Extensive microsatellite diversity in the human malaria parasite Plasmodium vivax

The population structure of Plasmodium vivax remains elusive. The markers of choice for large-scale population genetic studies of eukaryotes, short tandem repeats known as microsatellites, have been recently reported to be less polymorphic in R vivax. Here we investigate the microsatellite diversity and geographic structure in P vivax, at both local and global levels, using 14 new markers consisting of tri- or tetranucleotide repeats. The local-level analysis, which involved 50 field isolates from Sri Lanka, revealed unexpectedly high diversity (average virtual heterozygosity [H-E], 0.807) and significant multilocus linkage disequilibrium in this region of low malaria endemicity. Multiple-clone infections occurred in 60% of isolates sampled in 2005. The global-level analysis of field isolates or monkey-adapted strains identified 150 unique haplotypes among 164 parasites from four continents. Individual P. vivax isolates could not be unambiguously assigned to geographic populations. For example, we found relatively low divergence among parasites from Central America, Africa, Southeast Asia and Oceania, but substantial differentiation between parasites from the same continent (South Asia and Southeast Asia) or even from the same country (Brazil). Parasite relapses, which may extend the duration of P. vivax carriage in humans, are suggested to facilitate the spread of strains across continents, breaking down any pre-existing geographic structure. (C) 2008 Elsevier B.V. All rights reserved.

Genetic variability and natural selection at the ligand domain of the Duffy binding protein in brazilian Plasmodium vivax populations

Background: Plasmodium vivax malaria is a major public health challenge in Latin America, Asia and Oceania, with 130-435 million clinical cases per year worldwide. Invasion of host blood cells by P. vivax mainly depends on a type I membrane protein called Duffy binding protein (PvDBP). The erythrocyte-binding motif of PvDBP is a 170 amino-acid stretch located in its cysteine-rich region II (PvDBP(II)), which is the most variable segment of the protein. Methods: To test whether diversifying natural selection has shaped the nucleotide diversity of PvDBP(II) in Brazilian populations, this region was sequenced in 122 isolates from six different geographic areas. A Bayesian method was applied to test for the action of natural selection under a population genetic model that incorporates recombination. The analysis was integrated with a structural model of PvDBP(II), and T-and B-cell epitopes were localized on the 3-D structure. Results: The results suggest that: (i) recombination plays an important role in determining the haplotype structure of PvDBP(II), and (ii) PvDBP(II) appears to contain neutrally evolving codons as well as codons evolving under natural selection. Diversifying selection preferentially acts on sites identified as epitopes, particularly on amino acid residues 417, 419, and 424, which show strong linkage disequilibrium. Conclusions: This study shows that some polymorphisms of PvDBP(II) are present near the erythrocyte-binding domain and might serve to elude antibodies that inhibit cell invasion. Therefore, these polymorphisms should be taken into account when designing vaccines aimed at eliciting antibodies to inhibit erythrocyte invasion.

Phylogeography and evolutionary history of dengue virus type 3

In this study, we revisited the phylogeography of the three of major DENV-3 genotypes and estimated its rate of evolution, based on the analysis of the envelope (E) gene of 200 strains isolated from 31 different countries around the world over a time period of 50 years (1956-2006). Our phylogenetic analysis revealed a geographical subdivision of DENV-3 population in several country-specific clades. Migration patterns of the main DENV-3 genotypes showed that genotype I was mainly circumspect to the maritime portion of Southeast-Asia and South Pacific, genotype 11 stayed within continental areas in South-East Asia, while genotype III spread across Asia, East Africa and into the Americas. No evidence for rampant co-circulation of distinct genotypes in a single locality was found, suggesting that some factors, other than geographic proximity, may limit the continual dispersion and reintroduction of new DENV-3 variants. Estimates of the evolutionary rate revealed no significant differences among major DENV-3 genotypes. The mean evolutionary rate of DENV-3 in areas with long-term endemic transmissions (i.e., Indonesia and Thailand) was similar to that observed in the Americas, which have been experiencing a more recent dengue spread. We estimated the origin of DENV-3 virus around 1890, and the emergence of current diversity of main DENV-3 genotypes between the middle 1960s and the middle 1970s, coinciding with human population growth, urbanization, and massive human movement, and with the description of the first cases of DENV-3 hemorrhagic fever in Asia. (C) 2008 Elsevier B.V. All rights reserved.

Plasmodium falciparum Accompanied the Human Expansion out of Africa

Plasmodium falciparum is distributed throughout the tropics and is responsible for an estimated 230 million cases of malaria every year, with a further 1.4 billion people at risk of infection [1-3]. Little is known about the genetic makeup of P. falciparum populations, despite variation in genetic diversity being a key factor in morbidity, mortality, and the success of malaria control initiatives. Here we analyze a worldwide sample of 519 P. falciparum isolates sequenced for two housekeeping genes (63 single nucleotide polymorphisms from around 5000 nucleotides per isolate). We observe a strong negative correlation between within-population genetic diversity and geographic distance from sub-Saharan Africa (R(2) = 0.95) over Africa, Asia, and Oceania. In contrast, regional variation in transmission intensity seems to have had a negligible impact on the distribution of genetic diversity. The striking geographic patterns of isolation by distance observed in P. falciparum mirror the ones previously documented in humans [4-7] and point to a joint sub-Saharan African origin between the parasite and its host. Age estimates for the expansion of P. falciparum further support that anatomically modern humans were infected prior to their exit out of Africa and carried the parasite along during their colonization of the world.

Physical controls on carbon dioxide transfer velocity and flux in low-gradient river systems and implications for regional carbon budgets

Outgassing of carbon dioxide (CO(2)) from rivers and streams to the atmosphere is a major loss term in the coupled terrestrial-aquatic carbon cycle of major low-gradient river systems (the term ""river system"" encompasses the rivers and streams of all sizes that compose the drainage network in a river basin). However, the magnitude and controls on this important carbon flux are not well quantified. We measured carbon dioxide flux rates (F(CO2)), gas transfer velocity (k), and partial pressures (p(CO2)) in rivers and streams of the Amazon and Mekong river systems in South America and Southeast Asia, respectively. F(CO2) and k values were significantly higher in small rivers and streams (channels <100 m wide) than in large rivers (channels >100 m wide). Small rivers and streams also had substantially higher variability in k values than large rivers. Observed F(CO2) and k values suggest that previous estimates of basinwide CO(2) evasion from tropical rivers and wetlands have been conservative and are likely to be revised upward substantially in the future. Data from the present study combined with data compiled from the literature collectively suggest that the physical control of gas exchange velocities and fluxes in low-gradient river systems makes a transition from the dominance of wind control at the largest spatial scales (in estuaries and river mainstems) toward increasing importance of water current velocity and depth at progressively smaller channel dimensions upstream. These results highlight the importance of incorporating scale-appropriate k values into basinwide models of whole ecosystem carbon balance.

Development and characterization of microsatellite markers for turmeric (Curcuma longa)

P>Curcuma longa L. is a sterile, triploid, vegetatively-propagated crop cultivated mainly in Southeast Asia. When dried rhizomes are ground, the resulting yellow powder is used by the food industry as a natural food dye. Moreover, many pharmacological compounds have broadened the commercial application of the crop. However, conventional breeding is difficult and hence, improvement has been limited to germplasm selection. To better utilize the germplasm collections and facilitate genotype selection, a total of 17 polymorphic microsatellite loci were developed using a CT/GT/CTT enriched genomic library. All microsatellites resulted in amplified PCR products, showing a banding pattern of 2-11 polymorphic bands per locus, enabling genotype discrimination. These results can be used in further studies aimed at characterizing C. longa genetic resource collections and also to improve breeding strategies.

Global and diffuse solar irradiances in urban and rural areas in southeast Brazil

The seasonal evolution of daily and hourly values of global and diffuse solar radiation at the surface are compared for the cities of Sao Paulo and Botucatu, both located in Southeast Brazil and representative of urban and rural areas, respectively. The comparisons are based on measurements of global and diffuse solar irradiance carried out at the surface during a six year simultaneous period in these two cities. Despite the similar latitude and altitude, the seasonal evolution of daily values indicate that Sao Paulo receives, during clear sky days, 7.8% less global irradiance in August and 5.1% less in June than Botucatu. On the other hand, Sao Paulo receives, during clear sky days, 3.6% more diffuse irradiance in August and 15.6% more in June than Botucatu. The seasonal variation of the diurnal cycle confirms these differences and indicates that they are more pronounced during the afternoon. The regional differences are related to the distance from the Atlantic Ocean, systematic penetration of the sea breeze and daytime evolution of the particulate matter in Sao Paulo. An important mechanism controlling the spatial distribution of solar radiation, on a regional scale, is the sea breeze penetration in Sao Paulo, bringing moisture and maritime aerosol that in turn further increases the solar radiation scattering due to pollution and further reduces the intensity of the direct component of solar radiation at the surface. Surprisingly, under clear sky conditions the atmospheric attenuation of solar radiation in Botucatu during winter - the biomass burning period due to the sugar cane harvest - is equivalent to that at Sao Paulo City, indicating that the contamination during sugar cane harvest in Southeast Brazil has a large impact in the solar radiation field at the surface.

Magnetic fields and acute lymphoblastic leukemia in children: a systematic review of case-control studies

Leukemia incidence in children has increased worldwide in recent decades, particularly due to the rise in acute lymphoblastic leukemia. Studies have associated exposure to non-ionizing radiation generated by low frequency magnetic fields with childhood leukemia. The current article reviews the case-control studies published on this subject. Of 152 articles tracked in different databases, ten studies from North America, Asia, and Europe met the defined selection criteria, with patients diagnosed from 1960 to 2004. Methodological limitations were observed in these articles, including difficulties with the procedures for assessing exposure. An association may exist between exposure to low frequency magnetic fields and acute lymphoblastic leukemia in children, but this association is weak, preventing the observation of consistency in the findings. Future studies from a wider range of geographic regions should focus on the analysis of acute lymphoblastic leukemia, which is the subtype with the greatest impact on the increasing overall incidence of childhood leukemia.

Testing Evolutionary and Dispersion Scenarios for the Settlement of the New World

Background: Discussion surrounding the settlement of the New World has recently gained momentum with advances in molecular biology, archaeology and bioanthropology. Recent evidence from these diverse fields is found to support different colonization scenarios. The currently available genetic evidence suggests a ""single migration'' model, in which both early and later Native American groups derive from one expansion event into the continent. In contrast, the pronounced anatomical differences between early and late Native American populations have led others to propose more complex scenarios, involving separate colonization events of the New World and a distinct origin for these groups. Methodology/Principal Findings: Using large samples of Early American crania, we: 1) calculated the rate of morphological differentiation between Early and Late American samples under three different time divergence assumptions, and compared our findings to the predicted morphological differentiation under neutral conditions in each case; and 2) further tested three dispersal scenarios for the colonization of the New World by comparing the morphological distances among early and late Amerindians, East Asians, Australo-Melanesians and early modern humans from Asia to geographical distances associated with each dispersion model. Results indicate that the assumption of a last shared common ancestor outside the continent better explains the observed morphological differences between early and late American groups. This result is corroborated by our finding that a model comprising two Asian waves of migration coming through Bering into the Americas fits the cranial anatomical evidence best, especially when the effects of diversifying selection to climate are taken into account. Conclusions: We conclude that the morphological diversity documented through time in the New World is best accounted for by a model postulating two waves of human expansion into the continent originating in East Asia and entering through Beringia.

Relationship between median nerve somatosensory evoked potentials and spinal cord injury levels in patients with quadriplegia

Study design: Cross-sectional study. Objectives: To observe if there is a relationship between the level of injury by the American Spinal Cord Injury Association (ASIA) and cortical somatosensory evoked potential (SSEP) recordings of the median nerve in patients with quadriplegia. Setting: Rehabilitation Outpatient Clinic at the university hospital in Brazil. Methods: Fourteen individuals with quadriplegia and 8 healthy individuals were evaluated. Electrophysiological assessment of the median nerve was performed by evoked potential equipment. The injury level was obtained by ASIA. N(9), N(13) and N(20) were analyzed based on the presence or absence of responses. The parameters used for analyzing these responses were the latency and the amplitude. Data were analyzed using mixed-effect models. Results: N(9) responses were found in all patients with quadriplegia with a similar latency and amplitude observed in healthy individuals; N(13) responses were not found in any patients with quadriplegia. N(20) responses were not found in C5 patients with quadriplegia but it was present in C6 and C7 patients. Their latencies were similar to healthy individuals (P > 0.05) but the amplitudes were decreased (P < 0.05). Conclusion: This study suggests that the SSEP responses depend on the injury level, considering that the individuals with C6 and C7 injury levels, both complete and incomplete, presented SSEP recordings in the cortical area. It also showed a relationship between the level of spinal cord injury assessed by ASIA and the median nerve SSEP responses, through the latency and amplitude recordings. Spinal Cord (2009) 47, 372-378; doi:10.1038/sc.2008.147; published online 20 January 2009

In vitro cytotoxic activity of Baccharis dracunculifolia and propolis against HEp-2 cells

Baccharis dracunculifolia is the most important vegetal source of propolis in southeast Brazil, and researchers have been investigating its biological properties. Propolis is a complex resinous hive product collected by bees from several plants, showing a very complex chemical composition. It has been employed since ancient times due to its therapeutic properties, such as antimicrobial, anti-inflammatory, antioxidant, immunomodulatory and antitumour activities, among others. The goal of this work was to compare the cytotoxic action of B. dracunculifolia, propolis and two isolated compounds (caffeic and cinnamic acids) on human laryngeal epidermoid carcinoma (HEp-2) cells in vitro. These cells were incubated with different concentrations of each variable, and cell viability was assessed by the crystal violet method. Lower concentrations of B. dracunculifolia (extract and essential oil), propolis, as well as caffeic and cinnamic acids, showed no cytotoxic activity against HEp-2 cells. On the other hand, elevated concentrations (50 and 100 mu g per 100 mu L) exerted a cytotoxic action, and propolis showed a more efficient action than its vegetal source and isolated compounds. Further investigation is still needed in order to explore the potential of these variables as antitumour agents and to understand their mechanisms of action.

Clinical trials profile: Professionals and sites

Clinical trial is considered a breakthrough method in medicine and essential to the development of new drugs. Clinical trials that comply with international and national regulations require an appropriate infrastructure and team qualification. The goal of this study was to evaluate clinical trial groups in Brazil: professional qualification, site structure regulatory knowledge and Good Clinical Practice (GCP) adherence. This is a transversal study with investigators (PI) and sub investigator (SI). PI and SI data were initially identified from Curriculum Lattes from National Advice of Scientific and Technological Development. The study participants were submitted to a questionnaire, which was composed of qualitative and quantitative questions. A hundred PI and SI were interviewed. The most representative Brazilian regions were Southeast (68%) and South (18%). The main institutions involved were HCFMUSP complex and UNIFESP among others institutions. Academic graduation is observed in 86% of them and the higher degree is Doctorate (62%). 91% had GCP knowledge although only 74% had formal training. About the team, all of them are multidisciplinary with majority of nurses and pharmaceuticals. 88% had GCP knowledge although only 77% had formal training. 36%, 60% and 44% of clinical trials were in phase II,III and IV. In conclusion, researchers have appropriate skills and knowledge to perform clinical studies however there is still a need for training. The centers where the researchers work, have trained staff and adequate infrastructure for conducting clinical trials phase II,III and IV. (C) 2010 Elsevier Inc. All rights reserved.

Air Pollution and Mortality in Latin America The Role of Education

Background: People with less education in Europe, Asia, and the United States are at higher risk of mortality associated with daily and longer-term air pollution exposure. We examined whether educational level modified associations between mortality and ambient particulate pollution (PM(10)) in Latin America, using several timescales. Methods: The study population included people who died during 1998-2002 in Mexico City, Mexico; Santiago, Chile; and Sao Paulo, Brazil. We fit city-specific robust Poisson regressions to daily deaths for nonexternal-cause mortality, and then stratified by age, sex, and educational attainment among adults older than age 21 years (none, some primary, some secondary, and high school degree or more). Predictor variables included a natural spline for temporal trend, linear PM(10) and apparent temperature at matching lags, and day-of-week indicators. We evaluated PM(10) for lags 0 and I day, and fit an unconstrained distributed lag model for cumulative 6-day effects. Results: The effects of a 10-mu g/m(3) increment in lag 1 PM(10) on all nonextemal-cause adult mortality were for Mexico City 0.39% (95% confidence interval = 0.131/-0.65%); Sao Paulo 1.04% (0.71%-1.38%); and for Santiago 0.61% (0.40%-0.83%. We found cumulative 6-day effects for adult mortality in Santiago (0.86% [0.48%-1.23%]) and Sao Paulo (1.38% [0.85%-1.91%]), but no consistent gradients by educational status. Conclusions: PM(10) had important short- and intermediate-term effects on mortality in these Latin American cities, but associations did not differ consistently by educational level.

Centella asiatica water extract inhibits iPLA(2) and cPLA(2) activities in rat cerebellum

Centella asiatica (L.) Urb an is distributed widely in South America and Asia and is known as a therapeutic agent in folk medicine, capable of improving memory and treating several neurological disorders. Asiaticoside is one of the compounds found in C asiatica leaves that is suggested to be responsible for its pharmacological potential. Phospholipase A(2) (PLA(2)) is a group of enzymes that has abnormal activity in the central nervous system in some neuropsychiatric diseases. In this work, the asiaticoside present in C asiatica water extract was quantified by HPLC analysis. We also evaluated the activity of subtypes of PLA(2) in cerebellar samples from rats after C asiatica water extract treatment using a radioenzymatic assay. Asiaticoside was the major compound (84%) found in Centella water extract. We found a dose-dependent inhibitory effect of C asiatica water extract on the activity of Ca(2+)-independent PLA(2) (iPLA(2)) and cytosolic PLA(2) (cPLA(2)). The inhibition of these enzymes in the brain suggests that C asiatica may be useful to treat conditions associated with increased PLA(2) activity in the brain, such as epilepsy, stroke, multiple sclerosis and other neuropsychiatric disorders. (C) 2008 Elsevier GmbH. All rights reserved.

Revision of the Asian spider genus Pandava Lehtinen (Araneae: Titanoecidae): description of five new species and first record of Titanoecidae from Africa

The spider genus Pandava Lehtinen previously included two species, P. laminata (Thorell) and P. hunanensis Yin and Bao, known from Asia and the Pacific Islands. The genus is diagnosed by the reduced tegular process on the male palp and the anterior position of the copulatory openings on the female epigynum. In this paper, we present updated descriptions for the known species of Pandava and we describe five new species: Pandava shiva sp. nov. from Pakistan, Pandava sarasvati sp. nov. from Myanmar; Pandava ganesha sp. nov., Pandava kama sp. nov. and Pandava ganga sp. nov., all from India. We also update the generic distribution including the first records of Titanoecidae from Africa.