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1.
Metallomics ; 14(6)2022 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-35482657

RESUMO

Gadolinium (Gd) deposition has been found in both animal and human tissues after injections of Gd-based contrast agents (GBCAs). Without the knowledge of which tissues are most affected, it is difficult to determine whether Gd accumulation could lead to any pathological changes. The current study aims at investigating histological sections of three patients who were exposed to GBCAs during their lifetime, and identify areas of Gd accumulation. Tissue sections of three autopsy cases were investigated by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to assess the distribution of Gd, and the deposition within tissue sections was quantified. Additional application of laser ablation-inductively coupled plasma-optical emission spectroscopy (LA-ICP-OES) enabled a sensitive detection of calcium (Ca) in the vessel walls, which is usually impeded in LA-ICP-MS due to the isobaric interference with argon. Complementary LA-ICP-MS and LA-ICP-OES analysis revealed that Gd was co-localized with zinc and Ca, in the area where smooth muscle actin was present. Notably, high levels of Gd were found in the tunica media of arterial walls, which requires further research into potential Gd-related toxicity in this specific location.


Assuntos
Meios de Contraste , Gadolínio , Animais , Meios de Contraste/química , Humanos , Imageamento por Ressonância Magnética/métodos , Coloração e Rotulagem , Túnica Média/química
2.
JPEN J Parenter Enteral Nutr ; 44(2): 337-347, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-30861163

RESUMO

BACKGROUND: The toxic effect of chemotherapy on the gastrointestinal tract may lead to mucositis and is associated with the pathogenesis of other treatment-related complications. We hypothesized that nutrition supplementation with bovine colostrum, rich in bioactive factors, would ameliorate gastrointestinal toxicity and reduce the incidence of fever and infectious complications during induction treatment for childhood acute lymphoblastic leukemia (ALL). METHODS: Children with newly diagnosed ALL were included in a 2-center, randomized, double-blind, placebo-controlled clinical trial. Patients were randomized to receive a daily colostrum or placebo supplement during 4 weeks of induction treatment. Data on fever, bacteremia, need for antibiotics, and mucosal toxicity were prospectively collected. (Trial registration: www.clinicaltrials.gov NCT01766804). RESULTS: Sixty-two patients were included. No differences were found for the primary outcome (number of days with fever). No difference was observed for neutropenic fever, intravenous antibiotics, or incidence of bacteremia. Peak severity of oral mucositis was significantly reduced by colostrum (7/29 patients, 24% mild; 6/29, 21% moderate; 1/29, 3% severe) compared with placebo (12/31, 39% mild; 1/31, 3% moderate; 7/31, 23% severe) (P = 0.02). Among patients receiving at least 1 dose of supplement (colostrum: n = 22; placebo: n = 30), the peak weekly self-reported oral mucositis score was overall significantly less severe in the colostrum group (P = 0.009). CONCLUSION: The use of prophylactic bovine colostrum showed no effect on fever, infectious morbidity, or inflammatory responses. Nevertheless, these data may suggest protective effects on the oral mucosa during induction therapy in childhood ALL, encouraging additional studies confirming these findings.


Assuntos
Antineoplásicos , Colostro , Gastroenteropatias , Leucemia-Linfoma Linfoblástico de Células Precursoras , Animais , Antineoplásicos/efeitos adversos , Bovinos , Criança , Método Duplo-Cego , Feminino , Gastroenteropatias/induzido quimicamente , Gastroenteropatias/tratamento farmacológico , Humanos , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Gravidez
3.
PLoS One ; 14(1): e0207351, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30682025

RESUMO

Brain-Computer Interfaces (BCIs) are inefficient for a non-negligible part of the population, estimated around 25%. To understand this phenomenon in Sensorimotor Rhythm (SMR) based BCIs, data from a large-scale screening study conducted on 80 novice participants with the Berlin BCI system and its standard machine-learning approach were investigated. Each participant performed one BCI session with resting state Encephalography, Motor Observation, Motor Execution and Motor Imagery recordings and 128 electrodes. A significant portion of the participants (40%) could not achieve BCI control (feedback performance > 70%). Based on the performance of the calibration and feedback runs, BCI users were stratified in three groups. Analyses directed to detect and elucidate the differences in the SMR activity of these groups were performed. Statistics on reactive frequencies, task prevalence and classification results are reported. Based on their SMR activity, also a systematic list of potential reasons leading to performance drops and thus hints for possible improvements of BCI experimental design are given. The categorization of BCI users has several advantages, allowing researchers 1) to select subjects for further analyses as well as for testing new BCI paradigms or algorithms, 2) to adopt a better subject-dependent training strategy and 3) easier comparisons between different studies.


Assuntos
Interfaces Cérebro-Computador , Córtex Sensório-Motor/fisiologia , Adolescente , Adulto , Idoso , Biorretroalimentação Psicológica , Calibragem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
4.
IEEE Trans Neural Syst Rehabil Eng ; 25(10): 1735-1745, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-27849545

RESUMO

We provide an open access dataset for hybrid brain-computer interfaces (BCIs) using electroencephalography (EEG) and near-infrared spectroscopy (NIRS). For this, we con-ducted two BCI experiments (left vs. right hand motor imagery; mental arithmetic vs. resting state). The dataset was validated using baseline signal analysis methods, with which classification performance was evaluated for each modality and a combination of both modalities. As already shown in previous literature, the capability of discriminating different mental states can be en-hanced by using a hybrid approach, when comparing to single modality analyses. This makes the provided data highly suitable for hybrid BCI investigations. Since our open access dataset also comprises motion artifacts and physiological data, we expect that it can be used in a wide range of future validation approaches in multimodal BCI research.

5.
Brain Behav ; 6(10): e00548, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27781151

RESUMO

INTRODUCTION: Radiation therapy plays an essential role in the treatment of brain tumors, but neurocognitive deficits remain a significant risk, especially in pediatric patients. In recent trials, hippocampal sparing techniques are applied to reduce these adverse effects. Here, we investigate dose-dependent effects of ionizing radiation (IR) on juvenile hippocampal neurogenesis. Additionally, we evaluate the radioprotective potential of resveratrol, a plant polyphenol recognized for its bifunctional tumor-preventive and anticancer effects. METHODS: Organotypic entorhinal-hippocampal slice cultures from transgenic nestin-CFPnuc C57BL/J6 mice, postnatal days 3-6, were irradiated on a X-ray machine (4.5, 8, 12, and 16 Gy, single doses) after about 2 weeks. Nestin-positive neural stem cells were counted at a confocal live imaging microscope 0, 2, 4, 14, 25, and 42 days after IR. Resveratrol (15 µmol/L) was added 2 hr before and 24 hr after IR. Proliferation and cell death were assessed by BrdU pulse label, 48 hr after and by propidium iodide staining 96 hr after IR. GFAP- and NeuN-positive cells were counted 42 days after IR in cryosectioned immunofluorescence-stained slices. RESULTS: The observed age-related changes of nestin-positive stem cells in the organotypic slice culture model resembled the reduction of neural stem cells in vivo. IR (4.5-16 Gy) led to a dose-dependent damage of the neural stem cell pool in the dentate gyrus. No recovery was seen within 42 days after doses from 4.5 Gy onward. The decline of nestin-positive cells was paralleled by increased cell death and decreased proliferation. The number of GFAP-positive cells was significantly enhanced. No significant change was detected in the overall NeuN-positive cell population, whereas the number of newborn, NeuN/BrdU double-positive neurons was reduced. Resveratrol treatment reversed the irradiation-induced decline of neural stem cells. CONCLUSION: The neuroprotective action of resveratrol on irradiated hippocampal tissue warrants further investigation as a possible supplement to hippocampal sparing procedures.


Assuntos
Hipocampo/efeitos dos fármacos , Células-Tronco Neurais/efeitos dos fármacos , Células-Tronco Neurais/efeitos da radiação , Fármacos Neuroprotetores/farmacologia , Lesões Experimentais por Radiação/tratamento farmacológico , Protetores contra Radiação/farmacologia , Estilbenos/farmacologia , Animais , Morte Celular/efeitos dos fármacos , Morte Celular/efeitos da radiação , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/efeitos da radiação , Relação Dose-Resposta à Radiação , Avaliação Pré-Clínica de Medicamentos , Hipocampo/patologia , Hipocampo/fisiopatologia , Hipocampo/efeitos da radiação , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microscopia Confocal , Nestina/genética , Nestina/metabolismo , Células-Tronco Neurais/patologia , Células-Tronco Neurais/fisiologia , Neuroglia/efeitos dos fármacos , Neuroglia/patologia , Neuroglia/fisiologia , Neuroglia/efeitos da radiação , Neurônios/efeitos dos fármacos , Neurônios/patologia , Neurônios/fisiologia , Neurônios/efeitos da radiação , Lesões Experimentais por Radiação/patologia , Lesões Experimentais por Radiação/fisiopatologia , Radiação Ionizante , Resveratrol , Fatores de Tempo , Técnicas de Cultura de Tecidos , Raios X
6.
Am J Physiol Gastrointest Liver Physiol ; 311(2): G324-33, 2016 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-27445347

RESUMO

Chemotherapy-induced gastrointestinal (GI) toxicity is a common adverse effect of cancer treatment. We used preweaned piglets as models to test our hypothesis that the immunomodulatory and GI trophic effects of bovine colostrum would reduce the severity of GI complications associated with doxorubicin (DOX) treatment. Five-day-old pigs were administered DOX (1 × 100 mg/m(2)) or an equivalent volume of saline (SAL) and either fed formula (DOX-Form, n = 9, or SAL-Form, n = 7) or bovine colostrum (DOX-Colos, n = 9, or SAL-Colos, n = 7). Pigs were euthanized 5 days after initiation of chemotherapy to assess markers of small intestinal function and inflammation. All DOX-treated animals developed diarrhea, growth deficits, and leukopenia. However, the intestines of DOX-Colos pigs had lower intestinal permeability, longer intestinal villi with higher activities of brush border enzymes, and lower tissue IL-8 levels compared with DOX-Form (all P < 0.05). DOX-Form pigs, but not DOX-Colos pigs, had significantly higher plasma C-reactive protein, compared with SAL-Form. Plasma citrulline was not affected by DOX treatment or diet. Thus a single dose of DOX induces intestinal toxicity in preweaned pigs and may lead to a systemic inflammatory response. The toxicity is affected by type of enteral nutrition with more pronounced GI toxicity when formula is fed compared with bovine colostrum. The results indicate that bovine colostrum may be a beneficial supplementary diet for children subjected to chemotherapy and subsequent intestinal toxicity.


Assuntos
Antibióticos Antineoplásicos , Colostro/metabolismo , Doxorrubicina , Nutrição Enteral/efeitos adversos , Fórmulas Infantis/toxicidade , Mucosa Intestinal/metabolismo , Intestino Delgado/metabolismo , Mucosite/induzido quimicamente , Animais , Animais Recém-Nascidos , Proteína C-Reativa/metabolismo , Bovinos , Modelos Animais de Doenças , Nutrição Enteral/métodos , Feminino , Humanos , Recém-Nascido , Mediadores da Inflamação/sangue , Interleucina-8/metabolismo , Mucosa Intestinal/patologia , Intestino Delgado/patologia , Masculino , Microvilosidades/enzimologia , Microvilosidades/patologia , Mucosite/metabolismo , Mucosite/patologia , Mucosite/fisiopatologia , Estado Nutricional , Permeabilidade , Sus scrofa , Aumento de Peso
7.
J Pediatr Gastroenterol Nutr ; 63(6): 698-707, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27027906

RESUMO

OBJECTIVE: Chemotherapy-induced intestinal toxicity is a common adverse effect of cancer treatment. We hypothesized that a milk diet containing bovine colostrum (BC) would reduce intestinal toxicity in doxorubicin-treated piglets. METHODS: "Study 1" investigated intestinal parameters 9 days after a single dose of doxorubicin (1 × 75 mg/m) in piglets fed bovine milk enriched with whey protein (BM). In "study 2," responses to doxorubicin treatment were investigated in piglets receiving either 7 BC feedings per day (Only-BC, n = 13), 4 BC feedings (High-BC, n = 13), 2 BC feedings (Low-BC, n = 14), or no BC (only BM, n = 13). RESULTS: Doxorubicin treatment induced clinical signs of intestinal toxicity with diarrhea and weight loss, relative to controls (P < 0.05). White blood cells, hexose absorptive function, plasma citrulline, weights of intestine, colon, and spleen were reduced, whereas gut permeability and plasma C-reactive protein levels were increased (all P < 0.05). Limited or no effects were observed for digestive enzymes, proinflammatory cytokines, or tight-junction proteins in the intestine. Increasing BC supplementation to doxorubicin-treated piglets (study 2) had no consistent effects on plasma C-reactive protein and citrulline levels, intestinal morphology, digestive enzymes, permeability, or proinflammatory cytokines. Only-BC pigs, however, had lower diarrhea severity toward the end of the experiment (P < 0.05 vs BM) and across the BC groups, intestinal toxicity was reduced (P < 0.01). CONCLUSIONS: Doxorubicin-treated piglets are relevant for studying chemotherapy-induced gut toxicity. Colostrum supplementation had limited effects on doxorubicin-induced toxicity in milk-fed piglets suggesting that colostrum and a bovine milk diet enriched with whey protein provided similar protection of the developing intestine from chemotherapy-induced toxicity.


Assuntos
Antibióticos Antineoplásicos/toxicidade , Colostro/efeitos dos fármacos , Doxorrubicina/toxicidade , Mucosa Intestinal/efeitos dos fármacos , Animais , Antibióticos Antineoplásicos/administração & dosagem , Proteína C-Reativa , Bovinos , Colostro/metabolismo , Doxorrubicina/administração & dosagem , Feminino , Mucosa Intestinal/metabolismo , Leite/metabolismo , Suínos , Aumento de Peso
8.
J Nutr ; 145(7): 1472-80, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26019247

RESUMO

BACKGROUND: Intensive chemotherapy frequently results in gut toxicity, indicated by oral and intestinal mucositis, resulting in poor treatment outcomes and increased mortality. There are no effective preventive strategies against gut toxicity and the role of diet is unknown. OBJECTIVE: We hypothesized that the severity of chemotherapy-induced gut toxicity in early life is diet-dependent, and that intake of bovine colostrum (BC) provides better gut protection than an artificial milk replacer (MR). METHODS: A total of 37 3-d-old pigs received for 6 d either intravenous saline control or myeloablative treatment with busulfan and cyclophosphamide, and were fed either BC or MR, resulting in the following 4 treatments (n = 8-10/group): bovine colostrum plus saline control (Ctr-BC), milk replacer plus saline control (Ctr-MR), bovine colostrum plus busulfan and cyclophosphamide chemotherapy (BUCY-BC), and milk replacer plus busulfan and cyclophosphamide chemotherapy (BUCY-MR). The gut was collected for analysis 11 d after the start of chemotherapy. RESULTS: Relative to the control groups, both busulfan and cyclophosphamide chemotherapy (BUCY) groups showed signs of gut toxicity, with oral ulcers, reduced intestinal dimensions, and hematologic toxicity. Diet type did not affect mucosal structure on day 11, but BUCY-BC pigs had less vomiting than BUCY-MR pigs (1 of 10 vs. 10 of 10, P < 0.05). Markers of intestinal function were higher (up to 20-fold greater galactose absorption and 2-3-fold greater brush border enzyme activity, all P < 0.05), and tissue inflammatory cytokine concentrations and serum liver enzyme values were lower in BUCY-BC than in BUCY-MR pigs (30-50% reductions in interleukin 6 and 8, aminotransferase, and bilirubin concentrations, P < 0.05). Gut colonization was not significantly affected except that BUCY pigs had lower microbial diversity with a higher abundance of Lactobacilli. CONCLUSION: BC may reduce gut toxicity during myeloablative chemotherapy in piglets by preserving intestinal function and reducing inflammation. Whether similar effects occur in children remains to be tested.


Assuntos
Colostro/química , Intestinos/efeitos dos fármacos , Agonistas Mieloablativos/administração & dosagem , Agonistas Mieloablativos/efeitos adversos , Animais , Animais Recém-Nascidos , Bilirrubina/metabolismo , Bussulfano/administração & dosagem , Bussulfano/efeitos adversos , Bovinos , Citrulina/sangue , Ciclofosfamida/administração & dosagem , Ciclofosfamida/efeitos adversos , Dieta/veterinária , Determinação de Ponto Final , Interleucina-6/metabolismo , Interleucina-8/metabolismo , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/patologia , Intestinos/microbiologia , Intestinos/fisiopatologia , Microbiota , Suínos , Transaminases/metabolismo
9.
PLoS One ; 9(8): e104854, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25162231

RESUMO

Brain-Computer Interfaces (BCIs) strive to decode brain signals into control commands for severely handicapped people with no means of muscular control. These potential users of noninvasive BCIs display a large range of physical and mental conditions. Prior studies have shown the general applicability of BCI with patients, with the conflict of either using many training sessions or studying only moderately restricted patients. We present a BCI system designed to establish external control for severely motor-impaired patients within a very short time. Within only six experimental sessions, three out of four patients were able to gain significant control over the BCI, which was based on motor imagery or attempted execution. For the most affected patient, we found evidence that the BCI could outperform the best assistive technology (AT) of the patient in terms of control accuracy, reaction time and information transfer rate. We credit this success to the applied user-centered design approach and to a highly flexible technical setup. State-of-the art machine learning methods allowed the exploitation and combination of multiple relevant features contained in the EEG, which rapidly enabled the patients to gain substantial BCI control. Thus, we could show the feasibility of a flexible and tailorable BCI application in severely disabled users. This can be considered a significant success for two reasons: Firstly, the results were obtained within a short period of time, matching the tight clinical requirements. Secondly, the participating patients showed, compared to most other studies, very severe communication deficits. They were dependent on everyday use of AT and two patients were in a locked-in state. For the most affected patient a reliable communication was rarely possible with existing AT.


Assuntos
Inteligência Artificial , Interfaces Cérebro-Computador , Encéfalo/fisiologia , Pessoas com Deficiência , Imaginação , Tecnologia Assistiva , Eletroencefalografia , Humanos , Pessoa de Meia-Idade , Tempo de Reação , Fatores de Tempo
10.
J Ethnopharmacol ; 155(1): 165-70, 2014 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-24862489

RESUMO

UNLABELLED: ETNOPHARMACOLOGICAL RELEVANCE: The popularity of concentrated green tea extracts as dietary supplements for a wide range of applications is increasing due to their health-promoting effects attributed to the high amounts of catechins they contain. The most important of the green tea catechins is (-)-epigallocatechin-3-O-gallate (EGCG). While their beneficiary effects have been studied extensively, a small number of adverse events have been reported in the medical literature. Here we present a typical reversible course of severe hepatitis after green tea consumption. MATERIALS AND METHODS: The case study describes in a 63-year old woman during treatment with green tea-capsules upon recommendation of a cancer support group. RESULTS: The histological finding was consistent with drug induced hepatitis, and other possible causes of hepatitis were excluded. According to the CIOMS/RUCAM score the causality was assessed as "probable". After discontinuation of medication, followed by extracorporal albumin dialysis, rapid and sustained recovery occurred. Pharmaceutically analysis (HPLC) of the green tea capsules did not give evidence for contaminants but revealed the two typical compounds of green tea, namely (-)-epigallocatechin-3-O-gallate (EGCG, 93.2%) and epicatechin (EC, 6.8%) at a very high dose level. CONCLUSION: The present case highlights the fact that such concentrated herbal extracts from green tea may not be free of adverse effects under certain circumstances. There is still a lack of a uniform European Union-wide surveillance system for adverse drug reactions of herbal products. Therefore this case underlines the importance of public awareness in the potential risks in use of herbal products.


Assuntos
Doença Hepática Induzida por Substâncias e Drogas/etiologia , Suplementos Nutricionais/efeitos adversos , Extratos Vegetais/efeitos adversos , Chá , Doença Aguda , Camellia sinensis/química , Catequina/análogos & derivados , Catequina/isolamento & purificação , Doença Hepática Induzida por Substâncias e Drogas/fisiopatologia , Cromatografia Líquida de Alta Pressão , Feminino , Humanos , Pessoa de Meia-Idade , Extratos Vegetais/química , Índice de Gravidade de Doença
11.
Nutr Rev ; 72(4): 237-54, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24571383

RESUMO

Bovine colostrum, the first milk that cows produce after parturition, contains high levels of growth factors and immunomodulatory components. Some healthy and diseased individuals may gain health benefits by consuming bovine colostrum as a food supplement. This review provides a systematic, critical evaluation of the current state of knowledge in this area. Fifty-one eligible studies were identified from the following databases: Medline, Embase, Global Health, the Cochrane Library, and the Cumulative Index to Nursing and Allied Health Literature. Studies were heterogeneous with regard to populations, outcomes, and methodological quality, as judged by the Jadad assessment tool. Many studies used surrogate markers to study the effects of bovine colostrum. Studies suggesting clinical benefits of colostrum supplementation were generally of poor methodological quality, and results could not be confirmed by other investigators. Bovine colostrum may provide gastrointestinal and immunological benefits, but further studies are required before recommendations can be made for clinical application. Animal models may help researchers to better understand the mechanisms of bovine colostrum supplementation, the dosage regimens required to obtain clinical benefits, and the optimal methods for testing these effects in humans.


Assuntos
Colostro/química , Suplementos Nutricionais , Fatores Imunológicos/uso terapêutico , Peptídeos e Proteínas de Sinalização Intercelular/uso terapêutico , Animais , Bovinos , Colostro/fisiologia , Humanos , Fatores Imunológicos/análise , Peptídeos e Proteínas de Sinalização Intercelular/análise
12.
PLoS One ; 9(2): e87056, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24551050

RESUMO

Recently, spatio-temporal filtering to enhance decoding for Brain-Computer-Interfacing (BCI) has become increasingly popular. In this work, we discuss a novel, fully Bayesian-and thereby probabilistic-framework, called Bayesian Spatio-Spectral Filter Optimization (BSSFO) and apply it to a large data set of 80 non-invasive EEG-based BCI experiments. Across the full frequency range, the BSSFO framework allows to analyze which spatio-spectral parameters are common and which ones differ across the subject population. As expected, large variability of brain rhythms is observed between subjects. We have clustered subjects according to similarities in their corresponding spectral characteristics from the BSSFO model, which is found to reflect their BCI performances well. In BCI, a considerable percentage of subjects is unable to use a BCI for communication, due to their missing ability to modulate their brain rhythms-a phenomenon sometimes denoted as BCI-illiteracy or inability. Predicting individual subjects' performance preceding the actual, time-consuming BCI-experiment enhances the usage of BCIs, e.g., by detecting users with BCI inability. This work additionally contributes by using the novel BSSFO method to predict the BCI-performance using only 2 minutes and 3 channels of resting-state EEG data recorded before the actual BCI-experiment. Specifically, by grouping the individual frequency characteristics we have nicely classified them into the subject 'prototypes' (like µ - or ß -rhythm type subjects) or users without ability to communicate with a BCI, and then by further building a linear regression model based on the grouping we could predict subjects' performance with the maximum correlation coefficient of 0.581 with the performance later seen in the actual BCI session.


Assuntos
Algoritmos , Interfaces Cérebro-Computador , Probabilidade , Área Sob a Curva , Teorema de Bayes , Análise por Conglomerados , Eletrodos , Eletroencefalografia , Humanos , Imagens, Psicoterapia , Atividade Motora , Análise de Componente Principal , Descanso/fisiologia
13.
J Neural Eng ; 10(5): 056003, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23902853

RESUMO

OBJECTIVE: Assessing speech quality perception is a challenge typically addressed in behavioral and opinion-seeking experiments. Only recently, neuroimaging methods were introduced, which were used to study the neural processing of quality at group level. However, our electroencephalography (EEG) studies show that the neural correlates of quality perception are highly individual. Therefore, it became necessary to establish dedicated machine learning methods for decoding subject-specific effects. APPROACH: The effectiveness of our methods is shown by the data of an EEG study that investigates how the quality of spoken vowels is processed neurally. Participants were asked to indicate whether they had perceived a degradation of quality (signal-correlated noise) in vowels, presented in an oddball paradigm. MAIN RESULTS: We find that the P3 amplitude is attenuated with increasing noise. Single-trial analysis allows one to show that this is partly due to an increasing jitter of the P3 component. A novel classification approach helps to detect trials with presumably non-conscious processing at the threshold of perception. We show that this approach uncovers a non-trivial confounder between neural hits and neural misses. SIGNIFICANCE: The combined use of EEG signals and machine learning methods results in a significant 'neural' gain in sensitivity (in processing quality loss) when compared to standard behavioral evaluation; averaged over 11 subjects, this amounts to a relative improvement in sensitivity of 35%.


Assuntos
Eletroencefalografia/métodos , Percepção da Fala/fisiologia , Estimulação Acústica , Algoritmos , Ritmo alfa/fisiologia , Área Sob a Curva , Inteligência Artificial , Limiar Auditivo , Cognição/fisiologia , Interpretação Estatística de Dados , Análise Discriminante , Eletroculografia , Potenciais Evocados/fisiologia , Feminino , Audição/fisiologia , Humanos , Masculino , Modelos Neurológicos , Desempenho Psicomotor/fisiologia , Indicadores de Qualidade em Assistência à Saúde , Testes de Discriminação da Fala , Tecnologia/normas
14.
Artigo em Inglês | MEDLINE | ID: mdl-23366988

RESUMO

Brain-Computer Interfaces (BCI) based on the voluntary modulation of sensorimotor rhythms (SMRs) induced by motor imagery are very prominent because allow a continuous control of the external device. Nevertheless, the design of a SMR-based BCI system that provides every user with a reliable BCI control from the first session, i.e., without extensive training, is still a big challenge. Considerable advances in this direction have been made by the machine learning co-adaptive calibration approach, which combines online adaptation techniques with subject learning in order to offer the user a feedback from the beginning of the experiment. Recently, based on offline analyses, we proposed the novel Common Spatial Patterns Patches (CSPP) technique as a good candidate to improve the co-adaptive calibration. CSPP is an ensemble of localized spatial filters, each of them optimized on subject-specific data by CSP analysis. Here, the evaluation of CSPP in online operation is presented for the first time. Results on three BCI-naive participants show indeed promising results. All three users reach the threshold criterion of 70% accuracy within one session, even one candidate for whom the weak SMR at rest predicted deficient BCI control. Concurrent recordings of the SMR during a relax condition as well as the course of BCI performance indicate a clear learning effect.


Assuntos
Biorretroalimentação Psicológica/fisiologia , Interfaces Cérebro-Computador , Eletroencefalografia/métodos , Imaginação/fisiologia , Córtex Motor/fisiologia , Movimento/fisiologia , Desempenho Psicomotor/fisiologia , Algoritmos , Biorretroalimentação Psicológica/métodos , Humanos
15.
Biol Psychol ; 89(1): 80-6, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21964375

RESUMO

BACKGROUND: After about 30 years of research on Brain-Computer Interfaces (BCIs) there is little knowledge about the phenomenon, that some people - healthy as well as individuals with disease - are not able to learn BCI-control. To elucidate this "BCI-inefficiency" phenomenon, the current study investigated whether psychological parameters, such as attention span, personality or motivation, could predict performance in a single session with a BCI controlled by modulation of sensorimotor rhythms (SMR) with motor imagery. METHODS: A total of N=83 healthy BCI novices took part in the session. Psychological parameters were measured with an electronic test-battery including clinical, personality and performance tests. Predictors were determined by binary logistic regression analyses. RESULTS: The output variable of the Two-Hand Coordination Test (2HAND) "overall mean error duration" which is a measure for the accuracy of fine motor skills accounted for 11% of the variance in BCI-inefficiency. The Attitudes Towards Work (AHA) test variable "performance level" which can be interpreted as a degree of concentration and a neurophysiological SMR predictor were also identified as significant predictors of SMR BCI performance. CONCLUSION: Psychological parameters as measured in this study play a moderate role for one-session performance in a BCI controlled by modulation of SMR.


Assuntos
Biorretroalimentação Psicológica , Sistemas Homem-Máquina , Movimento/fisiologia , Córtex Somatossensorial/fisiologia , Interface Usuário-Computador , Adolescente , Adulto , Idoso , Algoritmos , Análise de Variância , Cognição/fisiologia , Depressão Alastrante da Atividade Elétrica Cortical/fisiologia , Eletroencefalografia , Feminino , Mãos/inervação , Humanos , Imagens, Psicoterapia , Masculino , Pessoa de Meia-Idade , Inventário de Personalidade , Valor Preditivo dos Testes , Testes Psicológicos , Desempenho Psicomotor/fisiologia , Análise de Regressão , Estatísticas não Paramétricas , Inquéritos e Questionários , Adulto Jovem
16.
Artigo em Inglês | MEDLINE | ID: mdl-23366624

RESUMO

In this study we show how healthy subjects are able to use a non-invasive Motor Imagery (MI)-based Brain Computer Interface (BCI) to achieve linear control of an upper-limb neuromuscular electrical stimulation (NMES) controlled neuroprosthesis in a simple binary target selection task. Linear BCI control can be achieved if two motor imagery classes can be discriminated with a reliability over 80% in single trial. The results presented in this work show that there was no significant loss of performance using the neuroprosthesis in comparison to MI where no stimulation was present. However, it is remarkable how different the experience of the users was in the same experiment. The stimulation either provoked a positive reinforcement feedback, or prevented the user from concentrating in the task.


Assuntos
Braço/fisiologia , Interfaces Cérebro-Computador , Eletroencefalografia/instrumentação , Próteses e Implantes , Biorretroalimentação Psicológica , Estimulação Elétrica , Humanos
17.
Arch Environ Occup Health ; 66(1): 34-42, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21337184

RESUMO

This study investigates the association between lymph node-only and lung silicosis in uranium miners with lung cancer and exposure to quartz dust. Tissue slides of 4,384 German uranium miners with lung cancer were retrieved from an autopsy archive and reviewed by 3 pathologists regarding silicosis in the lungs and lymph nodes. Cumulative exposure to quartz dust was assessed with a quantitative job-exposure matrix. The occurrence of silicosis by site was investigated with regression models for exposure to quartz dust. Miners with lung silicosis had highest cumulative quartz exposure, followed by lymph node-only silicosis and no silicosis. At a cumulative quartz exposure of 40 mg/m(3) × years, the probability of lung silicosis was above 90% and the likelihood of lymph node-only silicosis and no silicosis do not differ anymore. The results support that lymph node silicosis can precede lung silicosis, at least in a proportion of subjects developing silicosis, and that lung silicosis strongly depends on the cumulative quartz dose.


Assuntos
Neoplasias Pulmonares/complicações , Doenças Linfáticas/complicações , Mineração/estatística & dados numéricos , Silicose/complicações , Urânio , Idoso , Poeira , Alemanha/epidemiologia , Humanos , Neoplasias Pulmonares/patologia , Doenças Linfáticas/patologia , Masculino , Pessoa de Meia-Idade , Exposição Ocupacional/efeitos adversos , Exposição Ocupacional/estatística & dados numéricos , Quartzo/toxicidade , Silicose/patologia , Fatores de Tempo
18.
Langmuir ; 27(7): 3534-40, 2011 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-21348504

RESUMO

ZrO(2) powder (6.6 m(2)/g) was modified using polymerizable phosphorus-based coupling agents (P-CAs) (i.e., phosphonic acid, phosphoric acid, and bis-phosphonic acid), resulting in densely grafted layers as determined by thermogravimetry and elemental analysis (up to 4.2 molecules/nm(2)). The applied P-CAs contained a methacrylate group, which led to the covalent incorporation of a polymerizable moiety into the grafted layer. To direct the ordering of the alkyl chains in the layer, three different approaches were evaluated with respect to their structure-directing ability by means of FT-IR and nitrogen sorption at 77 K: (i) variation of the chain length, (ii) variation of the anchoring group and (iii) comodification with a defined amount of a nonfunctional phosphonic acid (variation of the functional/nonfunctional acid ratio). It was shown that the chain length and anchoring group size have significant effects on the alkyl chain ordering and morphology of the layer.


Assuntos
Fósforo/química , Zircônio/química , Difosfonatos/química , Organofosfonatos/química , Ácidos Fosfóricos/química
19.
Neural Comput ; 23(3): 791-816, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21162666

RESUMO

Brain-computer interfaces (BCIs) allow users to control a computer application by brain activity as acquired (e.g., by EEG). In our classic machine learning approach to BCIs, the participants undertake a calibration measurement without feedback to acquire data to train the BCI system. After the training, the user can control a BCI and improve the operation through some type of feedback. However, not all BCI users are able to perform sufficiently well during feedback operation. In fact, a nonnegligible portion of participants (estimated 15%-30%) cannot control the system (a BCI illiteracy problem, generic to all motor-imagery-based BCIs). We hypothesize that one main difficulty for a BCI user is the transition from offline calibration to online feedback. In this work, we investigate adaptive machine learning methods to eliminate offline calibration and analyze the performance of 11 volunteers in a BCI based on the modulation of sensorimotor rhythms. We present an adaptation scheme that individually guides the user. It starts with a subject-independent classifier that evolves to a subject-optimized state-of-the-art classifier within one session while the user interacts continuously. These initial runs use supervised techniques for robust coadaptive learning of user and machine. Subsequent runs use unsupervised adaptation to track the features' drift during the session and provide an unbiased measure of BCI performance. Using this approach, without any offline calibration, six users, including one novice, obtained good performance after 3 to 6 minutes of adaptation. More important, this novel guided learning also allows participants with BCI illiteracy to gain significant control with the BCI in less than 60 minutes. In addition, one volunteer without sensorimotor idle rhythm peak at the beginning of the BCI experiment developed it during the course of the session and used voluntary modulation of its amplitude to control the feedback application.


Assuntos
Inteligência Artificial , Interfaces Cérebro-Computador , Calibragem , Adaptação Fisiológica , Adaptação Psicológica , Algoritmos , Encéfalo/fisiologia , Eletroencefalografia/métodos , Retroalimentação Psicológica , Humanos , Plasticidade Neuronal
20.
J Chem Inf Model ; 51(1): 83-92, 2011 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-21166393

RESUMO

Screening large libraries of chemical compounds against a biological target, typically a receptor or an enzyme, is a crucial step in the process of drug discovery. Virtual screening (VS) can be seen as a ranking problem which prefers as many actives as possible at the top of the ranking. As a standard, current Quantitative Structure-Activity Relationship (QSAR) models apply regression methods to predict the level of activity for each molecule and then sort them to establish the ranking. In this paper, we propose a top-k ranking algorithm (StructRank) based on Support Vector Machines to solve the early recognition problem directly. Empirically, we show that our ranking approach outperforms not only regression methods but another ranking approach recently proposed for QSAR ranking, RankSVM, in terms of actives found.


Assuntos
Avaliação Pré-Clínica de Medicamentos/métodos , Interface Usuário-Computador , Inteligência Artificial , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Ligantes , Análise de Regressão , Relação Estrutura-Atividade , Fatores de Tempo
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