Phase-locking patterns in a resonate and fire neural model with periodic drive.

In this paper we studied a resonate and fire relaxation oscillator subject to time dependent modulation to investigate phase-locking phenomena occurring in neurophysiological systems. The neural model (denoted LFHN) was obtained by linearization of the FitzHugh-Nagumo neural model near an hyperbolic fixed point and then by introducing an integrate-and-fire mechanism for spike generation. By employing specific tools to study circle maps, we showed that this system exhibits several phase-locking patterns in the presence of periodic perturbations.

Dynamical properties of LFPs from mice with unilateral injection of TeNT.

Local field potential (LFP) recordings were performed from the visual cortex (V1) of a focal epilepsy mouse model. Epilepsy was induced by a unilateral injection of the synaptic blocker tetanus neurotoxin (TeNT). LFP signals were simultaneously recorded from V1 of both hemispheres of each animal under acute and chronic conditions (i.

Ferric citrate controls serum phosphorus in dialysis patients: retrospective data .

Ferric citrate is an approved phosphate binder for use in patients with chronic kidney disease on dialysis. Clinical trials demonstrated that ferric citrate controlled serum phosphorus levels and increased iron stores. The aim of this retrospective chart review was to evaluate real-world bone mineral and anemia parameter data from patients treated with ferric citrate.

Environmental enrichment modulates cortico-cortical interactions in the mouse.

Environmental enrichment (EE) is an experimental protocol based on a complex sensorimotor stimulation that dramatically affects brain development. While it is widely believed that the effects of EE result from the unique combination of different sensory and motor stimuli, it is not known whether and how cortico-cortical interactions are shaped by EE. Since the primary visual cortex (V1) is one of the best characterized targets of EE, we looked for direct cortico-cortical projections impinging on V1, and we identified a direct monosynaptic connection between motor cortex and V1 in the mouse brain.

The synchronization properties of a network of inhibitory interneurons depend on the biophysical model.

The synchronization properties of a pair of coupled fast spiking interneurons are studied by using the theory of weakly coupled oscillators. Four different biophysical models of the single fast spiking interneuron are used and the corresponding results are compared. It is shown that for a pair of identical coupled cells, the synchronization properties are model-dependent.

Calcium signalling in astrocytes and modulation of neural activity.

Starting from the experimental data on ATP evoked calcium responses in astrocytes, a biophysical model describing these phenomena was built. The simulations showed, in agreement with the experimental findings, that the intracellular calcium fluxes mediated by the P2X and P2Y purinoreceptors are responsible for the biphasic ATP evoked calcium response in astrocytes. Then, the modulation effects on the neural dynamics arising from the release of glutamate from astrocyte are also investigated.

Signal processing properties of fast spiking interneurons.

Fast spiking interneurons receive excitatory synaptic inputs from pyramidal cells and a relevant problem is to understand how these cells readout this information. Here this topic is investigated theoretically by using a biophysical modeling of a pair of coupled fast spiking interneuron models. The model predicts, in agreement with the experimental findings, that these cells are capable of transmitting pre-synaptic signals with high temporal precision and transferring high frequency inputs while preserving their relative timing.

A minimal model for the respiratory sinus arrhythmia.

The cardiac and respiratory rhythms in humans are known to be coupled by several mechanisms. In particular, the first rhythm is deeply modulated by the second. In this report we propose a simple operational model for heart rate variability which, taking such modulation into account, reproduces the main features of some experimental sequences of RR intervals recorded from healthy subjects in the resting condition.

Long- and short-time analysis of heartbeat sequences: correlation with mortality risk in congestive heart failure patients.

We analyze RR heartbeat sequences with a dynamic model that satisfactorily reproduces both the long- and the short-time statistical properties of heart beating. These properties are expressed quantitatively by means of two significant parameters, the scaling delta concerning the asymptotic effects of long-range correlation, and the quantity 1-pi establishing the amount of uncorrelated fluctuations. We find a correlation between the position in the phase space (delta, pi) of patients with congestive heart failure and their mortality risk.

Head-down bed rest reduces the breathing rate short-term variability in subjects with orthostatic intolerance.

Orthostatic intolerance is the most serious symptom of cardiovascular deconditioning induced by microgravity. We have showed that in symptomatic subjects the baroreflex control of sinus node is affected by short term simulated microgravity. At present the influence of the respiration on the cardiovascular system in this condition is not clear.

Composition of the blood sampled from surgical drainage after joint arthroplasty: quality of return.

Background: The quality of blood obtained with a device for postoperative blood drainage and autotransfusion (Bellovac-ABT, Astra Tech AB) was investigated in 50 patients who underwent total hip replacement (THR) or total knee replacement (TKR) surgeries.

Study Design And Methods: The Bellovac-ABT drainage set was inserted and blood collection began after skin closure (THR) or 15 minutes after tourniquet deflation (TKR). A collecting bag stayed in place for less than 6 hours.

Gap junctions promote synchronous activities in a network of inhibitory interneurons.

By using a single compartment biophysical model of a fast spiking interneuron the synchronization properties of a pair of cells, coupled by electrical and inhibitory synapses, are investigated. The inhibitory and excitatory synaptic couplings are modeled in order to reproduce the experimental time course of the corresponding currents. It is shown that increasing the conductance value of the electrical synapses enhances the synchronization between the spike trains of the two cells.

Sciatic nerve block with lateral popliteal approach for hallux vagus correction. Comparison between 0.5% bupivacaine and 0.75% ropivacaine.

Aim: In this study the authors compared the clinical profile of 2 local anesthetic drugs in the sciatic nerve block used during hallux valgus correction, a surgical procedure known to be post-operatively extremely painful. Since hallux valgus correction is painful post-operatively, many attempts have been tried to ensure a long-lasting analgesia. Block of the sciatic nerve appears to be the right choice balancing ease to performance, satisfaction of the patient and duration of action.

Mutual information detects a decreased interdependence between RR and SAP in orthostatic intolerance after microgravity condition.

Orthostatic intolerance is the most serious symptom of cardiovascular deconditioning induced by microgravity. However, the exact mechanisms underlying these alterations have not been completely clarified. Several methods for studying the time series of systolic arterial pressure and RR interval have been proposed both in the time and in the frequency domain.

Stochastic resonance in a sinusoidally forced LIF model with noisy threshold.

In this report, the LIF neural model driven by underthreshold sinusoidal signals but with a gaussian-distributed noise on the threshold, is approximated by suitably defining an instantaneous firing (or escape) rate, which depends only on the momentary value of the voltage variable. This allows us to obtain, by analytically solving the relevant equations, the main statistical functions describing the "firing activity"; namely, the probability density function of firing phases and that of interspike intervals. From these functions two quantities can be derived, whose dependence on the noise intensity allows the Stochastic Resonance (SR) to be demonstrated.

Ring wave solutions of a n+1-dimensional Sine-Gordon model.

The dynamical properties of the ring wave solutions of the model psi(tt)- nabla (n) (2)psi+sin psi+ varepsilon sin (psi/2)+alphapsi(t)=0 (00, alpha=0 (or alpha>0) the return effect of the ring wave does not occur only for well defined values of varepsilon.

Effect of 4 hours HD -6 degrees on heart rate variability in symptomatic and non symptomatic subjects.

Orthostatic intolerance is the most serious symptom of cardiovascular deconditioning induced by microgravity exposure. In fact the neural control mechanisms of the cardiovascular system are significantly affected by this condition. Non-invasive measurement of Heart Rate Variability (HRV) have been used as a valuable tool to characterize the ability of neuroendocrine regulatory systems to modulate the cardiovascular function by analyzing the spontaneous fluctuations of arterial pressure and heart period on a beat-to-beat basis.

Average magnitude of heartbeat fluctuations in healthy subjects after exposure to 4 hours head down bed rest.

Orthostatic intolerance, induced by microgravity exposure, has been hypothesized to be related to a disorder of the autonomic control of the cardiovascular system. Non-invasive measurement of Heart Rate Variability (HRV) have been used as a valuable tool to characterize the ability of the autonomic system to modulate the cardiovascular function by analyzing the spontaneous fluctuations of arterial pressure and heart period on a beat-to-beat basis. Concerning this, conflicting results have been reported on the heart rate and blood pressure variability responses during exposure to microG.

Synchronization in a network of fast-spiking interneurons.

Experimental results revealed that in neocortex inhibitory fast-spiking (FS) interneurons interact also by electrical synapses (gap-junctions). They receive sensory information from thalamus and transfer it to principal cells by feedforward inhibition. Moreover, their synchronous discharge enhances their inhibitory control of pyramidal neurons.

The use of remifentanil for bloodless surgical field during vertebral disc resection.

Background: A short hospital stay is nowadays desirable and affordable for a wide range of surgical pathology, respecting safety of care and home discharge. In the present study, the Authors investigated the use of TIVA with propofol/remifentanil during microsurgical vertebral disc resection to maintain a controlled vascular hypotension for bloodless surgical field aiming to reduce the operating time and consequently recovery room length of stay and morbility related to anaesthesia.

Methods: The study took place in a 300 bed Orthopaedics hospital over a period of 3 months and 50 ASA I-II patients were enrolled in this trial; further data are presented for comparison of 50 ASA I-II patients homogeneous for age and sex to the studied population, operated under a standard TIVA with propofol and boluses of fentanyl.

0.25% levo-bupivacaine for interscalene block during shoulder surgery. A survey on 20 patients.

Background: Interscalene brachial plexus block (ISB) is an alternative procedure to general anaesthesia for shoulder surgery, and consents the anaesthetist to easily control postoperative pain that, indeed, is known to be intense and often requires strong analgesic administration. The introduction of regional anaesthesia for this type of surgery, contributed to the relief of acute postoperative pain occurring in the recovery room since the analgesic effects of block persist for several hours after surgery depending upon the selected drug. The aim of this study was to determine the effects of 40 ml of 0.

Effect of aging on responses to autonomic cardiovascular tests.

Cardiovascular deconditioning (CD) and orthostatic intolerance represent some of the major disturbances experienced by astronauts returning on Earth after micro-G exposure. The orthostatic intolerance observed in crew members after space missions has been hypothesized to be related to a disorder of the autonomic control of the cardiovascular system. There is evidence that advanced acing itself may alter the cardiovascular mechanism that underlie the CD.

Nonlinear activity of identified Lymnaea neurons.

Two long-lasting discharges of action potentials were recorded from a buccal cell of the pond snail, respectively, before and after superfusing the preparation with low-calcium solution. The corresponding sequences of interspike intervals were then analysed by the nonlinear prediction methods. The results yield evidence of a small but clear nonlinearity only in the second of analysed tachograms.

Heart rate and blood pressure response to short-term head-down bed rest: a nonlinear approach.

Although it is well-known that prolonged exposure to microgravity environment such as in space travel results in derangements of orthostasis, recent evidence suggests that even short-term exposure may have similar effects and parallels such common examples as prolonged bed rest. Whereas spectral analysis of heart rate and systolic blood pressure have been unable to detect changes, we hypothesized that nonlinear indexes may be better able to uncover such perturbations. Eighteen healthy subjects were exposed to 4-hour head-down tilt, and of these, 4 exhibited fainting.

Interleukin-12 and interleukin-10 production by mononuclear phagocytic cells from breast cancer patients.

Interleukin-10 (IL-10) and Interleukin 12 (IL-12) generation may be regulated by a complex monocyte and macrophage-derived cytokine network and an impairment of the immune system can be observed in neoplastic disease. In this study, we examined the production of these cytokines by phagocytic cells, obtained from breast cancer (BCa)-bearing patients. Our results suggest that an increased IL-10 formation may represent an important regulatory pathway of IL-12 production by BCa mononuclear cells.