Structure and dynamics of phytoplankton in an Amazon lake, Brazil

Natural lake systems represent important reservoirs for residential water supply, fish production, recreational activities and enjoyment of their natural beauty. Nevertheless, human impacts may affect their health status resulting in degradation and loss of biodiversity. The aim of the present study was to obtain data on the health status of a natural lake located in an indigenous reservation in the Brazilian Amazon, using the phytoplankton community changes along the rainy (June) and dry (November) seasons of 2006. We collected water (temperature, pH, Secchi depth and conductivity) and phytoplankton samples from the subsurface, middle of the water column, and approximately 30 cm above the bottom, over 24-hour sampling periods, from a central station in the lake. Samples taken from biotic and abiotic variables were correlated using canonical correspondence analysis (CCA). Results showed that the lake exhibited high temperatures in both seasons, and showed thermal stratification only during the rainy season. Dissolved oxygen exhibited a clinograde pattern in the rainy season and high oxygen in the hypolimnion in the dry season. In the rainy season, the water near the bottom was acidic, turbid and had a greater concentration of phosphorus. Dissolved oxygen, conductivity, pH, nitrite, total phosphorus and total dissolved phosphorus exhibited diel variations in the rainy season, whereas water temperature, dissolved oxygen, total nitrogen and total dissolved phosphorus exhibited significant differences between hours of the day in the dry season. The phytoplankton was represented by 39 taxa, and Chlorophyta showed the greatest species richness, totaling 25 taxa. Among Chlorophyta, desmids were the most diverse, accounting 52%. Bacillariophyta (nine species) was the second most diverse group. Cyanophyta was represented by three species, including Merismopedia tenuissima, the most abundant taxon. Despite the occurrence of taxa that indicate organic pollution, their biomass and frequency indicate that the system is not currently threatened. Lake Caracaran? is an oligotrophic system, with low algal density and isolated blooming episodes due to its shallow depth.     

Accelerated hand bone mineral density loss is associated with progressive joint damage in hands and feet in recent-onset rheumatoid arthritis

Introduction

To investigate whether accelerated hand bone mineral density (BMD) loss is associated with progressive joint damage in hands and feet in the first year of rheumatoid arthritis (RA) and whether it is an independent predictor of subsequent progressive total joint damage after 4 years.

Methods

In 256 recent-onset RA patients, baseline and 1-year hand BMD was measured in metacarpals 2-4 by digital X-ray radiogrammetry. Joint damage in hands and feet were scored in random order according to the Sharp-van der Heijde method at baseline and yearly up to 4 years.

Results

68% of the patients had accelerated hand BMD loss (>-0.003 g/cm²) in the first year of RA. Hand BMD loss was associated with progressive joint damage after 1 year both in hands and feet with odds ratios (OR) (95% confidence intervals [CI]) of 5.3 (1.3-20.9) and 3.1 (1.0-9.7). In univariate analysis, hand BMD loss in the first year was a predictor of subsequent progressive total joint damage after 4 years with an OR (95% CI) of 3.1 (1.3-7.6). Multivariate analysis showed that only progressive joint damage in the first year and anti-citrullinated protein antibody positivity were independent predictors of long-term progressive joint damage.

Conclusions

In the first year of RA, accelerated hand BMD loss is associated with progressive joint damage in both hands and feet. Hand BMD loss in the first year of recent-onset RA predicts subsequent progressive total joint damage, however not independent of progressive joint damage in the first year.     

Thermodynamic and kinetic properties of the outer membrane cytochrome OmcF,a key protein for extracellular electron transfer in Geobacter sulfurreducens

Gene knock-out studies on Geobacter sulfurreducens have shown that the monoheme c-type cytochrome OmcF is essential for the extracellular electron transfer pathways involved in the reduction of iron and uranium oxy-hydroxides, as well as, on electricity production in microbial fuel cells. A detailed electrochemical characterization of OmcF was performed for the first time, allowing attaining kinetics and thermodynamic data. The heterogeneous electron transfer rate constant was determined at pH?7 (0.16?±?0.01?cm?s^?1) indicating that the protein displays high electron transfer efficiency compared to other monoheme cytochromes. The pH dependence of the redox potential indicates that the protein has an important redox-Bohr effect in the physiological pH range for G. sulfurreducens growth. The analysis of the structures of OmcF allowed us to assign the redox-Bohr centre to the side chain of His⁴⁷ residue and its pK_a values in the reduced and oxidized states were determined (pK_ox?=?6.73; pK_red?=?7.55). The enthalpy, entropy and Gibbs free energy associated with the redox transaction were calculated, pointing the reduced form of the cytochrome as the most favourable. The data obtained indicate that G. sulfurreducens cells evolved to warrant a down-hill electron transfer from the periplasm to the outer-membrane associated cytochrome OmcF.     

An overview of malaria transmission from the perspective of Amazon Anopheles vectors

In the Americas, areas with a high risk of malaria transmission are mainly located in the Amazon Forest, which extends across nine countries. One keystone step to understanding the Plasmodium life cycle in Anopheles species from the Amazon Region is to obtain experimentally infected mosquito vectors. Several attempts to colonise Ano- pheles species have been conducted, but with only short-lived success or no success at all. In this review, we review the literature on malaria transmission from the perspective of its Amazon vectors. Currently, it is possible to develop experimental Plasmodium vivax infection of the colonised and field-captured vectors in laboratories located close to Amazonian endemic areas. We are also reviewing studies related to the immune response to P. vivax infection of Anopheles aquasalis, a coastal mosquito species. Finally, we discuss the importance of the modulation of Plasmodium infection by the vector microbiota and also consider the anopheline genomes. The establishment of experimental mosquito infections with Plasmodium falciparum, Plasmodium yoelii and Plasmodium berghei parasites that could provide interesting models for studying malaria in the Amazonian scenario is important. Understanding the molecular mechanisms involved in the development of the parasites in New World vectors is crucial in order to better determine the interaction process and vectorial competence.     

Biocontrol evaluation of extracts and a major component,clusianone, from Clusia fluminensis Planch. & Triana against Aedes aegypti

Studies evaluated the effects of hexanic extracts from the fruits and flowers ofClusia fluminensis and the main component of the flower extract, a purified benzophenone (clusianone), against Aedes aegypti. The treatment of larvae with the crude fruit or flower extracts from C. fluminensis did not affect the survival ofAe. aegypti (50 mg/L), however, the flower extracts significantly delayed development of Ae. aegypti. In contrast, the clusianone (50 mg/L) isolate from the flower extract, representing 54.85% of this sample composition, showed a highly significant inhibition of survival, killing 93.3% of the larvae and completely blocking development of Ae. aegypti. The results showed, for the first time, high activity of clusianone against Ae. aegypti that both killed and inhibited mosquito development. Therefore, clusianone has potential for development as a biopesticide for controlling insect vectors of tropical diseases. Future work will elucidate the mode of action of clusianone isolated from C. fluminensis.     

Assessing ecological risk through automated drainage extraction and watershed delineation

Decision makers are frequently involved in projects requiring ecological risk definition, which are inherent to biological conservation process. It is important to recognize these risks in order to invest wisely in the management and protection of biological resources. In this matter, Geographic Information System tools and remote sensing data have been used frequently as important components in planning and management of conservation units, Rabus et al. (2003), Valeriano et al. (2009) and Valeriano et al. (2010) stressed the advantages of using data that were gathered during the Shuttle Radar Topographic Mission (SRTM) for biological and geomorphologic purposes. For Brazil's national territory, the SRTM data were refined (Valeriano, 2008) and offered as free access on the TOPODATA Project website (http://www.dsr.inpe.br/topodata) where geomorphometric information (including elevation data) at a resolution of 30 m are provided. The aim of this paper is to demonstrate an example of how TOPODATA products have been applied in order to determine the ecological risk of the border of a Conservation Unit, located in the State of São Paulo—Brazil, in the Brazilian Atlantic Forest, using automated drainage network and watershed extraction. A comparison between SRTM, TOPODATA, and ASTER DEM was carried out, showing an advantage of TOPODATA drainage network product. The vectors generated using this data are more similar to the official drainage network vectors than the drainage network extracted using ASTER-DEM or SRTM. The network product generated using ASTER-DEM produced many commission errors and the one generated using SRTM produced a poor network, with generalized vectors, less detailed than the others. The results showed that using the TOPODATA Project‘s Digital Elevation Model (DEM) can provide important data for ecological analysis and significant additional information for decision making, regarding drainage networks and watershed features. The produced map for border ecological risk showed to fit perfectly to the field work analyses, produced in other works. Furthermore, the extracted watershed polygons might furnish important information unrevealing best conservation unit boundaries, which means more efficient management and best biological conservation results.     

Antibiotics and the resistant microbiome

Since the discovery and clinical application of antibiotics, pathogens and the human microbiota have faced a near continuous exposure to these selective agents. A well-established consequence of this exposure is the evolution of multidrug-resistant pathogens, which can become virtually untreatable. Less appreciated are the concomitant changes in the human microbiome in response to these assaults and their contribution to clinical resistance problems. Studies have shown that pervasive changes to the human microbiota result from antibiotic treatment and that resistant strains can persist for years. Additionally, culture-independent functional characterization of the resistance genes from the microbiome has demonstrated a close evolutionary relationship between resistance genes in the microbiome and in pathogens. Application of these techniques and novel cultivation methods are expected to significantly expand our understanding of the interplay between antibiotics and the microbiome.     

Bone formation rather than inflammation reflects Ankylosing Spondylitis activity on PET-CT: a pilot study

Introduction

Positron Emission Tomography - Computer Tomography (PET-CT) is an interesting imaging technique to visualize Ankylosing Spondylitis (AS) activity using specific PET tracers. Previous studies have shown that the PET tracers [¹⁸F]FDG and [¹¹C](R)PK11195 can target inflammation (synovitis) in rheumatoid arthritis (RA) and may therefore be useful in AS. Another interesting tracer for AS is [¹⁸F]Fluoride, which targets bone formation. In a pilot setting, the potential of PET-CT in imaging AS activity was tested using different tracers, with Magnetic Resonance Imaging (MRI) and conventional radiographs as reference.

Methods

In a stepwise approach different PET tracers were investigated. First, whole body [¹⁸F]FDG and [¹¹C](R)PK11195 PET-CT scans were obtained of ten AS patients fulfilling the modified New York criteria. According to the BASDAI five of these patients had low and five had high disease activity. Secondly, an extra PET-CT scan using [¹⁸F]Fluoride was made of two additional AS patients with high disease activity. MRI scans of the total spine and sacroiliac joints were performed, and conventional radiographs of the total spine and sacroiliac joints were available for all patients. Scans and radiographs were visually scored by two observers blinded for clinical data.

Results

No increased [¹⁸F]FDG and [¹¹C](R)PK11195 uptake was noticed on PET-CT scans of the first 10 patients. In contrast, MRI demonstrated a total of five bone edema lesions in three out of 10 patients. In the two additional AS patients scanned with [¹⁸F]Fluoride PET-CT, [¹⁸F]Fluoride depicted 17 regions with increased uptake in both vertebral column and sacroiliac joints. In contrast, [¹⁸F]FDG depicted only three lesions, with an uptake of five times lower compared to [¹⁸F]Fluoride, and again no [¹¹C](R)PK11195 positive lesions were found. In these two patients, MRI detected nine lesions and six out of nine matched with the anatomical position of [¹⁸F]Fluoride uptake. Conventional radiographs showed structural bony changes in 11 out of 17 [¹⁸F]Fluoride PET positive lesions.

Conclusions

Our PET-CT data suggest that AS activity is reflected by bone activity (formation) rather than inflammation. The results also show the potential value of PET-CT for imaging AS activity using the bone tracer [¹⁸F]Fluoride. In contrast to active RA, inflammation tracers [¹⁸F]FDG and [¹¹C](R)PK11195 appeared to be less useful for AS imaging.     

Diaphragm adaptations in patients with COPD

Inspiratory muscle weakness in patients with COPD is of major clinical relevance. For instance, maximum inspiratory pressure generation is an independent determinant of survival in severe COPD. Traditionally, inspiratory muscle weakness has been ascribed to hyperinflation-induced diaphragm shortening. However, more recently, invasive evaluation of diaphragm contractile function, structure, and biochemistry demonstrated that cellular and molecular alterations occur, of which several can be considered pathologic of nature. Whereas the fiber type shift towards oxidative type I fibers in COPD diaphragm is regarded beneficial, rendering the overloaded diaphragm more resistant to fatigue, the reduction of diaphragm fiber force generation in vitro likely contributes to diaphragm weakness. The reduced diaphragm force generation at single fiber level is associated with loss of myosin content in these fibers. Moreover, the diaphragm in COPD is exposed to oxidative stress and sarcomeric injury. This review postulates that the oxidative stress and sarcomeric injury activate proteolytic machinery, leading to contractile protein wasting and, consequently, loss of force generating capacity of diaphragm fibers in patients with COPD. Interestingly, several of these presumed pathologic alterations are already present early in the course of the disease (GOLD I/II), although these patients appear not limited in their daily life activities. Treatment of diaphragm dysfunction in COPD is complex since its etiology is unclear, but recent findings indicate the ubiquitin-proteasome pathway as a prime target to attenuate diaphragm wasting in COPD.