Echolocation calls of the bats of Trinidad, West Indies: is guild membership reflected in echolocation signal design?

Time-expanded echolocation calls were recorded from 29 species of Neotropical bats in lowland moist tropical forest in Trinidad, West Indies with three aims (I) to describe the echolocation calls of the members of a diverse Neotropical bat community, especially members of the family Phyllostomidae, whose calls are not well documented (2) to investigate whether multivariate analysis of calls allows species and foraging guilds to be identified and (3) to evaluate the use of bat detectors in surveying the phyllostomids of Neotropical forests. The calls of 12 species of the family Phyllostomidae are described here for the first time and a total of 29 species, belonging to five families (Emballonuridae, Mormoopidae, Phyllostomidae, Molossidae and Vespertilionidae) were recorded Quadratic discriminant function analysis (DFA) was used to obtain classification rates for each one of 11 individual species and for six guilds (based on diet, foraging mode and habitat) comprising 26 species Overall classification rates were low compared to similar studies conducted in the Palaeotropics We suggest that this may be due to a combination of ecological plasticity for certain species and a loose relationship between echolocation call shape, fine-grained resource partitioning and resource acquisition in phyllostomids

Adaptive filtering methods for identifying cross-frequency couplings in human EEG.

Oscillations have been increasingly recognized as a core property of neural responses that contribute to spontaneous, induced, and evoked activities within and between individual neurons and neural ensembles. They are considered as a prominent mechanism for information processing within and communication between brain areas. More recently, it has been proposed that interactions between periodic components at different frequencies, known as cross-frequency couplings, may support the integration of neuronal oscillations at different temporal and spatial scales. The present study details methods based on an adaptive frequency tracking approach that improve the quantification and statistical analysis of oscillatory components and cross-frequency couplings. This approach allows for time-varying instantaneous frequency, which is particularly important when measuring phase interactions between components. We compared this adaptive approach to traditional band-pass filters in their measurement of phase-amplitude and phase-phase cross-frequency couplings. Evaluations were performed with synthetic signals and EEG data recorded from healthy humans performing an illusory contour discrimination task. First, the synthetic signals in conjunction with Monte Carlo simulations highlighted two desirable features of the proposed algorithm vs. classical filter-bank approaches: resilience to broad-band noise and oscillatory interference. Second, the analyses with real EEG signals revealed statistically more robust effects (i.e. improved sensitivity) when using an adaptive frequency tracking framework, particularly when identifying phase-amplitude couplings. This was further confirmed after generating surrogate signals from the real EEG data. Adaptive frequency tracking appears to improve the measurements of cross-frequency couplings through precise extraction of neuronal oscillations.

Messenger RNA expression of transporter and ion channel genes in undifferentiated and differentiated Caco-2 cells compared to human intestines.

PURPOSE: The purpose of this work was to study the influence of cell differentiation on the mRNA expression of transporters and channels in Caco-2 cells and to assess Caco-2 cells as a model for carrier-mediated drug transport in the intestines. METHOD: Gene mRNA expression was measured using a custom-designed microarray chip with 750 deoxyoligonucleotide probes (70mers). Each oligomer was printed four times on poly-lysine-coated glass slides. Expression profiles were expressed as ratio values between fluorescence intensities of Cy3 and Cy5 dye-labeled cDNA derived from poly(A) + RNA samples of Caco-2 cells and total RNA of human intestines. RESULTS: Significant differences in the mRNA expression profile of transporters and channels were observed upon differentiation of Caco-2 cells from 5 days to 2 weeks in culture, including changes for MAT8, S-protein, and Nramp2. Comparing Caco-2 cells of different passage number revealed few changes in mRNAs except for GLUT3, which was down-regulated 2.4-fold within 13 passage numbers. Caco-2 cells had a similar expression profile when either cultured in flasks or on filters but differed more strongly from human small and large intestine, regardless of the differentiation state of Caco-2 cells. Expression of several genes highly transcribed in small or large intestines differed fourfold or more in Caco-2 cells. CONCLUSIONS: Although Caco-2 cells have proven a suitable model for studying carrier-mediated transport in human intestines, the expression of specific transporter and ion channel genes may differ substantially.

Computational quest for understanding the role of astrocyte signaling in synaptic transmission and plasticity.

The complexity of the signaling network that underlies astrocyte-synapse interactions may seem discouraging when tackled from a theoretical perspective. Computational modeling is challenged by the fact that many details remain hitherto unknown and conventional approaches to describe synaptic function are unsuitable to explain experimental observations when astrocytic signaling is taken into account. Supported by experimental evidence is the possibility that astrocytes perform genuine information processing by means of their calcium signaling and are players in the physiological setting of the basal tone of synaptic transmission. Here we consider the plausibility of this scenario from a theoretical perspective, focusing on the modulation of synaptic release probability by the astrocyte and its implications on synaptic plasticity. The analysis of the signaling pathways underlying such modulation refines our notion of tripartite synapse and has profound implications on our understanding of brain function.

Therapy of acute massive pulmonary embolism associated with Klippel-Trenaunay syndrome.

Acute massive pulmonary embolism (PE) is a life-threatening event. Before the era of cardiopulmonary bypass, acute pulmonary embolectomy had been historically attempted in patients with severe hemodynamic compromise. The Klippel-Trenaunay syndrome (KTS) represents a significant life-long risk for major thromboembolic events. We present two young patients with Klippel-Trenaunay syndrome who survived surgical embolectomy after massive PE and cardiopulmonary resuscitation, with good postoperative recovery. Even though the role of surgical embolectomy in massive PE is not clearly defined, with current technology it can be life saving and can lead to a complete recovery, especially in young patients as described in this study.

Indoor air quality in a public building following smoking bans

Introduction: Exposure to environmental tobacco smoke (ETS) is a major environmental risk factor. Indoor contaminants come from a variety of sources, which can include inadequate ventilation, volatile organic compounds (VOCs), biological agents, combustion products, and ETS. Because ETS is one of the most frequent causes of IAQ complaints as well as the high mortality of passive smoking, in June 2004 the University of Geneva made the decision to ban smoking inside the so called "Uni-Mail" building, the biggest Swiss University human science building of recent construction, and the ordinance was applied beginning in October 2004. This report presents the finding related to the IAQ of the "Uni-Mail" building before and after smoking bans using nicotine, suspended dust, condensate and PAHs level in air as tracers to perform an assessment of passive tobacco exposure for non-smokers inside the building. Methods: Respirable particles (RSP) A real time aerosol monitor (model DataRAM)was place at sampling post 1, level ground floor. Condensate It consists in extracting any organic matter taken on the glass fibre filters by MeOH, and then measuring the total absorbent of the MeOH extract to the UV wavelength of 447 nm. Nicotine Nicotine was taken by means of cartridges containing of XAD-4 to the fixed flow of 0.5 L/min. The analytical method used for the determination of nicotine is based on gas chromatography with Nitrogen selective detector GC-NPD. Results: Figure 1 shows the box plot density display of 3 parameters before and after smoking bans for all 7 sampling posts: dust, condensate and nicotine in air in μg/m3. Conclusion: Before the smoking ban, the level of the concentrations of respirable particles (RSP) is raised more, average of the day 320 μg/m3, with peaks of more than 1000 μg/m3, compared with the values of the surrounding air between 22 and 30 μg/m3. The nicotine level is definitely more important (average 5.53 μg/m3, field 1.5 to 17.9 μg/m3). Once the smoking bans inside the building were applied, one notes a clear improvement in terms of concentrations of pollutants. For dust, the concentration fell by 3 times (average: 130 μg/m3, range: 40 to 160 μg/m3) and that of nicotine by 10 times (average: 0.53 μg/m3, range: 0 to 1.69 μg/m3) compared to that found before smoking bans. The outdoor air RSP concentration was 22 μg/m3 or 10 times lower. Nicotine seems to be the best tracer for ETS free of interference, independent of location or season.

SNARE protein expression in synaptic terminals and astrocytes in the adult hippocampus: a comparative analysis.

Several evidences suggest that astrocytes release small transmitter molecules, peptides, and protein factors via regulated exocytosis, implying that they function as specialized neurosecretory cells. However, very little is known about the molecular and functional properties of regulated secretion in astrocytes in the adult brain. Establishing these properties is central to the understanding of the communication mode(s) of these cells and their role(s) in the control of synaptic functions and of cerebral blood flow. In this study, we have set-up a high-resolution confocal microscopy approach to distinguish protein expression in astrocytic structures and neighboring synaptic terminals in adult brain tissue. This approach was applied to investigate the expression pattern of core SNARE proteins for vesicle fusion in the dentate gyrus and CA1 regions of the mouse hippocampus. Our comparative analysis shows that astrocytes abundantly express, in their cell body and main processes, all three protein partners necessary to form an operational SNARE complex but not in the same isoforms expressed in neighbouring synaptic terminals. Thus, SNAP25 and VAMP2 are absent from astrocytic processes and typically concentrated in terminals, while SNAP23 and VAMP3 have the opposite expression pattern. Syntaxin 1 is present in both synaptic terminals and astrocytes. These data support the view that astrocytes in the adult hippocampus can communicate via regulated exocytosis and also indicates that astrocytic exocytosis may differ in its properties from action potential-dependent exocytosis at neuronal synapses, as it relies on a distinctive set of SNARE proteins.

Stiffness tomography exploration of living and fixed macrophages.

Stiffness tomography is a new atomic force microscopy imaging technique that allows highlighting structures located underneath the surface of the sample. In this imaging mode, such structures are identified by investigating their mechanical properties. We present here, for the first time, a description of the use of this technique to acquire detailed stiffness maps of fixed and living macrophages. Indeed, the mechanical properties of several macrophages were studied through stiffness tomography imaging, allowing some insight of the structures lying below the cell's surface. Through these investigations, we were able to evidence the presence and properties of stiff column-like features located underneath the cell membrane. To our knowledge, this is the first evidence of the presence, underneath the cell membrane, of such stiff features, which are in dimension and form compatible with phagosomes. Moreover, by exposing the cells to cytochalasin, we were able to study the induced modifications, obtaining an indication of the location and mechanical properties of the actin cytoskeleton. Copyright © 2012 John Wiley & Sons, Ltd.

CXCR4-activated astrocyte glutamate release via TNFalpha: amplification by microglia triggers neurotoxicity.

Astrocytes actively participate in synaptic integration by releasing transmitter (glutamate) via a calcium-regulated, exocytosis-like process. Here we show that this process follows activation of the receptor CXCR4 by the chemokine stromal cell-derived factor 1 (SDF-1). An extraordinary feature of the ensuing signaling cascade is the rapid extracellular release of tumor necrosis factor-alpha (TNFalpha). Autocrine/paracrine TNFalpha-dependent signaling leading to prostaglandin (PG) formation not only controls glutamate release and astrocyte communication, but also causes their derangement when activated microglia cooperate to dramatically enhance release of the cytokine in response to CXCR4 stimulation. We demonstrate that altered glial communication has direct neuropathological consequences and that agents interfering with CXCR4-dependent astrocyte-microglia signaling prevent neuronal apoptosis induced by the HIV-1 coat glycoprotein, gp120IIIB. Our results identify a new pathway for glia-glia and glia-neuron communication that is relevant to both normal brain function and neurodegenerative diseases.

Phylogenetic alpha and beta diversities of butterfly communities correlate with climate in the western Swiss Alps

The observation of non-random phylogenetic distribution of traits in communities provides evidence for niche-based community assembly. Environment may influence the phylogenetic structure of communities because traits determining how species respond to prevailing conditions can be phylogenetically conserved. In this study, we investigate the variation of butterfly species richness and of phylogenetic - and -diversities along temperature and plant species richness gradients. Our study indicates that butterfly richness is independently positively correlated to temperature and plant species richness in the study area. However, the variation of phylogenetic - and -diversities is only correlated to temperature. The significant phylogenetic clustering at high elevation suggests that cold temperature filters butterfly lineages, leading to communities mostly composed of closely related species adapted to those climatic conditions. These results suggest that in colder and more severe conditions at high elevations deterministic processes and not purely stochastic events drive the assemblage of butterfly communities.

Admissions of patients with alcohol intoxication in the Emergency Department: a growing phenomenon.

QUESTION UNDER STUDY: To investigate the change over time in the number of ED admissions with positive blood alcohol concentration (BAC) and to evaluate predictors of BAC level. METHODS: We conducted a single site retrospective study at the ED of a tertiary referral hospital (western part of Switzerland) and obtained all the BAC performed from 2002 to 2011. We determined the proportion of ED admissions with positive BAC (number of positive BAC/number of admissions). Regression models assessed trends in the proportion of admissions with positive BAC and the predictors of BAC level among patients with positive BAC. RESULTS: A total of 319,489 admissions were recorded and 20,021 BAC tests were performed, of which 14,359 were positive, divided 34.5% female and 65.5% male. The mean (SD) age was 41.7(16.8), and the mean BAC was 2.12(1.04) permille (g of ethanol/liter of blood). An increase in the number of positive BAC was observed, from 756 in 2002 to 1,819 in 2011. The total number of admissions also increased but less: 1.2 versus 2.4 times more admissions with positive BAC. Being male was independently associated with a higher (+0.19 permille) BAC, as was each passing year (+0.03). A significant quadratic association with age indicated a maximum BAC at age 53. CONCLUSION: We observed an increase in the percentage of admissions with positive BAC that was not limited to younger individuals. Given the potential consequences of alcohol intoxication, and the large burden imposed on ED teams, communities should be encouraged to take measures aimed at reducing alcohol intoxication.

Astrocytic dysfunction: insights on the role in neurodegeneration.

For decades, astrocytes have been regarded as passive partners of neurons in central nervous system (CNS) function. Studies of the last 20 years, however, challenged this view by demonstrating that astrocytes possess functional receptors for neurotransmitters and respond to their stimulation via release of gliotransmitters, including glutamate. Notably, astrocytes react to synaptically released neurotransmitters with intracellular calcium ([Ca(2+)]) elevations, which result in the release of glutamate via regulated exocytosis and, possibly, other mechanisms. These findings have led to a new concept of neuron-glia intercommunication where astrocytes play an unsuspected dynamic role by integrating neuronal inputs and modulating synaptic activity. The additional observation that glutamate release from astrocytes is controlled by molecules linked to inflammatory reactions, such as the cytokine tumor necrosis factor alpha (TNFalpha) and prostaglandins (PGs), suggests that glia-to-neuron signalling may be sensitive to changes in the production of these mediators occurring in pathological conditions. Indeed, a local, parenchymal brain inflammatory reaction (neuroinflammation) characterized by astrocytic and microglial activation has been reported in several neurodegenerative disorders, including AIDS dementia complex, Alzheimer's disease and amyotrophic lateral sclerosis. This transition may be accompanied by functional de-regulation and even degeneration of the astrocytes with the consequent disruption of the cross-talk normally occurring between these cells and neurons. Incorrect neuron-astrocyte interactions may be involved in neuronal derangement and contribute to disease development. The findings reported in this review suggest that a better comprehension of the glutamatergic interplay between neurons and astrocytes may provide information about normal brain function and also highlight potential molecular targets for therapeutic interventions in pathology.

Accelerated MR imaging with spread spectrum encoding

We advocate the use of a novel compressed sensing technique for accelerating the magnetic resonance image acquisition process, coined spread spectrum MR imaging or simply s2MRI. The method resides in pre-modulating the signal of interest by a linear chirp, resulting from the application of quadratic phase profiles, before random k-space under-sampling with uniform average density. The effectiveness of the procedure is theoretically underpinned by the optimization of the coherence between the sparsity and sensing bases. The application of the technique for single coil acquisitions is thoroughly studied by means of numerical simulations as well as phantom and in vivo experiments on a 7T scanner. The corresponding results suggest a favorable comparison with state-of-the-art variable density k-space under-sampling approaches.