Kiyoshi Doyama

Ventricular expression of brain natriuretic peptide in hypertrophic cardiomyopathy.

BackgroundBrain natriuretic peptide (BNP), as a cardiac hormone, is expressed together with atrial natriuretic peptide (ANP) in the ventricles in congestive heart failure. However, the ventricular expression of BNP in hypertrophic cardiomyopathy (HCM) with normal systolic function is still unclear. Methods and ResultsThe study population consisted of 39 HCM patients with asymmetric septal hypertrophy and 10 control subjects without any specific cardiac disease. Eleven cases of HCM were obstructive (HOCM), and the other 28 cases were nonobstructive (HNCM). All of these patients had a normal ejection fraction. Immunohistochemical analysis of endomyocardial biopsy specimens with specific monoclonal antibodies showed BNP immunoreactivity in the HOCM group (5/10, 50%) but not in the HNCM group (0/22) or in control subjects (0/5). In HOCM, left ventricular end-diastolic pressure was significantly higher in the BNP-positive patients than the BNP-negative patients. Histological changes such as myocardial fiber disarray, hypertrophy of myocytes, and fibrosis were greater in BNP-positive patients than BNP-negative patients in HCM. However, the expression had no significant relation with other clinical parameters. The elevation of the BNP plasma level versus control subjects was marked in both HOCM (85-fold) and HNCM (23-fold). By contrast, the elevation of the ANP plasma level versus control subjects was mild in HOCM (5.7-fold) and HNCM (4.2-fold). The ratio of BNP level to ANP level was higher in HOCM (4.16) than in HNCM (1.46) and control subjects (0.28), and it was higher than the ratio previously reported for severe congestive heart failure (1.72). ConclusionThese findings suggest that BNP is expressed in the ventricular myocytes of HCM with normal systolic function. In HOCM, ventricular expression of BNP may be augmented in response to both obstruction and diastolic dysfunction.

Expression of Atrial and Brain Natriuretic Peptides and Their Genes in Hearts of Patients With Cardiac Amyloidosis

OBJECTIVES We investigated the expression of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) and their genes in the hearts of patients with cardiac amyloidosis and those with isolated atrial amyloidosis. BACKGROUND The expression of ANP and BNP is augmented in the ventricles of failing or hypertrophied hearts, or both. The expression of ANP and BNP in the ventricles of hearts with cardiac amyloidosis, which is hemodynamically similar to restrictive cardiomyopathy, is not yet known. ANP is the precursor protein of isolated atrial amyloid. METHODS We analyzed the immunohistocytochemical localizations of ANP and BNP as well as the expression of their mRNAs by in situ hybridization in the myocardium and measured the plasma levels of ANP and BNP in patients with cardiac amyloidosis. RESULTS Four of the five right and all six left ventricular endomyocardial biopsy specimens obtained from six patients with cardiac amyloidosis were immunohistochemically positive for both ANP and BNP; none of the biopsy specimens from eight normal subjects were positive for ANP or BNP. All four of the right atria obtained at operation showed positive immunoreactions for both peptides. Electron microscopy identified specific secretory granules in ventricular myocytes of the patients with cardiac amyloidosis, but not in ventricular myocytes from the normal control subjects. Double immunocytochemical analysis revealed the co-localization of ANP and BNP in the same granules and that isolated atrial amyloid fibrils were immunoreactive for ANP and BNP, whereas ventricular amyloid fibrils were negative for both peptides. Both ANP mRNA and BNP mRNA were expressed in the ventricles of the patients with cardiac amyloidosis but not in the normal ventricles. The autopsy study of four patients with cardiac amyloidosis revealed an almost transmural distribution of ANP and BNP, with predominance in the endocardial side. Plasma BNP levels in the patients were markedly elevated ([mean +/- SD] 1,165.1+/-561.2 pg/ml) compared with those in the control subjects (8.9+/-6.0 pg/ml, p < 0.05). CONCLUSIONS Expression of ANP and BNP and their genes was augmented in the ventricular myocytes of the patients with cardiac amyloidosis. Both regional mechanical stress by amyloid deposits and hemodynamic stress by diastolic dysfunction may be responsible for the expression of the peptides in patients with cardiac amyloidosis.

Expression and distribution of brain natriuretic peptide in human right atria

OBJECTIVES We investigated expression of brain natriuretic peptide (BNP) as well as atrial natriuretic peptide (ANP) and their genes in human right atria. Their relations with atrial pressure were also examined. BACKGROUND The BNP plays a roll in electrolyte-fluid homeostasis such as ANP. The tissue level is reported to be elevated in the failing ventricles. However, expression and transmural distribution of BNP in the atria remain unclear. METHODS Expression of ANP and BNP was immunohistochemically investigated in the right atrial (RA) specimens from 21 patients who had undergone cardiac surgery. The mRNA of specimens were quantitatively measured by Northern blot analysis and also evaluated by in situ hybridization. In addition, plasma levels of ANP and BNP were measured in the patients. RESULTS The BNP immunoreactivity was diffusely seen in RA tissue of patients with mean RA pressure (mRAP) of 5 mm Hg or more, but it was noted only in the subendocardial half of the atria of those with mRAP less than 5 mm Hg. There was a significant correlation between the incidence of BNP-positive myocytes and mRAP (r = 0.850, p < 0.0001). Conversely, ANP-positive myocytes were found diffusely in all cases. In Northern blot analysis, the mRNAs levels of ANP and BNP in the atrial tissue were positively correlated with the mRAP (ANP, p = 0.775, p < 0.005 and BNP, p = 0.771, p < 0.005). In situ hybridization confirmed these findings. The mRNA levels were significantly correlated to each other (r = 0.845, p < 0.0002). Plasma ANP and BNP levels were elevated in the patients compared with that in controls; however, none were significantly correlated with the mRAP. CONCLUSIONS Expression of BNP and BNP mRNA is augmented in the atria with increased pressure, and distributed predominantly in the subendocardial side. The level of BNP mRNA was well correlated with that of ANP mRNA. Thus, these two genes might be commonly regulated in response to atrial pressure.

Endothelin-1 and Its Receptor in Hypertrophic Cardiomyopathy

Endothelin-1, a potent vasoconstrictor produced by vascular endothelial cells, activates the hypertrophic program in cultured heart muscle cells. However, the role of endothelin-1 in cardiac hypertrophy in humans is unknown. Therefore, we studied hypertrophic cardiomyopathy patients with normal pulmonary arterial pressure, in whom cardiac hypertrophy is a specific feature of the disease. Radioimmunoassay with a monoclonal antibody to human endothelin-1 showed that the plasma level of immunoreactive endothelin was more than twofold higher in hypertrophic cardiomyopathy patients than in control subjects (P < .005). In situ hybridization analysis of endomyocardial biopsy specimens showed positive signals of endothelin-1 type A receptor mRNA in ventricular myocytes of all specimens. The receptor expression in ventricular myocytes was similar between hypertrophic cardiomyopathy patients and control subjects. We propose that endothelin-1 might represent an important factor involved in hypertrophic cardiomyopathy. Whether endothelin-1 plays a causal role in cardiac hypertrophy or is a marker of its occurrence needs to be clarified.

Tumour necrosis factor is expressed in cardiac tissues of patients with heart failure

Tumour necrosis factor (TNF), a cytokine produced mainly by macrophages, has also been found in vascular smooth muscle cells. Elevated serum levels of TNF have been reported in various cardiac diseases, especially congestive heart failure (CHF). Although the myocardium produces several cytokines, the expression of TNF in human cardiac tissue has not yet been demonstrated. We examined TNF expression in right atrial (RA) specimens obtained from 15 patients during cardiac surgery with immunohistochemistry using an anti-human TNF monoclonal antibody, enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase polymerase chain reaction (RT-PCR). TNF immunoreactivity was found only in cardiac myocytes and some vascular smooth muscle cells of small vessels of specimens from patients with severe CHF (3/5), and not in those from patients without severe CHF (0/10). ELISA of four RA specimens revealed that RA tissues from two patients with severe CHF contained more TNF than did those from two patients without severe CHF (3.1 and 4.7 pg/mg vs. 0.1 and 0.3 pg/mg). RT-PCR revealed TNF mRNA in all seven cases we examined. It was concluded that TNF mRNA is expressed by atrial tissue. The production of immunoreactive TNF-like peptides by myocytes and vascular smooth muscle cells is augmented in patients with severe CHF.

Endothelin-1-selective receptor in the arterial intima of patients with hypertension

Endothelin-1 is a potent vasoconstrictor produced by vascular endothelial cells. A recently cloned endothelin-1-selective receptor, the endothelin-A receptor, mediates the vasoconstrictive action of endothelin-1. Because endothelin-1 also possesses mitogenic properties, it may play a role in regulating the proliferation of intimal smooth muscle cells. In this study, we analyzed the expression of endothelin-A receptor gene in the thickened arterial intima of patients with hypertension. Internal mammary artery specimens obtained from 12 patients undergoing cardiovascular surgery were subjected to in situ hybridization using a digoxigenin-labeled cRNA probe. High, homogeneous signals of endothelin-A receptor mRNA were observed in the medial smooth muscle cells of all vessels examined but not in the endothelial cells. Patients with hypertension displayed more severe intimal thickening than those without hypertension. Immunohistochemical analysis suggested that almost all of the intimal proliferative cells originated from smooth muscle cells. In contrast to media, endothelin-A receptor mRNA signals in intimal smooth muscle cells were low and heterogeneous. In the thickened arterial intima of hypertensive patients, the signals were detected just beneath the luminal endothelium but not deep in the intimal smooth muscle cell layer. By contrast, staining with anti-alpha-smooth muscle actin antibody was more intense in the deep layer than in the subendothelium. These findings suggest that the modulation of endothelin-A receptor gene expression in smooth muscle cells differs between the intima and media. Its regulated expression in intimal smooth muscle cells might affect the proliferative activity of these cells in patients with hypertension.

Immunomodulation: A new horizon for medicaltreatment of heart failure

Recently, the intriguing possibility has been raised that heart failure may be mediated by the biological effects of cytokines. Indeed, we found elevation of plasma concentrations of various cytokines in patients with myocardial disease. We also detected positive tumor necrosis factor (TNF-alpha) immunoreactivity in right atrial tissues obtained during surgery from patients with severe heart failure. Therefore, we postulated that some aspects of heart failure may be related to non-lethal down-modulation of cardiac function by immune cells and their cytokines. Testing this hypothesis in an experimental model of murine myocarditis, we found that injection of recombinant human TNF-alpha increased mortality of the animals infected with myocarditis virus. The anti-TNF-alpha monoclonal antibody improved survival and attenuated the myocardial lesions. Whereas, administration of recombinant human IL-2 in the acute viremic stage increased survival rate, and resulted in less intense pathological changes in the myocardium while in the subacute aviremic stage, the same amount of IL-2 reduced survival rate and exacerbated severity of the disease. Therefore, cytokine release may initiate a beneficial inflammatory and immune response in the acute phase of the disease process, but the continued induction of cytokines and the enhanced natural killer (NK) cell activity in the later stage are no longer protective. Vesnarinone, a recently synthesized inotropic agent which has proved to benefit patients with congestive heart failure by improving prognosis, also increased the survival of individual subjects in the above-mentioned murine model of heart failure. Cytotoxicity of NK cells obtained from the virus infected animals was substantially reduced when treated with vesnarinone. Vesnarinone also inhibited production of TNF-alpha and other cytokines from stimulated human lymphocytes and cultured murine splenocytes. We conclude, therefore, that inhibition of NK cell activity and suppression of cytokine production appear to be important immunological defense mechanisms which could contribute to the observed salutary effects of vesnarinone in the treatment of chronic heart failure. More broadly, immunomodulation could pave the way for a new frontier in the management of heart failure.

Management of Multiple Cholesterol Embolization Syndrome-A Case Report

A sixty-two-year-old man who underwent coronary angiography and received acute thrombolytic and anticoagulant therapy for acute myocardial infarction developed multisystemic injury, including renal insufficiency and cutaneous manifestations. Fundoscopic examination and skin biopsy specimen led to the diagnosis of multiple cholesterol embolization syndrome (MCES). Discontinuation of anticoagulants and administration of hemostatic (carbazochrome, tranexamic acid, reptilase, and vitamin K) and antihyperlipidemic (cholestyramine and probucol) drugs resulted in temporary improvement of cutaneous and renal disorders and extended survival for about one year. Besides severe aortic atherosclerosis, postmortem examination revealed numerous cholesterol emboli to multiple organs. MCES is a rare but serious complication of left heart catheterization and anticoagulant therapy, and the optimal treatment remains to be established. The authors suggest here that the above-mentioned therapy might be effective for management of MCES.

Up-regulated expression of angiotensin II type 1 receptor gene in human pathologic hearts

BACKGROUND An accumulation of evidence suggests that the local renin-angiotensin system plays a role in the development of cardiac hypertrophy in vivo; however, it remains unknown how the expression of angiotensin II type 1 receptor (AT1), which mediates most of the cardiovascular effects of angiotensin II, is regulated in the left ventricles of human pathologic hearts. METHODS AND RESULTS Expression of AT1 gene in the left ventricle wall of 14 autopsied human hearts was examined by reverse transcription polymerase chain reaction. The levels of AT1 messenger RNA relative to those of beta-actin messenger RNA in the left ventricle wall were increased 3.8-fold in the hearts with dilated cardiomyopathy (n = 4, P < .05) and 6.2-fold in the noninfarcted areas of hearts with old myocardial infarction (n = 4, P < .05), compared with the control hearts without any cardiac disease (n = 6). The increases in the relative AT1 messenger RNA level showed a positive correlation with myocyte diameter in the adjacent tissue (r = .927, P < .001 for dilated cardiomyopathy and r = .934, P < .005 for old myocardial infarctions) and with the extent of fibrosis (r = .880, P < .005 for dilated cardiomyopathy and r = .690, P < .05 for old myocardial infarction). CONCLUSIONS Expression of AT1 in these human pathologic hearts was associated with myocardial cell hypertrophy and extent of fibrosis, a finding that further emphasizes the importance of the local renin-angiotensin system in the remodeling of human hearts with dilated cardiomyopathy and old myocardial infarction.

Kawasaki disease complicated by acute myocardial infarction 9 years after onset

17. Lindberg HA, Berkson DM, Stamler J, Poindexter A: Totally asymptomatic myocardial infarction: An estimate of its incidence in the living population. Arch Intern Med 5:628, 1960. Melichar F, Jedlicka V, Havlik L: A study of undiagnosed myocardial infarctions. Acta Med Stand 174:761, 1963. Margolis JR, Kannel WB, Feinleib M, Dawber TR, McNamara PM Clinical features of unrecognized myocardial infarction-silent and symptomatic. Eighteen year follow-up: The F ,ammgham study. Am J Cardiol 32:1, 1973. Rosen1 ran RH, Friedman M, Jenkins CD, Straus R, Wurm M, Kositchek R: Clinically unrecognized myocardial infarction in the Western collaborative group study. Am J Cardiol 19:776, 1967. Kannel WB, Abbott RD: Incidence and prognosis of unrecognized myocardial infarction: An update on the Framingham study. N Engl J Med 311:1144, 1984.