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OBJECTIVE: High-caloric diets may slow the progression of amyotrophic lateral sclerosis; however, key macronutrients have not been identified. We examined whether dietary macronutrients are associated with the rate of progression and length of survival among the prospective cohort study participants. METHODS: Participants with a confirmed diagnosis of sporadic amyotrophic lateral sclerosis enrolled in the Multicenter Cohort Study of Oxidative Stress were included (n = 304). We evaluated baseline macronutrient intake assessed by food frequency questionnaire in relation to change in revised amyotrophic lateral sclerosis functional rating scale total-score, and tracheostomy-free survival using linear regression and Cox proportional hazard models. Baseline age, sex, disease duration, diagnostic certainty, body mass index, bulbar onset, revised amyotrophic lateral sclerosis functional rating scale total-score, and forced vital capacity were included as covariates. RESULTS: Baseline higher glycemic index and load were associated with less decline of revised amyotrophic lateral sclerosis functional rating scale total score at 3-month follow-up (ß = -0.13, 95% CI -0.2, -0.01, p = 0.03) and (ß = -0.01, 95% CI -0.03, -0.0007, p = 0.04), respectively. Glycemic index second-quartile, third-quartile, and fourth-quartile groups were associated with less decline at 3 months by 1.9 (95% CI -3.3, -0.5, p = 0.008), 2.0 (95% CI -3.3, -0.6, p = 0.006), and 1.6 (95% CI -3.0, -0.2, p = 0.03) points compared with the first-quartile group; the glycemic load fourth-quartile group had 1.4 points less decline compared with the first-quartile group (95% CI -2.8, 0.1, p = 0.07). Higher glycemic index was associated with a trend toward longer tracheostomy-free survival (HR 0.97, 95% CI 0.93, 1.00, p = 0.07). INTERPRETATION: Higher dietary glycemic index and load are associated with slower disease progression in amyotrophic lateral sclerosis. ANN NEUROL 2024;95:217-229.
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Esclerose Lateral Amiotrófica , Carga Glicêmica , Humanos , Esclerose Lateral Amiotrófica/diagnóstico , Estudos de Coortes , Índice Glicêmico , Estudos Prospectivos , Dieta , Progressão da DoençaRESUMO
INTRODUCTION/AIMS: There are currently no imaging or blood diagnostic biomarkers that can differentiate amyotrophic lateral sclerosis (ALS) from primary lateral sclerosis (PLS) patients early in their disease courses. Our objective is to examine whether patients with PLS can be differentiated from ALS reliably by using plasma lipidome profile and supervised machine learning. METHODS: 40 ALS and 28 PLS patients derived from the Multicenter Cohort study of Oxidative Stress (COSMOS) and 28 healthy control volunteers (CTR) were included. ALS, PLS, and CTR were matched by age and sex. Plasma samples were obtained after overnight fasting. Lipids were extracted from the plasma samples and analyzed using liquid chromatography/mass spectrometry to obtain relative concentrations of 392 lipid species. The lipid data were partitioned into training and testing datasets randomly. An elastic net algorithm was trained using cross-validation to classify PLS vs ALS and PLS vs CTR. Final accuracy was evaluated in the testing dataset. RESULTS: The elastic net model trained with labeled PLS and ALS training lipid dataset demonstrated accuracy (number classified correctly/total number), sensitivity, and specificity of 100% in classifying PLS vs ALS in the unlabeled testing lipid dataset. Similarly, the elastic net model trained with labeled PLS and CTR training lipid datasets demonstrated accuracy, sensitivity, and specificity of 88% in classifying PLS vs CTR in the unlabeled testing lipid dataset. DISCUSSION: Our study suggests PLS patients can be accurately distinguished from ALS and CTR by combining lipidome profile and supervised machine learning without clinical information.
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Esclerose Lateral Amiotrófica , Doença dos Neurônios Motores , Humanos , Esclerose Lateral Amiotrófica/diagnóstico , Lipidômica , Estudos de Coortes , Aprendizado de Máquina , LipídeosRESUMO
INTRODUCTION/AIMS: Factors associated with coronavirus disease 2019 (COVID-19) infection among the myasthenia gravis (MG) population are incompletely understood. This study aimed to characterize the behavior of MG patients during the pandemic and to examine risk factors associated with COVID-19 infection. METHODS: A "COVID-19 Survey" was sent to MG Patient Registry participants in the summer of 2020 (CSS20) and winter of 2021 (CWS21). Survey results were summarized descriptively. Demographics, disease characteristics, medication use, and survey results were compared between those reporting COVID-19 diagnosis (COVID), COVID-19 like symptoms without diagnosis (COVID-Like), and asymptomatic participants. RESULTS: A total of 454 and 665 participants completed the CSS20 and CWS21 surveys respectively; 326 participants completed both. Most continued follow-up visits and MG treatments. The frequency of COVID-like symptoms was similar between CSS20 and CWS21, while COVID-19 exposure (6% vs. 27%), COVID-19 testing among symptomatic individuals (35% vs. 78%), and COVID-19 diagnosis (0.2% vs. 6%) were higher in the CWS21. Cough, fever, fatigue, myalgia, anosmia/ageusia, and hospital and intensive care unit (ICU) admissions were more frequent in the COVID compared to the COVID-Like group. COVID-19 exposure (odds ratio [OR] 7.88), number of people in the household (OR 1.31), and report of MG exacerbation before the pandemic (OR 2.6) were independently associated with COVID-19 infection. DISCUSSION: COVID-19 affected MG patients increasingly through the early pandemic. While face-to-face contact with a COVID-19 infected individual was an obvious risk factor, MG patients who had more people in the household and unstable disease were at elevated risk for COVID-19 infection.
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COVID-19 , Miastenia Gravis , Humanos , COVID-19/epidemiologia , COVID-19/complicações , Pandemias , Teste para COVID-19 , Miastenia Gravis/diagnóstico , Sistema de RegistrosRESUMO
INTRODUCTION/AIMS: Administrative health data has been increasingly used to study the epidemiology of myasthenia gravis (MG) but a case ascertainment algorithm is lacking. We aimed to develop a valid algorithm for identifying MG patients in the older population with Medicare coverage. METHODS: Local older patients (age ≥65) who received healthcare at the Cleveland Clinic and possessed Medicare coverage in 2014 and 2015 were selected. Potential MG patients were identified by using a combination of ICD9 or ICD10 codes for MG and MG-related text-word search. Diagnosis was categorized as "definite MG", "possible MG" or "non-MG" after review of clinical summaries by 5 neuromuscular specialists. Performances of various algorithms were tested by use of the definite MG cohort as a reference standard, and calculation of sensitivity, specificity, and predictive values. RESULTS: A total of 118 988 local older patients with Medicare coverage were identified. Usage of MG ICD codes and text-word search resulted in 125 patients with definite and 67 with possible MG. A total of 45 algorithms involving ICD usage, medication prescription, and specialty visit were tested. The best performing algorithm was identified as 2 office visits using MG ICD codes separated by at least 4 weeks or 1 hospital discharge and 1 office visit each using MG ICD codes separated by at least 4 weeks within the two-year period, resulting in a sensitivity and positive predictive value of 80% for identifying definite MG patients. DISCUSSION: Algorithms using ICD codes can reliably identify patients with MG with a high degree of accuracy.
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Medicare , Miastenia Gravis , Idoso , Algoritmos , Bases de Dados Factuais , Humanos , Classificação Internacional de Doenças , Miastenia Gravis/diagnóstico , Miastenia Gravis/epidemiologia , Valor Preditivo dos Testes , Estados Unidos/epidemiologiaRESUMO
INTRODUCTION/AIMS: We studied the progression of myasthenia gravis (MG) disease burden and medication adjustment among MG Patient Registry participants. METHODS: Participants diagnosed with MG (age ≥18 years), registered between July 1, 2013 and July 31, 2018 and completing both 6- and 12-month follow-up surveys, were included in this investigation. Participants were grouped into high-burden (Myasthenia Gravis Activity of Daily Living scale [MG-ADL] score ≥6) and low-burden (MG-ADL <6) groups based on MG-ADL scores at enrollment. Demographics and disease history were compared between groups. MG-ADL score change and medication changes (escalation, no change, de-escalation) between enrollment and 12-month follow-up were compared between groups. Minimal symptom expression (MSE, MG-ADL <2) at 12 months was compared between groups. Logistic regression analysis was performed to study factors associated with MSE at 12 months. RESULTS: In total, 520 participants (56% female) were included in high-burden (n = 248) and low-burden (n = 272) groups. Those in the high-burden group were more likely to be younger, female, and have shorter disease duration. At 12 months, MSE was achieved in 6% of the high-burden group and newly achieved (42 of 201, 21%) or maintained (52 of 71, 73%) in the low-burden group. In the multivariable analysis, being in the high-burden group and use of pyridostigmine were associated with less likelihood of MSE, whereas MG-ADL score improvement (>2 or >20%) at 6 months significantly increased the likelihood of achieving MSE at 12 months (P = .0004). DISCUSSION: In both groups, but more so in the high-burden group, patients infrequently achieved MSE after 1 year of MG treatment. Baseline low disease burden, improvement at 6 months and no pyridostigmine use were associated with a higher likelihood of MSE at 12 months.
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Atividades Cotidianas , Miastenia Gravis , Adolescente , Efeitos Psicossociais da Doença , Feminino , Seguimentos , Humanos , Masculino , Miastenia Gravis/diagnóstico , Brometo de Piridostigmina/uso terapêutico , Sistema de RegistrosRESUMO
BACKGROUND: The extrapolated reference values procedure (E-Ref) was used to compare data from a single institution with the recently published reference value (RV) for concentric electrode jitter. METHODS: Data from voluntarily activated concentric needle jitter studies in the frontalis muscle were obtained using retrospective chart review. All measured signals were reviewed for acceptable quality. Cutoff values for increased jitter were calculated using E-Ref, and compared with the published RVs. RESULTS: At total of 1501 apparent single-fiber action potential (ASFAP) pairs were reviewed; 1371 ASFAP pairs were determined to have acceptable quality. The cutoff value identified by E-Ref from all reviewed ASFAP pairs was 36 microseconds and the cutoff for acceptable pairs was 35 microseconds. Using either of these cutoff values (36 or 35 microseconds) did not result in a significant difference in percentage of jitter recordings considered normal when compared with the recently published RV (38 microseconds). DISCUSSION: The single-institution jitter cutoff value obtained by E-Ref gives results that are not significantly different from the reported RV.
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Contração Muscular/fisiologia , Fibras Musculares Esqueléticas/fisiologia , Músculo Esquelético/fisiologia , Junção Neuromuscular/fisiologia , Potenciais de Ação/fisiologia , Adulto , Eletrodos , Eletromiografia/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valores de Referência , Estudos RetrospectivosAssuntos
Esclerose Lateral Amiotrófica , Progressão da Doença , Índice Glicêmico , Riluzol , Esclerose Lateral Amiotrófica/tratamento farmacológico , Humanos , Riluzol/uso terapêutico , Riluzol/farmacologia , Índice Glicêmico/efeitos dos fármacos , Fármacos Neuroprotetores/uso terapêutico , Fármacos Neuroprotetores/farmacologia , Glicemia/efeitos dos fármacos , Glicemia/metabolismoRESUMO
INTRODUCTION: Quantitative Myasthenia Gravis (QMG) and Myasthenia Gravis Activities of Daily Living (MG-ADL) scales were compared using the data from the Thymectomy Trial in Non-Thymomatous Myasthenia Gravis Patients Receiving Prednisone Therapy (MGTX) study. METHODS: Correlation between QMG and MG-ADL raw and change-from-baseline scores was calculated every 3 months for 60 months based on treatment groups and minimal manifestation status (MMS). RESULTS: QMG and MG-ADL change-from-baseline scores correlated significantly, with increasing strength of correlation over time, in both treatment groups. QMG and MG-ADL raw scores correlated significantly in both treatment groups, with increasing correlation only in the prednisone-alone group. Correlation between raw scores was weaker in patients who were in MMS, demonstrating a "floor effect" on the MG-ADL scale. Raw QMG scores could be modeled assuming a normal distribution, whereas raw MG-ADL scores could not be modeled this way. DISCUSSION: The floor effect and skewed distribution of the MG-ADL measure should be taken into account in the design of myasthenia gravis clinical trials.
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Atividades Cotidianas , Miastenia Gravis/fisiopatologia , Avaliação de Resultados em Cuidados de Saúde , Terapia Combinada , Glucocorticoides/uso terapêutico , Humanos , Miastenia Gravis/terapia , Prednisona/uso terapêutico , Ensaios Clínicos Controlados Aleatórios como Assunto , TimectomiaRESUMO
INTRODUCTION: Our aim in this study was to identify the prevalence and clinical characteristics of LRP4/agrin-antibody-positive double-seronegative myasthenia gravis (DNMG). METHODS: DNMG patients at 16 sites in the United States were tested for LRP4 and agrin antibodies, and the clinical data were collected. RESULTS: Of 181 DNMG patients, 27 (14.9%) were positive for either low-density lipoprotein receptor-related protein 4 (LRP4) or agrin antibodies. Twenty-three DNMG patients (12.7%) were positive for both antibodies. More antibody-positive patients presented with generalized symptoms (69%) compared with antibody-negative patients (43%) (P ≤ .02). Antibody-positive patients' maximum classification on the Myasthenia Gravis Foundation of America (MGFA) scale was significantly higher than that for antibody-negative patients (P ≤ .005). Seventy percent of antibody-positive patients were classified as MGFA class III, IV, or V compared with 39% of antibody-negative patients. Most LRP4- and agrin-antibody-positive patients (24 of 27, 89%) developed generalized myathenia gravis (MG), but with standard MG treatment 81.5% (22 of 27) improved to MGFA class I or II during a mean follow-up of 11 years. DISCUSSION: Antibody-positive patients had more severe clinical disease than antibody-negative patients. Most DNMG patients responded to standard therapy regardless of antibody status.
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Agrina/imunologia , Autoanticorpos , Proteínas Relacionadas a Receptor de LDL/imunologia , Miastenia Gravis/diagnóstico , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Miastenia Gravis/epidemiologia , Miastenia Gravis/imunologia , Prevalência , Avaliação de Sintomas , Estados UnidosRESUMO
INTRODUCTION: Herein we report our experience with the repetitive nerve stimulation (RNS) test in myasthenia gravis (MG) crisis. METHODS: The various parameters of the RNS tests in 26 patients with MG crisis were analyzed. RESULTS: In 18 (69%) patients, MG crisis is the first manifestation of MG. RNS tests were abnormal in 24 (92%) patients by decrement at low-rate stimulation in any of 4 tested muscles. Three patterns of abnormality were found: MG pattern (decrement at low-rate stimulation) in 23 patients; Lambert-Eaton myasthenic syndrome pattern in 1 patient; and cholinergic crisis pattern in 1 patient. DISCUSSION: During MG crisis, the RNS test can serve as a rapid and sensitive diagnostic tool for MG in a majority of patients. Muscle Nerve 59:544-544, 2019.
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Potenciais de Ação , Síndrome Miastênica de Lambert-Eaton/diagnóstico , Miastenia Gravis/diagnóstico , Adulto , Idoso , Técnicas de Diagnóstico Neurológico , Progressão da Doença , Estimulação Elétrica/métodos , Eletromiografia/métodos , Feminino , Humanos , Síndrome Miastênica de Lambert-Eaton/fisiopatologia , Masculino , Pessoa de Meia-Idade , Miastenia Gravis/fisiopatologia , Nervos PeriféricosRESUMO
INTRODUCTION: This study sought to evaluate needle electromyography (EMG) practice patterns among electromyographers with patients taking novel oral anticoagulants (NOAC). METHODS: A survey questionnaire was sent to members of the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) via email web link. Anonymous survey responses were collected through an online website. RESULTS: Fifty-eight AANEM members responded, 28 (48%) of whom worked at a teaching hospital and 30 (52%) of whom worked in a private setting. Fifty-four (93%) responders perform needle EMG on patients taking NOACs. Twenty-nine (50%) responders examine paraspinal muscles, and 20 (40%) responders examine facial muscles. Among 14 responders who perform single-fiber EMG (SFEMG), 8 examine patients taking NOACs. DISCUSSION: Although most of the electromyographers perform needle EMG on patients taking NOACs, they reported variable practice patterns in examination of the paraspinal and facial muscles and in performing SFEMG. A prospective risk-benefit study is required. Muscle Nerve 58: 307-309, 2018.
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Anticoagulantes/efeitos adversos , Eletromiografia/efeitos adversos , Eletromiografia/métodos , Agulhas , Estudos Transversais , Músculos Faciais/fisiopatologia , Hemorragia/epidemiologia , Hemorragia/etiologia , Humanos , Músculo Esquelético/fisiopatologia , Estudos Prospectivos , Medição de Risco , Inquéritos e QuestionáriosRESUMO
INTRODUCTION: Quality of life (QOL) has been poorly characterized among patients with myasthenia gravis (MG) other than assessments performed within the clinical setting. METHODS: Patients age ≥ 18 years who were diagnosed with MG and registered with the MG patient registry between July 1, 2013, and June 30, 2016, were included. Demographic information, disease related history, and QOL were compared between men and women using multivariable analysis. RESULTS: A total of 1,315 subjects (827 women) were included. Women were significantly younger, had a younger age at symptom onset, and were more likely to have thymoma and thymectomy. The 15-item Myasthenia Gravis Quality of Life scale (MG-QOL15) was significantly worse in women. MG-QOL15 score was comparable between women who had thymectomy and men with or without thymectomy. DISCUSSION: QOL among MG patients is worse in women compared with men, but this disparity is eliminated in women who have undergone thymectomy. Muscle Nerve, 2018.
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The interactions of energetic ions with multi-cation compounds and their consequences in terms of changes in the local electronic structure, which may facilitate intriguing hybridization between O 2p and metal d orbitals and magnetic ordering, are the subject of debate and require a deep understanding of energy transfer processes and magnetic exchange mechanisms. In this study, nanocrystals of ZnFe2O4 were exposed to O7+ ions with an energy of 100 MeV to understand, qualitatively and quantitatively, the metal-ligand field interactions, cation migration and magnetic exchange interactions by employing X-ray absorption fine structure measurements and X-ray magnetic circular dichroism to get deeper mechanistic insights. Nanosized zinc ferrite nanoparticles (NPs) with a size of â¼16 nm synthesized in the cubic spinel phase exhibited deterioration of the crystalline phase when 100 MeV O7+ ions passed through them. However, the size of these NPs remained almost the same. The behaviour of crystal deterioration is associated with the confinement of heat in this interaction. The energy confined inside the nanoparticles promotes cation redistribution as well as the modification of the local electronic structure. Prior to this interaction, almost 42% of Zn2+ ions occupied AO4 tetrahedra; however, this value increased to 63% after the interaction. An inverse effect was observed for metal ion occupancies in BO6 octahedra. The L-edge spectra of Fe and Zn reveal that the spin and valence states of the metal ions were not affected by this interaction. This effect is also supported by K-edge measurements for Fe and Zn. The t2g/eg intensity ratio in the O K-edge spectra decreased after this interaction, which is associated with detachment of Zn2+ ions from the lattice. The extent of hybridization, as estimated from the ratio of the post-edge to the pre-edge region of the O K-edge spectra, decreased after this interaction. The metal-oxygen and metal-metal bond lengths were modified as a result of this interaction, as determined from extended X-ray absorption fine structure measurements. These measurements further support the observation of cation migration from AO4 tetrahedra to AO6 octahedra and vice versa. The Fe L-edge magnetic circular dichroism spectra indicate that Fe3+ ions occupying sites in AO4 tetrahedra and BO6 octahedra exhibited antiferromagnetic-like ordering prior to this interaction. The NPs that interacted with energetic O ions displayed a different kind of magnetic ordering.
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Anemia Falciforme/complicações , Debilidade Muscular/etiologia , Músculo Esquelético/patologia , Miastenia Gravis/diagnóstico , Proteínas Tirosina Quinases/imunologia , Autoanticorpos/sangue , Análise Química do Sangue , Diagnóstico Diferencial , Dispneia/etiologia , Estimulação Elétrica , Feminino , Humanos , Imunoglobulinas Intravenosas/uso terapêutico , Transtornos de Enxaqueca/complicações , Doença de Moyamoya/etiologia , Músculo Esquelético/imunologia , Músculo Esquelético/fisiopatologia , Miastenia Gravis/complicações , Miastenia Gravis/tratamento farmacológico , Miastenia Gravis/patologia , Adulto JovemRESUMO
Al-, Ga-, and In-doped ZnO thin films are widely used in many technical applications, such as in solar cells and on transparent conducting oxides having high optical transmission and low resistivity values. We prepared SnO2-doped ZnO thin films on quartz substrates by using an RF magnetron sputtering method at a substrate temperature of 350 degrees C. The ratio of SnO2 to ZnO was varied from 0 to 5:5 to investigate the effects of Sn on structure and physical properties of ZnO film. The samples were synthesized at a base pressure of 1.3 x 10(-4) Pa with a working pressure of 1.3 Pa and an RF power of 40 W under Ar atmosphere. The results of X-ray diffraction data revealed that pure ZnO films exhibit a strong (002) orientation and a polycrystalline wurzite hexagonal structure. However, as increasing the SnO2 concentration, ZnO transforms to an amorphous phase. The results of the Hall-effect-measurement system revealed that the resistivity values of the films increased as increasing the doping level of SnO2. The AFM data of morphology and microstructure showed that the grain size decreased with increasing SnO2 contents while the total area of grain the boundary increased. The average value of the transmittance of the films in the visible light range was 80-95% and was shifted toward to the shorter wavelengths of the absorption edges with increasing SnO2 contents.
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Ondas de Rádio , Compostos de Estanho/química , Óxido de Zinco/química , Microscopia de Força Atômica , Difração de Raios XRESUMO
OBJECTIVE: Stress is the most commonly reported precipitant of epileptic seizures, but the mechanism by which stress precipitates seizures and the risk factors for stress as a seizure precipitant are poorly understood. Previously, we observed higher levels of anxiety symptoms in patients with epilepsy who reported stress as a seizure precipitant. Given that childhood trauma increases the risk of general psychiatric symptom burden, including anxiety symptoms, we sought to examine the relationship between childhood adversity and stress as a seizure precipitant. METHODS: Sequential outpatients (N=236) evaluated at the Epilepsy Center of the University of Cincinnati Neuroscience Institute who had previously enrolled in an earlier study of stress and seizures were enrolled. Subjects either endorsed stress as a seizure precipitant [Stress (+)] or not [Stress (-)]. The Childhood Trauma Questionnaire Short Form (CTQ-SF), a 28-question scale that evaluates 5 domains of childhood adversity (physical abuse, physical neglect, emotional abuse, emotional neglect, and sexual abuse) was sent via mail and returned on paper or electronically from participants. Total CTQ-SF score and CTQ-SF domain scores were compared between Stress (+) and Stress (-) groups using Wilcoxon rank sum test. Spearman's rank correlation between CTQ-SF scores with depression and anxiety was also determined, and these analyses were followed by a multivariate analysis to identify the association of childhood trauma with other factors including anxiety and depression. RESULTS: A total of 119 out of 236 CTQ-SFs that were sent out were completed. Response rates were 91/195 for Stress (+) and 28/41 for Stress (-). The Stress (+) group reported higher scores in emotional abuse compared with the Stress (-) group (p=0.029); CTQ-SF total scores were higher in the Stress (+) group compared with the Stress (-) group (p=0.08), and sexual abuse scores were higher in Stress (+) group (p=0.07), but there were no statistically significant differences for other types of trauma. Depression and anxiety scores were higher in the Stress (+) group, but anxiety was the only independent factor associated with the Stress (+) group in the multivariate analysis (p=0.0021). CONCLUSION: Patients with epilepsy who report stress as a seizure precipitant are more likely to endorse a history of childhood traumatic experiences, particularly emotional abuse, compared with those who do not perceive stress as a precipitant. Further study is needed to identify how childhood trauma interacts with anxiety in modulating stress response in patients with epilepsy.
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Maus-Tratos Infantis/psicologia , Convulsões/etiologia , Convulsões/psicologia , Autorrelato , Estresse Psicológico/complicações , Estresse Psicológico/psicologia , Adulto , Ansiedade/complicações , Ansiedade/diagnóstico , Ansiedade/psicologia , Criança , Estudos de Coortes , Depressão/complicações , Depressão/diagnóstico , Depressão/psicologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Convulsões/diagnóstico , Estresse Psicológico/diagnóstico , Inquéritos e QuestionáriosRESUMO
An in-vacuum undulator (IVU) with a tapered configuration was installed in the 8C nanoprobe/XAFS beamlime (BL8C) of the Pohang Light Source in Korea for hard X-ray nanoprobe and X-ray absorption fine-structure (XAFS) experiments. It has been operated in planar mode for the nanoprobe experiments, while gap-scan and tapered modes have been used alternatively for XAFS experiments. To examine the features of the BL8C IVU for XAFS experiments, spectral distributions were obtained theoretically and experimentally as functions of the gap and gap taper. Beam profiles at a cross section of the X-ray beam were acquired using a slit to visualize the intensity distributions which depend on the gap, degree of tapering and harmonic energies. To demonstrate the effect of tapering around the lower limit of the third-harmonic energy, V K-edge XAFS spectra were obtained in each mode. Owing to the large X-ray intensity variation around this energy, XAFS spectra of the planar and gap-scan modes show considerable spectral distortions in comparison with the tapered mode. This indicates that the tapered mode, owing to the smooth X-ray intensity profile at the expense of the highest and most stable intensity, can be an alternative for XAFS experiments where the gap-scan mode gives a considerable intensity variation; it is also suitable for quick-XAFS scanning.