Coupling between myocardial oxygen consumption and mechanics in patients with dilative cardiomyopathy. Influence of vasodilation and positive inotropism.
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Cardiomyopathy, Dilated↗
Biomedical subjects
M von Herrath
Publications and source records attributed to M von Herrath.
Sensitivity of fructose-1,6-biphosphatase from yeast, liver and skeletal muscle to fructose-2,6-biphosphate and 5'-adenosine monophosphate.
As a prerequisite for future studies on the possible effect of sulphite, an anti-microbial agent, on gluconeogenesis in yeast, a comparative study of fructose-1,6-bisphosphatase (FBPase), a key enzyme of gluconeogenesis, from yeast, liver and skeletal muscle is reported. In contrast to FBPase from yeast or liver, FBPase from skeletal muscle is approximately 1000-fold more sensitive to inhibition by 5' adenosine monophosphate and 30 to 250-fold less sensitive to inhibition by fructose-2,6-bisphosphate. The kinetic properties of the FBPases, determined by the ratios R(Mg2+/Mn2+) and R (pH 7/9) of the enzyme activities, measured at 10 mM Mg2+ and 2 mM Mn2+ and at pH 7.0 and 9.0, respectively, show a drastic difference between the skeletal muscle and the yeast or liver enzymes. The data support the idea that the enzymes from yeast and liver function in gluconeogenesis, whereas the enzyme from skeletal muscle is involved in other biological functions.
Adenosine Monophosphate↗
Comparison of human brain and liver glutamate dehydrogenase cDNAS.
In order to investigate suggestions that more than one glutamate dehydrogenase (GDH) gene may be active in humans, seven human brain and seventeen human liver GDH cDNAs were isolated by probing with a 590 base cDNA from the coding region of human brain GDH. No sequence heterogeneity was revealed among any of the cDNAs by an oligonucleotide binding assay, nor did any cDNA appear to encode a hexapeptide contained in a published amino acid sequence of human liver GDH. Homologous regions of three liver and three brain cDNAs had identical sequences over more than 2 kb, including 3' nontranslated regions. This suggests that identical GDH mRNAs are present in human brain and human liver. Although only one gene appears to be expressed, human genomic DNA blots show a pattern of hybridization consistent with the existence of more than one GDH gene.
Amino Acid Sequence↗
Acute effects of nitrates on left ventricular performance and energetics.
Left ventricular myocardial performance and efficiency were analyzed on the basis of two new energetic parameters in patients with coronary heart disease. The myocardial energy consumed during one cardiac cycle is related on the one hand to the work performed (E1) and on the other to the stress-time integral (E2). E1 was obtained by analysis of the pressure-volume integral divided by the left ventricular muscle mass. E2 was obtained as follows: The stress-time integral was analyzed from pressure-volume data and wall thickness using an ellipsoidal calculation model. In order to transfer the stress-time integral into energy units, the value is multiplied by a constant factor which was obtained experimentally in myothermal studies. In patients with coronary heart disease, a single dose of nitroglycerin (1.6 mg s.l.) reduced the total energy sigma (E1 + E2) from 6.1 mcal/g to 4.7 mcal/g (n = 10; P less than 0.01). The efficiency of myocardial contraction (E1/sigma (E1 + E2] was not changed significantly. These data explain quantitatively the beneficial effect of preload and afterload reduction due to nitroglycerin.
Energy Metabolism↗
Myocardial performance and efficiency as assessed by energetic parameters derived from pressure-volume relations and wall thickness in human ventricles.
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Aortic Valve↗
Modification of yeast fructose-1,6-bisphosphatase.
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Adenosine Monophosphate↗
Oxidative inactivation of yeast fructose-1,6-bisphosphatase.
Active, non-phosphorylated fructose-1,6-bisphosphatase from yeast is partially inactivated by two different mixed-function oxidation systems: the ascorbate-FeC13-02 system described by Levine (Levine, R. (1983) J. Biol. Chem. 258, 11823-11827) and the NADH oxidase-NADH-FeC13-O2 system described by Fucci et al. (Fucci, L., Oliver, C.N., Coon, M.J., and Stadtman, E.R. (1983) Proc. Natl. Acad. Sci. 80, 1521-1525). Fructose-2,6-bisphosphate (1 microM) or histidine (10 mM) partially protect from oxidative inactivation. The inactivation is characterized by the following changes in the kinetic properties of fructose-1,6-bisphosphatase: decrease of the ratio of activity at pH 7 to that at pH 9 and decrease of the ratio of activity with 10 mM Mg2+ to that with 2 mM Mn2+. These changes of the kinetic properties are very similar to the ones previously observed following phosphorylation (Holzer, H. (1984) in "Enzyme regulation by reversible phosphorylation - further advances" (P. Cohen, ed.) pp. 143-154, Elsevier Science publisher) and limited proteolysis of fructose-1,6-bisphosphatase with yeast proteinase B (Pohlig, G., Schäfer, W., v. Herrath, M. and Holzer, H. (1984) in "Current topics in cellular regulation" (S. Shaltiel and P. Boon Chock, eds.) in press).
Ascorbic Acid↗