Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 19 de 19
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
iScience ; 27(6): 110055, 2024 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-38868204

RESUMO

Humans can quickly adapt to recognize acoustically degraded speech, and here we hypothesize that the quick adaptation is enabled by internal linguistic feedback - Listeners use partially recognized sentences to adapt the mapping between acoustic features and phonetic labels. We test this hypothesis by quantifying how quickly humans adapt to degraded speech and analyzing whether the adaptation process can be simulated by adapting an automatic speech recognition (ASR) system based on its own speech recognition results. We consider three types of acoustic degradation, i.e., noise vocoding, time compression, and local time-reversal. The human speech recognition rate can increase by >20% after exposure to just a few acoustically degraded sentences. Critically, the ASR system with internal linguistic feedback can adapt to degraded speech with human-level speed and accuracy. These results suggest that self-supervised learning based on linguistic feedback is a plausible strategy for human adaptation to acoustically degraded speech.

2.
Elife ; 122023 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-38032825

RESUMO

The computational principles underlying attention allocation in complex goal-directed tasks remain elusive. Goal-directed reading, that is, reading a passage to answer a question in mind, is a common real-world task that strongly engages attention. Here, we investigate what computational models can explain attention distribution in this complex task. We show that the reading time on each word is predicted by the attention weights in transformer-based deep neural networks (DNNs) optimized to perform the same reading task. Eye tracking further reveals that readers separately attend to basic text features and question-relevant information during first-pass reading and rereading, respectively. Similarly, text features and question relevance separately modulate attention weights in shallow and deep DNN layers. Furthermore, when readers scan a passage without a question in mind, their reading time is predicted by DNNs optimized for a word prediction task. Therefore, we offer a computational account of how task optimization modulates attention distribution during real-world reading.


Assuntos
Compreensão , Movimentos Oculares , Humanos , Objetivos , Atenção , Redes Neurais de Computação
3.
Cereb Cortex ; 33(18): 10036-10046, 2023 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-37491998

RESUMO

Speech comprehension is a complex process involving multiple stages, such as decoding of phonetic units, recognizing words, and understanding sentences and passages. In this study, we identify cortical networks beyond basic phonetic processing using a novel passage learning paradigm. Participants learn to comprehend a story composed of syllables of their native language, but containing unfamiliar vocabulary and syntax. Three learning methods are employed, each resulting in some degree of learning within a 12-min learning session. Functional magnetic resonance imaging results reveal that, when listening to the same story, the classic temporal-frontal language network is significantly enhanced by learning. Critically, activation of the left anterior and posterior temporal lobe correlates with the learning outcome that is assessed behaviorally through, e.g. word recognition and passage comprehension tests. This study demonstrates that a brief learning session is sufficient to induce neural plasticity in the left temporal lobe, which underlies the transformation from phonetic units to the units of meaning, such as words and sentences.


Assuntos
Percepção da Fala , Vocabulário , Humanos , Aprendizagem , Idioma , Fala , Fonética , Percepção da Fala/fisiologia , Imageamento por Ressonância Magnética/métodos , Compreensão/fisiologia , Mapeamento Encefálico
4.
eNeuro ; 10(8)2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37500493

RESUMO

When listening to speech, the low-frequency cortical response below 10 Hz can track the speech envelope. Previous studies have demonstrated that the phase lag between speech envelope and cortical response can reflect the mechanism by which the envelope-tracking response is generated. Here, we analyze whether the mechanism to generate the envelope-tracking response is modulated by the level of consciousness, by studying how the stimulus-response phase lag is modulated by the disorder of consciousness (DoC). It is observed that DoC patients in general show less reliable neural tracking of speech. Nevertheless, the stimulus-response phase lag changes linearly with frequency between 3.5 and 8 Hz, for DoC patients who show reliable cortical tracking to speech, regardless of the consciousness state. The mean phase lag is also consistent across these DoC patients. These results suggest that the envelope-tracking response to speech can be generated by an automatic process that is barely modulated by the consciousness state.


Assuntos
Transtornos da Consciência , Percepção da Fala , Humanos , Estado de Consciência , Estimulação Acústica/métodos , Percepção da Fala/fisiologia , Eletroencefalografia/métodos
5.
J Cogn Neurosci ; 35(8): 1361-1368, 2023 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-37262360

RESUMO

When listening to connected speech, the human brain can extract multiple levels of linguistic units, such as syllables, words, and sentences. It has been hypothesized that the time scale of cortical activity encoding each linguistic unit is commensurate with the time scale of that linguistic unit in speech. Evidence for the hypothesis originally comes from studies using the frequency-tagging paradigm that presents each linguistic unit at a constant rate, and more recently extends to studies on natural speech. For natural speech, it is sometimes assumed that neural encoding of different levels of linguistic units is captured by the neural response tracking speech envelope in different frequency bands (e.g., around 1 Hz for phrases, around 2 Hz for words, and around 4 Hz for syllables). Here, we analyze the coherence between speech envelope and idealized responses, each of which tracks a single level of linguistic unit. Four units, that is, phones, syllables, words, and sentences, are separately considered. We show that the idealized phone-, syllable-, and word-tracking responses all correlate with the speech envelope both around 3-6 Hz and below ∼1 Hz. Further analyses reveal that the 1-Hz correlation mainly originates from the pauses in connected speech. The results here suggest that a simple frequency-domain decomposition of envelope-tracking activity cannot separate the neural responses to different linguistic units in natural speech.


Assuntos
Percepção da Fala , Fala , Humanos , Fala/fisiologia , Magnetoencefalografia/métodos , Percepção da Fala/fisiologia , Linguística , Idioma
6.
Neurosci Biobehav Rev ; 147: 105111, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36822385

RESUMO

The syllable is a perceptually salient unit in speech. Since both the syllable and its acoustic correlate, i.e., the speech envelope, have a preferred range of rhythmicity between 4 and 8 Hz, it is hypothesized that theta-band neural oscillations play a major role in extracting syllables based on the envelope. A literature survey, however, reveals inconsistent evidence about the relationship between speech envelope and syllables, and the current study revisits this question by analyzing large speech corpora. It is shown that the center frequency of speech envelope, characterized by the modulation spectrum, reliably correlates with the rate of syllables only when the analysis is pooled over minutes of speech recordings. In contrast, in the time domain, a component of the speech envelope is reliably phase-locked to syllable onsets. Based on a speaker-independent model, the timing of syllable onsets explains about 24% variance of the speech envelope. These results indicate that local features in the speech envelope, instead of the modulation spectrum, are a more reliable acoustic correlate of syllables.


Assuntos
Percepção da Fala , Fala , Humanos , Estimulação Acústica , Acústica , Periodicidade
7.
PLoS One ; 17(4): e0265412, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35381002

RESUMO

Architects should consider the aesthetic experience of potential users when designing architectures. Previous studies have shown that subjective aesthetic judgment of architectures is influenced by structure features, and Western observers prefer structures that have curvilinear contours, high ceilings, and open space. The building styles, however, vary across cultures, and it remains unclear whether the preference for contours, ceiling height, and openness exist across cultures. To investigate this issue, this study analyzes the aesthetic judgment of Chinese observers, and the results demonstrate that Chinese observers also prefer high ceilings and open space. Preference for curvilinear contours, however, interacts with ceiling height and openness. Simple effect analysis reveals that Chinese observers prefer curvilinear contours only when the ceiling is low and the space is closed. In sum, these results suggest that preference for high ceilings and open space is robust for Chinese observers, but the preference for curvilinear contours is less reliable.


Assuntos
Percepção de Forma , Julgamento , China , Estética
8.
eNeuro ; 8(4)2021.
Artigo em Inglês | MEDLINE | ID: mdl-34380659

RESUMO

When listening to speech, low-frequency cortical activity tracks the speech envelope. It remains controversial, however, whether such envelope-tracking neural activity reflects entrainment of neural oscillations or superposition of transient responses evoked by sound features. Recently, it is suggested that the phase of envelope-tracking activity can potentially distinguish entrained oscillations and evoked responses. Here, we analyze the phase of envelope-tracking in humans during passive listening, and observe that the phase lag between cortical activity and speech envelope tends to change linearly across frequency in the θ band (4-8 Hz), suggesting that the θ-band envelope-tracking activity can be readily modeled by evoked responses.


Assuntos
Gastrópodes , Percepção da Fala , Animais , Percepção Auditiva , Eletroencefalografia , Humanos , Som , Fala
9.
Artigo em Inglês | MEDLINE | ID: mdl-34300164

RESUMO

In 2020, the coronavirus pandemic devasted public health agencies and the federal government across the world. Bridging the gap between underserved populations and the healthcare system, the donation-based crowdfunding campaign has opened a new way for suffering individuals and families to access broader social network platforms for financial and non-financial assistance. Despite the growing popularity of crowdfunding during the pandemic crisis, little research has explored the various signals that attract potential donors to donate. This study explores the effects of signaling theory on the success of a crowdfunding campaign for food relief launched in GoFundMe during which the United States was severely affected by the pandemic with a surged number of coronavirus infected cases from 1 March with 134 confirmed COVID-19 infected cases to 29 July with 4,295,308 infected cases according to World Health Organization. The following results show that the three different signal success measures are important to the success of crowdfunding campaigns: (1) signals originating from the campaign (Title, Description, Spelling Error, Location, and Picture); (2) signals originating from the fundraiser (Social Network, and Update); and (3) signals originating from the social interaction of the fundraiser with the crowd (Comment, Follower, and Share). These findings provide insight and bring additional knowledge contribution to the crowdfunding literature.


Assuntos
COVID-19 , Crowdsourcing , Obtenção de Fundos , Atenção à Saúde , Humanos , SARS-CoV-2 , Estados Unidos
10.
Front Neurosci ; 15: 646543, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33994924

RESUMO

Effective diagnosis and prognosis of patients with disorders of consciousness (DOC) provides a basis for family counseling, decision-making, and the design of rehabilitation programs. However, effective and objective bedside evaluation is a challenging problem. In this study, we explored electroencephalography (EEG) response tracking sound rhythms as potential neural markers for DOC evaluation. We analyzed the responses to natural speech and tones modulated at 2 and 41 Hz. At the population level, patients with positive outcomes (DOC-P) showed higher cortical synchronization to modulated tones at 41 Hz compared with patients with negative outcomes (DOC-N). At the individual level, phase coherence to modulated tones at 41 Hz was significantly correlated with Coma Recovery Scale-Revised (CRS-R) and Glasgow Outcome Scale-Extended (GOS-E) scores. Furthermore, SVM classifiers, trained using phase coherences in higher frequency bands or combination of the low frequency aSSR and speech tracking responses, performed very well in diagnosis and prognosis of DOC. These findings show that EEG response to auditory rhythms is a potential tool for diagnosis, severity, and prognosis of DOC.

11.
Sheng Li Xue Bao ; 71(6): 935-945, 2019 Dec 25.
Artigo em Chinês | MEDLINE | ID: mdl-31879748

RESUMO

Speech comprehension is a central cognitive function of the human brain. In cognitive neuroscience, a fundamental question is to understand how neural activity encodes the acoustic properties of a continuous speech stream and resolves multiple levels of linguistic structures at the same time. This paper reviews the recently developed research paradigms that employ electroencephalography (EEG) or magnetoencephalography (MEG) to capture neural tracking of acoustic features or linguistic structures of continuous speech. This review focuses on two questions in speech processing: (1) The encoding of continuously changing acoustic properties of speech; (2) The representation of hierarchical linguistic units, including syllables, words, phrases and sentences. Studies have found that the low-frequency cortical activity tracks the speech envelope. In addition, the cortical activities on different time scales track multiple levels of linguistic units and constitute a representation of hierarchically organized linguistic units. The article reviewed these studies, which provided new insights into the processes of continuous speech in the human brain.


Assuntos
Eletroencefalografia , Magnetoencefalografia , Fala , Estimulação Acústica , Humanos , Fala/fisiologia , Percepção da Fala
12.
Neuroimage ; 192: 66-75, 2019 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-30822469

RESUMO

Recognizing speech in noisy environments is a challenging task that involves both auditory and language mechanisms. Previous studies have demonstrated human auditory cortex can reliably track the temporal envelope of speech in noisy environments, which provides a plausible neural basis for noise-robust speech recognition. The current study aimed at teasing apart auditory and language contributions to noise-robust envelope tracking by comparing the neural responses of 2 groups of listeners, i.e., native listeners and foreign listeners who did not understand the testing language. In the experiment, speech signals were mixed with spectrally matched stationary noise at 4 intensity levels and listeners' neural responses were recorded using electroencephalography (EEG). When the noise intensity increased, the neural response gain increased in both groups of listeners, demonstrating auditory gain control. Language comprehension generally reduced the response gain and envelope-tracking precision, and modulated the spatial and temporal profile of envelope-tracking activity. Based on the spatio-temporal dynamics of envelope-tracking activity, a linear classifier can jointly decode the 2 listener groups and 4 levels of noise intensity. Altogether, the results showed that without feedback from language processing, auditory mechanisms such as gain control can lead to a noise-robust speech representation. High-level language processing modulated the spatio-temporal profile of the neural representation of speech envelope, instead of generally enhancing the envelope representation.


Assuntos
Encéfalo/fisiologia , Idioma , Ruído , Percepção da Fala/fisiologia , Adolescente , Adulto , Compreensão/fisiologia , Feminino , Humanos , Masculino , Adulto Jovem
13.
Cereb Cortex ; 29(4): 1561-1571, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-29788144

RESUMO

Segregating concurrent sound streams is a computationally challenging task that requires integrating bottom-up acoustic cues (e.g. pitch) and top-down prior knowledge about sound streams. In a multi-talker environment, the brain can segregate different speakers in about 100 ms in auditory cortex. Here, we used magnetoencephalographic (MEG) recordings to investigate the temporal and spatial signature of how the brain utilizes prior knowledge to segregate 2 speech streams from the same speaker, which can hardly be separated based on bottom-up acoustic cues. In a primed condition, the participants know the target speech stream in advance while in an unprimed condition no such prior knowledge is available. Neural encoding of each speech stream is characterized by the MEG responses tracking the speech envelope. We demonstrate that an effect in bilateral superior temporal gyrus and superior temporal sulcus is much stronger in the primed condition than in the unprimed condition. Priming effects are observed at about 100 ms latency and last more than 600 ms. Interestingly, prior knowledge about the target stream facilitates speech segregation by mainly suppressing the neural tracking of the non-target speech stream. In sum, prior knowledge leads to reliable speech segregation in auditory cortex, even in the absence of reliable bottom-up speech segregation cue.


Assuntos
Córtex Auditivo/fisiologia , Sinais (Psicologia) , Percepção da Fala/fisiologia , Estimulação Acústica , Adolescente , Adulto , Atenção , Feminino , Humanos , Magnetoencefalografia , Masculino , Acústica da Fala , Adulto Jovem
14.
Nat Commun ; 9(1): 5374, 2018 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-30560906

RESUMO

The sensory and motor systems jointly contribute to complex behaviors, but whether motor systems are involved in high-order perceptual tasks such as speech and auditory comprehension remain debated. Here, we show that ocular muscle activity is synchronized to mentally constructed sentences during speech listening, in the absence of any sentence-related visual or prosodic cue. Ocular tracking of sentences is observed in the vertical electrooculogram (EOG), whether the eyes are open or closed, and in eye blinks measured by eyetracking. Critically, the phase of sentence-tracking ocular activity is strongly modulated by temporal attention, i.e., which word in a sentence is attended. Ocular activity also tracks high-level structures in non-linguistic auditory and visual sequences, and captures rapid fluctuations in temporal attention. Ocular tracking of non-visual rhythms possibly reflects global neural entrainment to task-relevant temporal structures across sensory and motor areas, which could serve to implement temporal attention and coordinate cortical networks.


Assuntos
Estimulação Acústica/psicologia , Córtex Auditivo/fisiologia , Percepção Auditiva/fisiologia , Movimentos Oculares/fisiologia , Fala , Adulto , Atenção/fisiologia , Compreensão/fisiologia , Eletronistagmografia , Eletroculografia , Feminino , Humanos , Masculino , Adulto Jovem
15.
Toxicology ; 285(3): 104-13, 2011 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-21549799

RESUMO

Olaquindox is used in China as feed additive for growth promotion in pigs. Recently, we have demonstrated that olaquindox induced genome DNA damage and oxidative stress in HepG2 cells. The aim of this study was to explore the molecular mechanism of cell cycle arrest and apoptosis induced by olaquindox in HepG2 cells. In the present study olaquindox induced cell cycle arrest to the S phase and dose-dependent apoptotic cell death in HepG2 cells, indicated by accumulation of sub-G1 cell population, nuclear condenstion, DNA fragmentation, caspases activation and PARP cleavage. Meanwhile, the data showed that olaquindox triggered ROS-mediated apoptosis in HepG2 cells correlated with both the mitochondrial DNA damage and nuclear DNA damage, collapse of Δψ(m), opening of mPTP, down-regulation of Bcl-2 and up-regulation of Bax. Furthermore, we also found that olaquindox increased the expression of p53 protein and induced the release of cytochrome C from mitochondria to cytosol. In conclusion, olaquindox induced apoptosis of HepG2 cells through a caspase-9 and -3 dependent mitochondrial pathway, involving p53, Bcl-2 family protein expression, Δψ(m) disruption and mPTP opening.


Assuntos
Apoptose/efeitos dos fármacos , Mitocôndrias Hepáticas/efeitos dos fármacos , Quinoxalinas/farmacologia , Caspase 3/metabolismo , Caspase 9/metabolismo , Caspases/metabolismo , Ciclo Celular/efeitos dos fármacos , Citocromos c/metabolismo , Dano ao DNA/efeitos dos fármacos , Células Hep G2/efeitos dos fármacos , Humanos , Marcação In Situ das Extremidades Cortadas , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Poli(ADP-Ribose) Polimerases/metabolismo , Reação em Cadeia da Polimerase , Proteína Supressora de Tumor p53/metabolismo , Proteína X Associada a bcl-2/metabolismo
16.
Toxicol Lett ; 201(3): 205-12, 2011 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-21195149

RESUMO

Furazolidone (FZD) is an antimicrobial agent that has been shown to have mutagenic, genotoxic and potentially carcinogenic properties when tested in a variety of systems in vitro and in vivo. In this study, we investigated FZD's DNA damaging effect in human hepatoma cells aiming at further defining the molecular mechanism of FZD's cytotoxicity. Addition of FZD resulted in cell growth suppression and cell cycle arrest in S phase accompanied by remarkable DNA strand breaks with increased levels of intracellular reactive oxygen species (ROS) and 8-hydroxydeoxyguanosine. Activities of antioxidases were down-regulated following FZD treatment and antioxidant agent catalase and superoxide dismutase ameliorated FZD's DNA damaging effects. Moreover, FZD caused much more extensive damage to mitochondrial DNA (mtDNA) than to nuclear DNA for which the decrease in mtDNA content correlated with FZD usage in a dose-dependent manner. However, there was no evidence of FZD induced mtDNA mutation in the mitochondrial DNA displacement loop. These results demonstrate that FZD up-regulates the production of intracellular ROS to cause oxidative DNA damage with mtDNA being the most vulnerable targets. Oxidative stress and the injury of mtDNA could be early indicators of FZD-induced cytotoxicity, with the resulting abnormal progression of the cell cycle.


Assuntos
Anti-Infecciosos Locais/toxicidade , Ciclo Celular/efeitos dos fármacos , Dano ao DNA , Furazolidona/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , 8-Hidroxi-2'-Desoxiguanosina , Antioxidantes/metabolismo , Linhagem Celular Tumoral , Núcleo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Ensaio Cometa , DNA Mitocondrial/efeitos dos fármacos , Desoxiguanosina/análogos & derivados , Desoxiguanosina/metabolismo , Humanos , Mutação/efeitos dos fármacos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fase S/efeitos dos fármacos , Regulação para Cima
17.
Toxicol In Vitro ; 23(7): 1209-14, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19665546

RESUMO

Quinocetone, a new quinoxaline 1,4-dioxide derivative, has been approved as an animal growth promoter in China since 2003. To investigate the genotoxicity of quinocetone in vitro, its effects on the extent of DNA injury in human hepatoma (HepG2) cells accompanied by chromosomal damage and genomic DNA alterations were tested. The cell viability test indicated that quinocetone inhibited cell proliferation as a function of dose and time. In the comet assay, significant DNA fragment migration was observed in a dose-dependent manner. A dose-dependent increase of the micronucleated (MN) cell frequency was shown in cytokinesis-block micronucleus (CBMN) test. The gain/loss of randomly amplified polymorphic DNA (RAPD) bands and the change of band intensity in RAPD profiles were obtained after HepG2 cells were exposed to quinocetone at concentrations of 1.25, 2.5 and 5 microg/mL. The results demonstrated that quinocetone exerted genotoxic effects on HepG2 cells. Thus, the use of quinocetone as a growth promoter in animal feed should be seriously considered.


Assuntos
Mutagênicos/toxicidade , Quinoxalinas/toxicidade , Linhagem Celular Tumoral , Divisão do Núcleo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Ensaio Cometa , Citocinese/efeitos dos fármacos , Dano ao DNA , Humanos , Testes para Micronúcleos , Mutagênicos/química , Quinoxalinas/química , Técnica de Amplificação ao Acaso de DNA Polimórfico
18.
Mutat Res ; 676(1-2): 27-33, 2009 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-19486861

RESUMO

Olaquindox, a synthetic antimicrobial compound, is widely used in China as feed additive for growth promotion. However, it is a mutagen with its functional mechanism yet to be unclear. The purpose of this study was to investigate the genotoxic effects of olaquindox in human hepatoma G2 (HepG2) cells and to determine whether the oxidative DNA damage participated in the mechanism of olaquindox toxicity. The results of cell survival assay revealed that the HepG2 cells viabilities were significantly inhibited by olaquindox in a dose- and time-dependent manner. The cytokinesis-block micronucleus (CBMN) assay demonstrated a clear dose-response relationship between olaquindox treatments and micronucleus (MN) frequencies. Moreover, marked increases of DNA fragment migration were observed in the single cell gel electrophoresis (SCGE) assay. These data suggest that olaquindox treatment produced serious chromosome damage and DNA damage in HepG2 cells. To elucidate the possible oxidative DNA damage mechanism of olaquindox genotoxic activity, the levels of the intracellular reactive oxygen species (ROS) and the formation of 8-hydroxydeoxyguanosine (8-OHdG) were detected. The results showed that olaquindox induced the increased levels of ROS and 8-OHdG in HepG2 cells. Considering all the results, it is inferred that olaquindox exerts genotoxic effects in HepG2 cells probably through the ROS-induced oxidative DNA damage.


Assuntos
Carcinoma Hepatocelular/patologia , Quebras de DNA/efeitos dos fármacos , Quinoxalinas/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Carcinoma Hepatocelular/genética , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , China , DNA/efeitos dos fármacos , Relação Dose-Resposta a Droga , Humanos , Neoplasias Hepáticas/patologia , Testes de Mutagenicidade/métodos , Oxirredução , Estresse Oxidativo/efeitos dos fármacos
19.
Food Chem Toxicol ; 47(2): 328-34, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19061932

RESUMO

Quinoxaline-1,4-dioxides derivatives have been widely used as animal growth promoter. This study was conducted to investigate the cytotoxicity and genotoxicity of quinoxaline-1,4-dioxides derivatives, namely carbadox, olaquindox and quinocetone, in Vero cells. The cell viability results from MTT assay demonstrated the severe inhibitory effects by these chemicals in both dose and time dependent manner. Among these chemicals quinocetone exhibited the highest cytotoxicity followed by olaquindox and carbadox. DNA damage analyses using alkalic comet assay revealed pronounced increase of DNA fragmentation in all three compound treated cells. In contrast, DNA damage was significantly decreased after incubation with S9 mix. These findings suggest that the intermediate metabolites of these compounds exerted lower genotoxicity than their parent drugs. We further described chromosomal damage induced by these drugs employing cytokinesis-block micronucleus assay (MN assays). The micronucleus frequency was significantly higher in these drugs treated cells than that of controls and the nuclear division index was also markedly reduced with increasing drug concentration applied. Similar to the observation in comet assay, incorporation of S9 mix in the MN assays was able to markedly alleviate the chromosome damage. In conclusion, our results strengthened previous reports on the cytotoxicity and genotoxicity of carbadox, olaquindox and quinocetone.


Assuntos
Carbadox/toxicidade , Chlorocebus aethiops , Mutagênicos/toxicidade , Quinoxalinas/toxicidade , Animais , Sobrevivência Celular/efeitos dos fármacos , Ensaio Cometa , DNA/efeitos dos fármacos , Dano ao DNA , Relação Dose-Resposta a Droga , Formazans/metabolismo , Micronúcleos com Defeito Cromossômico/induzido quimicamente , Testes para Micronúcleos , Microssomos Hepáticos , Mitose/efeitos dos fármacos , Sais de Tetrazólio/metabolismo , Células Vero
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...