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Query: UMLS:C0018801 (heart failure)
 72,216 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The expression of troponin T, a thin filament regulatory protein, was examined in normal and failing left ventricles. The samples were obtained from the hearts of patients with severe heart failure who were undergoing cardiac transplantation, and from normal adult hearts that could not be used for transplantation. Western blots of the myofibrillar proteins demonstrated two isoforms, troponin T 1 (TnT1) and troponin T 2 (TnT2). TnT2 is expressed at significantly higher levels in failing hearts (p less than 0.004). Western blots of two-dimension SDS-PAGE gels resolved two dominant spots of TnT1 and of TnT2 and several minor troponin T species. Alkaline phosphatase treatment markedly decreased the sizes of the two acidic spots while increasing the two more basic spots by a comparable amount. Myofibrillar ATPase activity had an inverse and negative linear relationship (r = 0.7, p less than 0.02) with the myofibrillar percentage of total troponin T comprised of TnT2. In that heart failure in these transplant patients had multiple bases, we propose that rather than a cause of heart failure, the disease-associated changes in troponin T isoform expression are an adaptation to abnormal myocardial function.
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PMID:Troponin T isoform expression in the normal and failing human left ventricle: a correlation with myofibrillar ATPase activity. 138 29

We review recent publications that use molecular and cellular biology to explore the diagnosis and treatment of cardiovascular diseases that have relevance to heart failure. Familial hypertrophic cardiomyopathy has now been shown to be due to mutations not only in the previously described beta myosin heavy chain gene, but also in the troponin T and alpha-tropomyosin genes, thus providing some symmetry to the idea that this is a molecular disease of the sarcomere. The basis for a type of familial dilated cardiomyopathy without substantial skeletal muscle involvement, caused by a mutation in the dystrophin gene, has been explored. However, by-and-large, the disease basis for most patients with dilated cardiomyopathy remains a molecular mystery. The role of a polymorphism in the angiotensin-converting enzyme gene was examined as a risk factor for a number of cardiovascular diseases. In animal models, the hypothesis that the devolution from hypertrophy to heart failure includes alterations in the molecular direction of extracellular matrix production gained some support. The experimental foundation was laid this year for the concept of and approach to cardiomyocytoplasty--the molecular and cellular treatment of heart failure by augmentation, repair, or replacement of cardiac myocytes--by experiments in cardiac gene transfer and transgenic animals. Gene causes and cures for restenosis after angioplasty garnered considerable attention. As we gain greater understanding of the molecular basis for disease, we will also have to increase our wisdom in the application of genetic testing.
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PMID:The molecular and cellular biology of heart failure. 761 72

Our own previous ultrastructural studies in human hearts with dilated cardiomyopathy and heart failure showed sarcomeric and cytoskeletal disarrangement. On the basis of these findings we tested the hypothesis that in cardiomyopathic failing hearts not only the sarcomere structure but also the organization and the amount of numerous contractile proteins are disturbed. Titin was included in this study because it is the elastic "third" filament of the sarcomere and also plays an important role as template for myosin and actin filaments in sarcomerogenesis. Human cardiac tissue obtained at the time of transplantation surgery was investigated using immunohistochemistry with monoclonal antibodies against titin, myosin, actin, tropomyosin, and troponin T. Additionally, isolated myocytes from rat or pig heart were used for the standardization of the localization pattern. In normal tissue, myosin and the thin filament complex showed a regular cross striation that was wider in myosin staining than for actin, troponin T, and tropomyosin corresponding with the different width of the A and I bands in the sarcomere. Titin localization in normal human and animal myocardium showed a regular cross striation pattern. In diseased cardiac tissue titin fluorescence intensity was reduced and frequently disorganization or almost complete loss of titin from many myocytes were present. Severe abnormalities of contractile proteins consisting of disarrangement or lack of filaments were also observed. Double staining procedures showed that in the same myocyte defects of the contractile apparatus were accompanied by a simultaneous reduction of titin indicating that the "third" sarcomeric filament system is involved in heart failure. Abnormalities of titin expression may be especially important because titin significantly influences sarcomeric elastic behaviour and is necessary as template for the organization of newly synthesized myosin and actin filaments. The loss of titin may contribute to the altered compliance in failing hearts. It is concluded that disorganization and loss of titin, myosin, and the thin filament complex are severe in the failing human heart because of dilated cardiomyopathy and that these changes may represent several of the most important components of the structural correlate of reduced cardiac function.
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PMID:Altered expression of titin and contractile proteins in failing human myocardium. 786 90

To examine the molecular basis of hypertrophied heart failure, we investigated the changes in cardiac contractile regulatory proteins. The guinea pigs were subjected to chronic pressure overload with aortic banding to induce ventricular hypertrophy, and in-situ pressure-volume relations were recorded together with biochemical characterizations to ascertain the contractile modifications. Immunoblots of left and right ventricular samples revealed four distinct troponin T isoforms, which underwent alterations during hypertrophy. The higher molecular weight bands TnT1 and TnT2 shifted towards the lower molecular weight isoforms TnT3 and TnT4. For TnI, a single prominent band was detected, whose intensity also increased with pump failure. The findings provide the first direct evidence of TnT and TnI shifts in an experimentally induced hypertrophied heart failure and has novel mechanistic implications for the future studies.
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PMID:Shifts in contractile regulatory protein subunits troponin T and troponin I in cardiac hypertrophy. 803 37

In recent years, the striking development of molecular biology and molecular genetic has brought completely new insights into the understanding of heart failure. Two aspects for which significant progress has been made in 1995 are discussed in this review: the genetic mechanisms of inherited cardiomyopathies and the molecular basis of heart failure due to chronic hemodynamic overload. In familial hypertrophic cardiomyopathy, a novel disease gene was found. It encodes myosin binding protein C, whose structure and function are poorly understood. Contractile deficits associated with the myosin mutations were demonstrated, and all this strengthened the hypothesis that hypertrophy is a compensatory mechanism that occurs in presence of a sarcomeric defect. These studies have important prognostic and clinical implications, but new and unexpected concerns have arisen, because a widespread difference in phenotype can be seen in patients harboring similar genotypes. In familial dilated cardiomyopathy, the main findings were the identification of four disease loci, but the genes are still unknown. With respect to the consequences of chronic hemodynamic overload on myocyte function and phenotype, recent data gave rise to lively discussions in the fields of reexpression of fetal troponin T isoforms and of decreased function and expression of the sarco(endo)plasmic reticulum Ca2+ ATPase in the failing human heart; at the moment it is difficult to draw definitive conclusions. Interestingly, three new concepts emerged in the understanding of the pathogenesis of heart failure: the increased contribution of the Na(+)-Ca2+ exchange, the possible recruitment of an inositol phosphate-sensitive calcium pool for myofibrillar activation, and the involvement of apoptotic myocyte and nonmyocyte cell death in myocardial remodeling.
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PMID:Molecular and cellular biology of heart failure. 883 64

Cardiomyopathies, and more specifically hypertrophic cardiomyopathy, have opened the route to what is now called genetic cardiology. Hypertrophic cardiomyopathy (HCM) is characterized by unexplained left and/or right ventricular hypertrophy, and disorganisation of tissular architecture. Approximately 60% of HCM are transmitted as an autosomal dominant trait. The clinical aspects of HCM vary markedly, and several morphological variants were described, depending on the localization of hypertrophy. This pathology is often complicated by cardiac failure, but the major risk is sudden death, and the predictive factors are presently very unrefined. Several pathogenic hypotheses were forwarded in the past, and one surprising result of genetic analyses is that none of these hypotheses was confirmed. Four disease genes were identified, and they encode sarcomeric proteins, cardiac myosin heavy chain, troponin T, tropomyosin and cardiac myosin binding protein C. To this high intergenic heterogeneity is associated a high intragenic heterogeneity. A major fall out of these genetic findings is the recent discovery of adult healthy carriers, around 30% in our experience. Genetype/phenotype relationships are being performed, and this is the first approach to a prognostic evaluation based on genetic localisation. The work on hypertrophic cardiomyopathy is currently being used as a model to analyse dilated cardiomyopathies, characterized by dilatation and impaired contraction of the left or both ventricles. The mode of inheritance of these forms of cardiomyopathies is complex. Five families with an autosomal inheritance were analyzed since two years, the loci were found, but the disease genes are not identified yet. Identification of patients at high risk and early treatment or prevention are the current goals.
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PMID:[Cardiomyopathies]. 929 66

Alterations in troponin T (TnT) isoforms have been reported in severe human and experimental heart failure (HF), and may play a role in the depressed myofibrillar ATPase activity observed in this condition. It is unclear whether these alterations reflect very severe hemodynamic derangement or are a component of mild hypertrophic stress. Therefore, we studied the expression of TnT isoforms (SDS-PAGE, Western blots), myosin isoforms, myofibrillar ATPase activity, and left ventricular (LV) mechanoenergetics (rbc perfused, isovolumically contracting isolated heart) in a rabbit model of mild hypertrophy (LVH) due to gradual hypertension caused by 12 weeks of cellophane wrap of the kidneys (n=12). LV/body weight ratio increased by 28% in LVH compared to shams (P<0.001); no animals had evidence of HF. In LVH, the percentage of TnT2 was modestly but significantly increased compared to shams [6.2+/-1.9 (+/-S.D. ) v 3.7+/-1.0%, P<0.05], mainly as a consequence of a parallel decrease in TnT4 (P=0.07). Sham hearts ranged from 75-100% V3 isomyosin, whereas all LVH hearts had 100% of the V3 form. There were no significant differences in myofibrillar ATPase activity or mechanical variables, including contraction and relaxation rates. The slope of the VO2-pressure-volume-area relation (a measure of the energy conversion efficiency of the contractile machinery) was also unchanged. We conclude that in the rabbit, shifts in TnT isoforms toward a more "fetal" pattern occur during mild LVH and, therefore, are likely to be a general feature of the response to hemodynamic stress, rather than a phenomenon confined to end-stage disease. These modest shifts are not associated with major alterations in LV myofibrillar ATPase activity or mechanoenergetics.
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PMID:Altered expression of troponin T isoforms in mild left ventricular hypertrophy in the rabbit. 929 58

We describe an improved procedure using a standard microplate immunoassay reader to measure the concentration of troponin T in human serum. We also describe an immunoassay for troponin I in serum. Only 160 microliters of serum are needed for a single analysis of each troponin. For comparison, creatine kinase MB mass analysis in serum was performed with a commercial luminometric method. From 95 apparently healthy people the following values were obtained: creatine kinase MB mass 2.6 +/- 1.2 micrograms/l, troponin T 0.027 +/- 0.025 microgram/l and troponin I 0.03 +/- 0.031 microgram/l. We compared the results of troponin T and troponin I methods with each other, as well as with those of creatine kinase MB mass measured in 48 patients with verified acute myocardial infarction and in 60 control patients with non-cardiac chest pain. The correlation between troponin T and troponin I values was 0.91 for the total material and 0.94 for 48 patients with acute myocardial infarction. Troponin I showed better earlier sensitivity than troponin T (p = 0.043). In nine patients in the control group, creatine kinase MB mass exceeded the reference limit of 5.0 micrograms/l, while in two patients the cut-off limit of 10.0 micrograms/l was also surpassed, pointing to non-specificity. In the group of infarct patients, the highest serum creatinine value was 193 mumol/l, whereas in the control group it was 406 mumol/l. The sera of patients with impaired renal function without any cardiac failure showed no increase in troponin T and troponin I values. In conclusion, serum creatine kinase MB mass and troponin I seem to confirm an acute myocardial infarction more rapidly than does troponin T; troponin I has the highest cardiac specificity.
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PMID:Comparison of the troponin T and troponin I ELISA tests, as measured by microplate immunoassay techniques, in diagnosing acute myocardial infarction. 936 95

Neonatal asphyxia is a major topic of neonatal research. However, no clear-cut physiologic parameters exist which enable an early identification of neonatal infants who are either at risk to develop brain damage or posthypoxic heart failure. Parameters indicating dysfunction of the heart and kidneys as creatinine and creatinine kinase have been evaluated. In our study, 47 asphyxiated infants (umbilical artery pH < 7.18 and either a 1-min Apgar score < 4 or a 5-min Apgar score < 7) were compared to 27 nonasphyxiated controls regarding significant differences in creatinine, creatinine kinase, its MB fraction, and a newly introduced myocardial hypoxia indicator -- troponin T -- to establish the value of these parameters in the retrospective diagnosis of asphyxia. Further we evaluated two subsets of these 47 asphyxiated infants with either subsequent signs of encephalopathy (seizures) or heart failure. Creatinine, creatinine kinase and troponin T were significantly elevated in asphyxiated infants compared with controls; no differences were found in creatinine kinase and its MB fraction. In asphyxiated infants with heart failure, troponin T was significantly higher than in the other asphyxiated infants. However, none of the parameters studied was significantly different in patients with brain damage compared with asphyxiated infants without neurological sequelae. Troponin T has a high positive predictive value in the postnatal diagnosis of asphyxia. The diagnostic power of troponin T equals that of creatinine. However, troponin T is more sensitive in the identification of infants with asphyxia and cardiocirculatory failure than creatinine. Creatinine kinase and its MB fraction have no diagnostic value.
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PMID:Value of myocardial hypoxia markers (creatine kinase and its MB-fraction, troponin-T, QT-intervals) and serum creatinine for the retrospective diagnosis of perinatal asphyxia. 961 54

The progression of cardiac failure is related to the loss of functional myocytes. The aim of these studies was to describe the structural degradation of the myocardium by the use of cardiac troponins as specific and sensitive markers of cardiac cell necrosis. The cardiac isoforms of troponin I and troponin T were measured in patients with NYHA class III-IV heart failure using second generation immunoassays without cross-reactivity with the skeletal isoforms of the two proteins. The results showed that the cardiac troponin I (72.1 +/- 15.8 vs 20.4 +/- 3.2 pg/mL; p < 0.01) and troponin T (0.21 +/- 0.6 vs 0.0005 +/- 0.002 ng/mL; p < 0.001) concentrations were significantly higher in patients with cardiac failure compared to a control population of healthy volunteers. These results suggest that troponin I and troponin T may have valuable clinical applications in the biological monitoring of cardiac failure and the appreciation of its progression.
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PMID:[The troponin complex: a new biochemical approach to cardiac insufficiency]. 989 19


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