Revisiting the frequency domain: the multiple and partial coherence of cerebral blood flow velocity in the assessment of dynamic cerebral autoregulation

Despite advances in modelling dynamic autoregulation, only part of the variability of cerebral blood flow velocity (CBFV) in the low frequency range has been explained. We investigate whether a multivariate representation can be used for this purpose. Pseudorandom sequences were used to inflate thigh cuffs and to administer 5% CO2. Multiple and partial coherence were estimated, using arterial blood pressure (ABP), end-tidal CO2 (EtCO2) and resistance area product as input and CBFV as output variables. The inclusion of second and third input variables increased the amount of CBFV variability that can be accounted for (p  <  10−4 in both cases). Partial coherence estimates in the low frequency range (<0.07 Hz) were not influenced by the use of thigh cuffs, but CO2 administration had a statistically significant effect (p  <  10−4 in all cases). We conclude that the inclusion of additional inputs of a priori known physiological significance can help account for a greater amount of CBFV variability and may represent a viable alternative to more conventional non-linear modelling. The results of partial coherence analysis suggest that dynamic autoregulation and CO2 reactivity are likely to be the result of different physiological mechanisms

The prokineticin system : an interface between neural inflammation and pain

Prokineticins (PK) 1 and 2 belong to a new family of chemokines capable to interact with two different G coupled receptors: Prokineticin receptor (PKR)1 and 2. Both prokineticins and their receptors are widely distributed in different tissues and regulate several biological functions. In particular, a role of the PK system in inflammation and nociception has been established. PKRs are expressed in regions of the nervous system associated with pain and in primary sensitive neurons they colocalize with transient potential receptor vanilloid-TRPV1 providing an anatomical interaction in nociceptor sensitization. Moreover, PKs are strongly upregulated in immune and glial cells and sustain a proinflammatory loop in inflamed tissues. Recent evidences indicate that the block of the PK system represents a promising strategy to contrast inflammation and pain

Multi-domain analysis and prediction of the light emitted by an inductively coupled plasma jet

Inductively coupled plasma wind tunnels are crucial for replicating hypersonic flight conditions in ground testing. Achieving the desired conditions (e.g., stagnation-point heat fluxes and enthalpies during atmospheric reentry) requires a careful selection of operating inputs, such as mass flow, gas composition, nozzle geometry, torch power, chamber pressure, and probing location along the plasma jet. The study presented herein focuses on the influence of the torch power and chamber pressure on the plasma jet dynamics within the 350 kW Plasmatron X ICP facility at the University of Illinois at Urbana-Champaign. A multi-domain analysis of the jet behavior under selected power-pressure conditions is presented in terms of emitted light measurements collected using high-speed imaging. We then use Gaussian Process Regression to develop a data-informed learning framework for predicting Plasmatron X jet profiles at unseen pressure and power test conditions. Understanding the physics behind the dynamics of high-enthalpy flows, particularly plasma jets, is the key to properly design material testing, perform diagnostics, and develop accurate simulation modelsComment: 22 pages (including figures, appendix, and references); 13 figure

Coherent averaging of pseudorandom binary stimuli: is the dynamic cerebral autoregulatory response symmetrical?

Objective: Previous studies on cerebral autoregulation have shown the existence of hemispheric symmetry, which may be altered in stroke and traumatic brain injury. There is a paucity of data however on whether the response is symmetrical between those disturbances that cause cerebral hyperperfusion, to those that cause hypoperfusion. Our aim was to investigate whether the responses of cerebral autoregulation to haemodynamic stimuli of different directions are symmetrical. &#13; Approach: Using a previously described assessment method, we employed coherent averaging of the cerebral blood flow velocity (CBFV) responses to thigh cuff inflation and deflation, as driven by pseudorandom binary sequences, whilst simultaneously altering the inspired CO2. The symmetry of the autoregulatory response was assessed with regards to two parameters, its speed and gain. Using the first harmonic method, critical closing pressure (CrCP) and resistance area product (RAP) were estimated, and the gain of the autoregulatory response was calculated by performing linear regression between the coherent averages of arterial blood pressure (ABP) and CBFV, ABP and CrCP and finally ABP and RAP. A two-way repeated measures ANOVA was used to assess for the effect of the direction of change in ABP and the method of CO2 administration. &#13; Main results: Our results suggest that whilst the direction of ABP change does not have a significant effect, the effect of CO2 administration method is highly significant (p&lt;10-4). &#13; Significance: This is the first report to report to demonstrate the symmetry of the autoregulatory response to stimuli of different directions as well as the short term dynamics of RAP and CrCP under intermittent and constant hypercapnia. As haemodynamic stimulus direction does not appear to have an influence, our findings validate previous work done using different assessment methods

Oppioidi, MDMA, marijuana e l&#8217;immunosoppressione : quale rilevanza clinica?

Obiettivi: Lo scopo di questa breve rassegna \ue8 di riassumere i dati disponibili in letteratura sulle interazioni tra alcune sostanze d\u2019abuso, quali le amfetamine e i loro derivati, la marijuana e gli oppioidi, e la funzione immune. L\u2019 importanza di questi aspetti nella medicina dell\u2019addiction non \ue8 ancora chiara. Metodi: Sono state prese in considerazioni le pubblicazioni pi\uf9 significative presenti in Medline, identificate con opportune parole chiave e scelte secondo l\u2019esperienza degli autori sull\u2019argomento. Risultati: Gli effetti sul sistema immune possono essere indiretti, attraverso l\u2019interazioni dei farmaci con recettori o trasportatori presenti nel sistema nervoso centrale o attraverso l\u2019attivazione di recettori espressi dalle cellule immuni. In particolare per la marijuana e gli oppioidi sono stati chiaramente identificati i recettori specifici su tutte le popolazioni di cellule immuni. Un aspetto comune della immunomodulazione di tutte le sostanze d\u2019abuso sembra essere quello di perturbare l\u2019equilibrio omeostatico tra i linfociti Thelper1, pro infiammatori, in favore dei Thelper 2, di tipo antinfiammatori. Esiste quindi oggi un\u2019ampia letteratura che dimostra come le sostanze d\u2019abuso alterino la funzione immune nell\u2019animale da esperimento e in vitro anche in cellule umane. Nell\u2019animale da esperimento inoltre \ue8 sempre pi\uf9 chiara l\u2019esistenza di una correlazione tra l\u2019effetto immunosoppressivo e l\u2019incidenza di infezioni. L\u2019elevata incidenza di patologie infettive nei soggetti che abusano di sostanze \ue8 ben nota, ma molto pochi sono ancora gli studi nell\u2019uomo che cercano di correlare gli effetti immunosoppressivi con la maggior suscettibilit\ue0 alle infezioni. Conclusione: L\u2019effetto immunosoppressivo dei farmaci d \u2018abuso \ue8 stato ben documentato. Nell\u2019uomo per\uf2 non \ue8 possibile al momento dimostrare l\u2019esistenza di una relazione di causa effetto tra questi effetti ed un aumentato rischio di infezioni. Ulteriori studi saranno necessari per meglio comprendere questo aspetto

Functional Living Skills: A Non-Immersive Virtual Reality Training for Individuals with Major Neurocognitive Disorders

The loss of functional living skills (FLS) is an essential feature of major neurocognitive disorders (M-NCD); virtual reality training (VRT) offers many possibilities for improving FLS in people with M-NCD. The aim of our study was to verify the effectiveness of a non-immersive VRT on FLS for patients with M-NCD. VRT was carried out for 10 to 20 sessions, by means of four 3D apps developed in our institute and installed on a large touch screen. The experimental group (EG) and the control group (CG) included 24 and 18 patients with M-NCD, respectively. They were administered the in vivo test (in specific hospital places reproducing the natural environments) at T1 (pre-training) and T3 (post-training); at T2, only EG was administered VRT. Statistically significant differences between EG and CG in all the in vivo tests were found in the number of correct responses; during VRT, the number of correct responses increased, while the execution times and the number of clues decreased. The improvement in the in vivo tests appeared to be related to the specific VRT applied. The satisfaction of participants with the VRT was moderate to high

Dynamic cerebral autoregulation after intracerebral hemorrhage: A case-control study

<p>Abstract</p> <p>Background</p> <p>Dynamic cerebral autoregulation after intracerebral hemorrhage (ICH) remains poorly understood. We performed a case-control study to compare dynamic autoregulation between ICH patients and healthy controls.</p> <p>Methods</p> <p>Twenty-one patients (66 ± 15 years) with early (< 72 hours) lobar or basal ganglia ICH were prospectively studied and compared to twenty-three age-matched controls (65 ± 9 years). Continuous measures of mean flow velocity (MFV) in the middle cerebral artery and mean arterial blood pressure (MAP) were obtained over 5 min. Cerebrovascular resistance index (CVR_i) was calculated as the ratio of MAP to MFV. Dynamic cerebral autoregulation was assessed using transfer function analysis of spontaneous MAP and MFV oscillations in the low (0.03-0.15 Hz) and high (0.15-0.5 Hz) frequency ranges.</p> <p>Results</p> <p>The ICH group demonstrated higher CVR_icompared to controls (ipsilateral: 1.91 ± 1.01 mmHg·s·cm^-1, <it>p </it>= 0.04; contralateral: 2.01 ± 1.24 mmHg·s·cm^-1, <it>p </it>= 0.04; vs. control: 1.42 ± 0.45 mmHg·s·cm^-1). The ICH group had higher gains than controls in the low (ipsilateral: 1.33 ± 0.58%/mmHg, <it>p </it>= 0.0005; contralateral: 1.47 ± 0.98%/mmHg, <it>p </it>= 0.004; vs. control: 0.82 ± 0.30%/mmHg) and high (ipsilateral: 2.11 ± 1.31%/mmHg, <it>p </it>< 0.0001; contralateral: 2.14 ± 1.49%/mmHg, <it>p </it>< 0.0001; vs. control: 0.66 ± 0.26%/mmHg) frequency ranges. The ICH group also had higher coherence in the contralateral hemisphere than the control (ICH contralateral: 0.53 ± 0.38, <it>p </it>= 0.02; vs. control: 0.38 ± 0.15) in the high frequency range.</p> <p>Conclusions</p> <p>Patients with ICH had higher gains in a wide range of frequency ranges compared to controls. These findings suggest that dynamic cerebral autoregulation may be less effective in the early days after ICH. Further study is needed to determine the relationship between hematoma size and severity of autoregulation impairment.</p

X-ray Micro-Tomography of Ablative Heat Shield Materials

X-ray micro-tomography is a non-destructive characterization technique that allows imaging of materials structures with voxel sizes in the micrometer range. This level of resolution makes the technique very attractive for imaging porous ablators used in hypersonic entry systems. Besides providing a high fidelity description of the material architecture, micro-tomography enables computations of bulk material properties and simulations of micro-scale phenomena. This presentation provides an overview of a collaborative effort between NASA Ames Research Center and Lawrence Berkeley National Laboratory, aimed at developing micro-tomography experiments and simulations for porous ablative materials. Measurements are carried using x-rays from the Advanced Light Source at Berkeley Lab on different classes of ablative materials used in NASA entry systems. Challenges, strengths and limitations of the technique for imaging materials such as lightweight carbon-phenolic systems and woven textiles are discussed. Computational tools developed to perform numerical simulations based on micro-tomography are described. These enable computations of material properties such as permeability, thermal and radiative conductivity, tortuosity and other parameters that are used in ablator response models. Finally, we present the design of environmental cells that enable imaging materials under simulated operational conditions, such as high temperature, mechanical loads and oxidizing atmospheres.Keywords: Micro-tomography, Porous media, Ablatio

Teleneuroriabilitazione cognitiva per le funzioni di vita quotidiana: applicazione nella disabilità intellettiva e nelle demenze

Presentazione fatta da V. Catania a Innovabiomed 2021