Multilevel assessment of carbamazepine effects: An integrative approach using zebrafish early-life stages

Carbamazepine (CBZ) is the most commonly used drug in epilepsy treatment, and its metabolites are commonly detected among persistent pharmaceuticals in the aquatic environment. This study aimed to investigate CBZ effects on early-life-stage zebrafish (Danio rerio) (from 2 to 168 hpf) by employing of an integrative approach linking endpoints from molecular to individual level: (i) development; (ii) locomotor activity; (iii) biochemical markers (lactate dehydrogenase, glutathione-S-transferase, acetylcholinesterase and catalase) and (iv) transcriptome analysis using microarray. A 168 h - LC50 of 73.4 mg L-1 and a 72 h - EC50 of 66.8 mg L-1 for hatching were calculated while developmental effects (oedemas and tail deformities) were observed at CBZ concentrations above 37.3 mg L-1. At the biochemical level, AChE activity proved to be the most sensitive parameter, as evidenced by its decrease across all concentrations tested (∼25% maximum reduction, LOEC (lowest observed effect concentration) < 0.6 μg L-1). Locomotor behaviour seemed to be depressed by CBZ although this effect was only evident at the highest concentration tested (50 mg L-1). Molecular analysis revealed a dose-dependent effect of CBZ on gene expression. Although only 25 genes were deregulated in organisms exposed to CBZ when compared to controls, both 0.6 and 2812 μg L-1 treatments impaired gene expression related to development (e.g. crygmxl1, org, klf2a, otos, stx16 and tob2) and the nervous system (e.g. Rtn3, Gdf10, Rtn3), while activated genes were associated with behavioural response (e.g. prlbr and taar). Altogether, our results indicate that environmentally relevant CBZ concentrations might affect biochemical and genetic traits of fish. Thus, the environmental risk of CBZ cannot be neglected, especially in a realistic scenario of constant input of domestic effluents into aquatic systems.

Occurrence, sources, and ecological risks of polycyclic aromatic hydrocarbons (PAHs) in the Amazon river

The Amazon is the largest river by discharge volume and one of the most biodiverse biomes in the world. Lately, there has been a rapid increase of the urban population in the region, which has been translated into a growing emission of organic contaminants such as polycyclic aromatic hydrocarbons (PAHs) into surface water bodies. This study provides the most comprehensive evaluation of the PAH contamination levels in surface waters of the Amazon basin. We investigated the occurrence and potential sources of 16 priority PAHs and characterised their risks for freshwater ecosystems. For this, we took 40 water samples from different sites along the Brazilian part of the Amazon River, including three major tributaries, and smaller rivers crossing the main urban areas. The results of this study show that PAHs are widespread contaminants in rivers of the Brazilian Amazon. The sum of the total concentration of the 16 priority PAHs reached values of 134 ng L^-1 in the Amazon River, and 163 ng L^-1 near densely populated areas. On the other hand, the total PAH concentration was generally lower in the monitored tributaries. In most samples, the contamination pattern was dominated by high molecular weight PAHs, suggesting a major contribution of pyrogenic sources, although petrogenic contamination was also present in some locations near urban areas. We assessed ecological risks posed by PAH mixtures using a hazard index. The results indicated that PAH contamination is not likely to pose direct toxic effects for Amazonian freshwater organisms, however continued monitoring is recommended near densely populated areas.

Large-scale monitoring and risk assessment of microplastics in the Amazon River

Microplastics (MPs) are one of the most widespread contaminants worldwide, yet their risks for freshwater ecosystems have seldom been investigated. In this study, we performed a large monitoring campaign to assess the presence and risks of MPs in Amazonian freshwater ecosystems. We investigated MP pollution in 40 samples collected along 1500 km in the Brazilian Amazon, including the Amazon River, three major tributaries, and several streams next to the most important urban areas. MPs in the 55-5000 µm size range were characterized (size, shape, color) by microscopy and identified (polymer composition) by infrared spectroscopy. Ecotoxicological risks were assessed using chronic Species Sensitivity Distributions for effects triggered by food dilution and tissue translocation using data alignment methods that correct for polydispersity of environmental MPs and bioaccessibility. This study shows that MPs are ubiquitous contaminants in Amazonian freshwater ecosystems, with measured concentrations (55-5000 µm) ranging between 5 and 152 MPs/m³ in the Amazon River and its main tributaries, and between 23 and 74,550 MPs/m³ in urban streams. The calculated Hazardous Concentration for the 5% of species (HC₅) derived from the SSDs for the entire MP range (1-5000 µm) were 1.6 × 10⁷ MPs/m³ (95% CI: 1.2 × 10⁶ - 4.0 × 10⁸) for food dilution, and 1.8 × 10⁷ MPs/m³ (95% CI: 1.5 × 10⁶ - 4.3 × 10⁸) for translocation. Rescaled exposure concentrations (1-5000 µm) in the Amazon River and tributaries ranged between 6.0 × 10³ and 1.8 × 10⁵ MPs/m³, and were significantly lower than the calculated HC₅ values. Rescaled concentrations in urban streams ranged between 1.7 × 10⁵ and 5.7 × 10⁸ MPs/m³, and exceeded both calculated HC₅ values in 20% of the locations. This study shows that ecological impacts by MP contamination are not likely to happen in the Amazon River and its major tributaries. However, risks for freshwater organisms may be expected in near densely populated areas, such as the cities of Manaus or Belem, which have limited wastewater treatment facilities.

Ecological risk assessment of pesticides in urban streams of the Brazilian Amazon

The use of pesticides in households and peri-urban areas of the Amazon has increased notably during the last years. Yet, the presence of these contaminants in Amazonian freshwater ecosystems remains unexplored. Here, we assessed the exposure to 18 pesticides and 5 transformation products in the Amazon River and in the urban streams of Manaus, Santarém, Macapá, and Belém (Brazil). Pesticide concentrations were analyzed by liquid and gas chromatography methods. Ecological risks were assessed following a two-tiered approach. First, hazard quotients and an overall hazard index were calculated using toxicity data for standard test species of primary producers, invertebrates, and fish. Second, the pesticides showing moderate-to-high ecological risks in the first tier were evaluated using Species Sensitivity Distributions (SSDs). Our study shows that pesticides are widespread in urban and peri-urban areas of the Brazilian Amazon. The frequency of detection was higher in urban streams than in the Amazon River, with some samples taken in Manaus, Santarém, and Belém containing up to 8 compounds. Most pesticides were measured at relatively low concentrations (ng L^-1), except for malathion, carbendazim and the bulk concentration of chlorpyrifos, which were monitored at concentrations above 100 ng L^-1. Based on the first-tier assessment, we found moderate-to-high risks for freshwater invertebrates for malathion, chlorpyrifos, and chlorpyrifos-methyl, and moderate risks for malathion to fish. The risk assessment performed with SSDs indicated high risks of malathion and chlorpyrifos-methyl in urban areas, with up to 15% and 5% of invertebrate species potentially affected, respectively. The bulk concentrations of chlorpyrifos resulted in high risks in some urban areas (14-22% of species affected) and in areas of the main river (32-44%) impacted by agriculture. We conclude that pesticide residues may contribute to a biodiversity impact in the Amazon and should be further monitored in urban and peri-urban areas, particularly after heavy rainfall events.

Pharmaceuticals and other urban contaminants threaten Amazonian freshwater ecosystems

Urban areas in the Brazilian Amazon have grown at an unprecedented rate during the last years. About 90% of the wastewater produced by these urban areas are discharged untreated into Amazonian freshwater ecosystems, constituting a potential environmental pathway for pharmaceuticals and other chemicals consumed by modern societies (e.g. psychostimulants, personal-care products, hormones). The distribution of these chemicals into the Amazon River and their potential risks for freshwater biodiversity have not been evaluated so far. Here, we show the results of the largest chemical monitoring campaign conducted in the Amazon region. We assessed exposure patterns for 43 pharmaceuticals and other urban contaminants in 40 sampling sites distributed along the Amazon River, three major tributaries (Negro, Tapajós and Tocantins Rivers), and four large cities of the Brazilian Amazon (Manaus, Santarém, Macapá, Belém). We assessed risks for freshwater biodiversity using species sensitivity distributions and mixture toxicity approaches. We found that urban areas constitute important hot-spots for chemical contamination, with mixtures containing up to 40 different compounds and exposure concentrations reaching the world's maxima for some of them. We show that chemical pollution can result in long-term effects for up to 50-80% of aquatic species next to urban areas. Moreover, we identified several ubiquitous compounds which can be used as tracers of anthropogenic pressure in the Amazon basin. We conclude that the chemical burden created by urbanization significantly contributes to a biodiversity loss in the region and should be further controlled.

Wide-scope screening of pharmaceuticals, illicit drugs and their metabolites in the Amazon River

Only a limited number of households in the Amazon are served by sewage collection or treatment facilities, suggesting that there might be a significant emission of pharmaceuticals and other wastewater contaminants into freshwater ecosystems. In this work, we performed a wide-scope screening to assess the occurrence of pharmaceuticals, illicit drugs and their metabolites in freshwater ecosystems of the Brazilian Amazon. Our study included 40 samples taken along the Amazon River, in three of its major tributaries, and in small tributaries crossing four important urban areas (Manaus, Santarém, Macapá, Belém). More than 900 compounds were investigated making use of target and suspect screening approaches, based on liquid chromatography coupled to high-resolution mass spectrometry with ion mobility separation. Empirical collision-cross section (CCS) values were used to help and confirm identifications in target screening, while in the suspect screening approach CCS values were predicted using Artificial Neural Networks to increase the confidence of the tentative identification. In this way, 51 compounds and metabolites were identified. The highest prevalence was found in streams crossing the urban areas of Manaus, Macapá and Belém, with some samples containing up to 30 - 40 compounds, while samples taken in Santarém showed a lower number (8 - 11), and the samples taken in the main course of the Amazon River and its tributaries contained between 1 and 7 compounds. Most compounds identified in areas with significant urban impact belonged to the analgesics and antihypertensive categories, followed by stimulants and antibiotics. Compounds such as caffeine, cocaine and its metabolite benzoylecgonine, and cotinine (the metabolite of nicotine), were also detected in areas with relatively low anthropogenic impact and showed the highest total prevalence. This study supports the need to improve the sanitation system of urban areas in the Brazilian Amazon and the development of follow-up studies aimed at quantifying exposure levels and risks for Amazonian freshwater biodiversity.

Auramine dyes induce toxic effects to aquatic organisms from different trophic levels: an application of predicted non-effect concentration (PNEC)

The dyes Auramine and Auramine O are used in several industrial products, despite the scarce information regarding their ecotoxicity. The aim of the present study was to assess the acute and chronic toxicity of both dyes to aquatic organisms from different trophic levels (Raphidocelis subcapitata, Daphnia similis, Hydra attenuata, and Danio rerio) and calculate their predicted non-effect concentrations (PNEC). Auramine and Auramine O induced toxicity to all selected test organisms with L(E)C50 values ranging from 300 to 4800 ug/L. Both dyes induced inhibition in the growth rate of exposed algae, negatively affecting the reproduction of D. similis and induced deformities in H. attenuata (clubbed tentacles and shortened tentacles) and D. rerio (edemas, tail malformation and delay in yolk sac absorption). PNEC values of 0.92 μg/L and 4.0 μg/L were obtained for Auramine and Auramine O, respectively, based on results of the most sensitive test system (algae). Test results were analyzed using the Criteria of Reporting and Evaluating Ecotoxicity Data (CRED), confirming their reliability and relevance. Thus, PNEC values can be used in future risk assessments of those substances in freshwater systems.

Toxicological findings about an anticancer fraction with casearins described by traditional and alternative techniques as support to the Brazilian Unified Health System (SUS)

ETHNOPHARMACOLOGICAL RELEVANCE

Extracts, essential oils and molecules from Casearia sylvestris have popularly shown pharmacological actions against chronic diseases, as anxiety, inflammation, cancer and dyslipidemia. In the context of antitumoral therapy, we investigated in vitro, ex vivo and in vivo toxicological changes induced by a Fraction with Casearins (FC) and its component Casearin X isolated from C. sylvestris on animal and vegetal cells, and upon invertebrates and mammals.

MATERIAL AND METHODS

Cytotoxicity was carried out using normal lines and absorbance and flow cytometry techniques, Artemia salina nauplii, Danio rerio embryos and meristematic cells from Allium cepa roots. Acute and 30 days-mice analysis were done by behavioral, hematological and histological investigations and DNA/chromosomal damages detected by alkaline Cometa and micronucleus assays.

RESULTS

FC was cytotoxic against lung and fibroblasts cells and caused DNA breaks, loss of integrity and mitochondrial depolarization on ex vivo human leukocytes. It revealed 24 h-LC₅₀ values of 48.8 and 36.7 μg/mL on A. salina nauplii and D. rerio embryos, reduced mitotic index of A. cepa roots, leading to cell cycle arrest at metaphase and anaphase and micronuclei. FC showed i.p. and oral LD₅₀ values of 80.9 and 267.1 mg/kg body weight. Subacute i.p. injections induced loss of weight, swelling of hepatocytes and tubules, tubular and glomerular hemorrhage, microvesicular steatosis, lung inflammatory infiltration, augment of GPT, decrease of albumin, alkaline phosphatase, glucose, erythrocytes, and lymphocytes, and neutrophilia (p > 0.05). FC-treated animals at 10 mg/kg/day i.p. caused micronuclei in bone marrow and DNA strand breaks in peripheral leukocytes.

CONCLUSIONS

This research postulated suggestive side effects after use of FC-related drugs, demonstrating FC as antiproliferative and genotoxic on mammal and meristematic cells, including human leukocytes, teratogenicity upon zebrafish embryos, myelosuppression, clastogenicity, and morphological and biochemical markers indicating liver as main target for FC-induced systemic toxicity.

CNTs coated charcoal as a hybrid composite material: Adsorption of fluoxetine probed by zebrafish embryos and its potential for environmental remediation

Although traditional water treatment systems can remove various substances from wastewater, these conventional systems fail to remove many chemical molecules that pose potential ecological and health risks. Carbon nanotubes (CNTs) appear attractive to adsorption of many substances, but CNTs adsorbed with toxic substances becomes a nanocomposite still more toxic. Here, we employ zebrafish embryos as biosensor to examine how a hybrid micro/nanostructured carbonaceous material (HMNC) derived from a combination of activated carbon (AC) with hydrophilic carbon nanotubes (CNTs) can remediate wastewater contaminated with the pharmaceutical fluoxetine hydrochloride (FLX). AC and HMNC are practically non-toxic to zebrafish embryos (LC₅₀ > 1000 mg.L^-1). HMNC addition to culture medium containing FLX significantly reduces sublethal effects and lethality. Interaction between FLX and HMNC involves chemical adsorption such that embryo co-exposure to HMNC adsorbed with FLX in the range of concentrations evaluated herein does not elicit any behavioral changes in zebrafish.

Impact of the glyphosate-based commercial herbicide, its components and its metabolite AMPA on non-target aquatic organisms

Glyphosate (GLY) is the active ingredient of several herbicide formulations widely used to control weeds in agricultural and non-agricultural areas. Due to the intensive use of GLY-based herbicides and their direct application on soils, some of their components, including the active ingredient, may reach the aquatic environment through direct run-off and leaching. The present study assessed the acute toxicity and genotoxicity of the GLY-based formulation Atanor 48 (ATN) and its major constituents GLY, surfactant polyethoxylated tallow amine (POEA), as well as the main metabolite of GLY aminomethylphosphonic acid (AMPA) on non-target aquatic organisms. The toxic effects of these chemicals were evaluated in the fish embryo acute toxicity test with zebrafish (Danio rerio), while genotoxic effects were investigated in the comet assays with cells from zebrafish larvae and rainbow trout gonad-2 (RTG-2). GLY and AMPA caused no acute toxic effect, while ATN and POEA induced significant lethal effects in zebrafish (LC50-96 h 76.50 mg/L and 5.49 mg/L, respectively). All compounds were genotoxic in comet experiments with zebrafish larvae (LOEC 1.7 mg/L for GLY, ATN, AMPA and 0.4 mg/L for POEA). Unlike in vivo, only POEA induced DNA damage in RTG-2 cells (LOEC 1.6 mg/L), suggesting that it is a direct acting genotoxic agent. In summary, these data indicate that the lethal effects on zebrafish early-life stages can be ranked in the following order from most to least toxic: surfactant POEA > formulation ATN > active ingredient GLY ≈ metabolite AMPA. Genotoxic effects were observed in both RTG-2 cells (only POEA) and zebrafish (all test compounds) with the lowest tested concentrations. Therefore, it is important to evaluate different toxicological endpoints as well as use different non-target organisms to predict the hazards of GLY-based formulations and their components and breakdown product to aquatic biota.

Exposure to ayahuasca induces developmental and behavioral alterations on early life stages of zebrafish

Ayahuasca is a psychoactive concoction prepared from the plants Banisteriopsis caapi and Psychotria viridis which are used ancestrally by Amazonian Indian populations and more recently, by Christian religious groups in Brazil and other countries. The aims of the present study were to identify the effects of ayahuasca on zebrafish embryo development and neurobehavior. Toxicity and developmental endpoints for zebrafish embryos were assessed from 0 to 1000 mg/L over 96 h of exposure. The effects on locomotor activity of zebrafish larvae were assessed using a video tracking system (ZebraBox) from 0 to 20 mg/L and after 120 and 144 h of exposure. The LC₅₀ of ayahuasca in zebrafish was determined as 236.3 mg/L. Ayahuasca exposure caused significant developmental anomalies in zebrafish embryos, mainly at the highest concentration tested, including hatching delay, loss of equilibrium, edema and the accumulation of red blood cells. Embryo behavior was also significantly affected, with decreased locomotor activity at the highest concentration tested. These results are in accordance with data obtained in mammal studies highlighting the possible risks of uncontrolled use of ayahuasca. Further research employing more specific behavior analysis could provide additional data on both therapeutic benefits and possible toxicological risk of ayahuasca.

Electrochemical remediation of amoxicillin: detoxification and reduction of antimicrobial activity

Amoxicillin (AMX) is one of the most commonly prescribed antibiotics around the world to treat and prevent several diseases in both human and veterinary medicine. Incomplete removal of AMX during wastewater treatment contributes to its presence in water bodies and drinking water. AMX is an emerging contaminant since its impact on the environment and human health remains uncertain. This contribution was aimed to evaluate the electrochemical oxidation (EO) of AMX using different anodes in tap water, NaCl or Na₂SO₄ solutions and to evaluate the potential toxicity of remaining AMX and its by-products on zebrafish early-life stages. Chemical intermediates generated after EO were determined by mass spectrometry and their resulting antimicrobial activity was evaluated. AMX did not induce significant mortality in zebrafish during extended exposure but affected zebrafish development (increased body length) from 6.25 mg/L to 25 mg/L and inhibited enzymatic biomarkers. Carbon modified with titanium oxide (TiO₂@C) anode achieved complete AMX removal in just a few minutes and efficiency of the supported electrolytes occurred in the following order: 0.1 M NaCl > 0.1 M Na₂SO₄ > 0.01 M NaCl > tap water. The order of potential toxicity to zebrafish early life-stages related to lethal and sublethal effects was as follows: 0.1 M Na₂SO₄ > 0.1 M NaCl >0.01 M NaCl = tap water. Additionally, the EO of AMX using TiO₂@C electrode with 0.01 M NaCl was able to inhibit the antimicrobial activity of AMX, reducing the possibility of developing bacterial resistance.

Phytotoxicity of silver nanoparticles to Lemna minor: Surface coating and exposure period-related effects

Silver nanoparticles (Ag NPs) exponential production raises concern about their environmental impact. The effects of Ag NPs to aquatic plants remain scarcely studied, especially in extended exposures. This paper aims to evaluate Ag NPs effects in Lemna minor at individual and sub-individual levels, focusing on three variables: Ag form (NPs versus ions - Ag⁺), NPs surface coating (citrate vs polyvinylpyrrolidone - PVP) and exposure period (7 vs 14days). Endpoints were assessed at individual level (specific growth rate, chlorosis incidence and number of fronds per colony) and sub-individual level (enzymatic activities of catalase (CAT), guaiacol peroxidase (GPx) and glutathione-S-transferase (GST)). Generally, plants exposed to all Ag forms underwent decays on growth rate and fronds per colony, and increases on chlorosis, GPX and GST, but no effects on CAT. The most sensitive endpoints were specific growth rate and GPx activity, showing significant effects down to 0.05mg/L for Ag NPs and 3μg/L for Ag⁺, after 14days. Ag⁺ showed higher toxicity with a 14d-EC₅₀ of 0.0037mg Ag/L. Concerning surface coating, PVP-Ag NPs were more deleterious on growth rate and fronds per colony, whereas citrate-Ag NPs affected more the chlorosis incidence and GPx and GST activities. The exposure period significantly affected chlorosis: 14days triggered a chlorosis increase in Ag⁺-exposed plants and a decrease in Ag NPs-exposed plants when compared to 7days. Ag NPs induced an oxidative stress status in cells, thus ensuing upregulated enzymatic activity as a self-defense mechanism. Since Ag NPs dissolution might occur on a steady and continuous mode along time, and the average longevity of fronds, we propose longer exposures periods than the recommended by the OECD guideline. This approach would provide more relevant and holistic evidences on the overall response of freshwater plants to Ag NPs in an ecological relevant scenario.

In vitro genotoxicity and in vivo subchronic evaluation of the anti-inflammatory pyrazole compound LQFM021

Scientific evidences have highlighted 5-(1-(3-fluorophenyl)-1H-pyrazol-4-yl)-2H-tetrazole (LQFM021) as a promising anti-inflammatory, analgesic and antinociceptive agent due to its effects on peripheral opioid receptors associated with activation of the nitric oxide/cGMP/K_ATP pathway. Despite these important pharmacological findings, toxicity data of LQFM021 are scarce. Thus, this study investigated the in vitro genotoxicity of LQFM021 through cytokinesis-block micronucleus assay (OECD Nº 487/2014). Moreover, zebrafish model was used to assess the embryotoxicity potential of LQFM021 using fish embryo toxicity test (OECD Nº 236/2013) with extended exposure to evaluate subchronic larval development. In vivo subchronic toxicity of LQFM021 in rats (OECD Nº 407/2008) was also conducted. This compound at the lower concentrations tested (3.1 and 31 μg/mL) did not promote changes in micronuclei frequency in HepG2 cells. However, in the higher concentrations of LQFM021 (310 and 620 μg/mL) triggered a significant increase of micronucleated HepG2 cells, showing an alert signal of potential genotoxicity. Regarding the oral treatment of rats with LQFM021 (62.5, 125 or 250 mg/kg) for 28 days, the main findings showed that LQFM021 promoted renal and liver changes in a dose-dependent manner, being irreversible damage for kidneys while liver tissue showed a recovery after 14 days post treatment. Regarding embryotoxicity, although the lower concentrations used did not show toxicity, the concentration of LQFM021 (39.8 and 100 mg/L) promoted malformations in zebrafish embryo-larvae stage, in especial cardiac tissue changes. In conclusion, anti-inflammatory compound LQFM021 seems to have some limiting factors as a new therapeutic option to be used orally and in high repeated doses, related to those found in the non-steroidal anti-inflammatory drugs (NSAIDs).

Ecotoxicological assessment of glyphosate-based herbicides: Effects on different organisms

Glyphosate-based herbicides are the most commonly used worldwide because they are effective and relatively nontoxic to nontarget species. Unlimited and uncontrolled use of such pesticides can have serious consequences for human health and ecological balance. The present study evaluated the acute toxicity and genotoxicity of 2 glyphosate-based formulations, Roundup Original (Roundup) and Glyphosate AKB 480 (AKB), on different organisms: cucumber (Cucumis sativus), lettuce (Lactuca sativa), and tomato (Lycopersicon esculentum) seeds, and microcrustacean Artemia salina and zebrafish (Danio rerio) early life stages. For the germination endpoint, only L. esculentum presented significant sensitivity to AKB and L. sativa to Roundup, whereas both formulations significantly inhibited the root growth of all species tested. Both AKB and Roundup induced significant toxicity to A. salina; both are classified as category 3, which indicates a hazard for the aquatic environment, according to criteria of the Globally Harmonized Classification System. However, Roundup was more toxic than AKB, with 48-h median lethal concentration (LC50) values of 14.19 mg/L and 37.53 mg/L, respectively. For the embryo-larval toxicity test, Roundup proved more toxic than AKB for the mortality endpoint (96-h LC50 values of 10.17 mg/L and 27.13 mg/L, respectively), whereas for the hatching parameter, AKB was more toxic than Roundup. No significant genotoxicity to zebrafish larvae was found. We concluded that AKB and Roundup glyphosate-based formulations are phytotoxic and induce toxic effects in nontarget organisms such as A. salina and zebrafish early life stages. Environ Toxicol Chem 2017;36:1755-1763. © 2016 SETAC.

Free radical-mediated pre-hemolytic injury in human red blood cells subjected to lead acetate as evaluated by chemiluminescence

The mechanisms by which Pb(2+) induces hemolysis are not completely understood. For this reason, the involvement of oxidative stress in the mechanism of Pb(2+)-induced pre-hemolytic lesion was investigated by exposing RBC to Pb(2+) in vitro and then separating the intact non-hemolysed RBC. Oxidative stress was investigated on human RBCs by tert-butyl hydroperoxide-initiated chemiluminescence method (CL). Our results revealed that lead-induced time and concentration-dependent hemolysis and CL time curves showed a very narrow correlation each other. GSH oxidation to GSSG and the stress index also increased significantly. Treatment of lead-exposed RBC with desferrioxamine, an iron-chelating agent or the chain-breaking antioxidant, Trolox, quenched light emission and inhibited hemolysis dramatically. Mannitol and sodium formate, (*)OH scavengers, on the contrary, did not inhibit CL or hemolysis, significantly. These data indicate that lead-induced lipid peroxide formation is mediated by a metal-driven Fenton reaction but do not support the direct involvement of hydroxyl radicals in this process. By contrast, our results revealed a decrease in light emission and decreased hemolysis in the presence of histidine, a singlet oxygen scavenger. Our results suggest that membrane damage and hemolysis of RBC are mediated by Pb(2+) through free radical reactions and that singlet oxygen plays a significant role in this process.

Cardiorespiratory responses of the facultative air-breathing fish jeju, Hoplerythrinus unitaeniatus (Teleostei, Erythrinidae), exposed to graded ambient hypoxia

The jeju, Hoplerythrinus unitaeniatus, is equipped with a modified part of the swim bladder that allows aerial respiration. On this background, we have evaluated its respiratory and cardiovascular responses to aquatic hypoxia. Its aquatic O2 uptake (V(O2)) was maintained constant down to a critical P(O2) (P(cO2)) of 40 mm Hg, below which V(O2) declined linearly with further reductions of P(iO2). Just below P(cO2), the ventilatory tidal volume (V(T)) increased significantly along with gill ventilation (V(G)), while respiratory frequency changed little. Consequently, water convection requirement (V(G)/V(O2)) increased steeply. The same threshold applied to cardiovascular responses that included reflex bradycardia and elevated arterial blood pressure (P(a)). Aerial respiration was initiated at water P(O2) of 44 mm Hg and breathing episodes and time at the surface increased linearly with more severe hypoxia. At the lowest water P(O2) (20 mm Hg), the time spent at the surface accounted for 50% of total time. This response has a character of a temporary emergency behavior that may allow the animal to escape hypoxia.

Eggplant (Solanum melongena) infusion has a modest and transitory effect on hypercholesterolemic subjects

Eggplant (Solanum melongena) is consumed extensively in Brazil. It has been believed that infusion of a powdered preparation of the fruit may reduce serum cholesterol. However, there are few documented reports on its effects on cholesterol metabolism and its possible hypocholesterolemic effect has not been proved by well-controlled studies. The aim of the present study was to observe the effects of S. melongena on the serum cholesterol and triglycerides of 38 hypercholesterolemic human volunteers ingesting S. melongena infusion for five weeks. Thirty-eight hypercholesterolemic subjects receiving either S. melongena infusion (N = 19) or placebo (N = 19) participated in two clinical experiments in which the effect of S. melongena infusion was studied with (N = 16) or without (N = 38) dietary orientation. Total cholesterol and its fractions, triglycerides, and apolipoproteins A and B were measured in blood at the beginning of the experiment and three and five weeks thereafter. No differences were observed compared to control. Intraindividual analysis showed that S. melongena infusion significantly reduced the blood levels of total and LDL cholesterol and of apolipoprotein B. After dietary orientation, no intra- or intergroup differences were seen for any of the parameters analyzed. The results suggest that S. melongena infusion had a modest and transitory effect, which was not different from that obtained with standard orientation for dyslipidemia patients (diet and physical activities).