RESUMO
Detailed information about concrete behavior in real structures is an important issue in controlling its performance during its service life, and the use of embedded sensors to obtain desired information such as temperature, onset of the cracking process and evolution of strains, has gained the attention of the building concrete industry. Data obtained using this technology can provide valuable information for decision making about the need for corrective interventions that can ensure the integrity and safety of concrete structures for long period of time. This paper presents a review of the current state-of-the-art of embedded fiber optic sensors used to assess concrete information of a wide range of aspects, comprising: existing alternative technologies, characteristics and advantages, practical applications and future developments. Complementarily, the work presents preliminary results of the use of fiber optic sensors to automatically and continuously perform expansion readings of AAR in concrete elements that facilitate both the storage-with elimination of the usual interruptions for manual readings-and the availability of continuous results of expansion data that are not possible to obtain with usual AAR tests code reading recommendations.
RESUMO
Knowledge and lessons from past accidental exposures in radiotherapy are very helpful in finding safety provisions to prevent recurrence. Disseminating lessons is necessary but not sufficient. There may be additional latent risks for other accidental exposures, which have not been reported or have not occurred, but are possible and may occur in the future if not identified, analyzed, and prevented by safety provisions. Proactive methods are available for anticipating and quantifying risk from potential event sequences. In this work, proactive methods, successfully used in industry, have been adapted and used in radiotherapy. Risk matrix is a tool that can be used in individual hospitals to classify event sequences in levels of risk. As with any anticipative method, the risk matrix involves a systematic search for potential risks; that is, any situation that can cause an accidental exposure. The method contributes new insights: The application of the risk matrix approach has identified that another group of less catastrophic but still severe single-patient events may have a higher probability, resulting in higher risk. The use of the risk matrix approach for safety assessment in individual hospitals would provide an opportunity for self-evaluation and managing the safety measures that are most suitable to the hospital's own conditions.
Assuntos
Exposição Ambiental/prevenção & controle , Segurança do Paciente , Radioterapia/efeitos adversos , Medição de Risco/métodos , Humanos , Funções VerossimilhançaRESUMO
Epidemiological studies demonstrate an association between chronic consumption of arsenic contaminated water and cognitive deficits, especially when the exposure takes place during childhood. This study documents structural changes and nitrergic deficits in the striatum of adult female Wistar rats exposed to arsenic in drinking water (3 ppm, approximately 0.4 mg/kg per day) from gestation, throughout lactation and development until the age of 4 months. Kainic acid injected animals (10mg/kg, i.p.) were also analyzed as positive controls of neural cell damage. Morphological characteristics of cells, fiber tracts and axons were analyzed by means of light microscopy as well as immunoreactivity to neuronal nitric oxide synthase (nNOS). As nitrergic markers, nitrite/nitrate concentrations, nNOS levels and expression of nNOS-mRNA were quantified in striatal tissue. Reactive oxygen species (ROS) and lipid peroxidation (LPx) were determined as oxidative stress markers. Arsenic exposure resulted in moderate to severe alterations of thickness, organization, surrounding space and shape of fiber tracts and axons, while cell bodies remained healthy. These anomalies were not accompanied by ROS and/or LPx increases. By contrast, except the expression of nNOS-mRNA, all nitrergic markers including striatal nNOS immunoreactivity presented a significant decrease. These results indicate that arsenic targets the central nitrergic system and disturbs brain structural organization at low exposure levels.
Assuntos
Arsenitos/toxicidade , Corpo Estriado/efeitos dos fármacos , Neurônios Nitrérgicos/efeitos dos fármacos , Óxido Nítrico/metabolismo , Efeitos Tardios da Exposição Pré-Natal , Compostos de Sódio/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Corpo Estriado/enzimologia , Corpo Estriado/patologia , Agonistas de Aminoácidos Excitatórios/toxicidade , Feminino , Idade Gestacional , Ácido Caínico/toxicidade , Lactação , Peroxidação de Lipídeos/efeitos dos fármacos , Nitratos/metabolismo , Neurônios Nitrérgicos/enzimologia , Neurônios Nitrérgicos/patologia , Óxido Nítrico Sintase/metabolismo , Óxido Nítrico Sintase Tipo I , Nitritos/metabolismo , Gravidez , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismoRESUMO
We studied the effects of chronic arsenic exposure on brain monoamines and plasma levels of adrenocorticotropic hormone (ACTH) of mice. After weaning, mice received arsenic (0, 20, 40, 60 or 100 ppm) in drinking water over a period of 9 weeks. Monoamine content was quantified in different brain regions, arsenic was quantified in brain tissue and ACTH levels in plasma. Brain arsenic concentrations up to 200 ng/g showed a significant correlation with exposure levels and produced slight modifications in regional monoamine levels. ACTH plasma levels were significantly associated with norepinephrine (NE) concentrations in the medulla and pons, but not with hypothalamic NE levels. ACTH levels were significantly higher in the group exposed to 20 ppm. Dopamine showed significant dose-related decreases in the hypothalamus. These results show that chronic sodium arsenite exposure produces changes in central monoamines, which are not associated on a dose-dependent basis with major alterations in plasma ACTH.
Assuntos
Hormônio Adrenocorticotrópico/efeitos dos fármacos , Arsenitos/toxicidade , Monoaminas Biogênicas/metabolismo , Química Encefálica/efeitos dos fármacos , Ácido 3,4-Di-Hidroxifenilacético/metabolismo , Hormônio Adrenocorticotrópico/sangue , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Dopamina/metabolismo , Relação Dose-Resposta a Droga , Ácido Hidroxi-Indolacético/metabolismo , Hipotálamo/efeitos dos fármacos , Hipotálamo/metabolismo , Masculino , Bulbo/efeitos dos fármacos , Bulbo/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Norepinefrina/metabolismo , Ponte/efeitos dos fármacos , Ponte/metabolismo , Serotonina/metabolismoRESUMO
The gene INV1 encoding invertase from the yeast Candida utilis has been cloned using a homologous PCR hybridization probe, amplified with two sets of degenerate primers designed considering sequence comparisons between yeast invertases. The cloned gene was sequenced and found to encode a polypeptide of 533 amino acids that contain a 26 amino-acid signal peptide and 12 potential N-glycosylation sites. The nucleotide sequences of the 5' and 3' non-coding regions were found to contain motifs probably involved in initiation, regulation and termination of gene transcription. The amino-acid sequence shows significant identity with other yeast, bacterial and plant beta-fructofuranosidases. The INV1 gene from C. utilis was able to complement functionally the suc2 mutation of S. cerevisiae.
Assuntos
Candida/genética , Glicosídeo Hidrolases/genética , Sequência de Aminoácidos , Sequência de Bases , Southern Blotting , Candida/enzimologia , Clonagem Molecular , Primers do DNA/química , Glicosídeo Hidrolases/química , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Filogenia , Reação em Cadeia da Polimerase , Sinais Direcionadores de Proteínas/química , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , beta-FrutofuranosidaseRESUMO
We report here the development of an auxotrophic transformation system for the food yeast Candida utilis. To facilitate molecular studies in Candida utilis, we isolated auxotrophic strains for uracil biosynthesis by the combination of NTG-mutagenesis and 5-fluorotic acid (FOA) selection. The ura-mutation could be functionally complemented by the homologous URA3 gene. We used both, LiAc and electroporation methods to direct insertions at the ura3 locus through homologous recombination.
Assuntos
Candida/genética , Transformação Genética , Southern Blotting , Candida/crescimento & desenvolvimento , Eletroporação , Proteínas Fúngicas/genética , Vetores Genéticos , Lítio , Mutação , Plasmídeos/genética , Uracila/biossínteseRESUMO
A periplasmic invertase from the yeast Candida utilis was purified to homogeneity from cells fully derepressed for invertase synthesis. The enzyme was purified by successive Sephacryl S-300, and affinity chromatography and shown to be a dimeric glycoprotein composed of two identical monomer subunits with an apparent molecular mass of 150 kDa. After EndoH treatment, the deglycosylated protein showed an apparent molecular weight of 60 kDa. The apparent K(m) values for sucrose and raffinose were 11 and 150 mM, respectively, similar to those reported in Saccharomyces cerevisiae. The range of optimum temperature was 60-75 degrees C. The optimum pH was 5.5 and the enzyme was stable over pH range 3-6.
Assuntos
Candida/enzimologia , Glicosídeo Hidrolases/isolamento & purificação , Glicosídeo Hidrolases/metabolismo , Southern Blotting , Candida/química , Candida/crescimento & desenvolvimento , Glucose/metabolismo , Glicerol/metabolismo , Glicosídeo Hidrolases/genética , Glicosilação , Cinética , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae/enzimologia , Especificidade por Substrato , Temperatura , beta-FrutofuranosidaseRESUMO
A DNA fragment containing a transcription regulating region of the alcohol oxidase (AOX1) gene from the methylotrophic yeast Pichia pastoris was used in the construction of a vector for the expression of heterologous proteins in the methylotrophic yeast Hansenula polymorpha. We used this vector to clone the SUC2 gene from Saccharomyces cerevisiae into H. polymorpha yeast. The culture conditions for invertase production using a fed-batch culture were studied. More than 1.5 x 10(3) U/ml of biologically active invertase (1 g/l) were secreted to the cellular periplasmic space. The fermentative process was scaled up to 50 l. Invertase produced from H. polymorpha was glycosylated, but it contained significantly less carbohydrate than protein produced by S. cerevisiae. Using the Western-blot technique, it was observed that invertase secreted from H. polymorpha and invertase secreted from S. cerevisiae showed common antigenic determinants.
Assuntos
Glicosídeo Hidrolases/metabolismo , Pichia/metabolismo , Oxirredutases do Álcool/genética , Compartimento Celular , Meios de Cultura , Regulação Fúngica da Expressão Gênica , Genes Fúngicos , Vetores Genéticos , Glicerol/farmacologia , Glicosídeo Hidrolases/genética , Metanol/metabolismo , Pichia/efeitos dos fármacos , Pichia/genética , Pichia/crescimento & desenvolvimento , Regiões Promotoras Genéticas , Proteínas Recombinantes de Fusão/metabolismo , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/genética , beta-FrutofuranosidaseRESUMO
A method to obtain K. marxianus mutants has been developed. Different auxotrophic mutants were isolated by nystatin and snail-enzyme enrichment procedures using an incubation time of 2 h before adding the antibiotic or the enzyme respectively. All his mutants analyzed by complementation tests turned out to belong to the same complementation group. Some of them were transformed and complemented by the S. cerevisiae HIS3 gene. These non-reverting his3 mutants contain no heterologous sequence, which is essential to make them acceptable for application in the food industry.
Assuntos
Kluyveromyces/genética , Mutação , Transformação Genética , Genes Fúngicos , Teste de Complementação Genética , Histidina/genética , Mutagênese , Plasmídeos/genética , Mapeamento por Restrição , Saccharomyces cerevisiae/genéticaRESUMO
We have cloned and expressed a bacterial thermostable alpha amylase gene in Pichia pastoris using the methanol-controlled alcohol oxidase (AOX1) promoter. Two integrative vectors were constructed with two different secretion signal sequences in order to obtain efficient secretion of the protein. One vector contains the structural gene encoding the mature alpha amylase fused to the SUC2 gene signal sequence from Saccharomyces cerevisiae. In the other vector, the alpha amylase is expressed with its own signal sequence. In both cases, the alpha amylase were secreted into the culture medium with high efficiency, around 2.5 and 0.9 g/l respectively.