scholarly journals Genetic inhibition of PCSK9, atherogenic lipoprotein concentrations, and calcific aortic valve stenosis

2019 ◽  
Author(s):  
Nicolas Perrot ◽  
Donato Moschetta ◽  
S. Matthijs Boekholdt ◽  
Vincenza Valerio ◽  
Andreas Martinsson ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Aortic Valve ◽  
Aortic Valve Stenosis ◽  
Uk Biobank ◽  
Lipid Levels ◽  
Aortic Valves ◽  
Lipoprotein Lipid ◽  
Calcium Deposits ◽  
Pcsk9 Inhibition ◽  
The Uk

AbstractBackgroundProprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition reduces plasma concentrations of low-density lipoprotein cholesterol (LDL-C), apolipoprotein B (apoB) and lipoprotein(a) [Lp(a)]. Atherogenic lipoprotein levels have been linked with calcific aortic valve stenosis (CAVS). Our objectives were to determine the association between variants in PCSK9 and lipoprotein-lipid levels, coronary artery disease (CAD) and CAVS, and to evaluate if PCSK9 could be implicated in aortic valve interstitial cells (VICs) calcification.MethodsWe built a genetic risk score weight for LDL-C levels (wGRS) using 10 independent PCSK9 single nucleotide polymorphisms and determined its association with lipoprotein-lipid levels in 9692 participants of the EPIC-Norfolk study. We investigated the association between the wGRS and CAD and CAVS in the UK Biobank, as well as the association between the PCSK9 R46L variant and CAVS in a meta-analysis of published prospective, population-based studies (Copenhagen studies, 1463 cases/101,620 controls) and unpublished studies (UK Biobank, 1350 cases/349,043 controls, Malmö Diet and Cancer study, 682 cases/5963 controls and EPIC-Norfolk study, 508 cases/20,421 controls). We evaluated PCSK9 expression and localization in explanted aortic valves by capillary Western blot and immunohistochemistry in patients with and without CAVS. Von Kossa staining was used to visualize aortic leaflet calcium deposits. PCSK9 expression under oxidative stress conditions in VICs was assessed.ResultsThe wGRS was significantly associated with lower LDL-C and apoB (p<0.001), but not with Lp(a). In the UK Biobank, the association of PCSK9 variants with CAD were positively correlated with their effects on apoB levels. CAVS was less prevalent in carriers of the PCSK9 R46L variant [odds ratio=0.71 (95% confidence interval, 0.57-0.88), p<0.001]. PCSK9 expression was elevated in the aortic valves of patients with aortic sclerosis and CAVS compared to controls. In calcified leaflets, PCSK9 co-localized with calcium deposits. PCSK9 expression was induced by oxidative stress in VICs.ConclusionGenetic inhibition of PCSK9 is associated with lifelong reductions in the levels of non-Lp(a) apoB-containing lipoproteins as well as lower odds of CAD and CAVS. PCSK9 is abundant in fibrotic and calcified aortic leaflets. Oxidative stress increases PCSK9 expression in VICs. These results provide a rationale for performing randomized clinical trials of PCSK9 inhibition in CAVS.

P4667Loss of function in PCSK9, atherogenic lipoprotein concentrations, and calcific aortic valve stenosis

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
N Perrot ◽  
D Moschetta ◽  
S M Boekholdt ◽  
V Valerio ◽  
A Martinsson ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Aortic Valve ◽  
Aortic Valve Stenosis ◽  
Genetic Risk Score ◽  
Plasma Concentrations ◽  
Aortic Valves ◽  
Atherogenic Lipoprotein ◽  
Weighted Genetic Risk Score ◽  
Calcium Deposits ◽  
Pcsk9 Inhibition

Abstract Background Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition reduces plasma concentrations of most atherogenic lipoproteins such as low-density lipoprotein cholesterol (LDL-C), apolipoprotein B (apoB) and lipoprotein(a) [Lp(a)]. Atherogenic lipoprotein concentrations have also been linked with calcific aortic valve stenosis (CAVS). Purpose 1) To determine the association between genetic variants in PCSK9 and lipoprotein-lipid levels, 2) to determine whether loss of function (LOF) in PCSK9 is associated with CAVS and 3) to evaluate if PCSK9 could be implicated in aortic valve interstitial cells (VICs) calcification. Methods We built a weighted genetic risk score (wGRS) using 10 single nucleotide polymorphisms at the PCSK9 locus associated with LDL-C in the Global Lipids Genetics Consortium. We determined the association between the wGRS and LDL-C, apoB and Lp(a)] in 9692 participants of the EPIC-Norfolk study using linear regression. We investigated the association between the LOF PCSK9 R46L variant and CAVS risk in a meta-analysis of published (three Copenhagen studies, 1463 cases and 101,620 controls) and unpublished studies (UK Biobank, 1350 cases and 349,043 controls, Malmö Diet and Cancer study, 682 cases and 5963 controls and EPIC-Norfolk, 508 cases and 20,421 controls) prospective, population-based studies using logistic regression adjusted for age and sex. We evaluated PCSK9 expression and localization in explanted aortic valves by capillary Western blot and immunohistochemistry in patients with and without CAVS. Von Kossa staining was used to visualize aortic leaflet calcium deposits. We also assessed VICs calcification potential under oxidative stress condition. Results In EPIC-Norfolk, the wGRS was significantly associated with TC, LDL-C, and apoB (all p<0.0001), but not with VLDL-C, HDL-C, triglycerides apoA-I, or Lp(a). Carriers of the R46L variant were at lower CAVS risk (odds ratio=0.71 (95% CI, 0.57–0.88, p<0.001)). Aortic valves of patients with aortic sclerosis (n=12) and CAVS (n=8) presented elevated PCSK9 levels (log2 fold change [FC]=+28.6±5.1, p=0.008 and FC=+39.3±15.2, p=0.02, respectively) compared to controls (n=4).In calcified leaflets, PCSK9 expression co-localized with calcium deposits. PCSK9 expression in VICs was induced by oxidative stress (FC=+2.3±0.4, p=0.02), and subsequent increment in calcification potential was observed. Conclusion PCSK9LOF variants are associated with lifelong reductions in non-Lp(a) apoB-containing lipoprotein levels and a lower risk of coronary artery disease and CAVS. PCSK9 is abundant in fibrotic and calcified aortic leaflets. Oxidative stress increases PCSK9 expression in VICs. These results support randomized clinical trials of PCSK9 inhibition in the prevention of CAVS.

scholarly journals Semicarbazide-Sensitive Amine Oxidase Increases in Calcific Aortic Valve Stenosis and Contributes to Valvular Interstitial Cell Calcification

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Nathalie Mercier ◽  
Sven-Christian Pawelzik ◽  
John Pirault ◽  
Miguel Carracedo ◽  
Oscar Persson ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Aortic Valve ◽  
Aortic Valve Stenosis ◽  
Interstitial Cell ◽  
Amine Oxidase ◽  
Primary Amines ◽  
Common Disease ◽  
Mrna Levels ◽  
Aortic Valves ◽  
Valve Calcification

Introduction. Calcific aortic valve stenosis (CAVS) is a common disease associated with aging. Oxidative stress participates in the valve calcification process in CAVS. Semicarbazide-sensitive amine oxidase (SSAO), also referred to as vascular adhesion protein 1 (VAP-1), transforms primary amines into aldehydes, generating hydrogen peroxide and ammonia. SSAO is expressed in calcified aortic valves, but its role in valve calcification has remained largely unexplored. The aims of this study were to characterize the expression and the activity of SSAO during aortic valve calcification and to establish the effects of SSAO inhibition on human valvular interstitial cell (VIC) calcification. Methods. Human aortic valves from n=80 patients were used for mRNA extraction and expression analysis, Western blot, SSAO activity determination, immunohistochemistry, and the isolation of primary VIC cultures. Results. SSAO mRNA, protein, and activity were increased with increasing calcification within human aortic valves and localized in the vicinity of the calcified zones. The valvular SSAO upregulation was consistent after stratification of the subjects according to cardiovascular and CAVS risk factors associated with increased oxidative stress: body mass index, diabetes, and smoking. SSAO mRNA levels were significantly associated with poly(ADP-ribose) polymerase 1 (PARP1) in calcified tissue. Calcification of VIC was inhibited in the presence of the specific SSAO inhibitor LJP1586. Conclusion. The association of SSAO expression and activity with valvular calcification and oxidative stress as well as the decreased VIC calcification by SSAO inhibition points to SSAO as a possible marker and therapeutic target to be further explored in CAVS.

70 OXIDATIVE STRESS AND AORTIC VALVE STENOSIS

2008 ◽  
Vol 18 ◽  
pp. S51
Author(s):  
F. Minardi ◽  
V. Cavalca ◽  
L. Dainese ◽  
F. Veglia ◽  
A. Guarino ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Aortic Valve ◽  
Aortic Valve Stenosis

Abstract 17341: Novel Lipid Markers of Calcific Aortic Valve Stenosis

Circulation ◽  
2018 ◽  
Vol 138 (Suppl_1) ◽  
Author(s):  
Pascal E Bogaert ◽  
Andrea L Edel ◽  
Arun Surendran ◽  
Michael Raabe ◽  
Shubhkarman Sandhawalia ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Pressure Gradient ◽  
Aortic Valve Stenosis ◽  
Internal Standard ◽  
Aortic Valves ◽  
Genetic Studies ◽  
High Incidence ◽  
Oxidized Phosphatidylcholine ◽  
Human Aortic Valve ◽  
Severe Calcification

Introduction: Calcific aortic valve stenosis (CAVS) is the most prevalent cardiac valvular pathology, leading to a high incidence of morbidity and mortality if left untreated. The exact pathophysiology of CAVS is largely undefined. Genetic studies have shown a strong correlation of the Lp(a) gene to developing CAVS. Lp(a) is known to be the carrier of plasma Oxidized Phosphatidylcholine and results in Lysophosphatidic acid (LPA) accumulation. The focus of the present study was to determine if OxPC and LPA in calcific human aortic valves relate with echocardiographic markers of CAVS. Methods: Aortic valves (n=98) were obtained from patients undergoing AVR. OxPC and LPA were extracted from pulverized aortic valves and analyzed using a targeted mass spectrometry approach. Lipid values are represented relative to an internal standard and normalized by homogenate and leaflet weights. The severity of calcification and aortic stenosis were measured anatomically by Echocardiographic calcification (ECC) score and hemodynamically by mean AV pressure gradient. Results: One-palmitoyl-2-(9-oxo)-nonanoyl- sn- glycero-3-phosphocholine (PONPC) was the most abundant OxPC among 58 OxPC molecules detected (49.3±3.8ng), in AV tissue. When valves were graded by ECC score, scores of 1 (no calcification) had observably attenuated amounts of mean total OxPC’s (135.3±39.3ng) compared to those with a score of 4 (severe calcification) (310.1±34.8 ng). Total valvular OxPC increased linearly with increased ECC score. Total non-fragmented OxPC’s were also significantly lower in valves with ECC scores of 1 and 2 compared to a score of 4 ( P =0.03). Six LPA species were also identified with 16:0 and 18:1 being the most prevalent. Mean AV pressure gradient had a significant, positive correlation with Total LPA amounts (r 2 =0.580, p <0.001), suggesting that elevated LPA concentrations in CAVS tissue is associated with disease severity. Conclusions: Our study is the largest lipidomics study of human aortic valve tissue demonstrating that OxPC and LPA molecules play a significant role in the etiology of CAVS and provides a novel therapeutic target for mitigating disease progression.

scholarly journals Body mass index and body composition in relation to 14 cardiovascular conditions in UK Biobank: a Mendelian randomization study

2019 ◽  
Vol 41 (2) ◽  
pp. 221-226 ◽  
Author(s):  
Susanna C Larsson ◽  
Magnus Bäck ◽  
Jessica M B Rees ◽  
Amy M Mason ◽  
Stephen Burgess
Keyword(s):  
Atrial Fibrillation ◽  
Body Mass Index ◽  
Aortic Valve ◽  
Aortic Valve Stenosis ◽  
Fat Mass ◽  
Mendelian Randomization ◽  
Fat Free Mass ◽  
Uk Biobank ◽  
Fat Mass Index ◽  
Artery Disease

Abstract Aims The causal role of adiposity for several cardiovascular diseases (CVDs) is unclear. Our primary aim was to apply the Mendelian randomization design to investigate the associations of body mass index (BMI) with 13 CVDs and arterial hypertension. We also assessed the roles of fat mass and fat-free mass on the same outcomes. Methods and results Single-nucleotide polymorphisms associated with BMI and fat mass and fat-free mass indices were used as instrumental variables to estimate the associations with the cardiovascular conditions among 367 703 UK Biobank participants. After correcting for multiple testing, genetically predicted BMI was significantly positively associated with eight outcomes, including and with decreasing magnitude of association: aortic valve stenosis, heart failure, deep vein thrombosis, arterial hypertension, peripheral artery disease, coronary artery disease, atrial fibrillation, and pulmonary embolism. The odds ratio (OR) per 1 kg/m2 increase in BMI ranged from 1.06 [95% confidence interval (CI) 1.02–1.11; P = 2.6 × 10−3] for pulmonary embolism to 1.13 (95% CI 1.05–1.21; P = 1.2 × 10−3) for aortic valve stenosis. There was suggestive evidence of positive associations of genetically predicted fat mass index with nine outcomes (P &lt; 0.05). The strongest magnitude of association was with aortic valve stenosis (OR per 1 kg/m2 increase in fat mass index 1.46, 95% CI 1.13–1.88; P = 3.9 × 10−3). There was suggestive evidence of inverse associations of fat-free mass index with atrial fibrillation, ischaemic stroke, and abdominal aortic aneurysm. Conclusion This study provides evidence that higher BMI and particularly fat mass index are associated with increased risk of aortic valve stenosis and most other cardiovascular conditions.

scholarly journals HDL-C Role in Acquired Aortic Valve Stenosis Patients and Its Relationship with Oxidative Stress

Medicina ◽  
2019 ◽  
Vol 55 (8) ◽  
pp. 416
Author(s):  
Hofmanis ◽  
Hofmane ◽  
Svirskis ◽  
Mackevics ◽  
Tretjakovs ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Aortic Valve ◽  
Aortic Valve Stenosis ◽  
Density Lipoprotein ◽  
Thioredoxin Reductase ◽  
Endothelial Damage ◽  
Control Group ◽  
Clear Correlation ◽  
Stenosis Severity ◽  
Stress Oxidative

Background and objectives: Mechanical stress is currently considered as the main factor promoting calcific aortic valve stenosis (AS) onset. It causes endothelial damage and dysfunction. The chronic inflammatory process causes oxidative stress. Oxidative stress-induced high-density lipoprotein cholesterol (HDL-C) dysfunction is an important component of the development of AS. The aim of the study was to evaluate the role of HDL-C in AS patients in three severity grades and in relation to the biomarkers of oxidative stress, thioredoxin reductase 1 (TrxR1) and myeloperoxidase (MPO). Materials and Methods: 18 patients with mild, 19 with moderate. and 15 with severe AS were included in the study, and 50 individuals were enrolled in the control group. Stenosis severity was determined by echocardiography. The TrxR1 and MPO were analyzed by ELISA, and HDL-C by commercially available tests. Data were analyzed using GraphPad Prism 8. Results: HDL-C in AS patients vs. control substantially decreases and this decline was observed in all three AS severity groups: mild (p = 0.018), moderate (p = 0.0002), and severe (p = 0.004). In both the control and the stenosis group, the HDL-C was higher in women than in men. In comparison to control, the HDL-C level was lower in the AS group, and more pronounced in women (p = 0.0001) than in men (p = 0.049). A higher TrxR1 level was observed in patients with mild (p = 0.0001) and severe AS (p = 0.047). However, a clear correlation between TrxR1 and HDL-C was not obtained. Analysis of MPO showed differences in all severity grades vs. control (p = 0.024 mild stenosis; p = 0.002 moderate stenosis; p = 0.0015 severe stenosis). A negative correlation (p = 0.047; rp = −0.28) was found between MPO and HDL-C, which confirms the adverse effects of MPO resulting in HDL-C dysfunction. Conclusions: In this study, we justified HDL-C level association with AS development process. The results unequivocally substantiated the association between HDL-C and AS in all severity grades in women, but only in moderate AS for men, which we explained by the small number of men in the groups. The obtained correlation between the HDL-C and MPO levels, as well as the concurrent decrease in the HDL-C level and increase in the TrxR1 level, indicate in general an HDL-C association with oxidative stress in AS patients.

Abstract 348: Effects of Normalizing Hyperlipidemia on Oxidative Stress and Disease Progression in a Mouse Model of Aortic Valve Stenosis

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Jordan D Miller ◽  
Christopher J Berry ◽  
Kristine M Serrano ◽  
Robert M Weiss ◽  
Nikhil K Iyengar ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Aortic Valve ◽  
Total Cholesterol ◽  
Aortic Valve Stenosis ◽  
Aortic Valve Disease ◽  
Separation Distance ◽  
Valve Disease ◽  
Genetic Switch ◽  
Cholesterol Levels ◽  
Valve Area

Treatment of hyperlipidemia produces functional and structural improvement in atherosclerotic vessels. Effects of treatment of hyperlipidemia on structure and function of the aortic valve, however, are controversial, and may be confounded by pleiotropic effects of drugs. We hypothesized treatment of hyperlipidemia using a “genetic switch” in Reversa mice ( Ldlr −/ − / Apob 100/100 / Mttp fl/fl /Mx1 Cre + / + ) would reduce oxidative stress and slow the progression of aortic valve disease. Following 6 months of hyperlipidemia (cholate-free Western diet = WD = 0.25% chol., 21% fat; total cholesterol levels >700 mg/dl), superoxide levels were significantly elevated in the aortic valve (dihydroethidium fluorescence: control = 5 ± 2 U/pixel, WD = 13 ± 3 U/pixel; p < 0.05) with very small reductions in maximum leaflet separation distance obtained from echocardiograms (control = 0.94 ± 0.07 mm, WD =0.89 ± 0.02 mm; p<0.05). In mice maintained on WD for an additional 6 months, leaflet separation decreased to 0.66 ± 0.06 mm (p < 0.05). Rapid normalization of cholesterol levels at 6 months (NC; total cholesterol <200 mg/dl) using a “genetic switch” normalized superoxide levels in the valve (NC = 4 ± 2 U/pixel, p = n.s. versus control animals) and prevented further reductions in leaflet separation distance (NC = 0.89 ± 0.05 mm; p = n.s.). Computerized planimetry of aortic valve area from high resolution cross-sectional magnetic resonance images through the aortic root (4.7 Tesla magnet, 0.04 mm 2 in-plane pixel resolution) confirmed that normalization of cholesterol levels significantly slowed the rate of progression of valve stenosis (Δ valve area from 6–12 months: HC=−6.4 ± 4 %/month, NC = 0.6 ± 4%/month, p<0.05). Collectively, these data suggest that normalization of lipid levels in hypercholesterolemic mice with mild aortic valve disease normalizes oxidative stress and slows the progression of aortic valve stenosis.

Abstract 288: Mice With Disruptive Egfr Signaling In The Aortic Valves Develop Calcific Aortic Valve Stenosis

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Bin Zhou ◽  
Bingruo Wu
Keyword(s):  
Aortic Valve ◽  
Aortic Valve Stenosis ◽  
Clinical Importance ◽  
Interstitial Cells ◽  
Left Ventricular ◽  
Specific Gene ◽  
Egfr Signaling ◽  
Aortic Valves ◽  
Major Health Problem ◽  
Mesenchymal Transition

Calcific aortic valve stenosis is a major health problem. Despite its clinical importance, the pathogenesis of this condition remains illusive. Aortic valves are made of endothelial cells and interstitial cells, both are derived from the endocardial cells of the heart during development. We have developed a new mouse model, Nfatc1-Cre, to specifically study the biology of the valve cells during valve development. In this study, we deleted epidermal growth factor receptor (Egfr) in the aortic valves using the Nfatc1-Cre and showed by histological and biochemical analyses that this deletion caused a spectrum of pathological characteristics of human calcific aortic valve stenosis. They include increased proliferation and dedifferentiation of the valve interstitial cells, abnormal deposition of extracellular matrix, bone-like formation and calcification. The null mice eventually developed the left ventricular dysfunction, presumably secondary to the stenotic aortic valves. We also revealed by immunohistochemistry and quantitative RT-PCR the changes in gene expression involved in the epithelial-to-mesenchymal transition or osteogenic activities. Altogether, these results demonstrate that Egfr signaling in the valve endothelial and interstitial cells regulates the homeostasis of the aortic valves and suggest that patients with mutations or medications affecting the Egfr signaling may be at the risk to develop calcific aortic valve stenosis. Our study also provides the proof-of-principle data showing that the Nfatc1-Cre is a useful genetic tool to elucidate the valve-specific gene function involved in the valve homeostasis and disease.

P5988Non-classical Ly6C-low monocytes contribute to aortic valve stenosis development in mice

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
S T Niepmann ◽  
C Weissheit ◽  
J Kleiner ◽  
C Kurts ◽  
G Nickenig ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Aortic Valve ◽  
Aortic Valve Stenosis ◽  
Immune Cells ◽  
Peak Velocity ◽  
Western World ◽  
Monocyte Count ◽  
Aortic Valves ◽  
Exact Function ◽  
Deficient Mice

Abstract Introduction Aortic valve stenosis (AS) is one of the most common valvular diseases in the western world. Once patients with AS develop symptoms mortality increases up to 50% over two years. For many years AS was believed to be a passive degenerative process. Recent findings suggest a more complex pathomechanism with a strict molecular and cellular regulation involving local inflammation and invasion of immune cells. Specifically, pro-inflammatory macrophages have been shown to play an important role in disease progression. On the other hand, monocyte counts in the peripheral blood of patients with severe AS are significantly decreased and there is an inverse correlation between valve orifice area and circulating monocyte count. In order to elucidate the exact function of pro-inflammatory classical (Ly6C-high) and non-classical (Ly6C-low) monocytes in disease initiation processes, we conducted a series of experiments in a model of murine AS. Methods In this study 10–12 weeks old male C57BL6/J or CX3CR1-deficient mice were investigated. For AS induction, a coronary springwire was introduced into the left ventricle, pushed and rotated over the aortic valve under echocardiographic guidance. In sham operated mice the wire was only inserted into the left carotid artery without manipulation of the aortic valve. Development of AS was confirmed via weekly ultrasound examinations. Immune cells in the aortic valve were quantified using flow cytometry and immunofluorescence microscopy. Results Ultrasound analysis after two weeks confirmed the development of AS in the injured wildtype mice. Transaortic peak velocity levels were significantly increased compared to sham operated mice. Flow cytometry of explanted aortic valves showed a strong cellular immunoreaction in the stenotic valves. The amount of anti-inflammatory Ly6C-low monocytes was significantly increased compared to sham-mice, whereas the number of pro-inflammatory Ly6C-high monocytes remained stable. Interestingly CD-4 positive T-cells were augmented in stenotic aortic valves. Immunofluorescence confirmed Ly6C-low monocytes infiltration in the valve, in close proximity to the endothelial cells on the ventricular and the aortic side. The expression of recruitment and adhesion markers CD11b and CX3CR1 were significantly increased on the surface of the Ly6C-low monocytes of AS mice. To investigate the role of Ly6C-low monocytes in AS development, CX3CR1 deficient mice, which are not able to recruit non-classical monocytes via CX3CR1, were subjected to aortic valve wire injury. After two weeks, peak velocity levels in CX3CR1−/− mice remained nearly unchanged and were significantly decreased compared to wildtype mice. Conclusion Our data suggest that non-classical Ly6Clow monocytes play a crucial role in AS development in mice. Therefore, they may be targets for future therapeutic interventions. Acknowledgement/Funding S.T.N. was funded by Else-Kröner-Fresenius-Foundation of the Medical Faculty of the University of Bonn

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