Matthias Stuber

Publications (225) View all

• Article: Effect of dark chocolate on renal tissue oxygenation as measured by BOLD-MRI in healthy volunteers.

  Menno Pruijm, Lucie Hofmann, Julie Charollais-Thoenig, Valentina Forni, Marc Maillard, Andrew Coristine, Matthias Stuber, Michel Burnier, Bruno Vogt
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  ABSTRACT: Background: Cocoa is rich in flavonoids, has anti-oxidative properties and increases the bioavailability of nitric oxide (NO). Adequate renal tissue oxygenation is crucial for the maintenance of renal function. The goal of this study was to investigate the effect of cocoa-rich dark chocolate (DC) on renal tissue oxygenation in humans, as compared to flavonoid-poor white chocolate (WC). Methods: Ten healthy volunteers with preserved kidney function (mean age ± SD 35 ± 12 years, 70% women, BMI 21 ± 3 kg/m2) underwent blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) before and 2 hours after the ingestion of 1 g/kg of DC (70% cocoa). Renal tissue oxygenation was determined by the measurement of R2* maps on 4 coronal slices covering both kidneys. The mean R2* (= 1/T2*) values in the medulla and cortex were calculated, a low R2* indicating high tissue oxygenation. Eight participants also underwent BOLD-MRI at least 1 week later, before and 2 hours after the intake of 1 g/kg WC. Results: The mean medullary R2* was lower after DC intake compared to baseline (28.2 ± 1.3 s-1 vs. 29.6 ± 1.3 s-1, p = 0.04), whereas cortical and medullary R2* values did not change after WC intake. The change in medullary R2* correlated with the level of circulating (epi)catechines, metabolites of flavonoids (r = 0.74, p = 0.037), and was independent of plasma renin activity. Conclusion: This study suggests for the first time an increase of renal medullary oxygenation after intake of dark chocolate. Whether this is linked to flavonoid-induced changes in renal perfusion or oxygen consumption, and whether cocoa has potentially renoprotective properties, merits further study.
  Clinical nephrology 04/2013; · 1.17 Impact Factor
• Article: Steady-state equilibrium phase inversion recovery ON-resonant water suppression (IRON) MR angiography in conjunction with superparamagnetic nanoparticles. A robust technique for imaging within a wide range of contrast agent dosages.

  Gitsios Gitsioudis, Matthias Stuber, Ingolf Arend, Moritz Thomas, Jing Yu, Thomas Hilbel, Evangelos Giannitsis, Hugo A Katus, Grigorios Korosoglou
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  ABSTRACT: PURPOSE: To investigate the ability of inversion recovery ON-resonant water suppression (IRON) in conjunction with P904 (superparamagnetic nanoparticles which consisting of a maghemite core coated with a low-molecular-weight amino-alcohol derivative of glucose) to perform steady-state equilibrium phase MR angiography (MRA) over a wide dose range. MATERIALS AND METHODS: Experiments were approved by the institutional animal care committee. Rabbits (n = 12) were imaged at baseline and serially after the administration of 10 incremental dosages of 0.57-5.7 mgFe/Kg P904. Conventional T(1) -weighted and IRON MRA were obtained on a clinical 1.5 Tesla (T) scanner to image the thoracic and abdominal aorta, and peripheral vessels. Contrast-to-noise ratios (CNR) and vessel sharpness were quantified. RESULTS: Using IRON MRA, CNR and vessel sharpness progressively increased with incremental dosages of the contrast agent P904, exhibiting constantly higher contrast values than T(1) -weighted MRA over a very wide range of contrast agent doses (CNR of 18.8 ± 5.6 for IRON versus 11.1 ± 2.8 for T(1) -weighted MRA at 1.71 mgFe/kg, P = 0.02 and 19.8 ± 5.9 for IRON versus -0.8 ± 1.4 for T(1) -weighted MRA at 3.99 mgFe/kg, P = 0.0002). Similar results were obtained for vessel sharpness in peripheral vessels, (Vessel sharpness of 46.76 ± 6.48% for IRON versus 33.20 ± 3.53% for T(1) -weighted MRA at 1.71 mgFe/Kg, P = 0.002, and of 48.66 ± 5.50% for IRON versus 19.00 ± 7.41% for T(1) -weighted MRA at 3.99 mgFe/Kg, P = 0.003). CONCLUSION: Our study suggests that quantitative CNR and vessel sharpness after the injection of P904 are consistently higher for IRON MRA when compared with conventional T(1) -weighted MRA. These findings apply for a wide range of contrast agent dosages. J. Magn. Reson. Imaging 2013;. © 2013 Wiley Periodicals, Inc.
  Journal of Magnetic Resonance Imaging 02/2013; · 2.70 Impact Factor
• Article: Selective In-Vivo Visualization of Immune-cell Infiltration in a Mouse Model of Autoimmune Myocarditis by Fluorine-19 Cardiac Magnetic Resonance.

  Ruud B van Heeswijk, Jonathan De Blois, Gabriela Kania, Christine Gonzales, Przemyslaw Blyszczuk, Matthias Stuber, Urs Eriksson, Juerg Schwitter
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  ABSTRACT: BACKGROUND: -The goal of this study was to characterize the performance of (19)F cardiac magnetic resonance (CMR) for the specific detection of inflammatory cells in a mouse model of myocarditis. Intravenously administered perfluorocarbons (PFC) are taken up by infiltrating inflammatory cells and can be detected by fluorine-19 ((19)F) CMR. (19)F-labeled cells should therefore generate an exclusive signal at the inflamed regions within the myocardium. METHODS AND RESULTS: -Experimental autoimmune myocarditis (EAM) was induced in BALB/c mice. Following intravenous injection of 2x200μl of a PFC on day 19 and 20 (n=9) after immunization, in vivo (19)F-CMR was performed at the peak of myocardial inflammation (day 21). In 5 additional animals, PFC combined with fluorescein isothiocyanate (FITC) was administered for post-mortem immunofluorescence and flow cytometry analyses. Control experiments were performed in 9 animals. In vivo (19)F-CMR detected myocardial inflammation in all EAM-positive animals. Its resolution was sufficient to identify even small inflammatory foci e.g. at the surface of the right ventricle. Post-mortem immunohistochemistry and flow cytometry confirmed the presence of PFC in macrophages, dendritic cells and granulocytes, but not in lymphocytes. The myocardial volume of elevated (19)F signal (r(s)=0.96, p<0.001), the (19)F SNR (r(s)=0.92, p<0.001) and the (19)F signal integral (r(s)=0.96, p<0.001) at day 21 correlated with the histological myocarditis severity score. CONCLUSIONS: -In-vivo (19)F-CMR was successfully used to specifically and robustly visualize the inflammation in EAM, and thus allowed for an unprecedented insight into the involvement of inflammatory cells in the disease process.
  Circulation Cardiovascular Imaging 01/2013; · 5.94 Impact Factor
• Article: Renal Tissue Oxygenation in Essential Hypertension and Chronic Kidney Disease.

  Menno Pruijm, Lucie Hofmann, Bruno Vogt, Marie-Eve Muller, Maciej Piskunowicz, Matthias Stuber, Michel Burnier
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  ABSTRACT: Animal studies suggest that renal tissue hypoxia plays an important role in the development of renal damage in hypertension and renal diseases, yet human data were scarce due to the lack of noninvasive methods. Over the last decade, blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI), detecting deoxyhemoglobin in hypoxic renal tissue, has become a powerful tool to assess kidney oxygenation noninvasively in humans. This paper provides an overview of BOLD-MRI studies performed in patients suffering from essential hypertension or chronic kidney disease (CKD). In line with animal studies, acute changes in cortical and medullary oxygenation have been observed after the administration of medication (furosemide, blockers of the renin-angiotensin system) or alterations in sodium intake in these patient groups, underlining the important role of renal sodium handling in kidney oxygenation. In contrast, no BOLD-MRI studies have convincingly demonstrated that renal oxygenation is chronically reduced in essential hypertension or in CKD or chronically altered after long-term medication intake. More studies are required to clarify this discrepancy and to further unravel the role of renal oxygenation in the development and progression of essential hypertension and CKD in humans.
  International journal of hypertension. 01/2013; 2013:696598.
• Article: Non-Invasive Detection of Coronary Endothelial Response to Sequential Handgrip Exercise in Coronary Artery Disease Patients and Healthy Adults.

  Allison G Hays, Matthias Stuber, Glenn A Hirsch, Jing Yu, Michael Schär, Robert G Weiss, Gary Gerstenblith, Sebastian Kelle
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  ABSTRACT: Our objective is to test the hypothesis that coronary endothelial function (CorEndoFx) does not change with repeated isometric handgrip (IHG) stress in CAD patients or healthy subjects. Coronary responses to endothelial-dependent stressors are important measures of vascular risk that can change in response to environmental stimuli or pharmacologic interventions. The evaluation of the effect of an acute intervention on endothelial response is only valid if the measurement does not change significantly in the short term under normal conditions. Using 3.0 Tesla (T) MRI, we non-invasively compared two coronary artery endothelial function measurements separated by a ten minute interval in healthy subjects and patients with coronary artery disease (CAD). Twenty healthy adult subjects and 12 CAD patients were studied on a commercial 3.0 T whole-body MR imaging system. Coronary cross-sectional area (CSA), peak diastolic coronary flow velocity (PDFV) and blood-flow were quantified before and during continuous IHG stress, an endothelial-dependent stressor. The IHG exercise with imaging was repeated after a 10 minute recovery period. In healthy adults, coronary artery CSA changes and blood-flow increases did not differ between the first and second stresses (mean % change ±SEM, first vs. second stress CSA: 14.8%±3.3% vs. 17.8%±3.6%, p = 0.24; PDFV: 27.5%±4.9% vs. 24.2%±4.5%, p = 0.54; blood-flow: 44.3%±8.3 vs. 44.8%±8.1, p = 0.84). The coronary vasoreactive responses in the CAD patients also did not differ between the first and second stresses (mean % change ±SEM, first stress vs. second stress: CSA: -6.4%±2.0% vs. -5.0%±2.4%, p = 0.22; PDFV: -4.0%±4.6% vs. -4.2%±5.3%, p = 0.83; blood-flow: -9.7%±5.1% vs. -8.7%±6.3%, p = 0.38). MRI measures of CorEndoFx are unchanged during repeated isometric handgrip exercise tests in CAD patients and healthy adults. These findings demonstrate the repeatability of noninvasive 3T MRI assessment of CorEndoFx and support its use in future studies designed to determine the effects of acute interventions on coronary vasoreactivity.
  PLoS ONE 01/2013; 8(3):e58047. · 4.09 Impact Factor