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Recurrent outbreaks of oral infection and isolated cases characterize the new epidemiological scenario of Chagas disease (CD) in the Brazilian Amazon. Acute Chagas disease (ACD) is common in Pará and Amazonas, Northeastern and Northwestern Brazilian Amazonia. In the present study, we describe the first molecularly characterized autochthonous case of ACD in Rondônia, Southwestern Amazonia. The patient, a 39-year-old male resident in the small city of Cujubim, presented typical ACD symptoms: fever, asthenia, myalgia, progressive dyspnea, swelling of the legs, and tiredness at minimal efforts, all compatible with ACD and indicative of cardiac involvement. A thick blood drop test revealed trypomastigote forms of Trypanosoma cruzi genotyped as TcIV. An epidemiological investigation ruled out oral infection, and support for vectorial transmission included the finding of Panstrongylus geniculatus positive for T. cruzi (TcIII and TcIV) inside the tent used by the patient when harvesting forest timber, and a circular cutaneous lesion resembling a chagoma of inoculation. Treatment with benznidazole led to blood parasite clearance as confirmed by molecular tests. Altogether, our findings fitted well into the ecological scenario where deforestation and colonization of forested areas represent an important risk factor to the adaptation of P. geniculatus to human habitats, favoring vectorial transmission of CD in the Amazonian region. [ABSTRACT FROM AUTHOR]

Background: The arthropod-borne Mayaro virus (MAYV) causes ‘Mayaro fever’, a disease of medical significance, primarily affecting individuals in permanent contact with forested areas in tropical South America. Recently, MAYV has attracted attention due to its likely urbanization. Currently, there are no licensed drugs against most mosquito-transmitted viruses. Here, we investigated the in vitro anti-MAYV activity of the flavonoids quercetin and its derivatives from the Brazilian shrub Bauhinia longifolia (Bong.) Steud. Methods: Flavonoids were purified by chromatographic fractionation from leaf extracts of B. longifolia and chemically identified as quercetin and quercetin glycosides using spectroscopic techniques. Cytotoxicity of purified flavonoids and of EtOAc- and n-BuOH-containing flavonoid mixtures was measured by the dye-uptake assay while their antiviral activity was evaluated by a virus yield inhibition assay. Results: The following flavonoids were purified from B. longifolia leaves: non-glycosylated quercetin and its glycosides guaijaverin, quercitrin, isoquercitrin, and hyperin. EtOAc and n-BuOH fractions containing these flavonoids demonstrated the highest antiviral activity of all tested substances, while quercetin had the highest antiviral activity amongst purified flavonoids. Quercetin, EtOAc, or n-BuOH fractions inhibited MAYV production by more than 90% at 25 μg/mL, displaying a stronger antiviral effect than the licensed antiviral ribavirin. A mixture of the isomers isoquercitrin and hyperin had a modest antiviral effect (IC90 = 104.9), while guaijaverin and quercitrin did not show significant antiviral activity. Conclusions: B. longifolia is a good source of flavonoids with anti-Mayaro virus activity. This is the first report of the activity of quercetin and its derivatives against an alphavirus. [ABSTRACT FROM AUTHOR]

A method for the determination of nitrobenzene with a sepiolite modified carbon paste electrode is presented. Nitrobenzene is adsorbed on the electrode at open circuit (pH 3.5), and determined by differential pulse voltammetry and cyclic voltammetry at pH 5.5 in 0.5 mol/l KNO. The calibration is linear up to 0.4 μg × ml. The method was applied to the determination of nitrobenzene in wines, beers and cider. The error was ±2% and the standard deviation 5%. [ABSTRACT FROM AUTHOR]

Chemically modified carbon paste electrodes are prepared by incorporating appropriate quantities of a zeolite directly into the paste mixture. Trace levels of mercury(II) can be preconcentrated on these electrodes. Cyclic voltammetry is used to quantify the accumulated ions. The response is characterized with respect to preconcentration, pH, and other variables. The procedure exhibits good linearity for 0.11 μg/ml-2.2 μg/ml mercury(II) ions and the peak current varies linearly with preconcentration time between 1 and 6 min for the conditions used. [ABSTRACT FROM AUTHOR]