Fe-implanted ZnO: Magnetic precipitates versus dilution

Nowadays ferromagnetism is often found in potential diluted magnetic semiconductor systems. However, many authors argue that the observed ferromagnetism stems from ferromagnetic precipitates or spinodal decomposition rather than from carrier mediated magnetic impurities, as required for a diluted magnetic semiconductor. In the present paper we answer this question for Fe-implanted ZnO single crystals comprehensively. Different implantation fluences and temperatures and post-implantation annealing temperatures have been chosen in order to evaluate the structural and magnetic properties over a wide range of parameters. Three different regimes with respect to the Fe concentration and the process temperature are found: 1) Disperse Fe$^{2+}$ and Fe$^{3+}$ at low Fe concentrations and low processing temperatures, 2) FeZn$_2$O$_4$ at very high processing temperatures and 3) an intermediate regime with a co-existence of metallic Fe (Fe$^0$) and ionic Fe (Fe$^{2+}$ and Fe$^{3+}$). Ferromagnetism is only observed in the latter two cases, where inverted ZnFe$_2$O$_4$ and $\alpha$-Fe nanocrystals are the origin of the observed ferromagnetic behavior, respectively. The ionic Fe in the last case could contribute to a carrier mediated coupling. However, their separation is too large to couple ferromagnetically due to the lack of p-type carrier. For comparison investigations of Fe-implanted epitaxial ZnO thin films are presented.Comment: 14 pages, 17 figure

Etiology, 3-Month Functional Outcome and Recurrent Events in Non-Traumatic Intracerebral Hemorrhage.

BACKGROUND AND PURPOSE Knowledge about different etiologies of non-traumatic intracerebral hemorrhage (ICH) and their outcomes is scarce. METHODS We assessed prevalence of pre-specified ICH etiologies and their association with outcomes in consecutive ICH patients enrolled in the prospective Swiss Stroke Registry (2014 to 2019). RESULTS We included 2,650 patients (mean±standard deviation age 72±14 years, 46.5% female, median National Institutes of Health Stroke Scale 8 [interquartile range, 3 to 15]). Etiology was as follows: hypertension, 1,238 (46.7%); unknown, 566 (21.4%); antithrombotic therapy, 227 (8.6%); cerebral amyloid angiopathy (CAA), 217 (8.2%); macrovascular cause, 128 (4.8%); other determined etiology, 274 patients (10.3%). At 3 months, 880 patients (33.2%) were functionally independent and 664 had died (25.1%). ICH due to hypertension had a higher odds of functional independence (adjusted odds ratio [aOR], 1.33; 95% confidence interval [CI], 1.00 to 1.77; P=0.05) and lower mortality (aOR, 0.64; 95% CI, 0.47 to 0.86; P=0.003). ICH due to antithrombotic therapy had higher mortality (aOR, 1.62; 95% CI, 1.01 to 2.61; P=0.045). Within 3 months, 4.2% of patients had cerebrovascular events. The rate of ischemic stroke was higher than that of recurrent ICH in all etiologies but CAA and unknown etiology. CAA had high odds of recurrent ICH (aOR, 3.38; 95% CI, 1.48 to 7.69; P=0.004) while the odds was lower in ICH due to hypertension (aOR, 0.42; 95% CI, 0.19 to 0.93; P=0.031). CONCLUSIONS Although hypertension is the leading etiology of ICH, other etiologies are frequent. One-third of ICH patients are functionally independent at 3 months. Except for patients with presumed CAA, the risk of ischemic stroke within 3 months of ICH was higher than the risk of recurrent hemorrhage

Absolute risk and predictors of the growth of acute spontaneous intracerebral haemorrhage: a systematic review and meta-analysis of individual patient data.

Background Intracerebral haemorrhage growth is associated with poor clinical outcome and is a therapeutic target for improving outcome. We aimed to determine the absolute risk and predictors of intracerebral haemorrhage growth, develop and validate prediction models, and evaluate the added value of CT angiography. Methods In a systematic review of OVID MEDLINE—with additional hand-searching of relevant studies' bibliographies— from Jan 1, 1970, to Dec 31, 2015, we identified observational cohorts and randomised trials with repeat scanning protocols that included at least ten patients with acute intracerebral haemorrhage. We sought individual patient-level data from corresponding authors for patients aged 18 years or older with data available from brain imaging initially done 0·5–24 h and repeated fewer than 6 days after symptom onset, who had baseline intracerebral haemorrhage volume of less than 150 mL, and did not undergo acute treatment that might reduce intracerebral haemorrhage volume. We estimated the absolute risk and predictors of the primary outcome of intracerebral haemorrhage growth (defined as >6 mL increase in intracerebral haemorrhage volume on repeat imaging) using multivariable logistic regression models in development and validation cohorts in four subgroups of patients, using a hierarchical approach: patients not taking anticoagulant therapy at intracerebral haemorrhage onset (who constituted the largest subgroup), patients taking anticoagulant therapy at intracerebral haemorrhage onset, patients from cohorts that included at least some patients taking anticoagulant therapy at intracerebral haemorrhage onset, and patients for whom both information about anticoagulant therapy at intracerebral haemorrhage onset and spot sign on acute CT angiography were known. Findings Of 4191 studies identified, 77 were eligible for inclusion. Overall, 36 (47%) cohorts provided data on 5435 eligible patients. 5076 of these patients were not taking anticoagulant therapy at symptom onset (median age 67 years, IQR 56–76), of whom 1009 (20%) had intracerebral haemorrhage growth. Multivariable models of patients with data on antiplatelet therapy use, data on anticoagulant therapy use, and assessment of CT angiography spot sign at symptom onset showed that time from symptom onset to baseline imaging (odds ratio 0·50, 95% CI 0·36–0·70; p<0·0001), intracerebral haemorrhage volume on baseline imaging (7·18, 4·46–11·60; p<0·0001), antiplatelet use (1·68, 1·06–2·66; p=0·026), and anticoagulant use (3·48, 1·96–6·16; p<0·0001) were independent predictors of intracerebral haemorrhage growth (C-index 0·78, 95% CI 0·75–0·82). Addition of CT angiography spot sign (odds ratio 4·46, 95% CI 2·95–6·75; p<0·0001) to the model increased the C-index by 0·05 (95% CI 0·03–0·07). Interpretation In this large patient-level meta-analysis, models using four or five predictors had acceptable to good discrimination. These models could inform the location and frequency of observations on patients in clinical practice, explain treatment effects in prior randomised trials, and guide the design of future trials

Inflammation, edema, hematoma and etiology - a rectangular relationship?

It was with great interest that we read the publication by Iglesias-Rey et al. [1], who found an association of elevated body temperature with perihemorrhagic edema (PHE) evolution exclusively in hypertension-related intracerebral hemorrhage (ICH). In accordance with pathophysiologic findings, others found an independent association of PHE evolution with inflammatory parameters including fever in ICH without further etiological differentiation [2,3]. Etiological classification of ICH may be challenging. Classifying patients with several identified etiological factors as unknown may pose possible bias. Identifying cerebral amyloid angiopathy (CAA)related ICH may require specific criteria and possibly further diagnostic testing [4,5]. A detailed description would be helpful. Furthermore, a larger sample size may be necessary to detect mechanisms related to PHE evolution in subgroups of ICH patients (e.g. CAA-related) due to the complex pathophysiological processes associated with PHE [2,3,6]. Here, ICH volume in particular and related measures are considered to be a major factor contributing to PHE evolution [6,7]. Thus, it is important to adjust analyses correlating PHE with other variables for ICH volume to assess independent associations. Delineation of PHE may be difficult on computed tomography scans. Although volumetric assessments using the ABC/2 formula may be considered when analysing hematoma volumes [8], validated algorithms are recommended in PHE assessment [9,10]. Although increasing evidence supports the association of inflammation and temperature with PHE evolution, further research is required to elucidate the complex interaction between inflammation, edema, hematoma and etiology

Prognostic significance of third ventricle blood volume in intracerebral haemorrhage with severe ventricular involvement

Background and purpose: Intraventricular haemorrhage (IVH) is an independent predictor of poor outcome in spontaneous intracerebral haemorrhage (ICH). Larger IVH volume and increasing number of affected ventricles have been associated with worse prognosis, however, little is known about the prognostic value of blood volume in the different parts of the ventricular system. Therefore, the correlation of IVH volume in the third, fourth and lateral ventricles with outcome in patients with ICH and severe IVH, treated with intraventricular fibrinolysis (IVF), was investigated. Methods: Patients with ICH <40 ml, severe IVH and acute hydrocephalus were treated with IVF. The course of IVH volume for each ventricle was measured by CT based volumetry. Outcome at 90 days was assessed by a telephone follow-up survey and correlated with initial IVH volume. Results: 50 patients aged 62.5±10.3 years with spontaneous ICH (12.5±10.8 ml) and severe IVH (33.5±25 ml) were included. Clearance of the third and fourth ventricle from blood occurred after 3±1.9 days. Initial IVH volume in the third ventricle (3.8±3.3 ml) was predictive for poor outcome (OR 2.6 per ml, p=0.02). Correlation between larger IVH volume in the fourth ventricle and poor outcome showed a trend towards significance (p=0.07). Total IVH volume and lateral ventricle IVH volume were not correlated with outcome. Conclusion: Despite rapid clot removal, initial IVH volume in the third ventricle was a strong and independent negative predictor. This is possibly explained by irreversible damage of brainstem structures by the initial mass effect of IVH

Efficacy and safety of combined intraventricular fibrinolysis with lumbar drainage for prevention of permanent shunt dependency after intracerebral hemorrhage with severe ventricular involvement: A randomized trial and individual patient data meta-analysis.

OBJECTIVE Intraventricular hemorrhage (IVH) is a negative prognostic factor in intracerebral hemorrhage (ICH) and is associated with permanent shunt dependency in a substantial proportion of patients post-ICH. IVH treatment by intraventricular fibrinolysis (IVF) was recently linked to reduced mortality rates in the CLEAR III study and IVF represents a safe and effective strategy to hasten clot resolution that may reduce shunt rates. Additionally, promising results from observational studies reported reductions in shunt dependency for a combined treatment approach of IVF plus lumbar drains (LDs). The present randomized, controlled trial investigated efficacy and safety of a combined strategy-IVF plus LD versus IVF alone-on shunt dependency in patients with ICH and severe IVH. METHODS This randomized, open-label, parallel-group study included patients aged 18 to 85 years, prehospital modified Rankin Scale ≤3, ICH volume < 60ml, Glasgow Coma Scale of <9, and severe IVH with tamponade of the third and fourth ventricles requiring placement of external ventricular drainage (EVD). Over a 3-year recruitment period, patients were allocated to either standard treatment (control group receiving IVF consisting of 1mg of recombinant human tissue plasminogen activator every 8 hours until clot clearance of third and fourth ventricles) or a combined treatment approach of IVF and-upon clot clearance of third and fourth ventricles-subsequent placement of an LD for drainage of cerebrospinal fluid (CSF; intervention group). The primary endpoint consisted of permanent shunt placement indicated after a total of three unsuccessful EVD clamping attempts or need for CSF drainage longer than 14 days in both groups. Secondary endpoints included IVF- and LD-related safety, such as bleeding or infections, and functional outcome at 90 and 180 days. Conducted endpoint analyses used individual patient data meta-analyses. The study was registered at clinicaltrials.gov (NCT01041950). RESULTS The trial was stopped upon predefined interim analysis after 30 patients because of significant efficacy of tested intervention. The primary endpoint was analyzed without dropouts and was reached in 43% (7 of 16) of the control group versus 0% (0 of 14) of the intervention group (p = 0.007). Meta-analyses were based on overall 97 patients, 45 patients receiving IVF plus LD versus 42 with IVF only. Meta-analyses on shunt dependency showed an absolute risk reduction of 24% for the intervention (LD, 2.2% [1 of 45] vs no-LD, 26.2% [11 of 42]; odds ratio [OR] = 0.062; confidence interval [CI], 0.011-0.361; p = 0.002). Secondary endpoints did not show significant differences for CSF infections (OR = 0.869;CI, 0.445-1.695; p = 0.680) and functional outcome at 90 days (OR = 0.478; CI, 0.190-1.201; p = 0.116), yet bleeding complications were significantly reduced in favor of the intervention (OR = 0.401; CI, 0.302-0.532; p < 0.001). INTERPRETATION The present trial and individual patient data meta-analyses provide evidence that, in patients with severe IVH, as compared to IVF alone, a combined approach of IVF plus LD treatment is feasible and safe and significantly reduces rates of permanent shunt dependency for aresorptive hydrocephalus post-ICH. ANN NEUROL 2017;81:93-103

Peak perihemorrhagic edema correlates with functional outcome in intracerebral hemorrhage.

OBJECTIVE To evaluate the association of perihemorrhagic edema (PHE) evolution and peak edema extent with day 90 functional outcome in patients with intracerebral hemorrhage (ICH) and identify pathophysiologic factors influencing edema evolution. METHODS This retrospective cohort study included patients with spontaneous supratentorial ICH between January 2006 and January 2014. ICH and PHE volumes were studied using a validated semiautomatic volumetric algorithm. Multivariable logistic regression and propensity score matching (PSM) accounting for age, ICH volume, and location were used for assessing measures associated with functional outcome and PHE evolution. Clinical outcome on day 90 was assessed using the modified Rankin Scale (0-3 = favorable, 4-6 = poor). RESULTS A total of 292 patients were included. Median age was 70 years (interquartile range [IQR] 62-78), median ICH volume on admission 17.7 mL (IQR 7.9-40.2). Besides established factors for functional outcome, i.e., ICH volume and location, age, intraventricular hemorrhage, and NIH Stroke Scale score on admission, multivariable logistic regression revealed peak PHE volume (odds ratio [OR] 0.984 [95% confidence interval (CI) 0.973-0.994]) as an independent predictor of day 90 outcome. Peak PHE volume was independently associated with initial PHE increase up to day 3 (OR 1.060 [95% CI 1.018-1.103]) and neutrophil to lymphocyte ratio on day 6 (OR 1.236 [95% CI 1.034-1.477; PSM cohort, n = 124]). Initial PHE increase (PSM cohort, n = 224) was independently related to hematoma expansion (OR 3.647 [95% CI 1.533-8.679]) and fever burden on days 2-3 (OR 1.456 [95% CI 1.103-1.920]). CONCLUSION Our findings suggest that peak PHE volume represents an independent predictor of functional outcome after ICH. Inflammatory processes and hematoma expansion seem to be involved in PHE evolution and may represent important treatment targets

Severity assessment in maximally treated ICH patients: The max-ICH score.

OBJECTIVE As common prognostication models in intracerebral hemorrhage (ICH) are developed variably including patients with early (<24 hours) care limitations (ECL), we investigated its interaction with prognostication in maximally treated patients and sought to provide a new unbiased severity assessment tool. METHODS This observational cohort study analyzed consecutive ICH patients (n = 583) from a prospective registry over 5 years. We characterized the influence of ECL on overall outcome by propensity score matching and on conventional prognostication using receiver operating characteristic analyses. We established the max-ICH score based on independent predictors of 12-month functional outcome in maximally treated patients and compared it to existing models. RESULTS Prevalence of ECL was 19.2% (n = 112/583) and all of these patients died. Yet propensity score matching displayed that 50.7% (n = 35/69) theoretically could have survived, with 18.8% (n = 13/69) possibly reaching favorable outcome (modified Rankin Scale score 0-3). Conventional prognostication seemed to be confounded by ECL, documented by a decreased predictive validity (area under the curve [AUC] 0.67, confidence interval [CI] 0.61-0.73 vs AUC 0.80, CI 0.76-0.83; p < 0.01), overestimating poor outcome (mortality by 44.8%, unfavorable outcome by 10.1%) in maximally treated patients. In these patients, the novel max-ICH score (0-10) integrates strength-adjusted predictors, i.e., NIH Stroke Scale score, age, intraventricular hemorrhage, anticoagulation, and ICH volume (lobar and nonlobar), demonstrating improved predictive accuracy for functional outcome (12 months: AUC 0.81, CI 0.77-0.85; p < 0.01). The max-ICH score may more accurately delineate potentials of aggressive care, showing favorable outcome in 45.4% (n = 214/471) and a long-term mortality rate of only 30.1% (n = 142/471). CONCLUSIONS Care limitations significantly influenced the validity of common prognostication models resulting in overestimation of poor outcome. The max-ICH score demonstrated increased predictive validity with minimized confounding by care limitations, making it a useful tool for severity assessment in ICH patients