ß-Lactams: chemical structure, mode of action and mechanisms of resistance

This synopsis summarizes the key chemical and bacteriological characteristics of β-lactams, penicillins, cephalosporins, carbanpenems, monobactams and others. Particular notice is given to first-generation to fifth-generation cephalosporins. This review also summarizes the main resistance mechanism to antibiotics, focusing particular attention to those conferring resistance to broad-spectrum cephalosporins by means of production of emerging cephalosporinases (extended-spectrum β-lactamases and AmpC β-lactamases), target alteration (penicillin-binding proteins from methicillin-resistant Staphylococcus aureus) and membrane transporters that pump β-lactams out of the bacterial cell.

After Bologna: does the shift in structure bring forth a shift in a attitude?

With this case-study, we (i) intend to show how a semester project on creating a Multimedia CV could, to some extent, help Portuguese final-year students develop some generic competences, change their attitude towards the challenge of "How to Apply fro a Job" and increase their self-marketing strategies, creativity and entrepreneurship cannot answer the question of the paper, but intend onlu to raise it fot further and better studies now that Bologna design is implementes in almost all HEIs Europe.

Antioxidant properties of hydroxycinnamic acids: a review of structure- activity relationships

Hydroxycinnamic acids (HCAs) are important phytochemicals possessing significant biological properties. Several investigators have studied in vitro antioxidant activity of HCAs in detail. In this review, we have gathered the studies focused on the structure-activity relationships (SARs) of these compounds that have used medicinal chemistry to generate more potent antioxidant molecules. Most of the reports indicated that the presence of an unsaturated bond on the side chain of HCAs is vital to their activity. The structural features that were reported to be of importance to the antioxidant activity were categorized as follows: modifications of the aromatic ring, which include alterations in the number and position of hydroxy groups and insertion of electron donating or withdrawing moieties as well as modifications of the carboxylic function that include esterification and amidation process. Furthermore, reports that have addressed the influence of physicochemical properties including redox potential, lipid solubility and dissociation constant on the antioxidant activity were also summarized. Finally, the pro-oxidant effect of HCAs in some test systems was addressed. Most of the investigations concluded that the presence of ortho-dihydroxy phenyl group (catechol moiety) is of significant importance to the antioxidant activity, while, the presence of three hydroxy groups does not necessarily improve the activity. Optimization of the structure of molecular leads is an important task of modern medicinal chemistry and its accomplishment relies on the careful assessment of SARs. SAR studies on HCAs can identify the most successful antioxidants that could be useful for management of oxidative stress-related diseases.

β-Lactams: chemical structure, mode of action and mechanisms of resistance

This synopsis summarizes the key chemical and bacteriological characteristics of β-lactams, penicillins, cephalosporins, carbanpenems, monobactams and others. Particular notice is given to first-generation to fifth-generation cephalosporins. This reviewalso summarizes the main resistancemechanism to antibiotics, focusing particular attention to those conferring resistance to broad-spectrum cephalosporins by means of production of emerging cephalosporinases (extended-spectrum β-lactamases and AmpC β-lactamases), target alteration (penicillin-binding proteins from methicillin-resistant Staphylococcus aureus) and membrane transporters that pump β-lactams out of the bacterial cell.

The effect of fractional order in variable structure control

This paper studies fractional variable structure controllers. Two cases are considered namely, the sliding reference model and the control action, that are generalized from integer into fractional orders. The test bed consists in a mechanical manipulator and the effect of the fractional approach upon the system performance is evaluated. The results show that fractional dynamics, both in the switching surface and the control law are important design algorithms in variable structure controllers.

Modelização de equivalente eléctrico para rede de nervuras de folhas vegetais

A tese tem como objectivo principal a criação de um modelo equivalente eléctrico da rede de nervuras de algumas folhas vegetais e analisar o seu comportamento a estímulos eléctricos, analisando-se também a respectiva resposta em frequência. A motivação desta tese passa pela observação dos sistemas existentes na natureza. Neste caso, as folhas vegetais e analisar se são sistemas de ordem fraccionária ou não. Para a sua elaboração, fez-se uma breve abordagem à estrutura das plantas, sob o ponto de vista da botânica e elaborou-se um método de fotografia das amostras, mapeamento da rede de nervuras e medição dos segmentos que compõem essa mesma rede. A tese termina com um capítulo de resultados experimentais.

Evolution of Drug Resistance: Insight on TEM -Lactamases Structure and Activity and Beta-Lactam Antibiotics

Extended-spectrum β-lactamases (ESBLs) prevalence was studied in the north of Portugal, among 193 clinical isolates belonging to citizens in a district in the boundaries between this country and Spain from a total of 7529 clinical strains. In the present study we recovered some members of Enterobacteriaceae family, producing ESBL enzymes, including Escherichia coli (67.9%), Klebsiella pneumoniae (30.6%), Klebsiella oxytoca (0.5%), Enterobacter aerogenes (0.5%), and Citrobacter freundii (0.5%). β-lactamases genes blaTEM, blaSHV, and blaCTX-M were screened by polymerase chain reaction (PCR) and sequencing approaches. TEM enzymes were among the most prevalent types (40.9%) followed by CTX-M (37.3%) and SHV (23.3%). Among our sample of 193 ESBL-producing strains 99.0% were resistant to the fourth-generation cephalosporin cefepime. Of the 193 isolates 81.3% presented transferable plasmids harboring genes. Clonal studies were performed by PCR for the enterobacterial repetitive intragenic consensus (ERIC) sequences. This study reports a high diversity of genetic patterns. Ten clusters were found for E. coli isolates and five clusters for K. pneumoniae strains by means of ERIC analysis. In conclusion, in this country, the most prevalent type is still the TEM-type, but CTX-M is growing rapidly.

Demand Response Programs Definition Using Demand Price Elasticity to Define Consumers Aggregation for an Improved Remuneration Structure

The positioning of the consumers in the power systems operation has been changed in the recent years, namely due to the implementation of competitive electricity markets. Demand response is an opportunity for the consumers’ participation in electricity markets. Smart grids can give an important support for the integration of demand response. The methodology proposed in the present paper aims to create an improved demand response program definition and remuneration scheme for aggregated resources. The consumers are aggregated in a certain number of clusters, each one corresponding to a distinct demand response program, according to the economic impact of the resulting remuneration tariff. The knowledge about the consumers is obtained from its demand price elasticity values. The illustrative case study included in the paper is based on a 218 consumers’ scenario.

Remuneration Structure Definition for Distributed Generation Units and Demand Response Participants Aggregation

The implementation of competitive electricity markets has changed the consumers’ and distributed generation position power systems operation. The use of distributed generation and the participation in demand response programs, namely in smart grids, bring several advantages for consumers, aggregators, and system operators. The present paper proposes a remuneration structure for aggregated distributed generation and demand response resources. A virtual power player aggregates all the resources. The resources are aggregated in a certain number of clusters, each one corresponding to a distinct tariff group, according to the economic impact of the resulting remuneration tariff. The determined tariffs are intended to be used for several months. The aggregator can define the periodicity of the tariffs definition. The case study in this paper includes 218 consumers, and 66 distributed generation units.

Evolution of Drug Resistance: Insight on TEM β-Lactamases Structure and Activity and β-Lactam Antibiotics

Since the discovery of the first penicillin bacterial resistance to β-lactam antibiotics has spread and evolved promoting new resistances to pathogens. The most common mechanism of resistance is the production of β-lactamases that have spread thorough nature and evolve to complex phenotypes like CMT type enzymes. New antibiotics have been introduced in clinical practice, and therefore it becomes necessary a concise summary about their molecular targets, specific use and other properties. β-lactamases are still a major medical concern and they have been extensively studied and described in the scientific literature. Several authors agree that Glu166 should be the general base and Ser70 should perform the nucleophilic attack to the carbon of the carbonyl group of the β-lactam ring. Nevertheless there still is controversy on their catalytic mechanism. TEMs evolve at incredible pace presenting more complex phenotypes due to their tolerance to mutations. These mutations lead to an increasing need of novel, stronger and more specific and stable antibiotics. The present review summarizes key structural, molecular and functional aspects of ESBL, IRT and CMT TEM β-lactamases properties and up to date diagrams of the TEM variants with defined phenotype. The activity and structural characteristics of several available TEMs in the NCBI-PDB are presented, as well as the relation of the various mutated residues and their specific properties and some previously proposed catalytic mechanisms.

Projeto de Reabilitação da EM 607 no Concelho de Valongo

Pretende-se com este trabalho fazer um estudo detalhado de um troço da Estrada Municipal 607, situado no concelho de Valongo, caracterizando o seu estado de degradação e definindo qual ou quais as soluções mais convenientes de reabilitação a adotar. O pavimento alvo deste trabalho é abrangido por três ruas pertencentes à EM 607, Rua de Vilar, Rua de Cabeda e Rua D. Pedro IV e apresenta uma extensão total de 4,8 km. Este trabalho pode ser dividido em duas partes distintas: uma primeira parte, mais do âmbito teórico, onde é feita uma abordagem histórica desde o desenvolvimento dos pavimentos rodoviários até aos métodos e pavimentos existentes na atualidade e uma segunda parte, que diz respeito ao desenvolvimento prático do trabalho, onde é feito um estudo do pavimento e são apresentadas soluções de reabilitação e respetivos dimensionamentos. Iniciou-se o estudo do pavimento com uma análise geral das patologias existentes, definindo o estado de degradação em que este se encontra. Concluiu-se que se estava na presença de um pavimento muito degradado, havendo troços com um nível de degradação muito elevado, o que proporciona desconforto na circulação dos condutores. Foi efetuado um estudo de tráfego de pesados, onde se percebeu que se tratava de um pavimento com intenso tráfego de pesados e que talvez este pavimento não esteja apto para o suportar. A retirada de carotes veio confirmar este pressuposto, pois as espessuras das camadas betuminosas mostraram ser insuficientes para o atual volume de tráfego. As soluções de reabilitação foram ao encontro de várias soluções para diferentes situações, dando aos responsáveis da Câmara Municipal de Valongo a possibilidade de optarem por aquela que melhor se ajuste às suas necessidades, bem como às suas condições financeiras. Assim, foram propostas três soluções para três capacidades de resistência e períodos de vida úteis distintos. A primeira solução engloba a remoção do pavimento existente e colocação de uma estrutura completamente nova, com três camadas betuminosas e dimensionada para o volume de tráfego atual, apresentando um período de vida útil de 20 anos, mas que é mais dispendiosa. A segunda solução apresenta apenas duas camadas betuminosas, onde seriam removidas apenas as camadas betuminosas, aproveitando a camada de sub-base. Esta solução tem um período de vida útil estimado de cerca de 8 anos. A terceira solução, com um período de vida útil de 5 anos, baseia-se na remoção parcial de uma largura da faixa de rodagem, aproveitando a restante. Na largura removida seria colocada uma estrutura de pavimento nova e dimensionada na segunda solução. Por último, foi dimensionado o sistema de drenagem transversal e longitudinal, sendo caracterizadas as linhas de águas e as respetivas bacias hidrográficas. As valetas e passagens hidráulicas existentes não estão dimensionadas para o atual escoamento de águas pluviais a que o pavimento está sujeito. As valetas são muito reduzidas, apresentando-se em alguns casos degradadas ou a necessitarem de limpeza urgente.

ARCHI-AVE: património documental da bacia do Ave: estudo orgânico-funcional e tratamento documental

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