Anti-PF4 immunothrombosis without proximate heparin or adenovirus vector vaccine exposure.

ABSTRACT: Platelet-activating anti-platelet factor 4 (PF4)/heparin antibodies and anti-PF4 antibodies cause heparin-induced thrombocytopenia (HIT) and vaccine-induced immune thrombocytopenia and thrombosis (VITT), respectively. Diagnostic and treatment considerations differ somewhat between HIT and VITT. We identified patients with thrombocytopenia and thrombosis without proximate heparin exposure or adenovirus-based vaccination who tested strongly positive by PF4/polyanion enzyme-immunoassays and negative/weakly positive by heparin-induced platelet activation (HIPA) test but strongly positive by PF4-induced platelet activation (PIPA) test (ie, VITT-like profile). We tested these patients by a standard chemiluminescence assay that detects anti-PF4/heparin antibodies found in HIT (HemosIL AcuStar HIT-IgG(PF4-H)) as well as a novel chemiluminescence assay for anti-PF4 antibodies found in VITT. Representative control sera included an exploratory anti-PF4 antibody-positive but HIPA-negative/weak cohort obtained before 2020 (n = 188). We identified 9 patients with a clinical-pathological profile of a VITT-like disorder in the absence of proximate heparin or vaccination, with a high frequency of stroke (arterial, n = 3; cerebral venous sinus thrombosis, n = 4), thrombocytopenia (median platelet count nadir, 49 × 109/L), and hypercoagulability (greatly elevated D-dimer levels). VITT-like serological features included strong reactivity by PIPA (aggregation <10 minutes in 9/9 sera) and positive testing in the novel anti-PF4 chemiluminescence assay (3/9 also tested positive in the anti-PF4/heparin chemiluminescence assay). Our exploratory cohort identified 13 additional patient sera obtained before 2020 with VITT-like anti-PF4 antibodies. Platelet-activating VITT-like anti-PF4 antibodies should be considered in patients with thrombocytopenia, thrombosis, and very high D-dimer levels, even without a proximate exposure to heparin or adenovirus vector vaccines.

The Attitude towards Polypills Questionnaire (APPQ): a phase I-III development and validation study in patients with cerebrovascular disease.

BACKGROUND AND PURPOSE: The polypill approach has been proposed to reduce patients' pill burden, increase medication adherence and lower stroke incidence. However, little is known about patients' attitudes towards polypills for cerebrovascular medication. METHODS: Based on the European Organization for Research and Treatment of Cancer Quality of Life Group questionnaire development guidelines, a questionnaire to measure patients' attitudes towards polypills for the secondary prevention of stroke (phase I-III) was developed. In phase I, issues were generated via literature review and interviews with patients and healthcare professionals. The issues were operationalized into items in phase II. In phase III the questionnaire was validated in a large single-centre sample, and test-retest and internal validity were evaluated. RESULTS: In phase I, 34 relevant issues were identified through literature search and interviews. Pre-testing the questionnaire indicated high applicability and comprehensibility. The final Attitudes towards Polypills Questionnaire was tested in N = 260 patients and showed a two-factor structure. The factors were labelled 'concerns' and 'benefits'. The scales showed acceptable and good internal validity (concerns, Cronbach's α = 0.85; benefits, α = 0.93), but the scales' test-retest validity was ambiguous. On a 0 to 3 rating scale, concerns were rated lower than benefits (mean 1.07, SD 0.69 vs. mean 1.87, SD 0.89). CONCLUSIONS: The Attitudes towards Polypills Questionnaire showed high comprehensibility and content validity to assess German language patients' attitudes towards a polypill medication. Our data and questionnaire may aid the implementation of polypill treatments in clinical practice and can be used in the design of future clinical trials on polypill therapy. Further validation of the questionnaire is advised.

The dimension of preventable stroke in a large representative patient cohort.

OBJECTIVE: To analyze the frequency of inadequately treated risk factors in a large representative cohort of patients with acute ischemic stroke or TIA and to estimate the proportion of events potentially avertable by guideline-compliant preventive therapy compared to the status quo. METHODS: A total of 1,730 patients from the Poststroke Disease Management STROKE-CARD trial (NCT02156778) were recruited between 2014 and 2017. We focused on 8 risk conditions amenable to drug therapy and 3 lifestyle risk behaviors and assessed pre-event risk factor control in retrospect. RESULTS: The proportion of patients with at least 1 inadequately treated risk condition was 79.5% (95% confidence interval [CI] 77.6%-81.4%) and increased to 95.1% (95% CI 94.1%-96.1%) upon consideration of the lifestyle risk behaviors. Risk factor control was worse in patients with recurrent vs first-ever events (p < 0.001), men vs women (p = 0.003), and patients ≤75 vs >75 years of age (p < 0.001). The estimated degree of stroke preventability ranged from 0.4% (95% CI 0.2%-0.6%) to 13.7% (95% CI 12.2%-15.2%) for the individual risk factors. Adequate control of the 5 most relevant risk factors combined (hypertension, hypercholesterolemia, atrial fibrillation, smoking, and overweight) would have averted ≈1 of 2 events or 1 in 4 with a highly conservative computation approach. CONCLUSIONS: Our study confirms the existence of a considerable gap between risk factor control recommended by guidelines and real-world stroke prevention. Our study intends to increase awareness among physicians about stroke preventability and provides a quantitative basis for the emerging discussion on how to best tackle this challenge.

The Volume of Ischemic Brain Predicts Poor Outcome in Patients with Surgically Treated Malignant Stroke.

BACKGROUND: Malignant middle cerebral artery stroke is a life-threatening condition. The outcomes of surgical treatments have presented strong evidence in favor of decompressive hemicraniectomy (DHC). A significant subpopulation of patients still experience very poor outcomes. In particular, indication for DHC is based on few objective parameters to facilitate decision making. We hypothesized that larger ischemic brain volume would have a large impact on the outcome. METHODS: A cohort study of 34 patients undergoing DHC was performed using a volumetric analysis of infarction volume (measured preoperatively and again on postoperative day [POD] 1 and POD 3). Outcomes were assessed using the modified Rankin Scale (mRS), and a favorable outcome was defined as modified Rankin Scale score ≤3. RESULTS: Median age of patients was 53.5 years (range, 25-72 years), the median time from onset of first symptoms to surgical intervention was 38 hours (range, 10-150 hours), and male-to-female ratio was 2:1. The median ischemic volume was 250 cm3 preoperatively, 315 cm3 on POD1, and 349 cm3 on POD3. Modified Rankin Scale score ≤3 after 6 months was attained in 7 (20%) patients. Within the first 24 hours after DHC, ischemic volume increased significantly (P = 0.0003) and was associated with a worse outcome (P < 0.0001) after exceeding a cutoff volume of 300 cm3. CONCLUSIONS: Volumetric analysis of infarction can predict the outcome of patients. DHC should be reserved for patients with prognosticated good outcome, which was observed only in patients with a volume <301 cm3.

Chemical and enzymatic characterization of recombinant rabbit muscle pyruvate kinase.

The stepwise synthesis of thymidine triphosphate (TTP) requires a kinase for phosphorylation in the last step. Because pyruvate kinase (PK) using phosphoenolpyruvate (PEP) as substrate can regenerate adenosine triphosphate and phosphorylate thymidine diphosphate as well, we chose this enzyme for the synthesis of TTP via an enzymatic cascade reaction. The metalloenzyme PK shows pronounced promiscuity and therefore fits well to the conditions of this reaction. PK commonly used today is isolated from rabbit muscle. We cloned and expressed the respective open reading frame in Escherichia coli, purified, and characterized the His-tagged recombinant enzyme. The enzyme has an activity optimum at 37°C and in the pH range from 7.4 to 7.8. K(M) constants conformed well with the isolated native enzyme for adenosine diphosphate (ADP) to 0.37±0.02 mM and for PEP to 0.07±0.01 mM. The recombinant enzyme shows the following range in its substrate specificity: ADP>dADP>dGDP>dCDP>thymidine diphosphate (TDP). It allows the phosphorylation of TDP to TTP in high yield (up to 95%). The metal ions Mg(2+) and K(+) are necessary for full enzymatic activity. The addition of transition metal ions such as Mn(2+), Cu(2+), Co(2+), and Ni(2+) reduces activity. Storage of the enzyme at -20°C retains full activity.

Ab initio simulations of desorption and reactivity of glycine at a water-pyrite interface at "iron-sulfur world" prebiotic conditions.

Glycine at the interface of a pyrite surface (001) FeS2, and bulk water at high pressure and temperature conditions relevant to the "iron-sulfur world" scenario of the origin of life is investigated by theoretical means. Car-Parrinello molecular dynamics is used in order to study the desorption process of the zwitterionic form of this amino acid using two different adsorption modes, where either only one or both oxygens of the carboxylate group are anchored to surface iron atoms. It is found that the formation of stabilizing hydrogen bonds plays a key role in the detachment process, leading to longer retention times for the bidentate adsorption mode. In addition, the chemical reactivity of this heterogeneous system is probed by calculating the Fukui functions as site-specific reactivity indices. The most prominent targets for both nucleophilic and electrophilic reactions to occur are surface atoms, whereas the reactivity of glycine is only slightly affected upon anchoring.