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The atria can go into dilation when stenosis or insufficiency of valvular apparatus occurs. The atrial kick contributes to a stroke volume of around 20%, and its contribution increases when there is diastolic dysfunction owing to the elevation of atrial pressure. An increased atrial volume is an independent predictor of adverse cardiovascular events, including stroke and congestive heart failure. Accordingly, accurate measurement of the atrial size has become increasingly relevant to clinical practice. Most clinical studies have used echocardiographic measurements, because echocardiography is the most accepted and best validated modality for atrial volume quantification.

There are several devices for haemodynamic monitoring in the ICU. In low-risk postsurgical patients, haemodynamic monitoring of noninvasive blood pressure, heart rate and EtCO2 will be able to provide sufficient data to diagnose an unexpected haemodynamic instability. In high-risk or in intermediate-risk postsurgical patients, it may be sufficient to perform a SVV monitoring to guide the haemodynamic optimization and the patient’s preload management. In major and more complex surgical procedures, where “mixed shock” can occur (e.g. in abdominal emergency surgery or in a patient with pre-existing cardiomyopathy or valve disease or pulmonary hypertension), a complete and more invasive haemodynamic assessment must be performed with a calibrated device for the cardiac output measurement or a combined PAC with a SVV measuring tool.

Recent advances in fast volumetric imaging have enabled rapid generation of large amounts of multi-dimensional functional data. While many computer frameworks exist for data storage and analysis of the multi-gigabyte Ca 2+ imaging experiments in neurons, they are less useful for analyzing Ca 2+ dynamics in astrocytes, where transients do not follow a predictable spatio-temporal distribution pattern. In this manuscript, we provide a detailed protocol and commentary for recording and analyzing three-dimensional (3D) Ca 2+ transients through time in GCaMP6f-expressing astrocytes of adult brain slices in response to axonal stimulation, using our recently developed tools to perform interactive exploration, filtering, and time-correlation analysis of the transients. In addition to the protocol, we release our in-house software tools and discuss parameters pertinent to conducting axonal stimulation/response experiments across various brain regions and conditions. Our software tools are available from the Volterra Lab webpage at https://wwwfbm.unil.ch/dnf/group/glia-an-active-synaptic-partner/member/volterra-andrea-volterra in the form of software plugins for Image J (NIH)-a de facto standard in scientific image analysis. Three programs are available: MultiROI_TZ_profiler for interactive graphing of several movable ROIs simultaneously, Gaussian_Filter5D for Gaussian filtering in several dimensions, and Correlation_Calculator for computing various cross-correlation parameters on voxel collections through time.

Summary Objective Nonconvulsive status epilepticus (ncSE) is a severe condition that may result in neurologic sequelae and epilepsy resistant to pharmacologic treatment. We analyze here seizure and electroencephalography (EEG) patterns and their correlation to the development of a chronic epileptic condition in a guinea pig model of focal ncSE induced by intrahippocampal injection of kainic acid (KA). Methods Electrobehavioral patterns during ncSE induced by unilateral injection of 1 μg of KA in the CA1 region of the hippocampus were characterized by continuous video-EEG monitoring in 13 guinea pigs bilaterally implanted with recording electrodes in the hippocampus and neocortex. Results Video-EEG analysis demonstrates a high variability of seizure type and duration during KA-induced ncSE. Seizures showed focal signs correlated with diverse epileptiform EEG discharge distributions, either diffuse or localized. Nonfocal (bilateral motor) signs during seizures most likely correlated with a diffuse EEG pattern. The evolution into a chronic epileptic condition correlated neither with the severity of seizure pattern nor with the diffusion of the EEG discharges observed during the ncSE. Significance Video-EEG monitoring in a guinea pig model of ncSE induced by unilateral hippocampal injection of KA demonstrates a high variability of electrobehavioral patterns. We demonstrate that the seizure severity score during focal ncSE is not a predictor of the evolution into a chronic epileptic condition of mesial temporal lobe epilepsy.

Duration >120 minutes of extracorporeal circulation (ECC) during cardiopulmonary bypass procedure was associated to an increased risk of candidemia in the intensive care unit (ICU). To evaluate oral nystatin prophylaxis in cardiac surgery considering its exclusive effect on Candida, in the absence of systemic effects and selection of resistant strains to polyene. We conducted an observational study in the postcardiac surgery ICU of Policlinico "Umberto I" of Rome. From January 2014, all patients with a prolonged ECC >120 minutes were systematically treated with oral nystatin (Prophylaxis group). This group was compared with all patients hospitalised in the same ICU, who have not received oral nystatin after ECC >120 minutes (No prophylaxis group). Overall, 672 consecutive patients were analyzed: 318 (47.3%) patients belonged to the no prophylaxis group, and 354 (52.7%) patients to the prophylaxis group. Diagnosis of candidemia was confirmed in 7 (2.2%) patients, all belonged to the no prophylaxis group. At multivariate analysis, oral nystatin prophylaxis showed a protective effect for development of candidemia after cardiac surgery. Oral nystatin prophylaxis, in patients who underwent a ECC >120 minutes, seems to reduce development of candidemia; however, the real efficacy of such prophylaxis approach requires further investigation.

Astrocyte communication is typically studied by two-dimensional calcium ion (Ca

Summary Purpose: Models of temporal lobe epilepsy are commonly utilized to study focal epileptogenesis and ictogenesis. The criteria that define animal models representative of human mesial temporal lobe may vary in different laboratories. We describe herein a focal epilepsy model of mesial temporal (hippocampal) origin that relies on the analysis of interictal and ictal electroencephalography (EEG) patterns and on their correlation with seizure symptoms and neuropathologic findings. The study is based on guinea pigs, a species seldom utilized to develop chronic epilepsy models. Methods: Young adult guinea pigs were bilaterally implanted under isoflurane anesthesia with epidural electrodes over somatosensory cortex and depth electrodes in CA1 hippocampal region. A stainless steel guide cannula was positioned unilaterally in the right dorsal hippocampus to inject 1 μl of 0.9% NaCl solution containing 1 μg kainic acid (KA). One week after surgery, continuous 24 h/day video-EEG monitoring was performed 48 h before and every other week after KA injection, for no

We have generated an experimental ‘double-hit’ model of chronic epilepsy to recapitulate the co-existence of abnormal cortical structure and frequently recurrent seizures as observed in human focal cortical dysplasia. We induced cortical malformations by exposing rats prenatally to methylazoxymethanol acetate and triggered status epilepticus and recurrent seizures in adult methylazoxymethanol acetate rats with pilocarpine. We studied the course of epilepsy and the long-term morphologic and molecular changes induced by the occurrence of status epilepticus and subsequent chronic epilepsy in the malformed methylazoxymethanol acetate exposed brain. Behavioural and electroencephalographic analyses showed that methylazoxymethanol acetate pilocarpine rats develop more severe epilepsy than naive rats. Morphologic and molecular analyses demonstrated that status epilepticus and subsequent seizures, but not pilocarpine treatment per se , was capable of affecting both cortical architectural and N -methyl-d-aspartate receptor abnormalities induced by methylazoxymethanol acetate. In particular, cortical thickness was further decreased and N -methyl-d-aspartate regulatory subunits were recruited at the postsynaptic membrane. In addition, methylazoxymethanol acetate pilocarpine rats showed abnormally large cortical pyramidal neurons with neurofilament over-expression. These neurons bear similarities to the hypertrophic/dysmorphic pyramidal neurons observed in acquired human focal cortical dysplasia. These data show that status epilepticus sets in motion a pathological process capable of significantly changing the cellular and molecular features of pre-existing experimental cortical malformations. They suggest that seizure recurrence in human focal cortical dysplasia might be an additional factor in establishing a pathological circuitry that favours chronic neuronal hyperexcitability. * Abbreviations : MAM : methylazoxymethanol acetate NMDA : N -methyl- d -aspartate PILO : pilocarpine

Positron emission tomography / computed tomography (PET/CT) and PET / magnetic resonance (PET/MR) with several tracers has been used to investigate the cellular physiopathology of brain tumors. For prediction of tumor grading, [18F]-fluorodeoxyglucose ([18F]-FDG) is more accurate than most amino acid tracers, while amino acid tracers, typically 11C-methionine, L-3,4-dihydroxyphenylalanine ([18F]-fluorodopa) and to a lesser extent O-(2-[18F]-fluoroethyl)-L-tyrosine, are more accurate than [18F]-FDG for the distinction between tumor recurrence and radiation necrosis. Changes after therapy as well as baseline tracer uptake in untreated patients have prognostic value. Post-surgical scans can be used for identification of residual tumor. PET, in combination with MR, is increasingly used for the definition of the tumor volume that has to be targeted by radiation therapy. Identification of the metabolically active volume can also be used to direct stereotaxic biopsy. Other tracers have been developed to explore different biochemical processes, for example hypoxia ([18F]-fluoromisonidazole), DNA synthesis (3-deoxy-3-[18F]-fluorothymidine, and membrane proliferation (radiolabeled choline). However, these radiopharmaceuticals presently have a more uncertain role in the clinical routine, even though some interesting results are emerging from the first clinical studies. The recent development of PET/MR hybrid scanners has represented a technological breakthrough with immediate consequences on improved diagnostic and research capabilities, as well as on logistical issues favorable for the patient, who can perform two examinations at a single time (“one-stop-shop”). This is particularly true for simultaneous systems in which the PET is within the magnetic field and the traditional PET detection system, classically based on photomultipliers, is replaced by magnetic field-insensitive avalanche photodiodes or silicon-based elements. The combination of the PET/ and MR has already proved to provide a complex synergistic effect. However, the use of PET/MR scanners is currently limited to restricted research centers owing to high costs, demanding maintenance, and necessary interdisciplinary personnel.

Summary Purpose Dravet syndrome (DS) is caused by dominant mutations of the SCN1A gene, encoding the NaV1.1 sodium channel α subunit. Gene targeted mouse models of DS mutations replicate patients' phenotype and show reduced γ-aminobutyric acid (GABA)ergic inhibition. However, little is known on the properties of network hyperexcitability and on properties of seizure generation in these models. In fact, seizures have been studied thus far with surface electroencephalography (EEG), which did not show if specific brain regions are particularly involved. We have investigated hyperexcitability and epileptiform activities generated in neuronal networks of a mouse model of DS. Methods We have studied heterozygous NaV1.1 knock-out mice performing field potential recordings in combined hippocampal/cortical slices in vitro and video/depth electrode intracerebral recordings in vivo during hyperthermia-induced seizures. Key Findings In slices, we have disclosed specific signs of hyperexcitability of hippocampal circuits in both the pre-epileptic and epileptic periods, and a specific epileptiform activity was generated in the hippocampus upon application of the convulsant 4-aminopyridine in the epileptic period. During in vivo hyperthermia-induced seizures, we have observed selective hippocampal activity in early preictal phases and pronounced hippocampal activity in the ictal phase. Significance We have identified specific epileptiform activities and signs of network hyperexcitability, and disclosed the important role of the hippocampus in seizure generation in this model. These activities may be potentially used as targets for screenings of antiepileptic approaches.

The current debate on the classification of seizures and epilepsies introduced the concept of epileptic networks that define focal epileptiform activities (Berg et al., 2010). The term epileptic network extends the notion of epileptic focus and introduces the idea that enhanced excitability within ensemble of strongly interconnected neurons/networks may promote the generation of region-specific synchronous pathologic discharges. This hypothesis has led to the proposition that some forms of idiopathic (and even acquired) epilepsy may represent a specific network dysfunction, due to enduring propensity of the network/system itself as a whole to generate seizures (Avanzini et al., 2012). The existence of predetermined functional network substrates supporting the generation of synchronous activity patterns may represent one of the prerequisites for the definition of system or network epilepsy. Studies in a number of animal models of generalized epilepsy demonstrated that specific patterns of epileptiform discharges entrain the thalamocortical system (Gloor & Fariello, 1988; Danober et al., 1998; van Luijtelaar & Sitnikova, 2006; Leresche et al., 2012). The hippocampal-parahippocampal region represents another cortical system that is activated as a whole in models of temporal lobe epilepsy and limbic seizures (Avoli et al., 2002; Uva et al., 2005; McIntyre & Gilby, 2008). To gain more information about the cellular and network determinants of seizure generation in these areas, detailed in vitro studies were performed on brain tissue slices. In vitro slices, however, do not allow for an extensive and thorough analysis of network activities, because of the obvious limitations of the preparation itself. Isolated en block brain preparations (de Curtis et al., 1994; Luhmann et al., 2000; Khalilov et al., 2003; Uva et al., 2005) could be better suited for studying the propensity of extended, interconnected cortical regions to generate seizure-like events. We have previously reported that coexisting, but regionally independent, seizure patterns can be induced in brains of guinea pigs maintained in vitro by arterial perfusion by acute pharmacologic manipulations with proepileptic drugs (de Curtis et al., 1994; Uva et al., 2005). Moreover, in Carriero et al. (2010) we have recently demonstrated that in the presence of the potassium channel blocker 4-aminopyridine (4AP; Llinas et al., 1976; Avoli & Perreault, 1987; Perreault & Avoli, 1991), the olfactory cortices and the hippocampal-parahippocampal regions generate independent seizure-like discharges that do not reciprocally interact (Carriero et al., 2010), despite the anatomic and functional connections, and that show a completely different seizure pattern. We extend here the study of ictal discharges recorded in the olfactory system, which is known to be a seizure-prone region (Piredda & Gale, 1985), in this model of ictogenesis, to verify whether this region can be considered as a network system for seizure generation and to unveil the network and cellular mechanisms that sustain this peculiar activity.

INTRODUCTION Astrocytes translate incoming information and generate functional outputs via Ca 2+ signaling. Thereby, they respond to neuronal activity, producing downstream modulation of synaptic functions, and may participate in hemodynamics regulation. Deciphering the “Ca 2+ language” of astrocytes is therefore essential for defining their roles in brain physiology and pathology. However, the specifics of astrocytic Ca 2+ signaling are still poorly understood, and recent studies producing inconsistent or contradictory results have fostered debate on the actual role of astrocytes in synaptic and vascular functions. RATIONALE A neglected potential source of inconsistencies lies in the way astrocytic Ca 2+ signaling has been studied to date, mostly by conventional two-dimensional (2D) imaging, which assumes that sampling a single (~1 μm) focal plane is representative of the entire astrocytic cell. This is, however, dubious given that astrocytes are highly 3D cells, entertain heterogeneous 3D relations with neighboring structures, and display Ca 2+ signals on a local scale. Therefore, we developed a new method to three-dimensionally scan entire astrocytes and observe full-cell Ca 2+ dynamics. RESULTS With our 3D approach, we sampled astrocytes at a sufficient rate to detect events with durations of >1.5 s throughout the cell, and faster ones in selected substructures. We found that Ca 2+ activity in an individual astrocyte is heterogeneously scattered throughout the cell, largely compartmented within each region, and preponderantly local. The majority resides in the “gliapil,” the peripheral region composed of fine (optically subresolved) structures occupying ∼75% of the astrocyte volume. Within the central (resolvable) “core,” the soma is mostly inactive, whereas processes are frequently active yet show widely different activity between them. Even in individual processes, activity distributes heterogeneously, with alternating “hot” and “cold” spots. We performed 3D imaging in awake mice and in adult brain slices. Activity in vivo was faster and more frequent, particularly in endfeet, yet similar in properties and cellular distribution to slices, except for the presence of cell-wide “global” Ca 2+ events mainly associated with mouse movement. Contrary to current beliefs, global events were not sweeping waves, but rather consisted of multifocal Ca 2+ elevations that started at multiple gliapil loci and then spread to the core. At the vascular interface, astrocytic Ca 2+ activity was mostly restricted to individual endfeet, even to their fractions, and only occasionally coordinated with the endfoot process or the rest of the astrocyte. Two or more endfeet were mainly asynchronous, even when enwrapping the same vessel. Astrocytic structures and axons intersected three-dimensionally, and minimal axonal activity (individual action potentials) produced time-correlated astrocytic Ca 2+ elevations in small spots ( CONCLUSION We provide the first comprehensive 3D map of Ca 2+ activity in an individual astrocyte. Its widespread, heterogeneous, local, and mostly 3D nature confirms the appropriateness of our whole-cell imaging approach. Past 2D studies, often focusing on somatic Ca 2+ dynamics, inadequately described the emerging richness and complexity of the astrocyte activity, notably at astrocyte-synapse and astrocyte-vascular interfaces, where activity is small, fast, and frequent. In this context, we can foresee future challenges in extending studies to the gliapil, whose structures fall below current optical resolution, and in reporting the complete gamut of astrocyte Ca 2+ signals at the whole-cell scale, both requiring technical advances. Nonetheless, the technique demonstrated here promises to make 3D Ca 2+ imaging the state-of-the-art approach for Ca 2+ studies addressing the role of astrocytes in brain function.

Models of temporal lobe epilepsy are commonly utilized to study focal epileptogenesis and ictogenesis. The criteria that define animal models representative of human mesial temporal lobe may vary in different laboratories. We describe herein a focal epilepsy model of mesial temporal (hippocampal) origin that relies on the analysis of interictal and ictal electroencephalography (EEG) patterns and on their correlation with seizure symptoms and neuropathologic findings. The study is based on guinea pigs, a species seldom utilized to develop chronic epilepsy models. Young adult guinea pigs were bilaterally implanted under isoflurane anesthesia with epidural electrodes over somatosensory cortex and depth electrodes in CA1 hippocampal region. A stainless steel guide cannula was positioned unilaterally in the right dorsal hippocampus to inject 1 μl of 0.9% NaCl solution containing 1 μg kainic acid (KA). One week after surgery, continuous 24 h/day video-EEG monitoring was performed 48 h before and every other week after KA injection, for no1 month. EEG data were recorded wide-band at 2 kHz. After video-EEG monitoring, brains were analyzed for thionine and Timm staining and glial fibrillary acid protein (GFAP) immunostaining. Unilateral injection of KA in dorsal hippocampus of guinea pigs induces an acute nonconvulsive status epilepticus (SE) that terminates within 24 h (n = 22). Chronic seizures with very mild motor signs (undetectable without EEG monitoring) and highly variable recurrence patterns appear in 45.5% (10 of 22) KA-treated animals, with variable delays from the initial SE. In these animals interictal events, CA1 cell loss, gliosis, and altered Timm staining pattern were observed. The induction of a chronic condition did not correlate with the duration of the nonconvulsive acute SE, but correlated with the extension and quality of neuropathologic damage. We demonstrate that a model of hippocampal (mesial temporal lobe) epilepsy can be developed in the guinea pig by intrahippocampal injection of KA. Seizure events in this model show little behavioral signs and may be overlooked without extensive video-EEG monitoring. The establishment of a chronic epileptic condition correlates with the extension of the hippocampal damage (mainly cell loss and gliosis) and not with the intensity of the initial SE.

In vitro studies performed on brain slices demonstrate that the potassium channel blocker 4-aminopyridine (4AP, 50 μM) discloses electrographic seizure activity and interictal discharges. These epileptiform patterns have been further analyzed here in a isolated whole guinea pig brain in vitro by using field potential recordings in olfactory and limbic structures. In 8 of 13 experiments runs of fast oscillatory activity ( fast runs, FRs) in the piriform cortex (PC) propagated to the lateral entorhinal cortex (EC), hippocampus and occasionally to the medial EC. Early and late FRs were asynchronous in the hemispheres showed different duration [1.78 ± 0.51 and 27.95 ± 4.55 (SD) s, respectively], frequency of occurrence (1.82 ± 0.49 and 34.16 ± 6.03 s) and frequency content (20–40 vs. 40–60 Hz). Preictal spikes independent from the FRs appeared in the hippocampus/EC and developed into ictal-like discharges that did not propagate to the PC. Ictal-like activity consisted of fast activity with onset either in the hippocampus ( n = 6) or in the mEC ( n = 2), followed by irregular spiking and sequences of diffusely synchronous bursts. Perfusion of the N-methyl-d-aspartate receptor antagonist 2-amino-5-phosphonopentanoic acid (100 μM) did not prevent FRs, increased the duration of limbic ictal-like discharges and favored their propagation to olfactory structures. The AMPA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (50 μM) blocked ictal-like events and reduced FRs. In conclusion, 4AP-induced epileptiform activities are asynchronous and independent in olfactory and hippocampal-entorhinal regions. Epileptiform discharges in the isolated guinea pig brain show different pharmacological properties compared with rodent in vitro slices.

The olfactory tubercle (OT) is a cortical component of the olfactory system involved in reward mechanisms of drug abuse. This region covers an extensive part of the rostral ventral cerebrum and is relatively poorly studied. The intrinsic network interactions evoked by olfactory input are analyzed in the OT of the in vitro isolated guinea pig brain by means of field potential analysis and optical imaging of voltage-sensitive signals. Stimulation of the lateral olfactory tract induces a monosynaptic response that progressively decreases in amplitude from lateral to medial. The monosynaptic input induces a disynaptic response that is proportionally larger in the medial portion of the OT. Direct stimulation of the piriform cortex and subsequent lesion of this pathway showed the existence of an associative disynaptic projection from the anterior part of the piriform cortex to the lateral part of the OT that integrates with the component mediated by the local intra-OT collaterals. Optical and electrophysiological recordings of the signals evoked by stimulation of the olfactory tract during arterial perfusion with the voltage-sensitive dye di-2-ANEPEQ confirmed the pattern of distribution of the mono and disynaptic responses in the OT. Finally, current source density analysis of laminar profiles recorded with 16-channel silicon probes confirmed that the monosynaptic and disynaptic potentials localize in the most superficial and the deep portions of the plexiform layer I, as suggested by previous reports. This study sets the standard for further analysis of the modulation of network properties in this largely unexplored brain region.