Cibenzoline attenuates coronary systolic reversal flow in a patient with hypertrophic obstructive cardiomyopathy: a case report

Effects of cibenzoline on coronary hemodynamics, especially systolic reversal flow, were assessed in a 53-year-old man with hypertrophic obstructive cardiomyopathy by coronary flow study using a Doppler guidewire. Intravenous administration of cibenzoline resulted in decreases in the pressure gradient (60 to 0mmHg) and systolic left ventricular pressure (162 to 126 mmHg), and an increase in systolic arterial pressure (102 to 132mmHg). Furthermore, the systolic reversal flow observed at baseline was markedly diminished following administration of cibenzoline. Therefore, we speculate that cibenzoline reduces ventricular wall stress by diminishing the left ventricular obstruction that occurs with compression of the intramyocardial arteries. Cibenzoline-induced attenuation of coronary systolic reversal flow may be associated with the effectiveness of cibenzoline for diminishing the left ventricular obstruction.

Elevated levels of brain natriuretic peptide as a predictor of impaired coronary endothelial function in patients with left ventricular remodeling

BACKGROUND

Plasma levels of brain natriuretic peptide (BNP) correlate with left ventricular remodeling, but the relationship between BNP induction and coronary function remains unclear.

OBJECTIVES

The present study assessed BNP production in response to left ventricular enlargement and investigated the relationship between BNP production and coronary vasodilating function in patients with left ventricular remodeling.

METHODS

Patients (n = 63) with normal or mildly diseased coronary arteries underwent Doppler flow study of the left anterior descending coronary artery. Vascular reactivity was examined using intracoronary acetylcholine, papaverine and nitroglycerin using a Doppler guidewire.

RESULTS

Left ventricular end-diastolic dimension was positively correlated with BNP (r = 0.45, p < 0.001) in all patients. BNP was significantly and inversely correlated with percentage change in coronary artery diameter induced by acetylcholine (r = -0.56, p < 0.001) but not by nitroglycerin (r = -0.20, p = 0.28) in patients with left ventricular end-diastolic dimension > or = 55 mm (n = 32). By contrast, BNP was not significantly correlated with percentage change in coronary artery diameter induced by either acetylcholine or nitroglycerin in patients with left ventricular end-diastolic dimension < 55 mm (n = 31). Further, BNP was not correlated with the percentage change in coronary blood flow induced by acetylcholine or by papaverine in patients with or without left ventricular remodeling.

CONCLUSIONS

The elevation in plasma BNP levels that occurs in association with left ventricular enlargement is a predictor of impaired endothelium-dependent vasodilation in conductance coronary arteries.

Effect of Right Ventricular Apex Pacing on the Tei Index and Brain Natriuretic Peptide in Patients with a Dual-Chamber Pacemaker

BACKGROUND

Asynchronous electrical activation induced by right ventricular apex (RVA) pacing can cause various abnormalities in left ventricular (LV) function, particularly in the context of severe LV dysfunction or structural heart disease. However, the effect of RVA pacing in patients with normal LV and right ventricular (RV) function has not been fully elucidated. The aim of this study was to characterize the effects of RVA pacing on LV and RV function by assessing isovolumic contraction time and isovolumic relaxation time divided by ejection time (Tei index) and by assessing changes in plasma brain natriuretic peptide (BNP).

METHODS

Doppler echocardiographic study and BNP measurements were performed at follow-up (mean intervals from pacemaker implantation, 44+/-75 months) in 76 patients with dual chamber pacemakers (sick sinus syndrome, n=30; atrioventricular block, n=46) without structural heart disease. Patients were classified based on frequency of RVA pacing, as determined by 24-hour ambulatory electrocardiogram (ECG) that was recorded just before echocardiographic study: pacing group, n=46 patients with RVA pacing>or=50% of the time, percentage of ventricular paced 100+/-2%; sensing group, n=30, patients with RVA pacing<50% of the time, percentage of ventricular paced 3+/-6%.

RESULTS

There was no significant difference in mean heart rate derived from 24-hour ambulatory ECG recordings when comparing the two groups (66+/-11 bpm vs 69+/-8 bpm). LV Tei index was significantly higher in pacing group than in sensing group (0.67+/-0.17 vs 0.45+/-0.09, P<0.0001), and the RV Tei index was significantly higher in pacing group than in sensing group (0.34+/-0.19 vs 0.25+/-0.09, P=0.011). Furthermore, BNP levels were significantly higher in pacing group than in sensing group (40+/-47 pg/mL vs 18+/-11 pg/mL, P=0.017). With the exception of LV diastolic dimension (49+/-5 mm vs 45+/-5 mm, P=0.012), there were no significant differences in other echocardiographic parameters, including left atrium (LA) diameter (35+/-8 mm vs 34+/-5 mm), LA volume (51+/-27 cm3 vs 40+/-21 cm3), LV systolic dimension (30+/-6 mm vs 29+/-7 mm), or ejection fraction (66+/-9% vs 63+/-11%), when comparing the two groups.

CONCLUSIONS

These findings suggest that the increase of LV and RV Tei index, LVDd, and BNP are highly correlated with the frequency of the RVA pacing in patients with dual chamber pacemakers.

Association of coronary shear stress with endothelial function and vascular remodeling in patients with normal or mildly diseased coronary arteries

BACKGROUND

The relationship between coronary remodeling, shear stress and endothelial function remains unclear.

OBJECTIVE

The present study investigated the effects of mechanical factors on structure and function of epicardial coronary arteries.

METHODS

Patients (group 1: %area stenosis<40%, n=55; or group 2: %area stenosis>or=40%, n=17) with a discrete mildly stenotic lesion (%diameter stenosis<30%) underwent intravascular ultrasound examination of the left anterior descending coronary artery for determination of vessel area, lumen area, plaque area, cross-sectional areas at reference segments, and remodeling index (the ratio of vessel area at the culprit lesion to vessel area at the proximal reference site). Further, vascular reactivity was examined using intracoronary administration of acetylcholine, papaverine, and nitroglycerin.

RESULTS

Vessel area significantly correlated with plaque area in both groups (r=0.65, P<0.0001 and r=0.85, P<0.0001). Group 1 showed significantly greater acetylcholine-induced percentage changes in coronary blood flow (67+/-70 vs. 16+/-75%, P<0.05) and coronary artery diameter (-7+/-18 vs.-32+/-31%, P<0.01) and also significantly smaller coronary wall shear stress (65+/-27 vs. 81+/-32 dynes/cm, P<0.05) than group 2. The percentage increase in coronary blood flow induced by acetylcholine was significantly and positively correlated with remodeling index in group 1 (r=0.64, P<0.0001) but not in group 2 (r=-0.03, P=0.90) and was also significantly and positively correlated with coronary wall shear stress in group 1 (r=0.46, P<0.001) but not in group 2 (r=-0.33, P=0.19).

CONCLUSIONS

Endothelium-dependent vasodilation in the resistance coronary artery correlates with remodeling via increased wall shear stress when target lesions %area stenosis is <40%.

Progression rate of ALSFRS-R at time of diagnosis predicts survival time in ALS

The authors calculated the progression rate (DeltaFS) using the total revised ALS Functional Rating Scale (ALSFRS-R) and symptom duration at diagnosis in 82 Japanese patients with ALS. Survival (death or tracheostomy) differed significantly with the DeltaFS and postdiagnostic period according to log-rank testing, but Cox proportional hazards modeling revealed no strong association between total ALSFRS-R and mortality, suggesting that the DeltaFS provides an additional predictive index beyond ALSFRS-R alone.

Identification of novel E2F1 target genes regulated in cell cycle-dependent and independent manners

The transcription factor E2F mediates cell cycle-dependent expression of genes important for cell proliferation in response to growth stimulation. To further understand the role of E2F, we utilized a sensitive subtraction method to explore new E2F1 targets, which are expressed at low levels and might have been unrecognized in previous studies. We identified 33 new E2F1-inducible genes, including checkpoint genes Claspin and Rad51ap1, and four genes with unknown function required for cell cycle progression. Moreover, we found three groups of E2F1-inducible genes that were not induced by growth stimulation. At least, two groups of genes were directly induced by E2F1, indicating that E2F1 can regulate expression of genes not induced during the cell cycle. One included Neogenin, WASF1 and SGEF genes, which may have a role in differentiation or development. The other was the cyclin-dependent kinase inhibitor p27(Kip1), which was involved in suppression of inappropriate cell cycle progression induced by deregulated E2F. E2F1-responsive regions of these genes were located more upstream than those of typical E2F targets and did not have typical E2F sites. These results indicate that there are groups of E2F1 targets, which are regulated in a distinct manner from that of typical E2F targets.

Flow-cytometric analysis on cytotoxic effect of thimerosal, a preservative in vaccines, on lymphocytes dissociated from rat thymic glands

There is a concern on the part of public health community that adverse health consequence by thimerosal, a preservative in vaccines for infants, may occur among infants during immunization schedule. Therefore, the cytotoxic action of thimerosal was examined on lymphocytes dissociated from thymic glands of young rats using a flow cytometer and respective fluorescent probes for monitoring changes in intracellular Ca2+ concentration ([Ca2+]i) and membrane potential, and for discriminating intact living cells, apoptotic living cells and dead cells. Incubation with thimerosal at 3 microM or more (up to 30 microM) for 60 min depolarized the membranes, associated with increasing the [Ca2+]i. Thimerosal at 30 microM induced an apoptotic change in membranes of almost all living cells. Furthermore, the prolonged incubation with 30 microM thimerosal induced a loss of membrane integrity, leading to cell death. Since the blood concentration of thimerosal after receiving vaccines is theoretically submicromolar, it may be unlikely that thimerosal affects lymphocytes of infants.

Reactive hyperemia following coronary balloon angioplasty, but not dipyridamole-induced hyperemia, predicts resolution of exercise-induced ST-segment depression

OBJECTIVES

To characterize delayed restoration of coronary blood flow following successful percutaneous transluminal coronary angioplasty (PTCA).

BACKGROUND

Delayed restoration of coronary blood flow following successful PTCA is common and likely the result of multiple factors. Temporary myocardial ischemia and dipyridamole administration both result in increased coronary blood flow, but by different mechanisms. The relationship between these phenomena and exercise-induced ST-segment depression after PTCA was investigated to determine if any correlation existed.

METHODS

Forty consecutive patients with single-vessel coronary artery disease underwent treadmill exercise testing before and after PTCA. The percentage change in coronary blood flow before and after 90 s balloon inflation was assessed. After a new steady state had been reached, dipyridamole was infused and changes in coronary blood flow were again determined. The relationship between changes in coronary blood flow and the presence of ST-segment depression during exercise testing after PTCA was determined.

RESULTS

Peak coronary blood flow induced by reactive hyperemia was significantly greater than that in the steady state after balloon inflation (48.5+/-38.8 compared with 15.1+/-13.2 ml/min, P<0.0001). Dipyridamole administration also resulted in significant increases in coronary blood flow (15.1+/-13.2 ml/min compared with 31.0+/-24.9 ml/min, P<0.0001). ST-segment depression after PTCA was significantly less than before (0.10+/-0.07 mV compared with 0.19+/-0.08 mV, P<0.001). Further, reactive hyperemia, but not dipyridamole-induced hyperemia, correlated with attenuation of exercise-induced ST-segment depression after PTCA (r=0.62, P<0.0001).

CONCLUSIONS

Reactive hyperemia following temporary coronary occlusion recreates local conditions associated with delayed resolution of myocardial ischemia following successful PTCA. Further, this phenomenon appears to be distinct from changes in coronary blood flow induced by dipyridamole.

Contribution of increased minimal coronary resistance and attenuated vascular adaptive remodeling to myocardial ischemia in patients with systemic hypertension and ventricular hypertrophy

This study assessed the impact of coronary vascular adaptive remodeling and coronary vascular reactivity on myocardial ischemia in patients with hypertension and left ventricular hypertrophy. Myocardial ischemia is associated with impaired endothelium-independent vasodilation of resistance coronary arteries and increased minimal coronary resistance. These changes may occur in association with lumen reduction caused by attenuated adaptive remodeling in response to plaque accumulation.

Serum inhibitors for human mast cell growth: possible role of retinol

BACKGROUND

In vitro culture systems have been used to study the physiological and pathological characteristics of human mast cells. However, there are some differences in proliferation and maturation of mast cells between fetal bovine serum (FBS)-containing and serum-deprived cultures. Accordingly, we attempted to identify circulating factor(s) affecting the development of human mast cells.

METHODS

We measured the serum levels of retinol and several cytokines. To elucidate the antiproliferative effects of the serum, a retinoic acid receptor (RARalpha) antagonist and neutralizing antibodies against cytokines were used.

RESULTS

Similar to FBS, human serum dose-dependently suppressed the growth of tryptase+ cells from CD34+ cord blood cells or 20-week cultured mast cells under stimulation with stem cell factor (SCF). The serum-mediated inhibition might be based on a decline in proliferation rate. Among inhibitors for mast cell growth, retinol and transforming growth factor (TGF)-beta1 were present at high levels in human serum. In contrast with anti-TGF-beta1 antibody, an RARalpha antagonist counteracted the serum-induced suppression of human mast cell proliferation.

CONCLUSIONS

Our results suggest that retinol and its derivatives act as a circulating regulator for human mast cell growth. The RARalpha antagonist may be a useful tool to obtain higher numbers of mast cells in FBS-containing cultures.

Advancing age is associated with diminished vascular remodeling and impaired vasodilation in resistance coronary arteries

BACKGROUND

Compensatory enlargement of the coronary arterial wall has been described in the early stages of native atherosclerosis. However, little is known about the specific effect of aging on this adaptive process in atherosclerosis. The purpose of the current study was to characterize the effects of advancing age on vascular remodeling and endothelium-dependent and -independent coronary vasodilation in patients without coronary artery disease risk factors.

METHODS

Twenty-six patients without coronary risk factors and with normal and mildly diseased coronary arteries were studied. Vessel, lumen and atherosclerotic plaque areas were evaluated by intravascular ultrasound and coronary flow response was assessed using papaverine and acetylcholine in the left anterior descending coronary artery.

RESULTS

There was a weak but significant correlation between plaque area and age (r = 0.29, P<0.01). Vessel area was also weakly but significantly correlated with age (r = 0.22, P<0.05). However, lumen area had no correlation with age. Vessel area in the younger group (<50 years) and the older group (> or =50 years) increased 1.64 and 0.55 mm2 for every 1 mm2 increase in plaque area (r = 0.62, P<0.0001 and r = 0.39, P<0.05, respectively). With regard to vascular reactivity, there was an inverse correlation between the percentage increases in coronary blood flow (CBF) evoked by acetylcholine and aging (r = -0.49, P<0.05). The percentage increases in CBF evoked by papaverine also inversely correlated with aging (r=-0.53, P<0.01). However, the percentage changes in coronary artery diameter evoked with acetylcholine did not correlate with aging.

CONCLUSION

This study suggests that endothelium-dependent and -independent vasodilation of the resistance coronary artery are impaired with advancing age, which may be in association with attenuated coronary vascular remodeling with aging.

Radical anion of isolable dialkylsilylene

By the reduction of an isolable dialkylsilylene, 2,2,5,5-[tetrakis(trimethylsilyl)]-1-silacyclopentane-1,1-diyl (1), with cesium, rubidium, potassium, sodium, and lithium 4,4'-di(tert-butyl)biphenylide in DME at low temperatures, the corresponding silylene radical anion 2 was generated as the first persistent silylene radical anion in solution and characterized by ESR spectroscopy. Radical anion 2 is rather stable at -70 degrees C in DME but decomposes rapidly at room temperature with a half-life time of ca. 20 min. The g-factor and 29Si hyperfine splitting constants (hfs's) of 2 are almost independent of the countercations, indicating that 2 exists as a free ion or a solvent-separated ion pair in a polar DME solution. A very small hfs due to the 29Si nucleus of the divalent silicon (3.0 mT) as well as a very large g-factor (2.0077) indicates that an unpaired electron is accommodated in the vacant 3ppi orbital of silylene 1.