Hydrogen gas and its role in cell signalling

This is the author accepted manuscript. The final version is available from CAB International via the DOI in this record. Hydrogen gas (H2) was once thought to be inert in biological systems but it has now become apparent that exposure of a wide range of organisms, including animals and plants, to H2or hydrogen-rich water has beneficial effects. It is involved in plant development, and alleviation of stress and illness, such as reperfusion injury. Here, an overview of how H2interacts with organisms is given

Convexity subarachnoid haemorrhage has a high risk of intracerebral haemorrhage in suspected cerebral amyloid angiopathy

The risk of future symptomatic intracerebral haemorrhage (sICH) remains uncertain in patients with acute convexity subarachnoid haemorrhage (cSAH) associated with suspected cerebral amyloid angiopathy (CAA). We assessed the risk of future sICH in patients presenting to our comprehensive stroke service with acute non-traumatic cSAH due to suspected CAA, between 2011 and 2016. We conducted a systematic search and pooled analysis including our cohort and other published studies including similar cohorts. Our hospital cohort included 20 patients (mean age 69 years; 60% male); 12 (60%) had probable CAA, and 6 (30%) had possible CAA according to the modified Boston criteria; two did not meet CAA criteria because of age <55 years, but were judged likely to be due to CAA. Fourteen patients (70%) had cortical superficial siderosis; 12 (60%) had cerebral microbleeds. Over a mean follow-up period of 19 months, 2 patients (9%) suffered sICH, both with probable CAA (annual sICH risk for probable CAA 8%). In a pooled analysis including our cohort and eight other studies (n = 172), the overall sICH rate per patient-year was 16% (95% CI 11-24%). In those with probable CAA (n = 104), the sICH rate per patient-year was 19% (95% CI 13-27%), compared to 7% (95% CI 3-15%) for those without probable CAA (n = 72). Patients with acute cSAH associated with suspected CAA are at high risk of future sICH (16% per patient-year); probable CAA might carry the highest risk

The Cerebral Haemorrhage Anatomical RaTing inStrument (CHARTS): Development and assessment of reliability.

PURPOSE: The causes, risk factors and prognosis of spontaneous intracerebral haemorrhage (ICH) are partly determined by anatomical location (specifically, lobar vs. non-lobar (deep and infratentorial) regions). We systematically developed a rating instrument to reliably classify ICH location. METHODS: We used a two-stage iterative Delphi-style method for instrument development. The resultant Cerebral Haemorrhage Anatomical RaTing inStrument (CHARTS) was validated on CT and MRI scans from a cohort of consecutive patients with acute spontaneous symptomatic ICH by three independent raters. We tested interrater and intrarater reliability using kappa statistics. RESULTS: Our validation cohort included 227 patients (58% male; median age: 72.4 (IQR: 67.1-74.6)). The interrater reliability for the main analyses (i.e. including any lobar ICH; all deep and infratentorial anatomical categories (lentiform, caudate thalamus; brainstem; cerebellum); and uncertain location) was excellent (all kappa values>0.80) both in pair-wise between-rater comparisons and across all raters. The intrarater reliability was substantial to almost perfect (k=0.83; 95%CI: 0.77-0.88 and k=0.95; 95%CI: 0.92-0.96 respectively). All kappa statistics remained consistent for individual cerebral lobar regions. CONCLUSIONS: The CHARTS instrument can be used to reliably and comprehensively map the anatomical location of spontaneous ICH, and may be helpful for studying important questions regarding causes, risk factors, prognosis, and for stratification in clinical trials

Finite-size and correlation-induced effects in Mean-field Dynamics

The brain's activity is characterized by the interaction of a very large number of neurons that are strongly affected by noise. However, signals often arise at macroscopic scales integrating the effect of many neurons into a reliable pattern of activity. In order to study such large neuronal assemblies, one is often led to derive mean-field limits summarizing the effect of the interaction of a large number of neurons into an effective signal. Classical mean-field approaches consider the evolution of a deterministic variable, the mean activity, thus neglecting the stochastic nature of neural behavior. In this article, we build upon two recent approaches that include correlations and higher order moments in mean-field equations, and study how these stochastic effects influence the solutions of the mean-field equations, both in the limit of an infinite number of neurons and for large yet finite networks. We introduce a new model, the infinite model, which arises from both equations by a rescaling of the variables and, which is invertible for finite-size networks, and hence, provides equivalent equations to those previously derived models. The study of this model allows us to understand qualitative behavior of such large-scale networks. We show that, though the solutions of the deterministic mean-field equation constitute uncorrelated solutions of the new mean-field equations, the stability properties of limit cycles are modified by the presence of correlations, and additional non-trivial behaviors including periodic orbits appear when there were none in the mean field. The origin of all these behaviors is then explored in finite-size networks where interesting mesoscopic scale effects appear. This study leads us to show that the infinite-size system appears as a singular limit of the network equations, and for any finite network, the system will differ from the infinite system

Characterization of Peeling-Ballooning Stability Limits on the Pedestal

This report describes the Characterization of Peeling-Ballooning Stability Limits on the Pedestal