Manabu Setoguchi

Dystrophin-deficient myocardium is vulnerable to pressure overload in vivo

OBJECTIVE Dystrophin provides mechanical reinforcement to the membranes of myocytes. Dystrophin abnormalities are known to cause cardiomyopathy and skeletal muscle disorders; however, the pathogenesis of these abnormalities remains unclear. Dystrophin-deficient skeletal muscle is vulnerable to stresses such as stretch and hypo-osmotic shock. We investigated whether the myocardium of dystrophin-deficient (mdx) mice shows increased vulnerability to acute pressure overload in vivo. METHODS AND RESULTS Abdominal aortic banding was performed in 12-week-old mdx and control mice. The aortic pressure was measured by cannulation of the right carotid artery at the time of sacrifice. Systolic pressures in mdx mice at 0, 1, 2, 7 and 14 days after aortic banding were 100 +/- 11, 119 +/- 7, 123 +/- 4, 134 +/- 11 and 130 +/- 10 mmHg, respectively. Microscopic analysis revealed focal lesions in the left ventricular wall in banded mdx mice. These lesions consisted of damaged myocytes and inflammatory cells, and also of fibrosis at a late stage. Similar lesions were not observed in non-banded or banded control mice. The proportion of areas of lesions to total left ventricular area increased over time: 1.0 +/- 0.6% in mdx mice without aortic banding (sham, n = 6), and 1.7+/-1.4% 1 day (n = 6, vs. sham, NS), 2.6 +/- 1.9% 2 days (n = 7, vs. sham, P < 0.05), 6.3+ /- 6.5% 7 days (n = 13, vs. sham, P < 0.05) and 9.9 +/- 8.3% 14 days after aortic banding (n=15, vs. sham, P < 0.01). Furthermore, linear regression analysis revealed a significant correlation between percentage of lesion area and systolic pressure in mdx mice (P < 0.05). CONCLUSION Dystrophin-deficient myocardium is more vulnerable than normal myocardium to pressure overload in vivo. This result has two clinical implications: (1) the patients with dystrophynopathy, such as the Duchenne and the Becker types of muscular dystrophy and X-linked type of dilated cardiomyopathy, who develop arterial hypertension should be treated aggressively, and (2) they should avoid stresses that elevate blood pressure.

Statins suppress interleukin-6-induced monocyte chemo-attractant protein-1 by inhibiting Janus kinase/signal transducers and activators of transcription pathways in human vascular endothelial cells

Background and purpose:  The mechanisms of anti‐inflammatory actions of statins, 3‐hydroxy‐3‐methylglutaryl CoA (HMG‐CoA) reductase inhibitors, remain unclear. We investigated the effects of statins on interleukin (IL)‐6‐induced monocyte chemo‐attractant protein (MCP)‐1 expression and monocyte chemotaxis.

Cardiac dystrophin abnormalities in Becker muscular dystrophy assessed by endomyocardial biopsy

Duchenne and Becker muscular dystrophy (DMD/BMD) are allelic variants caused by mutations in gene-encoding dystrophin. Abnormal expression of dystrophin in skeletal muscle has been shown to correlate with severity of disease. However, in BMD the severity of skeletal and cardiac involvement are not well correlated. We studied the immunostaining pattern of cardiac dystrophin in endomyocardial biopsy specimens from 83 patients with heart disease. Immunohistochemical assessment of dystrophin in four patients with BMD and cardiomyopathy showed a variable distributions of myocytes with continuous, discontinuous, or absent membrane immunostaining patterns. These patterns were obviously different from patterns of other heart diseases. We conclude that the discontinuous immunostaining pattern of cardiac dystrophin is characteristic of BMD and that an absent pattern may be associated with more severe cardiac dysfunction. Because genetic analysis cannot determine the correct diagnosis in 35% of DMD/BMD cases, we recommend routine examination of immunostaining patterns of dystrophin in endomyocardial biopsy specimens in patients with cardiomyopathy suspected to be the result of BMD.

Immunofluorescence analysis of trihexosylceramide accumulated in the hearts of variant hemizygotes and heterozygotes with Fabry disease

An immunofluorescence method was applied to detect trihexosylceramide accumulated in the cardiac tissues from a variant hemizygote and a heterozygous female with Fabry disease, the incidence of which had been suspected to be high.

Cardiac tamponade due to rupture of coronary artery fistula to the coronary sinus with giant aneurysm of coronary artery: usefulness of transthoracic echocardiography

A 68-year-old woman was admitted to our hospital because of back pain and syncope. Transthoracic echocardiography revealed pericardial effusion, a collapsed right ventricle, a giant aneurysm connected to the coronary sinus, a dilated left main trunk coronary artery, and a dilated left circumflex artery (LCx). Furthermore, there was a coronary artery fistula arising from the LCx that drained into the coronary sinus. We diagnosed cardiac tamponade due to rupture of the coronary artery fistula or giant aneurysm, and successful emergency surgery was performed. Rupture of coronary artery aneurysm or coronary artery fistula is very rare. Transthoracic two-dimensional echocardiography was very useful in our case for the diagnosis of cardiac tamponade, giant coronary aneurysm, and coronary artery fistula.

Relationship between vascular endothelial growth factor and left ventricular dimension in patients with acute myocardial infarction.

BACKGROUND Although vascular endothelial growth factor (VEGF) is elevated in patients with acute myocardial infarction (AMI), the clinical significance of its elevation remains unclear. The present study was designed to determine the relationship between VEGF and left ventricular dimension in patients with AMI. METHODS AND RESULTS Plasma VEGF levels were examined by enzyme-linked immunosorbent assay daily for one week and then weekly for four weeks in 38 patients with AMI (65.4 ± 1.7 years). Left ventriculography was performed at 14 days, 6 months, and 2 years after the onset of AMI. Plasma VEGF levels were significantly elevated and reached a peak on day 6. Peak plasma VEGF levels positively correlated with both end-diastolic and end-systolic volume indices at 14 days after the onset of AMI. When patients with AMI were divided into two groups according to plasma VEGF levels on admission, left ventricular volume indices were higher in the high VEGF group than in the low VEGF group at the subacute phase of AMI (14 days). These differences were no longer present in the chronic phase of AMI. CONCLUSION Plasma VEGF levels were increased in patients with AMI, and peak levels were associated with left ventricular volume indices in the subacute phase, suggesting an important role of endogenous VEGF in the left ventricular dimension in patients with AMI.