Consciousness transitions during epilepsy seizures through the lens of integrated information theory.

Consciousness is one of the most complex aspects of human experience. Studying the mechanisms involved in the transitions among different levels of consciousness remains as one of the greatest challenges in neuroscience. In this study we use a measure of integrated information (ΦAR) to evaluate dynamic changes during consciousness transitions. We applied the measure to intracranial electroencephalography (SEEG) recordings collected from 6 patients that suffer from refractory epilepsy, taking into account inter-ictal, pre-ictal and ictal periods. We analyzed the dynamical evolution of ΦAR in groups of electrode contacts outside the epileptogenic region and compared it with the Consciousness Seizure Scale (CCS). We show that changes on ΦAR are significantly correlated with changes in the reported states of consciousness.

Comparison of the Two Types of Stimulating Electrodes in the Study of Motor Nerve Conduction in Dogs.

In this research two kinds of stimulation electrodes were compared in motor nerve conduction study: needle electrodes used in human medicine and electrodes made of injection needles connected to the stimulator via alligator-type electrodes. A study was conducted in 22 mixed-breed dogs. The resulting values of the potential amplitudes of the stimulus, the parameters of the complex muscle potentials, and the motor nerve conduction velocity were statistically compared. There was no statistical difference between the parameters obtained with the two types of stimulation electrodes. The results of our research constitute a basis for improving present-day procedures, improving aseptic procedures, reducing tissue trauma during research and lowering research costs due to the introduction of injection-needle electrodes and their benefits into the study of motor nerve conduction in animals.

Toward noninvasive monitoring of ongoing electrical activity of human uterus and fetal heart and brain.

OBJECTIVE: To evaluate whether a full-coverage fetal-maternal scanner can noninvasively monitor ongoing electrophysiological activity of maternal and fetal organs. METHODS: A simulation study was carried out for a scanner with an array of magnetic field sensors placed all around the torso from the chest to the hip within a horizontal magnetic shielding enclosure. The magnetic fields from internal organs and an external noise source were computed for a pregnant woman with a 35-week old fetus. Signal processing methods were used to reject the external and internal interferences, to visualize uterine activity, and to detect activity of fetal heart and brain. RESULTS: External interference was reduced by a factor of 1000, sufficient for detecting signals from internal organs when combined with passive and active shielding. The scanner rejects internal interferences better than partial-coverage arrays. It can be used to estimate currents around the uterus. It clearly detects spontaneous activity from the fetal heart and brain without averaging and weaker evoked brain activity at all fetal head positions after averaging. CONCLUSION: The simulated device will be able to monitor the ongoing activity of the fetal and maternal organs. SIGNIFICANCE: This type of scanner may become a novel tool in fetal medicine.

Forward and inverse effects of the complete electrode model in neonatal EEG.

This paper investigates finite element method-based modeling in the context of neonatal electroencephalography (EEG). In particular, the focus lies on electrode boundary conditions. We compare the complete electrode model (CEM) with the point electrode model (PEM), which is the current standard in EEG. In the CEM, the voltage experienced by an electrode is modeled more realistically as the integral average of the potential distribution over its contact surface, whereas the PEM relies on a point value. Consequently, the CEM takes into account the subelectrode shunting currents, which are absent in the PEM. In this study, we aim to find out how the electrode voltage predicted by these two models differ, if standard size electrodes are attached to a head of a neonate. Additionally, we study voltages and voltage variation on electrode surfaces with two source locations: 1) next to the C6 electrode and 2) directly under the Fz electrode and the frontal fontanel. A realistic model of a neonatal head, including a skull with fontanels and sutures, is used. Based on the results, the forward simulation differences between CEM and PEM are in general small, but significant outliers can occur in the vicinity of the electrodes. The CEM can be considered as an integral part of the outer head model. The outcome of this study helps understanding volume conduction of neonatal EEG, since it enlightens the role of advanced skull and electrode modeling in forward and inverse computations.NEW & NOTEWORTHY The effect of the complete electrode model on electroencephalography forward and inverse computations is explored. A realistic neonatal head model, including a skull structure with fontanels and sutures, is used. The electrode and skull modeling differences are analyzed and compared with each other. The results suggest that the complete electrode model can be considered as an integral part of the outer head model. To achieve optimal source localization results, accurate electrode modeling might be necessary.

The influence of sulcus width on simulated electric fields induced by transcranial magnetic stimulation.

Volume conduction models can help in acquiring knowledge about the distribution of the electric field induced by transcranial magnetic stimulation. One aspect of a detailed model is an accurate description of the cortical surface geometry. Since its estimation is difficult, it is important to know how accurate the geometry has to be represented. Previous studies only looked at the differences caused by neglecting the complete boundary between cerebrospinal fluid (CSF) and grey matter (Thielscher et al 2011 NeuroImage 54 234-43, Bijsterbosch et al 2012 Med. Biol. Eng. Comput. 50 671-81), or by resizing the whole brain (Wagner et al 2008 Exp. Brain Res. 186 539-50). However, due to the high conductive properties of the CSF, it can be expected that alterations in sulcus width can already have a significant effect on the distribution of the electric field. To answer this question, the sulcus width of a highly realistic head model, based on T1-, T2- and diffusion-weighted magnetic resonance images, was altered systematically. This study shows that alterations in the sulcus width do not cause large differences in the majority of the electric field values. However, considerable overestimation of sulcus width produces an overestimation of the calculated field strength, also at locations distant from the target location.

Impact of pesticide contamination on aquatic microorganism populations in the littoral zone.

The effect of pesticide contamination of the littoral zone on the population of bacteria and fungi was analyzed using the example of a eutrophic water reservoir exposed for >30 years to the influence of expired crop-protection chemicals, mainly DDT. For three consecutive years, quantity analyses of bacteria and fungi were conducted and the composition of the microorganism population analyzed against seasonal dynamics. Mold and yeast-like fungi were also isolated and identified. Within the Bacteria domain, in addition to the large groups of microorganisms (Alphaprotobacteria, Betaprobacteria, and Gammaproteobacteria, Actinobacteria, and Cytophaga-Flavobacterium), the analysis also involved the presence of bacteria predisposed to degraded pesticides in natural environments: Pseudomonas spp. and Alcaligenes spp. The quantity dynamics of aquatic microorganisms indicated that bacteria and fungi under the influence of long-term exposure to DDT can adapt to the presence of this pesticide in water. No modifying effect of DDT was observed on the quantity of microorganisms or the pattern of seasonal relationships in the eutrophic lake. Changes were shown in the percentage share of large groups of bacteria in the community of microorganisms as was an effect of contamination on the species diversity of fungi. The data show the effectiveness of aquatic microorganism-community analyses as a tool for indicating changes in the water environment caused by pesticide contamination.

Monocytic ehrlichiosis in dogs.

Ehrlichiosis is the multiorgan infectious disease caused by small, intracellular rickettsias from the genus Ehrlichia. These microorganisms are known as an etiologic factor of infections world wide in humans and in different species of animals. Dog ehrlichiosis can be caused by several species of Ehrlichia attacking different groups of blood cells, but most often an infection by Ehrlichia canis is diagnosed with special relation to monocytes. A vector for E. canis are Rhipicephalus sanguineus and Ixodes ricinus, commonly occurring in Poland. Disease caused by E. canis is known as Canine Monocytic Ehrlichiosis (CME). The disease most often has an asymptomatic course which can, in favourable circumstances, run into acute or chronic forms. The acute form of CME proceeds usually with fever, apathy, weakness and accompanying respiratory symptoms, lameness and disturbances in blood coagulation. In laboratory examinations thrombocytopenia, anemia and leucopenia are ascertained. The chronic form of CME proceeds among gentle, unspecific symptoms which may last even 5 years. The CME diagnosis is difficult and often demands parallel different diagnostic methods. A medicines of choice in the ehrlichiosis treatment are antibiotics from the group of tetracyclines, given at least for 28 days. They are largely efficient during treatment of the acute CME, causing the quick improvement. Instead, in the case of chronic form, answer for treatment can be weak, and cases of resistance to antibiotics ave known.

A clinical evaluation of glass-fibre posts and restorative materials used for the reconstruction of fractured canines after one-step root canal treatment in cats.

This article describes a procedure for a one-step root canal treatment and the subsequent restoration of fractured canine teeth in cats. Standard glass fibre posts were used in the reconstruction of the teeth which were then divided into two groups and restored anatomically using two different composite materials. The procedures were successfully performed on six cats. The subject teeth were four upper and two lower canines.

The clinical significance of class III (suspicious) urine cytology.

BACKGROUND: Urine cytology, combined with cystoscopy, is the mainstay of the diagnosis and surveillance of urothelial carcinoma (UC). While classes I and II urine cytology are considered benign and classes IV and V are considered malignant the clinical significance of class III urine cytology is unclear. We evaluated the positive predictive value of class III urine cytology for concurrent and subsequent UC. METHODS: The records of all class III urine cytology cases during a 3-year period were retrospectively reviewed for the presence of concurrent and subsequent UC, determined by cystoscopy and histological confirmation. RESULTS: Of 111 cases, 54 (48.7%) were associated with concurrent UC and 14 (12.6%) with subsequent UC after an initial evaluation negative for malignancy, with a mean time to diagnosis of 10.8 months. Of 27 cases of class III urine cytology with no prior history of UC, 13 (48.1%) had concomitant UC and none had subsequent UC. Of 84 cases of class III urine cytology with a prior history of UC, 41 (48.8%) had a concomitant diagnosis of UC and 14 (16.7%) developed UC during their follow-up, leading to a total of 55 (65.5%) cases of UC. CONCLUSIONS: Patients with class III urine cytology and a prior history of UC should undergo a full initial evaluation of their urinary tract, and should be followed vigorously if this evaluation is negative for malignancy. Patients without a prior diagnosis of UC and class III urine cytology should also undergo a full initial evaluation, while further larger studies are needed to elucidate the need for further follow-up in such patients.

Characterization of border structure using fractal dimension in melanomas.

There are many characteristics that differentiate normal moles (nevi) from melanomas. One of them is their boundary irregularity, which can be quantified using Fractal Dimension. In this work, fractal dimension of normal moles and melanoma was computed using the box counting method. These measurements were used to train a linear decoder in order to predict the pathology. The average performance to discriminate normal moles from melanomas reached 85% giving some insights about the power of the fractal dimension as a candidate for automatic detection and diagnosis.

A wavelet approach for on-line spike sorting in tetrode recordings.

A new method for spike sorting of tetrode recordings during data acquisition is introduced. For each tetrode channel, putative spikes are detected by means of a threshold, and then convolved with a cascade of wavelet filters. These transformed putative spikes are averaged and this average is used as a matched filter to find portions of signals that are likely to contain a spike. A collection of vectors containing the correlation coefficients between putative spikes and the matched filters is then clustered using K-Means. Centroids of the resulting clusters contain enough information to sort spikes recorded by all tetrode channels simultaneously. On-line sorting is achieved by measuring euclidean distance between putative new spikes and the cluster centroids.

Selected fluorescent techniques for identification of the physiological state of individual water and soil bacterial cells - review.

Stimulated by demands of the natural environment conservation, the need for thorough structural and functional identification of microorganisms colonizing different ecosystems has contributed to an intensive advance in research techniques. The article shows that some of these techniques are also a convenient tool for determination of the physiological state of single cells in a community of microorganisms. The paper presents selected fluorescent techniques, which are used in research on soil, water and sediment microorganisms. It covers the usability of determination of the dehydrogenase activity of an individual bacterial cell (CTC+) and of bacteria with intact, functioning cytoplasmic membranes, bacteria with an integrated nucleiod (NuCC+) as well as fluorescent in situ hybridization (FISH).

Subject-specific, multiscale simulation of electrophysiology: a software pipeline for image-based models and application examples.

Many simulation studies in biomedicine are based on a similar sequence of processing steps, starting from images and running through geometric model generation, assignment of tissue properties, numerical simulation and visualization of the results--a process known as image-based geometric modelling and simulation. We present an overview of software systems for implementing such a sequence both within highly integrated problem-solving environments and in the form of loosely integrated pipelines. Loose integration in this case indicates that individual programs function largely independently but communicate through files of a common format and support simple scripting, so as to automate multiple executions wherever possible. We then describe three specific applications of such pipelines to translational biomedical research in electrophysiology.

Amphotericin B removal by plasma exchange.

This case report adds pharmacokinetic knowledge regarding amphotericin B. Amphotericin B is highly protein bound. Plasma exchange removes 50-75% of a substance in plasma within 1-2 h, corresponding to an elimination half-life of 30-40 min. Amphotericin B reduction ratio by plasma exchange was 40% in this patient who had both liver and renal failure.

Accuracy and run-time comparison for different potential approaches and iterative solvers in finite element method based EEG source analysis.

Accuracy and run-time play an important role in medical diagnostics and research as well as in the field of neuroscience. In Electroencephalography (EEG) source reconstruction, a current distribution in the human brain is reconstructed noninvasively from measured potentials at the head surface (the EEG inverse problem). Numerical modeling techniques are used to simulate head surface potentials for dipolar current sources in the human cortex, the so-called EEG forward problem.In this paper, the efficiency of algebraic multigrid (AMG), incomplete Cholesky (IC) and Jacobi preconditioners for the conjugate gradient (CG) method are compared for iteratively solving the finite element (FE) method based EEG forward problem. The interplay of the three solvers with a full subtraction approach and two direct potential approaches, the Venant and the partial integration method for the treatment of the dipole singularity is examined. The examination is performed in a four-compartment sphere model with anisotropic skull layer, where quasi-analytical solutions allow for an exact quantification of computational speed versus numerical error. Specifically-tuned constrained Delaunay tetrahedralization (CDT) FE meshes lead to high accuracies for both the full subtraction and the direct potential approaches. Best accuracies are achieved by the full subtraction approach if the homogeneity condition is fulfilled. It is shown that the AMG-CG achieves an order of magnitude higher computational speed than the CG with the standard preconditioners with an increasing gain factor when decreasing mesh size. Our results should broaden the application of accurate and fast high-resolution FE volume conductor modeling in source analysis routine.