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Severe acute respiratory syndrome coronavirus type 2 (SARS‐CoV‐2) infection can lead to life‐threatening clinical manifestations. Patients with cardiovascular disease (CVD) are at higher risk for severe courses of COVID‐19. So far, however, there are hardly any strategies for predicting the course of SARS‐CoV‐2 infection in CVD patients at hospital admission. Thus, we investigated whether this prediction is achievable by prospectively analysing the blood immunophenotype of 94 nonvaccinated participants, including uninfected and acutely SARS‐CoV‐2‐infected CVD patients and healthy donors, using a 36‐colour spectral flow cytometry panel. Unsupervised data analysis revealed little differences between healthy donors and CVD patients, whereas the distribution of the cell populations changed dramatically in SARS‐CoV‐2‐infected CVD patients. The latter had more mature NK cells, activated monocyte subsets, central memory CD4+ T cells, and plasmablasts but fewer dendritic cells, CD16+ monocytes, innate lymphoid cells, and CD8+ T‐cell subsets. Moreover, we identified an immune signature characterised by CD161+ T cells, intermediate effector CD8+ T cells, and natural killer T (NKT) cells that is predictive for CVD patients with a severe course of COVID‐19. Thus, intensified immunophenotype analyses can help identify patients at risk of severe COVID‐19 at hospital admission, improving clinical outcomes through specific treatment. [ABSTRACT FROM AUTHOR]

Background: Risk stratification for transcatheter procedures in patients with severe mitral regurgitation is challenging. Deceleration capacity (DC) has already proven to be a reliable risk predictor in patients undergoing transcatheter aortic valve implantation. We hypothesized, that DC provides prognostic value in patients undergoing transcatheter edge‐to‐edge mitral valve repair (TEER). Methods: We retrospectively analyzed electrocardiogram signals from 106 patients undergoing TEER at the University Hospital of Tübingen. All patients received continuous heart‐rate monitoring to assess DC following the procedure. One‐year all‐cause mortality was defined as the primary end point. Results: Sixteen patients (15.1%) died within 1 year. The DC in nonsurvivors was significantly reduced compared to survivors (5.1 ± 3.0 vs. 3.0 ± 1.6 ms, p = 0.002). A higher EuroSCORE II and impaired left ventricular function were furthermore associated with poor outcome. In Cox regression analyses, a DC < 4.5 ms was found a strong predictor of 1‐year mortality (hazard ratio: 0.10, 95% confidence interval: 0.13–0.79, p = 0.029). Finally, a significant negative correlation was found between DC and residual mitral regurgitation after TEER (r = −0.41, p < 0.001). Conclusion: In patients with severe mitral regurgitation undergoing TEER, DC may serve as a new predictor of follow‐up mortality. [ABSTRACT FROM AUTHOR]

Background: Cardiovascular risk factors and comorbidities are highly prevalent among COVID‐19 patients and are associated with worse outcomes. Hypothesis: We therefore investigated if established cardiovascular risk assessment models could efficiently predict adverse outcomes in COVID‐19. Furthermore, we aimed to generate novel risk scores including various cardiovascular parameters for prediction of short‐ and midterm outcomes in COVID‐19. Methods: We included 441 consecutive patients diagnosed with SARS‐CoV‐2 infection. Patients were followed‐up for 30 days after the hospital admission for all‐cause mortality (ACM), venous/arterial thromboembolism, and mechanical ventilation. We further followed up the patients for post‐COVID‐19 syndrome for 6 months and occurrence of myocarditis, heart failure, acute coronary syndrome (ACS), and rhythm events in a 12‐month follow‐up. Discrimination performance of DAPT, GRACE 2.0, PARIS‐CTE, PREDICT‐STABLE, CHA2‐DS2‐VASc, HAS‐BLED, PARIS‐MB, PRECISE‐DAPT scores for selected endpoints was evaluated by ROC‐analysis. Results: Out of established risk assessment models, GRACE 2.0 score performed best in predicting combined endpoint and ACM. Risk assessment models including age, cardiovascular risk factors, echocardiographic parameters, and biomarkers, were generated and could successfully predict the combined endpoint, ACM, venous/arterial thromboembolism, need for mechanical ventilation, myocarditis, ACS, heart failure, and rhythm events. Prediction of post‐COVID‐19 syndrome was poor. Conclusion: Risk assessment models including age, laboratory parameters, cardiovascular risk factors, and echocardiographic parameters showed good discrimination performance for adverse short‐ and midterm outcomes in COVID‐19 and outweighed discrimination performance of established cardiovascular risk assessment models. [ABSTRACT FROM AUTHOR]

Localized delivery of diagnostic/therapeutic agents to cerebral aneurysms, lesions in brain arteries, may offer a new treatment paradigm. Since aneurysm rupture leading to subarachnoid hemorrhage is a devastating medical emergency with high mortality, the ability to noninvasively diagnose high‐risk aneurysms is of paramount importance. Moreover, treatment of unruptured aneurysms with invasive surgery or minimally invasive neurointerventional surgery poses relatively high risk and there is presently no medical treatment of aneurysms. Here, leveraging the endogenous biophysical properties of brain aneurysms, we develop particulate carriers designed to localize in aneurysm low‐shear flows as well as to adhere to a diseased vessel wall, a known characteristic of high‐risk aneurysms. We first show, in an in vitro model, flow guided targeting to aneurysms using micron‐sized (2 μm) particles, that exhibited enhanced targeting (>7 folds) to the aneurysm cavity while smaller nanoparticles (200 nm) showed no preferable accumulation. We then functionalize the microparticles with glycoprotein VI (GPVI), the main platelet receptor for collagen under low‐medium shear, and study their targeting in an in vitro reconstructed patient‐specific aneurysm that contained a disrupted endothelium at the cavity. Results in this model showed that GPVI microparticles localize at the injured aneurysm an order of magnitude (>9 folds) more than control particles. Finally, effective targeting to aneurysm sites was also demonstrated in an in vivo rabbit aneurysm model with a disrupted endothelium. Altogether, the presented biophysical strategy for targeted delivery may offer new treatment opportunities for cerebral aneurysms. [ABSTRACT FROM AUTHOR]

Background: Gremlin‐1 is a cystine knot protein and is expressed in organs developing fibrosis. Transient ischaemia leads to myocardial fibrosis, a major determinant of impaired myocardial function. Materials and methods: Expression of Gremlin‐1 was investigated in infarcted myocardium by real‐time PCR, Western blot analysis, histological and immunohistochemistry staining. We further elaborated the colocalization of Gremlin‐1 and TGF‐β proteins by confocal microscopy and co‐immunoprecipitation experiments. The interaction between Gremlin‐1 and TGF‐β was analysed by photon correlation spectroscopy. Gremlin‐1 modulation of the TGF‐β‐dependent collagen I synthesis in fibroblasts was investigated using ELISA and immunohistochemistry experiments. The effect of prolonged administration of recombinant Gremlin‐1 on myocardial function following ischaemia/reperfusion was accessed by echocardiography and immunohistochemistry. Results: Gremlin‐1 is expressed in myocardial tissue and infiltrating cells after transient myocardial ischaemia (P <.05). Gremlin‐1 colocalizes with the pro‐fibrotic cytokine transforming growth factor‐β (TGF‐β) expressed in fibroblasts and inflammatory cell infiltrates (P <.05). Gremlin‐1 reduces TGF‐β‐induced collagen production of myocardial fibroblasts by approximately 20% (P <.05). We found that Gremlin‐1 binds with high affinity to TGF‐β (KD = 54 nmol/L) as evidenced by photon correlation spectroscopy and co‐immunoprecipitation. intravenous administration of mGremlin‐1‐Fc, but not of equivalent amount of Fc control, significantly reduced infarct size by approximately 20%. In the mGremlin‐1‐Fc group, infarct area was reduced by up to 30% in comparison with mice treated with Fc control (I/LV: 4.8 ± 1.2% vs 6.0 ± 1.2% P <.05; I/AaR: 15.2 ± 1.5% vs 21.1 ± 5%, P <.05). Conclusions: The present data disclose Gremlin‐1 as an antagonist of TGF‐β and presume a role for Gremlin‐1/TGF‐β interaction in myocardial remodelling following myocardial ischaemia. [ABSTRACT FROM AUTHOR]

Antiplatelet response to clopidogrel shows wide variation, and poor response is correlated with adverse clinical outcomes. CYP2C19 loss‐of‐function alleles play an important role in this response, but account for only a small proportion of variability in response to clopidogrel. An aim of the International Clopidogrel Pharmacogenomics Consortium (ICPC) is to identify other genetic determinants of clopidogrel pharmacodynamics and clinical response. A genomewide association study (GWAS) was performed using DNA from 2,750 European ancestry individuals, using adenosine diphosphate‐induced platelet reactivity and major cardiovascular and cerebrovascular events as outcome parameters. GWAS for platelet reactivity revealed a strong signal for CYP2C19*2 (P value = 1.67e−33). After correction for CYP2C19*2 no other single‐nucleotide polymorphism reached genomewide significance. GWAS for a combined clinical end point of cardiovascular death, myocardial infarction, or stroke (5.0% event rate), or a combined end point of cardiovascular death or myocardial infarction (4.7% event rate) showed no significant results, although in coronary artery disease, percutaneous coronary intervention, and acute coronary syndrome subgroups, mutations in SCOS5P1, CDC42BPA, and CTRAC1 showed genomewide significance (lowest P values: 1.07e−09, 4.53e−08, and 2.60e−10, respectively). CYP2C19*2 is the strongest genetic determinant of on‐clopidogrel platelet reactivity. We identified three novel associations in clinical outcome subgroups, suggestive for each of these outcomes. [ABSTRACT FROM AUTHOR]

50%-60% of patients with chronic mesenteric ischemia suffer from concomitant cardiovascular disease. We therefore suggest an extensive diagnostic screening to detect coronary artery and peripheral arterial disease in these patients. [ABSTRACT FROM AUTHOR]

Introduction: The role of cryoballoon (CB) pulmonary vein isolation (PVI) for patients with persistent atrial fibrillation (AF) is controversial, since long‐term success can be poor. We performed left atrial voltage mapping before CB PVI and determined AF‐free survival depending on the extent of low‐voltage areas (LVAs). Methods and Results: We consecutively enrolled 60 patients with persistent AF (average age, 60.6 ± 12.9 years; CHA2DS 2 VASc score, 2.3 ± 1.6; and left atrial size 46.0 ± 5.2 mm) who were planned for CB PVI. Before ablation, we performed left atrial voltage mapping (Abbott EnSite Precision or Velocity). LVAs were defined if local bipolar signal amplitudes were less than 0.5 mV during sinus rhythm. Thirty‐seven patients did not show significant LVAs (<10%), while 12 patients had LVAs between 10% and 30% and 11 patients showed substantial LVAs greater than 30% of the left atrial area. CB PVI could be successfully performed in all patients. A 7‐day holter monitoring was obtained 3, 6, and 12 months after ablation. After a 12‐month follow‐up time, 83.8% of patients without LVAs (<10%) were free of atrial fibrillation, while 50.0% of patients with 10% to 30% LVAs and 9.1% of patients with LVAs more than 30% had stable sinus rhythm. The degree of atrial fibrosis correlated with the risk of AF recurrence. Conclusion: In patients with persistent AF undergoing CB PVI, the extent of left atrial LVAs predicts an AF‐free survival. CB PVI seems to be a highly effective treatment for patients with persistent AF without atrial fibrosis. [ABSTRACT FROM AUTHOR]

Summary: Superficial fungal infections of the skin, nails and hair are common with Trichophyton rubrum and Candida albicans being the main pathogens. Yet, in some patients, mycological cultures show growth of more than one fungal agent in the same anatomical region. This study analyses prevalence, frequency and fungal agents found in superficial fungal mixed infections and discusses consequences for diagnostics and treatment. Mycological data obtained between January 2006 and December 2015 from clinical specimens from a total cohort of 7733 patients with suspected fungal infections were retrospectively analysed. All specimens were cultured on Sabouraud's dextrose and dermatophyte agar. Patients were included in this study, if more than one fungal species developed in culture. Mixed infections account to 6% of all superficial fungal infections. In more than half of the cases, a combination of dermatophyte and yeast is found, mostly concerning foot lesions. Male patients between 60 and 80 year are most commonly affected (39% of mixed infections). Rare species are found in distinctly higher percentages in fungal mixed infections than in general. Sampling of all regions of suspected fungal infection and cultural proof are essential for purposeful systemic therapy. Delayed treatment of fungal infections may enable secondary co‐infection by species usually considered little pathogenic. [ABSTRACT FROM AUTHOR]

Abstract: Aim: The aim of this study is to analyse the prognostic value of complement anaphylatoxin receptors in patients with non‐ischaemic cardiomyopathy undergoing endomyocardial biopsy. Methods and results: In 102 patients (72.5% male patients, median age 54 years) with non‐ischaemic cardiomyopathy, myocardial expression of C3aR was assessed among other parameters. The primary study endpoint was a composite of death, heart transplantation, heart failure‐related re‐hospitalization, and deterioration of left ventricular ejection fraction within a mean follow‐up of 11.9 months. The number of cells, which stained positive for C3aR, was significantly increased in patients with inflammatory compared with non‐inflammatory cardiomyopathy (1.75 ± 0.31 cells in inflammatory cardiomyopathy vs. 0.94 ± 0.26 in non‐inflammatory cardiomyopathy, P = 0.049). Subsequently, positive expression for C3aR was judged based on a semi‐quantitative scoring system. Significantly, more patients with positive MHCII and CD68 expression showed an increased number of C3aR‐positive cells. C3aR expression based on this score was more pronounced in patients with human herpesvirus 6 viral genome detection. Kaplan–Meier curves illustrate that the C3aR‐negative group reached the primary endpoint significantly more often (mean follow‐up 11.9 months, log rank 5.963, P = 0.015). Lack of C3aR expression was a strong independent predictor for the primary endpoint in Cox regression analysis [hazard ratio 0.46 (0.26–0.82, P = 0.009)]. Conclusions: C3aR‐positive cells are found more often in patients with inflammatory cardiomyopathy. The relevance of C3aR‐positive cells in patients with non‐ischaemic cardiomyopathy should be further evaluated as potential predictors or modulators of adverse cardiac remodelling, the substrate of progressive heart failure. [ABSTRACT FROM AUTHOR]

Abstract: Gαi2, a heterotrimeric G‐protein subunit, regulates various cell functions including ion channel activity, cell differentiation, proliferation and apoptosis. Platelet‐expressed Gαi2 is decisive for the extent of tissue injury following ischemia/reperfusion. However, it is not known whether Gαi2 plays a role in the regulation of platelet apoptosis, which is characterized by caspase activation, cell shrinkage and cell membrane scrambling with phosphatidylserine (PS) translocation to the platelet surface. Stimulators of platelet apoptosis include thrombin and collagen‐related peptide (CoRP), which are further known to enhance degranulation and activation of αIIbβ3‐integrin and caspases. Using FACS analysis, we examined the impact of agonist treatment on activation and apoptosis in platelets drawn from mice lacking Gαi2 and their wild‐type (WT) littermates. As a result, treatment with either thrombin (0.01 U/mL) or CoRP (2 μg/mL or 5 μg/mL) significantly upregulated PS‐exposure and significantly decreased forward scatter, reflecting cell size, in both genotypes. Exposure to CoRP triggered a significant increase in active caspase 3, ceramide formation, surface P‐selectin, and αIIbβ3‐integrin activation. These molecular alterations were significantly less pronounced in Gαi2‐deficient platelets as compared to WT platelets. In conclusion, our data highlight a previously unreported role of Gαi2 signaling in governing platelet activation and apoptosis. [ABSTRACT FROM AUTHOR]

Purpose: To introduce a dual-contrast fast spin-echo (dcFSE) sequence for signal decay mapping of myocardial edema.Materials and Methods: After consultation with the Institutional Review Board, 22 acute myocardial infarction (MI) patients were examined with magnetic resonance imaging (MRI) at 1.5T 2 days after revascularization. Edema was evaluated in 16 myocardial segments with an exponential fit for signal decay time (SDT) in dcFSE mapping and T2 signal intensity ratio for single-contrast FSE. Myocardial viability was evaluated in late gadolinium enhancement (LGE). A control group of 10 volunteers was examined for edema imaging. SDT was compared in segment groups: 1) with LGE in MI, 2) penumbra, 3) remote from LGE, 4) controls. Groups 1/3 and 3/4 were tested on difference. Three phantoms providing similar T2 but different T1 relaxation times (low, intermediate, high) were examined with dcFSE and multicontrast spin echo sequence as a reference.Results: The SDT/T2 ratio for segment groups was 1) 82msec/1.7 in segments with LGE; 2) 65msec/1.6 for penumbra, 3) 62msec/1.7 for remote segments, and 4) 50msec/1.6 in controls. In dcFSE group 1/3 (P < 0.0001) and in group 3/4 (P = 0.0002) SDT was significantly different. In single-contrast FSE the T2 ratio was not significantly different for both tests: 1/3 P = 0.1889; 3/4 P = 0.8879. T2 -overestimation of dcFSE was 23% in low, 29% in intermediate, and 35% in highly T1 contaminated phantoms.Conclusion: dcFSE signal decay edema mapping is feasible in volunteers and patients. DcFSE SDT is superior to T2 ratio for detection of high-grade and diffuse myocardial edema. J. Magn. Reson. Imaging 2016;44:186-193. [ABSTRACT FROM AUTHOR]

Background and purpose: Recently, the CRYSTAL AF trial detected paroxysmal atrial fibrillation (AF) in 12.4% of patients after cryptogenic ischaemic stroke (IS) or cryptogenic transient ischaemic attack (TIA) by an insertable cardiac monitor (ICM) within 1 year of monitoring. Our aim was (i) to assess if an AF risk factor based pre-selection of ICM candidates would enhance the rate of AF detection and (ii) to determine AF risk factors with significant predictive value for AF detection. Methods: Seventy-five patients with cryptogenic IS/TIA were consecutively enrolled if at least one of the following AF risk factors was present: a CHA2DS2-VASc score ≥4, atrial runs, left atrium (LA) size >45 mm, left atrial appendage (LAA) flow ≤0.2 m/s, or spontaneous echo contrast in the LAA. The electrocardiographic and echocardiographic criteria were chosen as they have been repeatedly reported to predict AF; the same applies for four of the six items of the CHA2DS2-VASc score. The study end-point was the detection of one or more episodes of AF (≥2 min). Results: Seventy-four patients underwent implantation of an ICM; one patient had AF at the date of implantation. After 6 months, AF was detected in 21/75 patients (28%), after 12 months in 25/75 patients (33.3%). 92% of AF episodes were asymptomatic. LA size >45 mm and the presence of atrial runs were independently associated with AF detection [hazard ratio 3.6 (95% confidence interval 1.6-8.4), P = 0.002, and 2.7 (1.2-6.7), P = 0.023, respectively]. Conclusions: The detection rate of AF is one-third after 1 year if candidates for an ICM after cryptogenic IS/TIA are selected by AF risk factors. LA dilation and atrial runs independently predict AF. [ABSTRACT FROM AUTHOR]

Macrophage migration-inhibitory factor (MIF) is a pleiotropic cytokine with chemokine-like functions and is a mediator in numerous inflammatory conditions. Depending on the context, MIF signals through 1 or more of its receptors cluster of differentiation (CD)74, CXC-motif chemokine receptor (CXCR)2, and CXCR4. In addition, heteromeric receptor complexes have been identified. We characterized the atypical chemokine receptor CXCR7 as a novel receptor for MIF. MIF promoted human CXCR7 internalization up to 40%, peaking at 50-400 nM and 30 min, but CXCR7 internalization by MIF was not dependent on CXCR4. Yet, by coimmunoprecipitation, fluorescence microscopy, and a proximity ligation assay, CXCR7 was found to engage in MIF receptor complexes with CXCR4 and CD74, both after ectopic overexpression and in endogenous conditions in a human B-cell line. Receptor competition binding and coimmunoprecipitation studies combined with sulfo-SBED-biotin-transfer provided evidence for a direct interaction between MIF and CXCR7. Finally, we demonstrated MIF/CXCR7-mediated functional responses. Blockade of CXCR7 suppressed MIF-mediated ERK- and zeta-chain-associated protein kinase (ZAP)-70 activation (from 2.1- to 1.2-fold and from 2.5- to 1.6-fold, respectively) and fully abrogated primary murine B-cell chemotaxis triggered by MIF, but not by CXCL12. B cells from Cxcr7-/- mice exhibited an ablated transmigration response to MIF, indicating that CXCR7 is essential for MIF-promoted B-cell migration. Our findings provide biochemical and functional evidence that MIF is an alternative ligand of CXCR7 and suggest a functional role of the MIF-CXCR7 axis in B-lymphocyte migration. [ABSTRACT FROM AUTHOR]

Background Discontinuation of oral anticoagulation (OAC) after catheter ablation of atrial fibrillation (AF) is not recommended in patients with elevated CHADS2 scores. However, a low incidence of thromboembolic events is reported when OAC is stopped in these patients. We introduce an algorithm for discontinuation of OAC after ablation based on the AF burden documented by implantable cardiac monitors (ICM). Methods Sixty-five patients with CHADS2 scores 1-3 free from AF 3 months after ablation (AF ablation [n = 49] or ablation of possible AF triggers [n = 16]) were included. One day after implantation of the ICM, OAC was stopped. Patients performed a daily interrogation of the ICM which was programmed to alarm the patient if daily AF burden exceeded 1 hour. Study end point was the first recurrence of a daily AF burden ≥1 hour or a thromboembolic event, which both triggered reinitiation of OAC. Results During a follow-up time of 32 ± 12 months (126 patient-years), 41 of the 65 patients (63%) had an AF burden <1 h/day and were able to stay off OAC. Twenty-one patients (32%) had to reinitiate OAC due to an AF burden ≥1 hour and three patients due to other reasons. No stroke, transitory ischemic attack, or other thromboembolic event was observed during follow-up. Conclusions Rhythm monitoring by ICM in patients who have stopped OAC after catheter ablation of AF or ablation of possible AF triggers seems to be a safe and promising method to monitor for AF recurrence. Within 1.3 years after ablation, about two-thirds of patients were able to stay off OAC. [ABSTRACT FROM AUTHOR]

The serum- and glucocorticoid-inducible kinase 1 ( SGK1) is expressed in megakaryocytes and circulating platelets. In megakaryocytes, SGK1 activates transcription factor nuclear factor kappa-B ( NF- κB), which in turn stimulates expression of Orai1, a Ca2+ channel protein accomplishing store-operated Ca2+ enrty ( SOCE). SGK1 enhances SOCE and several Ca2+-sensitive platelet functions, including degranulation, integrin α IIb β3 activation, phosphatidylserine exposure, aggregation and thrombus formation. As shown in other cell types, stimulators of SGK1 expression include ischaemia, oxidative stress, hyperglycaemia, advanced glycation end products ( AGEs) and a variety of hormones such as glucocorticoids, mineralocorticoids, transforming growth factor beta ( TGF β), interleukin 6 ( IL-6), platelet-derived growth factor ( PDGF), thrombin and endothelin. Thus, SGK1-sensitive Ca2+ signalling may contribute to altered platelet function in several clinical conditions including inflammation, metabolic syndrome, diabetes mellitus and chronic renal failure. Nevertheless, further studies are needed defining the contribution of altered SGK1 expression and activity to physiology and pathophysiology of platelets. [ABSTRACT FROM AUTHOR]

Platelet-derived SDF-1α (CXCL12) mediates inflammatory and regenerative mechanisms. The present study characterizes the effect of SDF-1α ligation in platelets. SDF-1α (0-100 μM) dose and time dependently caused internalization of its receptor CXCR4 (28.9±1.6 vs. 16.1±1.9 in SDF-1α-treated platelets), coupled to the surface externalization of CXCR7 (65.5±8 vs. 162.8±27.6 following SDF-1α treatment), both in vitro and in vivo. This was inhibited in the presence of AMD3100 (100 μM), CXCR4 blocking and vesicular transport inhibitors (brefeldin A, 10 μM; rapamycin, 100 nM). SDF-1α/CXCR-4-mediated CXCR7 translocation was significantly reduced by inhibitors of ERK1/2-(U0126-10 μM) and cyclophilinA (CyPA)-(NIM811-10 μM) by 28 and 46%, respectively. Further, SDF-1α-induced downstream phosphorylation of Erk1/2 led to CyPA-dependent ubiquitination of CXCR7, which is essential for its surface translocation. CyPA-PPIase-activity inhibitor NIM-811, Erk1/2, and E1-ligase inhibitor-(PYR-41-25 μM) significantly abolished SDF-1α-driven CXCR7 ubiquitination and subsequent surface translocation. SDF-1α induced CXCR7 ubiquitination, and its surface exposure was observed in wild-type murine platelets, but not in CyPA-deficient platelets. SDF-1α/CXCR4-CyPA-dependent CXCR7 translocation and its subsequent ligation attenuated activation-induced apoptosis both in vitro and when administered in vivo. This antiapoptotic effect of SDF-1α was abrogated by blocking CXCR7, also significantly affected in Cypa-/- platelets. Thus, we decipher a novel mechanism, whereby SDF-1α regulates relative receptor availability in circulating platelets and exerts its prosurvival benefits. [ABSTRACT FROM AUTHOR]

Platelets are activated by increased cytsolic Ca2+ concentration ([Ca2+]i) following store-operated calcium entry (SOCE) accomplished by calcium release-activated calcium (CRAC) channel moiety Orail and its regulator STIM1. In other cells, Ca2+ transport is regulated by 1,25(OH) 2 vitamin D3 [1,25(OH) 2D3] 1,25(OH) 2D3 formation is inhibited by klotho and excessive in klotho-deficient mice (kl/kl). The prese study explored the effect of klotho deficiency o platelet Ca2+ signaling and activation. Platelets an megakaryocytes isolated from WT and kl/kl-mice we analyzed by RT-PCR, Western blotting, confocal microscopy, Fura-2-fluorescence, patch clamp, flow cytometry, aggregometry, and flow chamber. STIM1/Orail transcript and protein levels, SOCE, agonist-induce [Ca2+]i increase, activation-dependent degranulation, integrin αIIbβ3 activation and aggregation, and thrombus formation were significantly blunted in kl/kl platelets (by 27-90%). STIM1/Orail transcript and protein levels, as well as CRAC currents, were significantly reduced in kl/kl megakaryocytes (by 38-73%) 1,25(OH)2D3-treated WT megakaryocytes. Nuclear NF-ΚB subunit p50/p65 abundance was significant reduced in kl/kl-megakaryocytes (by 51-76%). Transfection with p50/p65 significantly increased STIM1 Orall transcript and protein levels in megakaryocytic MEG-01 cells (by 46-97%). Low-vitamin D diet (LVD of kl/kl mice normalized plasma 1,25(OH)2D3 concentration and function of platelets and megakaryocyte. Klotho deficiency inhibits platelet Ca2+ signaling and activation, an effect at least partially due to 1,25(OH)2D3-dependent down-regulation of NF-ΚB activity and STIM1/Orail expression in megakaryocytes. [ABSTRACT FROM AUTHOR]

Chorea-acanthocytosis (ChAc), a lethal disease caused by defective chorein, is characterized by neurodegeneration and erythrocyte acanthocytosis. The functional significance of chorein in other cell types remained ill-defined. The present study revealed chorein expression in blood platelets. As compared to platelets from healthy volunteers, platelets from patients with ChAc displayed a 47% increased globular/filamentous actin ratio, indicating actin depolymerization. Moreover, phosphoinositide-3-kinase subunit p85 phosphorylation, p21 protein-activated kinase (PAK1) phosphorylation, as well as vesicle-associated membrane protein 8 (VAMP8) expression were significantly reduced in platelets from patients with ChAc (by 17, 22, and 39%, respectively) and in megakaryocytic (MEG-01) cells following chorein silencing (by 16, 54, and 11%, respectively). Activation-induced platelet secretion from dense granules (ATP release) and α granules (P-selectin exposure) were significantly less (by 55% after stimulation with 1 µg/ml CRP and by 33% after stimulation with 5 µM TRAP, respectively) in ChAc platelets than in control platelets. Furthermore, platelet aggregation following stimulation with different platelet agonists was significantly impaired. These observations reveal a completely novel function of chorein, i.e., regulation of secretion and aggregation of blood platelets. [ABSTRACT FROM AUTHOR]

Aim Suicidal erythrocyte death or eryptosis is characterized by cell shrinkage and phosphatidylserine exposure at the cell surface. Eryptotic erythrocytes may adhere to the vascular wall by binding of phosphatidylserine to endothelial CXC chemokine ligand 16 ( CXCL16). Triggers of eryptosis include osmotic shock or energy depletion. Susceptibility to eryptosis is modified by Klotho, a protein with profound effect on ageing and lifespan. Klotho deficiency leads to accelerated ageing and early death. The percentage of eryptotic erythrocytes is significantly larger in klotho-deficient mice ( klotho −/−) than in their wild-type littermates ( klotho +/+). The present study explored whether the accelerated eryptosis of klotho-deficient mice is paralleled by enhanced adhesion. Methods Phosphatidylserine-exposing erythrocytes were identified by measurement of annexin V binding and adhesion to human umbilical vein endothelial cells ( HUVEC) from trapping of labelled erythrocytes in a flow chamber. Results Annexin V binding was higher in klotho −/− erythrocytes than in klotho +/+ erythrocytes. Osmotic shock for 1 h (addition of 550 m m sucrose) and energy depletion (12-h glucose depletion) increased annexin V binding to values again significantly larger in klotho −/− erythrocytes than in klotho +/+ erythrocytes. klotho −/− erythrocytes were particularly sensitive to osmotic shock. Both osmotic shock and energy depletion enhanced erythrocyte adhesion, an effect again more pronounced in klotho −/− erythrocytes than in klotho +/+ erythrocytes. The adhesion was significantly decreased by coating of phospatidylserine with annexin V (5 μL mL −1) or by coating of CXCL16 with neutralizing antibodies (4 μg mL −1). Conclusions klotho −/− erythrocytes are particularly sensitive to osmotic shock, and enhanced eryptosis of klotho −/− erythrocytes is paralleled by enhanced adhesion to endothelial CXCL16. [ABSTRACT FROM AUTHOR]

Background and purpose: Platelet stromal-cell-derived factor-1 (SDF-1) plays a pivotal role in angiogenesis and the regeneration of ischaemic tissue through the regulation of haematopoietic progenitor cells and is upregulated at the sites of vascular injury and platelet activation. Thus, SDF-1 has recently been discussed as a predictor in ischaemic diseases such as acute myocardial infarction. However, no clinical data pertinent to the investigation of the platelet SDF-1 expression in patients with stroke are available. Methods: We consecutively evaluated 196 patients who were admitted to the stroke unit with symptoms suspected for stroke. Surface expression of the platelet activation markers (P-selectin and GPIb) and the expression of platelet-bound SDF-1 were determined by two-colour whole blood flow cytometry. Results: Patients with transient ischaemic attack (TIA) as well as with ischaemic stroke showed similar levels of SDF-1 expression on hospital admission compared with patients with non-ischaemic (NI) events and with 30 healthy controls (TIA (mean fluorescence intensity ± SD): 31.5 ± 18.2 vs. NI: 26.4 ± 15.7; P = 0.361; stroke: 28.7 ± 19.8 vs. NI; P = 0.943; control: 26.1 ± 11.3; P > 0.05 compared with all). Platelet SDF-1 expression showed a trend with the severity of stroke according to National Institute of Health Stroke Scale score ( r = 0.125; P = 0.085), but significantly correlated with the peak levels of C-reactive protein ( r = 0.218; P = 0.002) and with the levels of platelet activation (P-selectin: r = 0.389; P = 0.001). Multifactorial analysis of covariance revealed a significant influence on platelet SDF-1 expression by smoking ( P = 0.019). Conclusions: Platelet SDF-1 surface expression did not show any significant difference in patients with TIA and ischaemic stroke compared with patients with NI events. Thus, single biomarker evaluation of platelet SDF-1 surface expression is not helpful to predict ischaemic stroke. [ABSTRACT FROM AUTHOR]

Background and purpose: Platelet collagen receptor glycoprotein VI (GPVI) contributes significantly to platelet adhesion and thrombus formation. We aimed to investigate GPVI in patients presenting with symptoms of acute cerebrovascular disease and to define GPVI as biomarker for acute stroke. Methods: We consecutively evaluated 205 patients, who admitted the stroke unit with symptoms for stroke. Surface expression of the platelet activation markers (GPVI, CD62P, GPIb) was determined by two-color whole blood flow cytometry. Results: Patients with transient ischemic attack (TIA) ( n = 18; 8.8%) as well as with stroke ( n = 133; 64.9%) showed a significantly enhanced GPVI expression (mean fluorescence intensity ± SD) on admission compared to patients with non-ischemic (NI) events ( n = 54; 26.3%) (TIA: 20.9 ± 7.1 vs. NI: 16.2 ± 3.9; P = 0.002; stroke: 20.4 ± 5.7 vs. NI; P = 0.002). Neither CD62P nor GPIb surface expression showed a significant difference. Logistic regression analysis revealed that on admission GPVI was associated with stroke independent of conventional laboratory markers such as C-reactive protein, blood glucose, and creatine kinase. Using a receiver operating characteristic curve on GPVI, we have determined the cut off value of 18.2 for stroke. Thus, patients with enhanced GPVI expression levels (≥18.2) had a 2.4-fold relative risk for stroke. Patients with elevated platelet GPVI expression level had a poorer clinical outcome in cumulative event-free survival for stroke, myocardial infarction, and cerebro-/cardiovascular death at 3-month follow-up (log rank; P = 0.045). Conclusions: These findings indicate that platelet GPVI surface expression is significantly enhanced in patients with TIA and stroke compared to patients with NI events. Determination of platelet-specific GPVI may be useful as an early biomarker for cerebral ischemia. [ABSTRACT FROM AUTHOR]

Purpose To evaluate acute changes in atrial and ventricular parameters by the use of cardiac magnetic resonance imaging (MRI) in patients with percutaneous transcatheter atrial septal defects (ASD) closure. Materials and Methods The study included 14 patients (six males and eight females, 45 ± 18 years) with congenital ASD. Cardiac MRI (1.5T Philips Intera CV) was performed before and within 24 hours after transcatheter ASD closure. Right atrial (RA) and left atrial (LA) dimensions, as well as right (RV) and left (LV) ventricular end-diastolic (ED) volumes were determined. Atrial size was assessed by planimetry of the maximum RA and LA areas in a standard four-chamber view, and ventricular volumes were calculated according to a modified Simpson's rule in short-axis views. Results The mean RA decreased significantly from 27.6 ± 6.4 cm2 before closure to 24.4 ± 5.6 cm2 after the procedure ( P = 0.0018), whereas the LA area did not change (24.1 ± 4.7 cm2 vs. 23.8 ± 5.2 cm2, P = 0.76). The RV volumes, volume index, and ejection fraction (EF) decreased significantly from 229 ± 64 mL to 181 ± 43 mL ( P < 0.001, average reduction = 19% ± 15%), from 126.0 ± 37.2 mL/m2 to 96.6 ± 28.6 mL/m2 ( P < 0.0001) and from 64 ± 5% to 58% ± 7% ( P = 0.01), respectively. The LV volumes and volume index remained unchanged (114 ± 25 mL vs. 118 ± 22 mL, P = 0.18, 63.5 ± 13.5 mL/m2 vs. 63.0 ± 17.4 mL/m2, P = 0.83). Left-right shunting decreased from 40% ± 15% to 9% ± 15% ( P < 0.001). Conclusion Cardiac MRI can reveal detailed information on acute changes in shunt fraction and ventricular dimensions after ASD closure. ASD closure by percutaneous transcatheter device implantation results within 24 hours in a significant reduction of shunt fraction, RA and RV sizes, and RV function, whereas LA and LV dimensions remain unchanged. J. Magn. Reson. Imaging 2007;25:1136-1140. © 2007 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

In vulnerable atherosclerotic plaques, intraplaque hemorrhages (IPH) result in hemolysis of red blood cells and release of hemoglobin and free hemin. Hemin activates platelets and leads to thrombosis. Agonism of the inhibitory platelet receptor ACKR3 inhibits hemin‐dependent platelet activation and thrombus formation. To characterize the effect of hemin and ACKR3 agonism on isolated human platelets, multi‐color flow cytometry and classical experimental setup such as light transmission aggregometry and a flow chamber assay were used. Hemin induces platelet aggregation and ex vivo platelet‐dependent thrombus formation on immobilized collagen under a low shear rate of 500 s−1, indicating that free hemin is a strong activator of platelet‐dependent thrombosis. Recently, we described that ACKR3 is a prominent inhibitory receptor of platelet activation. Specific ACKR3 agonists but not conventional antiplatelet compounds such as COX‐1 inhibitor (indometacin), ADP‐receptor blocker (cangrelor), or PAR1 inhibitor (ML161) inhibit both hemin‐dependent aggregation and thrombus formation. To further characterize the effect of hemin on platelet subpopulations, we established a multi‐color flow cytometry assay. We found that hemin induces procoagulant (CD42bpos/PAC‐1neg/AnnexinVpos), aggregatory (CD42bpos/PAC‐1pos/AnnexinVneg), and inflammatory (CD42bpos/CXCR4pos/ACKR3pos/AnnexinVpos) platelet subpopulations. Treatment with ACKR3 agonists significantly decreased the formation of procoagulant and ACKR3pos platelets in response to hemin. We conclude that hemin is a strong activator for the formation of procoagulant platelets and thrombus formation which is dependent on the function of ACKR3. Activation of ACKR3 using specific agonists may offer a therapeutic strategy to regulate the vulnerability of atherosclerotic plaques in areas of IPH. [ABSTRACT FROM AUTHOR]

Background Methods and Results Conclusion Platelet receptors ACKR3 and CXCR4 play a crucial role in a variety of cardiovascular diseases. Like most chemokine receptors, CXCR4 is a G protein coupled receptor that induces platelet activation. In contrast, the atypical chemokine receptor 3 (ACKR3) lacks the ability to activate heterotrimeric G proteins and its activation leads to platelet inhibition and attenuates thrombus formation. In nucleated cells, heterodimerization of ACKR3 with CXCR4 regulates CXCL12‐dependent signalling. The aim of our study was to investigate the formation of ACKR3/CXCR4 heterodimers in platelets and the subsequent consequences for platelet function.Using a proximity ligation assay (PLA, Duolink®) to screen for CXCR4/ACKR3 heterodimerization inducing compounds, we found that ACKR3 agonism but not conventional platelet agonists or endogen ligands lead to heterodimer formation. To further characterize the formation of ACKR3/CXCR4 heterodimers, we studied the CXCL12‐dependent platelet activation via CXCR4. Both, CXCL12‐dependent platelet aggregation and collagen‐dependent ex vivo thrombus formation were significantly downregulated by ACKR3 agonism. Moreover, platelet intracellular calcium and Akt signalling were increased by CXCL12 and again suppressed by ACKR3‐specific agonists. Previously, CXCL12 was shown to decrease platelet cAMP levels via CXCR4. Treatment with a specific ACKR3 agonist counteracted this CXCL12/CXCR4‐dependent cAMP decrease.Our results reveal that the formation of platelet ACKR3/CXCR4 heterodimers is dependent on ACKR3 rather than CXCR4. Furthermore, ACKR3 agonism induced heterodimerization is associated with mitigating CXCL12/CXCR4‐dependent platelet activation possibly by modulating CXCR4‐dependent G protein signalling. Our results indicate possible ACKR3 agonist functions and reinforce the potential therapeutic applications of ACKR3 agonists. [ABSTRACT FROM AUTHOR]

Hemodialysis is associated with the formation of platelet-leukocyte aggregates. Whether this phenomenon is hemodialysis (HD) membrane dependent is unclear. To evaluate this process, we examined respectively platelet activation (anti-CD41, anti-CD62, and antifibrinogen monoclonal antibodies [MoAb] binding), leukocyte activation (CD11b expression), and the appearance of platelet specific antigens on leukocytes as an index of platelet-leukocyte aggregation during HD using 3 different membrane materials, Cuprophan, Hemophan, and polysulfone. Flow cytometric techniques and specific MoAb were used. All parameters were assayed 5 min after initiation of HD to avoid the confounding variable of leukopenia and resultant cell subpopulation analysis. Platelet activation (anti-CD62 and antifibrinogen binding) occurred only with Cuprophan. All 3 membranes induced equivalent increases in CD11b expression on neutrophils and similarly increased the binding of anti-CD41 to neutrophils, reflecting an increment in the formation of platelet neutrophil aggregates. However, only Cuprophan induced an increase in anti-CD62 binding to neutrophils, suggesting that the aggregated platelets linked to neutrophils were activated. Increased anti-CD41 binding by monocytes was similarly observed with all 3 membranes. However, only polysulfone induced an increase in CD11b expression and fibrinogen binding to monocytes. We conclude that while the formation of platelet leukocyte aggregates appears to be a universal phenomenon in HD occurring with a variety of membrane types, subtypes of this phenomenon consisting of activated platelets and fibrinogen binding may be membrane dependent. This phenomenon may serve as a new biocompatibility parameter and may shed light on some of the biologic consequences of hemodialysis. [ABSTRACT FROM AUTHOR]

The article provides information on the results of a research on the differention of human CD34+ progenitor cells into foam cells and endothelial cells induced by platelets. It was found that modified low density lipoprotein is picked up by platelets and accumulated in organelles containing mepacrine. It says that platelets affixed with Dil-AcLDL are fastly internalized into foam cells as presented by electron and fluorescence microscopy.

Presents a study on the effects of soluble glycoprotein VI (GPVI) dimer on platelet adhesion and aggregation to the injured vessel wall in vivo. Cloning, viral expression and purification of soluble human and murine GPVI; Binding of soluble GPVI to immobilize collagen; Conclusions of the study.

The article presents clinical images of a 71-year-old man diagnosed with eosinophilic granulomatosis with polyangiitis (Churg-Strauss) (EGPA) with giant coronary aneurysms of the right and the left coronary arteries.