Electrical source imaging of interictal spikes using multiple sparse volumetric priors for presurgical epileptogenic focus localization.

Electrical source imaging of interictal spikes observed in EEG recordings of patients with refractory epilepsy provides useful information to localize the epileptogenic focus during the presurgical evaluation. However, the selection of the time points or time epochs of the spikes in order to estimate the origin of the activity remains a challenge. In this study, we consider a Bayesian EEG source imaging technique for distributed sources, i.e. the multiple volumetric sparse priors (MSVP) approach. The approach allows to estimate the time courses of the intensity of the sources corresponding with a specific time epoch of the spike. Based on presurgical averaged interictal spikes in six patients who were successfully treated with surgery, we estimated the time courses of the source intensities for three different time epochs: (i) an epoch starting 50 ms before the spike peak and ending at 50% of the spike peak during the rising phase of the spike, (ii) an epoch starting 50 ms before the spike peak and ending at the spike peak and (iii) an epoch containing the full spike time period starting 50 ms before the spike peak and ending 230 ms after the spike peak. To identify the primary source of the spike activity, the source with the maximum energy from 50 ms before the spike peak till 50% of the spike peak was subsequently selected for each of the time windows. For comparison, the activity at the spike peaks and at 50% of the peaks was localized using the LORETA inversion technique and an ECD approach. Both patient-specific spherical forward models and patient-specific 5-layered finite difference models were considered to evaluate the influence of the forward model. Based on the resected zones in each of the patients, extracted from post-operative MR images, we compared the distances to the resection border of the estimated activity. Using the spherical models, the distances to the resection border for the MSVP approach and each of the different time epochs were in the same range as the LORETA and ECD techniques. We found distances smaller than 23 mm, with robust results for all the patients. For the finite difference models, we found that the distances to the resection border for the MSVP inversions of the full spike time epochs were generally smaller compared to the MSVP inversions of the time epochs before the spike peak. The results also suggest that the inversions using the finite difference models resulted in slightly smaller distances to the resection border compared to the spherical models. The results we obtained are promising because the MSVP approach allows to study the network of the estimated source-intensities and allows to characterize the spatial extent of the underlying sources.

Efecto antimicrobiano de una solución de superoxidación con pH neutro para desinfección de cavidades clase I / Effectiveness of a neutral pH super-oxidized solution for antimicrobial disinfection of class I cavities

Objetivo: determinar la disminución de la carga bacteriana en dentina de cavidades clase I posterior a la aplicación de clorhexidina 2 por ciento en comparación con la aplicación de solución de superoxidación con pH neutro. Material y métodos: Se realizó un estudio transversal clínico, a 30 pacientes en el Área de Clínicas de la Facultad de Estomatología en la Universidad Autónoma de San Luis Potosí, de los cuales se obtuvieron 60 muestras en cavidades clase I en primeros y segundos molares inferiores permanentes, previas al tratamiento y 60 posteriores que se dividieron en tres grupos, grupo control (n = 20), grupo A correspondiente a clorhexidina al 2 por ciento (n = 20) y grupo B correspondiente a solución de superoxidación con pH neutro (n = 20), posteriormente las muestras fueron llevadas al laboratorio donde se realizó una dilución seriada, para posteriormente sembrar las muestras en placas de agar soya tripticaseina y hacer el conteo de UFC después de haber sido incubadas 24 horas. Resultados: Se realizó una comparación de todos los grupos en cuanto a la disminución de carga bacteriana pretratamiento y postratamiento. Se observó diferencia es tadística significativa en el grupo tratado con clorhexidina al 2 por ciento (p < 0.01) mientras que en los grupos tratados con agua destilada y solución de superoxidación con pH neutro no fueron significativas, ambas con una (p > 0.05) entre las muestras pretratamiento y postratamiento. Conclusiones: Se logró obtener muestras en primeros y segundos molares inferiores en las que se cuantificaron microorganismos previos y posteriores al tratamiento mediante la cuantificación de UFC. Se encontraron diferencias significativas entre grupos, por lo que podemos decir de acuerdo con nuestros resultados que la clorhexidina al 2 por ciento tiene mayor efecto antimicrobiano en la desinfección de cavidades clase I que la solución de superoxidación con pH neutro.

background: Dental caries is a disease characterized by demineralization of the hard tissues of the tooth. If left untreated, it leads to cavitation, discomfort, pain, and the eventual loss of the tooth. A range of antiseptics have been used to eliminate microorganisms from cavities, one of the most common being chlorhexidine, due to the advantages it offers. Nowadays there are products available that offer not only the same microbicidal capacity, but also a greater half-life and superior tissue compatibility. One new option for cavity disinfection is pH neutral super-oxidation solution. Objective: To determine the decrease in bacterial load in the dentin of class I cavities following the application of 2% chlorhexidine compared to a neutral pH over-super-oxidized solution. Material and methods:A clinical cross-sectional study was conducted involving a total of 30 patients at the Faculty of Stomatology Clinics of the Autonomous University of San Luis Potosí, from whom 60 samples were obtained from class I cavities in first and second permanent lower molars prior to treatment and 60 following...