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- ItemSomente MetadadadosAnálise molecular dos genes nid e cyp e avaliação da degradação de pireno por isolados de Mycobacterium sp(Universidade Federal de São Paulo, 2017-07-07) Silva, Natalia Maria da [UNIFESP]; Niero, Cristina Viana [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Polycyclic aromatic hydrocarbons (PAHs) are compounds found in the environment as a result of incomplete combustion of organic matter or the anthropogenic activity of exploration, refining and petroleum derivatives. They have complex structures with low solubility in water and remain for long periods in the environment being considered pollutants. Mycobacterium vanbaalenii-PYR1 was the first described microorganism with the ability to degrade pyrene, a polycyclic aromatic hydrocarbon. Sequencing of the genome of this strain revealed the presence of a region specialized in the degradation of HPA, called region A, containing genes encoding dioxygenase (nid). In addition, genes dispersed in the genome that encode monooxygenases (cyp150) with involvement in the degradation of these compounds have been described. Thus, this work investigated the presence of the nid and cyp genes in five Mycobacterium sp isolates by PCR and hybridizations with specific probes, besides the degradation of pyrene by phenotypic tests and by gas chromatography coupled to mass spectrometry (GC-MS). In the first stage of the work, the identification of the isolates was performed by the analysis of three essential genes by sequencing and the results obtained allowed to conclude that the isolates of this study are related to M. vanbaalenii and M. austroafricanum species. All isolates analyzed showed the ability to degrade pyrene by phenotypic tests. Gas chromatographic analyzes suggest that the MYC038, MYC040 and MYC211 isolates degrade 69.5%, 60.3% and 50.5% pyrene, respectively, over a period of 14 days. PCR results and hybridizations revealed the presence of only nidA and cyp150 genes in all isolates analyzed. The nidB, nidA3, nidB3 and ferredoxin phtAcAd genes were not identified in any of the isolates analyzed in this study suggesting their absence. Analyzes of the nidB2 gene did not allow to conclude its presence / absence. These data re-inforce the hypothesis of the present work that there is polymorphism in the A region of these isolates, and may also imply the existence of a new pathway for the degradation of aromatic hydrocarbons.
- ItemSomente MetadadadosAplicação do Percarbonato de Sódio no tratamento de efluente aquoso simulado contendo Amoxicilina utilizando processos oxidativos avançados(Universidade Federal de São Paulo (UNIFESP), 2020-10-29) Oliveira, Isaac Henrique Molina de [UNIFESP]; Moraes, José Ermirio Ferreira de [UNIFESP]; Universidade Federal de São PauloThe wastewater of the pharmaceutical industry, in many cases, contains residues of several medicines. Antibiotics, for example, are toxic substances that can trigger the growth of resistant microorganisms, leading to a serious public health problem. Advanced Oxidative Processes (AOP) have been widely studied for the treatment of this type of effluent, as they are methods based on the generation of hydroxyl radicals, a highly reactive species, able to destroy several toxic organicsseveral toxic organics. In the present work, the application of sodium percarbonate (SPC) was investigated, as a source of hydrogen peroxide, in the Fenton, photo-Fenton and UV/SPC processessource of hydrogen peroxide, in the Fenton, photo-Fenton and UV/SPC processes was investigated. Amoxicillin, which is one of the most consumed antibiotics in Brazil, was used as a model pollutant, simulating an effluent from the pharmaceutical industry, adopting an initial concentration of 100 mgC L-1. The tests were carried out in a batch system with recirculation, composed of a photochemical reactor coupled to a mixing tank. Experiments were carried out in order to evaluate the influence of the main parameters on the amoxicillin mineralization, such as pH (3 and 10), the type of iron ions source (Fe2+ and Fe3+), the initial concentration of iron ions (0.26; 1.0 and 2.0 mmol L-1) and UV radiation. According to the experimental data obtained, it was possible to observe that the application of SPC showed promising results in the oxidation of amoxicillin, showing mineralization percentages of 65.8% in just 30 minutes and 88.4% in 120 minutes of reaction, by conventional photo-Fenton process (using ions Fe2+). The use of the modified photo-Fenton process (using ions Fe3+) unfolded to be a viable alternative too, reaching a mineralization of 85.7% in 2 hours by the photo-Fenton process. The Doehlert experimental matrix was used to evaluate the modified Fenton and photo-Fenton processes (using ions Fe3+) systematically, evaluating the influence of the molar rate of the SPC solution in terms of the equivalent amount of H2O2 (0.730-2.205 mmolH2O2 min-1) and the initial concentration of ferric ions (0.26-1.56 mmol L-1) in the total organic carbon removal performance. According to the data obtained, for the Fenton process, the most favorable condition was with a high concentration of Fe3+ (1.560 mmol L-1) and a moderate SPC feed rate (1.470 mmolH2O2 min-1). In the case of the photo-Fenton process, for a better removal, low concentrations of Fe3+ (0.585 mmol L-1) and a moderate SPC feed rate (1.470 mmolH2O2 min-1) would be indicated.
- ItemSomente MetadadadosChlorhexidine Inhibits the Activity of Dental Cysteine Cathepsins(Sage Publications Inc, 2012-04-01) Scaffa, Polliana Mendes Candia; Vidal, Cristina de Mattos Pimenta; Barros, Nilana Meza Tenório de [UNIFESP]; Gesteira, Tarsis Ferreira [UNIFESP]; Carmona, Adriana Karaoglanovic [UNIFESP]; Breschi, Lorenzo; Pashley, David H.; Tjaderhane, Leo; Tersariol, Ivarne Luis dos Santos [UNIFESP]; Nascimento, Fábio Dupart; Carrilho, Marcela Rocha de Oliveira; Univ Bandeirante São Paulo; Universidade Estadual de Campinas (UNICAMP); Universidade Federal de São Paulo (UNIFESP); Univ Trieste; IGM CNR; IOR; Georgia Hlth Sci Univ; Univ Oulu; Oulu Univ Hosp; Univ Mogi das CruzesThe co-expression of MMPs and cysteine cathepsins in the human dentin-pulp complex indicates that both classes of enzymes can contribute to the endogenous proteolytic activity of dentin. Chlorhexidine (CHX) is an efficient inhibitor of MMP activity. This study investigated whether CHX could also inhibit cysteine cathepsins present in dentin. the inhibitory profile of CHX on the activity of dentin-extracted and recombinant cysteine cathepsins (B, K, and L) was monitored in fluorogenic substrates. the rate of substrate hydrolysis was spectrofluorimetrically measured, and inhibitory constants were calculated. Molecular docking was performed to predict the binding affinity between CHX and cysteine cathepsins. the results showed that CHX inhibited the proteolytic activity of dentin-extracted cysteine cathepsins in a dose-dependent manner. the proteolytic activity of human recombinant cathepsins was also inhibited by CHX. Molecular docking analysis suggested that CHX strongly interacts with the subsites S2 to S2' of cysteine cathepsins B, K, and L in a very similar manner. Taken together, these results clearly showed that CHX is a potent inhibitor of the cysteine cathepsins-proteolytic enzymes present in the dentin-pulp complex.
- ItemAcesso aberto (Open Access)Degradação de resíduo de levedura empregado em biossorção por processos eletro-oxidativos avançados(Universidade Federal de São Paulo, 2017-10-06) Bargas, Maria Francisca Ribeiro de Aguiar [UNIFESP]; Rodrigues, Christiane de Arruda [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)The use of agroindustrial waste as adsorbents has been evaluated as an alternative treatment of textile effluents, mainly for color removal. However, solutions are required for the proper fate of the adsorbent after sorption of the organic compound. In this way, the Advanced Oxidative Processes (POA) appear as an alternative of clean destination of the solid residues containing organic compound. The objective of this work was to evaluate the efficiency in the treatment of the degradation of dry yeast biomass, biosorbent from the residue of the sugar and alcohol industry, after the sorption of methylene blue reactive dye by means of photo-Fenton and heterogeneous photocatalysis (photocatalysis and photoelectrocatalysis) using a TiO2 nanotubular oxide layer as catalyst. The study was carried out with three yeast biomasses, washed yeast biomass (WYB), in nature Yeast Biomass (YB) and yeast biomass after the sorption of the methylene blue reactive dye (SYB). Initially the BL was washed with distilled water to remove the soluble residue in order to quantify the reduction of mass and mineralization only of the solid fraction. The optimization studies of the best conditions of degradation and mineralization of the organic matter were obtained with the WYB. The optimization studies of the best conditions of degradation and mineralization of the organic matter were obtained with the WYB. In the photo-Fenton process, the optimized condition was 2,500 mg L-1 of H2O2 and 40 mg L-1 of Fe2+ and 100 mg of biomass mass, with sequential addition of H2O2 during the degradation process, at 15 min intervals, during 2 hours of treatment, with a percentage of mineralization around 45% and destruction of the degraded biomass (lysed). While in heterogeneous photocatalysis, although there is no evidence of cell lysis, the photocatalytic treatment showed to be more efficient in reducing the organic load of the WYB and YB compared to the treatment by photoelectrocatalysis, with a mass reduction percentage of around 46,5% after 4 hours of treatment. In both studies, an irradiation source with a mercury vapor lamp of 80 W was used. Then, the combination of the optimized processes, photo-Fenton followed by photocatalysis, was employed in the treatment of YB and SYB. After the degradation, YB presented a reduction of mass and mineralization around 85% and SYB around 60% of mass reduction and 50% of mineralization. The combination of the photo-Fenton process followed by the heterogeneous photocatalysis showed to be a clean destination of solid residues formed by yeast biomass with adsorbed dye.
- ItemSomente MetadadadosDynamics of fipronil in Oleo Lagoon in Jatai Ecological Station, São Paulo-Brazil(Elsevier B.V., 2010-03-01) Peret, Andre Moldenhauer [UNIFESP]; Oliveira, Luciana Fontes [UNIFESP]; Bianchini, Irineu [UNIFESP]; Regali Seleghim, Mirna Helena [UNIFESP]; Peret, Alberto Carvalho [UNIFESP]; Mozeto, Antonio Aparecido [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Fipronil is a phenylpyrazole pesticide widely used to protect sugar-cane crops from insect pests. After reaching the environment, this insecticide may have several fates. This research aimed to propose a kinetic model to describe the fate of commercial fipronil Regent 800WG (R) in the sediment-water interface of the Oleo Lagoon in the Mogi-Guacu river floodplain, situated within the Jatai Ecological Station, by means of a microcosm scale experiment. Results showed that a small fraction of the pesticide is quickly dragged to the sediment while most of it remains in the water column. Biodegradation proves to be an important fipronil degradation route, especially when microorganisms capable of using fipronil as sole carbon source increase their population, as a function of exposure time. Biodegradation rates were higher in the sediment than in the water column. (C) 2009 Elsevier B.V. All rights reserved.
- ItemAcesso aberto (Open Access)Estabilidade das antocianinas de juçara: comparação entre os métodos de extração convencional e sistema aquoso bifásico(Universidade Federal de São Paulo, 2018-12-04) Camargo, Marília Ceolin [UNIFESP]; Braga, Anna Rafaela Cavalcante [UNIFESP]; http://lattes.cnpq.br/1145965338858435As antocianinas são polifenóis, pertencentes a classe dos flavonoides, encontrados em plantas superiores, capazes de promover a saúde humana, no entanto, os efeitos das antocianinas em nossa saúde dependem da quantidade consumida e da sua biodisponibilidade. Muitas pesquisas demonstram o potencial antioxidante das antocianinas, além de sua capacidade em combater doenças crônicas neurodegenerativas, cardiovasculares e diabetes. Além das antocianinas serem benéficas a saúde, as mesmas também podem ser empregadas na indústria de cosméticos, farmacêutica e alimentícia como corantes naturais, e na prevenção contra a auto oxidação e peroxidação de lipídeos em sistemas biológicos, entretanto a sua utilização nas industrias ainda é restrita devido à sua baixa estabilidade. Sabe-se que as antocianinas são moléculas muito instáveis físico-quimicamente, e que alguns fatores como a luz, pH, temperatura, presença de oxigênio e de outros íons e moléculas podem causar a sua degradação, além do mais os processos de extração, manipulação, recuperação, purificação e armazenamento também podem influenciar na sua degradação. O estudo da estabilidade térmica das antocianinas obtidas por métodos não convencionais faz-se necessário, a fim de obter métodos mais eficientes e com custo inferior as obtidas pelos métodos convencionais. A polpa dos frutos da palmeira Euterpe edulis Mart., conhecida como juçara, foi escolhida como fonte de antocianinas no desenvolvimento deste estudo, o qual visa comparar a estabilidade térmica das antocianinas extraídas por um método convencional, no qual foi utilizado metanol acidificado, em contraposição ao sistema aquoso bifásico (SAB), em que se empregou polietilenoglicol (PEG)/fosfato de potássio. A partir da análise de degradação térmica foi evidenciado que a estabilidade das antocianinas extraídas utilizando o SAB foi superior, considerando os parâmetros avaliados no presente estudo. A energia térmica de desnaturação e a meia vida, tal como o teor de antocianinas extraídas excedeu àquelas alcançadas pelo método convencional, por conseguinte, o sistema aquoso bifásico apresentou-se como uma excelente alternativa para a extração desse pigmento.
- ItemAcesso aberto (Open Access)Fontes de contaminação de microplásticos e avaliação de possíveis métodos de tratamento de água e efluentes(Universidade Federal de São Paulo, 2022-12-16) Oliveira, Mariana Silva de [UNIFESP]; Paz, Thais Clear da Silva Ferreira [UNIFESP]; Ribeiro, Katia [UNIFESP]; http://lattes.cnpq.br/6490500674409303Como consequência do consumo excessivo e descarte de materiais plásticos não biodegradáveis no meio ambiente, o crescimento da poluição e contaminação causada por esses componentes se torna preocupante. Um dos principais resíduos e foco da presente revisão, é o microplástico, partícula microscópica com tamanho menor que 5 mm. Essas partículas são divididas em duas categorias: primários, os já produzidos nessa escala para aplicação em cosméticos e produtos de higiene; e os secundários, gerados a partir da degradação de plásticos comuns. Estudos recentes já determinaram a presença desses compostos em ar atmosférico, água potável e em mares e rios, no entanto, pouco se sabe sobre os efeitos na saúde dos seres vivos, podendo ser relacionados a doenças como obesidade e problemas respiratórios. A fim de entender formas de contaminação e de tratamento, foram mapeadas possíveis fontes de emissão de microplásticos no meio ambiente, como aterros sanitários, descarte inadequado de resíduos, estações de tratamento de efluentes e opções de remoção e descontaminação, seja por métodos convencionais como coagulação, flotação ou com o emprego de mecanismos inovadores como partículas marinhas biogênicas. Com o objetivo de analisar os métodos abordados, alguns parâmetros como tamanho e composição dos microplásticos e eficiência de remoção foram comparados. Notou-se que, se tratando de métodos convencionais, já utilizados nas estações de tratamento de água, os métodos de flotação se destacam em relação à eficácia. Já se tratando de métodos biológicos de degradação, o experimento com organosilanos obteve resultados bastante promissores, foram retidos 85% dos microplásticos presentes. Por fim, uma abordagem que combine algum dos métodos físico-químicos com um método de degradação por microrganismos específicos pôde ser sugerida como tema de futuros estudos.
- ItemSomente MetadadadosIncorporation of bioactive glass in calcium phosphate cement: Material characterization and in vitro degradation(Wiley-Blackwell, 2013-08-01) Renno, Ana Claudia Muniz [UNIFESP]; Nejadnik, M. R.; van de Watering, F. C. J.; Crovace, Murilo Camuri; Zanotto, Edgar Dutra; Hoefnagels, J. P. M.; Wolke, J. G. C.; Jansen, J. A.; van den Beucken, Jeroen J. J. P.; Radboud Univ Nijmegen; Universidade Federal de São Paulo (UNIFESP); Universidade Federal de São Carlos (UFSCar); Eindhoven Univ Technol TU ECalcium phosphate cements (CPCs) have been widely used as an alternative to biological grafts due to their excellent osteoconductive properties. Although degradation has been improved by using poly(D,L-lactic-co-glycolic) acid (PLGA) microspheres as porogens, the biological performance of CPC/PLGA composites is insufficient to stimulate bone healing in large bone defects. in this context, the aim of this study was to investigate the effect of incorporating osteopromotive bioactive glass (BG; up to 50 wt %) on setting properties, in vitro degradation behavior and morphological characteristics of CPC/BG and CPC/PLGA/BG. the results revealed that the initial and final setting time of the composites increased with increasing amounts of incorporated BG. the degradation test showed a BG-dependent increasing effect on pH of CPC/BG and CPC/PLGA/BG pre-set scaffolds immersed in PBS compared to CPC and CPC/PLGA equivalents. Whereas no effects on mass loss were observed for CPC and CPC/BG pre-set scaffolds, CPC/PLGA/BG pre-set scaffolds showed an accelerated mass loss compared with CPC/PLGA equivalents. Morphologically, no changes were observed for CPC and CPC/BG pre-set scaffolds. in contrast, CPC/PLGA and CPC/PLGA/BG showed apparent degradation of PLGA microspheres and faster loss of integrity for CPC/PLGA/BG pre-set scaffolds compared with CPC/PLGA equivalents. Based on the present in vitro results, it can be concluded that BG can be successfully introduced into CPC and CPC/PLGA without exceeding the setting time beyond clinically acceptable values. All injectable composites containing BG had suitable handling properties and specifically CPC/PLGA/BG showed an increased rate of mass loss. Future investigations should focus on translating these findings to in vivo applications. (c) 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
- ItemSomente MetadadadosMethodologies for characterization of aerospace polymers/energetic materials - a short review(Inst aeronautica & espaco-iae, 2016) Pedreira, Shirley Motta; Aguiar Pinto, Juliano Ribeiro; Campos, Eunice Aparecida; Mattos, Elizabeth da Costa; Oliveira Junior, Mauro Santos de [UNIFESP]; Sampaio de Oliveira, Jose Irineu; Lazzarini Dutra, Rita de CassiaFourier transform infrared spectroscopy techniques, associated or not to others, are a well-studied subject used for characterizing polymers/energetic materials that have been employed mainly in aerospace industries. However, the infrared analyses are usually qualitative and performed using the mid-infrared. This paper discusses the Fourier transform infrared spectroscopy qualitative and quantitative methodologies, coupled or not with thin layer chromatography and thermogravimetric analysis, for characterization of aerospace polymer systems, in some cases, using mid-infrared, near-infrared and far-infrared regions, by traditional accessories and the latest generation spectra mode, universal attenuated total reflection. This short review was made based on methodologies developed during the last two decades and published by many scientific and industrial research groups, emphasizing studies usually carried out in the last five years. A critical assessment and future trends were included.
- ItemAcesso aberto (Open Access)Molecular structure and antibacterialactivity of degradation products from cephalexin solutions submitted to thermal and photolytic stress(Willey, 2022-11-21) da Silva, Emerson Rodrigo [UNIFESP]; Valêncio, André [UNIFESP]; Machado, Marcelo Ferreira Marcondes [UNIFESP]; Miranda, Antonio [UNIFESP]; http://lattes.cnpq.br/7800589206457326; http://lattes.cnpq.br/0596334947896054; http://lattes.cnpq.br/9703373400186586; http://lattes.cnpq.br/1357848049935882; Lourenço, Cecília; Souza, Louise E. A.Cephalexin is a beta-lactam antibiotic of the first generation of cephalosporins which is very effective against various bacterial infections. In this work, we investigate the structure and antibacterial activity of cephalexin solutions submitted to forced degradation under heat stress and photolytic irradiation. A combination of analytical techniques gathering LC/ESI-MS and NMR spectroscopy allowed us to identify different chemical species amongst the byproducts, revealing that photolysis via UV light leads to significant amounts of oxidized species that conserve the dihydrothiazine ring adjacent to the beta-lactam ring. In contrast, thermodegradation induces the rupture of the bioactive moiety possibly with the production of cephalosporinic acid and deaminated species, which are inactive to bacteria. Microbiological analyses using E. coli as a model organism indicated that the antimicrobial capacity of samples submitted to thermolysis is suppressed while solutions submitted to irradiation with UVA light preserve their bactericidal power. Atomic force microscopy showed that cells incubated with photodegraded cephalexin are much longer than those incubated with the undegraded antibiotic, indicating that byproducts from photolysis inhibit septum formation and likely affect the action of penicillin-binding protein 3 in the divisome of E. coli cells.
- ItemSomente MetadadadosOptimizing dentin bond durability: Control of collagen degradation by matrix metalloproteinases and cysteine cathepsins(Elsevier B.V., 2013-01-01) Tjaderhane, Leo; Nascimento, Fabio D.; Breschi, Lorenzo; Mazzoni, Annalisa; Tersariol, Ivarne L. S. [UNIFESP]; Geraldeli, Saulo; Tezvergil-Mutluay, Arzu; Carrilho, Marcela R.; Carvalho, Ricardo M.; Tay, Franklin R.; Pashley, David H.; Univ Oulu; Oulu Univ Hosp; Nord Inst Dent Mat NIOM; Univ Bandeirante São Paulo; Univ Trieste; IGM CNR; Rizzoli Orthoped Inst; Univ Mogi das Cruzes; Universidade Federal de São Paulo (UNIFESP); Univ Florida; Univ Turku; Turku Univ Hosp; Univ Western Ontario; Univ British Columbia; Med Coll GeorgiaObjectives. Contemporary adhesives lose their bond strength to dentin regardless of the bonding system used. This loss relates to the hydrolysis of collagen matrix of the hybrid layers. the preservation of the collagen matrix integrity is a key issue in the attempts to improve the dentin bonding durability.Methods. Dentin contains collagenolytic enzymes, matrix metalloproteinases (MMPs) and cysteine cathepsins, which are responsible for the hydrolytic degradation of collagen matrix in the bonded interface.Results. the identities, roles and function of collagenolytic enzymes in mineralized dentin has been gathered only within last 15 years, but they have already been demonstrated to have an important role in dental hard tissue pathologies, including the degradation of the hybrid layer. Identifying responsible enzymes facilitates the development of new, more efficient methods to improve the stability of dentin-adhesive bond and durability of bond strength.Significance. Understanding the nature and role of proteolytic degradation of dentin-adhesive interfaces has improved immensely and has practically grown to a scientific field of its own within only 10 years, holding excellent promise that stable resin-dentin bonds will be routinely available in a daily clinical setting already in a near future. (c) 2012 Academy of Dental Materials. Published by Elsevier B.V. All rights reserved.
- ItemSomente MetadadadosPhotoelectrocatalytic oxidation of methyl orange on a tio2 nanotubular anode using a flow cell(Wiley-v c h verlag gmbh, 2016) Jose Martin de Vidales, Maria; Mais, Laura; Saez, Cristina; Canizares, Pablo; Walsh, Frank C.; Rodrigo, Manuel A.; Rodrigues, Christiane de Arruda [UNIFESP]; de Leon, Carlos PonceMethyl orange from water was removed by photocatalytic anodic oxidation using a titanium dioxide array surface. The coating was prepared by anodizing a titanium plate in an ethylene glycol electrolyte-containing NH4F followed by heat treatment to realize a photocatalytic surface under UV light. Scanning electron microscopy imaging showed that the array coating consisted of closely spaced nanotubes perpendicular to the titanium plate. The aqueous solution of methyl orange was circulated through a rectangular channel flow cell containing the coated anode. The effects of electrolyte flow rate and applied potential on the oxidation rate and efficiency were evaluated. At higher mean linear flow rates, the efficiency of the oxidation process improved, indicating a mass transport-controlled process. At more positive applied potentials, the TiO2 structure deteriorated resulting in a lower oxidation efficiency.
- ItemRestritoUma revisão sobre o potencial de co-culturas fúngicas na degradação de lignina(Universidade Federal de São Paulo, 2022-01-28) Soares, Jullio Kennedy Castro [UNIFESP]; Vallim, Marcelo Afonso [UNIFESP]; Vitali, Vera Maria Valle; http://lattes.cnpq.br/6137997220541039; http://lattes.cnpq.br/4039129182586680; http://lattes.cnpq.br/2102381380357788Atualmente a biomassa lignocelulósica corresponde a uma fonte de recurso altamente abundante e renovável, porém, sendo pouca explorada devido à recalcitrância fornecida pelo componente da lignina presente na parede vegetal, a qual pode ser superada pela degradação por co-culturas fúngicas que gradativamente estão sendo estudadas devido a maior produção de enzimas ligninolíticas, em detrimento das culturas axênicas, responsáveis pela modificação do polímero. Devido a isto, o objetivo deste trabalho é compilar os estudos experimentais de co-cultivos fúngicos na degradação da lignina e, para isto, foi adotado a metodologia de revisão da literatura do tipo sistemática buscando em onze bases de dados e mecanismos de busca os termos correspondente a este ramo de pesquisa para o levantamento de artigos científicos relevantes, publicados virtualmente nas últimas três décadas, os quais foram verificados por algumas etapas de triagem. Uma vez selecionados, os artigos científicos ainda foram submetidos à técnica Bola de Neve para a otimização da recuperação de estudos relevantes. Dentre os 43 estudos elegíveis que serviram de base para esta revisão, foi observado uma maior frequência de co-culturas fúngicas consideradas neutras (54,5%) e sinérgicas (39,8%), seguido dos raros co-cultivos antagônicos (5,7%), quanto à sua capacidade de degradar a lignina em comparação aos respectivos cultivos axênicos. Em geral, o resultado do co-cultivo se demonstra relacionado com o equilíbrio ou desbalanço dos efeitos antagônicos da competição/estresse e efeitos sinérgicos das alterações fisiológicas favoráveis. Por mais que se tenha conhecimento que as espécies pareadas, em conjunto com as condições microambientais do sistema, sejam responsáveis pelas degradabilidades relatadas, os mecanismos moleculares subjacentes às interações ainda permanecem incompreendidos. Além disso, também foi acompanhada, em geral, frequências similares para os resultados dos co-cultivos fúngicos sobre a degradação da holocelulose, decorrentes do aumento de enzimas hidrolíticas, e perda de biomassa dos substrato, em relação às correspondentes culturas isoladas. Em suma, os achados demonstram a aplicabilidade promissora de co-culturas fúngicas em setores biotecnológicos que visam intensificar a degradação de lignina e seus derivados, mediante a sua melhor compreensão em escala ecológica e industrial para a exploração de seu potencial biológico.
- ItemSomente MetadadadosStrategies to prevent hydrolytic degradation of the hybrid layer-A review(Elsevier B.V., 2013-10-01) Tjaderhane, Leo; Nascimento, Fabio D.; Breschi, Lorenzo; Mazzoni, Annalisa; Tersariol, Ivarne L. S. [UNIFESP]; Geraldeli, Saulo; Tezvergil-Mutluay, Arzu; Carrilho, Marcela; Carvalho, Ricardo M.; Tay, Franklin R.; Pashley, David H.; Univ Oulu; Univ Turku; NordicInst Dent Mat NIOM; Biomat Res Grp UNIBAN; Univ Trieste; IGM CNR; Univ Mogi das Cruzes; Universidade Federal de São Paulo (UNIFESP); Univ Florida; Univ Western Ontario; Univ British Columbia; Med Coll GeorgiaObjective. Endogenous dentin collagenolytic enzymes, matrix metalloproteinases (MMPs) and cysteine cathepsins, are responsible for the time-dependent hydrolysis of collagen matrix of hybrid layers. As collagen matrix integrity is essential for the preservation of long-term dentin bond strength, inhibition of endogenous dentin proteases is necessary for durable resin-bonded restorations.Methods. Several tentative approaches to prevent enzyme function have been proposed. Some of them have already demonstrated clinical efficacy, while others need to be researched further before clinical protocols can be proposed. This review will examine both the principles and outcomes of techniques to prevent collagen hydrolysis in dentin-resin interfaces.Results. Chlorhexidine, a general inhibitor of MMPs and cysteine cathepsins, is the most tested method. in general, these experiments have shown that enzyme inhibition is a promising approach to improve hybrid layer preservation and bond strength durability. Other enzyme inhibitors, e. g. enzyme-inhibiting monomers, may be considered promising alternatives that would allow more simple clinical application than chlorhexidine. Crosslinking collagen and/or dentin matrix-bound enzymes could render hybrid layer organic matrices resistant to degradation. Alternatively, complete removal of water from the hybrid layer with ethanol wet bonding or biomimetic remineralization should eliminate hydrolysis of both collagen and resin components.Significance. Understanding the function of the enzymes responsible for the hydrolysis of hybrid layer collagen has prompted several innovative approaches to retain hybrid layer integrity and strong dentin bonding. the ultimate goal, prevention of collagen matrix degradation with clinically applicable techniques and commercially available materials may be achievable in several ways. (C) 2013 Academy of Dental Materials. Published by Elsevier B.V. All rights reserved.