obtained results show that multiobjective optimization is an effective tool for finding the optimal control. The set of trade-off solutions encompasses a whole range of optimal scenarios, providing valuable information about the dynamics of infection transmissions. The results are discussed for different values of model parameters.FCOMP-01-0124-FEDER-02889

Determination of paralytic shellfish toxins using potentiometric electronic tongue

Paralytic shellfish toxins (PSTs) are monitored in commercial bivalves in several countries in the world due to their toxicity to human consumers. The present work examines the application of an electronic tongue based on potentiometric chemical sensors to the quantification of PSTs in mussel extracts. The electronic tongue comprised six miniaturized sensors with solid inner contact and plasticized polyvinylchloride membranes. Calibration models were calculated by PLS regression using measurements in sixteen model mixed solutions containing four PSTs commonly found in bivalves from the Portuguese coast. Transfer of the calibration models to sample matrix was done by joint-PLS regression using measurements in five mussel extracts spiked with PST standards. Quantification of PSTs in extracts of naturally contaminated mussels, using the electronic tongue and updated calibration model, was in agreement with values of the chromatographic reference method. Those sensors alone or combined in an electronic tongue are useful tools for rapid screening of PST in bivalves.publishe

First report of canine ocular thelaziosis by Thelazia callipaeda in Portugal

BACKGROUND: Thelazia callipaeda eyeworms are transmitted by the non-biting insect vector Phortica variegata in Europe and infest the conjunctiva(s) of several mammalians, including dogs and humans. Infested hosts might remain asymptomatic or display clinical manifestations characterized by variable degrees of severity. METHODS: From July to November 2011, nine dogs were detected with eyeworms at two veterinary clinics in Chaves and Bragança (North of Portugal). Nematodes collected from dogs were morphologically and molecularly characterized at species level. RESULTS: Nematodes were identified as T. callipaeda. The number of worms collected from each dog ranged from three to 76 (average = 17.9 ± 26.8) and was not associated with the severity of clinical signs. Ocular discharge and conjunctivitis were observed in all dogs and ocular pruritus occurred in six of them. Polymerase chain reaction and sequencing of a portion of target cytochrome c oxidase subunit 1 gene further identified all nematodes as haplotype 1. CONCLUSIONS: This is the first report of T. callipaeda and associated ocular disease in dogs from Portugal, suggesting that thelaziosis should be included in the differential diagnosis of canine ocular affections. The risk of the infestation spreading from Spain and France to Portugal, through domestic dogs or wild mammals, is realistic

The nucleic acid-binding protein PcCNBP is transcriptionally regulated during the immune response in red swamp crayfish Procambarus clarkii

Gene family encoding cellular nucleic acid binding proteins (CNBP) is well conserved among vertebrates; however, there is limited knowledge in lower organisms. In this study, a CNBP homolog from the red swamp crayfish Procambarus clarkii was characterised. The full-length cDNA of PcCNBP was of 1257 bp with a 5′-untranslated region (UTR) of 63 bp and a 3′-UTR of 331 bp with a poly (A) tail, and an open-reading frame (ORF) of 864 bp encoding a polypeptide of 287 amino acids with the predicted molecular weight of about 33 kDa. The predicted protein possesses 7 tandem repeats of 14 amino acids containing the CCHC zinc finger consensus sequence, two RGG-rich single-stranded RNA-binding domain and a nuclear localization signal, strongly suggesting that PcCNBP was a homolog of vertebrate CNBP. The PcCNBP transcript was constitutively expressed in all tested tissues of unchallenged crayfish, including hepatopancreas, gill, eyestalk, haemocytes, intestine, stomach and cuticle with highest expression in haemocytes, intestine, gills and hepatopancreas. The mRNA expression of PcCNBP in haemocytes was modulated at transcriptional level by different immune challenges, suggesting its involvement in the immune response of P. clarkii during both bacteria and viruses infection

El profesor de música como actor de cambio social en proyectos de Estados Unidos, Ecuador, Bolivia y Argentina inspirados en el sistema de orquestas infantiles y juveniles de Venezuela : una aproximación al paradigma relacional de Pierpaolo Donati y el marco morfogenético para el realismo social de Margaret Archer

La presente investigación propone situar al profesor de música como actor de cambio social en contextos de desarrollo en Argentina, Bolivia, Estados Unidos y Ecuador, a través de programas inspirados en El Sistema de Orquestas Infantiles y Juveniles de Venezuela. A partir del paradigma relacional de Pierpaolo Donati y el marco morfogenético para el realismo social de Margaret Archer se busca conocer las experiencias de profesores de música para establecer cómo la relación es la base de los cambios sociales generados en los distintos contextos; argumentando que los bienes relacionales que producen son consecuencia única y directa de la interacción entre sujetos relacionales individuales y colectivos