Muneaki Matsubara

Single dose GLP-1-Tf ameliorates myocardial ischemia/reperfusion injury.

BACKGROUND Glucagon-like peptide-1 (GLP-1) has insulinomimetic, insulinotropic, and antiapoptotic properties that may make it a useful adjunct to reperfusion therapy for myocardial infarction (MI); however, GLP-1 has a short plasma half-life. Fusion of GLP-1 to human transferrin (GLP-1-Tf) significantly prolongs drug half-life. MATERIALS AND METHODS We tested the ability of single dose GLP-1-Tf to limit myocardial ischemia (30 min)/reperfusion (180 min) injury in rabbits. Nineteen animals were untreated controls. The pre-ischemic group (n=10) was given 10mg/kg of GLP-1-Tf 12 h before ischemia. Immediately after reperfusion, the post-ischemic group (n=10) received GLP-1-Tf (10 mg/kg) and the Tf group (n=4) received transferrin alone. RESULTS Infarct size as a percentage of the area at risk was 59.1% ± 1.3%, 45.7% ± 1.9%, 44.1% ± 3.3%, 59.7% ± 2.0% in the control group, pre-ischemic group, post-ischemic group, and Tf group, respectively (P<0.05 for both GLP-1-Tf treatments group versus control). GLP-1-Tf reduced the apoptotic index from 4.67% ± 0.40% in the control group to 3.15% ± 0.46% in the pre-ischemic group and to 2.66% ± 0.40% in the post-ischemic group (P<0.05 for both GLP-1-Tf treatments versus control). The size of the wall motion abnormality and ejection fraction was significantly improved in the post-ischemic group relative to the control group. Serum GLP-1 levels were 239.8 ± 25.7 μg/mL in the post-ischemic group, 27.9 ± 5.8 μg/mL in the pre-ischemic group, and undetectable in the control group. CONCLUSION GLP-1-Tf limits myocardial reperfusion injury whether given prior to the onset of ischemia or given at reperfusion. GLP-1-Tf may also limit myocardial stunning at high serum levels of the drug.

Mild Hypothermia to Limit Myocardial Ischemia-Reperfusion Injury: Importance of Timing

BACKGROUND Hypothermia during ischemia has been shown to reduce myocardial reperfusion injury. We sought to establish the cardioprotective effect of very mild total-body hypothermia (<or= 2.5 degrees C) and to determine whether the application of hypothermia at different points during the ischemia-reperfusion period influenced the degree of myocardial salvage. METHODS Rabbits were subjected to 30 minutes of myocardial ischemia followed by 3 hours of reperfusion. Twenty-five animals were maintained at normal temperature (39.5 degrees C) throughout the experiment (W-W-W group). All other animals were cooled to reduce left atrial temperature 2.0 degrees C to 2.5 degrees C. Eleven animals reached goal temperature before coronary occlusion (C-C-C group), in 14 animals cooling was initiated at coronary occlusion (W-C0-C group), in 8 animals cooling was initiated 15 minutes after coronary occlusion (W-C15-C group), in 5 animals cooling was initiated 25 minutes after coronary occlusion (W-C25-C group), and in 13 animals cooling was started concurrently with reperfusion (W-W-C group). Infarct size as a percentage of the risk area (I/AR) was determined by a double staining-planimetry technique. RESULTS Goal temperature was achieved before reperfusion in the C-C-C and W-C0-C groups but was not achieved until the reperfusion period in the other treatment groups. Infarct size was 59.0 +/- 1.2% in the W-W-W group and was reduced in all cooling groups (C-C-C = 30.4 +/- 4.9%; W-C0-C = 33.4 +/- 5.0%; W-C15-C = 42.4 +/- 1.4%; W-C25-C = 44.1 +/- 2.3%; W-W-C = 50.5 +/- 4.1%). The temperature at reperfusion correlated most strongly with infarct size (r = 0.72, p < 1 x 10(-12)). CONCLUSIONS Very mild hypothermia affords a significant cardioprotective effect. Temperature at the time of reperfusion most strongly correlates with the degree of myocardial salvage.

Cyclosporine Preserves Mitochondrial Morphology After Myocardial Ischemia/Reperfusion Independent of Calcineurin Inhibition

BACKGROUND Opening of the mitochondrial permeability transition pore (MPTP) has been shown to contribute to myocardial ischemia/reperfusion injury. We sought to demonstrate that the myocardial protective effect of inhibiting MPTP opening with cyclosporine A (CsA) results in stabilization of mitochondrial morphology and is independent of CsA-induced calcineurin inhibition. METHODS Thirty-seven rabbits were divided into three groups: control (n = 15), CsA (MPTP and calcineurin inhibitor, n = 12), or FK506 (calcineurin inhibitor, n = 10). Each group received a 1-hour infusion of either a saline vehicle, 25 mg/kg CsA or 1 mg/kg FK506. All animals underwent 30 minutes of regional ischemia and 3 hours of reperfusion. Myocardial infarct size was determined using Evans blue dye and triphenyltetrazolium chloride. In situ oligo ligation was used to assess apoptotic cell death. Transmission electron microscopy was used to quantitatively evaluate morphologic differences in the mitochondria between groups. RESULTS Infarct size in the CsA group (39% +/- 3%) was significantly reduced compared with the control group (60% +/- 2%, p < 0.001) and FK506 group (55% +/- 3%, p = 0.001). Apoptotic cell death was also attenuated in the CsA group (1.2% +/- 0.5%) compared with the control group (4.3% +/- 0.8%, p = 0.01) and FK506 group (4.1% +/- 0.9%, p = 0.05). Transmission electron microscopy revealed a preservation of normal mitochondrial morphology and a reduction in the percentage of disrupted mitochondria in the CsA group (20% +/- 7%) compared with the control group (53% +/- 12%) and FK506 group (47% +/- 9%). CONCLUSIONS Cyclosporine A-induced MPTP inhibition preserves mitochondrial morphology after myocardial ischemia/reperfusion and limits myocyte necrosis and apoptosis. These effects are independent of calcineurin inhibition.

Quantifying Acute Myocardial Injury Using Ratiometric Fluorometry

Early reperfusion is the best therapy for myocardial infarction (MI). Effectiveness, however, varies significantly between patients and has implications for long-term prognosis and treatment. A technique to assess the extent of myocardial salvage after reperfusion therapy would allow for high-risk patients to be identified in the early post-MI period. Mitochondrial dysfunction is associated with cell death following myocardial reperfusion and can be quantified by fluorometry. Therefore, we hypothesized that variations in the fluorescence of mitochondrial nicotinamide adenine dinucleotide (NADH) and flavoprotein (FP) can be used acutely to predict the degree of myocardial injury. Thirteen rabbits had coronary occlusion for 30 min followed by 3 h of reperfusion. To produce a spectrum of infarct sizes, six animals were infused cyclosporine A prior to ischemia. Using a specially designed fluorometric probe, NADH and FP fluorescence were measured in the ischemic area. Changes in NADH and FP fluorescence, as early as 15 min after reperfusion, correlated with postmortem assessment infarct size (r=0.695, p<0.01). This correlation strengthened with time (r=0.827, p<0.01 after 180 min). Clinical application of catheter-based myocardial fluorometry may provide a minimally invasive technique for assessing the early response to reperfusion therapy.

In Vivo Fluorometric Assessment of Cyclosporine on Mitochondrial Function During Myocardial Ischemia and Reperfusion

BACKGROUND Cyclosporine A (CsA) limits myocardial reperfusion injury and preserves mitochondrial integrity, but its influence on mitochondrial function has not been described in vivo. Auto-fluorescence of mitochondrial nicotinamide adenine dinucleotide and flavin adenine dinucleotide correlate with mitochondrial dysfunction. We hypothesized that CsA limits mitochondrial dysfunction and that fluorometry can quantify this influence. METHODS Seventeen rabbits were studied: untreated (UnT, n = 7), CsA preinfarction (CsAp, n = 6), and CsA on reperfusion (CsAr, n = 4). Animals underwent 30 minutes of myocardial ischemia and 3 hours reperfusion. Infarct size was determined by staining. Nicotinamide adenine dinucleotide and flavin adenine dinucleotide fluorescence was continually measured in the risk area. The redox ratio was calculated [flavin adenine dinucleotide(f)/(flavin adenine dinucleotide(f) + nicotinamide adenine dinucleotide(f))]. Electron microscopy evaluated mitochondria morphology. RESULTS The infarct size by group was 39.1% +/- 1.7% in CsAp, 39.1% +/- 1.7% in CsAr, and 53.4% +/- 1.9% in UnT (p < 0.001). During ischemia, the CsAp group demonstrated less hypoxic reduction, with the redox ratio decreasing to 75.6% +/- 4.1% of baseline. The UnT and CsAr groups deceased to 67.1% +/- 4.0% and 67.2% +/- 3.6%, respectively (p < 0.005). During reperfusion the UnT group redox ratio increased to 1.59 +/- 0.04 times baseline. This increase was blunted in the CsAp (1.17 +/- 0.04, p = 0.026) and CsAr (1.35 +/- 0.02, p = 0.056) groups. Electron microscopy revealed reduced mitochondrial disruption in CsAp (19.7% +/- 7.6%) and CsAr (18.1% +/- 7.1%) rabbits compared with UnT (53.3% +/- 12.5%). CONCLUSIONS Fluorometric spectroscopy can be used in vivo to quantitatively assess the time course of CsAs influence on the mitochondrial dysfunction associated with myocardial ischemia and reperfusion.

Sex-related resistance to myocardial ischemia-reperfusion injury is associated with high constitutive ARC expression

The female sex has been associated with improved myocardial salvage after ischemia and reperfusion (I/R). Estrogen, specifically 17beta-estradiol, has been demonstrated to mediate this phenomenon by limiting cardiomyocyte apoptosis. We sought to quantitatively assess the effect of sex, ovarian hormone loss, and I/R on myocardial Bax, Bcl-2, and apoptosis repressor with caspase recruitment domain (ARC) expression. Male (n = 48), female (n = 26), and oophorectomized female (n = 20) rabbits underwent 30 min of regional ischemia and 3 h of reperfusion. The myocardial area at risk and infarct size were determined using a double-staining technique and planimetry. In situ oligo ligation was used to assess apoptotic cell death. Western blot analysis was used to determine proapoptotic (Bax) and antiapoptotic (Bcl-2 and ARC) protein levels in all three ischemic groups and, additionally, in three nonischemic groups. Infarct size (43.7 +/- 3.2%) and apoptotic cell death (0.51 +/- 0.10%) were significantly attenuated in females compared with males (56.4 +/- 1.6%, P < 0.01, and 4.29 +/- 0.95%, P < 0.01) and oophorectomized females (55.7 +/- 3.4%, P < 0.05, and 4.36 +/- 0.51%, P < 0.01). Females expressed significantly higher baseline ARC levels (3.62 +/- 0.29) compared with males (1.78 +/- 0.18, P < 0.01) and oophorectomized females (1.08 +/- 0.26, P < 0.01). Males expressed a significantly higher baseline Bax-to-Bcl-2 ratio (4.32 +/- 0.99) compared with females (0.65 +/- 0.13, P < 0.01) and oophorectomized females (0.42 +/- 0.10, P < 0.01). I/R significantly reduced Bax-to-Bcl-2 ratios in males. In all other groups, ARC levels and Bax-to-Bcl-2 ratios did not significantly change. These results support the conclusion that in females, endogenous estrogen limits I/R-induced cardiomyocyte apoptosis by producing a baseline antiapoptotic profile, which is associated with estrogen-dependent high constitutive myocardial ARC expression.

Successful Surgical Removal of a Giant Interventricular Fibroma: Surgical Approach Without Ventriculotomy

A 14-month-old boy was transported to our hospital by ambulance because of cardiopulmonary arrest after the sudden onset of convulsions. He was resuscitated and transthoracic echocardiography showed a giant interventricular tumor. The cause of this episode was thought to be ventricular arrhythmias induced by the tumor. At operation, an incision line was confirmed by direct ultrasonography. The heart was incised directly on the interventricular septum. The tumor was carefully dissected and completely removed without entering the ventricular cavity. Histologic analysis revealed a fibroma. The patients postoperative course was uneventful, and he remains well without episodes of heart failure or ventricular arrhythmia.

Face in Profile of Right Ventricular Outflow Tract in Tetralogy of Fallot: A Morphometric Study from Right Ventriculography

Background: The tetralogy of Fallot (TOF) is comprised of an anterior deviation of the septal insertion of the cardiac infundibular septum that leads to four detrimental morphological features which include a narrowing of the right ventricular outflow tract. A precise morphology of the frontal architecture of the affected right ventricular outflow tract has not yet been described even though its reconstruction is a critical part of TOF repair. We hypothesized that blood flow through this tract narrowed from behind by an anteriorly deviated infundibular septum causes an anterior prominence compared to the normal heart. Methods: 51 cases of TOF versus 34 control cases of isolated ventricular septal defect (VSD) without pulmonary hypertension were reviewed by applying a geometric method to clarify cardiac morphology. We analyzed each triangle (AOP) and compared the data between the TOF and control groups, but our hypothesis was disproven as the TOF anterior faces were not anteriorly prominent. Results: Several angles were shortened on analysis. However, after geometric comparison of triangle AOP between groups, we found only very small visible differences in the overall shapes of the triangles. The relative heights of anterior prominence of the right ventricular outflow tract were nearly the same in both groups. Conclusions: An anteriorly deviated infundibular septum has no relationship with the anterior wall of the right ventricular outflow tract and that surgeons should expand the anterior wall of the right ventricular outflow tract forward to conform to the deviated infundibular septum during TOF repair to restore normal blood flow.

Congenital-idiopathic superficial femoral artery aneurysm in a 7-year-old child.

Superficial femoral artery aneurysm in children is distinctly uncommon, and usually results from infection, vasculitis, connective tissue disorder, or trauma. We report a 7-year-old girl who had multiple fusiform aneurysms of the right superficial femoral artery, with no evidence of related disorders. The patient successfully underwent aneurysm resection and femoral artery reconstruction with autogenous saphenous vein. Histologic examination revealed intimal thickening with fibroplasia without severe inflammatory infiltrates or cystic medial necrosis, suggesting a congenital-idiopathic arterial aneurysm. Three years after the procedure, the saphenous vein graft is fully patent and the patient is in good condition.