Transmission dynamics of the etiological agent of SARS in Hong Kong: impact of public health interventions

We present an analysis of the first 10 weeks of the severe acute respiratory syndrome (SARS) epidemic in Hong Kong. The epidemic to date has been characterized by two large clusters-initiated by two separate "super-spread" events (SSEs)-and by ongoing community transmission. By fitting a stochastic model to data on 1512 cases, including these clusters, we show that the etiological agent of SARS is moderately transmissible. Excluding SSEs, we estimate that 2.7 secondary infections were generated per case on average at the start of the epidemic, with a substantial contribution from hospital transmission. Transmission rates fell during the epidemic, primarily as a result of reductions in population contact rates and improved hospital infection control, but also because of more rapid hospital attendance by symptomatic individuals. As a result, the epidemic is now in decline, although continued vigilance is necessary for this to be maintained. Restrictions on longer range population movement are shown to be a potentially useful additional control measure in some contexts. We estimate that most currently infected persons are now hospitalized, which highlights the importance of control of nosocomial transmission.     

Chemical Composition and Antioxidant Activity of the Main Fruits,Tubers and Legumes Traditionally Consumed in the Andean Regions of Ecuador as a Source of Health-Promoting Compounds

Plant Foods for Human Nutrition - Thirteen fruits, eight legumes and three tubers consumed in the Andean regions of Ecuador were studied to determine their bioactive compounds, organic acids,...     

Seasonal dynamics of Microcystis spp. and their toxigenicity as assessed by qPCR in a temperate reservoir

Blooms of toxic cyanobacteria are becoming increasingly frequent, mainly due to water quality degradation. This work applied qPCR as a tool for early warning of microcystin(MC)-producer cyanobacteria and risk assessment of water supplies. Specific marker genes for cyanobacteria, Microcystis and MC-producing Microcystis, were quantified to determine the genotypic composition of the natural Microcystis population. Correlations between limnological parameters, pH, water temperature, dissolved oxygen and conductivity and MC concentrations as well as Microcystis abundance were assessed. A negative significant correlation was observed between toxic (with mcy genes) to non-toxic (without mcy genes) genotypes ratio and the overall Microcystis density. The highest proportions of toxic Microcystis genotypes were found 4-6 weeks before and 8-10 weeks after the peak of the bloom, with the lowest being observed at its peak. These results suggest positive selection of non-toxic genotypes under favorable environmental growth conditions. Significant positive correlations could be found between quantity of toxic genotypes and MC concentration, suggesting that the method applied can be useful to predict potential MC toxicity risk. No significant correlation was found between the limnological parameters measured and MC concentrations or toxic genotypes proportions indicating that other abiotic and biotic factors should be governing MC production and toxic genotypes dynamics. The qPCR method here applied is useful to rapidly estimate the potential toxicity of environmental samples and so, it may contribute to the more efficient management of water use in eutrophic systems.     

Antioxidant and antiproliferative activities of heterofucans from the seaweed Sargassum filipendula

Fucan is a term used to denominate a type of polysaccharide which contains substantial percentages of l-fucose and sulfate ester groups. We obtained five heterofucans from Sargassum filipendula by proteolytic digestion followed by sequential acetone precipitation. These heterofucans are composed mainly of fucose, glucose, glucuronic acid, galactose and sulfate. These fucans did not show anticoagulant activity in PT and aPTT tests. Their antioxidant activity was evaluated using the follow tests; total antioxidant capacity, scavenging hydroxyl and superoxide radicals, reducing power and ferrous ion [Fe(II)] chelating. All heterofucans displayed considerable activity, especially SF-1.0v which showed the most significant antioxidant potential with 90.7 ascorbic acid equivalents in a total antioxidant capacity test and similar activity when compared with vitamin C in a reducing power assay. The fucan antiproliferative activity was performed with HeLa, PC3 and HepG2 cells using MTT test. In all tested conditions the heterofucans exhibited a dose-dependent effect. The strongest inhibition was observed in HeLa cells, where SF-1.0 and SF-1.5 exhibited considerable activity with an IC50 value of 15.69 and 13.83 μM, respectively. These results clearly indicate the beneficial effect of S. filipendula polysaccharides as antiproliferative and antioxidant. Further purification steps and additional studies on structural features as well as in vivo experiments are needed to test the viability of their use as therapeutic agents.     

Unravelling the Dermatological Potential of the Brown Seaweed Carpomitra costata

The ever-increasing interest in keeping a young appearance and healthy skin has leveraged the skincare industry. This, coupled together with the increased concern regarding the safety of synthetic products, has boosted the demand for new and safer natural ingredients. Accordingly, the aim of this study was to evaluate the dermatological potential of the brown seaweed Carpomitra costata. The antioxidant, anti-enzymatic, antimicrobial, photoprotective and anti-inflammatory properties of five C. costata fractions (F1–F5) were evaluated. The ethyl acetate fraction (F3) demonstrated the most promising results, with the best ability to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals (EC₅₀ of 140.1 µg/mL) and the capacity to reduce reactive oxygen species (ROS) production promoted by UVA and UVB radiation in 3T3 cells, revealing its antioxidant and photoprotective potential. This fraction also exhibited the highest anti-enzymatic capacity, inhibiting the activities of collagenase, elastase and tyrosinase (IC₅₀ of 7.2, 4.8 and 85.9 µg/mL, respectively). Moreover, F3 showed anti-inflammatory potential, reducing TNF-α and IL-6 release induced by LPS treatment in RAW 264.7 cells. These bioactivities may be related to the presence of phenolic compounds, such as phlorotannins, as demonstrated by NMR analysis. The results highlight the potential of C. costata as a source of bioactive ingredients for further dermatological applications.     

Assessment of rice hydraulic loading impacts on groundwater and salinity levels

This paper describes the impact of rice hydraulic loading (percentage area under rice crop) on groundwater levels and salinity in the Murrumbidgee irrigation area (MIA), Australia using a MODFLOW-based modelling approach. The model simulations show that the groundwater levels will be in equilibrium after a fall of approximately 1 m under most of the areas, however, the groundwater salinity levels will rise by more than 1,000 μs/cm in most parts of irrigation area. If the rice growing area is reduced by 50 and 75%, there can be a net decline in groundwater levels during the first 2 years and then a new quasi-equilibrium will be established. To downscale these results at the farm level, SWAGMAN Farm model in conjunction with groundwater outflow rates obtained from a three-dimensional MODFLOW model was applied for determining net recharge rates under rice for different areas within the MIA. The highest net recharge during 2005–2006 season was 0.84 ML/ha (84 mm) in parts of the irrigation system, whereas the average net recharge due to rice hydraulic loading for the whole MIA during 2005–2006 season was estimated as 0.34 ML/ha (34 mm).     

Partitioning of glutenin flour of special wheat using aqueous two-phase systems

The partitioning behavior of the glutenin proteins was evaluated in aqueous two-phase systems (ATPSs) formed by sulfate salts (lithium or sodium) and poly(ethylene glycol) (PEG) with average molar mass of 1500 g mol⁻¹ or 4000 g mol⁻¹. The partition coefficients for the glutenin proteins in each ATPS were investigated as a function of the temperature (278.2 K–318.2 K), tie line length (TLL) and electrolyte nature. In all ATPS, the majority of glutenin proteins spontaneously concentrate in the polymer-rich phase (K_p > 1). The partition coefficient is very dependent on the salt nature and the ATPS formed by PEG + lithium sulfate presents higher K_p values as compared with the ATPS formed PEG + sodium sulfate. An increase of molar mass of polymer promotes a decrease of K_p. Thermodynamic parameters of transfer (Δ_trG, Δ_trH and Δ_trS) were obtained by the application of the Van’t Hoff equation (VHE). The values obtained by VHE indicate that the transfer of glutenin proteins to the polymer-rich phase has an enthalpic origin.     

N-Terminal Protease Gene Phylogeny Reveals the Potential for Novel Cyanobactin Diversity in Cyanobacteria

Cyanobactins are a recently recognized group of ribosomal cyclic peptides produced by cyanobacteria, which have been studied because of their interesting biological activities. Here, we have used a PCR-based approach to detect the N-terminal protease (A) gene from cyanobactin synthetase gene clusters, in a set of diverse cyanobacteria from our culture collection (Laboratory of Ecotoxicology, Genomics and Evolution (LEGE) CC). Homologues of this gene were found in Microcystis and Rivularia strains, and for the first time in Cuspidothrix, Phormidium and Sphaerospermopsis strains. Phylogenetic relationships inferred from available A-gene sequences, including those obtained in this work, revealed two new groups of phylotypes, harboring Phormidium, Sphaerospermopsis and Rivularia LEGE isolates. Thus, this study shows that, using underexplored cyanobacterial strains, it is still possible to expand the known genetic diversity of genes involved in cyanobactin biosynthesis.     

BDDE-Inspired Chalcone Derivatives to Fight Bacterial and Fungal Infections

The growing number of infectious diseases around the world threatens the effective response of antibiotics, contributing to the increase in antibiotic resistance seen as a global health problem. Currently, one of the main challenges in antimicrobial drug discovery is the search for new compounds that not only exhibit antimicrobial activity, but can also potentiate the antimicrobial activity and revert antibiotics’ resistance, through the interference with several mechanisms, including the inhibition of efflux pumps (EPs) and biofilm formation. Inspired by macroalgae brominated bromophenol BDDE with antimicrobial activity, a series of 18 chalcone derivatives, including seven chalcones (9–15), six dihydrochalcones (16–18, and 22–24) and five diarylpropanes (19–21, and 25 and 26), was prepared and evaluated for its antimicrobial activity and potential to fight antibiotic resistance. Among them, chalcones 13 and 14 showed promising antifungal activity against the dermatophyte clinical strain of Trichophyton rubrum, and all compounds reversed the resistance to vancomycin in Enterococcus faecalis B3/101, with 9, 14, and 24 able to cause a four-fold decrease in the MIC of vancomycin against this strain. Compounds 17–24 displayed inhibition of EPs and the formation of biofilm by S. aureus 272123, suggesting that these compounds are inhibiting the EPs responsible for the extrusion of molecules involved in biofilm-related mechanisms. Interestingly, compounds 17–24 did not show cytotoxicity in mouse embryonic fibroblast cell lines (NIH/3T3). Overall, the results obtained suggest the potential of dihydrochalcones 16–18 and 22–24, and diarylpropanes 19–21, 25 and 26, as hits for bacterial EPs inhibition, as they are effective in the inhibition of EPs, but present other features that are important in this matter, such as the lack of antibacterial activity and cytotoxicity.