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2.
J Environ Manage ; 276: 111368, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32942219

RESUMO

The increasing presence of freshwater toxins have brought new challenges to preserve water quality due to their potential impact on the environment and human health. Two commonly occurring cyanotoxins, microcystin-LR and cylindrospermopsin, with different physico-chemical properties were used to evaluate the efficiency of photocatalysis using a continuous-flow reactor with immobilized TiO2 on glass tubes and UV-A light. The effect of flow rate and hydrogen peroxide addition on the efficiency of cyanotoxin removal were evaluated. An analysis of the effects on microcystin-LR removal efficiency showed that low flow rates (1 mL/min) and high H2O2 concentrations (120 mg/L) were needed to provide effective degradation. Up to 27.9% and 39.1% removal of MC-LR and CYN, respectively were achieved by UV-A/TiO2 after a single pass through the reactor. A slight increase of the removal of both cyanotoxins was observed when they were in a mixture (35.5% of MC-LR and 51.3% of CYN). The addition of H2O2 to the UV/TiO2 system led to an average removal enhancement of 92.6% of MC-LR and of 29.5% of CYN compared to the UV/TiO2 system. Photolysis assisted by H2O2 degraded MC-LR by up to 77.7%. No significant removal (<10%) was observed by photolysis alone or physical adsorption. This study presents a proof-of-principle that demonstrates the feasibility for this technology to be integrated in large-scale applications.


Assuntos
Peróxido de Hidrogênio , Poluentes Químicos da Água , Toxinas Bacterianas , Microcistinas , Titânio , Uracila/análogos & derivados
4.
Lancet ; 396(10253): 759-769, 2020 09 12.
Artigo em Inglês | MEDLINE | ID: mdl-32871100

RESUMO

BACKGROUND: Cardiac muscle hypercontractility is a key pathophysiological abnormality in hypertrophic cardiomyopathy, and a major determinant of dynamic left ventricular outflow tract (LVOT) obstruction. Available pharmacological options for hypertrophic cardiomyopathy are inadequate or poorly tolerated and are not disease-specific. We aimed to assess the efficacy and safety of mavacamten, a first-in-class cardiac myosin inhibitor, in symptomatic obstructive hypertrophic cardiomyopathy. METHODS: In this phase 3, randomised, double-blind, placebo-controlled trial (EXPLORER-HCM) in 68 clinical cardiovascular centres in 13 countries, patients with hypertrophic cardiomyopathy with an LVOT gradient of 50 mm Hg or greater and New York Heart Association (NYHA) class II-III symptoms were assigned (1:1) to receive mavacamten (starting at 5 mg) or placebo for 30 weeks. Visits for assessment of patient status occurred every 2-4 weeks. Serial evaluations included echocardiogram, electrocardiogram, and blood collection for laboratory tests and mavacamten plasma concentration. The primary endpoint was a 1·5 mL/kg per min or greater increase in peak oxygen consumption (pVO2) and at least one NYHA class reduction or a 3·0 mL/kg per min or greater pVO2 increase without NYHA class worsening. Secondary endpoints assessed changes in post-exercise LVOT gradient, pVO2, NYHA class, Kansas City Cardiomyopathy Questionnaire-Clinical Summary Score (KCCQ-CSS), and Hypertrophic Cardiomyopathy Symptom Questionnaire Shortness-of-Breath subscore (HCMSQ-SoB). This study is registered with ClinicalTrials.gov, NCT03470545. FINDINGS: Between May 30, 2018, and July 12, 2019, 429 adults were assessed for eligibility, of whom 251 (59%) were enrolled and randomly assigned to mavacamten (n=123 [49%]) or placebo (n=128 [51%]). 45 (37%) of 123 patients on mavacamten versus 22 (17%) of 128 on placebo met the primary endpoint (difference +19·4%, 95% CI 8·7 to 30·1; p=0·0005). Patients on mavacamten had greater reductions than those on placebo in post-exercise LVOT gradient (-36 mm Hg, 95% CI -43·2 to -28·1; p<0·0001), greater increase in pVO2 (+1·4 mL/kg per min, 0·6 to 2·1; p=0·0006), and improved symptom scores (KCCQ-CSS +9·1, 5·5 to 12·7; HCMSQ-SoB -1·8, -2·4 to -1·2; p<0·0001). 34% more patients in the mavacamten group improved by at least one NYHA class (80 of 123 patients in the mavacamten group vs 40 of 128 patients in the placebo group; 95% CI 22·2 to 45·4; p<0·0001). Safety and tolerability were similar to placebo. Treatment-emergent adverse events were generally mild. One patient died by sudden death in the placebo group. INTERPRETATION: Treatment with mavacamten improved exercise capacity, LVOT obstruction, NYHA functional class, and health status in patients with obstructive hypertrophic cardiomyopathy. The results of this pivotal trial highlight the benefits of disease-specific treatment for this condition. FUNDING: MyoKardia.


Assuntos
Benzilaminas/uso terapêutico , Miosinas Cardíacas/antagonistas & inibidores , Cardiomiopatia Hipertrófica/tratamento farmacológico , Uracila/análogos & derivados , Antagonistas Adrenérgicos beta/uso terapêutico , Idoso , Benzilaminas/efeitos adversos , Bloqueadores dos Canais de Cálcio/uso terapêutico , Cardiomiopatia Hipertrófica/fisiopatologia , Fármacos Cardiovasculares/uso terapêutico , Método Duplo-Cego , Tolerância ao Exercício/fisiologia , Feminino , Hemodinâmica/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Consumo de Oxigênio/fisiologia , Avaliação de Resultados da Assistência ao Paciente , Uracila/efeitos adversos , Uracila/uso terapêutico
5.
PLoS One ; 15(8): e0237162, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32750098

RESUMO

Viral diversity is an important feature of hepatitis C virus (HCV) infection and an important predictor of disease progression and treatment response. HIV/HCV co-infection is associated with enhanced HCV replication, increased fibrosis, and the development of liver disease. HIV also increases quasispecies diversity of HCV structural genes, although limited data are available regarding the impact of HIV on non-structural genes of HCV, particularly in the absence of direct-acting therapies. The genetic diversity and presence of drug resistance mutations within the RNA-dependent RNA polymerase (NS5B) gene were examined in 3 groups of women with HCV genotype 1a infection, including those with HCV mono-infection, antiretroviral (ART)-naïve women with HIV/HCV co-infection and CD4 cell count <350 cells/mm3, and ART-naïve women with HIV/HCV co-infection and CD4 cell count ≥350 cells/mm3. None had ever been treated for HCV infection. There was evidence of significant diversity across the entire NS5B gene in all women. There were several nucleotides and amino acids with distinct distributions across the three study groups, although no obvious clustering of NS5B sequences was observed based on HIV co-infection or CD4 cell count. Polymorphisms at amino acid positions associated with resistance to dasabuvir and sofosbuvir were limited, although the Q309R variant associated with ribavirin resistance was present in 12 individuals with HCV mono-infection, 8 HIV/HCV co-infected individuals with CD4 <350 cells/mm3, and 12 HIV/HCV co-infected individuals with CD4 ≥350 cells/mm3. Previously reported fitness altering mutations were rare. CD8+ T cell responses against the human leukocyte antigen (HLA) B57-restricted epitopes NS5B2629-2637 and NS5B2936-2944 are critical for HCV control and were completely conserved in 44 (51.8%) and 70 (82.4%) study participants. These data demonstrate extensive variation across the NS5B gene. Genotypic variation may have a profound impact on HCV replication and pathogenesis and deserves careful evaluation.


Assuntos
Infecções Oportunistas Relacionadas com a AIDS/genética , Coinfecção/genética , Variação Genética , HIV , Hepacivirus/genética , Hepatite C/genética , Proteínas não Estruturais Virais/genética , Infecções Oportunistas Relacionadas com a AIDS/tratamento farmacológico , Infecções Oportunistas Relacionadas com a AIDS/virologia , Adulto , Sequência de Aminoácidos , Antivirais/uso terapêutico , Contagem de Linfócito CD4 , Estudos de Coortes , Coinfecção/tratamento farmacológico , Coinfecção/virologia , Farmacorresistência Viral/genética , Feminino , Genótipo , Hepatite C/tratamento farmacológico , Hepatite C/virologia , Humanos , Filogenia , RNA Replicase/genética , RNA Viral/genética , RNA Viral/isolamento & purificação , Sofosbuvir/uso terapêutico , Sulfonamidas/uso terapêutico , Uracila/análogos & derivados , Uracila/uso terapêutico
6.
Environ Pollut ; 266(Pt 2): 115423, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32829127

RESUMO

Cylindrospermopsin (CYN) is an important cyanobacterial toxin posing a major threat to surface waters during cyanobacterial blooms. Hence, methods for cyanotoxin removal are required to confront seasonal or local incidences to sustain the safety of potable water reservoirs. Non-thermal plasmas provide the possibility for an environmentally benign treatment which can be adapted to specific concentrations and environmental conditions without the need of additional chemicals. We therefore investigated the potential of two different non-thermal plasma approaches for CYN degradation, operated either in a water mist, i.e. in air, or submerged in water. A degradation efficacy of 0.03 ± 0.00 g kWh-1 L-1 was found for a dielectric barrier discharge (DBD) operated in air, while a submerged pulsed corona-like discharge resulted in an efficacy of 0.24 ± 0.02 g kWh-1 L-1. CYN degradation followed a pseudo zeroth order or pseudo first order reaction kinetic, respectively. Treatment efficacy of the corona-like discharge submerged in water increased with pH values of the initial solution changing from 5.0 to 7.5. Notably, a pH-depending residual oxidative effect was observed for the submerged discharge, resulting in ongoing CYN degradation, even without further plasma treatment. In this case hydroxyl radicals were identified as the dominant oxidants of CYN at acidic pH values. In comparison, degradation by the DBD could be related primarily to the generation of ozone.


Assuntos
Cianobactérias , Ozônio , Poluentes Químicos da Água , Toxinas Bacterianas , Radical Hidroxila , Uracila/análogos & derivados
7.
Environ Sci Technol ; 54(16): 10118-10127, 2020 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-32693577

RESUMO

Cylindrospermopsin (CYN) is one of the most important cyanobacterial toxins frequently found in surface waters. We reported the detailed kinetics and pathways for the reaction of CYN with carbonate radicals (CO3•-). The rate constants of neutral and deprotonated CYN with CO3•- were found to be (1.2 ± 0.7) × 107 M-1 s-1 and (3.0 ± 0.4) × 108 M-1 s-1, respectively. The transformation products for the oxidation of CYN by CO3•- were identified by high-resolution mass spectrometry, illustrating that the guanidine and bridged hydroxyl portions were the primary moieties attacked by CO3•-. Thus, three transformation pathways, including cleavage of the hydroxymethyluracil moiety, hydroxylation, and oxidation of the bridged hydroxyl group, are proposed for the CO3•- oxidation of CYN. Moreover, this study reported that dissolved organic matter (DOM) reduced the transformation rate of CYN by inhibiting the transformation of oxidation intermediates. Finally, the role of CO3•- in CYN degradation was estimated in both sunlit surface waters and advanced oxidation processes (AOPs), demonstrating that CO3•- played an important role in CYN attenuation under nonacidic environmentally relevant conditions. The kinetic parameters and product information obtained in this study will be of considerable interest for the application of AOPs and predicting the environmental fate of CYN.


Assuntos
Carbonatos , Uracila , Toxinas Bacterianas , Cinética , Oxirredução , Uracila/análogos & derivados
8.
J Cancer Res Clin Oncol ; 146(10): 2575-2587, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32715436

RESUMO

BACKGROUND: Limited treatment options are available in chemotherapy-refractory metastatic colorectal cancer (mCRC). The objective was to conduct a systematic literature review (SLR) and exploratory network meta-analysis (NMA) to compare the tolerability and effectiveness of SIRT with Y-90 resin microspheres, regorafenib, TAS-102 (trifluridine/tipiracil), and best supportive care (BSC) as third-line treatment in patients with mCRC. METHODS: An SLR was conducted to identify studies comparing two or more of the treatments and reporting overall survival (OS), progression-free survival, tumor response, or adverse event (AE) incidence. An exploratory NMA was conducted to compare hazard ratios (HRs) for OS using Markov chain Monte Carlo (MCMC) techniques. RESULTS: Seven studies were identified in the SLR: two double-blind randomized-controlled trials (RCT) for each drug, one open-label RCT, and two non-randomized comparative studies for SIRT. Patient selection criteria differed between studies, with SIRT studies including patients with liver-dominant colorectal metastases. Nausea and vomiting were more frequent with TAS-102 than regorafenib or SIRT; diarrhea was more common with TAS-102 and regorafenib than SIRT. The exploratory NMA suggested that all active treatments improved OS, with HRs of 0.48 (95% CrI 0.30-0.78) for SIRT with Y-90 resin microspheres, 0.63 (0.38-1.03) for TAS-102, and 0.67 (0.40-1.08) for regorafenib each compared to BSC. CONCLUSIONS: Regorafenib, TAS-102 and SIRT using Y-90 resin microspheres are more effective than BSC in third-line treatment of mCRC; however, study heterogeneity made comparisons between active treatments challenging. SIRT is a viable treatment for third-line mCRC and its favorable AE profile should be considered in the therapeutic decision-making process.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Braquiterapia/métodos , Neoplasias Colorretais/dietoterapia , Neoplasias Colorretais/radioterapia , Compostos de Fenilureia/uso terapêutico , Piridinas/uso terapêutico , Pirrolidinas/uso terapêutico , Trifluridina/uso terapêutico , Uracila/análogos & derivados , Radioisótopos de Ítrio/administração & dosagem , Método Duplo-Cego , Combinação de Medicamentos , Humanos , Microesferas , Metástase Neoplásica , Metanálise em Rede , Cuidados Paliativos/métodos , Compostos de Fenilureia/administração & dosagem , Intervalo Livre de Progressão , Piridinas/administração & dosagem , Pirrolidinas/administração & dosagem , Ensaios Clínicos Controlados Aleatórios como Assunto , Trifluridina/administração & dosagem , Uracila/administração & dosagem , Uracila/uso terapêutico
9.
Anticancer Res ; 40(7): 4157-4163, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32620665

RESUMO

BACKGROUND/AIM: The efficacy of trifluridine/thymidine phosphorylase inhibitor (FTD/TPI) plus bevacizumab as later-line treatment for metastatic colorectal cancer (mCRC) has been demonstrated. However, little is known about the impact of a usage history of bevacizumab in front-line treatment on the clinical benefit of combining bevacizumab with FTD/TPI. PATIENTS AND METHODS: A total of 62 patients with mCRC treated with FTD/TPI±bevacizumab was enrolled and assessed for chemotherapeutic efficacy and adverse events. RESULTS: Regardless of the usage history of bevacizumab in front-line treatment, the FTD/TPI plus bevacizumab group had a significantly better progression-free survival rate than the FTD/TPI monotherapy group, and no significant differences in the safety profile were observed between the two groups. CONCLUSION: Combining bevacizumab with FTD/TPI improves the survival outcomes with manageable toxicity, regardless of the usage history of bevacizumab in front-line treatment, in patients with mCRC.


Assuntos
Inibidores da Angiogênese/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Bevacizumab/uso terapêutico , Neoplasias Colorretais/tratamento farmacológico , Pirrolidinas/uso terapêutico , Timidina Fosforilase/antagonistas & inibidores , Trifluridina/uso terapêutico , Uracila/análogos & derivados , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias Colorretais/mortalidade , Neoplasias Colorretais/patologia , Combinação de Medicamentos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Análise de Sobrevida , Uracila/uso terapêutico , Adulto Jovem
10.
Circ Heart Fail ; 13(6): e006853, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32498620

RESUMO

BACKGROUND: Obstructive hypertrophic cardiomyopathy (oHCM) is characterized by unexplained left ventricular (LV) hypertrophy associated with dynamic LV outflow tract obstruction. Current medical therapies are nonspecific and have limited efficacy in relieving symptoms. Mavacamten is a first-in-class targeted inhibitor of cardiac myosin, which has been shown to reduce LV outflow tract obstruction, improve exercise capacity, and relieve symptoms of oHCM in the PIONEER-HCM phase 2 study. METHODS: EXPLORER-HCM is a multicenter, phase 3, randomized, double-blind, placebo-controlled trial to investigate the efficacy and safety of mavacamten in treating symptomatic oHCM. Eligible adults with oHCM and New York Heart Association Functional Class II or III are randomized 1:1 to receive once-daily, oral mavacamten, or matching placebo for 30 weeks. The primary composite functional end point is clinical response at week 30 compared to baseline defined as either (1) an increase in peak oxygen consumption ≥1.5 mL/kg/min and reduction of at least one New York Heart Association class; or (2) an improvement of ≥3.0 mL/kg/min in peak oxygen consumption with no worsening of New York Heart Association class. Secondary end points include change in postexercise LV outflow tract gradient, New York Heart Association class, peak oxygen consumption, and patient-reported outcomes assessed by the Kansas City Cardiomyopathy Questionnaire and a novel HCM-specific instrument. Exploratory end points aim to characterize the effect of mavacamten on multiple aspects of oHCM pathophysiology. CONCLUSIONS: EXPLORER-HCM is a phase 3 trial in oHCM testing a first-in-class, targeted strategy of myosin inhibition to improve symptom burden and exercise capacity through reducing LV outflow tract obstruction. Results of this trial will provide evidence to support the first disease-specific treatment for HCM. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03470545.


Assuntos
Benzilaminas/uso terapêutico , Cardiomiopatia Hipertrófica/tratamento farmacológico , Fármacos Cardiovasculares/uso terapêutico , Uracila/análogos & derivados , Benzilaminas/efeitos adversos , Cardiomiopatia Hipertrófica/diagnóstico por imagem , Cardiomiopatia Hipertrófica/fisiopatologia , Fármacos Cardiovasculares/efeitos adversos , Ensaios Clínicos Fase III como Assunto , Método Duplo-Cego , Tolerância ao Exercício/efeitos dos fármacos , Humanos , Estudos Multicêntricos como Assunto , Ensaios Clínicos Controlados Aleatórios como Assunto , Recuperação de Função Fisiológica , Resultado do Tratamento , Uracila/efeitos adversos , Uracila/uso terapêutico , Função Ventricular Esquerda/efeitos dos fármacos
11.
PLoS One ; 15(6): e0234314, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32530932

RESUMO

Regorafenib (REG) and trifluridine/tipiracil (FTD/TPI) showed survival benefits in metastatic colorectal cancer patients previously treated with standard chemotherapies; therefore, we compared the efficacy and safety of these two treatments. Patients with metastatic colorectal cancer treated with REG or FTD/TPI as a salvage-line therapy from May 2014 to December 2017 were included. We retrospectively analyzed long-term survival, safety, and clinical outcomes. Among 134 patients, 57 and 77 received REG and FTD/TPI, respectively. The REG group received more prior systemic chemotherapies and significantly more frequent additional chemotherapies than the FTD/TPI group did. The median follow-up was 6.2 months, whereas the median overall survival was 9.9 and 11.4 months in the REG and FTD/TPI groups, respectively (hazard ratio = 0.954, p = 0.837). The median progression-free survival was 2.0 and 3.3 months in the REG and FTD/TPI groups, respectively (hazard ratio = 0.52, p = 0.00047), indicating significant differences, whereas the objective response and disease control rates did not differ. The median overall survival of patients with additional subsequent chemotherapies after disease progression was longer than that of patients without additional chemotherapy. The most frequent grade ≥3 adverse events were hypertension and neutropenia in the REG and FTD/TPI groups, respectively. Our study suggested that sequential use of both drugs may prolong survival.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica , Neoplasias Colorretais/tratamento farmacológico , Compostos de Fenilureia/uso terapêutico , Piridinas/uso terapêutico , Pirrolidinas/uso terapêutico , Trifluridina/uso terapêutico , Uracila/análogos & derivados , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias Colorretais/patologia , Combinação de Medicamentos , Resistencia a Medicamentos Antineoplásicos , Feminino , Humanos , Japão , Masculino , Pessoa de Meia-Idade , Intervalo Livre de Progressão , Estudos Retrospectivos , Terapia de Salvação , Resultado do Tratamento , Uracila/uso terapêutico
12.
Crit Rev Oncol Hematol ; 152: 102987, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32485527

RESUMO

TAS-102 is a preconstituted drug combination comprising an oral fluoropyrimidine (trifluridine, TFT) and a potent inhibitor of thymidine phosphorylase (tipiracil hydrochloride, TPI). TFT/TPI has recently received Food and Drug Administration (FDA) approval also for the treatment of gastric cancer after at least two lines of chemotherapy. The approval was based on a large phase 3 trial (TAGS), in which TAS-102 showed a 31 % decrease in the risk of death compared with placebo. Here, we review the pharmacological properties, clinical development and potential future directions of TAS-102 in gastric cancer.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Pirrolidinas/uso terapêutico , Neoplasias Gástricas , Trifluridina/uso terapêutico , Uracila/análogos & derivados , Fenômenos Bioquímicos , Combinação de Medicamentos , Humanos , Neoplasias Gástricas/tratamento farmacológico , Uracila/uso terapêutico
13.
Environ Pollut ; 265(Pt B): 114965, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32559695

RESUMO

Cylindrospermopsin (CYN) is an emerging cyanotoxin increasingly being found in freshwater cyanobacterial blooms worldwide. Humans and animals are exposed to CYN through the consumption of contaminated water and food as well as occupational and recreational water activities; therefore, it represents a potential health threat. It exhibits genotoxic effects in metabolically active test systems, thus it is considered as pro-genotoxic. In the present study, the advanced 3D cell model developed from human hepatocellular carcinoma (HepG2) cells was used for the evaluation of CYN cyto-/genotoxic activity. Spheroids were formed by forced floating method and were cultured for three days under static conditions prior to exposure to CYN (0.125, 0.25 and 0.5 µg/mL) for 72 h. CYN influence on spheroid growth was measured daily and cell survival was determined by MTS assay and live/dead staining. The influence on cell proliferation, cell cycle alterations and induction of DNA damage (γH2AX) was determined using flow cytometry. Further, the expression of selected genes (qPCR) involved in the metabolism of xenobiotics, proliferation, DNA damage response, apoptosis and oxidative stress was studied. Results revealed that CYN dose-dependently reduced the size of spheroids and affected cell division by arresting HepG2 cells in G1 phase of the cell cycle. No induction of DNA double strand breaks compared to control was determined at applied conditions. The analysis of gene expression revealed that CYN significantly deregulated genes encoding phase I (CYP1A1, CYP1A2, CYP3A4, ALDH3A) and II (NAT1, NAT2, SULT1B1, SULT1C2, UGT1A1, UGT2B7) enzymes as well as genes involved in cell proliferation (PCNA, TOP2α), apoptosis (BBC3) and DNA damage response (GADD45a, CDKN1A, ERCC4). The advanced 3D HepG2 cell model due to its more complex structure and improved cellular interactions provides more physiologically relevant information and more predictive data for human exposure, and can thus contribute to more reliable genotoxicity assessment of chemicals including cyanotoxins.


Assuntos
Arilamina N-Acetiltransferase , Neoplasias Hepáticas , Animais , Toxinas Bacterianas , Dano ao DNA , Células Hep G2 , Humanos , Toxinas Marinhas , Microcistinas , Uracila/análogos & derivados
14.
Sci Total Environ ; 738: 139807, 2020 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-32585507

RESUMO

Cylindrospermopsin (CYN), a cyanotoxin produced by harmful algal blooms, has been reported worldwide; however, there remains limited understanding of its potential risks to surface water quality. In the present study, we critically reviewed available literature regarding the global occurrence, bioaccumulation, and toxicity of CYN in aquatic systems with a particular focus on freshwater. We subsequently developed environmental exposure distributions (EEDs) for CYN in surface waters and performed probabilistic environmental hazard assessments (PEHAs) using guideline values (GVs). PEHAs were performed by geographic region, type of aquatic system, and matrix. CYN occurrence was prevalent in North America, Europe, and Asia/Pacific, with lakes being the most common system. Many global whole water EEDs exceeded guideline values (GV) previously developed for drinking water (e.g., 0.5 µg L-1) and recreational water (e.g., 1 µg L-1). GV exceedances were higher in the Asia/Pacific region, and in rivers and reservoirs. Rivers in the Asia/Pacific region exceeded the lowest drinking water GV 73.2% of the time. However, lack of standardized protocols used for analyses was alarming, which warrants improvement in future studies. In addition, bioaccumulation of CYN has been reported in mollusks, crustaceans, and fish, but such exposure information remains limited. Though several publications have reported aquatic toxicity of CYN, there is limited chronic aquatic toxicity data, especially for higher trophic level organisms. Most aquatic toxicity studies have not employed standardized experimental designs, failed to analytically verify treatment levels, and did not report purity of CYN used for experiments; therefore, existing data are insufficient to derive water quality guidelines. Considering such elevated exceedances of CYN in global surface waters and limited aquatic bioaccumulation and toxicity data, further aquatic monitoring, environmental fate and mechanistic toxicology studies are warranted to robustly assess and manage water quality risks to public health and the environment.


Assuntos
Bioacumulação , Animais , Ásia , Toxinas Bacterianas , Europa (Continente) , América do Norte , Uracila/análogos & derivados
15.
Phys Chem Chem Phys ; 22(21): 12120-12128, 2020 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-32440669

RESUMO

The photophysics of selenium-substituted nucleobases has attracted recent experimental attention because they could serve as potential photosensitizers in photodynamic therapy. Herein, we present a comprehensive MS-CASPT2 study on the spectroscopic and excited-state properties, and photophysics of 2-selenouracil (2SeU), 4-selenouracil (4SeU), and 2,4-selenouracil (24SeU). Relevant minima, conical intersections, crossing points, and excited-state relaxation paths in the lowest five electronic states (i.e., S0, S1, S2, T2, and T1) are explored. On the basis of these results, their photophysical mechanisms are proposed. Upon photoirradiation to the bright S2 state, 2SeU quickly relaxes to its S2 minimum and then moves in an essentially barrierless way to a nearby S2/S1 conical intersection near which the S1 state is populated. Next, the S1 system arrives at an S1/T2/T1 intersection where a large S1/T1 spin-orbit coupling of 430.8 cm-1 makes the T1 state populated. In this state, a barrier of 6.8 kcal mol-1 will trap 2SeU for a while. In parallel, for 4SeU or 24SeU, the system first relaxes to the S2 minimum and then overcomes a small barrier to approach an S2/S1 conical intersection. Once hopping to the S1 state, there exists an extended region with very close S1, T2, and T1 energies. Similarly, a large S1/T1 spin-orbit coupling of 426.8 cm-1 drives the S1→ T1 intersystem crossing process thereby making the T1 state populated. Similarly, an energy barrier heavily suppresses electronic transition to the S0 state. The present work manifests that different selenium substitutions on uracil can lead to a certain extent of different vertical and adiabatic excitation energies, excited-state properties, and relaxation pathways. These insights could help understand the photophysics of selenium-substituted nucleobases.


Assuntos
Compostos Organosselênicos/química , Uracila/análogos & derivados , Luz , Modelos Químicos , Estrutura Molecular , Compostos Organosselênicos/efeitos da radiação , Termodinâmica , Uracila/química , Uracila/efeitos da radiação
18.
Sci Total Environ ; 731: 139014, 2020 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-32428751

RESUMO

Analytical methods based on direct injection (DI) and solid phase extraction (SPE) coupled with ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC- MS/MS) were developed for the determination of anatoxin-a (ATX-a), cylindrospermopsin (CYN), and homoanatoxin-a (HATX-a) in freshwater samples impacted with cyanobacterial blooms. The presence of CYN in freshwater samples was detected and quantified based on direct injection method, while ATX-a and HATX-a could be determined by both DI and SPE-based methods. Matrix effects (ME) on the signal intensity of the cyanotoxins were systematically evaluated for both direct injection and SPE extract samples. CYN, ATX-a, and HATX-a suffered a significant suppression during UPLC-MS/MS. The selection of internal standards (ISs) for compensating/correcting the losses of target cyanotoxins during sample preparation and matrix effects in UPLC-MS/MS analyses were systematically evaluated. Acetaminophen-d4 (an isotopically labelled acetaminophen) is a suitable internal standard for correcting the ME on the signal intensity of ATX-a and HATX-a, while the use of L-phenylalanine-d5 or caffeine-d9 as IS for correcting ME of these toxins was not efficient, as expected. The method detection limit (MDL) for the target cyanotoxins ranged from 0.6 to 15 ng/L, which is sensitive enough to detect the presence of these toxins in cyanobacterial bloom freshwater. The developed methods were successfully applied for routine monitoring of the occurrence of these cyanotoxins in a local water body. Monitoring results depicted that ATX-a, CYN and HATX-a were ubiquitously detected in water samples, at concentrations ranging from 70 to 24,600 ng/L.


Assuntos
Extração em Fase Sólida , Espectrometria de Massas em Tandem , Toxinas Bacterianas , Compostos Bicíclicos Heterocíclicos com Pontes , Cromatografia Líquida , Água Doce/análise , Microcistinas , Tropanos , Uracila/análogos & derivados
19.
Gastroenterol Clin North Am ; 49(2): 253-277, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32389362

RESUMO

The World Health Organization has called for the elimination of hepatitis C virus (HCV) as a public health threat by 2030. Highly effective direct-acting antiviral agents provide the therapeutic tools required for elimination. In the absence of a vaccine, HCV elimination will require enhanced primary prevention and an increase in the proportions of people diagnosed and treated. Given that globally only 20% of people with chronic HCV are diagnosed, and around 5% have initiated HCV treatment, the task ahead is enormous. But, global public health needs optimism, and countries currently on track for HCV elimination provide a pathway forward.


Assuntos
Antivirais/administração & dosagem , Hepatite C Crônica/tratamento farmacológico , Hepatite C Crônica/prevenção & controle , Anilidas/administração & dosagem , Antivirais/economia , Benzofuranos/administração & dosagem , Carbamatos/administração & dosagem , Quimioterapia Combinada , Saúde Global , Custos de Cuidados de Saúde , Hepatite C Crônica/diagnóstico , Hepatite C Crônica/economia , Humanos , Imidazóis/administração & dosagem , Sofosbuvir/administração & dosagem , Sulfonamidas/administração & dosagem , Uracila/administração & dosagem , Uracila/análogos & derivados , Organização Mundial da Saúde
20.
Sci Total Environ ; 729: 138924, 2020 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-32361450

RESUMO

Cylindrospermopsin (CYN) is a toxic alkaloid highly persistent in aquatic environments. Biological removal of CYN was described previously. However, no transformation products formed by biological processes could be identified so far. Here, we describe that various manganese-oxidizing bacteria (MOB) transform CYN completely at an initial mean concentration of 7 mg L-1 (17 µM) within 3 to 34 days. Regardless of the strain, and transformation rate, transformation of CYN by MOB led to the same seven transformation products identified by mass spectrometry, which suggests that the removal of CYN by MOB follows a similar mechanism. Oxidation was the main transformation process, and the uracil moiety was the most susceptible part of the CYN molecule. In vitro cytotoxicity tests with the transformation products of CYN formed by one of the tested strains against the two human liver cell lines HepG2 and HepaRG, revealed that the transformation products were substantially less toxic than pure CYN for both cell lines. The results suggest that incubation with MOB might be an option for water treatment to remove CYN and may allow more detailed studies on the fate of CYN in the environment.


Assuntos
Bactérias , Toxinas Bacterianas , Humanos , Fígado , Manganês , Oxirredução , Uracila/análogos & derivados
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