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  • 1
    Electronic Resource
    Electronic Resource
    Asymmetric redirection of flow through the heart (2000)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 404 (2000), S. 759-761 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Through cardiac looping during embryonic development, paths of flow through the mature heart have direction changes and asymmetries whose topology and functional significance remain relatively unexplored. Here we show, using magnetic resonance velocity mapping, the asymmetric redirection ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35008075
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  • 2
    Electronic Resource
    Electronic Resource
    Energy metabolism and mechanical recovery after cardioplegia in moderately hypertrophiedrats (1998)
    Springer
    Molecular and cellular biochemistry 180 (1998), S. 137-143 
    Details
    ISSN: 1573-4919
    Keywords: myocardial protection ; hypertrophy ; phosphocreatine ; cardioplegia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract It is well established that severe hypertrophy induces metabolic and structural changes in the heart which result in enhanced susceptibility to ischemic damage during cardioplegic arrest while much less is known about the effect of cardioplegic arrest on moderately hypertrophied hearts. The aim of this study was to elucidate the differences in myocardial high energy phosphate metabolism and in functional recovery after cardioplegic arrest and ischemia in mildly hypertrophied hearts, before any metabolic alterations could be shown under baseline conditions. Cardiac hypertrophy was induced in rats by constriction of the abdominal aorta resulting in 20% increase in heart weight/body weight ratio (hypertrophy group) while sham operated animals served as control. In both groups, isolated hearts were perfused under normoxic conditions for 40 min followed by infusion of St.Thomas' Hospital No. 1 cardioplegia and 90 min ischemia at 25øC with infusions of cardioplegia every 30 min. The changes in ATP, phosphocreatine (PCr) and inorganic phosphate (Pi) were followed by31 P nuclear magnetic resonance (NMR) spectroscopy. Systolic and diastolic function was assessed with an intraventricular balloon before and after ischemia. Baseline concentrations of PCr, ATP and Pi as well as coronary flow and cardiac function were not different between the two groups. However, after cardioplegic arrest PCr concentration increased to 61.8 ± 4.9 μmol/g dry wt in the control group and to 46.3 ± 2.8 μmol/g in hypertrophied hearts. Subsequently PCr, pH and ATP decreased gradually, concomitant with an accumulation of Pi in both groups. PCr was transiently restored during each infusion of cardioplegic solution while Pi decreased. PCr decreased faster after cardioplegic infusions in hypertrophied hearts. The most significant difference was observed during reperfusion: PCr recovered to its pre-ischemic levels within 2 min following restoration of coronary flow in the control group while similar recovery was observed after 4 min in the hypertrophied hearts. A greater deterioration of diastolic function was observed in hypertrophied hearts. Moderate hypertrophy, despite absence of metabolic changes under baseline conditions could lead to enhanced functional deterioration after cardioplegic arrest and ischemia. Impaired energy metabolism resulting in accelerated high energy phosphate depletion during ischemia and delayed recovery of energy equilibrium after cardioplegic arrest observed in hypertrophied hearts could be one of the underlying mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006807510648
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  • 3
    Electronic Resource
    Electronic Resource
    Hyperthyroidism increases adenosine transport and metabolism in the rat heart (1995)
    Springer
    Molecular and cellular biochemistry 143 (1995), S. 143-149 
    Details
    ISSN: 1573-4919
    Keywords: adenosine ; adenosine transport ; hyperthyroidism ; cardiomyocytes ; membrane-5′-nucleotidase ; adenine nucleotides ; creatine compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Hyperthyroidism induces a number of metabolic and physiological changes in the heart including hypertrophy, increase in inotropic status, and alterations of myocardial energy metabolism. The effects of hyperthyroidism on adenosine metabolism which is intimately involved in the control of many aspects of myocardial energetics, have not been clarified. The aim of this study was thus to evaluate the potential role of adenosine in the altered physiology of the hyperthyroid heart. Transport of adenosine was studied in cardiomyocytes isolated from hyperthyroid and euthyroid rats. Activities of different enzymes of purine metabolism were studied in heart homogenates and concentrations of nucleotide and creatine metabolites were determined in hearts freeze-clampedin situ. Both transport of adenosine into cardiomyocytes and the rate of intracellular phosphorylation were higher in the hyperthyroid rat. At 10 μM concentration, adenosine transport rates were 275 and 197 pmol/min/mg protein in hyperthyroid and euthyroid cardiomyocytes respectively whilst rates of adenosine phosphorylation were 250 and 180 pmol/min/mg prot. An even more pronounced difference was observed if values were expressed per number of cells due to cardiomyocyte enlargement. Hyperthyroidism was associated with a 20% increase in adenosine kinase, 30% decrease in membrane 5′-nucleotidase and 15% decrease in adenosine deaminase activities measured in heart homogenates. In addition there was a substantial depletion in the total creatine pool from 63.7 to 41.6 μmol/g dry wt, a small decrease in the adenylate pool (from 27.2 to 24.3 μmol/g dry wt) and an elevation of the guanylate pool (from 1.22 to 1.36). These results show that adenosine transport and phosphorylation capacity is enhanced in hyperthyroidism. These may represent a feedback response to accelerated nucleotide degradation suggested in turn by the decrease in steady-state adenine nucleotide content. The decrease in membrane 5′-nucleotidase activity may represent another feature of hypertrophy where the cell surface to cell volume ratio decreases. The decrease of this activity may modify the conversion of extracellular nucleotides to adenosine and consequently reduce endogenous cardioprotection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01816948
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of nucleoside transport inhibitors and adenine/ribose supply on ATP concentration and adenosine production in cardiac myocytes (1998)
    Springer
    Molecular and cellular biochemistry 180 (1998), S. 193-199 
    Details
    ISSN: 1573-4919
    Keywords: adenosine ; nucleoside transport inhibitors ; heart metabolism ; adenine nucleotides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Adenosine plays an important role in protection of the heart before, during and after ischemia. Nucleoside transport inhibitors (NTI) increase adenosine concentration without inducing ischemia by preventing its uptake and metabolism in cardiac cells. However, prolonged effects of nucleoside transport inhibitors on adenosine and nucleotide metabolism and its combined effect with nucleotide precursors has not been established in cardiomyocytes. The aim of this study was to investigate the effect of two nucleoside transport inhibitors, dipyridamole (DIPY) and nitrobenzylthioinosine (NBTI) alone or combined with adenine and ribose on adenosine production and ATP content in cardiomyocytes. Rat cardiomyocytes were isolated using collagenase perfusion technique. Isolated cell suspensions were incubated for up to 480 min with different substrates and inhibitors as follows: (1) control; (2) 100 μM adenine and 2.5 mM ribose; (3) 10 μM DIPY; (4) 1 μM NBTI; (5) DIPY, adenine and ribose and (6) NBTI, adenine and ribose. Five μM EHNA (erythro-9(2-hydroxy-3-nonyl)adenine, an inhibitor of adenosine deaminase) was added to all incubations. After incubation, extracts of myocyte suspension were analysed by HPLC for adenine nucleotides and metabolite concentrations. ATP content decreased in cardiomyocytes after 8 h of incubation with DIPY, while no change was observed with NBTI or without inhibitors. Adenosine concentration increased with both DIPY and NBTI. In the presence of adenine and ribose an elevation in ATP concentration was observed, but no significant change in adenosine content. In the presence of DIPY or NBTI together with adenine and ribose, an enhancement in cardiomyocyte ATP concentration was observed together with an increase in adenosine content. This increase in adenosine production was especially prominent with DIPY. In conclusion, dipyridamole causes a decrease in ATP concentration in isolated cardiomyocytes by mechanisms other than nucleoside transport inhibition. Addition of adenine/ribose with dipyridamole prevents the depletion of ATP. Combination of adenine/ribose with nucleoside transport inhibitors may also further enhance adenosine concentration and thus, could be more effective as pharmacological agents for treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006880132030
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  • 5
    Electronic Resource
    Electronic Resource
    Reduced purine catabolite production in the postischemic rat heart: a31P NMR assessment of cytosolic metabolites (1994)
    Springer
    Magnetic resonance materials in physics, biology and medicine 2 (1994), S. 417-420 
    Details
    ISSN: 1352-8661
    Keywords: 31P-NMR ; ischemia ; energy metabolism ; purine release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics
    Notes: Abstract Ischemia can cause release of adenosine and purine catabolites from the heart, through the breakdown of ATP. If repeated periods of ischemia are induced, the efflux of purines is markedly reduced, although it is not clear if this is beneficial for the long-term survival of the heart. We have investigated changes in high-energy phosphates and purine release in the isolated perfused rat heart using31P NMR spectroscopy and high-performance liquid chromatography. Hearts were subjected to one of the following protocols: Group A—1 min of total global ischemia (TGI) after 40 min, 60 min, and 85 min of perfusion (a total of 3 × 1 min ischemia); Group B—1 min of TGI after 40 min of perfusion, 10 min of TGI after 50 min of perfusion, and a final 1 min of TGI after 85 min of perfusion. The profile of high-energy phosphate metabolites, Pi accumulation and purine release was similar for each 1-min period of TGI in Group A, whereas phosphocreatine content was increased and ATP content reduced by an extended period of TGI in Group B, leading to a less severe acidosis and purine efflux in the final 1 min of TGI at 85 min of perfusion. In conclusion, the reduced purine release observed in Group B may be related to the preischemic ATP pool size and accessibility and the increased myocardial energy reserve in the form of phosphocreatine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01705287
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  • 6
    Electronic Resource
    Electronic Resource
    Electrophoretic and computer analysis of skeletal muscle used for cardiac assistance (1991)
    Weinheim : Wiley-Blackwell
    Electrophoresis 12 (1991), S. 570-575 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Skeletal muscle has an inherent plasticity which allows it to undergo fibre type transformation when induced by a specific stimulus. Electrical stimulation has been used here to induce transformation of a predominantly fast type skeletal muscle towards a slow, more fatigue-resistant phenotype, which is more suitable for use in long-term cardiac assistance. Muscle samples from animals electrically stimulated for periods up to 6 months have been analysed by electrophoresis for myosin heavy chain (MHC) and myosin light chain (MLC) fast and slow isoforms. Densitometry and computer analysis have been used to determine the pattern of transformation of the different myosin subunits over this time period. MHC and MLC 2 fast to slow isoform switching preceded that of the alkali light chains (MLC1 and MLC3). After 3 months of stimulation the MHC slow isoform was found to have doubled in concentration relative to the unstimulated control muscle and by 4 months accounted for almost 50 % of the total MW content. The slow isoform accounted for 75 % of the MLC 2 after 4 months of stimulation. The protein products of mRNA isolated from stimulated muscle samples, translated in vitro and separated by electrophoresis, showed that transformation at the mRNA level preceded that at the protein level. By 2-4 weeks of stimulation MLC2 slow isoform mRNA represented over 60 % of the total MLC2 mRNA population. An understanding of the molecular structure of muscle during transformation provides insight into its haemodynamic performance in cardiac assistance.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150120716
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  • 7
    Electronic Resource
    Electronic Resource
    The human myocardial two-dimensional gel protein database: Update 1994 (1994)
    Weinheim : Wiley-Blackwell
    Electrophoresis 15 (1994), S. 1459-1465 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: An updated human heart protein two-dimensional electrophoresis (2-DE) database is presented. The database, which contains some 1388 protein spots characterised in terms of Mr and pI, has been analysed further by Western immunoblotting and protein sequencing. From a total of 103 protein spots analysed, 49 have been identified by immunoblotting and 32 have been identified by protein sequencing. A further six proteins have tentatively been assigned by comparison with the human heart 2-DE protein database of Jungblut et al. (Electrophoresis) 1994, 15, 685-607). This database is being used in studies of alterations in protein expression in the diseased and transplanted human heart.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.11501501209
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  • 8
    Electronic Resource
    Electronic Resource
    Evaluation of membranes used for electroblotting of proteins for direct automated microsequencing (1991)
    Weinheim : Wiley-Blackwell
    Electrophoresis 12 (1991), S. 342-348 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Protein purification and characterisation have been age-old problems for the biochemist. A new era has arisen with the advent of one- and two-dimensional gel electrophoresis and high sensitivity automated protein microsequencing. These two tools along with electroblotting have made it possible to separate and analyse complex protein mixtures. We studied six different membranes compatible with Edman degradation chemistry to determine their efficiencies at binding proteins electroblotted from one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Their overall blotting-sequencing properties were also evaluated. We found that the polyvinylidene difluoride-based membranes out-performed the glass-based and polypropylene-based membranes under our selec ted experimental conditions. The problems associated with electroblotting and microsequencing are discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150120505
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  • 9
    Electronic Resource
    Electronic Resource
    Electrophoretic analysis of electrically trained skeletal muscle (1992)
    Weinheim : Wiley-Blackwell
    Electrophoresis 13 (1992), S. 726-728 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Sheep latissimus dorsi muscle was electrically trained, thereby inducing fast-to-slow fibre-type transformation. Using a combination of one- and two-dimensional gel electrophoresis techniques with computer analysis, we have analysed altered expression of contractile protein isoforms at protein and mRNA level over a time course of electrical training extending to 5 months. Myosin heavy chain and regulatory myosin light chain analysis showed predominant expression of their slow isoforms (86% and 92%, respectively) after 3 months of training. At the same time point, however, tropomyosin analysis revealed that the slow isoform of the α-subunit accounted for 64% of the total α expression. Troponin T isoform switching proceeded more slowly over the same time course than tropomyosin and the thick filament proteins studied. Troponin T analysis revealed 5 fast and 2 slow isoforms in the sheep, of which the second slow isoform only became clearly visible after 5 months' training. At this time point the two slow isoforms were more predominant than their fast counterparts. This suggests that a wide heterogeneity of fast and slow isoform combinations are possible in the thin filament of skeletal muscle.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.11501301155
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  • 10
    Electronic Resource
    Electronic Resource
    Cardiac protein abnormalities in dilated cardiomyopathy detected by two-dimensional polyacrylamide gel electrophoresis (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2031-2042 
    Details
    ISSN: 0173-0835
    Keywords: Dilated cardiomyopathy ; Human heart ; Ischaemic heart disease ; Protein expression ; Two-dimensional polyacrylamide gel electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The aim of the investigation was to determine whether there are specific global quantitative and qualitative changes in protein expression in heart tissue from patients with dilated cardiomyopathy (DCM) compared with ischaemic heart disease and undiseased tissue. Two-dimensional (2-D) polyacrylamide gel electrophoresis and computer analysis was used to study protein alteration in DCM biopsy material (n=28) compared with donor heart biopsy samples (n=9) and explanted hearts from individuals suffering from ischaemic heart disease (IHD; n = 21). A total of 88 proteins displayed decreased abundance in DCM versus IHD material while five proteins had elevated levels in the DCM group (p〈0.01). The most prominent changes occurred in the contractile protein myosin light chain 2 and in a group of proteins identified as desmin. These changes do not appear to be artefactual degradation events occurring during sample processing. These proteins are not apparent in electrophoretic separations of vascular tissue or cultured endothelial cells, mesothelial cells or cardiac fibroblasts, which are clearly distinguishable from the 2-D protein patterns of whole heart and of isolated cardiac myocytes and do not appear to reflect variations in the cellular composition of biopsy samples. The different protein patterns observed in cardiomyopathy showed no obvious relationship with New York Heart Association (NYHA) functional class or haemodynamic parameters. The study has demonstrated significant alterations in quantitative protein expression in the DCM heart which would have serious implications for myocyte function. These changes might be explained by altered protease activity in DCM which could exacerbate contractile dysfunction in the failing heart.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191123
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