Chaotic and stochastic dynamics of epileptiform-like activities in sclerotic hippocampus resected from patients with pharmacoresistant epilepsy

The types of epileptiform activity occurring in the sclerotic hippocampus with highest incidence are interictal-like events (II) and periodic ictal spiking (PIS). These activities are classified according to their event rates, but it is still unclear if these rate differences are consequences of underlying physiological mechanisms. Identifying new and more specific information related to these two activities may bring insights to a better understanding about the epileptogenic process and new diagnosis. We applied Poincaré map analysis and Recurrence Quantification Analysis (RQA) onto 35 in vitro electrophysiological signals recorded from slices of 12 hippocampal tissues surgically resected from patients with pharmacoresistant temporal lobe epilepsy. These analyzes showed that the II activity is related to chaotic dynamics, whereas the PIS activity is related to deterministic periodic dynamics. Additionally, it indicates that their different rates are consequence of different endogenous dynamics. Finally, by using two computational models we were able to simulate the transition between II and PIS activities. The RQA was applied to different periods of these simulations to compare the recurrences between artificial and real signals, showing that different ranges of regularity-chaoticity can be directly associated with the generation of PIS and II activities.     

Infection intensity-dependent accuracy of reagent strip for the diagnosis of Schistosoma haematobium and estimation of treatment prevalence thresholds

BackgroundReagent strip to detect microhematuria as a proxy for Schistosoma haematobium infections has been considered an alternative to urine filtration for individual diagnosis and community-based estimates of treatment needs for preventive chemotherapy. However, the diagnostic accuracy of reagent strip needs further investigation, particularly at low infection intensity levels.MethodsWe used existing data from a study conducted in Tanzania that employed urine filtration and reagent strip testing for S. haematobium in two villages, including a baseline and six follow-up surveys after praziquantel treatment representing a wide range of infection prevalence. We developed a Bayesian model linking individual S. haematobium egg count data based on urine filtration to reagent strip binary test results available on multiple days and estimated the relation between infection intensity and sensitivity of reagent strip. Furthermore, we simulated data from 3,000 hypothetical populations with varying mean infection intensity to infer on the relation between prevalence observed by urine filtration and the interpretation of reagent strip readings.Principal findingsReagent strip showed excellent sensitivity even for single measurement reaching 100% at around 15 eggs of S. haematobium per 10 ml of urine when traces on reagent strip were considered positive. The corresponding specificity was 97%. When traces were considered negative, the diagnostic accuracy of the reagent strip was equivalent to urine filtration data obtained on a single day. A 10% and 50% urine filtration prevalence based on a single day sampling corresponds to 11.2% and 48.6% prevalence by reagent strip, respectively, when traces were considered negative, and 17.6% and 57.7%, respectively, when traces were considered positive.Conclusions/SignificanceTrace results should be included in reagent strip readings when high sensitivity is required, but excluded when high specificity is needed. The observed prevalence of reagent strip results, when traces are considered negative, is a good proxy for prevalence estimates of S. haematobium infection by urine filtration on a single day.     

Die Cuticula der Epidermis des Regenwurms (Lumbricus terrestris L.)

Zusammenfassung Die um 3–4 dicke Cuticula des Regenwurms (Lumbricus terrestris L.) besteht aus 20–30 sich annähernd rechtwinklig kreuzenden Lagen von Cuticulafibrillen. Senkrecht zu und zwischen den sich kreuzenden Fibrillen verlaufen röhrenförmige Zellfortsätze, Cuticulakanälchen von der Oberfläche der Epithelzelle zur Epicuticula. Die Epicuticula bildet eine kontinuierliche, mit feinen, dicht stehenden Exkreszenzen besetzte Schicht. Die zelluläre, respektive extrazelluläre Natur der Cuticulastrukturen und ihr funktionelles Verhalten werden besprochen. Anmerkung bei der Korrektur. Die Herren D. Peters (Hamburg) und W. J. Schmidt (Gießen) machten uns auf die Untersuchung der Cuticulastruktur des Regenwurms durch Reed und Rudall (1948) aufmerksam.Die von den englischen Autoren gewonnenen Abdruckpräparate aus verschieden tiefen Schichten der Cuticula stimmen mit den hier gezeigten Schnittpräparaten vorzüglich überein und ergänzen sie durch die Aufsicht auf die freie Oberfläche. Mit der Abdrucktechnik sind jedoch die Cuticula-Kanälchen zwischen den Fibrillen nicht erkannt worden. Einige der Vermutungen über die Bildung der Cuticulafibrulen (s. auch Rudall 1950) dürften deshalb hinfällig geworden sein. Über die chemische Zusammensetzung der Cuticula und ihre chemischen Unterschiede gegenüber Kollagen s. Watson und Smith (1956).Mit dankenswerter Unterstützung durch das Kultusministerium des Landes Nordrhein-Westfalen durchgeführte Untersuchung.     

Organization and concerted evolution of the ampliconic Y-chromosomal TSPY genes from cattle

The Y-chromosomal gene TSPY (testis-specific protein Y-encoded) is probably involved in early spermatogenesis and has a variable copy number in different mammalian species. Analysis of bovine BAC clones leads to an estimate of 90 TSPY loci on the bovine Y chromosome. Half of these loci (TSPY-M1 and TSPY-M2) contain a single copy, while the other loci (TSPY-C) contain a cluster of three, possibly four, truncated pseudogenes. Fluorescence in situ hybridization indicated that the TSPY loci are located mainly on the short arm (Yp). The TSPY genes appear to account for about 2.5% of the Y chromosome and contain several published bovine Y-chromosomal microsatellites. The homology of TSPY and the major Y-chromosomal repetitive elements BRY.2 from cattle and OY.1 from sheep (80-85% similarity) further illustrates how the Y chromosome is shaped by rearrangements and horizontal spreading of the most abundant sequences. A comparison of TSPY-M1 sequences from different BAC clones and from related bovine species suggests concerted evolution as one of the mechanisms of the rapid evolution of the mammalian Y chromosome.     

High-resolution magnetic resonance spectroscopy of the mouse vomeronasal organ

The chemical composition of the vomeronasal organ (VNO) was investigated by means of in vitro proton magnetic resonance spectroscopy (MRS) in prepubertal and adult mice of both sexes. Results demonstrate that MRS detects several chemical constituents in the VNO, showing their age- and sex-associated changes in concentration. Preliminary experiments also suggest the ability of MRS to show compositional changes in the VNO after pheromonal stimulation. MRS can serve as a useful technique to investigate vomeronasal chemoreception.     

Free radical release in C6 glial cells enriched in hexacosanoic acid: implication for X-linked adrenoleukodystrophy pathogenesis

Free radicals have been implicated in the etiopathology of some neurological and demyelinating diseases. To evaluate their involvement in the cerebral form of X-linked adrenoleukodystrophy (cerALD) disorder, characterised by very long chain fatty acid (VLCFA) accumulation, we utilised an in vitro model using rat C6 glial cells, enriched in hexacosenoic acid (C26:0, HA). Modified cells were incubated in presence of oxidative stressors, such as bacterial endotoxin lipopolisaccharides (LPS) and human oxidised low-density lipoprotein (ox-LDL), and the production of proinflammatory cytokines, nitrite, nitrate and superoxide was determined in the supernatants. The results show that modified cells produce higher amounts of nitric oxide (NO) products and superoxide compared to native C6 cells, supporting the role of free radicals as important pathophysiological modulator of the neuroinflammatory response in ALD. This hypothesis suggests that the cerebral damage in ALD could be due to intracellular signalling activated by interaction of exogenous factors with the particular membrane fatty acid composition.