Angiotensin production by the heart: a quantitative study in pigs with the use of radiolabeled angiotensin infusions

BACKGROUND: Beneficial effects of ACE inhibitors on the heart may be mediated by decreased cardiac angiotensin II (Ang II) production. METHODS AND RESULTS: To determine whether cardiac Ang I and Ang II are produced in situ or derived from the circulation, we infused 125I-labeled Ang I or II into pigs (25 to 30 kg) and measured 125I-Ang I and II as well

Equivariant vector bundles on quantum homogeneous spaces

The notion of quantum group equivariant homogeneous vector bundles on quantum homogeneous spaces is introduced. The category of such quantum vector bundles is shown to be exact, and its Grothendieck group is determined. It is also shown that the algebras of functions on quantum homogeneous spaces are noetherian

Angiotensin-converting enzyme inhibition and angiotensin II type 1 receptor blockade prevent cardiac remodeling in pigs after myocardial infarction: role of tissue angiotensin II

BACKGROUND: The mechanisms behind the beneficial effects of renin-angiotensin system blockade after myocardial infarction (MI) are not fully elucidated but may include interference with tissue angiotensin II (Ang II). METHODS AND RESULTS: Forty-nine pigs underwent coronary artery ligation or sham operation and were studied up to 6 weeks. To determine coronary angiotensin I (Ang I) to Ang II conversion and to distinguish plasma-derived Ang II from locally synthesized Ang II, (125)I-labeled and endogenous Ang I and II were measured in plasma and in infarcted and noninfarcted left ventricle (LV) during (125)I-Ang I infusion. Ang II type 1 (AT(1)) receptor-mediated uptake of circulating (125)I-Ang II was increased at 1 and 3 weeks in noninfarcted LV, and this uptake was the main cause of the transient elevation in Ang II levels in the noninfarcted LV at 1 week. Ang II levels and AT(1) receptor-mediated uptake of circulating Ang II were reduced in the infarct area at all time points. Coronary Ang I to Ang II conversion was unaffected by MI. Captopril and the AT(1) receptor antagonist eprosartan attenuated postinfarct remodeling, although both drugs increased cardiac Ang II production. Captopril blocked coronary conversion by >80% and normalized Ang II uptake in the noninfarcted LV. Eprosartan did not affect coronary conversion and blocked cardiac Ang II uptake by >90%. CONCLUSIONS: Both circulating and locally generated Ang II contribute to remodeling after MI. The rise in tissue Ang II production during angiotensin-converting enzyme inhibition and AT(1) receptor blockade suggests that the antihypertrophic effects of these drugs result not only from diminished AT(1) receptor stimulation but also from increased stimulation of growth-inhibitory Ang II type 2 receptors

Search for periodic signals in the dielectron and diphoton invariant mass spectra using 139 fb−1 of pp collisions at √s = 13 TeV with the ATLAS detector

A search for physics beyond the Standard Model inducing periodic signals in the dielectron and diphoton invariant mass spectra is presented using 139 fb−1 of √s =13 TeV pp collision data collected by the ATLAS experiment at the LHC. Novel search techniques based on continuous wavelet transforms are used to infer the frequency of periodic signals from the invariant mass spectra and neural network classifiers are used to enhance the sensitivity to periodic resonances. In the absence of a signal, exclusion limits are placed at the 95% confidence level in the two-dimensional parameter space of the clockwork gravity model. Model-independent searches for deviations from the background-only hypothesis are also performed

Massive haemorrhage at resternotomy after stent implantation in ventriculo-pulmonary shunt after Norwood procedure

The ventriculo-pulmonary shunt in hypoplastic left heart syndrome has become an alternative to the arterio-pulmonary shunt. We present a patient with a severe stenosis in the ventriculo-pulmonary shunt at the proximal anastomosis, for which emergency balloon dilatation and stent implantation was performed. The location of the stent in the shunt, leaving only a thin compressed infundibular myocardium directly beneath the sternum, predisposed to massive haemorrhage at resternotomy for bidirectional Glenn procedure. 2006 Published by European Association for Cardio-Thoracic Surgery. All rights reserved

Prophylactic treatment with alkaline phosphatase in cardiac surgery induces endogenous alkaline phosphatase release.

Introduction: Laboratory and clinical data have implicated endotoxin as an important factor in the inflammatory response to cardiopulmonary bypass. We assessed the effects of the administration of bovine intestinal alkaline phosphatase (bIAP), an endotoxin detoxifier, on alkaline phosphatase levels in patients undergoing coronary artery bypass grafting. Methods: A total of 63 patients undergoing coronary artery bypass grafting were enrolled and prospectively randomized. Bovine intestinal alkaline phosphatase (n=32) or placebo (n=31) was administered as an intravenous bolus followed by continuous infusion for 36 hours. The primary endpoint was to evaluate alkaline phosphatase levels in both groups and to find out if administration of bIAP to patients undergoing CABG would lead to endogenous alkaline phosphatase release. Results: No significant adverse effects were identified in either group. In all the 32 patients of the bIAP-treated group, we found an initial rise of plasma alkaline phosphatase levels due to bolus administration (464.27±176.17 IU/L). A significant increase of plasma alkaline phosphatase at 4-6 hours postoperatively was observed (354.97±95.00 IU/L) as well. Using LHA inhibition, it was shown that this second peak was caused by the generation of Tissue Non Specific Alkaline Phosphatase (TNSALP-type alkaline phosphatase). Conclusions: Intravenous bolus administration plus 8 hours continuous infusion of alkaline phosphatase in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass results in endogenous alkaline phosphatase release. This endogenous alkaline phosphatase may play a role in the immune defense system

The role of collagen cross-links in biomechanical behavior of human aortic heart valve leaflets: Relevance for tissue engineering

Tissue Engineering The Role of Collagen Cross-Links in Biomechanical Behavior of Human Aortic Heart Valve Leaflets—Relevance for Tissue Engineering -------------------------------------------------------------------------------- To cite this paper: Angelique Balguid, Mirjam P. Rubbens, Anita Mol, Ruud A. Bank, Ad J.J.C. Bogers, Jorge P. van Kats, Bas A.J.M. de Mol, Frank P.T. Baaijens, Carlijn V.C. Bouten. Tissue Engineering. 2007, 13(7): 1501-1511. doi:10.1089/ten.2006.0279. -------------------------------------------------------------------------------- Angelique Balguid, M.Sc. Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands. Dutch Polymer Institute, Eindhoven University of Technology, Eindhoven, The Netherlands. Mirjam P. Rubbens, M.Sc. Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands. Anita Mol, Ph.D. Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands. Ruud A. Bank, Ph.D. Gaubius Laboratory TNO Prevention and Health, Leiden, The Netherlands. Ad J.J.C. Bogers, M.D., Ph.D. Rotterdam Heart Valve Bank, Erasmus University Medical Center, Rotterdam, The Netherlands. Department of cardio-thoracic surgery, Erasmus University Medical Center, Rotterdam, The Netherlands. Jorge P. van Kats, Ph.D. Rotterdam Heart Valve Bank, Erasmus University Medical Center, Rotterdam, The Netherlands. Bas A.J.M. de Mol, M.D., Ph.D. Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands. Department of Cardiopulmonary Surgery, Academic Medical Center, Amsterdam, The Netherlands. Frank P.T. Baaijens, Ph.D. Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands. Carlijn V.C. Bouten, Ph.D. Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands. A major challenge in tissue engineering of functional heart valves is to determine and mimic the dominant tissue structures that regulate heart valve function and in vivo survival. In native heart valves, the anisotropic matrix architecture assures sustained and adequate functioning under high-pressure conditions. Collagen, being the main load-bearing matrix component, contributes significantly to the biomechanical strength of the tissue. This study investigates the relationship between collagen content, collagen cross-links, and biomechanical behavior in human aortic heart valve leaflets and in tissue-engineered constructs. In the main loading direction (circumferential) of native valve leaflets, a significant positive linear correlation between modulus of elasticity and collagen cross-link concentration was found, whereas no correlation between modulus of elasticity and collagen content was found. Similar findings were observed in tissue-engineered constructs, where cross-link concentration was higher for dynamically strained constructs then for statically cultured controls. These findings suggest a dominant role for collagen cross-links over collagen content with respect to biomechanical tissue behavior in human heart valve leaflets. They further suggest that dynamic tissue straining in tissue engineering protocols can enhance cross-link concentration and biomechanical function

The role of collagen cross-links in biomechanical behavior of human aortic heart valve leaflets: Relevance for tissue engineering

Tissue Engineering The Role of Collagen Cross-Links in Biomechanical Behavior of Human Aortic Heart Valve Leaflets—Relevance for Tissue Engineering -------------------------------------------------------------------------------- To cite this paper: Angelique Balguid, Mirjam P. Rubbens, Anita Mol, Ruud A. Bank, Ad J.J.C. Bogers, Jorge P. van Kats, Bas A.J.M. de Mol, Frank P.T. Baaijens, Carlijn V.C. Bouten. Tissue Engineering. 2007, 13(7): 1501-1511. doi:10.1089/ten.2006.0279. -------------------------------------------------------------------------------- Angelique Balguid, M.Sc. Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands. Dutch Polymer Institute, Eindhoven University of Technology, Eindhoven, The Netherlands. Mirjam P. Rubbens, M.Sc. Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands. Anita Mol, Ph.D. Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands. Ruud A. Bank, Ph.D. Gaubius Laboratory TNO Prevention and Health, Leiden, The Netherlands. Ad J.J.C. Bogers, M.D., Ph.D. Rotterdam Heart Valve Bank, Erasmus University Medical Center, Rotterdam, The Netherlands. Department of cardio-thoracic surgery, Erasmus University Medical Center, Rotterdam, The Netherlands. Jorge P. van Kats, Ph.D. Rotterdam Heart Valve Bank, Erasmus University Medical Center, Rotterdam, The Netherlands. Bas A.J.M. de Mol, M.D., Ph.D. Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands. Department of Cardiopulmonary Surgery, Academic Medical Center, Amsterdam, The Netherlands. Frank P.T. Baaijens, Ph.D. Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands. Carlijn V.C. Bouten, Ph.D. Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands. A major challenge in tissue engineering of functional heart valves is to determine and mimic the dominant tissue structures that regulate heart valve function and in vivo survival. In native heart valves, the anisotropic matrix architecture assures sustained and adequate functioning under high-pressure conditions. Collagen, being the main load-bearing matrix component, contributes significantly to the biomechanical strength of the tissue. This study investigates the relationship between collagen content, collagen cross-links, and biomechanical behavior in human aortic heart valve leaflets and in tissue-engineered constructs. In the main loading direction (circumferential) of native valve leaflets, a significant positive linear correlation between modulus of elasticity and collagen cross-link concentration was found, whereas no correlation between modulus of elasticity and collagen content was found. Similar findings were observed in tissue-engineered constructs, where cross-link concentration was higher for dynamically strained constructs then for statically cultured controls. These findings suggest a dominant role for collagen cross-links over collagen content with respect to biomechanical tissue behavior in human heart valve leaflets. They further suggest that dynamic tissue straining in tissue engineering protocols can enhance cross-link concentration and biomechanical function