Heart failure: clinical aspects from basic research. Introduction.
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Diastole↗
Biomedical subjects
V Regitz-Zagrosek
Publications and source records attributed to V Regitz-Zagrosek.
Genetic polymorphisms of the angiotensin II type 1 (AT1) receptor gene.
Numerous essential, physiological effects on the cardiovascular system are attributable to angiotensin II (Ang II). Because of this we can assume that genetic changes in the specific receptor of Ang II (Ang II type 1 receptor gene, AT1) play a decisive role in the occurrence of cardiovascular disease associated with blood pressure regulation, vascular tone, cardiac and vascular growth process. To test this hypothesis, we examined the presence of polymorphisms within the coding region of the AT1 gene using polymerase chain reaction (PCR) and subsequent non-radioactive sequencing of samples from a control group with no previous history of cardiovascular complaint in individuals or immediate family. Using the Taq-sequencing procedure we found polymorphic sites, especially in the 5' region of the gene (base pair positions 9, 16, 87, 133, 186), two of which led to an exchange of the amino acid (amino acid 6: Ser<==>Pro, amino acid 45: Gly<==>Arg). Together with the silent polymorphism at base pair position 573, which our group established previously, an additional polymorphism in the 3' region of the gene was discovered. This, however, did not confer any changes in amino acid sequence. In a preliminary study we found no association between the distribution of the C/T573 polymorphic site and cardiovascular disease, such as essential hypertension (n = 20) coronary artery disease (n = 16) hypertrophic cardiomyopathy (n = 12) or dilated cardiomyopathy (n = 21). Further studies will be needed to determine to what extent the polymorphisms described are associated with cardiovascular disease.
Amino Acid Sequence↗
Characterization of myocardial protein composition in dilated cardiomyopathy by two-dimensional gel electrophoresis.
In order to identify alterations in the myocardial protein pattern that characterize dilated cardiomyopathy (DCM), we compared, by two-dimensional gel electrophoresis, right atrial protein patterns from five patients with DCM and four with normal left ventricular function (two gels per patient). Using computer assisted analysis (PDQUEST, 4.1) we found reproducible protein patterns in the 18 gels (23 x 30 cm, pH 4-9, molecular weight 10-150 kDa). In the two gels from the same patient, 91% of proteins were identical in their position in the pattern and the relative intensities of these protein species correlated with r = 0.85. Three hundred and two +/- 50 protein species were found in several gels, 186 in all 18 gels. Seven proteins in the DCM group were decreased in their relative intensity by > 100%, six were increased by > 100%. Significant quantitative differences between DCM and control patients were found for 25 protein species. Based on seven external marker proteins, a pH and molecular weight value could be calculated for each protein. So far, 30 protein species have been identified by antibodies, amino acid analysis or sequencing procedures. From the 25 proteins that are significantly different between DCM and controls, three have been identified. Expression of the mitochondrial creatine kinase and alpha cristallin B chain was significantly increased in DCM; the malate dehydrogenase family was also significantly decreased in DCM. Two-dimensional electrophoresis appears to be a powerful method for the detection of disease-associated alterations in the myocardial protein pattern.
Adult↗
Myocardial cyclic AMP and norepinephrine content in human heart failure.
Impaired production of myocardial cyclic adenosine monophosphate (cAMP) is thought to contribute to contractile dysfunction in end stage heart failure, but myocardial cAMP content has not yet been evaluated in heart failure patients in comparison with controls. We therefore measured the myocardial content of cAMP by radioimmunoassay in endomyocardial biopsies from patients in different stages of heart failure and in controls and correlated it with biochemical and functional parameters. The myocardial content of norepinephrine was determined by HPLC in the same biopsies in order to assess if the myocardium studied was affected by heart failure. Myocardial cAMP (in fmol.microgram-1 non-collagen protein) in 20 patients with heart failure (LVEF: 27 +/- 8%, cAMP: 5.8 +/- 2.0) was unchanged in comparison with eight controls (LVEF: 64 +/- 4.7%, cAMP, 4.9 +/- 2.1). In contrast, myocardial norepinephrine (in pg.microgram-1 non-collagen protein) in the same biopsies was significantly reduced in heart failure (4.0 +/- 3.0) in comparison with the same controls (11.5 +/- 3.0, P < 0.0002). Plasma cAMP in 20 heart failure patients (22.0 +/- 4.2 pmol.l-1) was not different from controls(22.0 +/- 7.8), whereas plasma norepinephrine was increased (heart failure: 460 +/- 257 pg.ml-1, controls 182 +/- 49, P < 0.001). Myocardial cAMP levels are indistinguishable from controls in human heart failure and therefore do not contribute to a further characterization of the cardiac adrenergic system in these patients. This is most likely due to the impossibility of obtaining biopsies with truly unstimulated adenylyl cyclase activity.
Adult↗
Regulation of the angiotensin receptor subtypes in cell cultures, animal models and human diseases.
With the development of subtype specific angiotensin II (Ang II) receptor antagonists and their introduction into the treatment of heart failure and hypertension, the regulation of the Ang II receptor with its subtypes AT1 and Ang T2 gains clinical importance. In cell cultures, the number of surface AT1 is clearly down-regulated by Ang II exposure. Down-regulation can be due to reversible internalization, to phosphorylation and to reduced synthesis and involves protein kinase C and phospholipase C mediated pathways. In this respect, the AT1 behaves as a typical G-protein coupled receptor. Aldosterone, cAMP, norepinephrine and extracellular glucose concentrations can contribute to AT1 regulation. There are very few data regarding the regulation of the subtype AT2, indicating modulation by a number of growth factors and by Ang II. In whole animal models receptor regulation deviates partially from cell cultures. In the rat, the two subtypes AT1A and AT1B are differentially regulated and the expression of subtypes is organ specific. In most experiments, including our own experiences, the AT1, in the adrenals was up-regulated by Ang II infusion and down-regulated by angiotensin converting enzyme inhibitors (ACEI) or Ang II receptor antagonists. Differing effects were observed in other organs. In humans, a number of studies seeking an association between Ang II levels, Ang II receptor regulation and physiological events have been conducted in platelets. In pregnant women, a negative correlation between plasma Ang II levels and Ang II binding and an association between receptor regulation and pregnancy-induced hypertension has been described.(ABSTRACT TRUNCATED AT 250 WORDS)
Angiotensin-Converting Enzyme Inhibitors↗
MnlI polymorphism for the AGTR1 gene.
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Angiotensin I↗
Dilated cardiomyopathy: computer-assisted analysis of endomyocardial biopsy protein patterns by two-dimensional gel electrophoresis.
In order to identify disease-associated alterations in the myocardial protein patterns in dilated cardiomyopathy, we used 2-dimensional gel electrophoresis to analyse the proteins of endomyocardial biopsies from patients and controls. Proteins (150 micrograms) from biopsies (1-3 mg wet weight) were first separated by isoelectric focusing, then applied to large 2-dimensional gels. A computer-assisted system (PDQUEST) was used for spot detection, quantification and comparison of 2-dimensional protein patterns. From a single endomyocardial biopsy about 1000 different protein species were resolved. The spot pattern was influenced by the concentration of protein during sample preparation, by the amount of protein loaded onto the gels and by the development time of silver staining. Variances of spot position in the first and second dimension and in the long diagonals were less than 5%. Coefficients of variance for the spot quantities in 8 gels were 16 +/- 8%. Contaminating blood proteins could be identified in the biopsy patterns. Computer-assisted comparison between cardiomyopathy (n = 5) and controls (n = 5) over the whole gel revealed that 55 protein spots were increased 100%, 27 protein spots decreased 100%. Four proteins showed significant quantitative differences between the cardiomyopathic hearts and controls. Fourteen proteins were identified by amino acid analysis or microsequencing. An isoelectric point and molecular mass grid was laid over the whole gel based on these identified protein species, resulting in approximate isoelectric point values and molecular masses for all other protein species. Thus, myocardial 2-dimensional protein patterns obtained from endomyocardial biopsies can be used for the characterization of cardiac diseases.
Adult↗
Regulation of beta-adrenergic receptors on endothelial cells in culture.
This study aimed to determine the density of vascular beta-adrenergic receptors in cultured endothelial cells and to study the regulation of endothelial receptors after exposure to catecholamines and the ACE inhibitors, lisinopril and ramiprilat. Membranes from bovine aortic endothelial cells (BAEC) and bovine pulmonary artery endothelial cells (BPAEC) showed saturable binding of the radioligand [125I]iodocyanopindolol (ICYP). The beta-receptor density and binding affinity were comparable in both types of endothelial cells. Isoproterenol induced significant down-regulation of beta-receptors (-50%; P < 0.01). Incubation (24h) with the ACE inhibitors lisinopril 10(-5) M (+28.8%; P < 0.05) and ramiprilat 10(-5) M (+33.7%, P < 0.09) augmented the beta-receptor density in BAEC, but lower ACE inhibitor doses had no affect. Incubation with lisinopril 10(-5) M for 24 h resulted in significantly lower cAMP baseline levels, but did not affect cAMP concentrations after stimulation with isoproterenol. These results indicate that down-regulation of endothelial beta-receptors occurs during prolonged exposure to beta-stimulation, and that high concentrations of ACE inhibitors may affect the density of endothelial beta-receptors.
Angiotensin-Converting Enzyme Inhibitors↗
A two-dimensional electrophoresis database of rat heart proteins.
More than 3000 myocardial protein species of Wistar Kyoto rat, an important animal model, were separated by high-resolution two-dimensional gel electrophoresis (2-DE) and characterized in terms of isoelectric point (pI) and molecular mass (Mr). Currently, the 2-DE database contains 64 identified proteins; forty-three were identified by peptide mass fingerprinting (PMF) using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), nine by exclusive comparison with other 2-DE heart protein databases, and in only 12 cases of 60 attempts N-terminal sequencing was successful. We used the Make2ddb software package downloaded from the ExPASy server for the construction of a rat myocardial 2-DE database. The Make2ddb package simplifies the creation of a new 2-DE database if the Melanie II software and a Sun workstation under Solaris are available. Our 2-DE database of rat heart proteins can be accessed at URL http://gelmatching.inf.fu-berlin.de/pleiss/2d.
Animals↗
Towards design and comparison of World Wide Web-accessible myocardial two-dimensional gel electrophoresis protein databases.
In addition to the recently published HEART-2DPAGE--a myocardial World Wide Web-accessible 2-DE gel protein database--the usage and installation of software tools are described with regard to the hard- and software environments. Further, access to the HEART-2DPAGE from other two-dimensional electrophoresis (2-DE) databases using name or accession code of a protein is now available. Moreover, database images, published in the myocardial HSC-2DPAGE and HEART-2DPAGE databases are compared. Using the warping tool of the common image processing system Khoros the database images are matched and added in order to visualize the effects of warping. The application of such image processing tools is aimed at improving the comparability of protein spot patterns of different gel images available through the net.
Computer Communication Networks↗