Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 114
Filtrar
1.
PLoS Comput Biol ; 20(7): e1012257, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38959262

RESUMO

Neuromechanical studies investigate how the nervous system interacts with the musculoskeletal (MSK) system to generate volitional movements. Such studies have been supported by simulation models that provide insights into variables that cannot be measured experimentally and allow a large number of conditions to be tested before the experimental analysis. However, current simulation models of electromyography (EMG), a core physiological signal in neuromechanical analyses, remain either limited in accuracy and conditions or are computationally heavy to apply. Here, we provide a computational platform to enable future work to overcome these limitations by presenting NeuroMotion, an open-source simulator that can modularly test a variety of approaches to the full-spectrum synthesis of EMG signals during voluntary movements. We demonstrate NeuroMotion using three sample modules. The first module is an upper-limb MSK model with OpenSim API to estimate the muscle fibre lengths and muscle activations during movements. The second module is BioMime, a deep neural network-based EMG generator that receives nonstationary physiological parameter inputs, like the afore-estimated muscle fibre lengths, and efficiently outputs motor unit action potentials (MUAPs). The third module is a motor unit pool model that transforms the muscle activations into discharge timings of motor units. The discharge timings are convolved with the output of BioMime to simulate EMG signals during the movement. We first show how MUAP waveforms change during different levels of physiological parameter variations and different movements. We then show that the synthetic EMG signals during two-degree-of-freedom hand and wrist movements can be used to augment experimental data for regressing joint angles. Ridge regressors trained on the synthetic dataset were directly used to predict joint angles from experimental data. In this way, NeuroMotion was able to generate full-spectrum EMG for the first use-case of human forearm electrophysiology during voluntary hand, wrist, and forearm movements. All intermediate variables are available, which allows the user to study cause-effect relationships in the complex neuromechanical system, fast iterate algorithms before collecting experimental data, and validate algorithms that estimate non-measurable parameters in experiments. We expect this modular platform will enable validation of generative EMG models, complement experimental approaches and empower neuromechanical research.


Assuntos
Biologia Computacional , Eletromiografia , Movimento , Músculo Esquelético , Eletromiografia/métodos , Humanos , Movimento/fisiologia , Músculo Esquelético/fisiologia , Redes Neurais de Computação , Fenômenos Biomecânicos/fisiologia , Simulação por Computador , Potenciais de Ação/fisiologia , Modelos Neurológicos
2.
Cancer ; 128(2): 373-382, 2022 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-34606625

RESUMO

BACKGROUND: Human papillomavirus (HPV)-associated subsequent malignant neoplasms (SMNHPV ) in childhood cancer survivors are poorly understood. METHODS: The cumulative risk of SMNHPV was assessed among 24,363 Childhood Cancer Survivor Study participants. Standardized incidence ratios (SIRs) and absolute excess risk were calculated using age-matched, sex-matched, and calendar year rates from the Surveillance, Epidemiology, and End Results program. Poisson regression models identified SMNHPV risk factors, evaluating relative SIRs (rSIR) and 95% confidence intervals (95% CIs). RESULTS: In total, 46 survivors developed an SMNHPV (median age, 31 years [range, 10-56 years]; median time from primary cancer, 21 years [range, 9-35 years]). SMNHPV sites included oropharynx (N = 44), anorectum (N = 6), uterine cervix (N = 2), and vulva (N = 2). The 33-year cumulative incidence was 0.3% (95% CI, 0.2%-0.4%), and the SIR was nearly 3-fold that of the general population (SIR, 2.86; 95% CI, 2.05-4.00). Female survivors were not at increased risk of cervical or vulvar cancers compared with the general population. All survivors had an elevated risk of oropharyngeal SMNHPV (males: SIR, 4.06; 95% CI, 2.37-6.97; females: SIR, 8.44; 95% CI 4.88-14.61) and anorectal SMNHPV (males: SIR, 13.56; 95% CI, 5.09-36.13; females: SIR, 9.15; 95% CI, 2.29-36.61). Males (vs females: rSIR, 1.99; 95% CI, 1.00-3.94); head, neck, and pelvic radiotherapy doses >3000 centigray (vs none: rSIR, 2.35; 95% CI, 1.11-4.97); and cisplatin-equivalent doses >400 mg/m2 (vs none: rSIR, 4.51; 95% CI, 1.78-11.43) were associated with increased SMNHPV SIRs in multivariable analysis. CONCLUSIONS: Childhood cancer survivors are at increased risk for SMN in sites susceptible to HPV-associated malignancies. Further research examining HPV in the etiology of SMN and the promotion of HPV vaccination and surveillance guidelines for SMNHPV in cancer survivors is warranted.


Assuntos
Alphapapillomavirus , Sobreviventes de Câncer , Segunda Neoplasia Primária , Neoplasias , Neoplasias Vulvares , Adulto , Criança , Feminino , Humanos , Incidência , Masculino , Neoplasias/epidemiologia , Neoplasias/etiologia , Segunda Neoplasia Primária/etiologia , Papillomaviridae , Risco , Fatores de Risco , Programa de SEER , Neoplasias Vulvares/epidemiologia
3.
Pediatr Blood Cancer ; 69(12): e29985, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36114651

RESUMO

BACKGROUND: The SARS-CoV-2 outbreak in 2020 evolved into a global pandemic, and COVID-19 vaccines became rapidly available, including for pediatric patients. However, questions emerged that challenged vaccine acceptance and use. We aimed to answer these questions and give recommendations applicable for use in pediatric patients with cancer by healthcare professionals and the public. METHODS: A 12-member global COVID-19 Vaccine in Pediatric Oncology Working Group made up of physicians and nurses from all world regions met weekly from March to July 2021. We used a modified Delphi method to select the top questions. The Working Group, in four-member subgroups, answered assigned questions by providing brief recommendations, followed by a discussion of the rationale for each answer. All Working Group members voted on each recommendation using a scale of 1 to 10, 10 being complete agreement. A "pass" recommendation corresponded to an agreement ≥7.5. RESULTS: We selected 15 questions from 173 suggested questions. Based on existing published information, we generated answers for each question as recommendations. The overall average agreement for the 24 recommendations was 9.5 (95% CI 9.4-9.6). CONCLUSION: Top COVID-19 vaccine-related questions could be answered using available information. Reports on COVID-19 vaccination and related topics have been published at record speed, aided by available technology and the priority imposed by the pandemic; however, all efforts were made to incorporate emerging information throughout our project. Recommendations will be periodically updated on a dedicated website.


Assuntos
COVID-19 , Neoplasias , Humanos , Criança , Vacinas contra COVID-19 , SARS-CoV-2 , COVID-19/epidemiologia , COVID-19/prevenção & controle , Pandemias/prevenção & controle , Vacinação , Neoplasias/terapia
4.
J Community Health ; 44(3): 492-499, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30989454

RESUMO

Cervical cancer adversely impacts African American communities. While disparities in incidence remain unclear, communities continue to use forums to increase cervical cancer education. The purpose of this paper is to examine the efficacy of using community forums to increase human papillomavirus vaccine (HPVV) and cervical cancer knowledge in African American communities. This study is a one-group pretest-posttest study design using a 17-item questionnaire to collect data from 412 participants in diverse communities. Our analyses revealed perceived knowledge increased significantly after the forums for African American participants. For African Americans, perceived knowledge prior to the forums was explained by gender, access to care, and trust in clinical trials. After the forum, perceived knowledge was associated with access to care and trust in vaccines. Participants who had health insurance reported higher perceived HPV and cervical cancer knowledge and greater trust in vaccines. This study found community forums that address the cultural and historical context of research mistreatment related to HPVV development and include diverse racial/ethnic representation of stakeholders may be a useful strategy to increase HPVV, and cervical cancer knowledge in African American communities.


Assuntos
Negro ou Afro-Americano , Educação em Saúde/métodos , Conhecimentos, Atitudes e Prática em Saúde , Infecções por Papillomavirus/etnologia , Vacinas contra Papillomavirus , Neoplasias do Colo do Útero/etnologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Infecções por Papillomavirus/prevenção & controle , Fatores Socioeconômicos , Inquéritos e Questionários , Confiança , Neoplasias do Colo do Útero/prevenção & controle , Adulto Jovem
5.
Pediatr Blood Cancer ; 63(7): 1244-9, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-26970419

RESUMO

BACKGROUND: The Infectious Diseases Society of America (IDSA) guidelines recommend collecting blood cultures for the first 3 days of febrile neutropenia (FN) in the clinically stable oncology patient with persistent fevers. Nonetheless, many physicians send daily blood cultures beyond 3 days, and the impact of that practice is uncertain. PROCEDURE: We reviewed pediatric FN episodes from July 2009 to May 2014 at University of Chicago Comer Children's Hospital. For each positive culture, we determined if it was a pathogen or a contaminant. We reviewed episode and patient demographics to identify risk factors for subsequent positive blood cultures in the setting of an initially negative culture. RESULTS: We identified 381 episodes of FN in 162 patients. Of those, 87 had a positive blood culture on day 1 (21.0% incidence of bacteremia). Of 294 episodes with a negative blood culture on day 1, six (2.04%, 95% confidence interval [CI] 0.42-3.67) had a positive culture after day 3. Of those, three were pathogens (1.02%, 95%CI -0.14 to 2.18), and only one was found in a hemodynamically stable patient (0.34%, 95%CI -0.33 to 1.01) with new mucositis. In the other two patients, Escherichia coli was isolated from blood cultures after day 10 in the setting of significant hemodynamic changes. Risk factor analysis performed in stable patients yielded nonsignificant results. CONCLUSIONS: Of 294 FN episodes with an initial negative blood culture, only one episode of bacteremia occurred without hemodynamic changes past day 3, supporting the IDSA guidelines to discontinue blood cultures in stable FN patients after day 3.


Assuntos
Bacteriemia , Hemocultura , Neutropenia Febril Induzida por Quimioterapia , Infecções por Escherichia coli , Escherichia coli , Fidelidade a Diretrizes , Adolescente , Bacteriemia/sangue , Bacteriemia/epidemiologia , Bacteriemia/etiologia , Bacteriemia/microbiologia , Neutropenia Febril Induzida por Quimioterapia/sangue , Neutropenia Febril Induzida por Quimioterapia/epidemiologia , Neutropenia Febril Induzida por Quimioterapia/microbiologia , Criança , Pré-Escolar , Infecções por Escherichia coli/sangue , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/etiologia , Infecções por Escherichia coli/microbiologia , Feminino , Humanos , Incidência , Masculino
6.
J Pharm Pharm Sci ; 19(2): 252-73, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27518174

RESUMO

Organogels have emerged as an alternative carrier for small and macromolecules via transdermal, oral, rectal and ophthalmic routes. Pluronic lecithin organogels (PLO gels) are lecithin-based organogels widely used in compounding pharmacies as a vehicle for enhancing the transdermal permeability of many therapeutic drugs. However, the scientific and systematic evidence in support of how well PLO gels help in transdermal delivery is scanty. Recently, some clinical studies have reported nearly complete lack of bioavailability of certain topically administered drugs from PLO gels. The present review aims at summarizing gels and organogels, with a focus on the use of PLO gels in transdermal drug delivery. A special emphasis is placed on controversies looming over the use of PLO gels as a delivery platform for drugs via transdermal route. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.


Assuntos
Sistemas de Liberação de Medicamentos , Lecitinas/química , Poloxâmero/química , Animais , Portadores de Fármacos/química , Géis/química , Humanos , Preparações Farmacêuticas/administração & dosagem
7.
J Community Health ; 41(2): 207-10, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26472436

RESUMO

We set out to assess the feasibility and uptake of an on-site influenza vaccination campaign targeting taxi drivers in airport taxicab lots in Chicago, Illinois. Influenza vaccine was provided by the Chicago Department of Public Health as this event aligned with ongoing efforts to provide influenza vaccinations throughout the city. Clinicians and clinic support staff were volunteers recruited from the University of Chicago Medicine and incorporated nursing staff, physicians, physician residents, and administrative support. Together, this allowed for a cost-effective approach to provide free influenza vaccines to the primarily uninsured taxi driver population. During these events, 545 taxi drivers received influenza vaccine in 2012 while 354 drivers were immunized in 2013. Nearly all drivers reported uninsured or under-insured status. The ability to use volunteers and healthcare organization's desires to meet the needs of the community, in collaboration with often under-staffed but highly dedicated local health departments have the potential to offer valuable public health services to underserved members of the community. Educational initiatives targeting vaccine hesitancy and misinformation may be necessary to improve immunization coverage among this population.


Assuntos
Condução de Veículo , Emigrantes e Imigrantes , Influenza Humana/prevenção & controle , Meios de Transporte , Vacinação/estatística & dados numéricos , Adulto , Idoso , Chicago , Necessidades e Demandas de Serviços de Saúde , Humanos , Masculino , Pessoa de Meia-Idade , Estados Unidos , Adulto Jovem
8.
Saudi Pharm J ; 22(4): 338-42, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25161378

RESUMO

The availability of suppositories in Hungary, especially in clinical pharmacy practice, is usually provided by extemporaneous preparations. Due to the known advantages of rectal drug administration, its benefits are frequently utilized in pediatrics. However, errors during the extemporaneous manufacturing process can lead to non-homogenous drug distribution within the dosage units. To determine the root cause of these errors and provide corrective actions, we studied suppository samples prepared with exactly known errors using both cerimetric titration and HPLC technique. Our results show that the most frequent technological error occurs when the pharmacist fails to use the correct displacement factor in the calculations which could lead to a 4.6% increase/decrease in the assay in individual dosage units. The second most important source of error can occur when the molding excess is calculated solely for the suppository base. This can further dilute the final suppository drug concentration causing the assay to be as low as 80%. As a conclusion we emphasize that the application of predetermined displacement factors in calculations for the formulation of suppositories is highly important, which enables the pharmacist to produce a final product containing exactly the determined dose of an active substance despite the different densities of the components.

9.
IEEE Trans Cybern ; 54(3): 1366-1376, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37467103

RESUMO

Automated source separation algorithms have become a central tool in neuroengineering and neuroscience, where they are used to decompose neurophysiological signal into its constituent spiking sources. However, in noisy or highly multivariate recordings these decomposition techniques often make a large number of errors. Such mistakes degrade online human-machine interfacing methods and require costly post-hoc manual cleaning in the offline setting. In this article we propose an automated error correction methodology using a deep metric learning (DML) framework, generating embedding spaces in which spiking events can be both identified and assigned to their respective sources. Furthermore, we investigate the relative ability of different DML techniques to preserve the intraclass semantic structure needed to identify incorrect class labels in neurophysiological time series. Motivated by this analysis, we propose locality sensitive mining, an easily implemented sampling-based augmentation to typical DML losses which substantially improves the local semantic structure of the embedding space. We demonstrate the utility of this method to generate embedding spaces which can be used to automatically identify incorrectly labeled spiking events with high accuracy.

10.
J Patient Exp ; 11: 23743735241257384, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39050093

RESUMO

The factors influencing caregivers' understanding of pediatric respiratory diseases, such as bronchiolitis, can guide patient care and the acceptability of treatment methods within the healthcare system. This study aims to identify illness perceptions and perform a needs assessment among caregivers of children diagnosed with respiratory diseases. This is a prospective, cross-sectional, questionnaire-driven study of a representative sample of caregivers whose children had an acute respiratory illness. The telephone-administered questionnaire was comprised of (1) demographic items; (2) illness perception questionnaire-revised (IPQ-R); and (3) items about personal barriers, the latter 2 of which employed a 5-point Likert response. Cronbach's alpha (α) was used to measure the internal consistency reliability for each item within the IPQ-R. The Pearson 2-tailed correlation coefficient was used to correlate questionnaire items. We included 75 caregivers whose children have been diagnosed with bronchiolitis (51%), reactive airway disease (RAD) (35%), asthma (33%), and wheezing (44%). We found no significance between the child's diagnosis and the site of recruitment. The most important components of the illness perception were illness coherence (α=0.849), psychological attributions (α=0.903), and barriers to diagnosis (α=0.633). Understanding caregivers' perceptions of respiratory diseases will lead to better treatment acceptance. We must clarify the terms used to define bronchiolitis from viral-induced wheezing, RAD, and the first asthma episode in older infants. Identifying caregivers' gaps in knowledge will help establish a cohesive approach to personalized treatment of respiratory diseases in children and their diagnosis.

11.
Artigo em Inglês | MEDLINE | ID: mdl-39141455

RESUMO

Numerical models of electromyography (EMG) signals have provided a huge contribution to our fundamental understanding of human neurophysiology and remain a central pillar of motor neuroscience and the development of human-machine interfaces. However, while modern biophysical simulations based on finite element methods (FEMs) are highly accurate, they are extremely computationally expensive and thus are generally limited to modeling static systems such as isometrically contracting limbs. As a solution to this problem, we propose to use a conditional generative model to mimic the output of an advanced numerical model. To this end, we present BioMime, a conditional generative neural network trained adversarially to generate motor unit (MU) activation potential waveforms under a wide variety of volume conductor parameters. We demonstrate the ability of such a model to predictively interpolate between a much smaller number of numerical model's outputs with a high accuracy. Consequently, the computational load is dramatically reduced, which allows the rapid simulation of EMG signals during truly dynamic and naturalistic movements.

12.
IEEE Trans Biomed Eng ; PP2024 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-39167512

RESUMO

The decomposition of neurophysiological recordings into their constituent neural sources is of major importance to a diverse range of neuroscientific fields and neuroengineering applications. The advent of high density electrode probes and arrays has driven a major need for novel semi-automated and automated blind source separation methodologies that take advantage of the increased spatial resolution and coverage these new devices offer. Independent component analysis (ICA) offers a principled theoretical framework for such algorithms, but implementation inefficiencies often drive poor performance in practice, particularly for sparse sources. Here we observe that the use of a single non-linear optimization function to identify spiking sources with ICA often has a detrimental effect that precludes the recovery and correct separation of all spiking sources in the signal. We go on to propose a projection-pursuit ICA algorithm designed specifically for spiking sources, which uses a particle swarm methodology to adaptively traverse a polynomial family of non-linearities approximating the asymmetric cumulants of the sources. We robustly prove state-of-the-art decomposition performance on recordings from high density intramuscular probes and demonstrate how the particle swarm quickly finds optimal contrast non-linearities across a range of neurophysiological datasets.

13.
Clin Pediatr (Phila) ; 63(1): 73-79, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-37872735

RESUMO

A retrospective, cross-sectional study of children with bronchiolitis aged 1 to 24 months during an ED visit between 2019 and 2021 was performed. Chi-square or Kruskal-Wallis was used to compare groups. The gamma coefficient was used to measure the association of variables through time. Bronchiolitis cases decreased by 75% from 2019 to 2020 and rose back to prepandemic levels by 2021. Radiographs (gamma -0.443), steroids (gamma -0.298), and bronchodilators (gamma -0.414) decreased during the study period (P < .001). Laboratory studies (gamma 0.032), viral testing (gamma 0.097), antibiotic use (gamma -0.069), and respiratory support (gamma 0.166) were unchanged. The decrease in steroids and bronchodilators was related to a clinical pathway that discouraged their use. Respiratory support remained unchanged. The COVID-19 pandemic (2019-2021) seems to have had little effect on the severity or resource utilization associated with bronchiolitis but may have unraveled a potential bronchiolitis phenotype that may have been more prominent during the pandemic.


Assuntos
Bronquiolite , COVID-19 , Criança , Humanos , Estudos Retrospectivos , Pandemias , Broncodilatadores/uso terapêutico , Estudos Transversais , Hospitais Comunitários , Bronquiolite/tratamento farmacológico , Esteroides/uso terapêutico , Serviço Hospitalar de Emergência
14.
Cancer Causes Control ; 24(8): 1583-93, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23828553

RESUMO

PURPOSE: Prophylactic human papillomavirus (HPV) vaccines and new HPV screening tests, combined with traditional Pap test screening, provide an unprecedented opportunity to greatly reduce cervical cancer in the USA. Despite these advances, thousands of women continue to be diagnosed with and die of this highly preventable disease each year. This paper describes the initiatives and recommendations of national cervical cancer experts toward preventing and possibly eliminating this disease. METHODS: In May 2011, Cervical Cancer-Free America, a national initiative, convened a cervical cancer summit in Washington, DC. Over 120 experts from the public and private sector met to develop a national agenda for reducing cervical cancer morbidity and mortality in the USA. RESULTS: Summit participants evaluated four broad challenges to reducing cervical cancer: (1) low use of HPV vaccines, (2) low use of cervical cancer screening, (3) screening errors, and (4) lack of continuity of care for women diagnosed with cervical cancer. The summit offered 12 concrete recommendations to guide future national and local efforts toward this goal. CONCLUSIONS: Cervical cancer incidence and mortality can be greatly reduced by better deploying existing methods and systems. The challenge lies in ensuring that the array of available prevention options are accessible and utilized by all age-appropriate women-particularly minority and underserved women who are disproportionately affected by this disease. The consensus was that cervical cancer can be greatly reduced and that prevention efforts can lead the way towards a dramatic reduction in this preventable disease in our country.


Assuntos
Programas de Rastreamento/normas , Programas Nacionais de Saúde/normas , Infecções por Papillomavirus/prevenção & controle , Vacinas contra Papillomavirus/uso terapêutico , Guias de Prática Clínica como Assunto , Neoplasias do Colo do Útero/prevenção & controle , Esfregaço Vaginal/normas , Feminino , Humanos , Papillomaviridae/imunologia , Infecções por Papillomavirus/virologia , Prognóstico , Estados Unidos , Neoplasias do Colo do Útero/virologia
15.
Vis Neurosci ; 30(4): 147-52, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24016531

RESUMO

At certain temporal frequencies, the human cone flicker electroretinogram (ERG) contains multiple additional responses following the termination of a flicker train. The purpose of this study was to determine whether these poststimulus responses are a continuing response to the terminated flicker train or represent the oscillation of a resonant system. ERGs were recorded from 10 visually normal adults in response to full-field sinusoidally modulated flicker trains presented against a short-wavelength rod-saturating adapting field. The amplitude and timing properties of the poststimulus responses were evaluated within the context of a model of a second-order resonant system. At stimulus frequencies between 41.7 and 71.4 Hz, the majority of subjects showed at least three additional ERG responses following the termination of the flicker train. The interval between the poststimulus responses was approximately constant across stimulus frequency, with a mean of 14.4 ms, corresponding to a frequency of 69.4 Hz. The amplitude and timing characteristics of the poststimulus ERG responses were well described by an underdamped second-order system with a resonance frequency of 70.3 Hz. The observed poststimulus ERG responses may represent resonant oscillations of retinal ON bipolar cells, as has been proposed for electrophysiological recordings of poststimulus responses from retinal ganglion cells. However, further investigation is required to determine the types of retinal neurons involved in the generation of the poststimulus responses of the human flicker ERG.


Assuntos
Eletrorretinografia , Células Fotorreceptoras Retinianas Cones/fisiologia , Adulto , Algoritmos , Eletrodos Implantados , Potenciais Evocados Visuais/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Neurológicos , Estimulação Luminosa , Células Ganglionares da Retina/fisiologia , Adulto Jovem
16.
Doc Ophthalmol ; 126(1): 9-19, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23054159

RESUMO

BACKGROUND: This study aimed to determine whether the properties of the late negative responses (LNRs) of the electroretinogram (ERG) elicited by sawtooth flicker are consistent with the characteristics of the photopic negative response generated by a light pulse (PhNRpulse). METHODS: ERG recordings were obtained from 10 visually normal individuals and from 6 patients with optic atrophy (OA) in response to 8-Hz rapid-on and rapid-off sawtooth flicker and to brief (4 ms) light pulses. All stimuli were either long wavelength (R), middle wavelength (G), or a combination of equal luminances of long and middle wavelengths (Y) presented on a short-wavelength, rod-saturating adapting field. Amplitudes of LNRs were obtained in response to rapid-on (LNRon) and rapid-off (LNRoff) sawtooth flicker and were also derived from the sum of the ERG waveforms to the two sawtooth phases (LNRadd). RESULTS: For the control subjects, PhNRpulse amplitude varied with stimulus wavelength, being largest in response to a long-wavelength pulse, as expected. However, the amplitudes of LNRon, LNRoff, and LNRadd were not significantly different for R, Y, and G sawtooth flicker. Despite the absence of a chromatic effect, LNRoff and LNRadd amplitudes were significantly smaller in the OA patients than in the controls, similar to the results for the PhNRpulse, implying an inner retinal origin for the LNRoff and LNRadd. However, LNRon amplitudes did not differ significantly between the OA patients and controls, although there was a significant correlation between the LNRon and PhNRpulse for R stimuli. CONCLUSION: We conclude that LNRoff and LNRadd but not LNRon can be useful measures to assess the integrity of the inner retina that can complement the PhNRpulse.


Assuntos
Adaptação Ocular , Visão de Cores/fisiologia , Eletrorretinografia/métodos , Atrofia Óptica/fisiopatologia , Células Fotorreceptoras Retinianas Cones/fisiologia , Adulto , Feminino , Humanos , Interneurônios/fisiologia , Luz , Masculino , Pessoa de Meia-Idade , Atrofia Óptica/diagnóstico , Estimulação Luminosa , Adulto Jovem
17.
Nat Commun ; 14(1): 1600, 2023 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-36959193

RESUMO

Muscle electrophysiology has emerged as a powerful tool to drive human machine interfaces, with many new recent applications outside the traditional clinical domains, such as robotics and virtual reality. However, more sophisticated, functional, and robust decoding algorithms are required to meet the fine control requirements of these applications. Deep learning has shown high potential in meeting these demands, but requires a large amount of high-quality annotated data, which is expensive and time-consuming to acquire. Data augmentation using simulations, a strategy applied in other deep learning applications, has never been attempted in electromyography due to the absence of computationally efficient models. We introduce a concept of Myoelectric Digital Twin - highly realistic and fast computational model tailored for the training of deep learning algorithms. It enables simulation of arbitrary large and perfectly annotated datasets of realistic electromyography signals, allowing new approaches to muscular signal decoding, accelerating the development of human-machine interfaces.


Assuntos
Aprendizado Profundo , Músculo Esquelético , Humanos , Músculo Esquelético/fisiologia , Eletromiografia , Algoritmos , Simulação por Computador
18.
J Neurosci ; 31(11): 3962-7, 2011 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-21411639

RESUMO

Melanoma-associated retinopathy (MAR) is characterized by night blindness, photopsias, and a selective reduction of the electroretinogram b-wave. In certain cases, the serum contains autoantibodies that react with ON bipolar cells, but the target of these autoantibodies has not been identified. Here we show that the primary target of autoantibodies produced in MAR patients with reduced b-wave is the TRPM1 cation channel, the newly identified transduction channel in ON bipolar cells. Sera from two well characterized MAR patients, but not from a control subject, stained human embryonic kidney cells transfected with the TRPM1 gene, and Western blots probed with these MAR sera showed the expected band size (∼180 kDa). Staining of mouse and primate retina with MAR sera revealed immunoreactivity in all types of ON bipolar cells. Similar to staining for TRPM1, staining with the MAR sera was strong in dendritic tips and somas and was weak or absent in axon terminals. This staining colocalized with GFP in Grm6-GFP transgenic mice, where GFP is expressed in all and only ON bipolar cells, and also colocalized with Gα(o), a marker for all types of ON bipolar cells. The staining in ON bipolar cells was confirmed to be specific to TRPM1 because MAR serum did not stain these cells in a Trpm1(-/-) mouse. Evidence suggests that the recognized epitope is likely intracellular, and the sera can be internalized by retinal cells. We conclude that the vision of at least some patients with MAR is compromised due to autoantibody-mediated inactivation of the TRPM1 channel.


Assuntos
Autoanticorpos/metabolismo , Melanoma/imunologia , Células Bipolares da Retina/metabolismo , Doenças Retinianas/imunologia , Canais de Cátion TRPM/metabolismo , Animais , Autoanticorpos/imunologia , Western Blotting , Células HEK293 , Humanos , Masculino , Melanoma/complicações , Camundongos , Camundongos Transgênicos , Doenças Retinianas/etiologia , Canais de Cátion TRPM/genética , Transfecção
19.
Doc Ophthalmol ; 125(1): 21-9, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22581377

RESUMO

Period doubling in the full-field cone flicker electroretinogram (ERG) refers to an alternation in waveform amplitude and/or shape from cycle to cycle, presumably owing to the operation of a nonlinear gain control mechanism. This study examined the influence of stimulus chromatic properties on the characteristics of period doubling in order to better understand the underlying mechanism. ERGs were acquired from 5 visually normal subjects in response to sinusoidally modulated flicker presented at frequencies from 25 to 100 Hz. The test stimuli and the pre-stimulus adaptation were either long wavelength (R), middle wavelength (G), or an equal combination of long and middle wavelengths (Y), all equated for photopic luminance. Fourier analysis was used to obtain the response amplitude at the stimulus frequency F and at a harmonic frequency of 3F/2, which was used as the index of period doubling. The frequency-response function for 3F/2 typically showed two peaks, occurring at approximately 33.3 and 50 Hz. However, the magnitude of period doubling within these frequency regions was dependent on the chromatic properties of both the test stimulus and the pre-stimulus adaptation. Period doubling was generally smallest when an R test was used, even though the stimuli were luminance-equated and the amplitude of F did not differ between the various conditions. The pattern of results indicates that the mechanism that generates period doubling is influenced by chromatic signals from both the test stimulus and the pre-stimulus adaptation, even though the high stimulus frequencies presumably favor the achromatic luminance system.


Assuntos
Visão de Cores/fisiologia , Eletrorretinografia , Luz , Células Fotorreceptoras Retinianas Cones/fisiologia , Adaptação Ocular/fisiologia , Adulto , Feminino , Análise de Fourier , Humanos , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa , Adulto Jovem
20.
Am J Primatol ; 74(1): 1-7, 2012 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-22038875

RESUMO

Chimpanzee responses to the death of a group member have rarely been observed in the wild and most instances involve infant deaths. One of the very few detailed accounts of a group's response to the death of an adult community member is from Gombe National Park, Tanzania, where Teleki [Folia Primatologica 20:81-94, 1973] observed the responses of 16 chimpanzees to an accidental death, none of whom touched the body. Now, almost 40 years later, we report on the behaviors of 16 (different) Gombe individuals to the recently dead body of an adult female community member. In stark contrast to Teleki's account, we observed individual chimpanzees' responses to range from curious observation and passive investigation (e.g. smelling and grooming) to the shaking, dragging, and frustrated beating of the body. Variation across demographic groups is described and may reflect individuals' past experience with death. The implications of our observations are discussed in the context of core morbidity traits shared between humans and chimpanzees.


Assuntos
Morte , Pan troglodytes/psicologia , Comportamento Social , Animais , Feminino , Masculino , Tanzânia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA