Showing papers by "Federal University of Rio de Janeiro published in 2005"

Origin of the cataclysmic Late Heavy Bombardment period of the terrestrial planets

Abstract: The petrology record on the Moon suggests that a cataclysmic spike in the cratering rate occurred approximately 700 million years after the planets formed; this event is known as the Late Heavy Bombardment (LHB). Planetary formation theories cannot naturally account for an intense period of planetesimal bombardment so late in Solar System history. Several models have been proposed to explain a late impact spike, but none of them has been set within a self-consistent framework of Solar System evolution. Here we propose that the LHB was triggered by the rapid migration of the giant planets, which occurred after a long quiescent period. During this burst of migration, the planetesimal disk outside the orbits of the planets was destabilized, causing a sudden massive delivery of planetesimals to the inner Solar System. The asteroid belt was also strongly perturbed, with these objects supplying a significant fraction of the LHB impactors in accordance with recent geochemical evidence. Our model not only naturally explains the LHB, but also reproduces the observational constraints of the outer Solar System.

Origin of the orbital architecture of the giant planets of the Solar System.

Abstract: A collection of three papers in this issue, tackling seemingly unrelated planetary phenomena, marks a notable unification of Solar System dynamics. The three problems covered are the hard-to-explain orbits of giant planets, the evolution of the orbits of Jupiter's Trojan asteroids, and the cause of the ‘Late Heavy Bombardment’ that peppered the Moon with meteors, comets and asteroids some 700 million years after the planets were formed. Key to all these events, on this new model, was a rapid migration of the giant planets (Saturn, Jupiter, Neptune and Uranus) after a long period of stability within the Solar System. Planetary formation theories1,2 suggest that the giant planets formed on circular and coplanar orbits. The eccentricities of Jupiter, Saturn and Uranus, however, reach values of 6 per cent, 9 per cent and 8 per cent, respectively. In addition, the inclinations of the orbital planes of Saturn, Uranus and Neptune take maximum values of ∼2 degrees with respect to the mean orbital plane of Jupiter. Existing models for the excitation of the eccentricity of extrasolar giant planets3,4,5 have not been successfully applied to the Solar System. Here we show that a planetary system with initial quasi-circular, coplanar orbits would have evolved to the current orbital configuration, provided that Jupiter and Saturn crossed their 1:2 orbital resonance. We show that this resonance crossing could have occurred as the giant planets migrated owing to their interaction with a disk of planetesimals6,7. Our model reproduces all the important characteristics of the giant planets' orbits, namely their final semimajor axes, eccentricities and mutual inclinations.

Global distribution of rotavirus serotypes/genotypes and its implication for the development and implementation of an effective rotavirus vaccine.

Abstract: A safe and effective rotavirus vaccine is urgently needed, particularly in developing countries. Critical to vaccine development and implementation is a knowledge base concerning the epidemiology of rotavirus G and P serotypes/genotypes throughout the world. The temporal and geographical distribution of human rotavirus G and P types was reviewed by analysing a total of 45571 strains collected globally from 124 studies reported from 52 countries on five continents published between 1989 and 2004. Four common G types (G1, G2, G3 and G4) in conjunction with P[8] or P[4] represented over 88% of the strains analysed worldwide. In addition, serotype G9 viruses associated with P[8] or P[6] were shown to have emerged as the fourth globally important G type with the relative frequency of 4.1%. When the global G and/or P type distributions were divided into five continents/subcontinents, several characteristic features emerged. For example, the P[8]G1 represented over 70% of rotavirus infections in North America, Europe and Australia, but only about 30% of the infections in South America and Asia, and 23% in Africa. In addition, in Africa (i) the relative frequency of G8 was as high as that of the globally common G3 or G4, (ii) P[6] represented almost one-third of all P types identified and (iii) 27% of the infections were associated with rotavirus strains bearing unusual combinations such as P[6]G8 or P[4]G8. Furthermore, in South America, uncommon G5 virus appeared to increase its epidemiological importance among children with diarrhea. Such findings have (i) confirmed the importance of continued active rotavirus strain surveillance in a variety of geographical settings and (ii) provided important considerations for the development and implementation of an effective rotavirus vaccine (e.g. a geographical P-G type adjustment in the formulation of next generation multivalent vaccines).

Staphylococcus aureus Endocarditis A Consequence of Medical Progress

Abstract: ContextThe global significance of infective endocarditis (IE) caused by Staphylococcus aureus is unknown.ObjectivesTo document the international emergence of health care–associated S aureus IE and methicillin-resistant S aureus (MRSA) IE and to evaluate regional variation in patients with S aureus IE.Design, Setting, and ParticipantsProspective observational cohort study set in 39 medical centers in 16 countries. Participants were a population of 1779 patients with definite IE as defined by Duke criteria who were enrolled in the International Collaboration on Endocarditis-Prospective Cohort Study from June 2000 to December 2003.Main Outcome MeasureIn-hospital mortality.ResultsS aureus was the most common pathogen among the 1779 cases of definite IE in the International Collaboration on Endocarditis Prospective-Cohort Study (558 patients, 31.4%). Health care−associated infection was the most common form of S aureus IE (218 patients, 39.1%), accounting for 25.9% (Australia/New Zealand) to 54.2% (Brazil) of cases. Most patients with health care−associated S aureus IE (131 patients, 60.1%) acquired the infection outside of the hospital. MRSA IE was more common in the United States (37.2%) and Brazil (37.5%) than in Europe/Middle East (23.7%) and Australia/New Zealand (15.5%, P<.001). Persistent bacteremia was independently associated with MRSA IE (odds ratio, 6.2; 95% confidence interval, 2.9-13.2). Patients in the United States were most likely to be hemodialysis dependent, to have diabetes, to have a presumed intravascular device source, to receive vancomycin, to be infected with MRSA, and to have persistent bacteremia (P<.001 for all comparisons).ConclusionsS aureus is the leading cause of IE in many regions of the world. Characteristics of patients with S aureus IE vary significantly by region. Further studies are required to determine the causes of regional variation.

Chaotic capture of Jupiter's Trojan asteroids in the early Solar System.

Abstract: A collection of three papers in this issue, tackling seemingly unrelated planetary phenomena, marks a notable unification of Solar System dynamics. The three problems covered are the hard-to-explain orbits of giant planets, the evolution of the orbits of Jupiter's Trojan asteroids, and the cause of the ‘Late Heavy Bombardment’ that peppered the Moon with meteors, comets and asteroids some 700 million years after the planets were formed. Key to all these events, on this new model, was a rapid migration of the giant planets (Saturn, Jupiter, Neptune and Uranus) after a long period of stability within the Solar System. Jupiter's Trojans are asteroids that follow essentially the same orbit as Jupiter, but lead or trail the planet by an angular distance of ∼60 degrees (co-orbital motion). They are hypothesized to be planetesimals that formed near Jupiter and were captured onto their current orbits while Jupiter was growing1,2, possibly with the help of gas drag3,4,5,6 and/or collisions7. This idea, however, cannot explain some basic properties of the Trojan population, in particular its broad orbital inclination distribution, which ranges up to ∼40 degrees (ref. 8). Here we show that the Trojans could have formed in more distant regions and been subsequently captured into co-orbital motion with Jupiter during the time when the giant planets migrated by removing neighbouring planetesimals9,10,11,12. The capture was possible during a short period of time, just after Jupiter and Saturn crossed their mutual 1:2 resonance, when the dynamics of the Trojan region were completely chaotic. Our simulations of this process satisfactorily reproduce the orbital distribution of the Trojans and their total mass.

Sacrificial bonds and hidden length dissipate energy as mineralized fibrils separate during bone fracture.

Abstract: Properties of the organic matrix of bone as well as its function in the microstructure could be the key to the remarkable mechanical properties of bone. Previously, it was found that on the molecular level, calcium-mediated sacrificial bonds increased stiffness and enhanced energy dissipation in bone constituent molecules. Here we present evidence for how this sacrificial bond and hidden length mechanism contributes to the mechanical properties of the bone composite, by investigating the nanoscale arrangement of the bone constituents and their interactions. We find evidence that bone consists of mineralized collagen fibrils and a non-fibrillar organic matrix, which acts as a 'glue' that holds the mineralized fibrils together. We believe that this glue may resist the separation of mineralized collagen fibrils. As in the case of the sacrificial bonds in single molecules, the effectiveness of this mechanism increases with the presence of Ca2+ ions.

Biodiesel: an overview

Abstract: The importance of biodiesel production was analyzed based on scientific articles and patents. A critical analysis was presented on the most used oil sources, the catalysts and the methods to verify the transesterification yields. Also analyzed were the comparative studies on emissions from pure fossil diesel and mixtures with biodiesel in variable proportions. Finally some challenges and considerations focused on technological, agronomic and infrastructure aspects of biodiesel production were indicated.

Bioisosterism: a useful strategy for molecular modification and drug design.

Abstract: This review aim to demonstrate the role of bioisosterism in rational drug design as well as in the molecular modification and optimization process aiming to improve pharmacodynamic and pharmacokinetic properties of lead compounds. Bioisosterism is a strategy of Medicinal Chemistry for the rational design of new drugs, applied with a lead compound (LC) as a special process of molecular modification (1). The LC should be of a completely well known chemical structure and possess an equally well known mechanism of action, if possible at the level of topographic interaction with the receptor, including knowledge of all of its pharmacophoric group. Furthermore, the pathways of metabolic inactivation (2), as well as the main determining structural factors of the physicochemical properties which regulate the bioavailability, and its side effects, whether directly or not, should be known so as to allow for a broad prediction of the definition of the bioisosteric relation to be used. The success of this strategy in developing new substances which are therapeutically attractive has observed a significant growth in distinct therapeutic classes, being amply used by the pharmaceutical industry to discover new analogs of therapeutic innovations commercially attractive (me-too), and also as a tool useful in the molecular modification. There may be innumerous reasons for the use of bioisosterism to design new drugs, including the necessity to improve pharmacological activity, gain selectivity for a determined receptor or enzymatic isoform subtype - with simultaneous reduction of certain adverse effects -, or even optimize the pharmacokinetics the LC might present. In this paper, we will discuss bioisosterism as a strategy of molecular modification, showing its importance in building a new series of congeners compounds designed as candidate of new drugs, giving examples of successful cases in distinct therapeutic classes (3-7).

Incidence and prognosis of intraabdominal hypertension in a mixed population of critically ill patients: a multiple-center epidemiological study.

Abstract: Objective: Intraabdominal hypertension is associated with significant morbidity and mortality in surgical and trauma patients. The aim of this study was to assess, in a mixed population of critically ill patients, whether intraabdominal pressure at admission was an independent predictor for mortality and to evaluate the effects of intraabdominal hypertension on organ functions. Design: Multiple-center, prospective epidemiologic study. Setting: Fourteen intensive care units in six countries. Patients: A total of 265 consecutive patients admitted for >24 hrs during the 4-wk study period. Interventions: None. Measurements and Main Results: Intraabdominal pressure was measured twice daily via the bladder. Data recorded on admission were the patient demographics with Simplified Acute Physiology Score II, Acute Physiology and Chronic Health Evaluation II score, and type of admission; during intensive care stay, Sepsis-Related Organ Failure Assessment score and intraabdominal pressure were measured daily together with fluid balance. Nonsurvivors had a significantly higher mean intraabdominal pressure on admission than survivors: 11.4 4.8 vs. 9.5 4.8 mm Hg. Independent predictors for mortality were age (odds ratio, 1.04; 95% confidence interval, 1.01‐1.06; p .003), Acute Physiology and Chronic Health Evaluation II score (odds ratio, 1.1; 95% confidence interval, 1.05‐1.15; p < .0001), type of intensive care unit admission (odds ratio, 2.5 medical vs. surgical; 95% confidence interval, 1.24‐5.16; p .01), and the presence of liver dysfunction (odds ratio, 2.5; 95% confidence interval, 1.06‐5.8; p .04). The occurrence of intraabdominal hypertension during the intensive care unit stay was also an independent predictor of mortality (relative risk, 1.85; 95% confidence interval, 1.12‐3.06; p .01). Patients with intraabdominal hypertension at admission had significantly higher Sepsis-Related Organ Failure Assessment scores during the intensive care unit stay than patients without intraabdominal hypertension. Conclusions: Intraabdominal hypertension on admission was associated with severe organ dysfunction during the intensive care unit stay. The mean intraabdominal pressure on admission was not an independent risk factor for mortality; however, the occurrence of intraabdominal hypertension during the intensive care unit stay was an independent outcome predictor. (Crit Care Med 2005; 33:315‐322)

Disponibilidade domiciliar de alimentos no Brasil: distribuição e evolução (1974-2003)

Abstract: OBJETIVO: Descrever a distribuicao da disponibilidade domiciliar de alimentos no Brasil em 2002-2003 e avaliar sua evolucao nas areas metropolitanas do Pais no periodo 1974-2003. METODOS: A principal base de dados do estudo e a Pesquisa de Orcamento Familiar de 2002-2003 realizada pelo Instituto Brasileiro de Geografia e Estatistica em 48.470 domicilios brasileiros. Em cada domicilio, num periodo de sete dias consecutivos, foram registradas todas as aquisicoes, monetarias ou nao monetarias, de alimentos e bebidas para consumo familiar. As quantidades de alimentos adquiridas foram transformadas em calorias e macronutrientes, usando tabelas de composicao alimentar. RESULTADOS: Caracteristicas positivas do padrao alimentar, encontradas em todas as regioes e em todas as classes de rendimento, foram a adequacao do teor proteico das dietas e o elevado aporte relativo de proteinas de alto valor biologico. Caracteristicas negativas, tambem disseminadas no Pais, foram excesso de acucar e presenca insuficiente de frutas e hortalicas na dieta. Nas regioes economicamente mais desenvolvidas, no meio urbano e entre familias com maior rendimento houve tambem excesso de gorduras em geral e de gorduras saturadas. A evolucao nas areas metropolitanas do Pais evidenciou declinio no consumo de alimentos basicos, como arroz e feijao, aumentos de ate 400% no consumo de produtos industrializados, como biscoitos e refrigerantes, persistencia do consumo excessivo de acucar e insuficiente de frutas e hortalicas e aumento no teor da dieta em gorduras em geral e gorduras saturadas. CONCLUSOES: Padroes e tendencias da disponibilidade domiciliar de alimentos no Brasil sao consistentes com a importância crescente de doencas cronicas nao transmissiveis no perfil de morbi-mortalidade e com o aumento continuo da prevalencia da obesidade no Pais.

Plantas medicinais: cura segura?

Abstract: This paper reviews the recent literature on synergism, adulteration and risks of using medicinal plants. The use of copaiba and sacaca plants as well as their adulteration and side effects, are also described. In addition, the new regulations on phytotherapeutic registration in Brazil and Europe are discussed.

Isotropic Fractionator: A Simple, Rapid Method for the Quantification of Total Cell and Neuron Numbers in the Brain

Abstract: Stereological techniques that estimate cell numbers must be restricted to well defined structures of isotropic architecture and therefore do not apply to the whole brain or to large neural regions. We developed a novel, fast, and inexpensive method to quantify total numbers of neuronal and non-neuronal cells in the brain or any dissectable regions thereof. It consists of transforming highly anisotropic brain structures into homogeneous, isotropic suspensions of cell nuclei, which can be counted and identified immunocytochemically as neuronal or non-neuronal. Estimates of total cell, neuronal, and non-neuronal numbers can be obtained in 24 h and vary by <10% among animals. Because the estimates obtained are independent of brain volume, they can be used in comparative studies of brain-volume variation among species and in studies of phylogenesis, development, adult neurogenesis, and pathology. Applying this method to the adult rat brain, we show, for example, that it contains ∼330 million cells, of which 200 million are neurons, and almost 70% of these are located in the cerebellum alone. Moreover, contrary to what is commonly assumed in the literature, we show that glial cells are not the majority in the rat brain.

The environmentalism of the poor - a study of ecological conflicts and valuation

Abstract: No entanto, uma das caracteristicas mais notaveis da atuacao de Alier e que suas atividades cientificas e academicas nunca sobrepujaram o compromisso politico-humanista e o exercicio de uma cidadania ativa, preocupada com os pobres. Uma atitude bastante significativa nesses tempos de cinismo e indiferenca crescentes nos meios intelectuais. Nesse sentido, as analises teoricas de Alier sobre economia dos recursos naturais sao marcadas por decadas de convivio com pescadores, camponeses, pequenos extrativistas e outros moradores das zonas rurais da America Latina, Asia e Africa. Sao individuos que sofrem, de modo particularmente acentuado, os efeitos da degradacao ambiental – ate mesmo pela dependencia direta dos fatores climaticos e ciclicos da natureza – sem participar da festa do consumismo que em grande parte provoca a atual crise ecologica global.

Effect of roasting on the formation of chlorogenic acid lactones in coffee.

Abstract: Of all plant constituents, coffee has one of the highest concentrations of chlorogenic acids. When roasting coffee, some of these are transformed into chlorogenic acid lactones (CGL). We have studied the formation of CGL during the roasting of coffee beans in Coffea arabica cv. Bourbon; C. arabicacv. Longberry; and C. canephora cv. Robusta. Individual CGL levels were determined by comparison of HPLC peaks with those of synthetic CGL standards. Seven CGL were identified: 3-caffeoylquinic-1,5-lactone (3-CQL), 4- caffeoylquinic-1,5-lactone (4-CQL), 3-coumaroylquinic-1,5-lactone (3-pCoQL), 4-coumaroylquinic-1,5-lactone (4-pCoQL), 3-feruloylquinic-1,5-lactone (3-FQL), 4-feruloylquinic-1,5-lactone (4-FQL), and 3,4-dicaffeoylquinic-1,5-lactone (3,4-diCQL). 3-CQL was the most abundant lactone in C. arabica and C. canephora, reaching peak values of 230 +/- 9 and 254 +/- 4 mg/100 g (dry weight), respectively, at light medium roast ( approximately 14% weight loss). 4-CQL was the second most abundant lactone (116 +/- 3 and 139 +/- 2 mg/100 g, respectively. The maximum amount of CGL represents approximately 30% of the available precursors. The relative levels of 3-CQL and 4-CQL in roasted coffee were reverse to those of their precursors in green coffee. This suggests that roasting causes isomerization of chlorogenic acids prior to the formation of lactones and that the levels of lactones in roasted coffee do not reflect the levels of precursors in green coffee.

Acidocalcisomes ? conserved from bacteria to man

Abstract: Recent work has shown that acidocalcisomes, which are electron-dense acidic organelles rich in calcium and polyphosphate, are the only organelles that have been conserved during evolution from prokaryotes to eukaryotes Acidocalcisomes were first described in trypanosomatids and have been characterized in most detail in these species Acidocalcisomes have been linked with several functions, including storage of cations and phosphorus, polyphosphate metabolism, calcium homeostasis, maintenance of intracellular pH homeostasis and osmoregulation Here, we review acidocalcisome ultrastructure, composition and function in different trypanosomatids and other organisms

Emerging Fungal Diseases

Abstract: The epidemiology of invasive fungal infection is evolving. Yeasts other than Candida albicans and molds other than Aspergillus fumigatus have emerged as significant causes of invasive mycoses in severely immunocompromised patients. Although, in some instances, these changes may be related to medical interventions, such as the use of antifungal agents in prophylaxis, in the majority of cases, they seem to be a consequence of changes in the host, such as more-severe immunosuppression or different types of immunosuppression impacting both risk periods and the infections that occur. These factors have altered the epidemiology of infection in organ transplant recipients, premature newborns, and critically ill patients. This review discusses the epidemiology of some fungal infections that have emerged in the past few years, with an emphasis on the potential factors associated with their emergence and on practical implications of these epidemiological changes.

Technical error of measurement in anthropometry

Abstract: The anthropometrical measurements have been widely utilized to follow children's development, in the verification of the adaptations to the physical training in the athletes' selection, in studies of ethnic characterization, among others. The control of the precision and accuracy of the measurements will result in more reliable data. The objective of the present study was to diffuse the strategies to compute the technical error of measurement (TEM) according to Kevin Norton's and Tim Olds methodology (2000) and to analyze the laboratory' trainees performance. Three beginner observers (anthropometrists) of the Exercise Physiology Laboratory (Labofise) of the University of Brazil were analyzed. They accomplished measures of skin folds thickness (Cescorf, 0.1 mm) in nine different anthropometric points in 35 volunteers (25.45 ± 9.96 years). To accomplish the measures the International Society for Advancement in Kinanthropometry (ISAK) was adopted. For the TEM intra-evaluator verification, the measures were accomplished in the same volunteers in two different days and, to obtain the inter-observers TEM, the measures were accomplished in a same group of volunteers, in the same day by the three evaluators. The results indicated not acceptable TEMs only for two evaluators in the intra-evaluator analysis. The other TEMs reached acceptable results. Not acceptable TEMs demonstrated the need of technical training of evaluators in order to minimize the variability verified.

Catalogue of the Cerambycidae (Coleoptera) of the Neotropical Region. Part II. Subfamily Lamiinae

Abstract: A catalogue of the subfamily Lamiinae (Coleoptera: Cerambycidae) of the Neotropical region is presented. The tribes (36), genera (723), species (4231) and subspecies (60) are listed in alphabetical order. Under each family-group name bibliographical references are given and under each species-group name, data on the type-locality, the acronym of the institution where the type is deposited, the geographical distribution and detailed bibliographical references are provided. Two new combinations are proposed: Urographis eucharis (Bates, 1885), new comb. and Urographis vexillaris (Bates, 1872) new comb., both from Graphisurus LeConte, 1852, not Kirby, 1837. The following new names are given: Alcathousiella new name to replace Alcathous Thomson, 1864, preoccupied by Alcathous Stal, 1863, Hemiptera; Camposiellina new name to replace Camposiella Lane, 1972, preoccupied by Camposiella Hebard, 1924, Orthoptera; Edechthistatus new name to replace Parechthistatus Giesbert, 2001, preoccupied by Parechthistatus Breuning, 1942, Coleoptera; Elytracanthina new name to replace Elytracantha Lane, 1955, preoccupied by Elytracantha Kleine, 1915, Coleoptera; Eranina new name to replace Erana Bates, 1866, preoccupied by Erana Gray, 1840, Aves; Heteresmia new name to replace Esmia Pascoe, 1859, preoccupied by Esmia Leach, 1847, Mollusca; Eupalessa new name to replace Eupales Dillon & Dillon, 1945, preoccupied by Eupales Lefevre, 1885, Coleoptera; Melzerus new name to replace Idiomerus Melzer, 1934, preoccupied by Idiomerus Imms, 1912, Collembola; Midamiella new name to replace Midamus Dillon & Dillon, 1945, preoccupied by Midamus Simon, 1881, Arachnida; Neoamphion new name to replace Amphion Reiche, 1840, preoccupied by Amphion Huebner, 1819, Lepidoptera; Neocolobura new name to replace Colobura Blanchard, 1851, preoccupied by Colobura Billberg, 1820, Lepidoptera; Neohoplonotus new name to replace Hoplonotus Blanchard, 1851, preoccupied by Hoplonotus Schmidt-Goebel, 1846, Coleoptera; Neohylus new name to replace Hylus Dillon & Dillon, 1945, preocuppied by Hylus Van Dyke, 1945, Coleoptera; Neolampedusa new name to replace Lampedusa Dillon & Dillon, 1945, preoccupied by Lampedusa Boettger, 1877, Mollusca; Proseriphus new name to replace Seriphus Bates, 1864, preoccupied by Seriphus Ayres, 1857, Pisces. One new synonym is proposed: Proxepectasis Monne & Giesbert, 1992 = Parepectasoides Breuning, 1979.

An evaluation of methods for extraction and quantification of protein from marine macro- and microalgae

Abstract: Comparison of data of protein content in algae is very difficult, primarily due to differences in the analytical methods employed. The different extraction procedures (exposure to water, grinding, etc.), protein precipitation using different amounts of 25% trichloroacetic acid and quantification of protein by two different methods and using two protein standards were evaluated. All procedures were tested using freeze-dried samples of three macroalgae: Porphyra acanthophora var. acanthophora, Sargassum vulgare and Ulva fasciata. Based on these results, a protocol for protein extraction was developed, involving the immersion of samples in 4.0 mL ultra-pure water for 12 h, followed by complete grinding of the samples with a Potter homogeniser. The precipitation of protein should be done with 2.5:1 25% TCA:homogenate (v/v). The protocol for extraction and precipitation of protein developed in this study was tested with other macroalgae (Aglaothamnion uruguayense, Caulerpa fastigiata, Chnoospora minima, Codium decorticatum, Dictyota menstrualis, Padina gymnospora and Pterocladiella capillacea) and microalgae (Amphidinium carterae, Dunaliella tertiolecta, Hillea sp., Isochrysis galbana and Skeletonema costatum). Comparison with the actual protein content determined from the sum of amino acid residues, suggests that Lowry's method should be used instead of Bradford's using bovine serum albumin (BSA) as protein standard instead of casein. This may be related to the reactivity of the protein standards and the greater similarity in the amino acid composition of BSA and algae. The current results should contribute to more accurate protein determinations in marine algae.

Impact of HIV-1 subtype and antiretroviral therapy on protease and reverse transcriptase genotype: Results of a global collaboration

Abstract: Background The genetic differences among HIV-1 subtypes may be critical to clinical management and drug resistance surveillance as antiretroviral treatment is expanded to regions of the world where diverse non-subtype-B viruses predominate.

Swine and Poultry Pathogens: the Complete Genome Sequences of Two Strains of Mycoplasma hyopneumoniae and a Strain of Mycoplasma synoviae

Abstract: This work reports the results of analyses of three complete mycoplasma genomes, a pathogenic (7448) and a nonpathogenic (J) strain of the swine pathogen Mycoplasma hyopneumoniae and a strain of the avian pathogen Mycoplasma synoviae; the genome sizes of the three strains were 920,079 bp, 897,405 bp, and 799,476 bp, respectively. These genomes were compared with other sequenced mycoplasma genomes reported in the literature to examine several aspects of mycoplasma evolution. Strain-specific regions, including integrative and conjugal elements, and genome rearrangements and alterations in adhesin sequences were observed in the M. hyopneumoniae strains, and all of these were potentially related to pathogenicity. Genomic comparisons revealed that reduction in genome size implied loss of redundant metabolic pathways, with maintenance of alternative routes in different species. Horizontal gene transfer was consistently observed between M. synoviae and Mycoplasma gallisepticum. Our analyses indicated a likely transfer event of hemagglutinin-coding DNA sequences from M. gallisepticum to M. synoviae.

Theory and Ab Initio Calculation of Radiative Lifetime of Excitons in Semiconducting Carbon Nanotubes

Abstract: We present a theoretical analysis and first-principles calculation of the radiative lifetime of excitons in semiconducting carbon nanotubes. An intrinsic lifetime of the order of 10 ps is computed for the lowest optically active bright excitons. The intrinsic lifetime is, however, a rapid increasing function of the exciton momentum. Moreover, the electronic structure of the nanotubes dictates the existence of dark excitons near in energy to each bright exciton. Both effects strongly influence measured lifetime. Assuming a thermal occupation of bright and dark exciton bands, we find an effective lifetime of the order of 10 ns at room temperature, in good accord with recent experiments.

Construct validity of the Medical Outcomes Study's social support scale adapted to Portuguese in the Pró-Saúde Study

Abstract: This paper evaluates the construct validity of the Medical Outcomes Study's social support scale adapted to Portuguese, when utilized in a cohort study among non-faculty civil servants at a university in Rio de Janeiro, Brazil (Pro-Saude Study). Baseline data were obtained in 1999, when 4,030 participants (92.0% of those eligible) completed a multidimensional self-administered questionnaire at the workplace. From the original scale's five social support dimensions, factor analysis of the data extracted only three dimensions: positive social interaction/affective support; emotional/information support; and material support. We estimated associations between social support dimensions and socio-demographic, health, and well being-related characteristics. We confirmed the hypotheses that less isolated individuals, those with better self-rated health, those who reported more participation in group activities, and those with no evidence of common mental disorders reported better perception of social support. In conclusion, we found good evidence for a high construct validity of this scale, supporting its use in future analyses in the Pro-Saude Study and in similar population groups.

A freezing-like posture to pictures of mutilation.

Abstract: Postural sway and heart rate were recorded in young men viewing emotionally engaging pictures. It was hypothesized that they would show a human analog of "freezing" behavior (i.e., immobility and heart rate deceleration) when confronted with a sustained block of unpleasant (mutilation) images, relative to their response to pleasant/arousing (sport action) or neutral (objects) pictures. Volunteers stood on a stabilometric platform during picture viewing. Significantly reduced body sway was recorded during the unpleasant pictures, along with increased mean power frequency (indexing muscle stiffness). Heart rate during unpleasant pictures also showed the expected greater deceleration. This pattern resembles the "freezing" and "fear bradycardia" seen in many species when confronted with threatening stimuli, mediated by neural circuits that promote defensive survival.

A new heuristic reconfiguration algorithm for large distribution systems

Abstract: This paper presents a reconfiguration algorithm that is specially suited to large-scale distribution systems. The algorithm uses a heuristic strategy that starts with the system in a meshed status, with all maneuverable switches closed. The choice of the switches to be opened is based on the calculation of the minimum total system losses, using a load-flow program. A refinement on this procedure, based on branch status exchange, is described. The paper includes results and comparisons on test systems utilized in three classical papers published in the technical literature. Results obtained on a real large-scale distribution system are also presented.

Interaction of cellular prion and stress-inducible protein 1 promotes neuritogenesis and neuroprotection by distinct signaling pathways.

Abstract: Understanding the physiological function of the cellular prion (PrPc) depends on the investigation of PrPc-interacting proteins. Stress-inducible protein 1 (STI1) is a specific PrPc ligand that promotes neuroprotection of retinal neurons through cAMP-dependent protein kinase A (PKA). Here, we examined the signaling pathways and functional consequences of the PrPc interaction with STI1 in hippocampal neurons. Both PrPc and STI1 are abundantly expressed and highly colocalized in the hippocampus in situ, indicating that they can interact in vivo. Recombinant STI1 (His6-STI1) added to hippocampal cultures interacts with PrPc at the neuronal surface and elicits neuritogenesis in wild-type neurons but not in PrPc-null cells. This effect was abolished by antibodies against either PrPc or STI1 and was dependent on the STI1 domain that binds PrPc. Binding of these proteins induced the phosphorylation/activation of the mitogen-activated protein kinase, which was essential for STI1-promoted neuritogenesis. His6-STI1, but not its counterpart lacking the PrPc binding site, prevented cell death via PKA activation. These results demonstrate that two parallel effects of the PrPc–STI1 interaction, neuritogenesis and neuroprotection, are mediated by distinct signaling pathways.