Gerhard Cvirn

Prof. Dr. Gerhard Cvirn

orcid

Research Focus & Metrics

Academic Career Length

19Years (2008-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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11 August 2017 in PLOS ONE
Verified
Journal Article
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MPMargret Paar
Margret Paar
CRChristine Rossmann
Christine Rossmann
CNChristoph Nusshold
Christoph Nusshold
TWThomas Wagner
Thomas Wagner
ASAxel Schlagenhauf
Axel Schlagenhauf
SHSeth Hallström
Seth Hallström
Albumin is the most abundant plasma protein. Critical illness is often associated with altered, predominately decreased, serum albumin levels. This hypoalbuminaemia is usually corrected by administration of exogenous albumin. This study aimed to track the concentration-dependent influence of albumin on blood coagulation in vitro. Whole blood (WB) samples from 25 volunteers were prepared to contain low (19.3 ± 7.7 g/L), physiological (45.2 ± 7.8 g/L), and high (67.5 ± 18.1 g/L) levels of albumin. Haemostatic profiling was performed using a platelet function analyzer (PFA) 200, impedance aggregometry, a Cone and Platelet analyzer (CPA), calibrated automated thrombogram, and thrombelastometry (TEM). Platelet aggregation-associated ATP release was assessed via HPLC analysis. In the low albumin group, when compared to the physiological albumin group, we found: i) shortened PFA 200-derived closure times indicating increased primary haemostasis; ii) increased impedance aggregometry-derived amplitudes, slopes, ATP release, as well as CPA-derived average size indicating improved platelet aggregation; iii) increased TEM-derived maximum clot firmness and alpha angles indicating enhanced clot formation. TEM measurements indicated impaired clot formation in the high albumin group compared with the physiological albumin group. Thus, albumin exerted significant anticoagulant action. Therefore, low albumin levels, often present in cancer or critically ill patients, might contribute to the frequently occurring venous thromboembolism.

25 May 2023 in Heliyon
Verified
Journal Article
Open access
CTChiara Turrina
Chiara Turrina
AKAnna Klassen
Anna Klassen
DMDavide Milani
Davide Milani
DRDiana M. Rojas-González
Diana M. Rojas-González
GLGerhard Ledinski
Gerhard Ledinski
Sebastian SchwamingerSebastian Schwaminger
Sebastian Schwaminger
Iron oxide nanoparticles (IONs) are of great interest in nanomedicine for imaging, drug delivery, or for hyperthermia treatment. Although many research groups have focused on the synthesis and application of IONs in nanomedicine, little is known about the influence of the surface properties on the particles' behavior in the human body. This study analyzes the impact of surface coatings (dextran, polyvinyl alcohol, polylactide-co-glycolide) on the nanoparticles’ cytocompatibility, agglomeration, degradation, and the resulting oxidative stress induced by the particle degradation. All particles, including bare IONs (BIONs), are highly cytocompatible (>70%) and show no significant toxicity towards smooth muscle cells. Small-angle X-ray scattering profiles visualize the aggregation behavior of nanoparticles and yield primary particle sizes of around 20 nm for the investigated nanoparticles. A combined experimental setup of dynamic light scattering and phenanthroline assay was used to analyze the long-term agglomeration and degradation profile of IONs in simulated body fluids, allowing fast screening of multiple candidates. All particles degraded in simulated endosomal and lysosomal fluid, confirming the pH-dependent dissolution. The degradation rate decreased with the shrinking size of particles leading to a plateau. The fastest Fe2+ release could be measured for the polyvinyl-coated IONs. The analytical setup is ideal for a quick preclinical study of IONs, giving often neglected yet crucial information about the behavior and toxicity of nanoparticles in the human body. Moreover, this study allows for the development and evaluation of novel ferroptosis-inducing agents.

23 March 2014 in European Heart Journal - Cardiovascular Imaging
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Journal Article
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MKMartin Koestenberger
Martin Koestenberger
WRWilliam Ravekes
William Ravekes
BNBert Nagel
Bert Nagel
AAAlexander Avian
Alexander Avian
BHBernd Heinzl
Bernd Heinzl
AGAndreas Gamillscheg
Andreas Gamillscheg
Quantitative determination of right ventricular (RV) function has gained more interest over the last years. The RV outflow tract systolic excursion (RVOT SE) has been recently proposed as an echocardiographic tool to assess RV systolic function in adults. We aimed to determine growth-related changes of RVOT SE in children and to establish references values. A prospective study was conducted in a group of 711 healthy paediatric patients (age: 1 day to 18 years). We determined the effects of age and body surface area (BSA) on RVOT SE values. RVOT SE values were further correlated with the established RV systolic function parameters tricuspid annular plane systolic excursion (TAPSE) and tricuspid annular peak systolic velocity (S'). The RVOT SE ranged from a mean of 3.4 mm in neonates to 9.5 mm in 18-year-old adolescents. The RVOT SE values showed a positive correlation with age (r = 0.90, P < 0.001) and BSA (r = 0.91, P < 0.001). A significant positive correlation was seen between RVOT SE and TAPSE (r = 0.93, P < 0.001) and also between RVOT SE and S' (r = 0.86, P < 0.001) in our patients. RVOT SE provides a simple measure and, in combination with long-axis excursion parameters TAPSE and S', a comprehensive assessment of RV systolic function. Z-scores of RVOT SE values were calculated, and percentile charts were established to serve as reference data.

24 June 2023 in Colloids and Surfaces B: Biointerfaces
Verified
Journal Article
Open access
CTChiara Turrina
Chiara Turrina
MSMax Schoenen
Max Schoenen
DMDavide Milani
Davide Milani
AKAnna Klassen
Anna Klassen
DGDiana M. Rojas Gonzaléz
Diana M. Rojas Gonzaléz
Sebastian SchwamingerSebastian Schwaminger
Sebastian Schwaminger
Coated iron oxide nanoparticles (IONs) are promising candidates for various applications in nanomedicine, including imaging, magnetic hyperthermia, and drug delivery. The application of IONs in nanomedicine is influenced by factors such as biocompatibility, surface properties, agglomeration, degradation behavior, and thrombogenicity. Therefore, it is essential to investigate the effects of coating material and thickness on the behavior and performance of IONs in the human body. In this study, IONs with a carboxymethyl dextran (CMD) coating and two thicknesses of silica coating (TEOS0.98, and TEOS3.91) were screened and compared to bare iron oxide nanoparticles (BIONs). All three coated particles showed good cytocompatibility (>70%) when tested with smooth muscle cells over three days. To investigate their potential long term behavior inside the human body, the Fe2+ release and hydrodynamic diameters of silica-coated and CMD (carboxymethyl dextrane)-coated IONs were analyzed in simulated body fluids for 72 h at 37 °C. The ION@CMD showed moderate agglomeration of around 100 nm in all four simulated fluids and dissolved faster than the silica-coated particles in artificial exosomal fluid and artificial lysosomal fluid. The particles with silica coating agglomerated in all tested simulated media above 1000 nm. Increased thickness of the silica coating led to decreased degradation of particles. Additionally, CMD coating resulted in nanoparticles with the least prothrombotic activity, and the thick silica coating apparently decreased the prothrombotic properties of nanoparticles compared to BIONs and ION@TEOS0.98. For magnetic resonance applications, ION@CMD and ION@TEOS3.91 showed comparatively high relaxation rates R2 values. In magnetic particle imaging experiments ION@TEOS3.91 yielded the highest normalized signal to noise ratio values and in magnetic hyperthermia studies, ION@CMD and ION@TEOS0.98 showed similar specific loss power. These findings demonstrate the potential of coated IONs in nanomedicine and emphasize the importance of understanding the effect of coating material and thickness on their behavior and performance in the human body.

13 May 2019 in Experimental Biology and Medicine
Verified
Journal Article
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ETErwin Tafeit
Erwin Tafeit
GCGerhard Cvirn
Gerhard Cvirn
MLManfred Lamprecht
Manfred Lamprecht
MHMarkus Hohensinn
Markus Hohensinn
RMReinhard Moeller
Reinhard Moeller
RHRenate Horejsi
Renate Horejsi
Body mass index is a common and well-known measure in daily life. A body mass index higher than 25 is assumed to be an indicator for overweight and obesity and a high amount of total body fat. But body mass index overestimates body fat in subjects with high muscle mass and underestimates it in persons with a low lean body mass, especially in elderly and diseased persons. In the present study, we investigate the performance of the body mass index as a measure of body fatness and its ability to distinguish between well-trained and untrained subjects. Twenty-one well-trained male members of a police task force named “Cobra” and 38 non-active controls, matched by age, weight and height were participants of the study. The age range of these subjects was between 30 and 45 years. Subcutaneous adipose tissue thicknesses and body fat distributions were measured non-invasively by an optical device named the “Lipometer.” Statistics were performed with SPSS. We found that the body mass index did not show a difference between the two groups, whereas all Lipometer results were able to discriminate significantly between the trained and untrained subjects. Furthermore, the receiver operating characteristic curve analysis was calculated and all Lipometer measurements provided significant results up to a correct classification of all subjects of 86.4%, which was for the lateral thigh body site. In conclusion, the body mass index was not able to recognize the difference between trained and untrained participants, while body fat distribution measured with the Lipometer was able to distinguish more clearly the large body fat differences between these two groups. Impact statement: Body mass index (BMI) is a common measure of body fatness but overestimates body fat in subjects with high muscle mass. We have developed previously a device named “Lipometer,” an alternative way to measure body fatness. We show herein that the Lipometer is able to distinguish more clearly (than the BMI) the large body fat differences between well-trained and untrained subjects. Thus, the Lipometer is superior to BMI with respect to body fat measurements.

17 November 2017 in Seminars in Thrombosis and Hemostasis
Verified
Journal Article
Closed access
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RRReinhard Bernd Raggam
Reinhard Bernd Raggam
FHFranz Hafner
Franz Hafner
AAAlexander Avian
Alexander Avian
GHGerald Hackl
Gerald Hackl
GCGerhard Cvirn
Gerhard Cvirn
PRPeter Rief
Peter Rief
The aim of this study was prospective evaluation of the performance of the HAS-BLED score in predicting major bleeding complications in a real-world outpatient cohort, during long-term anticoagulation for venous thromboembolism (VTE), treated with a broad spectrum of anticoagulants. We analyzed 111 outpatients objectively diagnosed with VTE and treated long-term with various anticoagulants. Patients were grouped in three cohorts based on the anticoagulant regimen. Calculation of the HAS-BLED score and documentation of bleeding events were performed every 6 months for 1 year. Patients with a HAS-BLED score ≥ 3 had an increased risk for major bleeding events (odds ratio [OR]: 13.05, 95% confidence interval [CI]: 0.96–692.58, p = 0.028) and a trend to higher risk for minor bleeding events as well (OR: 2.25, 95% CI: 0.87–5.85, p = 0.091) when compared with patients with a HAS-BLED score < 3.This indicates that a HAS-BLED score ≥ 3 allows for identification of patients with VTE on long-term anticoagulation at an increased risk for major bleeding events, irrespective of the anticoagulant agent used.