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001-es BibID:	BIBFORM015074
Első szerző:	Borbély Attila (kardiológus)
Cím:	Cardiomyocyte Stiffness in Diastolic Heart Failure / Borbély A., van der Velden J., Papp Z., Bronzwaer J. G. F., Edes I., Stienen G. J. M., Paulus W. J.
Dátum:	2005
ISSN:	0009-7322
Megjegyzések:	Heart failure with preserved left ventricular (LV) ejection fraction (EF) is increasingly recognized and usually referred to as diastolic heart failure (DHF). Its pathogenetic mechanism remains unclear, partly because of a lack of myocardial biopsy material. Endomyocardial biopsy samples obtained from DHF patients were therefore analyzed for collagen volume fraction (CVF) and sarcomeric protein composition and compared with control samples. Single cardiomyocytes were isolated from these biopsy samples to assess cellular contractile performance.METHODS AND RESULTS: DHF patients (n=12) had an LVEF of 71+/-11%, an LV end-diastolic pressure (LVEDP) of 28+/-4 mm Hg, and no significant coronary artery stenoses. DHF patients had higher CVFs (7.5+/-4.0%, P<0.05) than did controls (n=8, 3.8+/-2.0%), and no conspicuous changes in sarcomeric protein composition were detected. Cardiomyocytes, mechanically isolated and treated with Triton X-100 to remove all membranes, were stretched to a sarcomere length of 2.2 microm and activated with solutions containing varying [Ca2+]. Compared with cardiomyocytes of controls, cardiomyocytes of DHF patients developed a similar total isometric force at maximal [Ca2+], but their resting tension (F(passive)) in the absence of Ca2+ was almost twice as high (6.6+/-3.0 versus 3.5+/-1.7 kN/m2, P<0.001). F(passive) and CVF combined yielded stronger correlations with LVEDP than did either alone. Administration of protein kinase A (PKA) to DHF cardiomyocytes lowered F(passive) to control values.CONCLUSIONS: DHF patients had stiffer cardiomyocytes, as evident from a higher F(passive) at the same sarcomere length. Together with CVF, F(passive) determined in vivo diastolic LV dysfunction. Correction of this high F(passive) by PKA suggests that reduced phosphorylation of sarcomeric proteins is involved in DHF.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Circulation. - 111 : 6 (2005), p. 774-781. -
További szerzők:	Velden, Jolanda, van der Papp Zoltán (1965-) (kardiológus, élettanász) Bronzwaer, Jean G. F. Édes István (1952-) (kardiológus) Stienen, Ger J. M. Paulus, Walter J.
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001-es BibID:	BIBFORM010415
Első szerző:	Borbély Attila (kardiológus)
Cím:	Hypophosphorylation of the Stiff N2B titin isoform raises cardiomyocyte resting tension in failing human myocardium / Borbely, A., Falcao-Pires, I., van Heerebeek, L., Hamdani, N., Edes, I., Gavina, C., Leite-Moreira, A. F., Bronzwaer, J. G. F., Papp, Z., van der Velden, J., Stienen, G. J. M., Paulus, W. J.
Dátum:	2009
ISSN:	1524-4571 (Electronic)
Megjegyzések:	High diastolic stiffness of failing myocardium results from interstitial fibrosis and elevated resting tension (F(passive)) of cardiomyocytes. A shift in titin isoform expression from N2BA to N2B isoform, lower overall phosphorylation of titin, and a shift in titin phosphorylation from N2B to N2BA isoform can raise F(passive) of cardiomyocytes. In left ventricular biopsies of heart failure (HF) patients, aortic stenosis (AS) patients, and controls (CON), we therefore related F(passive) of isolated cardiomyocytes to expression of titin isoforms and to phosphorylation of titin and titin isoforms. Biopsies were procured by transvascular technique (44 HF, 3 CON), perioperatively (25 AS, 4 CON), or from explanted hearts (4 HF, 8 CON). None had coronary artery disease. Isolated, permeabilized cardiomyocytes were stretched to 2.2-microm sarcomere length to measure F(passive). Expression and phosphorylation of titin isoforms were analyzed using gel electrophoresis with ProQ Diamond and SYPRO Ruby stains and reported as ratio of titin (N2BA/N2B) or of phosphorylated titin (P-N2BA/P-N2B) isoforms. F(passive) was higher in HF (6.1+/-0.4 kN/m(2)) than in CON (2.3+/-0.3 kN/m(2); P<0.01) or in AS (2.2+/-0.2 kN/m(2); P<0.001). Titin isoform expression differed between HF (N2BA/N2B=0.73+/-0.06) and CON (N2BA/N2B=0.39+/-0.05; P<0.001) and was comparable in HF and AS (N2BA/N2B=0.59+/-0.06). Overall titin phosphorylation was also comparable in HF and AS, but relative phosphorylation of the stiff N2B titin isoform was significantly lower in HF (P-N2BA/P-N2B=0.77+/-0.05) than in AS (P-N2BA/P-N2B=0.54+/-0.05; P<0.01). Relative hypophosphorylation of the stiff N2B titin isoform is a novel mechanism responsible for raised F(passive) of human HF cardiomyocytes.
Tárgyszavak:	Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban Aged Biopsy Elasticity Female Heart Failure Humans Male Middle Aged Muscle Proteins Myocardium Myocytes, Cardiac Phosphorylation Protein Isoforms Protein Kinases Sarcomeres
Megjelenés:	Circulation Research. - 104 : 6 (2009), p. 780-786. -
További szerzők:	Falcao-Pires, Ines Heerebeek, Loek, van Hamdani, Nazha Édes István (1952-) (kardiológus) Gavina, Cristina Leite-Moreira, Adelino F. Bronzwaer, Jean G. F. Papp Zoltán (1965-) (kardiológus, élettanász) Velden, Jolanda, van der Stienen, Ger J. M. Paulus, Walter J.
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001-es BibID:	BIBFORM015092
Első szerző:	Velden, Jolanda, van der
Cím:	Functional effects of protein kinase C-mediated myofilament phosphorylation in human myocardium / van der Velden J., Narolska N. A., Lamberts R. R., Boontje N. M., Borbély A., Zaremba R., Bronzwaer J. G. F., Papp Z., Jaquet K., Paulus W. J., Stienen G. J.
Dátum:	2006
ISSN:	0008-6363
Megjegyzések:	In human heart failure beta-adrenergic-mediated protein kinase A (PKA) activity is down-regulated, while protein kinase C (PKC) activity is up-regulated. PKC-mediated myofilament protein phosphorylation might be detrimental for contractile function in cardiomyopathy. This study was designed to reveal the effects of PKC on myofilament function in human myocardium under basal conditions and upon modulation of protein phosphorylation by PKA and phosphatases.METHODS: Isometric force was measured at different [Ca(2+)] in single permeabilized cardiomyocytes from non-failing and failing human left ventricular tissue. Basal phosphorylation of myofilament proteins and the influence of PKC, PKA, and phosphatase treatments were analyzed by one- and two-dimensional gel electrophoresis, Western immunoblotting, and ELISA.RESULTS: Troponin I (TnI) phosphorylation at the PKA sites was decreased in failing compared to non-failing hearts and correlated well with myofilament Ca(2+) sensitivity (pCa(50)). Incubation with the catalytic domain of PKC slightly decreased maximal force under basal conditions, but not following PKA and phosphatase pretreatments. PKC reduced Ca(2+) sensitivity to a larger extent in failing (DeltapCa(50)=0.19+/-0.03) than in non-failing (DeltapCa(50)=0.08+/-0.01) cardiomyocytes. This shift was reduced, though still significant, when PKC was preceded by PKA, while PKA following PKC did not further decrease pCa(50). Protein analysis indicated that PKC phosphorylated PKA sites in human TnI and increased phosphorylation of troponin T, while myosin light chain phosphorylation remained unaltered.CONCLUSION: In human myocardium PKC-mediated myofilament protein phosphorylation only has a minor effect on maximal force development. The PKC-mediated decrease in Ca(2+) sensitivity may serve to improve diastolic function in failing human myocardium in which PKA-mediated TnI phosphorylation is decreased.
Tárgyszavak:	Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Cardiovascular Research. - 69 : 4 (2006), p. 876-887. -
További szerzők:	Narolska, Nadiya A. Lamberts, Regis Boontje, Nicky M. Borbély Attila (1978-) (kardiológus) Zaremba, Ruud Bronzwaer, Jean G. F. Papp Zoltán (1965-) (kardiológus, élettanász) Jaquet, Kornelia Paulus, Walter J. Stienen, Ger J. M.
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