bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geographic and taxonomic variation inBatrachochytrium dendrobatidisinfection and transmission within a highly endemic amphibian community
Authors: Bielby J. , Bovero S. , Angelini C. , Favelli M. , Gazzaniga E. , Perkins M. , Sotgiu G. , Tessa G. , Garner T. W. J. 
Published: May 2013

AbstractAimIn a highly endemic, threatened amphibian assemblage, we measure and describe the geographic and taxonomic distribution of the amphibian chytrid fungus,Batrachochytrium dendrobatidis(Bd), with a view to identifying those sites and species most at risk of infection and its negative consequences. Additionally, we aimed to determine the potential for direct transmission events between two known carriers ofBdinfection.LocationThe island ofSardinia.MethodsWe collected swab and tissue samples of amphibians from a wide range of geographic sites and species. We used epidemiological and statistical techniques to quantify deviations from a random distribution. We used random forests to investigate habitat use and overlap in two species known to be infected byBdto quantify a surrogate measure of the contact rates between these two species.ResultsBoth geographic and taxonomic distributions ofBdwere highly non‐random: we identified a cluster of infections in the north of the island and found that two species,Euproctus platycephalusandDiscoglossus sardus, had a relatively high prevalence of infection within this cluster. Our analyses suggest that, on the basis of their fine‐scale habitat use, they have relatively little opportunity for direct transmission and could maintainBdinfection independently.Main conclusionsOur results illustrate how obtaining detailed information on the geographic and taxonomic distribution of infection is a useful first step in assessing the risk of infection for species within the region. Attempting to quantify possible routes of transmission amongst species further aids us in identifying mechanisms of pathogen persistence within the host community. Within this assemblage, we have identified two hosts that carry infection and may be at risk. Further, our research suggests that these two species may be able to maintain infection independently of one another, which has implications for attempts to mitigate this parasite.
Conservation implications of divergent global patterns of ant and vertebrate diversity
Authors: Jenkins Clinton N. , Guénard Benoit , Diamond Sarah E. , Weiser Michael D. , Dunn Robert R. 
Published: May 2013

AbstractAimGlobal conservation planning is often oriented around vertebrates and plants, yet most organisms are invertebrates. To explore the potential conservation implications of this bias, we assessed how well patterns of diversity for an influential group of invertebrates, the ants, correspond with those of three vertebrate groups (birds, mammals and amphibians).LocationGlobal.MethodsWe compiled data on the number of genera of ants and the three vertebrate groups for 370 political regions across the world. We then compared their correlations both for overall diversity and between subsets of genera likely to be of conservation concern. We also developed generalized additive models (GAM) to identify regions where vertebrates and ants diverged in their diversity patterns.ResultsWhile ant and vertebrate diversity do positively correlate, the correlations are substantially weaker for the ant lineages of the greatest conservation concern. Vertebrates also notably fail to predict ant diversity in specific geographic areas, including Australia and Southeast Asia, parts of Africa and Madagascar, and south‐western China. These failures may be genuine differences in diversity patterns, or they may indicate important gaps in our knowledge of ant and vertebrate diversity.Main conclusionsWe conclude that it is currently unwise to assume that global conservation priorities based on vertebrates will conserve ants as well. We suspect that this also applies to other invertebrates.
The puzzle(s) of pharmacoresistant epilepsy
Authors: Pohlmann‐Eden Bernd , Weaver Donald F. 
Published: May 2013

SummaryDespite the availability of >25 antiepileptic drugs, 30% of people with epilepsy do not respond to conventional agents, exhibiting pharmacoresistance (PR)—a high percentage that has not changed significantly in decades. This is not surprising given that all current pharmaceutical agents merely reduce the incidence of seizures (“antiictogenic”); they do not interfere with the natural history of epilepsy and are therefore not antiepileptogenic. The two prevailing hypotheses of pharmacoresistance, the target hypothesis and the transporter hypothesis, can only partially explain the complexity and the diversity of PR. It is a neuropharmacologic priority that we change our approach to understanding PR. Herein we suggest the need to regard PR as a complex puzzle in which the target and transporter hypotheses represent a very small piece of the whole. Indeed, we do not even know if this piece of the whole is epiphenomenal or neurobiologically causal. To grasp the whole, we need to constantly gather information (look around for other pieces) from other perspectives and insights coming from clinical, epidemiologic, neuroradiologic, genetic, and other data. A recent research workshop on PR, the 2nd Halifax International Epilepsy Conference & Retreat, chose this eclectic and all‐encompassing approach. The participants were fully aware that their diverse contributions represent only still‐fragmented pieces of this frustrating but clinically important puzzle.
Road to refractory epilepsy: The Glasgow story
Authors: Brodie Martin J. 
Published: May 2013

SummaryThis short article reviews 30 years of prospective observations on outcomes relevant to an expanding cohort of adolescent and adult patients with newly diagnosed epilepsy, who received their first antiepileptic drug (AED) and subsequent long‐term follow‐up at the Epilepsy Unit at the Western Infirmary in Glasgow, United Kingdom. Despite the fact that the overall prognosis has slowly improved over this time, >30% of the patients remain uncontrolled despite the introduction of a range of new AEDs, some with unique mechanisms of action, over the last 20 years. Most patients followed a constant course (59% controlled, 25% refractory), which could usually be predicted early. The remaining 16% fluctuated between periods of remission and relapse. The likelihood of seizure freedom declined with successive drug regimens, most markedly from the first to the third. A number of factors predicting poorer outcomes have been identified, particularly high pretreatment seizure density and concomitant psychiatric comorbidities. Novel approaches to identifying and treating the processes underpinning the generation and propagation of seizures are required if the current rather disappointing scenario is to be substantially improved.
The enigma of placebo effects in drug‐refractory epilepsies
Authors: Krämer Günter 
Published: May 2013

SummaryPlacebo effects in the therapy of epilepsy were already known before the introduction of effective antiepileptic drugs (AEDs). They have physiologic correlates, and are even stronger in other neurologic disorders such as pain. Placebo effects in epilepsy have many facets. Our understanding of this phenomenon has increased in the last two decades: placebo effects are stronger in children than in adults, and may be culture‐ and setting‐dependent; and impressive placebo effects occur in animals with epilepsy as well. More research is needed to fully elucidate the mechanism of placebo effects in epilepsy care, particularly as we go forth with studies addressing the issue of pharmacoresistance.
The intrinsic severity hypothesis of pharmacoresistance to antiepileptic drugs
Authors: Rogawski Michael A. 
Published: May 2013

SummaryPharmacoresistance to antiepileptic drugs (AEDs) is a barrier to seizure freedom for many persons with epilepsy. For nearly two decades, pharmacoresistance has been framed in terms of factors affecting the access of AEDs to their molecular targets in the brain or the actions of the drugs on these targets. Shortcomings in this prevailing view led to the formulation of the intrinsic severity hypothesis of pharmacoresistance to AEDs, which is based on the recognition that there are neurobiologic factors that confer phenotypic variation among individuals with etiologically similar forms of epilepsy and postulates that more severe epilepsy is more difficult to treat with AEDs. In recent years, progress has been made identifying potential genetic mechanisms of variation in epilepsy severity, including subclinical mutations in ion channels that increase or reduce epilepsy severity in mice. Efforts are underway to identify clinically important genetic modifiers. If it can be demonstrated that such severity factors play a role in pharmacoresistance, treatments could be devised to reverse severity mechanisms. By overcoming pharmacoresistance, this new approach to epilepsy therapy may allow drug refractory patients to achieve seizure freedom without side effects.
The methylation hypothesis of pharmacoresistance in epilepsy
Authors: Kobow Katja , El‐Osta Assam , Blümcke Ingmar 
Published: May 2013

SummarySeizures cannot be medically controlled in approximately 40% of people with epilepsy. Although we are beginning to understand how to better treat certain seizure types, we still do not know the regulatory events that determine antiepileptic drug resistance. Proposed pathoetiologic mechanisms include altered expression of drug targets (i.e., receptor or ion channel modifications), endothelial drug transporter activation (i.e., increasing drug clearance), or intrinsic severity factors. The latter hypothesis results from an often confirmed clinical observation, that seizure severity is a reliable predictor for the development of pharmacoresistance (PR) in epilepsy. Herein, we propose, that genome modifications that do not involve changes to the DNA sequence per se (i.e., epigenetic changes) could confer PR in patients with epilepsy. Seizures cause excessive neuronal membrane depolarization, which can influence the cellular nucleus; we thus hypothesize that seizures can mediate epigenetic modifications that result in persistent genomic methylation, histone density, and posttranslational modifications, as well as noncoding RNA‐based changes. Although experimental evidence is lacking in epilepsy, such mechanisms are well characterized in cancer, either as a result of anticancer drugs themselves or cancer‐related intrinsic signals (i.e., noncoding RNAs). We suggest that similar mechanisms also play a role in PR epilepsies. Addressing such epigenetic mechanisms may be a successful strategy to increase the brain's sensitivity to antiepileptic drugs and may even act as disease‐modifying treatment.
Is routine electroencephalography (EEG) a useful biomarker for pharmacoresistant epilepsy?
Authors: Steinhoff Bernhard J. , Scholly Julia , Dentel Christel , Staack Anke Maren 
Published: May 2013

SummaryPeople with seizure disorders who have been treated at the Kork Epilepsy Center over a prolonged time period and who thus provide data concerning the chronic course of epilepsy were investigated in order to address the potential role of electroencephalography (EEG) as a biomarker for pharmacoresistant epilepsy. Clinical course and the corresponding findings from their first recorded EEG, their first EEG following appropriate treatment, and their last EEG were compared. Furthermore, we investigated if interictal epileptiform discharges (IEDs) differ in amplitude and morphology if recorded in long‐term seizure‐free patients. The early cessation of IEDs was a relatively good marker for a good prognosis, especially in idiopathic generalized epilepsies. However, persistent IEDs had no major impact on the long‐term prognosis. We found no differences between IEDs in seizure‐free patients or patients with ongoing seizures. Therefore, in our hands, routine EEG was not an appropriate biomarker for the prediction of pharmacoresistant epilepsy. Additional factors such as etiology and pathophysiology also need to be considered.
Can we develop pathology‐specific MRI contrast for “MR‐negative” epilepsy?
Authors: Feindel Kirk W. 
Published: May 2013

SummaryRecent improvements in magnetic resonance imaging (MRI) hardware, software, and analysis routines are helping to put cases of “MR‐negative” epilepsy on the decline. However, most standard‐of‐care MRI relies on careful manipulation and presentation of T1, T2, and diffusion‐weighted contrast, which characterize the behavior of water in “bulk” tissue rather than providing pathology‐specific contrast. Research efforts in MR physics continue to identify and develop novel theory, and methods such as diffusional kurtosis imaging (DKI) and temporal diffusion spectroscopy that can better characterize tissue substructure, and chemical exchange saturation transfer (CEST) that can target underlying biochemical processes. The potential role of each technique in targeting pathologies implicated in “MR‐negative” epilepsy is outlined herein.
A conceptual framework for the use of neuroimaging to study and predict pharmacoresistance in epilepsy
Authors: Pohlmann‐Eden Bernd , Crocker Candice E. , Schmidt Matthias H. 
Published: May 2013

SummaryTwenty percent to 49% of newly treated patients with epilepsy will develop pharmacoresistance (PR). The mechanisms leading to PR are unclear. There is currently no unifying theory to explain the variety of presentations of PR and the diversity of potential contributing factors. Etiology of seizures seems to play a critical role in at least a subset of PR. Many magnetic resonance imaging (MRI) studies in the advanced stages of epilepsy suggest a strong association between lesions such as hippocampal sclerosis and focal cortical dysplasia and PR. Unfortunately, almost all of these studies are cross‐sectional and retrospective. There is a need for a new perspective on the role of preexisting lesions in the evolution of epilepsy and PR. We propose in this article to study a unique population of drug‐naive patients with either first seizure or new‐onset epilepsy longitudinally with advanced MRI imaging techniques, including magnetic resonance spectroscopy and diffusion tensor imaging. We hope to be able to monitor imaging findings and the development of PR early in the course of the disease in a subset of these patients with temporal lobe epilepsy (TLE). Our goal is to understand the pathogenesis of PR, to dissect changes associated with the development of PR from changes associated with chronic seizures and medication, and ultimately to predict PR at the onset of disease.
Pharmacoresistant epilepsy: Unmet needs in solving the puzzle(s)
Authors: Weaver Donald F. , Pohlmann‐Eden Bernd 
Published: May 2013

SummaryPharmacoresistant epilepsy is a significant medical problem. The 2nd Halifax International Epilepsy Conference & Retreat identified crucial needs, which if successfully addressed, will aid in paving the way to improved lives for people with pharmacoresistant epilepsy. These are needs: (1) for an evidence‐based and dynamic definition of pharmacoresistant epilepsy; (2) for a comprehensive description of the natural history of pharmacoresistant epilepsy; (3) for a comprehensive description of the complications and comorbidities of pharmacoresistant epilepsy; (4) for a rigorous delineation of the epidemiology and socioeconomic impact of pharmacoresistant epilepsy; (5) for clinically meaningful diagnostic and prognostic physiologically based electroencephalography (EEG) biomarkers; (6) for clinically meaningful diagnostic and prognostic anatomically based (MRI Imaging) biomarkers; (7) for biomolecular/biochemical mechanistic understanding of etiopathogenesis for pharmacoresistant epilepsy; (8) for representative animal models of pharmacoresistant epilepsy; (9) for new and effective drugs or other novel treatments for pharmacoresistant epilepsy; and (10) to promote continuing research and research funding targeting pharmacoresistant epilepsy.
Potential for unreliable interpretation of EEG recorded with microelectrodes
Authors: Stacey William C. , Kellis Spencer , Greger Bradley , Butson Christopher R. , Patel Paras R. , Assaf Trevor , Mihaylova Temenuzhka , Glynn Simon 
Published: May 2013

SummaryPurposeRecent studies in epilepsy, cognition, and brain machine interfaces have shown the utility of recording intracranial electroencephalography (iEEG) with greater spatial resolution. Many of these studies utilize microelectrodes connected to specialized amplifiers that are optimized for such recordings. We recently measured the impedances of several commercial microelectrodes and demonstrated that they will distort iEEG signals if connected to clinical EEG amplifiers commonly used in most centers. In this study we demonstrate the clinical implications of this effect and identify some of the potential difficulties in using microelectrodes.MethodsHuman iEEG data were digitally filtered to simulate the signal recorded by a hybrid grid (two macroelectrodes and eight microelectrodes) connected to a standard EEG amplifier. The filtered iEEG data were read by three trained epileptologists, and high frequency oscillations (HFOs) were detected with a well‐known algorithm. The filtering method was verified experimentally by recording an injected EEG signal in a saline bath with the same physical acquisition system used to generate the model. Several electrodes underwent scanning electron microscopy (SEM).Key FindingsMacroelectrode recordings were unaltered compared to the source iEEG signal, but microelectrodes attenuated low frequencies. The attenuated signals were difficult to interpret: all three clinicians changed their clinical scoring of slowing and seizures when presented with the same data recorded on different sized electrodes. The HFO detection algorithm was oversensitive with microelectrodes, classifying many more HFOs than when the same data were recorded with macroelectrodes. In addition, during experimental recordings the microelectrodes produced much greater noise as well as large baseline fluctuations, creating sharply contoured transients, and superimposed “false” HFOs. SEM of these microelectrodes demonstrated marked variability in exposed electrode surface area, lead fractures, and sharp edges.SignificanceMicroelectrodes should not be used with low impedance (<1 GΩ) amplifiers due to severe signal attenuation and variability that changes clinical interpretations. The current method of preparing microelectrodes can leave sharp edges and nonuniform amounts of exposed wire. Even when recorded with higher impedance amplifiers, microelectrode data are highly prone to artifacts that are difficult to interpret. Great care must be taken when analyzing iEEG from high impedance microelectrodes.
Ictal‐onset localization through connectivity analysis of intracranial EEG signals in patients with refractory epilepsy
Authors: van Mierlo Pieter , Carrette Evelien , Hallez Hans , Raedt Robrecht , Meurs Alfred , Vandenberghe Stefaan , Van Roost Dirk , Boon Paul , Staelens Steven , Vonck Kristl 
Published: May 2013

SummaryPurposeFifteen percent to 25% of patients with refractory epilepsy require invasive video–electroencephalography (EEG) monitoring (IVEM) to precisely delineate the ictal‐onset zone. This delineation based on the recorded intracranial EEG (iEEG) signals occurs visually by the epileptologist and is therefore prone to human mistakes. The purpose of this study is to investigate whether effective connectivity analysis of intracranially recorded EEG during seizures provides an objective method to localize the ictal‐onset zone.MethodsIn this study data were analyzed from eight patients who underwent IVEM at Ghent University Hospital in Belgium. All patients had a focal ictal onset and were seizure‐free following resective surgery. The effective connectivity pattern was calculated during the first 20 s of ictal rhythmic iEEG activity. The out‐degree, which is reflective of the number of outgoing connections, was calculated for each electrode contact for every single seizure during these 20 s. The seizure specific out‐degrees were summed per patient to obtain the total out‐degree. The electrode contact with the highest total out‐degree was considered indicative of localization of the ictal‐onset zone. This result was compared to the conclusion of the visual analysis of the epileptologist and the resected brain region segmented from postoperative magnetic resonance imaging (MRI).Key findingsIn all eight patients the electrode contact with the highest total out‐degree was among the contacts identified by the epileptologist as the ictal onset. This contact, that we named “the driver,” always laid within the resected brain region. Furthermore, the patient‐specific connectivity patterns were consistent over the majority of seizures.SignificanceIn this study we demonstrated the feasibility of correctly localizing the ictal‐onset zone from iEEG recordings by using effective connectivity analysis during the first 20 s of ictal rhythmic iEEG activity.
Feeding strategy of the non‐native rainbow trout,Oncorhynchus mykiss, in low‐orderPatagonian streams
Authors: Di Prinzio C. Y. , Miserendino M. L. , Casaux R. 
Published: May 2013

AbstractThe dietary composition and feeding strategy of rainbow trout,Oncorhynchus mykiss(Walbaum), in two low‐order Patagonian streams were studied. Benthic macroinvertebrate availability was estimated in both riffles and pools. Fish stomach contents were examined to determine prey richness and diversity, prey electivity, food‐niche width, and the feeding strategy employed by trout throughout the year. Availability of benthos varied seasonally with Ephemeroptera, Trichoptera, Plecoptera and Diptera species dominating. Rainbow trout diet was composed mainly of benthic macroinvertebrates, followed by terrestrial insects, fish, algae and plants. Different trout size classes segregated the use of food resources to reduce predation pressure. Elected prey included organisms displaying no to high mobility. A high feeding plasticity allows trout to buffer changes in food availability by switching from a specialised to a generalised feeding behaviour. Consequently, trout may exploit abundant but temporary food resources opportunistically, which would explain their marked expansion in Patagonian environments.
Effect of Water Content of Synthetic Hydrogel on Dehydration Performance of Nanoporous LTA Zeolite Membranes
Authors: Shirazian Saeed , Ghafarnejad Parto Soheila , Ashrafizadeh Seyed Nezameddin 
Published: May 2013

Nanoporous LTA‐type zeolite membranes were synthesized on α‐Al2O3 disk as substrate using secondary growth method. A gel formula of 1 Al2O3: 2 SiO2: 3.4 Na2O: W H2O in molar basis was chosen while its water content (W) was varied. Four levels of water contents of 140, 155, 175, and 200 were selected for membrane synthesis. The results showed that the best membrane was synthesized with water content of 155. The most efficient zeolite membrane showed a permeation flux of 0.5 kg/m2/h and a separation factor of 3800 in dehydration of a 5/95 (wt%) water/isopropanol mixture at 298 K.
Description of the novel HLA‐DPB1*137:01 allele found in an Italian subject
Authors: Cosentini E. , Frison S. , Longhi E. , Luongo V. , Ciardiello G. , Bruno P. , Mantovani M. 
Published: May 2013

SummaryIn this report, we describe the identification and sequencing of a novel HLA‐DPB1 allele, found in an Italian haematological patient. This allele is identical to DPB1*17:01 except for a single nucleotide substitution (GAC→GAG) at position 57, which changes the encoded amino acid from Asp to Glu.