| 1. |
- Bollano, Entela, 1970, et al.
(författare)
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Different responses to dobutamine in the presence of carvedilol or metoprolol in patients with chronic heart failure.
- 2003
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Ingår i: Heart (British Cardiac Society). - 1468-201X. ; 89:6, s. 621-4
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Tidskriftsartikel (refereegranskat)abstract
- To determine whether patients with congestive heart failure on different beta adrenoreceptor blocking drugs have similar haemodynamic responses to dobutamine.Single centre, single blind, randomised, two period crossover study comparing carvedilol with metoprolol CR/XL.Ten patients with stable chronic congestive heart failure (ejection fraction < 40%) on chronic treatment with metoprolol CR/XL.Patients were treated with carvedilol or metoprolol CR/XL (target dose 50 mg twice daily and 200 mg once daily, respectively) for eight weeks. Stress echocardiography was undertaken at the end of each maintenance period, using dobutamine 5 and 15 microg/kg/min.No significant haemodynamic differences were seen at rest on the two treatments. There was a more pronounced increase in heart rate and cardiac output during dobutamine infusion when the patients were on metoprolol than when they were on carvedilol. Mean arterial pressure increased significantly when the patients were on carvedilol, and cardiac output increased during low dose dobutamine, without further change during high dose dobutamine. During the dobutamine infusion, there was no significant difference in ejection fraction between carvedilol and metoprolol treatment.Patients with congestive heart failure on a non-selective beta adrenoreceptor blocker or beta1 selective blocker responded differently to the inotropic drug dobutamine: the beta1 blockade caused by metoprolol could be counteracted by dobutamine, whereas with carvedilol a low dose of dobutamine increased cardiac output, and a higher dose of dobutamine caused a pressor effect. These findings may be clinically relevant when choosing an inotropic drug.
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| 2. |
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| 3. |
- Fu, Michael, 1963, et al.
(författare)
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Autoantibodies against the angiotensin receptor (AT1) in patients with hypertension.
- 2000
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Ingår i: Journal of hypertension. - 0263-6352. ; 18:7, s. 945-53
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Tidskriftsartikel (refereegranskat)abstract
- Sera from patients with malignant essential hypertension (n = 14), malignant secondary hypertension mainly attributable to renovascular diseases (n = 12) and renovascular diseases without malignant hypertension (n = 11) and from normotensive healthy blood donors (n = 35) were studied for the presence of autoantibodies against G-protein-coupled cardiovascular receptors. Autoantibodies against the angiotensin II receptor (AT1) were detected in 14, 33, 18 and 14% of patients with malignant essential hypertension, malignant secondary hypertension, renovascular diseases and control patients, respectively. Sensitivity of the enzyme immunoassay was assessed as 5 microg/ml IgG. Patients did not show antibodies against bradykinin (B2) or angiotensin II subtype 2 (AT2) receptors. Autoantibodies affinity-purified from positive patients localized AT receptors in Chinese hamster ovary transfected cells, and displayed a positive chronotropic effect on cultured neonatal rat cardiomyocytes. These results demonstrate the existence of autoantibodies against a functional extracellular domain of human AT1 receptors in patients with malignant hypertension, and suggest that these autoantibodies might be involved in the pathogenesis of malignant hypertension.
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| 4. |
- Fu, Michael, 1963, et al.
(författare)
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Myocardial hypertrophy in transgenic mice overexpressing the bovine growth hormone (bGH) gene.
- 2000
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Ingår i: Journal of internal medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 247:5, s. 546-52
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: The main purpose of the present study was to characterize cardiac muscle hypertrophy using both qualitative and quantitative microscopy in mice overexpressing the bovine growth hormone. RESULTS: Measurements of 30 fibres from each group revealed that fibre diameter in transgenic hearts was significantly larger than in control hearts. There was a significant decrease in interfibrillar space in transgenic hearts as compared with control hearts. The enlarged transgenic hearts displayed unchanged organelles such as normal myofibrils and mitochondria in a normal pattern, suggesting balanced growth. Myelin structures were occasionally observed between normal myofibrils. Moreover, myocardial beta-adrenergic receptors and muscarinic receptors in the hearts of transgenic mice overproducing GH were studied to see whether they are involved in the hypertrophic process. It was shown that the density of muscarinic receptors had decreased and the super-high affinity of muscarinic receptors was lost, without any significant changes in either the density or the affinity of beta-adrenergic receptors, as compared with controls. CONCLUSIONS: These results demonstrate that a GH excess was able to induce significant myocardial hypertrophy and that there was a downregulation of muscarinic receptors.
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| 5. |
- Levin, Malin, 1973, et al.
(författare)
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A novel polymorphism in the gene coding for the beta(1)-adrenergic receptor associated with survival in patients with heart failure.
- 2000
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Ingår i: European heart journal. - : Oxford University Press (OUP). - 0195-668X. ; 21:22, s. 1853-8
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: The adrenergic nervous system is of major importance in congestive heart failure. No genetic polymorphism has previously been identified in the beta(1)-adrenergic receptor gene. The aim of this study was to find possible mutations in this gene and to relate such findings to morbidity and prognosis in heart failure. METHODS AND RESULTS: Genomic DNA was extracted from blood leukocytes from patients with congestive heart failure (n=184) and from age-matched controls (n=77). The part of the beta(1)-adrenergic receptor gene corresponding to nucleotide 1-255 was amplified by polymerase chain reaction and analysed by automated sequencing. The patients were investigated by echocardiography and followed regarding symptoms and survival for 5 years. A missense mutation was identified at nucleotide position 145 in the beta(1)-adrenergic receptor gene, which predicted an amino acid substitution at position 49 (Ser49Gly). The allele frequency of the Gly49 variant was 0.13 in controls and 0.18 in patients (P=0.19). At the time of the 5-years follow-up, 62% of the patients with the wild type gene and 39% of the patients with the Ser49Gly variant had died or had experienced hospitalization (P=0.005). Patients without the mutation had significantly poorer survival compared to those with the mutation, risk ratio 2.34 (95% CI 1.30-4.20), P=0.003. In a mulivariate analysis, the risk ratio was 2.03 (95% CI 0.99-4.16) P=0.05. CONCLUSION: A novel missense mution in the beta(1)-adrenergic receptor gene was associated with a decreased mortality risk in patients with congestive heart failure. These data suggest that the beta(1)-receptor Ser49Gly variant might be associated with altered receptor function, resulting in myocardial protection in patients with heart failure.
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| 6. |
- Mobini, Reza, 1965, et al.
(författare)
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A monoclonal antibody directed against an autoimmune epitope on the human beta1-adrenergic receptor recognized in idiopathic dilated cardiomyopathy.
- 2000
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Ingår i: Hybridoma. - : Mary Ann Liebert Inc. - 0272-457X. ; 19:2, s. 135-42
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Tidskriftsartikel (refereegranskat)abstract
- A monoclonal antibody (MAb M16) was obtained by immunizing Balb/C mice with free peptide H26R, corresponding to the second extracellular loop of the human beta1-adrenergic receptor (beta1AR), against which functional autoantibodies have been detected in patients with idiopathic dilated cardiomyopathy. The MAb was found to be of IgG2b type and directed against a conformational epitope, encompassing the sequence recognized by the human autoantibodies. BIAcore measurements yielded an equilibrium constant of 6.5 X 10(7) M1 with an association rate constant (kon) of 6.5 X 10(4) M(-1) sec(-1) and a dissociation rate constant (koff) of 1.0 X 10(-3) sec(-1). It immunoprecipitated only poorly the solubilized beta1AR of Sf9 cell membranes. Functionally, the MAb was capable of not only reducing the number of the maximal binding sites to the beta1-adrenergic receptor of transfected Sf9 cell membranes, but also of displaying a positive chronotropic effect on cultured neonatal rat cardiomyocytes. These properties, which the MAb shares with the human autoantibodies, makes it an interesting tool for passive transfer studies in mice.
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| 7. |
- Mobini, Reza, 1965, et al.
(författare)
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Hemodynamic improvement and removal of autoantibodies against beta1-adrenergic receptor by immunoadsorption therapy in dilated cardiomyopathy.
- 2003
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Ingår i: Journal of autoimmunity. - 0896-8411. ; 20:4, s. 345-50
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Tidskriftsartikel (refereegranskat)abstract
- The removal of beta(1)-adrenergic receptor (beta(1)AR) autoantibodies by immunoadsorption (IA) has been proposed as a potential mechanism for the improvement of the left ventricular function in dilated cardiomyopathy (DCM). In the present study, the possible association between removal of the autoantibodies against the human beta(1)AR with the hemodynamic improvement induced by IA was investigated.IA was performed in 22 DCM patients (n=22; NYHA III-IV, EF<30%, stable medication). The beta(1)AR autoantibodies from column eluents (CE) were detected by enzyme-linked immunosorbent assay (ELISA) and BIAcore methods. CE of 32% (7/22) of the patients was found to be antibody-positive with ELISA or BIAcore. In addition, a bioassay system was also used for the detection of this autoantibody. Seventy-three percent (16/22) of the patients were found to be antibody-positive by this method. However, independent of the beta(1)AR antibody detection method, both antibody-positive and antibody-negative groups showed similar acute and prolonged hemodynamic improvements during IA therapy. Furthermore, antibody-positive and -negative groups received a comparable improvement of left ventricular ejection fraction.These results suggest that different mechanisms are involved in the hemodynamic improvement induced by IA. The beneficial hemodynamic effects induced by IA are not directly associated with the removal of beta(1)AR autoantibodies.
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| 8. |
- Omerovic, Elmir, 1968, et al.
(författare)
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Growth hormone improves bioenergetics and decreases catecholamines in postinfarct rat hearts.
- 2000
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Ingår i: Endocrinology. - 0013-7227. ; 141:12, s. 4592-9
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Tidskriftsartikel (refereegranskat)abstract
- The aims of this study were to examine, in vivo, the effects of GH treatment on myocardial energy metabolism, function, morphology, and neurohormonal status in rats during the early postinfarct remodeling phase. Myocardial infarction (MI) was induced in male Sprague Dawley rats. Three different groups were studied: MI rats treated with saline (n = 7), MI rats treated with GH (MI + GH; n = 11; 3 mg/kg x day), and sham-operated rats (sham; n = 8). All rats were investigated with 31P magnetic resonance spectroscopy and echocardiography at 3 days after MI and 3 weeks later. After 3 weeks treatment with GH, the phosphocreatine/ATP ratio increased significantly, compared with the control group (MI = 1.69 +/- 0.09 vs. MI + GH = 2.42 +/- 0.05, P < 0.001; sham = 2.34 +/- 0.08). Treatment with GH significantly attenuated an increase in left ventricular end systolic volume and end diastolic volume. A decrease in ejection fraction was prevented in GH-treated rats (P < 0.05 vs. MI). Myocardial and plasma noradrenaline levels were significantly lower in MI rats treated with GH. These effects were accompanied by normalization of plasma brain natriuretic peptide levels (sham = 124.1 +/- 8.4; MI = 203.9 +/- 34.7; MI + GH = 118.3 +/- 8.4 ng/ml; P < 0.05 vs. MI). In conclusion, GH improves myocardial energy reserve, preserves left ventricular function, and attenuates pathologic postinfarct remodeling in the absence of induction of left ventricular hypertrophy in postinfarct rats. The marked decrease in myocardial content of noradrenaline, after GH treatment, may protect myocardium from adverse effects of catecholamines during postinfarct remodeling.
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| 9. |
- Omerovic, Elmir, 1968, et al.
(författare)
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Induction of cardiomyopathy in severe combined immunodeficiency mice by transfer of lymphocytes from patients with idiopathic dilated cardiomyopathy.
- 2000
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Ingår i: Autoimmunity. - 0891-6934. ; 32:4, s. 271-80
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Tidskriftsartikel (refereegranskat)abstract
- Growing evidence suggests that autoimmune mechanisms play an important role in the pathogenesis of idiopathic dilated cardiomyopathy (DCM). The aim of the study was to evaluate the effects of transfer of lymphocytes from patients with DCM into severe combined immunodeficiency (SCID) mice on the heart structure and function. Thirty CB-17 SCID (6-8 weeks old) mice were used and divided into 3 groups (n = 10). Mice were injected intraperitoneally with up to 25 x 10(6) peripheral blood lymphocytes (PBL) from either patients with DCM which contain human autoantibodies against cardiac beta1-adrenergic receptors and M2-muscarinic receptors (DCM group) or PBL from healthy controls (control-H group). Ten mice did not receive any injections and were used as baseline controls (control-N group). Echocardiography and morphological studies were performed seventy five days after the transfer. Results showed that in DCM group, left ventricle dimensions (LVD) in diastole were increased (4.2 +/- 0.1mm) as compared to both control-H group (3.8 +/- 0.1mm) and control-N group (3.6 +/- 0.1 mm) (p < 0.01). Further, there was a trend for increased LVD in systole. Fractional shortening was not different between groups. Histological evaluation revealed accumulation of human lymphocytes in the capillaries and scarce infiltration of the lymphocytes in the hearts from DCM group. Diffuse fibrosis was significant increased in DCM mice as compared to mice receiving PBL from normal subjects (2.2 +/- 0.3% vs. 0.8 +/- 0.1%, p < 0.01). In conclusion, transfer of the PBL from the patients with DCM was able to induce early stage of heart dilatation in SCID mice. These data provide for the first time the direct evidence supporting that the autoimmune mechanism is important in the pathogenesis of human DCM.
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| 10. |
- Wang, W, et al.
(författare)
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Stimulatory activity of anti-peptide antibodies against the second extracellular loop of human M2 muscarinic receptors.
- 2000
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Ingår i: Chinese medical journal. - 0366-6999. ; 113:10, s. 867-71
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To study the activity of anti-peptide antibodies against the second extracellular loop of human M2 muscarinic receptors on cAMP production and inward calcium currents (Ica) in guinea pig ventricular myocytes. A comparison was also made with those of a muscarinic receptor agonist. METHODS: cAMP content was determined by radioimmunoassay and the Ica in guinea pig single ventricular cells were recorded by the whole-cell patch clamp technique. RESULTS: Both the muscarinic receptor agonist, carbachol (Carb 10 mumol/L), and anti-peptide antibodies (Abs 100 nmol/L) could decrease basal cAMP levels (by 46.9% +/- 4.2% and 60.2% +/- 4.6%, respectively) and basal Ica. Both Carb (10 mumol/L) and Abs (100 nmol/L) could also inhibit the isoprenaline-induced (Iso 0.8 mumol/L) increases in cAMP production (from 108.2 +/- 7.0 to 88.4 +/- 7.2 pmol/mg.protein/min for Carb and 88.6 +/- 5.1 pmol/mg.protein/min for Abs, respectively) and the increases in Ica. The muscarinic receptor antagonist atropine (Atr) was able to prevent these effects of Carb and Abs. CONCLUSIONS: Anti-peptide antibodies against an epitope located in the second extracellular loop of human M2 muscarinic receptors, similar to muscarinic receptor agonist, could decrease the basal Ica and beta-receptor agonist stimulated increase of Ica by decreasing the basal and beta-receptor agonist stimulated increase of cAMP production, and therefore could have an effect on their target receptor. These results further suggest that autoimmunity may participate in the pathogenesis of human cardiomyopathy and the second extracellular loop of human M2 muscarinic receptor could be the main immunodominant region.
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