Human risk assessment of benzene after a gasoline station fuel leak

OBJECTIVE: To assess the health risk of exposure to benzene for a community affected by a fuel leak. METHODS: Data regarding the fuel leak accident with, which occurred in the Brasilia, Federal District, were obtained from the Fuel Distributor reports provided to the environmental authority. Information about the affected population (22 individuals) was obtained from focal groups of eight individuals. Length of exposure and water benzene concentration were estimated through a groundwater flow model associated with a benzene propagation model. The risk assessment was conducted according to the Agency for Toxic Substances and Disease Registry methodology. RESULTS: A high risk perception related to the health consequences of the accident was evident in the affected community (22 individuals), probably due to the lack of assistance and a poor risk communication from government authorities and the polluting agent. The community had been exposed to unsafe levels of benzene (> 5 µg/L) since December 2001, five months before they reported the leak. The mean benzene level in drinking water (72.2 µg/L) was higher than that obtained by the Fuel Distributer using the Risk Based Corrective Action methodology (17.2 µg/L).The estimated benzene intake from the consumption of water and food reached a maximum of 0.0091 µg/kg bw/day (5 x 10-7 cancer risk per 106 individuals). The level of benzene in water vapor while showering reached 7.5 µg/m3 for children (1 per 104 cancer risk). Total cancer risk ranged from 110 to 200 per 106 individuals. CONCLUSIONS: The population affected by the fuel leak was exposed to benzene levels that might have represented a health risk. Local government authorities need to develop better strategies to respond rapidly to these types of accidents to protect the health of the affected population and the environment.

The influence of humidity on the residual action of benzene hexachloride (BHC)

In controlled humidity chambers in the laboratory differences in the absorption velocity of BHC were observed depending on the substrate sprayed. While BHC is no longer used in Chagas' disease control this data could have relevance to spraying houses in a controlprogramme with other insecticides.

Characterization of Sm14 related components in different helminths by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blotting analysis

Sm14 was the first fatty acid-binding protein homologue identified in helminths. Thereafter, members of the same family were identified in several helminth species, with high aminoacid sequence homology between them. In addition, immune crossprotection was also reported against Fasciola hepatica infection, in animals previously immunized with the Schistosoma mansoni vaccine candidate, r-Sm14. In the present study, data on preliminary sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blotting analysis of nine different helminth extracts focusing the identification of Sm14 related proteins, is reported. Out of these, three extracts - Ascaris suum (males and females), Echinostoma paraensei, and Taenia saginata - presented components that comigrated with Sm14 in SDS-PAGE, and that were recognized by anti-rSm14 policlonal serum, in Western blotting tests.

Experimental determination of benzene uptake rate in Tenax TA diffusive samplers

This paper proposes a methodology to predict benzene uptake rate in ambient air, using passive samplers with Tenax TA. Variations in the uptake rate were found to occur as a function of the sampling time; and were greater at the beginning of sampling. An empirical model was obtained and values for uptake rate agree with literature. Concentration prediction errors can be minimized by using sampling times of 4 to 14 days, thus avoiding the influence of excessive uptake rates in the initial days and the influence of back diffusion at the end of the sampling period.

Sodium dodecyl sulfate coated γ-alumina support modified by a new Schiff base for solid phase extraction and flame-AAS determination of lead and copper ions

A simple and fast approach for solid phase extraction is herein described, and used to determine trace amounts of Pb2+ and Cu2+ metal ions. The solid phase support is sodium dodecyl sulfate (SDS)-coated γ-alumina modified with bis(2-hydroxy acetophenone)-1,6-hexanediimine (BHAH) ligand. The adsorbed ions were stripped from the solid phase by 6 mL of 4 M nitric acid as eluent. The eluting solution was analyzed by flame atomic absorption spectrometry (FAAS). The sorption recovery of metal ions was investigated with regard to the effects of pH, amount of ligand, γ-alumina and surfactant and the amount and type of eluent. Complexation of BHAH with Pb2+ or Cu2+ ions was examined via spectrophotometry using the HypSpec program. The detection limit for Cu2+ was 7.9 µg L-1 with a relative standard deviation of 1.67%, while that for Pb2+ was 6.4 µg L-1 with a relative standard deviation of 1.64%. A preconcentration factor of 100 was achieved for these ions. The method was successfully applied to determine analyte concentrations in samples of liver, parsley, cabbage, and water.

Electrochemical properties of Cu4[PhN3C6H4N3(H)Ph]4(µ-O)2, a tetranuclear Copper(II) complex with 1-phenyltriazenido-2-phenyltriazene-benzene as ligand

Bis-(µ2-oxo)-tetrakis{[1-feniltriazene-1,3-diil)-2-(phenyltriazenil)benzene copper(II) is a tetranuclear complex which shows four Cu(II) ions coordinated by four 1,2-bis(phenyltriazene)benzene bridged ligands, with one diazoaminic deprotonated chain, and two O2- ligands. The complex reduces at E1/2 = -0.95 V vs Fc+/Fc, a two electrons process. Cyclic voltammetric and spectroelectrochemical studies showed a reversible process. When immobilized on carbon paste electrode, the complex electrocatalyses the reduction of O2 dissolved on aqueous solution at -0.3 V vs SCE potential. The obtained current shows linearity with O2 concentration.

Comparative studies of Yersinia pestis outer membrane isolation techniques and their potential use in plague epidemiology

In the present study three techniques for obtaining outer membrane enriched fractions from Yersinia pestis were evaluated. The techniques analysed were: differential solubilization of the cytoplasmic membrane with Sarkosyl or Triton X-100, and centrifugation in sucrose density gradients. The sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of outer membrane isolated by the different methods resulted in similar protein patterns. The measurement of NADH-dehydrogenase and succinate dehydrogenase (inner membrane enzymes) indicated that the outer membrane preparations obtained by the three methods were pure enough for analytical studies. In addition, preliminary evidences on the potential use of outer membrane proteins for the identification of geographic variants of Y. pestis wild isolates are presented.

Neurotoxic activity and ultrastructural changes in muscles caused by the brown widow spider Latrodectus geometricus venom

Brown widow spider (Latrodectus geometricus) venom (BrWSV) produces few local lesions and intense systemic reactions such as cramps, harsh muscle pains, nausea, vomiting and hypertension. Approximately 16 protein bands under reducing conditions and ~ 14 bands under non-reducing conditions on a 12.5% sodium dodecyl sulfate-polyacrylamide gel electrophoresis were observed. Neurotoxic clinical manifestations were confirmed in vivo, while proteolytic activity was demonstrated on gelatine film. Severe ultrastructural damages in mice skeletal muscles were observed at 3, 6, 12 and 24 h postinjection with at total of 45 µg of venom protein. Infiltration of eosinophils and ruptures of the cellular membranes were observed in the muscles along with swelling of the nuclear cover and interruption of the collagen periodicity. Altered mitochondrias and autophage vacuoles, nuclear indentation and mitochondria without cristae, slight increment of intermyofibrillar and subsarcolemic spaces and myelinic figures formation were also observed. In the capillary, endothelial membrane unfolding into the lumen was noticed; along with myelinic figures compatible with a toxic myopathy. Swollen sarcotubular systems with lysis of membrane, intense mitochondria autophagia and areas without pinocytic vesicles were observed. Swollen mitochondria surrounded by necrotic areas, myofibrillar disorganization and big vacuolas of the sarcotubular system, degenerated mitochondrium with formation of myelinic figure was seen. Glycogenosomes with small particulate, muscle type glycogen was noticed. Autophagic vacuole (autophagolysosomes) and necrotic areas were also noticed. These damages may be due to interactive effects of the multifactorial action of venom components. However, Latrodectus geometricus venom molecules may also be utilized as neuro therapeutic tools, as they affect neuronal activities with high affinity and selectivity. To our knowledge, the present study is the first ultrastructural report in the literature of muscle injuries and neurological and proteolytic activities caused by BrWSV.

ANTIFUNGAL ACTIVITY OF SILVER NANOPARTICLES OBTAINED BY GREEN SYNTHESIS

Silver nanoparticles (AgNPs) are metal structures at the nanoscale. AgNPs have exhibited antimicrobial activities against fungi and bacteria; however synthesis of AgNPs can generate toxic waste during the reaction process. Accordingly, new routes using non-toxic compounds have been researched. The proposal of the present study was to synthesize AgNPs using ribose as a reducing agent and sodium dodecyl sulfate (SDS) as a stabilizer. The antifungal activity of these particles against C. albicans and C. tropicalis was also evaluated. Stable nanoparticles 12.5 ± 4.9 nm (mean ± SD) in size were obtained, which showed high activity against Candida spp. and could represent an alternative for fungal infection treatment.

Detection of immunogenic proteins from Anopheles sundaicussalivary glands in the human serum

AbstractINTRODUCTION:The saliva of mosquitoes has an important role in the transmission of several diseases, including malaria, and contains substances with vasomodulating and immunomodulating effects to counteract the host physiological mechanisms and enhance pathogen transmission. As immunomodulatory components, salivary gland proteins can induce the generation of specific IgG antibodies in the host, which can be used as specific biomarkers of exposure to Anopheles sundaicus . The objective of this study was to identify immunogenic proteins from the salivary glands of Anopheles sundaicus by reaction with sera from individuals living in malaria-endemic areas who are thus exposed to Anopheles mosquitoes.METHODS:IgG antibodies targeting salivary gland proteins in serum samples from individuals living in malaria-endemic areas were measured by enzyme-linked immunosorbent assay (ELISA). Sera from healthy individuals living in non-endemic areas were used as negative controls. Determination of the presence of salivary gland immunogenic proteins was carried out by western blotting.RESULTS:Sixteen bands appeared in sodium dodecyl sulfate polyacrylamide gel electrophoresis, with molecule weights ranging from 22 to 144kDa. Among the exposed individuals, IgG responses to salivary gland proteins were variable. Protein bands with molecular weights of 46, 41, 33, and 31kDa were the most immunogenic. These immunogenic proteins were consistently recognized by pooled serum and individual samples from people living in malaria-endemic areas but not by negative controls.CONCLUSIONS:These results support the potential use of immunogenic proteins from the salivary glands of Anopheles as candidate markers of bite exposure or in malaria vaccines.

Chemical constituents from the stem of Brosimum potabile (Moraceae)

Three coumarins, 5-methoxypsoralene, xanthyletin, and (-)-marmesin, have been isolated from the ethanolic extract of the stem of the Amazonian plant Brosimum potabile. The structures were determined on the basis of NMR analyses and by comparison with spectroscopic data in the literature. The analysis of the hexane fractions by GC-MS in EIMS mode suggested the presence of (1-methylpentyl)-benzene; α,α-dimethyl-4-(1-methylethyl)-benzenemethanol; 1-methyl-3,5-bis(1-methylethyl)-benzene; urs-12-ene; chola-5,22-dien-3β-ol; cholesta-4,6-dien-3β-ol; sitosteryl 9(Z)-octadecenoate; cholesta-5,22-dien-3β-ol; cholesta-4,6,22-trien-3-one; and cholesta-4,22-dien-3-one. NMR data of other hexane fractions indicated the presence of 3β-acetoxy-lup-12,20(29)-diene; 3β-acetoxy-olean-12-ene; 3β-acetoxy-urs-12-ene; and adian-5-ene. All these compounds are first described in B. potabile.

Observações sôbre alguns diplópodos de interêsse agrícola

This paper deals with some Millipedes (Diplopoda), which have been verified associated with or attacking on cultivated plants. The following forms are reported: 1) Orthomorpha (Orthomorpha) coarctata (Saussure, 1860) - Enormous numbers of individuals belonging to this species, whose synanthropic habits are frequentely emphasized, were collected around coffee-plants kept in a nursery. Young plants (with 10 cm) are mentioned as damaged by the species, which gnaws the stem, just above the roots. The dusting with benzene hexachloride (BHC) was successfully employed to prevent the invasions. Other occurrences of O. coarctata are reported, ecological and biological informations being also added. 2) Orthomorpha (Kalorthomorpha) gracilis (C. L. Koch, 1847) - Observed frequentely associated with the former species, being however less numerous. Both forms are very active, seemming to be widely distributed throughout the State of S. Paulo. 3) Cylindroiulus (Aneuloboiulus) britannicus (Verhoeff, 1891) - This species represents the first european Millipede verified in Brazil, by O. SCHUBART (1942a). The Author obtained a few specimens associated with O. gracilis, from the roots of lettuce plants. The lesions shown by the stem just above the roots seem to be due to both species. 4) Alloporus setiger Broelemann, 1902; Gymnostreptus olivaceus Schubart, 1944 and Pseudonannolene tricolor Broelemann, 1902 - Total damages determined by these species (mainly G. olivaceus) were observed in cultures of sugar-beet and melon. Actually, the Millipedes destroyed entirely the roots of the former plant and the fruits of the latter, representing a serious pest, here reported by the first time. Ecological and bionomical data are also included. 5) Pseudonannolene sp. (possibly P. paulista Broelemann, 1902) - Verified gnawing sweet-potatoes, about the crackings exhibited by the tubers. The crackings in sweet-potatoes appear to result in certain instances from a root-knot nematodes infection (Meloidogyne sp). P. paulista was recentely observed attacking potatoes, destroying from 6 to 30% of the tubers, according to the variety (BOOCK & LORDELLO, 1952).

Characterization of plasma menbrane polypeptides of trypanosoma from bats

Cell surface proteins of Trypanosoma dionisii, Trypanosoma vespertilionis and Trypanosoma sp. (M238) were radiodinated and their distribution both in the detergent-poor (DPP) and dertergent-enriched phase (DRP) was studied using a phase separation technique in Triton X-114 as well as polyacrylamide gel electrophoresis in sodium dodecyl sulphate (SDS-PAGE). Significant differences were observed in the proteins present in the DRP when the three species of trypanosoma were compared. Two major bands with 88 and 70 KDa were observed in T. sp. (M238) but were not detectable in T. dionisii and T. vespertilionis. Three polypeptides whith 96, 77 and 60 KDa were identified in the DRP of T. vespertilionis. Three major bands with 84, 72 and 60 KDa were observed in the DRP of T. dionisii. Two polypeptides with 34-36 KDa present in the DPP, were observed in the three Trypanosome species analyzed. Our observations show that T. sp. (M238) has characteristic surface polypeptides not found in T. vespertilionis.

Evaluation of antibody responses in american visceral leishmaniasis by ELISA and immunoblot

American visceral leishmaniasis (AVL) is an important disease among children of northeast Brazil. In order to characterize antibody responses during AVL, sera of hospitalized patients were analyzed by ELISA and Western blot using a Leishmania chagasi antigen preparation. The ELISA was positive (asorbance [greater than or equals to] 0.196) at a serum dilution of 1:1024 in all patients at presentation, and fell to ward control levels over the following year. Only one of 72 control subjects tested positive, and that donor had a sibling with AVL. Immunoblots of the patients' sera recognized multiple bands, the most frequent of which were at approximately 116 kDa, 70 kDa, and 26 kDa. Less frenquently observed were bands at approximately 93 kDa, 74 kDa, 62 kDa, 46 kDa and 32 kDa. The ELISA responses and patterns of banding were distinctive for AVL, and could be used to differentiate patients with AVL from those with Chagas' disease of cutaneous leishmaniasis. Sera from six AVL patients followed for up to six weeks after treatment identified no new bands. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of surface iodinated parasite proteins showed one major band and four minor bands, whereas SDS-PAGE of biotinylated prarasite proteins revealed a banding pattern similar to those of patient sera. AVL appears to produce characteristic immunoblot patterns which can be used along with a sensitive screening ELISA to diagnose AVL.

Strain specific variation of outer membrane proteins of wild Yersinia pestis strains subjected to different growth temperatures

Three Yersinia pestis strains isolated from humans and one laboratory strain (EV76) were grown in rich media at 28§C and 37§C and their outer membrane protein composition compared by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-Page). Several proteins with molecular weights ranging from 34 kDa to 7 kDa were observed to change in relative abundance in samples grown at different temperatures. At least seven Y. pestis outer membrane proteins showed a temperature-dependent and strain-specific behaviour. Some differences between the outer membrane proteins of full-pathogenic wild isolates and the EV76 strain could aldso be detected and the relevance of this finding on the use of laboratory strains as a reference to the study of Y. pestis biological properties is discuted.