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1.
J Neurophysiol ; 131(3): 541-547, 2024 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-38264793

RESUMO

Transcranial magnetic stimulation (TMS) causes repetitive spinal motoneuron discharges (repMNDs), but the effects of short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) on repMNDs remain unknown. Triple stimulation technique (TST) and the extended TST-protocols that include a fourth and fifth stimulation, the Quadruple (QuadS) and Quintuple (QuintS) stimulation, respectively, offer a precise estimate of cortical and spinal motor neuron discharges, including repMNDs. The objective of our study was to explore the effects of SICI and ICF on repMNDs. We explored conventional paired-pulse TMS protocols of SICI and ICF with the TMS, TST, the QuadS, and the QuintS protocols, in a randomized study design in 20 healthy volunteers. We found significantly less repMNDs in the SICI paradigm compared with a single-pulse TMS (SP-TMS). No significant difference was observed in the ICF paradigm. There was a significant inter- and intrasubject variability in both SICI and ICF. We demonstrate a significant reduction of repMNDs in SICI, which may result from the suppression of later I-waves and mediate the inhibition of motor-evoked potential (MEP). There is no increase in repMNDs in ICF suggesting another mechanism underlying facilitation. This study provides the proof that a reduction of repMNDs mediates the inhibition seen in SICI.NEW & NOTEWORTHY Significant reduction of repetitive motor neuron discharges (repMNDs) in short-interval intracortical inhibition (SICI) may result from the suppression of later I-waves and mediate the inhibition of motor-evoked potential (MEP). There is no change in the number of repMNDs in intracortical facilitation (ICF). There was a significant variability in SICI and ICF in healthy subjects.


Assuntos
Córtex Motor , Estimulação Magnética Transcraniana , Humanos , Eletromiografia , Potencial Evocado Motor/fisiologia , Córtex Motor/fisiologia , Neurônios Motores , Inibição Neural/fisiologia , Estimulação Magnética Transcraniana/métodos
2.
Oncologist ; 2024 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-39401002

RESUMO

Tumor Treating Fields (TTFields) therapy is a locoregional, anticancer treatment consisting of a noninvasive, portable device that delivers alternating electric fields to tumors through arrays placed on the skin. Based on efficacy and safety data from global pivotal (randomized phase III) clinical studies, TTFields therapy (Optune Gio) is US Food and Drug Administration-approved for newly diagnosed (nd) and recurrent glioblastoma (GBM) and Conformité Européenne-marked for grade 4 glioma. Here we review data on the multimodal TTFields mechanism of action that includes disruption of cancer cell mitosis, inhibition of DNA replication and damage response, interference with cell motility, and enhancement of systemic antitumor immunity (adaptive immunity). We describe new data showing that TTFields therapy has efficacy in a broad range of patients, with a tolerable safety profile extending to high-risk subpopulations. New analyses of clinical study data also confirmed that overall and progression-free survival positively correlated with increased usage of the device and dose of TTFields at the tumor site. Additionally, pilot/early phase clinical studies evaluating TTFields therapy in ndGBM concomitant with immunotherapy as well as radiotherapy have shown promise, and new pivotal studies will explore TTFields therapy in these settings. Finally, we review recent and ongoing studies in patients in pediatric care, other central nervous system tumors and brain metastases, as well as other advanced-stage solid tumors (ie, lung, ovarian, pancreatic, gastric, and hepatic cancers), that highlight the broad potential of TTFields therapy as an adjuvant treatment in oncology.

3.
Schizophr Res ; 167(1-3): 18-27, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25601362

RESUMO

Perineuronal nets (PNNs) were shown to be markedly altered in subjects with schizophrenia. In particular, decreases of PNNs have been detected in the amygdala, entorhinal cortex and prefrontal cortex. The formation of these specialized extracellular matrix (ECM) aggregates during postnatal development, their functions, and association with distinct populations of GABAergic interneurons, bear great relevance to the pathophysiology of schizophrenia. PNNs gradually mature in an experience-dependent manner during late stages of postnatal development, overlapping with the prodromal period/age of onset of schizophrenia. Throughout adulthood, PNNs regulate neuronal properties, including synaptic remodeling, cell membrane compartmentalization and subsequent regulation of glutamate receptors and calcium channels, and susceptibility to oxidative stress. With the present paper, we discuss evidence for PNN abnormalities in schizophrenia, the potential functional impact of such abnormalities on inhibitory circuits and, in turn, cognitive and emotion processing. We integrate these considerations with results from recent genetic studies showing genetic susceptibility for schizophrenia associated with genes encoding for PNN components, matrix-regulating molecules and immune system factors. Notably, the composition of PNNs is regulated dynamically in response to factors such as fear, reward, stress, and immune response. This regulation occurs through families of matrix metalloproteinases that cleave ECM components, altering their functions and affecting plasticity. Several metalloproteinases have been proposed as vulnerability factors for schizophrenia. We speculate that the physiological process of PNN remodeling may be disrupted in schizophrenia as a result of interactions between matrix remodeling processes and immune system dysregulation. In turn, these mechanisms may contribute to the dysfunction of GABAergic neurons.


Assuntos
Encéfalo/patologia , Interneurônios/patologia , Interneurônios/fisiologia , Esquizofrenia/patologia , Animais , Matriz Extracelular/patologia , Humanos , Ácido gama-Aminobutírico/metabolismo
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