Caracterização molecular da mutação pso8-1/rad6 de Saccharomyces cerevisiae, sensível à fotoadição de psoralenos, à radiação UVC e a mutágenos químicos

Um novo mutante isolado da levedura Saccharomyces cerevisiae, sensível à fotoativação de psoralenos mono- e bi-funcionais, à UVC e ao MNNG, complementou o fenótipo de sensibilidade à fotoadição de psoralenos conferido pelas mutações pso1 a pso7 e assim foi chamado pso8-1. O duplo mutante pso8-1 rad4-4 foi altamente sensível à UVC, indicando assim uma interação sinergística dos dois mutantes alelos. A clonagem molecular pela complementação do fenótipo de sensibilidade à radiação UVC do mutante pso8-1 e estudos genéticos revelaram que pso8-1 é alelo ao gene RAD6. O produto do gene RAD6/UBC2 é uma enzima conjugada à ubiquitina envolvida em reparação de DNA, esporulação, recombinação, indução de mutagênese, degradação de proteínas, genes silenciosos, transposição Ty1. Enquanto o mutante pso8-1 apresenta um fenótipo mutador espontâneo e possui baixa mutabilidade induzida a mutágenos, a esporulação de diplóides homoalélicas mostrou eficiência próxima à da linhagem selvagem. A análise da seqüência do mutante alelo mostrou que pso8-1 contém uma nova, e até agora desconhecida, transição T→C no nucleotídeo 191, levando à substituição de uma prolina altamente conservada por uma leucina na posição 64 (Rad6-[P64L]) que pode ter severas conseqüências na estrutura terciária da proteína mutada, e conseqüente ligação a pRad18.

Análise proteômica de Chromobacterium violaceum: acúmulo estacionário e diferencial após exposição à luz UVC

Chromobacterium violaceum is a free-living bacillus, Gram-negative commonly found in water and sand of tropical and subtropical regions. One of its main characteristic it's the ability to produce the purple pigment named violacein, that shows countless biological activities. In 2003, the genome of this organism was totally sequenced and revealed important informations about the physiology of this bacteria. However, few post-genomics studies had been accomplished. This work evaluated the protein profile of C. violaceum cultivated in LB medium at 28ºC that allowed the identification and characterization of proteins related to a possible secretion system that wasn't identified and characterized yet in C. violaceum, to the quorum sensing system, to regulatory process of transcription and translation, stress adaptation and biotechnological potential. Moreover, the response of the bacteria to UVC radiation was evaluated. The comparison of the protein profile, analyzed through 2-D electrophoresis, of the control group versus the treatment group allowed the identification of 52 proteins that arose after stress induction. The obtained results enable the elaboration of a stress response pathway in C. violaceum generated by the UVC light. This pathway, that seems to be a general stress response, involves the expression of proteins related to cellular division, purine and pirimidine metabolism, heat chock or chaperones, energy supply, regulation of biofilm formation, transport, regulation of lytic cycle of bacteriophages, besides proteins that show undefined function. Despite the response present similarities with the classic SOS response of E. coli, we still cannot assert that C. violaceum shows a SOS-like response, mainly due to the absence of characterization of a LexA-like protein in this organism

UVC emitting phosphors obtained by spray pyrolysis

The broadband inter-configurational (4f(1)5d(1)-->4f(2)) emission of Pr(3+) doped in lanthanum orthophosphate (LaPO(4)) and in calcium pyrophosphate (Ca(2)P(2)O(7)) has been investigated under plasma excitation. The synthesis by spray pyrolysis at moderate temperature followed by a controlled annealing proves to be a very efficient way to produce good quality UVC emitting phosphor Ca(1.92)Pr(0.04)Na(0.04)P(2)O(7) (alpha phase). The emission of this phosphor in the wavelength range 200-350 nm has been measured with a prototype device, which can be employed for anti-microbial testing. (C) 2010 Elsevier B.V. All rights reserved.

Análise proteômica de Chromobacterium violaceum: acúmulo estacionário e diferencial após exposição à luz UVC

Chromobacterium violaceum is a free-living bacillus, Gram-negative commonly found in water and sand of tropical and subtropical regions. One of its main characteristic it's the ability to produce the purple pigment named violacein, that shows countless biological activities. In 2003, the genome of this organism was totally sequenced and revealed important informations about the physiology of this bacteria. However, few post-genomics studies had been accomplished. This work evaluated the protein profile of C. violaceum cultivated in LB medium at 28ºC that allowed the identification and characterization of proteins related to a possible secretion system that wasn't identified and characterized yet in C. violaceum, to the quorum sensing system, to regulatory process of transcription and translation, stress adaptation and biotechnological potential. Moreover, the response of the bacteria to UVC radiation was evaluated. The comparison of the protein profile, analyzed through 2-D electrophoresis, of the control group versus the treatment group allowed the identification of 52 proteins that arose after stress induction. The obtained results enable the elaboration of a stress response pathway in C. violaceum generated by the UVC light. This pathway, that seems to be a general stress response, involves the expression of proteins related to cellular division, purine and pirimidine metabolism, heat chock or chaperones, energy supply, regulation of biofilm formation, transport, regulation of lytic cycle of bacteriophages, besides proteins that show undefined function. Despite the response present similarities with the classic SOS response of E. coli, we still cannot assert that C. violaceum shows a SOS-like response, mainly due to the absence of characterization of a LexA-like protein in this organism

Treatment of Aqueous Effluents Containing Phenol by the O(3), O(3)-UV, and O(3)-H(2)O(2) Processes: Experimental Study and Neural Network Modeling

In this work, the oxidation of the model pollutant phenol has been studied by means of the O(3), O(3)-UV, and O(3)-H(2)O(2) processes. Experiments were carried out in a fed-batch system to investigate the effects of initial dissolved organic carbon concentration, initial, ozone concentration in the gas phase, the presence or absence of UVC radiation, and initial hydrogen peroxide concentration. Experimental results were used in the modeling of the degradation processes by neural networks in order to simulate DOC-time profiles and evaluate the relative importance of process variables.

Variability in UVB Tolerances of Melanized and Nonmelanized Cells of Cryptococcus neoformans and C-laurentii

Solar radiation is one of the major factors responsible for the control of fungus populations in the environment. Inactivation by UVA and UVB radiation is especially important for the control of fungi that disperse infective units through the air, including fungi such as Cryptococcus spp. that infect their vertebrate hosts by inhalation. Cryptococcus neoformans produces melanin in the presence of certain exogenous substrates such as l-3,4 dihydroxyphenylalanine and melanization may protect the fungus against biotic and abiotic environmental factors. In the present study, we investigated the effect of exposure to an UVB irradiance of 1000 mW m(-2) (biologically effective weighted irradiance) on the survival of melanized and nonmelanized cells of four strains of C. neoformans and four strains of C. laurentii. The relative survival (survival of cells exposed to radiation in relation to cells not exposed) of cells grown 2, 4, 6 or 8 days on medium with or without L-dopa was determined after exposure to UVB doses of 1.8 and 3.6 kJ m(-2). Both the irradiance spectrum and the intensities of those doses are environmentally realistic, and, in fact, occur routinely during summer months in temperate regions. Differences in tolerance to UVB radiation were observed between the C. neoformans and C. laurentii strains. The C. neoformans strains were more susceptible to UVB radiation than the C. laurentii strains. In C. neoformans, differences in tolerance to radiation were observed during development of both melanized and nonmelanized cells. For most treatments (strain, time of growth and UVB dose), there were virtually no differences in tolerances between melanized and nonmelanized cells, but when differences occurred they were smaller than those previously observed with UVC. In tests with two strains of C. laurentii, there was no difference in tolerance to UVB radiation between melanized and nonmelanized cells during 8 days of culture; and in tests with four strains for less culture time (4 days) there were no significant differences in tolerance between melanized and nonmelanized cells of any strain of this species.

Photosensitization of the sunscreen octyl p-dimethylaminobenzoate by UVA in human melanocytes but not in keratinocytes

Sunscreens penetrate human epidermis and modify the biology of proliferating cells. This study addressed the question whether the UV response of cultured human cells is affected by direct treatment with nontoxic levels of sunscreens. Cell survival following exposure to UVC or unfiltered UVB was not altered by preincubation with 25 μg/mL of octyl p-dimethylaminobenzoate (o-PABA), 2-ethylhexyl p-methoxycinnamate (EHMC) or oxybenzone. However, UVA or UVB filtered to reproduce the solar UV spectrum penetrating to the basal layer of the epidermis, highly sensitized cells to killing by o-PABA but not by its hydrolysis product, 4-dimethylaminobenzoic acid. Sensitization was found in all cell types tested, except normal keratinocytes, and could be prevented by certain antioxidants particularly pyruvate and the hydroxyl radical scavenger mannitol. o-PABA and EHMC applied without UV reduced the adherence of cells. The results indicate that sunscreens may increase cell mobility and the combination of o-PABA with solar UV may selectively damage melanocytes in the skin.

Planeamento espacial marinho das áreas marinhas protegidas: o caso de estudo da ára protegida de gestão de recursos: Caloura - ilhéu de Vila Franca do Campo

Tese de Doutoramento, Ciências do Mar (Ecologia Marinha), 26 de Novembro de 2013, Universidade dos Açores.

The clinical and biological impact of new pathogen inactivation technologies on platelet concentrates.

Since 1990, several techniques have been developed to photochemically inactivate pathogens in platelet concentrates, potentially leading to safer transfusion therapy. The three most common methods are amotosalen/UVA (INTERCEPT Blood System), riboflavin/UVA-UVB (MIRASOL PRT), and UVC (Theraflex-UV). We review the biology of pathogen inactivation methods, present their efficacy in reducing pathogens, discuss their impact on the functional aspects of treated platelets, and review clinical studies showing the clinical efficiency of the pathogen inactivation methods and their possible toxicity.

Evaluation in vitro de la fonction hémostatique des concentrés plaquettaires traités par inactivation des pathogènes par amotosalem-UVA

La transfusion de concentrés plaquettaires, dès 1958, a permis d'augmenter l'espérance et la qualité de vie des patients dans le domaine de l'onco-hématologie, notamment en réduisant les risques hémorragiques induits par les chimiothérapies intensives. Après le traumatisme de l'affaire du sang contaminé dans les années 1980-1990, la médecine transfusionnelle a adopté des exigences de sécurité et de qualité très strictes et régulées dans plusieurs pays par les instances politiques. Cependant même les mesures de qualité les plus strictes n'ont permis d'atteindre le risque « zéro », notamment en ce qui concerne les contaminations bactériennes. De plus, la prise de conscience de l'existence de nouveaux pathogènes (West Nile Virus, Chikungunya, Prions) a stimulé le développement de 3 techniques d'inactivation des pathogènes pouvant s'appliquer au plasma et aux concentrés plaquettaires : la technique INTERCEPT utilisant l'amotosalen/UVA, la technique MIRASOL avec la riboflavine/UV et la technique THERAFLEX avec les UVC. La Suisse a fait office de pionnière en étant le premier pays au monde à adopter de manière généralisée l'inactivation des pathogènes par la technique INTERCEPT pour les concentrés plaquettaires dès 2011 après sa validation par Swissmedic en 2009 et son implémentation réussie dans plusieurs centres de transfusion pilotes. Coïncidence? Le décès tragique d'un patient pédiatrique en 2009 suite à une contamination bactérienne par une transfusion de concentré plaquettaire a précédé cette décision. Les cliniciens ont besoin de disposer de concentrés plaquettaires sûrs d'un point de vue microbiologique mais également sur le plan hémostatique, d'où la nécessité de disposer de preuves solides sur l'efficacité thérapeutique de ces nouveaux produits. Ceci a fait l'objet de la revue publiée dans Blood Reviews « The clinical and biological impact of new pathogen inactivation technologies on platelets concentrates » dont l'originalité est de couvrir l'étude de l'effet des processus d'inactivation des pathogènes sur la fonction plaquettaire sous toutes ses facettes allant de la protéomique aux études d'hémovigilance. Ce travail montre l'efficacité de ces méthodes et leur sécurité et souligne que l'observation de taux de recirculation moindre peut être compensée par une augmentation du statut d'activation des plaquettes. Le deuxième article publié comme co-auteur dans le journal Blood Transfusion « In vitro evaluation of pathogen-inactivated buffy coat-derived platelet concentrates during storage: The psoralen-based photochemical treatment step-by-step » se pose la question de la modification des propriétés fonctionnelles des plaquettes dans une étude à deux bras (par comparaison entre plaquettes traitées et non traitées). En plus de deux tests utilisés en pratique clinique (agrégation plaquettaire et cytométrie de flux) un test expérimental d'adhésion plaquettaire au fibrinogène en condition statique a été développé en collaboration avec le Prof Angelillo-Scherrer dans le cadre du laboratoire de recherche et développement du SRTS-VD. Les résultats obtenus démontrent la conservation du métabolisme plaquettaire et des changements mineurs dans la capacité d'agrégation mais une augmentation de la capacité d'adhésion au fibrinogène des plaquettes traitées probablement via une augmentation de la conversion de l'intégrine ailb(B3 dans sa forme activée. Les techniques d'inactivation des pathogènes appliqués aux concentrés plaquettaires représentent un important progrès dans le domaine de la médecine transfusionnelle. Leur impact au niveau moléculaire reste cependant encore en partie inconnu et fait l'objet d'études. Le défi actuel consiste à réussir à les adopter aux concentrés érythrocytaires, ce qui révolutionnerait la médecine transfusionnelle.

Degradação e estabilização do diclofenaco em nanocápsulas poliméricas

The parameters which affect the degradation and stabilization of diclofenac in suspensions of nanocapsules and of the corresponding spray-dried powders were investigated. Formulations were subjected to 14 months of storage at room temperature. In addition, a study of the degradation of diclofenac was carried out by exposing the formulations or mixtures (drug and adjuvants) to UVC wavelengths. The presence of Epikuron 170® in a concentration higher than 3.06 mg/mL stabilizes the drug, avoiding its reduction or degradation. The degradation products were isolated, analyzed by gas chromatography-mass spectrometry, and identified as 2-(2',6'-dichlorophenyl)aminobenzyl alcohol and N-(2',6'-dichlorophenyl)anthranilylaldehyde.

Avaliação do potencial de processos oxidativos avançados para remediação de águas contaminadas com geosmina e 2-MIB

In this work, the efficiency of some homogeneous advanced oxidation processes (UVC/H2O2, Fe2+/H2O2, UVC/Fe2+/H2O2, UVA/Fe2+/H2O2, solar/Fe2+/H2O2) was investigated toward the degradation of geosmin and 2-methylisoborneol (2-MIB). The effect of relevant experimental parameters (ie. pH, Fe2+ and H2O2 concentration) was first investigated by factorial design, using camphor as a model substrate. In the geosmin and 2-MIB degradation studies the Fenton processes assisted by solar and UVA radiation offered the most promising results, mainly on account of high degradation capacity (higher than 80% at a reaction time of 60 min), high operational simplicity and low cost.

Catálise básica usando sílica mesoporosa estabilizada por acrilatos encapsulados

The synthesis of new type of silicas, with structures akin to that of MCM-41, containing polyacrylate-encapsulated micelles in their mesopores is reported. Initially, the monomers were inserted in the aqueous micelles of cetyltrimethylammonium cations. MCM-41 was then prepared in this microemulsion. Finally, the polymerization of the acrylates was initiated by UVC radiation. The presence of monomers and polymers in the interior of micelles in aqueous media were characterized by IR spectroscopy and small-angle Xray scattering. The presence of this polymer increased the stability of these new materials in catalytic transesterification.

Veden desinfiointi UV-LED-valolla

Veden riittämätön puhdistus aiheuttaa riskin veden käyttäjille. Miljoonia kuolemia vuosittain aiheuttavien vesiteitse leviävien sairauksien ehkäisemiseksi vaaditaan tehokkaita juomaveden desinfiointimenetelmiä. Kuivuuden ja väestönkasvun myötä veden tarve on lisääntynyt ja vedenkulutus tulee yhä kasvamaan. Tästä syystä mahdollisuus kierrättää vettä hyödyntäen sitä esimerkiksi kasteluun on saanut yhä enemmän huomiota. Kierrätettävä vesi on kuitenkin käsiteltävä huolellisesti sen sisältämän mikrobiologisen kontaminaatioriskin vuoksi. Ultraviolettisäteily luokitellaan fysikaaliseksi desinfiointimenetelmäksi. Sen tehokkuus perustuu mikro-organismien absorboimaan UV-säteilyyn, jonka aiheuttamien DNA:ssa tai RNA:ssa tapahtuvien muutoksien seurauksena mikro-organismi inaktivoituu ja estyy lisääntymästä. UV-desinfioinnissa on tyypillisesti käytetty elohopeahöyrylamppuja. Vaihtoehtoinen UV-säteilyn lähde ovat LEDit eli valoa emittoivat diodit. Matalapaine-elohopeahöyrylamppujen emittoima säteily on aallonpituudella 254 nm ja keskipaine-elohopeahöyrylamppujen emittoima säteily on laajakaistaista säteilyä. Energiatehokkuuden lisäksi LEDien etuna on, että niillä voidaan tuottaa kapeakaista säteilyä aallonpituudella, joka parhaiten absorboituu DNA:han. Tämän diplomityön tarkoituksena oli tutkia, onko UVC-alueen aallonpituuksien yhdistelmillä synergistisiä etuja LEDien desinfiointitehokkuuteen, kun desinfioidaan virtaavaa vettä useilla säteilyannoksilla ja indikaattorimikrobina käytetään kolibakteeria. Tavoitteena oli myös tutkia tällä hetkellä saatavissa olevien LEDien desinfiointitehokkuutta energiatehokkuuden näkökulmasta. Yksittäisistä aallonpituuksista desinfiointitehokkuudeltaan parhaimmaksi osoittautui 260 nm, aallonpituuksien yhdistelmistä tehokkain oli 265 nm:n ja 260 nm:n yhdistelmä. Muilla aallonpituuksien yhdistelmillä ei saavutettu odotettua parempaa desinfiointitehokkuutta. Optiselta teholtaan parhaimmat LEDit, 265 nm, 270 nm ja 275 nm olivat kokeiden perusteella myös energiatehokkuuden kannalta tarkasteltuina parhaimmat sekä yksittäin että yhdistelminä. UVC-aallonpituuksia emittoivien LEDien optisen tehokkuuden paraneminen on edellytys LEDien hyödyntämiselle desinfioinnissa.

The Combined treatment of UV Light and Titanium Dioxide (TiO2) in Grease Filtration Technique

The aim of this thesis was to identify the best grease removal technique with the application of low power of UV light to TiO2 coated grease filters. The treatment with various power series of ozone generating and ozone free lamps to normal grease filters and TiO2 coated grease filters were examined and the obtained results are compared to each other in this paper. The effect of ozone reaction was observed and compared with the effect of TiO2. The experiments were solely based on the photo oxidation and photo catalytic oxidation reactions. TiO2 is a green catalyst used in the photocatalytic reaction. Sunflower oil was used for grease production and tetracholoroethylene as a solvent. Grease samples were collected from the ventilation duct connected to the cooking hood system. Sample extraction was done in ultrasonic bath with the principle of sonication. The sample analysis was done by FTIR machine. The result determining the concentration of grease was the quantification of saturated C-H bonds in the chosen peak group of the spectrum. A very low power of UVC light functions perfectly with the Titanium dioxide. The experimental results have shown the combined treatment of titanium dioxide and UV light is an effective method in grease removal process. The photocatalytic reaction with titanium dioxide is better than photo oxidation reaction with ozone treatment. Photocatalytic reaction is environmentally friendly, energy efficient and economical.