Susceptibility characterization of residual Brazilian populations of Triatoma infestans Klug, 1834 (Hemiptera: Reduviidae) to deltamethrin pyrethroid

INTRODUCTION: Despite years of efforts towards the elimination of Triatoma infestans in Brazil, residual foci still persist in some areas of the States of Bahia and Rio Grande do Sul. The persistence of these T. infestans populations in the country has two different origins of equal concern: operational failures or insecticide resistance. Thus, the objective of this study was to characterize the susceptibility profile of the residual Brazilian populations of T. infestans to deltamethrin. METHODS: The susceptibility reference lineage was derived from Cipein/Argentina. The populations studied were manually collected using a dislodging agent in peridomiciles in the States of Bahia (Novo Horizonte) and of Rio Grande do Sul (Santa Rosa and Doutor Maurício Cardoso). Serial dilutions of deltamethrin were prepared and applied at the dorsal abdomen of first instar nymphs. The control group received only pure acetone. Mortality was evaluated after 72h. Qualitative tests assessed the mortality of a diagnostic dose of 1xLD99 (2.76ng a.i./nymph) determined for the susceptibility reference lineage. RESULTS: The susceptibility profile characterization of the T. infestans populations revealed an RR50 ranging from 1.73 to 3.26. The mortality percentage in response to a diagnostic dose was 100%. The results obtained in the quantitative and qualitative assays corresponded for all populations. CONCLUSIONS: The results of this study indicate that the persistence of residual foci of T. infestans in Bahia and Rio Grande do Sul is not related to insecticide resistance but may be associated with operational failures. In Rio Grande do Sul, we must consider the possibility of continuous reinfestation by Argentinian individuals, which justifies active and efficient epidemiological surveillance.

Variability of susceptibility to deltamethrin in peridomestic Triatoma sordida from Triângulo Mineiro, State of Minas Gerais, Brazil

AbstractINTRODUCTION:Despite chemical and physical vector control strategies, persistent infestations of Triatoma sordida have been reported in a large part of Minas Gerais, Brazil, and the cause for this is little investigated. We aimed to characterize the deltamethrin toxicological profile in peridomestic T. sordidapopulations from Triângulo Mineiro area of Minas Gerais.METHODS:Susceptibility to deltamethrin was assessed in seventeen peridomestic T. sordida populations. Serial dilutions of deltamethrin in acetone (0.2µL) were topically applied on the first instar nymphs (F1; five days old; fasting weight, 1.2 ± 0.2mg). Dose response results were analyzed using Probit software, and the lethal doses, slope and resistance ratios were determined. Qualitative tests were also performed.RESULTS:The deltamethrin susceptibility profile of T. sordida populations revealed resistance ratios ranging from 0.84 to 2.8. The percentage mortality in response to a diagnostic dose was 100.0% in all populations.CONCLUSIONS:From our results, the lack of resistance to insecticides but persistent T. sordida infestations in the Triângulo Mineiro area may be because of: 1) environmental degradation facilitating dispersion of T. sordida , allowing colonization in artificial ecotopes; 2) operational failures; and 3) complexity of the peridomicile in the study area.These variables are being investigated.

Biodistribution Study of the Anaesthetic Sodium Phenobarbital Labelled with Technetium-99m in Swiss Mice Infected with Schistosoma mansoni Sambon, 1907

Technetium-99m (99mTc) is a radionuclide that has negligible enviromnental impact, is easily available, inexpensive and can be used as a radioactive tracer in biological experiences. In order to know the mode of action of sodium phenobarbital in moving adult Schistosoma mansoni worms from mesenteric veins to the liver, we labelled sodium phenobarbital (PBBT) with 99mTc and a biodistribution study in infected and non-infected Swiss mice was performed. The PBBT was incubated with stannous chloride used as reducing agent and with 99mTc, as sodium pertechnetate. The radioactivity labelling (%) was determined by paper ascending chromatography perfomed with acetone (solvent). The 99mTc-PBBT was administered by intraperitoneal route to Swiss mice infected eight weeks before. The animals were perfused after diferent periods of time (0,1,2,3,4 hr) when blood, spleen, liver, portal vein, mesenteric veins, stomach, kidneys and adult worms were isolated. The radioactivity present in these samples was counted in a well counter and the percentage was determined. The radioactivity was mainly taken up by the blood, kidney, liver and spleen. No radioactivity was found on the adult worms. We concluded that the worm shift was due to an action on the host of the sodium phenobarbital

Molluscicidal activity of Physalis angulata L. extracts and fractions on Biomphalaria tenagophila (d'Orbigny, 1835) under laboratory conditions

The main objective of this research is to evaluate the molluscicide activity of Physalis angulata L. Biomphalaria tenagophila specimens under laboratory conditions. Extracts and fractions were supplied by the Laboratório de Química de Produtos Naturais, Farmanguinhos-Fiocruz. Experiments were performed according to the methodology described by the World Health Organization for molluscicide tests using the concentrations from 0.1 to 500 mg/l of the extracts, fractions and of a pool of physalins modified steroids present in this species. The results show that ethyl acetate and acetone extracts from the whole plant, the ethanolic extracts of the roots and the physalins pool from stems and leaves were active. Only the whole plant extracts were available in sufficient quantity for the determination of LD50 and LD90 values.

The effect of Bulgarian propolis against Trypanosoma cruzi and during its interaction with host cells

Propolis has shown activity against pathogenic microorganisms that cause diseases in humans and animals. The ethanol (Et-Blg) and acetone (Ket-Blg) extracts from a Bulgarian propolis, with known chemical compositions, presented similar activity against tissue culture-derived amastigotes. The treatment of Trypanosoma cruzi-infected skeletal muscle cells with Et-Blg led to a decrease of infection and of the intracellular proliferation of amastigotes, while damage to the host cell was observed only at concentration 12.5 times higher than those affecting the parasite. Ultrastructural analysis of the effect of both extracts in epimastigotes revealed that the main targets were the mitochondrion and reservosomes. Et-Blg also affected the mitochondrion-kinetoplast complex in trypomastigotes, offering a potential target for chemotherapeutic agents.

Bioactivity of Indonesian mahogany, Toona sureni (Blume) (Meliaceae), against the red flour beetle, Tribolium castaneum (Coleoptera, Tenebrionidae)

Bioactivity of Indonesian mahogany, Toona sureni (Blume) (Meliaceae), against the red flour beetle, Tribolium castaneum (Coleoptera, Tenebrionidae). The insecticidal activity of Toona sureni (Blume) Merr. was evaluated considering repellency, mortality and progeny production of F1 adults of Tribolium castaneum (Herbst, 1797) (Coleoptera, Tenebrionidae). Dried extract of seeds of T. sureni was dissolved in acetone to prepare solution of various concentrations (0.5, 1.0, 2.5 and 5.0%). To test for repellency, the insects were exposed to treated filter paper. Mortality of larvae, pupae and adults was evaluated by the treatment of spraying the insects with different concentrations of T. sureni extract. Residual effect of the extract was also evaluated considering the production of progeny of F1 adults. The highest repellency (93.30%) of T. castaneum occurred at the highest concentration (5.0% suspension of T. sureni); while the lowest (0.0%) repellency occurred at 0.5% suspension after 1 day of treatment. The highest mortality against adults (86.71%), larvae (88.32%) and pupae (85%) occurred at 5% suspension at 8 days after application. There was a negative correlation between the concentrations of T. sureni and the production of F1 adult's progeny of T. castaneum. The highest number of progeny (147) of T. castaneum occurred in the control at 7 days after treatment; and the lowest number of progeny (43) occurred at 5.0% concentration in 1 day after treatment. The results show that T. sureni is toxic to T. castaneum and has the potential to control all stages of this insect in stored wheat.

Identificação de componentes de óleos voláteis: Análise espectroscópica de misturas de sesquiterpenos

This paper describes a chromatographic method to fractionate volatile oils and to identify their sesquiterpenic constituents. The fractionation process includes flash chromatography over silica gel and chromatography over silica gel/AgNO3, utilising pentane, CH2Cl2 and/or acetone as eluents. GC chromatograms were obtained in order to get the relative percentage of each constituent in the volatile oils, to get the retention time value of them as well as to analyse and combine the fractions eluted from the columns. Such procedure afford mixtures of sesquiterpenes which are analysed by GC/MS, 13C and ¹H NMR.

Presença de compostos carbonílicos no ar em ambientes internos na cidade de São Paulo

The presence of low carbonyl compounds (C1-C4) and glutaraldehyde was observed in 14 work-locations in São Paulo city, Brazil, during January to July 1997 period. The quantification of other carbonyls was not possible due to a sampling artifact caused probably by undesirable reactions between the ambient ozone and the organic substract of C18 cartridge used to collect carbonyls. High indoor concentrations, compared to outdoor levels, were observed for all compounds. Formaldehyde was the most abundant species (29 ppb) followed by acetone and acetaldehyde (25 and 17 ppb) with a small contribution of propanal, crotonaldehyde and C4 isomers (0.7 to 1.5 ppb) when related to the total indoor carbonyls level. Glutaraldehyde was observed only in two different occupational locations in a hospital at high concentrations (121 ppb). In general, high individual carbonyl levels as well as total carbonyls levels found in several locations indicated an unpropitious air quality for the occupants of these non-industrial sites.

Método colorimétrico para determinação de dióxido de nitrogênio atmosférico com preconcentração em coluna de c-18

An alternative analytical method for nitrogen dioxide (NO2) in atmosphere was developed. The collection of NO2 is performed by a Sep-Pack C-18 cartridge impregnated with 11% (v/v) of triethanolamine plus 3,6 % (v/v) of ethylene glycol plus 25 % (v/v) of acetone combined solution. When the impregnating is used, NO2 is collected with good repeatibility (CV = 3,3 %). The NO2 absorbed in the sampler was stripped from the sorbent with a methanol 5% (v/v) aqueous solution and was determined by colorimetry as nitrite by using the Griess-Saltzman reagent. The detection limit of 1,4 ppb for 60 min sampling at 0,5 L min-1 flow rate was obtained. Preparation and conditioning procedures for TEA-C-18 cartridge, sampling flow rate, absorption capacity and interference of other species are discussed.

Determinação da massa molar por crioscopia: terc-butanol, um solvente extremamente adequado

We intend to divulge an easy experiment that permits the determination of molar masses of various compounds by cryoscopy. The major advantage of this is the use of the tert-butyl alcohol as a solvent, which requires simple apparatus and easy procedures. The melting point of this alcohol is around 25 ºC, which makes it easy to freeze and then melt the solutions. This solvent has a high cryoscopic constant and is miscible with both polar and non-polar compounds. The molar masses of acetone, water, chloroform, dichloro-methane, ethanol, hexane, carbon tetrachloride and toluene were determined. The results were good except for water. Even though there are reliable techniques of molar mass determination nowadays, this method is still frequently taught in undergraduate courses.

Gerenciamento de resíduos químicos e águas servidas no laboratório de isótopos estáveis do CENA/USP

A system for disposal and recovery of the main effluents and chemical waist from isotope separation plants and enriched compounds-15N and 34S production has been carried out at the Stable Isotope Laboratory (LIE) of the CENA/USP. Around four hundred thousand liters of effluents has been recovered yearly. Among the recovered chemical wastes, the more relevant are: ammonia; brome; ammonium and sodium sulfate; sodium hydroxide; sulfur dioxide; and hydrochloric acid. Chemical wastes containg recoverable heavy metals (Ag, Cr and Cu) and solvents (methanol, ethanol and acetone) are processed and recovered. Gaseous emissions, mainly H2S are used for recovery of heavy metals solutions. The minimization of the residues waters, as well the reduction of electric energy consume was established using a water deionization system. A cost/effect balance of the process is reported.

Determinação de tanino em pedúnculo de caju: método da vanilina versus método do butanol ácido

To improve tannin assay in cashew apple, several parameters were examined, including (1) extraction solvents, (2) effects of water and boiling time on butanol acid reaction and (3) correlation between vanillin and butanol acid assay of tannin in cashew apples. The 50-70% acetone extracted the greatest amount of tannin from cashew apples. Concentrations of water in butanol reagents were adjusted and boiling time of butanol reaction was reduced at 15 min. Tannin of unripe cashew apples was purified on Sephadex LH-20, aiming to obtain tannin standard for butanol assay. The vanillin assay presented high correlation with the butanol acid assay.

NMR investigation and theoretical calculations of the effect of solvent on the conformational analysis of 4',7-di-hydroxy-8-prenylflavan

The NMR conformational study of 4',7-di-hydroxy-8-prenylflavan 1 was carried out in acetone-d6, DMSO-d6 and CDCl3 which enabled the proposition of three conformations, namely 1a, 1b and 1c, differing in the position of the prenyl group. Geometry optimizations performed using AM1 method showed that 1a (deltaHf = -86.2 kcal/mol) is as stable as 1b (deltaHf = -85.1 kcal/mol) and 1c (deltaHf = -85.4 kcal/mol). When the solvent was included, the calculations showed that the solute-solvent interactions could be explained either in the light of the electronic intermolecular delocalization or the electrostatic character between solute and solvent. Theoretical calculations (HF/6-31G*, deltaFT/BLYP/6-31G*, and deltaFT/B3LYP/6-31G*) showed that the combination of these types of interactions present in each solute-solvent system, dependent on the chemical properties of the solvent, lead to different spatial arrangements of the prenyl group, which in turn determined the conformation of 1.

Caracterização química do "pitch" em indústria de celulose e papel de Eucalyptus

The chemical analysis of the acetone, chloroform, toluene and methanol extracts of a pitch sample was carried out by IR and GC-MS, leading to the identification of sixty nine compounds, including fatty acids, alcohols and hydrocarbons. Analysis of the acetone extractive of a eucalyptus wood used in Brazil for pulp production was also carried out, resulting in identification of fifty nine compounds, including mainly fatty acids, phenolic compounds, beta-sitosterol and other steroids. This analysis showed that pitch formation had a contribution from wood extractives and other sources of contamination. The results obtained and the methodology applied can be used by the pulp industry to develop new methods of pitch control.

Extração de esterase de fígado suíno (PLE)

A simple, fast and low-cost methodology was optimized, seeking preparation of a crude pig liver esterase (PLE) concentrate. Basically, the method consisted of the following steps: liver homogenization, acetone washing, enzyme extraction and purification/concentration. Starting from 1 kg of fresh liver more than 200 kU of PLE suspension were obtained after 8 hours, at an estimated cost of US$0.21/kU. The PLE concentrate thus obtained was stable, showing 96-100% of the initial activity after 7 months in refrigerator at 4°C.