Analysis of Passive Charge Balancing for Safe Current-Mode Neural Stimulation

Charge balancing has been often considered as one of the most critical requirement for neural stimulation circuits. Over the years several solutions have been proposed to precisely balance the charge transferred to the tissue during anodic and cathodic phases. Elaborate dynamic current sources/sinks with improved matching, and feedback loops have been proposed with a penalty on circuit complexity, area or power consumption. Here we review the dominant assumptions in safe stimulation protocols, and derive mathematical models to determine the effectiveness of passive charge balancing in a typical application scenario

Cognitive deficits associated with prolonged seizures

Study aims are to assess cognitive dysfunction in nine individuals with one or more episodes of status epilepticus(SE)and to compare performance against control patients with brief seizures(idiopathic generalised epilepsy IGE, temporal lobe epilepsy TLE), and against adult performance norms. Participants with SE (30-60 minutes seizure duration) were recruited from the Cairns Base Hospital's epilepsy clinic, and included non-convulsive SE (NCSE, N=3) and generalised convulsive SE (GCSE, N=6) patients. Neuropsychological tasks assessed cognitive domains of intelligence, attention, verbal and visual memory, and executive functions. The absence SE (ASE) patient functioned normally in all cognitive domains. The patient with left complex partial status (CPSE) was significantly worse in attention; while the right CPSE patient was weakest in verbal episodic memory. GCSE patients performed worse on Sustained Attention NTS tasks than control IGE and TLE patients with brief seizures. Verbal memory was preserved. Number of SE seizures correlated negatively with estimated I.Q., visual abilities and working memory. In the absence of localised neuropsychological deficits, the deficits in stained attention and intellectual abilities of patients with GCSE suggest global cognitive dysfunction can result from relatively brief SE seizures. Generalisation of seizures cannot account for this, since the IGE performances were not affected

Cognitive deficits associated with prolonged seizures

Study aims are to assess cognitive dysfunction in nine individuals with one or more episodes of status epilepticus(SE)and to compare performance against control patients with brief seizures(idiopathic generalised epilepsy IGE, temporal lobe epilepsy TLE), and against adult performance norms. Participants with SE (30-60 minutes seizure duration) were recruited from the Cairns Base Hospital's epilepsy clinic, and included non-convulsive SE (NCSE, N=3) and generalised convulsive SE (GCSE, N=6) patients. Neuropsychological tasks assessed cognitive domains of intelligence, attention, verbal and visual memory, and executive functions. The absence SE (ASE) patient functioned normally in all cognitive domains. The patient with left complex partial status (CPSE) was significantly worse in attention; while the right CPSE patient was weakest in verbal episodic memory. GCSE patients performed worse on Sustained Attention NTS tasks than control IGE and TLE patients with brief seizures. Verbal memory was preserved. Number of SE seizures correlated negatively with estimated I.Q., visual abilities and working memory. In the absence of localised neuropsychological deficits, the deficits in stained attention and intellectual abilities of patients with GCSE suggest global cognitive dysfunction can result from relatively brief SE seizures. Generalisation of seizures cannot account for this, since the IGE performances were not affected

Variations in cognitive functioning in genetic generalized epilepsy: four case studies

Introduction. The traditional view of cognition in idiopathic or genetic generalized epilepsy (GGE) is that "one size fits all" i.e. only very mild generalized impairment might be detected, if any. This paper describes four case studies of cognitive functioning in GGE patients with photosensitivity and reflexive seizures. Aim. The aim was to discover whether each individual's set of cognitive deficits varied in accordance with his/her other clinical phenomena such as photosensitivity and kinds of reflexive seizures. Method. Neurological and cognitive performance was assessed by comprehensive evaluation of each patient based on interviews, neurologist's EEG reports and neuropsychological tests. Assessment of cognitive domains included estimated pre-morbid I.Q. based on reading ability and demographic norms, current I.Q., attention factors, verbal memory, visual memory and executive functions. Results. Clinical signs and investigative studies indicated that two cases typically began reflexive seizure episodes with facial myoclonia which evolved into tonic-clonic convulsions or generalized myoclonic seizures. These patients had widespread attention and working memory deficits, some severe, together with lowered intelligence scores. In contrast, two other cases (with no history of myoclonus) had generalized reflexive seizures originating in the occipital lobes, very mild localized visual dysfunction and high intelligence. Conclusions. The systematic variation in extent and nature of cognitive dysfunction illustrated in these cases with reflexive seizures (preceded by myoclonia or visual phenomena) would be explained by a more recent conceptualization of GGE as encompassing regional differences in variable hyperexcitability located at cortical levels or functional neural networks

Video monitoring of neovessel occlusion induced by photodynamic therapy with verteporfin (Visudyne®), in the CAM model

The aim of the present study was to monitor photodynamic angioocclusion with verteporfin in capillaries. Details of this process were recorded under a microscope in real-time using a high-sensitivity video camera. A procedure was developed based on intravenous (i.v.) injection of a light-activated drug, Visudyne®, into the chorioallantoic membrane (CAM) of a 12-day-old chicken embryo. The effect of light activation was probed after 24h by i.v. injection of a fluorescent dye (FITC dextran), and analysis of its fluorescence distribution. The angioocclusive effect was graded based on the size of the occluded vessels, and these results were compared with clinical observations. The time-resolved thrombus formation taking place in a fraction of the field of view was video recorded using a Peltier-cooled CCD camera. This vessel occlusion in the CAM model was reproducible and, in many ways, similar to that observed in the clinical use of verteporfin. The real-time video recording permitted the monitoring of platelet aggregation and revealed size-selective vascular closure as well as some degree of vasoconstriction. Platelets accumulated at intravascular junctions within seconds after verteporfin light activation, and capillaries were found to be closed 15min later at the applied conditions. Larger-diameter vessels remained patent. Repetition of these data with a much more sensitive camera revealed occlusion of the treated area after 5min with doses of verteporfin and light similar to those used clinically. Consequently, newly developed light-activated drugs can now be studied under clinically relevant condition

An Optical System to Monitor the Displacement Field of Glass-fibre Posts Subjected to Thermal Loading

Endocanalar posts are necessary to build up and retain coronal restorations but they do not reinforce dental roots. It was observed that the dislodgement of post-retained restorations commonly occurs after several years of function and long-term retention may be influenced by various factors such as temperature changes. Temperature changes, in fact, produce micrometric deformations of post and surrounding tissues/materials that may generate high stress concentrations at the interface thus leading to failure. In this study we present an optical system based on the projection moiré technique that has been utilized to monitor the displacement field of endocanalar glass-fibre posts subjected to temperature changes. Measurements were performed on forty samples and the average displacement values registered at the apical and middle region were determined for six different temperature levels. A total of 480 displacement measurements was hence performed. The values of the standard deviation computed for each of the tested temperatures over the forty samples appear reasonably small which proves the robustness and the reliability of the proposed optical technique. The possible implications for the use of the system in the applicative context were discussed

Analogies de méthodes et différences d'appareillage dans l'enregistrement d'informations corrélées

L'enregistrement des énergies de particules corrélées : expériences (α, γ), (3He, dγ), (d, pγ), (p, p' γ), expériences de polarisation [4, 6,12], a été effectué indépendamment avec des appareillages de conceptions différentes. L'un est un système d'acquisition et de contrôle utilisant une logique câblée, l'autre un ordinateur en temps réel. L'examen critique de ces appareillages et de leur utilisation conduit à des conclusions voisines

Autologous tooth graft after endodontical treated used for socket preservation: A multicenter clinical study.

The aim of the study was to evaluate the tooth extracted use as autologous tooth graft after endodontic root canal therapies used for socket preservation. To this purpose, the Tooth Transformer shredding and decontamination machine has been used. The graft obtained in this way, was inserted at the time of the extraction or at a second surgery altogether with the chosen regenerative therapy. This clinical trial enrolled patients with post-estractive defects requiring the restoration bone dimension and shape in the maxillary and mandibular zone. In addition, 98 patients with 119 extraction sockets were enrolled across 10 standardized centers. An innovative preparation method, using the dedicated automated device Tooth Transformer, able to transform autologous teeth in suitable grafting material, has been used. The extracted tooth was cleaned and treated using a Tooth Transformer and made a socket preservation. Thirteen Biopsies were realized to analyze the histologic outcomes at the average time of four months to demonstrate that the autologous tooth graft made from root after endodontic therapy should be used in human bone regeneration as graft for dental implant placement

Titanium functionalized with polylysine homopolymers: In vitro enhancement of cells growth

In oral implantology, the success and persistence of dental implants over time are guar-anteed by the bone formation around the implant fixture and by the integrity of the peri-implant mucosa seal, which adheres to the abutment and becomes a barrier that hinders bacterial penetration and colonization close to the outer parts of the implant. Research is constantly engaged in looking for substances to coat the titanium surface that guarantees the formation and persistence of the peri-implant bone, as well as the integrity of the mucous perimeter surrounding the implant crown. The present study aimed to evaluate in vitro the effects of a titanium surface coated with polylysine homopolymers on the cell growth of dental pulp stem cells and keratinocytes to establish the potential clinical application. The results reported an increase in cell growth for both cellular types cultured with polylysine-coated titanium compared to cultures without titanium and those without coating. These preliminary data suggest the usefulness of polylysine coating not only for enhancing osteoinduction but also to speed the post-surgery mucosal healings, guarantee appropriate peri-implant epithelial seals, and protect the fixture against bacterial penetration, which is responsible for compromising the implant survival

Economic impact to shipping industry : Economic impact to shipping industry considering Maritime Spatial Planning and green routes in pilot case studies

In this project, three case studies are considered in order to examine the economic impact of the implementation of MSP when considering environmental impact of the shipping industry. Specific characteristics and limitations of areas in the Greek Sea, the Balearic Sea and the Baltic Sea are evaluated with respect to their economic effects on the maritime transport domain. The purpose of the above is to evaluate the economic impacts and risk implications of different scenarios and particularly: The economic impact of vessel traffic rerouting and/or reducing the speed in order to reduce the probability of vessel strikes or other negative impact to endangered marine species. Analysis and treatment of costs (constraints and penalties) from unexpected delays, in addition to the additional transit time cost. Estimation of the direct and indirect economic impact on the shipping industry and the effects of potential port call dislocation for the implementation of the proposed management options (e.g. speed deceleration or ship rerouting).https://commons.wmu.se/monalisa2/1001/thumbnail.jp