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1.
Int J Mol Sci ; 21(1)2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31861859

RESUMO

In primary ciliary dyskinesia (PCD) patients, Pseudomonas aeruginosa is a major opportunistic pathogen, frequently involved in chronic infections of the lower airways. Infections by this bacterial species correlates with a worsening clinical prognosis and recalcitrance to currently available therapeutics. The antimicrobial peptide, lin-SB056-1, in combination with the cation chelator ethylenediaminetetraacetic acid (EDTA), was previously demonstrated to be bactericidal against P. aeruginosa in an artificial sputum medium. The purpose of this study was to validate the anti-P. aeruginosa activity of such a combination in PCD sputum and to evaluate the in vitro anti-virulence effects of EDTA. In combination with EDTA, lin-SB056-1 was able to significantly reduce the load of endogenous P. aeruginosa ex vivo in the sputum of PCD patients. In addition, EDTA markedly reduced the production of relevant bacterial virulence factors (e.g., pyocyanin, proteases, LasA) in vitro by two representative mucoid strains of P. aeruginosa isolated from the sputum of PCD patients. These results indicate that the lin-SB056-1/EDTA combination may exert a dual antimicrobial and anti-virulence action against P. aeruginosa, suggesting a therapeutic potential against chronic airway infections sustained by this bacterium.

2.
Crit Care Med ; 47(12): e1041-e1042, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31738268
3.
Crit Care Med ; 47(8): e722-e723, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31305314
4.
Environ Sci Pollut Res Int ; 26(20): 20742-20752, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31104242

RESUMO

Although the increased production of nanoparticles (NPs) has raised extensive concerns about the potential toxic effects on aquatic organisms, as well as the increasing evidences which documented the impact of ocean acidification (OA) on the physiology and fitness of marine invertebrates, limited number of studies reported their combined toxic effects. For these reasons, in the present study, we investigated the physiological and biochemical responses of one of the most economically important bivalve species in the World, the Manila clam Ruditapes philippinarum, after the exposure to an environmnetally relevant concentration of carboxylated carbon nanotubes and predicted OA conditions. The results showed that the organisms were not only susceptible to NPs but also to seawater acidification. Different responses between low pH and NPs for most tested biomarkers were observed, both in terms of physiological (respiration rate) and biochemical responses (metabolic capacity, oxitative status and neurotoxicity). Acidified pH significantly decreased the respiration rate and metabolism and increased the energy reserves consumption. Moreover, increase of the oxidative damage was also detected under this condition confirming that the mechanism of enhanced toxicity in the organisms should be attributed to lower aggregation state with more suspended NPs in acidified seawater, indicating that seawater acidification significantly influenced the impact of the used NPs in the exposed organisms.


Assuntos
Bivalves/fisiologia , Ácidos Carboxílicos/toxicidade , Nanotubos de Carbono/toxicidade , Água do Mar/química , Poluentes Químicos da Água/toxicidade , Animais , Disponibilidade Biológica , Biomarcadores/metabolismo , Bivalves/efeitos dos fármacos , Bivalves/metabolismo , Ácidos Carboxílicos/química , Concentração de Íons de Hidrogênio , Nanotubos de Carbono/química , Estresse Oxidativo , Poluentes Químicos da Água/química
5.
Sci Total Environ ; 666: 1178-1187, 2019 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-30970483

RESUMO

Ocean acidification events are recognized as important drivers of change in biological systems. Particularly, the impacts of acidification are more severe in estuarine systems than in surface ocean due to their shallowness, low buffering capacity, low salinity and high organic matter from land drainage. Moreover, because they are transitional areas, estuaries can be seriously impacted by a vast number of anthropogenic activities and in the last decades, carbon nanomaterials (CNMs) are considered as emerging contaminants in these ecosystems. Considering all these evidences, chronic experiment was carried out, trying to understand the possible alteration on the chemical behaviour of two different CNMs (functionalized and pristine) in predicted climate change scenarios and consequently, how these alterations could modify the sensitivity of one the most common marine and estuarine organisms (the polychaeta Hediste diversicolor) assessing a set of biomarkers related to polychaetes oxidative status as well as the metabolic performance and neurotoxicity. Our results demonstrated that all enzymes worked together to counteract seawater acidification and CNMs, however oxidative stress in the exposed polychaetes to both CNMs, especially under ocean acidification conditions, was enhanced. In fact, although the antioxidant enzymes tried to cope as compensatory response of cellular defense systems against oxidative stress, the synergistic interactive effects of pH and functionalized CNMs indicated that acidified pH significantly increased the oxidative damage (in terms of lipid peroxidation) in the cotaminated organisms. Different responses were observed in organisms submitted to pristine CNMs under pH control, where the lipid peroxidation did not increase along with the increasing exposure concentrations. The present results further demonstrated neurotoxicity caused by both CNMs, especially noticeable at acidified conditions. The mechanism of enhanced toxicity could be attributed to slighter aggregation and more suspended NMs in acidified seawater (as demonstrated by the DLS analysis). Therefore, ocean acidification may cause a higher risk of CNMs to marine ecosystems.


Assuntos
Nanotubos de Carbono/toxicidade , Neurotoxinas/toxicidade , Poliquetos/efeitos dos fármacos , Água do Mar/química , Poluentes Químicos da Água/toxicidade , Animais , Biomarcadores/metabolismo , Concentração de Íons de Hidrogênio , Estresse Oxidativo , Poliquetos/fisiologia , Portugal
6.
Crit Care Med ; 47(5): e432-e433, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30985468
7.
Artigo em Inglês | MEDLINE | ID: mdl-30797982

RESUMO

The widespread use of Carbon nanotubes (CNTs) has been increasing exponentially, leading to a significant potential release into the environment. Nevertheless, the toxic effects of CNTs in natural aquatic systems are related to their ability to interact with abiotic compounds. Considering that salinity variations are one of the main challenges in the environment and thus may influence the behavior and toxicity of CNTs, a laboratory experiment was performed exposing the tube-building polychaete Diopatra neapolitana (Delle Chiaje 1841) for 28 days to pristine multi-walled carbon nanotube (MWCNTs) and carboxylated MWCNTs, maintained at control salinity 28 and low salinity 21. An innovative approach based on thermogravimetric analysis (TGA) was adopted for the first time to assess the presence of MWCNTs aggregates in the organisms. Both CNTs generated toxic impacts in terms of regenerative capacity, energy reserves and metabolic capacity as well as oxidative and neuro status, however greater toxic impacts were observed in polychaetes exposed to carboxylated MWCNTs. Moreover, both CNTs maintained under control salinity (28) generated higher toxic impacts in the polychaetes compared to individuals maintained under low salinity (21), indicating that exposed polychaetes tend to be more sensitive to the alteration induced by salinity variations on the chemical behavior of both MWCNTs in comparison to salt stress.


Assuntos
Mudança Climática , Nanotubos de Carbono/toxicidade , Poliquetos/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Estresse Oxidativo , Termogravimetria , Poluentes Químicos da Água/química
8.
Mar Environ Res ; 145: 11-21, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30771907

RESUMO

With the increased production and research on nanoparticles, the presence of carbon nanotubes (CNTs) in aquatic systems is very likely to increase. Although it has been shown that CNTs may cause toxicity in marine organisms, to our knowledge, the possible impacts under global temperature increase is still unknown. For this reason, biochemical and physiological impacts induced in Mytilus galloprovincialis due to the presence of functionalized multi-walled CNTs (f-MWCNTs) and increased temperature were investigated in the present study. The mussels exposed to increased temperature alone presented higher metabolic capacity and expenditure of glycogen as an energy resource to fuel up defense mechanisms and thus preventing oxidative damage. Contrarily, organisms exposed to f-MWCNTs alone seemed not stressed enough to demonstrate differences in the metabolism capacity. Furthermore, f-MWCNTs seemed not able to significantly activate their antioxidant and biotransformation enzymes, which in turn may led to oxidative damage in the cells especially when organisms were exposed to a warmer temperature. In fact, at higher temperature, the antioxidant response of organisms exposed to f-MWCNTs was not effective and oxidative damage levels were observed. Nevertheless, no additive or synergetic effects were observed when mussels were exposed to both stressors simultaneously.

9.
Ann Intensive Care ; 9(1): 20, 2019 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-30701448

RESUMO

BACKGROUND: Vasopressors are commonly applied to restore and maintain blood pressure in patients with sepsis. We aimed to evaluate the current practice and therapeutic goals regarding vasopressor use in septic shock as a basis for future studies and to provide some recommendations on their use. METHODS: From November 2016 to April 2017, an anonymous web-based survey on the use of vasoactive drugs was accessible to members of the European Society of Intensive Care Medicine (ESICM). A total of 17 questions focused on the profile of respondents, triggering factors, first choice agent, dosing, timing, targets, additional treatments, and effects of vasopressors. We investigated whether the answers complied with current guidelines. In addition, a group of 34 international ESICM experts was asked to formulate recommendations for the use of vasopressors based on 6 questions with sub-questions (total 14). RESULTS: A total of 839 physicians from 82 countries (65% main specialty/activity intensive care) responded. The main trigger for vasopressor use was an insufficient mean arterial pressure (MAP) response to initial fluid resuscitation (83%). The first-line vasopressor was norepinephrine (97%), targeting predominantly a MAP > 60-65 mmHg (70%), with higher targets in patients with chronic arterial hypertension (79%). The experts agreed on 10 recommendations, 9 of which were based on unanimous or strong (≥ 80%) agreement. They recommended not to delay vasopressor treatment until fluid resuscitation is completed but rather to start with norepinephrine early to achieve a target MAP of ≥ 65 mmHg. CONCLUSION: Reported vasopressor use in septic shock is compliant with contemporary guidelines. Future studies should focus on individualized treatment targets including earlier use of vasopressors.

10.
Shock ; 51(2): 247-255, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-29401137

RESUMO

BACKGROUND: Potassium-(K)-channel inhibitors may increase systemic vascular resistance in vasodilatory shock states. OBJECTIVE: The purpose of the present study was to compare the macro- and microvascular effects of the adenosine triphosphate-sensitive K-channel-(KATP)-inhibitor glipizide and the nonselective K-channel inhibitor tetraethylammonium (TEA) in ovine endotoxemic shock and septic shock in rats. DESIGN: Two randomized, controlled laboratory studies. ANIMALS: Thirty female sheep and 40 male Sprague Dawley rats. SETTING: Animal research facility INTERVENTION:: Systemic hemodynamics were analyzed in ovine endotoxemic shock with guideline-oriented supportive therapy. Sheep were allocated to three treatment groups for 12 h: glipizide 10 mg kg·h, TEA 8 mg kg·h, or 0.9% saline. The microvascular effects of each drug were evaluated in septic rats (cecal ligation and puncture model) receiving a 2-h infusion of each study drug: glipizide 20 mg kg·h; TEA 50 mg kg·h, or 0.9% saline, respectively, followed by intravital microscopy of villi microcirculation. RESULTS: Compared with the control group, glipizide infusion increased systemic vascular resistance index and decreased cardiac index and heart rate (HR) in sheep (P < 0.05), whereas TEA infusion decreased HR and resulted in a decreased survival time (P = 0.001). In rats, glipizide infusion resulted in an increase in mean arterial pressure and a decrease in HR compared with baseline measurement (P < 0.05) without relevant effects on the villi microcirculation. TEA decreased HR and decreased capillary perfusion of the villi microcirculation compared with the sham group (P = 0.002). CONCLUSIONS: Selective inhibition of KATP-channels in ovine endotoxemic shock with glipizide partially restored vasomotor tone without exerting harmful effects on intestinal microcirculation in septic shock in rats. On the contrary, nonselective K-channel inhibition with TEA showed deleterious effects in both models, including impaired microcirculation and decreased survival time. Future research on glipizide in vasodilatory shock may be warranted.

11.
Crit Care Med ; 47(2): e89-e95, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30394918

RESUMO

OBJECTIVES: Propofol-based sedation may increase hemodynamic instability by decreasing vascular tone and venous return. Incremental exogenous catecholamines doses may be required to counteract such effects, aggravating the deleterious effects of sympathetic overstimulation. α-2 adrenergic agonists have been reported to decrease norepinephrine requirements in experimental septic shock. The aim of the present study is to test the hypothesis that switching from sedation with propofol to the α-2 agonist dexmedetomidine may decrease norepinephrine doses in septic shock. DESIGN: Prospective open-label crossover study. SETTINGS: University hospital, ICU. PATIENTS: Thirty-eight septic shock patients requiring norepinephrine to maintain adequate mean arterial pressure and needing deep sedation with propofol and remifentanil to maintain a Richmond Agitation-Sedation Scale score between -3 and -4. INTERVENTIONS: An initial set of measurements including hemodynamics, norepinephrine doses, and depth of sedation were obtained during sedation with propofol. Propofol was then replaced by dexmedetomidine and a second set of data was obtained after 4 hours of dexmedetomidine infusion. Sedation was switched back to propofol, and a final set of measurements was obtained after 8 hours. A Richmond Agitation-Sedation Scale score between -3 and -4 was maintained during the study period. MEASUREMENTS AND MAIN RESULTS: Norepinephrine requirements decreased from 0.69 ± 0.72 µg/kg/min before dexmedetomidine to 0.30 ± 0.25 µg/kg/min 4 hours after dexmedetomidine infusion, increasing again to 0.42 ± 0.36 µg/kg/min while on propofol 8 hours after stopping dexmedetomidine (p < 0.005). Dexmedetomidine dosage was 0.7 ± 0.2 µg/kg/hr. Before and after dexmedetomidine infusion, sedative doses remained unchanged (propofol 2.6 ± 1.2 vs 2.6 ± 1.2 mg/kg/hr; p = 0.23 and remifentanil 1.27 ± 0.17 vs 1.27 ± 0.16 µg/kg/hr; p = 0.52, respectively). Richmond Agitation-Sedation Scale was -4 (-4 to -3) before, -4 (-4 to -3) during, and -4 (-4 to -4) after dexmedetomidine (p = 0.07). CONCLUSIONS: For a comparable level of sedation, switching from propofol to dexmedetomidine resulted in a reduction of catecholamine requirements in septic shock patients.


Assuntos
Agonistas alfa-Adrenérgicos/uso terapêutico , Sedação Profunda/métodos , Dexmedetomidina/uso terapêutico , Hipnóticos e Sedativos/uso terapêutico , Norepinefrina/uso terapêutico , Propofol/uso terapêutico , Choque Séptico/tratamento farmacológico , Equilíbrio Ácido-Base/efeitos dos fármacos , Agonistas alfa-Adrenérgicos/administração & dosagem , Estudos Cross-Over , Feminino , Hemodinâmica/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , Norepinefrina/administração & dosagem , Choque Séptico/fisiopatologia
12.
Carbohydr Polym ; 203: 310-321, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30318218

RESUMO

Silver nanoparticles (AgNPs) have been intensively investigated in virtue of their optical and antimicrobial properties, although their applications have been limited due to inherent toxicity and to the need of employing harsh chemical reagents for the synthesis. In this work, ulvan, a sulfated polysaccharide extracted from green algae belonging to Ulva armoricana sp., was for the first time investigated and identified as reducing and stabilizing agent for AgNPs synthesis by using milder conditions than those conventionally adopted by chemical methods. The synthesized AgNPs were thoroughly characterized to highlight the structure and the role exerted by ulvan in their synthesis and stabilization. The formation of AgNPs stabilized by a thick ulvan shell was assessed by UV-vis, XRD, TEM, DLS and zeta potential analyses. The developed Ulvan based AgNps showed an IC50 in the range of 10 µg/ml in Balb/3T3 mouse embryo fibroblasts and antimicrobial activity toward both Gram + and Gram - bacteria.

13.
Mar Environ Res ; 143: 1-9, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30420134

RESUMO

In recent years, oxidative stress has been recognized as one of the most common effects of nanoparticles in different organisms. Ficopomatus enigmaticus (Fauvel, 1923), a member of a large family of serpulidae polychates, is an important encrusting organism in a diverse set of marine habitats, from harbours to coral reefs. This species has been previously studied for ecotoxicological purposes, despite the lack of reported studies on this species biochemical response after exposure to different pollutants. For these reasons, and for the first time, a set of biomarkers related to oxidative status were assessed in polychaetes after 28 days of exposure. Furthermore, polychaetes metabolic performance and potential neurotoxicity were investigated. Results clearly demonstrated induced toxicity in the filter-feeder polychaetes after exposure to nanoparticles. Indeed, CNTs altered the biochemical and physiological status of F. enigmaticus, both in terms of energy reserves (reduction of protein and glycogen contents), oxidative status (expressed as damage in cell function such as protein carbonyl content and lipid peroxidation) and activation of antioxidant enzymes defences (Glutathione reductase, Catalase, Glutathione peroxidase and Glutathione S-transferases activities). The present study showed for the first time that this species can be used as a model organism for nanoparticle toxicology.

14.
Ann Transl Med ; 6(20): 400, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30498727

RESUMO

Background: There is clear evidence that early causal therapy improves outcome in sepsis and septic shock, whereas recent studies on supportive hemodynamic therapy have produced very conflictive results. The objective of the present study was to determine whether a supportive hemodynamic therapy guided by clinically relevant invasive monitoring improves survival and organ function in a high-lethality model of septic shock in sheep as compared to sole causal therapy including surgical and antimicrobial treatment. Methods: Twenty healthy ewes were anaesthetized and instrumented for hemodynamic surveillance. After laparotomy and fecal withdrawal from the caecum, animals were randomly assigned to one of four groups: sham, control, causal and combined therapy. In all groups but the sham group, feces were injected into the peritoneal cavity. Septic shock was defined as mean arterial pressure (MAP) ≤60 mmHg and arterial lactate concentration ≥1.8 mmol·L-1. Animals of the control group received no therapy, while the causal group received broad-spectrum antibiotic therapy and peritoneal lavage. The combined therapy group received causal therapy plus supportive hemodynamic therapy. Results: The sham animals showed no signs of systemic infection, while all other animals developed septic shock with arterial hypotension and lactic acidosis within 4.0 (4.0-6.8) hours. Induction of causal therapy did not impact on haemodynamics as compared to the control group. Notably, 50% of the control animals and none of the causal therapy animals survived the study. Combined therapy stabilized haemodynamics and improved organ function and survival as compared to control and causal therapy groups. Conclusions: The present data suggest that sole causal sepsis therapy without hemodynamic support worsens outcome even more than natural evolution of sepsis and combined causal and supportive therapy. This underlines the importance of early hemodynamic stabilization in parallel with antibiotic and surgical treatment of the sepsis focus.

15.
Trials ; 19(1): 637, 2018 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-30454042

RESUMO

BACKGROUND: In patients with septic shock, the presence of an elevated heart rate (HR) after fluid resuscitation marks a subgroup of patients with a particularly poor prognosis. Several studies have shown that HR control in this population is safe and can potentially improve outcomes. However, all were conducted in a single-center setting. The aim of this multicenter study is to demonstrate that administration of the highly beta1-selective and ultrashort-acting beta blocker landiolol in patients with septic shock and persistent tachycardia (HR ≥ 95 beats per minute [bpm]) is effective in reducing and maintaining HR without increasing vasopressor requirements. METHODS: A phase IV, multicenter, prospective, randomized, open-label, controlled study is being conducted. The study will enroll a total of 200 patients with septic shock as defined by The Third International Consensus Definitions for Sepsis and Septic Shock criteria and tachycardia (HR ≥ 95 bpm) despite a hemodynamic optimization period of 24-36 h. Patients are randomized (1:1) to receive either standard treatment (according to the Surviving Sepsis Campaign Guidelines 2016) and continuous landiolol infusion to reach a target HR of 80-94 bpm or standard treatment alone. The primary endpoint is HR response (HR 80-94 bpm), the maintenance thereof, and the absence of increased vasopressor requirements during the first 24 h after initiating treatment. DISCUSSION: Despite recent studies, the role of beta blockers in the treatment of patients with septic shock remains unclear. This study will investigate whether HR control using landiolol is safe, feasible, and effective, and further enhance the understanding of beta blockade in patients with septic shock. TRIAL REGISTRATION: EU Clinical Trials Register; EudraCT, 2017-002138-22 . Registered on 8 August 2017.


Assuntos
Antagonistas Adrenérgicos beta/uso terapêutico , Antiarrítmicos/uso terapêutico , Frequência Cardíaca/efeitos dos fármacos , Unidades de Terapia Intensiva , Morfolinas/uso terapêutico , Choque Séptico/tratamento farmacológico , Ureia/análogos & derivados , Antagonistas Adrenérgicos beta/efeitos adversos , Antiarrítmicos/efeitos adversos , Pressão Sanguínea/efeitos dos fármacos , Ensaios Clínicos Fase IV como Assunto , Europa (Continente) , Humanos , Morfolinas/efeitos adversos , Estudos Multicêntricos como Assunto , Estudos Prospectivos , Ensaios Clínicos Controlados Aleatórios como Assunto , Choque Séptico/diagnóstico , Choque Séptico/fisiopatologia , Fatores de Tempo , Resultado do Tratamento , Ureia/efeitos adversos , Ureia/uso terapêutico , Vasoconstritores/uso terapêutico
16.
Microcirculation ; 25(8): e12505, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30192423

RESUMO

OBJECTIVE: The aim of the current study was to compare a newly developed web-based freely accessible software program for manual analysis of the microcirculation, the Capillary Mapper (CM), with AVA 3.2 software (AVA; MicroVision Medical B.V., Amsterdam, The Netherlands), which is the current gold standard for analysis of microcirculation videos. METHODS: A web-based software program was developed, which enables manual analysis of videos of the microcirculation to be carried out according to recommendations of the 2018 consensus conference. A set of 50 high quality microcirculation videos was analyzed with AVA and CM with respect to total vessel density, perfused vessel density, proportion of perfused vessels, and the microvascular flow index. RESULTS: Comparison of the mean values derived from manual analysis with CM and AVA revealed no significant differences in microcirculatory variables. Analysis according to Bland and Altman revealed an acceptable bias between manual analysis with the CM and AVA for all variables tested with sufficient limits of agreement. The analysis of intraclass correlation showed "excellent" agreement for all microcirculatory variables analyzed. CONCLUSIONS: The newly developed CM was successfully validated for manual analyses of microcirculation videos against the current gold standard, the software AVA 3.2.


Assuntos
Microcirculação , Gravação de Videoteipe , Viés , Velocidade do Fluxo Sanguíneo , Capilares , Humanos , Internet , Software
17.
Eur Heart J Suppl ; 20(Suppl A): A15-A18, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30188960

RESUMO

Landiolol is an injectable ultrashort acting beta-blocker with high beta1 selectivity indicated for heart rate control of atrial fibrillation in the emergency and critical care setting. Accordingly, landiolol is associated with a significantly reduced risk of arterial hypotension and negative inotropic effects. Based on this particular profile along with the clinical experience in Japan for more than a decade landiolol represents a promising agent for the management of elevated heart rate and atrial fibrillation in intensive care patients even with catecholamine requirements. This article provides a review and perspective of landiolol for heart rate control in intensive care patients based on the current literature.

18.
Mar Environ Res ; 141: 186-195, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30201273

RESUMO

Salinity plays a fundamental role in naturally fluctuating environments such as estuaries influencing physiological and biochemical performance of inhabiting biota. Moreover salinity is considered one of the main factors influencing nanoparticles' stability. Thus, the aim of the present paper was to show the impacts induced by different salinities (control-28 and 21) on the chemical behavior of water dispersible multi-walled carbon nanotube (MWCNTs-COOH) and the consequent toxicity in the common ragworm Hediste diversicolor, after long term exposure. Results showed a concentration-dependent toxicity in terms of energy reserves and metabolism, oxidative status and neurotoxicity. In addition, under low salinity (21), the toxicity of the carbon NMs was similar to the impacts measured under control (28), although under salinity 28 the concentrations of MWCNTs-COOH used generated greater alterations in LPO levels and antioxidant enzymes (SOD and GPx). These results demonstrate that higher salinity caused the formation of large-size aggregates, which increased the chance of physical retention, such as gravitational sedimentation, interception and straining of f-MWCNTs generating higher cell injuries than the impacts induced in polychaetes sensitivity to these contaminates due to low salinity.

19.
Aquat Toxicol ; 202: 163-172, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30048902

RESUMO

Intertidal species are frequently exposed to environmental changes associated with multiple stressors, which they must either avoid or tolerate by developing physiological and biochemical strategies. Some of the natural environmental changes are related with the tidal cycle which forces organisms to tolerate the differences between an aquatic and an aerial environment. Furthermore, in these environments, organisms are also subjected to pollutants from anthropogenic sources. The present study evaluated the impacts in Mytilus galloprovincialis exposed to multi-walled carbon nanotubes (0.01 mg/L MWCNTs) when continuously submersed or exposed to tides (5 h of low tide, 7 h of high tide) for 14 days. Our results demonstrated that mussels were physiologically and biochemically affected by MWCNTs, especially when exposed to tides. In fact, when only exposed to the carbon nanoparticles or only exposed to tides, the stress induced was not enough to activate mussels' antioxidant defenses which resulted in oxidative damage. However, when mussels were exposed to the combination of tides and MWCNTs increased metabolism was observed, associated with a possible higher production of reactive oxygen species (ROS), leading to a significant increase in the activities of antioxidant enzymes (superoxide dismutase, SOD and glutathione peroxide, GPx) and oxidized glutathione content (GSSG), preventing the occurrence of cellular damage, expressed as no lipid peroxidation (LPO) or protein carbonylation (PC). Therefore, organisms seemed to be able to tolerate MWCNTs and air exposure during tidal regime; however, the combination of both stressors induced higher oxidative stress. These findings indicate that the increasing presence of carbon nanoparticles in marine ecosystems can induce higher toxic impacts in intertidal organisms compared to organisms continuously submerged. Also, our results may indicate that air exposure can act as a cofounding factor on the assessment of different stressors in organisms living in coastal systems.


Assuntos
Mytilus/efeitos dos fármacos , Nanotubos de Carbono/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Antioxidantes/metabolismo , Ecossistema , Glutationa/metabolismo , Mytilus/crescimento & desenvolvimento , Mytilus/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/metabolismo
20.
Sci Rep ; 8(1): 8571, 2018 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-29872071

RESUMO

Salinity shifts in estuarine and coastal areas are becoming a topic of concern and are one of the main factors influencing nanoparticles behaviour in the environment. For this reason, the impacts of multi-walled carbon nanotubes (MWCNTs) under different seawater salinity conditions were evaluated on the common ragworm Hediste diversicolor, a polychaete species widely used as bioindicator of estuarine environmental quality. An innovative method to assess the presence of MWCNT aggregates in the sediments was used for the first time. Biomarkers approach was used to evaluate the metabolic capacity, oxidative status and neurotoxicity of polychaetes after long-term exposure. The results revealed an alteration of energy-related responses in contaminated polychaetes under both salinity conditions, resulting in an increase of metabolism and expenditure of their energy reserves (lower glycogen and protein contents). Moreover, a concentration-dependent toxicity (higher lipid peroxidation, lower ratio between reduced and oxidized glutathione and activation of antioxidant defences and biotransformation mechanisms) was observed in H. diversicolor, especially when exposed to low salinity. Additionally, neurotoxicity was observed by inhibition of Cholinesterases activity in organisms exposed to MWCNTs at both salinities.


Assuntos
Monitoramento Ambiental/métodos , Nanotubos de Carbono/química , Poliquetos/fisiologia , Salinidade , Água do Mar/química , Animais , Antioxidantes/metabolismo , Metabolismo Energético/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos dos fármacos , Oxirredução/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Poliquetos/efeitos dos fármacos , Poliquetos/metabolismo , Poluentes Químicos da Água/toxicidade
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