ANTIMICROBIAL ACTIVITY of CARPOLOBIA LUTEA EXTRACTS and FRACTIONS

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Three-dimensional structure of human electron transfer flavoprotein to 2.1-Å resolution

Mammalian electron transfer flavoproteins (ETF) are heterodimers containing a single equivalent of flavin adenine dinucleotide (FAD). They function as electron shuttles between primary flavoprotein dehydrogenases involved in mitochondrial fatty acid and amino acid catabolism and the membrane-bound electron transfer flavoprotein ubiquinone oxidoreductase. The structure of human ETF solved to 2.1-Å resolution reveals that the ETF molecule is comprised of three distinct domains: two domains are contributed by the α subunit and the third domain is made up entirely by the β subunit. The N-terminal portion of the α subunit and the majority of the β subunit have identical polypeptide folds, in the absence of any sequence homology. FAD lies in a cleft between the two subunits, with most of the FAD molecule residing in the C-terminal portion of the α subunit. Alignment of all the known sequences for the ETF α subunits together with the putative FixB gene product shows that the residues directly involved in FAD binding are conserved. A hydrogen bond is formed between the N5 of the FAD isoalloxazine ring and the hydroxyl side chain of αT266, suggesting why the pathogenic mutation, αT266M, affects ETF activity in patients with glutaric acidemia type II. Hydrogen bonds between the 4′-hydroxyl of the ribityl chain of FAD and N1 of the isoalloxazine ring, and between αH286 and the C2-carbonyl oxygen of the isoalloxazine ring, may play a role in the stabilization of the anionic semiquinone. With the known structure of medium chain acyl-CoA dehydrogenase, we hypothesize a possible structure for docking the two proteins.

Mechanistic Importance of Redox Potentials and Conformational Flexibility in Electron-Transferring Flavoproteins

The mitochondrial matrix flavoproteins electron transfer flavoprotein (ETF) and electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) are responsible for linking fatty acid β-oxidation with the main mitochondrial respiratory chain. Electrons derived from flavoprotein dehydrogenases are transferred sequentially through ETF and ETF-QO to ubiquinone and then into the respiratory chain via complex III. In this study, the effects of changes in ETF-QO redox potentials on its activity and the conformational flexibility of ETF were investigated. ETF-QO contains one [4Fe-4S]2+,1+ and one flavin adenine dinucleotide (FAD). In the porcine protein, threonine 367 is hydrogen bonded to N1 and O2 of the flavin ring of the FAD. The analogous site in Rhodobacter sphaeroides ETF-QO is asparagine 338. Mutations N338T and N338A were introduced into the R. sphaeroides protein by site-directed mutagenesis to determine the impact of hydrogen bonding at this site on redox potentials and activity. FAD redox potentials were measured by potentiometric titration probed by electron paramagnetic resonance (EPR) spectroscopy. The N338T and N338A mutations lowered the midpoint potentials, which resulted in a decrease in the quinone reductase activity and negligible impact on disproportionation of ETF1e- catalyzed by ETF-QO. These observations indicate that the FAD is involved in electron transfer to ubiquinone, but not in electron transfer from ETF to ETF-QO. Therefore it is proposed that the iron-sulfur cluster is the immediate acceptor from ETF. It has been proposed that the αII domain of ETF is mobile, allowing promiscuous interactions with structurally different partners. Double electron-electron resonance (DEER) was used to measure the distance between spin labels at various sites and an enzymatically reduced FAD cofactor in Paracoccus denitrificans ETF. Two or three interspin distance distributions were observed for spin-labels in the αI (A43C) and βIII (A111C) domains, but only one is observed for a label in the βII (A210C) domain. This suggests that the αII domain adopts several stable conformations which may correspond to a closed/inactive conformation and an open/active conformation. An additional mutation, E162A, was introduced to increase the mobility of the αII domain. The E162A mutation doubled the activity compared to wild-type and caused the distance distributions to become wider. The DEER method has the potential to characterize conformational changes in ETF that occur when it interacts with various redox partners.

Is video-case an efficient tool to complement the practical learning in real contexts? Effects on satisfaction and performance in Social Work Degree students

Este documento es un artículo inédito que ha sido aceptado para su publicación. Como un servicio a sus autores y lectores, Alternativas. Cuadernos de trabajo social proporciona online esta edición preliminar. El manuscrito puede sufrir alteraciones tras la edición y corrección de pruebas, antes de su publicación definitiva. Los posibles cambios no afectarán en ningún caso a la información contenida en esta hoja, ni a lo esencial del contenido del artículo.

The adverse selection component of exchange traded funds

The aim of our paper is to examine whether Exchange Traded Funds (ETFs) diversify away the private information of informed traders. We apply the spread decomposition models of Glosten and Harris (1998) and Madhavan, Richardson and Roomans (1997) to a sample of ETFs and their control securities. Our results indicate that ETFs have significantly lower adverse selection costs than their control securities. This suggests that private information is diversified away for these securities. Our results therefore offer one explanation for the rapid growth in the ETF market.

Exchange-traded funds and information asymmetry

This thesis focuses on three main questions. The first uses ExchangeTraded Funds (ETFs) to evaluate estimated adverse selection costs obtained spread decomposition models. The second compares the Probability of Informed Trading (PIN) in Exchange-Traded Funds to control securities. The third examines the intra-day ETF trading patterns. These spread decomposition models evaluated are Glosten and Harris (1988); George, Kaul, and Nimalendran (1991); Lin, Sanger, and Booth (1995); Madhavan, Richardson, and Roomans (1997); Huang and Stoll (1997). Using the characteristics of ETFs it is shown that only the Glosten and Harris (1988) and Madhavan, et al (1997) models provide theoretically consistent results. When the PIN measure is employed ETFs are shown to have greater PINs than control securities. The investigation of the intra-day trading patterns shows that return volatility and trading volume have a U-shaped intra-day pattern. A study of trading systems shows that ETFs on the American Stock Exchange (AMEX) have a U-shaped intra-day pattern of bid-ask spreads, while ETFs on NASDAQ do not. Specifically, ETFs on NASDAQ have higher bid-ask spreads at the market opening, then the lowest bid-ask spread in the middle of the day. At the close of the market, the bid-ask spread of ETFs on NASDAQ slightly elevated when compared to mid-day.

Intraday trading patterns in London listed exchange traded funds

In this paper we examine the intraday trading patterns of Exchange Traded Funds (ETFs) listed on the London Stock Exchange. ETFs have been shown to be characterised by much lower bid–ask spread costs and by lower levels of information asymmetry than individual securities. One possible explanation for intraday trading patterns is that concentration of trading arises at the start of the trading day because informed traders have private information that quickly diminishes in value as trading progresses. Since ETFs have lower trading costs and lower levels of information asymmetry we would expect these securities to display less pronounced intraday patterns than individual securities. We fail to find that ETFs are characterised by concentrated trading bouts during the day and therefore find support for the argument that information asymmetry is the cause of intraday volume patterns in stock markets. We find that ETF bid–ask spreads and volatility are elevated at the open but not at the close. This lends support to the “accumulation of information” explanation that sees high spreads and volatility at the open as a consequence of information accumulating during a market closure and impacting on the market when it next opens.

Evaluating spread models with a basket security

In this article we evaluate the most widely used spread decomposition models using Exchange Traded Funds (ETFs). These funds are an example of a basket security and allow the diversification of private information causing these securities to have lower adverse selection costs than individual securities. We use this feature as a criterion for evaluating spread decomposition models. Comparisons of adverse selection costs for ETF's and control securities obtained from spread decomposition models show that only the Glosten-Harris (1988) and the Madhavan-Richardson-Roomans (1997) models provide estimates of the spread that are consistent with the diversification of private information in a basket security. Our results are robust even after controlling for the stock exchange. © 2011 Copyright Taylor and Francis Group, LLC.

Three essays on the microstructure of exchange traded funds

Exchange traded funds (ETFs) have increased significantly in popularity since they were first introduced in 1993. However, there is still much that is unknown about ETFs in the extant literature. This dissertation attempts to fill gaps in the ETF literature by using three related essays. In these three essays, we compare ETFs to closed ended mutual funds (CEFs) by decomposing the bid-ask spread into its three components; we look at the intraday shape of ETFs and compare it to the intraday shape of equities as well as examine the co-integration factor between ETFs on the London Stock Exchange and the New York Stock Exchange; we also examine the differences between leveraged ETFs and unleveraged ETFs by analyzing the impact of liquidity and volatility. These three essays are presented in Chapters 1, 2, and 3, respectively. ^ Chapter one uses the Huang and Stoll (1997) model to decompose the bid-ask spread in CEFs and ETFs for two distinct periods—a normal and a volatile period. We show a higher adverse selection component for CEFs than for ETFs without regard to volatility. However, both ETFs and CEFs increased in magnitude of the adverse selection component in the period of high volatility. Chapter two uses a mix of the Werner and Kleidon (1993) and the Hupperets and Menkveld (2002) methods to get the intraday shape of ETFs and analyze co-integration between London and New York trading. We find two different shapes for New York and London ETFs. There also appears to be evidence of co-integration in the overlapping two-hour trading period but not over the entire trading day for the two locations. The third chapter discusses the new class of ETFs called leveraged ETFs. We examine the liquidity and depth differences between unleveraged and leveraged ETFs at the aggregate level and when the leveraged ETFs are classified by the leveraged multiples of -3, -2, -1, 2, and 3, both for a normal and a volatile period. We find distinct differences between leveraged and unleveraged ETFs at the aggregate level, with leveraged ETFs having larger spreads than unleveraged ETFs. Furthermore, while both leveraged and unleveraged ETFs have larger spreads in high volatility, for the leveraged ETFs the change in magnitude is significantly larger than for the unleveraged ETFs. Among the multiples, the -2 leveraged ETF is the most pronounced in its liquidity characteristics, more so in volatile times. ^

Avaliação multidimensional da qualidade de vida em idosos: um estudo no Curimataú ocidental paraibano

The fast growth of the elderly population is a reality throughout the world and has become one of the greatest challenges for contemporary public health. When considering the increased life expectancy and the aging as a multidimensional phenomenon, one should highlight the need to investigate if the increase of longevity is associated with satisfactory levels of Quality of Life (QOL). This study has the objective of assessing the QOL of elderly people from the Paraíba’s Western Curimataú microregion, explained by its health and living conditions. This is a cross-sectional and observational study with quantitative design held with 444 elderly people from five cities: Barra de Santa Rosa, Cuité, Nova Floresta, Remígio e Sossego. In order to obtain information, the following instruments were used: I) Questionnaire for collection data related to the elderly population, for sociodemographic, clinical and behavioral characteristics; and II) WHOQOL-Old questionnaire, with a view to measuring and assessing QOL. Data were processed on the IBM-SPSS Statistics 20.0 software by means of the ANOVA (one-way), Student’s t, Mann-Whitney, Kruskal-Wallis and Pearson’s correlation tests, with p-values<0,05 accepted as being statistically significant. The results indicate a good global QOL (ETT=65,69%), with better assessment by elderly men, aged between 60 and 74 years, married, living with partner and children, without caregiver, physical activity practitioners, with up to one health problem before an aspect of multimorbidity and with very good and/or good assessment of basic needs. The self-reported stress showed a negative significant correlation before the global QOL, where the greater the perception of stress, the worse the assessment of QOL. In the faceted assessment of QOL, the Sensory Operation showed the best performance (ETF= 68,86%) and the Social Participation (SP) the worst (ETF=60,37%). In the multiple linear regression model, SP is singly responsible for 51,8% (R2=0,518) of explanation of the global QOL. In the intercorrelation among the WHOQOL-Old facets, only Death and Dying did not reveal significance. The harmony highlighted among the facets raises the need to ensure a comprehensive health care for the elderly population, especially in understanding the social participation as an intrinsic part of the QOL and that it requires the re-discussion and reconstruction of individual and collective, family and community, political and government actions. Hence, guaranteeing an active, healthy and participatory aging, with QOL, is the major challenge.

Avaliação multidimensional da qualidade de vida em idosos: um estudo no Curimataú ocidental paraibano

The fast growth of the elderly population is a reality throughout the world and has become one of the greatest challenges for contemporary public health. When considering the increased life expectancy and the aging as a multidimensional phenomenon, one should highlight the need to investigate if the increase of longevity is associated with satisfactory levels of Quality of Life (QOL). This study has the objective of assessing the QOL of elderly people from the Paraíba’s Western Curimataú microregion, explained by its health and living conditions. This is a cross-sectional and observational study with quantitative design held with 444 elderly people from five cities: Barra de Santa Rosa, Cuité, Nova Floresta, Remígio e Sossego. In order to obtain information, the following instruments were used: I) Questionnaire for collection data related to the elderly population, for sociodemographic, clinical and behavioral characteristics; and II) WHOQOL-Old questionnaire, with a view to measuring and assessing QOL. Data were processed on the IBM-SPSS Statistics 20.0 software by means of the ANOVA (one-way), Student’s t, Mann-Whitney, Kruskal-Wallis and Pearson’s correlation tests, with p-values<0,05 accepted as being statistically significant. The results indicate a good global QOL (ETT=65,69%), with better assessment by elderly men, aged between 60 and 74 years, married, living with partner and children, without caregiver, physical activity practitioners, with up to one health problem before an aspect of multimorbidity and with very good and/or good assessment of basic needs. The self-reported stress showed a negative significant correlation before the global QOL, where the greater the perception of stress, the worse the assessment of QOL. In the faceted assessment of QOL, the Sensory Operation showed the best performance (ETF= 68,86%) and the Social Participation (SP) the worst (ETF=60,37%). In the multiple linear regression model, SP is singly responsible for 51,8% (R2=0,518) of explanation of the global QOL. In the intercorrelation among the WHOQOL-Old facets, only Death and Dying did not reveal significance. The harmony highlighted among the facets raises the need to ensure a comprehensive health care for the elderly population, especially in understanding the social participation as an intrinsic part of the QOL and that it requires the re-discussion and reconstruction of individual and collective, family and community, political and government actions. Hence, guaranteeing an active, healthy and participatory aging, with QOL, is the major challenge.

Microstructure Characteristics of U.S. Futures Markets

Prior finance literature lacks a comprehensive analysis of microstructure characteristics of U.S. futures markets due to the lack of data availability. Utilizing a unique data set for five different futures contract this dissertation fills this gap in the finance literature. In three essays price discovery, resiliency and the components of bid-ask spreads in electronic futures markets are examined. In order to provide comprehensive and robust analysis, both moderately volatile pre-crisis and volatile crisis periods are included in the analysis. The first essay entitled “Price Discovery and Liquidity Characteristics for U.S. Electronic Futures and ETF Markets” explores the price discovery process in U.S. futures and ETF markets. Hasbrouck’s information share method is applied to futures and ETF instruments. The information share results show that futures markets dominate the price discovery process. The results on the factors that affect the price discovery process show that when volatility increases, the price leadership of futures markets declines. Furthermore, when the relative size of bid-ask spread in one market increases, its information share decreases. The second essay, entitled “The Resiliency of Large Trades for U.S. Electronic Futures Markets,“ examines the effects of large trades in futures markets. How quickly prices and liquidity recovers after large trades is an important characteristic of financial markets. The price effects of large trades are greater during the crisis period compared to the pre-crisis period. Furthermore, relative to the pre-crisis period, during the crisis period it takes more trades until liquidity returns to the pre-block trade levels. The third essay, entitled “Components of Quoted Bid-Ask Spreads in U.S. Electronic Futures Markets,” investigates the bid-ask spread components in futures market. The components of bid-ask spreads is one of the most important subjects of microstructure studies. Utilizing Huang and Stoll’s (1997) method the third essay of this dissertation provides the first analysis of the components of quoted bid-ask spreads in U.S. electronic futures markets. The results show that order processing cost is the largest component of bid-ask spreads, followed by inventory holding costs. During the crisis period market makers increase bid-ask spreads due to increasing inventory holding and adverse selection risks.

Le “brigand lusitanien” reconsidéré. Analyse du problème de la terre chez Appien

L’étude du “brigandage lusitanien” a donné lieu à une importante activité de recherche depuis la fin du XIXe siècle. Pour autant, et malgré une inflexion progressive de l’historiographie moderne vers une approche plus nuancée de l’origine du phénomène, le problème de la terre reste encore aujourd’hui au centre des préoccupations de nombre d’historiens et archéologiques. À partir d’une discussion serrée des principaux passages de Tite-Live, Diodore et surtout Appien, relatifs à la relation que d’aucuns ont voulu établir entre manque et/ou pauvreté de la terre et développement du brigandage chez les Lusitaniens, il est proposé une critique de l’interprétation socio-économique.