Assuntos
Imageamento por Ressonância Magnética , Transtornos Parkinsonianos , Humanos , Transtornos Parkinsonianos/diagnóstico por imagem , Transtornos Parkinsonianos/etiologia , Uremia/complicações , Masculino , Globo Pálido/diagnóstico por imagem , Globo Pálido/patologia , Síndrome , Feminino , Pessoa de Meia-IdadeRESUMO
Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective therapeutic strategy for motor symptoms of Parkinson's disease (PD) when L-DOPA therapy induces disabling side effects. Classical inflammatory activation of glial cells is well established in PD, contributing to the progressive neurodegenerative state; however, the role of DBS in regulating the inflammatory response remains largely unknown. To understand the involvement of astrocytes in the mechanisms of action of DBS, we evaluated the effect of STN-DBS in regulating motor symptoms, astrocyte reactivity, and cytokine expression in a 6-OHDA-induced PD rat model. To mimic in vivo DBS, we investigate the effect of high-frequency stimulation (HFS) in cultured astrocytes regulating cytokine induction and NF-κB activation. We found that STN-DBS improved motor impairment, induced astrocytic hyperplasia, and reversed increased IFN-γ and IL-10 levels in the globus pallidus (GP) of lesioned rats. Moreover, HFS activated astrocytes and prevented TNF-α-induced increase of monocyte chemoattractant protein-1 (MCP-1) and NF-κB activation in vitro. Our results indicate that DBS/HFS may act as a regulator of the inflammatory response in PD states, attenuating classical activation of astrocytes and cytokine induction, potentially through its ability to regulate NF-κB activation. These findings may help us understand the role of astrocyte signaling in HFS, highlighting its possible relationship with the effectiveness of DBS in neurodegenerative disorders.
Assuntos
Astrócitos/patologia , Estimulação Encefálica Profunda , Doença de Parkinson/patologia , Núcleo Subtalâmico/patologia , Animais , Modelos Animais de Doenças , Estimulação Elétrica , Globo Pálido/patologia , Hiperplasia , Inflamação/patologia , Masculino , Camundongos , Atividade Motora , NF-kappa B/metabolismo , Ratos Wistar , Transdução de Sinais , Fator de Necrose Tumoral alfa/farmacologiaRESUMO
Introduction: Recently, some studies have reported accumulation of gadolinium in the brain of patients with multiple administrations of gadolinium-based contrast. Patients with multiple sclerosis are subjected to multiple contrasting resonances and could become a population at risk. Objective: To determine whether repeated intravenous exposure to gadolinium is associated with more intensity in the thalamus, dentate nucleus, pons and the globus pallidus. Methods: A retrospective study of 60 patients with MS who had undergone two or more contrasted MRs between 2007 and 2015, was performed. The ratios calculated were: dentate nuclei-to-pons (DNP), thalamus-to-pons (TP), caudate nuclei-to-pons (CNP), globus pallidus-to-thalamus (GPT), globus pallidus-to-pons (GPP), by reviewing simple T1 axial sequences. Relative changes were calculated and compared with the number of contrasted MRs. The concordance between observers and the intraclass correlation coefficient was evaluated. Results: There was no evidence of increased signal intensity in T1 sequences (DNP 0.524, GPT 0.466, GPP 0.684, TP 0.771, CNP 0.352). As there were no differences, the Spearman coefficient showed no correlation between relative changes and the number of resonances performed. Inter-observer agreement was almost perfect (0.982) for all structures. Conclusion: Our study did not find a statistically significant increase in the T1 signal intensity in patients with multiple sclerosis. However, there are factors to consider, such as the type of gadolinium and the time lapse between administrations.
Introducción: Recientemente, algunos estudios han informado acumulación de gadolinio en el cerebro de los pacientes con múltiples administraciones de contraste basado en gadolinio. Los pacientes con esclerosis múltiple son sometidos a múltiples resonancias contrastadas y podrían convertirse en una población de riesgo. Objetivo: Determinar si la exposición repetida por vía intravenosa a gadolino se asocia con mayor intensidad en el tálamo, el dentado, el puente y el globo pálido. Métodos: Se realizó un estudio retrospectivo núcleo de 60 pacientes con EM que habían sido sometidos a dos o más RM contrastadas entre 2007 - 2015. Se calcularon las razones núcleo dentado - puente (DNP), tálamo-puente (TP), núcleo caudado- puente (CNP), globus pallidus - tálamo (GPT), globus pallidos - puente (GPP), revisando secuencias T1 axiales simples. Se calcularon los cambios relativos y se compararon con el número de RM contrastadas. Se evaluó la concordancia entre observadores con el coeficiente de correlación intraclase. Resultados: No hubo evidencia de aumento de la intensidad de la señal en secuencias T1 (DNP 0,524, 0,446 GPT, GPP 0,684, 0,771 PT, CNP 0.352). Al no existir diferencias, el coeficiente de Spearman no mostró correlación entre los cambios relativos y el número de resonancias realizadas. La concordancia interobservador fue casi perfecta (0.982) para todas las estructuras. Conclusión: Nuestro estudio no encontró un aumento estadísticamente significativo en la intensidad de la señal T1 en pacientes con esclerosis múltiple. Sin embargo, hay factores a considerar, tales como el tipo de gadolinio y el lapso de tiempo entre las administraciones.
Assuntos
Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Meios de Contraste/administração & dosagem , Gadolínio DTPA/administração & dosagem , Esclerose Múltipla/diagnóstico , Núcleos Cerebelares/patologia , Globo Pálido/patologia , Imageamento por Ressonância Magnética , Esclerose Múltipla/patologia , Estudos Retrospectivos , Tálamo/patologiaAssuntos
Imagem de Difusão por Ressonância Magnética/métodos , Embolia Gordurosa/complicações , Embolia Gordurosa/diagnóstico por imagem , Papiledema/diagnóstico por imagem , Papiledema/etiologia , Idoso , Embolia Gordurosa/patologia , Feminino , Globo Pálido/diagnóstico por imagem , Globo Pálido/patologia , Humanos , Embolia Intracraniana/complicações , Embolia Intracraniana/diagnóstico por imagem , Embolia Intracraniana/patologia , Papiledema/patologia , Retina/diagnóstico por imagem , Retina/patologiaRESUMO
PURPOSE: To evaluate whether human immunodeficiency virus (HIV)-positive patients with and without executive functions deficits and healthy control subjects differ on cortical thickness and subcortical brain structures volume in vivo. METHODS: In total, 34 HIV-positive patients with executive functions deficits were compared with 13 HIV-positive patients without executive functions deficits and 19 gender-, age-, and education-matched control subjects. Executive functions impairments were classified by performance on the Wisconsin card sorting test. T1 3-dimensional magnetization prepared rapid gradient echo-weighted imaging was performed using a 1.5 Tesla (magnetic resonance) MR scanner. FreeSurfer software was used to perform cortical reconstruction and volumetric segmentation of subcortical gray matter structures. RESULTS: HIV-positive patients with executive functions deficits had smaller volumes in the right and left caudate compared with the HIV-positive patients without executive functions deficits and control groups. In addition, HIV-positive patients with executive functions deficits had smaller volumes in their left accumbens, right putamen, and globus pallidum compared with the control group. No significant differences in cortical thickness were observed between the groups. CONCLUSION: HIV-positive patients with executive functions deficits have reduced volumes of several subcortical structures, primarily in the caudate nucleus.
Assuntos
Complexo AIDS Demência/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Função Executiva/fisiologia , Substância Cinzenta/diagnóstico por imagem , Soropositividade para HIV/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Complexo AIDS Demência/patologia , Adulto , Idoso , Encéfalo/patologia , Brasil , Núcleo Caudado/diagnóstico por imagem , Núcleo Caudado/patologia , Córtex Cerebral/diagnóstico por imagem , Córtex Cerebral/patologia , Feminino , Globo Pálido/diagnóstico por imagem , Globo Pálido/patologia , Substância Cinzenta/patologia , Soropositividade para HIV/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Tamanho do Órgão , Putamen/diagnóstico por imagem , Putamen/patologiaRESUMO
Infants with chronic bilirubin encephalopathy often demonstrate abnormal bilateral, symmetric, high-signal intensity on T2-weighted magnetic resonance imaging of the globus pallidus and subthalamic nucleus, consistent with the neuropathology of kernicterus. Early magnetic resonance imaging of at-risk infants, while frequently showing increased T1-signal in these regions, may give false-positive findings due to the presence of myelin in these structures. Advanced magnetic resonance imaging including diffusion-weighted imaging, magnetic resonance spectroscopy, and diffusion tensor imaging with tractography may shed new insights into the pathogenesis of bilirubin-induced brain injury and the neural basis of long-term disability in infants and children with chronic bilirubin encephalopathy.
Assuntos
Encéfalo/patologia , Kernicterus/patologia , Imageamento por Ressonância Magnética/métodos , Imageamento por Ressonância Magnética/tendências , Doença Aguda , Animais , Bilirrubina , Doença Crônica , Imagem de Difusão por Ressonância Magnética , Modelos Animais de Doenças , Reações Falso-Positivas , Globo Pálido/patologia , Humanos , Lactente , Recém-Nascido , Recém-Nascido Prematuro , Doenças do Prematuro , Espectroscopia de Ressonância Magnética , Ratos , Núcleo Subtalâmico/patologiaRESUMO
PURPOSE: To quantify involvement of globus pallidus and two midbrain nuclei (substantia nigra and red nucleus) in Pantothenate Kinase-Associated Neurodegeneration (PKAN). MATERIAL AND METHODS: We performed T2 and T2* weighted imaging with calculation of the corresponding relaxation times on a subset of 5 patients from a larger group of 20 patients with PKAN from the southwest part of the Dominican Republic. Examinations were carried out on a 3T scanner and included a multi-echo spin-echo as well as a multi-echo gradient echo sequence. Results were compared to a control group of 19 volunteers. RESULTS: T2 and T2* weighted sequences showed abnormal signal reduction in the globus pallidus of all patients. On T2* weighted imaging, abnormal signal in the substantia nigra could reliably be detected in 75% of cases, but differentiation from normal was less reliable in T2 weighted scans. Correspondingly, relaxation times differed from normal with very high significance (p < 0.0001) in the globus pallidus, but with with less significance in the substantia nigra (p ≤ 0.03). The red nucleus was not affected. CONCLUSIONS: Signal reduction in the globus pallidus, which probably is due to abnormal accumulation of iron, is severe in PKAN and can be differentiated from normal with high reliability. The substantia nigra is affected to a lesser degree, and the red nucleus is not involved. The reason for this selective susceptibility of normally iron-rich brain structures for pathological accumulation of iron remains speculative. Our quantitative results might be helpful to assess the value of an iron chelation approach to therapy.
Assuntos
Globo Pálido/patologia , Interpretação de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Mesencéfalo/patologia , Neurodegeneração Associada a Pantotenato-Quinase/patologia , Adolescente , Feminino , Humanos , Masculino , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Adulto JovemRESUMO
The ether à go-go (Eag) gene encodes the voltage-gated potassium (K(+)) ion channel Kv10.1, whose function still remains unknown. As dopamine may directly affect K(+) channels, we evaluated whether a nigrostriatal dopaminergic lesion induced by the neurotoxin 6-hydroxydopamine (6-OHDA) would alter Eag1-K(+) channel expression in the rat basal ganglia and related brain regions. Male Wistar rats received a microinjection of either saline or 6-OHDA (unilaterally) into the medial forebrain bundle. The extent of the dopaminergic lesion induced by 6-OHDA was evaluated by apomorphine-induced rotational behavior and by tyrosine hydroxylase (TH) immunoreactivity. The 6-OHDA microinjection caused a partial or complete lesion of dopaminergic cells, as well as a reduction of Eag1+ cells in a manner proportional to the extent of the lesion. In addition, we observed a decrease in TH immunoreactivity in the ipsilateral striatum. In conclusion, the expression of the Eag1-K(+)-channel throughout the nigrostriatal pathway in the rat brain, its co-localization with dopaminergic cells and its reduction mirroring the extent of the lesion highlight a physiological circuitry where the functional role of this channel can be investigated. The Eag1-K(+) channel expression in dopaminergic cells suggests that these channels are part of the diversified group of ion channels that generate and maintain the electrophysiological activity pattern of dopaminergic midbrain neurons.
Assuntos
Gânglios da Base/metabolismo , Neurônios Dopaminérgicos/metabolismo , Canais de Potássio Éter-A-Go-Go/metabolismo , Degeneração Neural/metabolismo , Oxidopamina/toxicidade , Transtornos Parkinsonianos/metabolismo , Animais , Gânglios da Base/efeitos dos fármacos , Gânglios da Base/patologia , Modelos Animais de Doenças , Neurônios Dopaminérgicos/efeitos dos fármacos , Neurônios Dopaminérgicos/patologia , Globo Pálido/efeitos dos fármacos , Globo Pálido/metabolismo , Globo Pálido/patologia , Imuno-Histoquímica , Masculino , Degeneração Neural/induzido quimicamente , Núcleo Accumbens/efeitos dos fármacos , Núcleo Accumbens/metabolismo , Núcleo Accumbens/patologia , Transtornos Parkinsonianos/induzido quimicamente , Ratos , Ratos Wistar , Substância Negra/efeitos dos fármacos , Substância Negra/metabolismo , Substância Negra/patologia , Simpatolíticos/toxicidade , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
Exponential decay of the power spectrum is typically observed in turbulent flow patterns, as evidenced both in experiments and in the Navier-Stokes equations describing fluid dynamics. In this study, we present evidence on the exponential decay of power spectra belonging to interspike interval time series, registered in pallidal neurons from patients with Parkinson's disease. Extracellular neuronal recordings were obtained during functional neurosurgery and processed off-line. Interspike interval power spectra were calculated for single unit recordings. All power spectra analyzed were similar, presenting rapid decay of power with frequency. Regression coefficient (adjusted R squared) for exponential function fit was very high, over 0.99 (p<0.001) in every case. We therefore suggest that the neurons studied here show turbulent-like behavior from a spectral point of view, and theorize that Navier-Stokes-like equations may be potentially useful tools to model spectral patterns of firing activity in neurons of this type. We propose to classify neural systems according to the general form of their power spectrum into two major groups of physical systems: systems with scale invariance and a power-law behavior of the power spectrum, and systems with critical scale and an exponential decay of the power spectrum.