[Calcium antagonists and insulin resistance]

Calcium antagonists have become available for the treatment of hypertension and ischemic heart diseases. Large clinical trials have demonstrated that calcium antagonists prevent cardiovascular mortality and morbidity. Epidemiologic studies have shown insulin resistance is an independent predict factor for cardiovascular outcome. Cardiovascular diseases, including hypertension, diabetes mellitus, and hyperlipidemia are associated with insulin resistance. Insulin resistance is an initial step in atherosclerosis, leading to increase in the incidences of cardiovascular outcome. From a clinical perspective, it is important to select an appropriate intervention which is effective in improving insulin resistance in cardiovascular diseases. In this review, we would like to focus on the effects of calcium antagonists on insulin resistance (insulin sensitivity).

Relationship between endothelial function in the coronary and brachial arteries

BACKGROUND

Endothelial dysfunction is the first step in the progression to atherosclerosis, but little is known regarding whether there is a correlation in endothelial function between the coronary and peripheral arteries.

HYPOTHESIS

We investigated the relationship between coronary and peripheral endothelial function.

METHODS

In 41 patients (mean age 63 years; 23 men, 18 women) with angiographically normal coronary arteries, changes in brachial artery diameter in response to hyperemic flow and sublingual nitroglycerin (NTG) were measured by high-resolution ultrasonography. During coronary angiography, acetylcholine (ACh, 3 and 30 microg/min) and NTG were infused into the left coronary ostium. The diameter of the coronary artery was quantitatively measured and coronary blood flow (CBF) was calculated by quantitative angiography and Doppler flow velocity measurements. Changes in these parameters in response to each drug infusion were expressed as the percent change from the baseline values.

RESULTS

Flow-mediated dilation (FMD) of the brachial artery was 5.0 +/- 3.5% and correlated positively not only with the change in coronary diameter (ACh at 30 microg/min, r = 0.31, p < 0.05) but also with the change in CBF (ACh at 3 microg/min, r = 0.39, p < 0.05; ACh at 30 microg/min, r = 0.46, p < 0.01). Multivariate analysis demonstrated that FMD was one of the factors associated with the changes in coronary diameter and CBF.

CONCLUSIONS

These results suggest that brachial endothelial function is associated with coronary endothelial function in patients with angiographically normal coronary arteries, suggesting that impairment of endothelial function may occur simultaneously in both coronary and peripheral arteries.

Amelioration of vascular endothelial dysfunction in obstructive sleep apnea syndrome by nasal continuous positive airway pressure--possible involvement of nitric oxide and asymmetric NG, NG-dimethylarginine

BACKGROUND

Asymmetric NG,NG-dimethylarginine (ADMA) is an endogenous inhibitor of endothelial nitric oxide (NO) synthase and its plasma concentration is elevated in patients with cardiovascular risk factors, including hyperlipidemia, hypertension, diabetes, and hyperhomocysteinemia. Obstructive sleep apnea syndrome (OSAS) has been attracting attention as a risk factor for cardiovascular disorders because it often accompanies hypertension, obesity, glucose impairment, and dyslipidemia, all of which are factors in metabolic syndrome and risk factors for cardiovascular disease.

METHODS AND RESULTS

In the present study, flow-mediated vasodilatation (FMD) of the brachial artery and plasma concentrations of ADMA were measured before and after nasal continuous positive airway pressure (nCPAP) therapy, which abrogates apnea, in 10 male patients aged 36-69 years old, who were given a diagnosis of OSAS by polysomnography. The percent FMD (%FMD) improved significantly from 3.3+/-0.3% to 5.8+/-0.4% (p<0.01) and 6.6+/-0.3% (p<0.01), before, 1 week, and 4 weeks after nCPAP, respectively. At the same time, the plasma NOx concentrations, metabolites of NO, tended to increase, but the plasma ADMA concentration decreased inversely to %FMD and NOx. A negative correlation between %FMD and plasma ADMA concentration, and a positive correlation between %FMD and plasma NOx concentrations were observed.

CONCLUSION

Nasal CPAP improves endothelial function, in part by the decreasing ADMA concentration, thereby potentiating NO production.

Angiotensin II type I receptor blocker and endothelial function in humans: role of nitric oxide and oxidative stress

Recent large clinical trials have shown that angiotensin II type I receptor blockers (ARBs) reduce cardiovascular morbidity and mortality in patients with heart failure, acute myocardial infarction, and hypertension. However, the mechanism underlying antiatherogenic effects of ARBs remains unclear. The vascular endothelium is involved in the release of various vasodilators, including nitric oxide (NO), prostacyclin, and endothelium-derived hyperpolarizing factor as well as vasoconstrictors. NO plays an important role in the regulation of vascular tone, the inhibition of platelet aggregation, and the suppression of smooth muscle cell proliferation. Several investigators have reported impairment in endothelium-dependent vasodilation in the forearm, coronary, and renal vasculature in cardiovascular diseases, including hypertensive patients. Cardiovascular diseases are associated with alteration in endothelial function. Endothelial dysfunction is the initial step in the pathogenesis of atherosclerosis. Anti-renin-angiotensin system agents, angiotensin-converting enzyme (ACE) inhibitors improve endothelial function in patients with hypertension, diabetes mellitus, and coronary artery disease. It is well known that ACE inhibitors augment endothelium-dependent vasodilation through an increase in NO bioavailability, by an increase in NO production and a decrease in NO inactivation. ARBs are also thought to prevent cardiovascular complications through an augmentation of endothelial function. In this review, we focus on recent findings and putative mechanisms of the beneficial effects of ARBs on endothelial function.

Association of Helicobacter pylori infection with systemic inflammation and endothelial dysfunction in healthy male subjects

OBJECTIVES

The goal of the present study was to determine whether seropositivity to Helicobacter pylori (HP), Chlamydia pneumoniae (CP), and cytomegalovirus (CMV) is associated with systemic inflammation and endothelial dysfunction in healthy male subjects.

BACKGROUND

Chronic infection with certain bacteria and viruses may play an important role in inflammation as the pathogenesis of atherosclerosis.

METHODS

The serum levels of immunoglobulin G antibodies to HP, CP, CMV, high-sensitivity C-reactive protein, soluble intercellular adhesion molecule-1, and soluble vascular cell adhesion molecule-1 were determined in 81 healthy Japanese men (40 +/- 10 years of age). High-frequency ultrasonographic imaging of the brachial artery was used to study endothelium-dependent (flow-mediated vasodilation) and endothelium-independent (nitroglycerin-induced) vasodilation.

RESULTS

Prevalences of seropositive antibodies to HP, CP, and CMV were 67.9%, 61.7%, and 56.8%, respectively. Infection with HP, CP, or CMV had no relationship with age, blood pressure, or level of serum glucose, lipid, or soluble vascular cell adhesion molecule-1. The levels of C-reactive protein and soluble intercellular adhesion molecule-1 were significantly higher, and flow-mediated vasodilation was significantly lower in subjects with seropositive antibodies to HP than in subjects with seronegative antibodies to HP. Endothelium-independent vasodilation was similar in both groups.

CONCLUSIONS

Chronic infection with HP may be involved in the development of the atherosclerosis via endothelial dysfunction and systemic and vascular inflammation.

The Nicorandil-Induced Vasodilation in Humans Is Inhibited by Miconazole

Nicorandil, N-(2-hydroxyethyl)-nicotinamide nitrate, exerts its vasodilatory effects by opening ATP-sensitive potassium (K-ATP) channels and by acting as the exogenous nitric oxide (NO). It is not clear, however, whether the actions of other endothelium-dependent vasodilators, such as NO, endothelium-derived hyperpolarizing factor (EDHF), and prostaglandins, contribute to nicorandil-induced vasodilation in the vasculature in humans. We evaluated forearm blood flow (FBF) response to intraarterial infusion of nicorandil alone and in the presence of glibenclamide, a K-ATP channel inhibitor, N(G)-monomethyl-L-arginine, an NO synthase inhibitor, indomethacin, a cyclooxygenase inhibitor, or miconazol, a cytochrome P-450 inhibitor, in 24 healthy male subjects. FBF was measured using strain-gauge plethysmography. Infusion of nicorandil significantly increased the FBF response in a dose-dependent manner. Intraarterial infusion of glibenclamide attenuated nicorandil-induced vasodilation (160.9 +/- 21.2% versus 90.2 +/- 19.4%, P < 0.01), and miconazole also attenuated the FBF response to nicorandil (160.9 +/- 21.2% versus 66.1 +/- 9.2%, P < 0.001). N-monomethyl-L-arginine or indomethacin did not alter the FBF response to nicorandil. These findings suggest that nicorandil causes vasodilation in forearm circulation in humans, at least in part through a pathway that is dependent on K-ATP channels and cytochrome P-450, but not on endogenous NO and prostaglandins. EDHF may contribute to nicorandil-induced vasodilation in humans.

Forearm endothelial function and bone mineral loss in postmenopausal women

It is widely believed that the vasculature plays an important role in bone remodeling. We investigated the relationship between forearm endothelial function and bone mass in the lumbar spine in early postmenopausal women without a history of smoking or diabetes mellitus. We studied the forearm resistance artery endothelial function in 110 Japanese women-52 postmenopausal women with normal spinal bone mineral density (BMD), 36 postmenopausal women with osteopenia, and 22 osteoporotic postmenopausal women. Forearm blood flow (FBF) during reactive hyperemia and after sublingual nitroglycerin (NTG) administration was measured by strain-gauge plethysmography. BMD of the lumbar spine (L2-L4) was measured by dual-energy X-ray absorptiometry. After adjustment for age, body mass index, years since the start of menopause, and basal FBF, women with osteoporosis had a lower maximal FBF response to reactive hyperemia (28.4 +/- 3.8 mL/min per 100 mL tissue) than those with normal BMD (39.8 +/- 2.8 mL/min per 100mL tissue) or osteopenia (35.6 +/- 2.5 mL/min per 100mL tissue) (P = 0.029). A significant increase in serum angiotensin-converting enzyme (ACE) activity (P = 0.042) and a significant decrease in the serum concentrations of nitrite/nitrate (P = 0.041) were noted in osteoporotic women compared to women with normal BMD or osteopenia. The present findings suggest that postmenopausal women with low BMD, especially those with osteoporosis, have impaired endothelial function in the forearm resistance arteries.

Vascular function in patients with lower extremity peripheral arterial disease: a comparison of functions in upper and lower extremities

Peripheral arterial disease (PAD) is caused by atherosclerosis. Assessment of endothelial function in patients with PAD has been limited to that in forearm circulation in previous studies. The purpose of this study was to evaluate vascular function in upper and lower extremities in patients with PAD and to determine the relationship between the ankle-brachial pressure index (ABPI) and endothelial function in forearm and leg circulation. Forearm blood flow (FBF) and leg blood flow (LBF) responses to reactive hyperemia and sublingual administration of nitroglycerin (NTG) were measured using strain-gauge plethysmography in 57 PAD patients and 24 control patients. LBF during reactive hyperemia was significantly less in PAD patients than in control patients (p<0.001). FBF during reactive hyperemia in PAD patients was similar to that in control patients. NTG-induced vasodilation in upper and lower extremities was similar in the two groups. There was a significant relationship between the maximal LBF response to reactive hyperemia and the ABPI in both the patients with PAD and control patients (r=0.384, p<0.001), whereas maximal FBF response to reactive hyperemia was not correlated with ABPI (r=0.182, p=0.12). These findings suggest that LBF response to reactive hyperemia is impaired in PAD patients compared with that in control patients. Impairment of vascular reactivity of leg circulation may occur before impairment of vascular reactivity of forearm circulation in PAD patients and may be a better indicator of the degree of PAD than impairment of vascular reactivity of forearm circulation.

Impact of Blood Pressure Variability on Cardiovascular Events in Elderly Patients with Hypertension

Blood pressure variability is one of the characteristic features of hypertension in the elderly. However, its clinical significance remains to be determined. We therefore examined the impact of blood pressure variability on the development of cardiovascular events in elderly hypertensive patients. A total of 106 consecutive hypertensive patients aged more than 60 years old (mean age, 73.9 +/- 8.1 years old; male, 54%), all of whom underwent 24-h ambulatory blood pressure monitoring, were followed up (median, 34 months; range, 3-60 months). During the follow-up period, 39 cardiovascular events were observed, including 14 cases of cerebral infarction and 7 cases of acute myocardial infarction. The coefficient of variation (CV) of 24-h systolic blood pressure (SBP) values was used as an index of blood pressure variability. The patients showed a mean CV value of 10.6%, and were divided into two groups according to this mean value as a cut-off point: a high CV group (n = 46) and a low CV group (n = 60). Although baseline clinical characteristics were similar in the two groups, Kaplan-Meier plots for event-free survival revealed that the rate of cardiovascular events was significantly higher in high CV group than in low CV group (p < 0.05). Cox's proportional hazards analysis showed that increased blood pressure variability (a high CV value of 24-h SBP) was an independent predictive variable for cardiovascular events. The CV value of daytime SBP and the SD value of both 24-h SBP and daytime SBP also had positive correlations with the onset of cardiovascular events. These results suggest that increased blood pressure variability may be an independent risk factor for cardiovascular events in elderly hypertensive patients.

Apolipoprotein E phenotype affects the malondialdehyde-modified LDL concentration and forearm endothelial function in postmenopausal women

OBJECTIVE

We investigated whether the apolipoprotein E (apo E) phenotype affects the serum concentration of malondialdehyde-modified low-density lipoprotein (MDA-LDL) or forearm endothelial function in postmenopausal women.

PATIENTS AND MEASUREMENTS

Individuals were divided into three groups according to their apo E phenotype: E2 (E2/2 and E2/3, n = 12); E3 (E3/3, n = 71); and E4 (E3/4 and E4/4, n = 27). The serum concentrations of lipids and MDA-LDL were measured. Forearm blood flow during reactive hyperaemia and after sublingual nitroglycerin administration was measured by strain-gauge plethysmography.

RESULTS

The serum concentrations of total and LDL cholesterol were significantly higher in the E4 group than in the E2 group (P < 0.05) or in the E3 group (P < 0.05). The serum apo B concentration was significantly higher in the E4 group than in the E2 group (P < 0.05). The serum concentrations of high density lipoprotein (HDL) cholesterol and nitrite/nitrate were significantly lower in the E4 group than in the E2 group (P < 0.05). Other lipid concentrations did not differ in the three groups. The serum MDA-LDL concentration was highest in the E4 group, and was lowest in the E2 group (E2: 91.1 +/- 6.9 IU/l, E3: 112.3 +/- 5.9 IU/l, E4: 128.8 +/- 9.9 IU/l; P < 0.05). The forearm blood flow response to reactive hyperaemia was lowest in the E4 group, and highest in the E2 group (E2: 52.2 +/- 5.8 ml/min per 100 ml tissue, E3: 40.7 +/- 1.7 ml/min per 100 ml tissue, E4: 33.4 +/- 2.4 ml/min per 100 ml tissue; P < 0.05). The forearm blood flow changes in response to nitroglycerine were similar between all three groups.

CONCLUSIONS

The apo E phenotype affects the serum MDA-LDL concentration and forearm endothelial function in postmenopausal women.

Effect of edaravone, a novel free radical scavenger, on endothelium-dependent vasodilation in smokers

The forearm blood flow (FBF) responses to acetylcholine and to sodium nitroprusside were evaluated before and after administration of edaravone in 10 smokers and 10 nonsmokers. FBF response to acetylcholine was lower in smokers than in nonsmokers. The vasodilatory effects of sodium nitroprusside were similar in both groups. Co-infusion of edaravone increased the FBF response to acetylcholine in smokers, but did not affect the FBF response to acetylcholine in nonsmokers. The administration of N(G)-monomethyl-l-arginine abolished edaravone-induced augmentation of the FBF response to acetylcholine in smokers. The antioxidative agent edaravone increases nitric oxide mediated vasodilation through a decrease in oxidative stress.

Exercise and endothelial function: role of endothelium-derived nitric oxide and oxidative stress in healthy subjects and hypertensive patients

Recent epidemiologic studies have shown that aerobic exercise, one of lifestyle modifications, reduces cardiovascular morbidity and mortality in the general population. However, the mechanisms underlying the anti-atherogenic and anti-hypertensive effects of exercise remain unclear. Hypertension is associated with alteration in endothelial function mediated through reduced nitric oxide (NO) bioavailability. Endothelial dysfunction is an early feature of atherosclerosis and vascular diseases in humans. Exercise training has been shown to improve endothelial function in animal models of hypertension and in patients with essential hypertension. These findings suggest that endothelial dysfunction in hypertension is reversible. Lifestyle modifications including exercise are expected to prevent cardiovascular complications through an augmentation of endothelial function in hypertensive patients. It is thought that exercise increases NO production and decreases NO inactivation, leading to an increase in NO bioavailability. In this review, we will focus on recent findings and on possible mechanisms underlying the beneficial effects of exercise on endothelial function in patients with hypertension.

Exercise and endothelial function: role of endothelium-derived nitric oxide and oxidative stress in healthy subjects and hypertensive patients

Recent epidemiologic studies have shown that aerobic exercise, one of lifestyle modifications, reduces cardiovascular morbidity and mortality in the general population. However, the mechanisms underlying the anti-atherogenic and anti-hypertensive effects of exercise remain unclear. Hypertension is associated with alteration in endothelial function mediated through reduced nitric oxide (NO) bioavailability. Endothelial dysfunction is an early feature of atherosclerosis and vascular diseases in humans. Exercise training has been shown to improve endothelial function in animal models of hypertension and in patients with essential hypertension. These findings suggest that endothelial dysfunction in hypertension is reversible. Lifestyle modifications including exercise are expected to prevent cardiovascular complications through an augmentation of endothelial function in hypertensive patients. It is thought that exercise increases NO production and decreases NO inactivation, leading to an increase in NO bioavailability. In this review, we will focus on recent findings and on possible mechanisms underlying the beneficial effects of exercise on endothelial function in patients with hypertension.

Caveolin-1, Id3a and two LIM protein genes are upregulated by estrogen in vascular smooth muscle cells

Estrogen has diverse effects on the vasculature, such as vasodilation, endothelial growth and inhibition of vascular smooth muscle cell (VSMC) proliferation and migration. However, little is known about the genes that are regulated by estrogen in the vascular wall. Wistar rats were ovariectomized or sham-operated (Sham group), and 2 weeks after the operation, were subjected to subcutaneous implantation of placebo pellets (OVX + V group) or estradiol pellets (OVX + E group). Endothelium-denuded aortic tissue was examined 2 weeks after implantation. By applying high-density oligonucleotide microarray analysis, the expression of approximately 7000 genes was analyzed. Among the genes with different expression levels between the OVX + E group and the OVX + V group, those that have been reported to be expressed in the vasculature or muscle tissue, were chosen. Finally, four genes, caveolin-1, two LIM proteins (enigma and SmLIM) and Id3a, were identified. Microarray as well as real-time polymerase chain reaction showed that the expression levels of these genes were significantly higher in the OVX + E group than in the OVX + V group. To clarify whether estrogen directly upregulates these genes in the vascular wall, Northern blot analysis was performed using cultured rat VSMC. Addition of 100 nmol/L estradiol for 24 hours increased the mRNA levels of all four genes. Although the precise mechanism remains unclear, regulation of these genes by estrogen might contribute to its effect on VSMC.

Relation between C reactive protein concentrations and coronary microvascular endothelial function

OBJECTIVE

To determine how C reactive protein (CRP), a sensitive marker of inflammation, is related to coronary endothelial function.

DESIGN

Changes in quantitative coronary angiographic findings and Doppler flow velocity measurements in response to locally infused acetylcholine were assessed.

SETTING

Tertiary cardiology centre.

PATIENTS

46 patients with angiographically normal coronary arteries were divided into groups with normal (< or = 3 mg/l) or increased (> 3 mg/l) CRP concentrations.

INTERVENTIONS

Acetylcholine (3 and 30 microg/min) was infused into the left coronary ostium for two minutes.

MAIN OUTCOME MEASURES

Percentage change in diameter of epicardial coronary arteries and coronary blood flow (CBF) in response to acetylcholine; and correlations between these parameters and serum CRP concentrations.

RESULTS

15 patients had increased CRP concentrations. The change in coronary artery diameter induced by acetylcholine infusion was similar between the groups but the increase in CBF induced by acetylcholine was smaller in patients with increased CRP concentrations (54.9% v 139.4% with acetylcholine 30 microg/min, p = 0.0030). Multivariate analysis identified increased CRP concentration as independently associated with attenuated CBF response to acetylcholine at 30 microg/min (p = 0.0078, R2 = 0.434).

CONCLUSIONS

These findings suggest that inflammation appears to be associated with impaired coronary endothelial function in resistance but not conduit vessels. The data suggest a close relation between chronic vascular inflammation and endothelial dysfunction in atherosclerosis.

Matrix metalloproteinase-9 contributes to human atrial remodeling during atrial fibrillation

OBJECTIVES

The purpose of this study was to determine the relationship between matrix metalloproteinases (MMPs)-1, -2, and -9, and tissue inhibitors of metalloproteinases (TIMP)-1 and the atrial structural remodeling during atrial fibrillation (AF).

BACKGROUND

Matrix metalloproteinases, a family of proteolytic enzymes and TIMPs, regulate the extracellular matrix turnover in cardiac tissue.

METHODS

Tissue samples were obtained from 25 patients without a history of AF (regular sinus rhythm [RSR]) and 13 patients with AF (paroxysmal AF: 6, chronic AF 7) undergoing cardiac operations. We performed a western blotting analysis of the MMP-1, -2, and -9, and quantitatively analyzed the expression of the MMP-9 and TIMP-1 by real time polymerase chain reaction and ELISA. The localization of the MMP-9 was investigated by in situ zymography and immunohistochemistry.

RESULTS

The active form of the MMP-9 was significantly increased in the AF group in comparison to that in the RSR group (p < 0.05), but there were no differences between the groups in the protein level of the latent form of the MMP-9 and active and latent forms of the MMP-1 and MMP-2. We also demonstrated that the expression of the MMP-9 was significantly more increased in the atria of the AF group than in that of the RSR group for both the messenger ribonucleic acid (mRNA) (AF: RSR; 1: 1.5) and protein levels (AF: RSR; 3.9 +/- 1.3 : 1.5 +/- 0.4 ng/mg atrium). The expression level of the MMP-9 was also higher in the PAF group than in the RSR group, however, the diameter of the left atrium was similar in both groups. The gelatinase activity and left atrium diameter were positively correlated (p < 0.05, R = 0.766). The relative expression of the mRNA for the monocyte chemoattractant protein-1 was higher in the AF group than in the RSR group. Immunohistochemical analysis revealed that the MMP-9 was distributed within the perivascular area and under the epicardium of the atria.

CONCLUSIONS

We clearly showed that the expression of the MMP-9 increased in fibrillating atrial tissue, which may have contributed to the atrial structural remodeling and atrial dilatation during AF.

Tooth loss is associated with an increased risk of hypertension in postmenopausal women

Tooth loss has been associated with an increased risk of vascular diseases such as coronary heart disease and cerebrovascular disease. Little is known whether hypertension is an important factor linking 2 phenomena in postmenopausal women. We compared an incidence of hypertension and traditional risk factors for vascular diseases between 2 age-matched groups: 67 postmenopausal women with missing teeth and 31 without missing teeth. In addition to blood pressure, serum concentration of total cholesterol, high- and low-density lipoprotein cholesterol and triglycerides, plasma angiotensin-converting enzyme activity, plasma angiotensin II concentration, plasma renin activity, and resting heart rate were measured as traditional risk factors for vascular diseases. Subjects without missing teeth had significantly lower diastolic blood pressure than did subjects with missing teeth (P=0.021). The former tended to have lower systolic blood pressure than did the latter (P=0.058). There were no significant differences in other variables between subjects with and without missing teeth. The odds ratio of having hypertension in subjects with missing teeth was 3.59 (95% confidence interval, 1.10 to 11.7) after adjustment of obesity, hypercholesterolemia, and hypertriglyceridemia. Our results suggest that hypertension may be an important factor linking tooth loss and an increased risk of vascular diseases in postmenopausal women.

Autologous bone-marrow mononuclear cell implantation improves endothelium-dependent vasodilation in patients with limb ischemia

BACKGROUND

Patients with limb ischemia were associated with endothelial dysfunction. The purpose of this study was to determine whether autologous bone-marrow mononuclear cell (BM-MNC) implantation improves endothelial dysfunction in patients with limb ischemia.

METHODS AND RESULTS

We evaluated the leg blood flow (LBF) response to acetylcholine (ACh), an endothelium-dependent vasodilator, and sodium nitroprusside (SNP), an endothelium-independent vasodilator, before and after BM-MNC implantation in 7 patients with limb ischemia. LBF was measured with a mercury-filled Silastic strain-gauge plethysmograph. The number of BM-MNCs implanted into ischemic limbs was 1.6x10(9)+/-0.3x10(9). The number of CD34+ cells included in the implanted BM-MNCs was 3.8x10(7)+/-1.6x10(7). BM-MNC implantation improved the ankle-brachial pressure index (0.33+/-0.21 to 0.39+/-0.17, P=0.06), transcutaneous oxygen pressure (28.4+/-11.5 to 36.6+/-5.2 mm Hg, P=0.03), and pain-free walking time (0.8+/-0.6 to 2.9+/-2.2 minutes, P=0.02). After BM-MNC implantation, LBF response to ACh was enhanced (19.3+/-6.8 versus 29.6+/-7.1 mL/min per 100 mL; P=0.002). The vasodilatory effect of SNP was similar before and after BM-MNC implantation.

CONCLUSIONS

These findings suggest that BM-MNC implantation augments endothelium-dependent vasodilation in patients with limb ischemia.

[Oxidative stress, reactive oxygen species]

Hypertension is a risk factor for cardiovascular and cerebrovascular outcome. Hypertension is associated with oxidative stress. Alteration in endothelial function is an initial step in the pathogenesis of atherosclerosis. A balance between ambient levels of super oxide and released nitric oxide(NO) plays an important role in the maintenance of endothelial function. It is well known that reactive oxygen species, including hydroxy radicals, directly scavenge NO and produce toxic peroxynitrite. Angiotensin II and mechanical stress generate the reactive oxygen species through the activation of NADH/NADPH oxidase in hypertension. Several investigators have shown that oxidative stress is involved in enhanced vascular growth, vascular inflammation, and impaired endothelium-dependent in hypertension. In this review, we would like to explain the role of oxidative stress in hypertensive organ damages.

Response of the left anterior descending coronary artery to acetylcholine in patients with chest pain and angiographically normal coronary arteries

Because atherosclerotic plaque burden affects the likelihood of plaque rupture, it is important to determine the presence and extent of atherosclerotic plaque. We hypothesized that endothelial dysfunction becomes more prominent with development of atherosclerotic plaque; therefore, we examined the relation between coronary endothelial dysfunction and the presence of atherosclerotic plaque. In 36 patients with normal coronary arteries, acetylcholine (ACh; 3 and 30 microg/min) and nitroglycerin were infused into the left coronary ostium, and the diameter of the left anterior descending (LAD) coronary artery was quantitatively measured in response to each drug. The plaque burden was measured in the same segment using intravascular ultrasonography. The plaque burden was 31.2 +/- 2.1% and correlated inversely with changes in coronary diameter induced by 3 microg/min of ACh (r = -0.754, p <0.0001), 30 microg/min of ACh (r = -0.552, p = 0.0005), and nitroglycerin (r = -0.531, p = 0.0009). Multivariate regression analysis showed that the change in coronary diameter induced by 3 microg/min of ACh was associated with plaque burden, independent of the effects of nitroglycerin-induced dilation. Receiver-operating characteristics analysis demonstrated that a cut-off value for the change in coronary diameter induced by 3 microg/min of ACh for predicting a plaque burden of >30% was 0%, with a sensitivity of 0.82 and a specificity of 0.95. These findings suggest that coronary endothelial dysfunction is correlated with atherosclerotic plaque burden, indicating that atherosclerotic plaque may be detected based on coronary endothelial function as assessed by low-dose ACh infusion.

Mnk1 is required for angiotensin II-induced protein synthesis in vascular smooth muscle cells

Angiotensin II (Ang II) stimulates protein synthesis in vascular smooth muscle cells (VSMCs), possibly secondary to regulatory changes at the initiation of mRNA translation. Mitogen-activated protein (MAP) kinase signal-integrating kinase-1 (Mnk1), a substrate of ERK and p38 MAP kinase, phosphorylates eukaryotic initiation factor 4E (eIF4E), an important factor in translation. The goal of the present study was to investigate the role of Mnk1 in Ang II-induced protein synthesis and to characterize the molecular mechanisms by which Mnk1 and eIF4E is activated in rat VSMCs. Ang II treatment resulted in increased Mnk1 activity and eIF4E phosphorylation. Expression of a dominant-negative Mnk1 mutant abolished Ang II-induced eIF4E phosphorylation. PD98059 or introduction of kinase-inactive MEK1/MKK1, but not SB202190 or kinase-inactive p38 MAP kinase, inhibited Ang II-induced Mnk1 activation and eIF4E phosphorylation, suggesting that ERK, but not p38 MAP kinase, is required for Ang II-induced Mnk1-eIF4E activation. Further, dominant-negative constructs for Ras, but not for Rho, Rac, or Cdc42, abolished Ang II-induced Mnk1 activation. Finally, treatment of VSMCs with CGP57380, a novel specific kinase inhibitor of Mnk1, resulted in dose-dependent decreases in Ang II-stimulated phosphorylation of eIF4E, protein synthesis, and VSMC hypertrophy. In summary, these data demonstrated that (1) Ang II-induced Mnk1 activation is mediated by the Ras-ERK cascade in VSMCs, and (2) Mnk1 is involved in Ang II-mediated protein synthesis and hypertrophy, presumably through the activation of translation-initiation. The Mnk1-eIF4E pathway may provide new insights into molecular mechanisms involved in vascular hypertrophy and other Ang II-mediated pathological states.

Ghrelin improves endothelial dysfunction through growth hormone-independent mechanisms in rats

Ghrelin is a novel growth hormone (GH)-releasing peptide which was isolated from the stomach. We have reported that ghrelin causes vasorelaxation in rats through GH-independent mechanisms. We investigated whether ghrelin improves endothelial dysfunction. Ghrelin was subcutaneously administered to GH-deficient rats for three weeks. After isolation of the thoracic aorta, aortic ring tension was measured to evaluate vasorelaxation. Acetylcholine-induced vasorelaxation was impaired in GH-deficient rats given placebo compared to that in normal rats given placebo. GH-deficient rats treated with ghrelin, however, showed a significant increase in the maximal relaxation as compared with those given placebo. This improvement by ghrelin was inhibited by N(G)-nitro-L-arginine methyl ester, a nonselective nitric oxide synthase (NOS) inhibitor. Western blot analysis demonstrated that treatment with ghrelin increased endothelial NOS (eNOS) expression in the aorta of GH-deficient rats. These results suggest that administration of ghrelin improves endothelial dysfunction and increases eNOS expression in rats through GH-independent mechanisms.

[Infant case and adult case of scimitar syndrome with lung sequestration]

We present 2 cases of Scimitar syndrome with lung sequestration, 1 of which is infant case and the other is adult. A 3-month-old baby was transferred to our hospital because of severe heart failure. Cardiac ultrasonography and angiography revealed atrial septal defect and lung sequestration. Because of critical condition, she underwent emergency operation. After the operation of abnormal lung resection, her general condition improved. We emphasize that the prognosis is influenced by operation timing. A 20-year-old female was admitted for atrial septal defect. We diagnosed Scimitar syndrome and lung sequestration as the result of close examinations. We carried out definitive operations of the closure of atrial septal defect, the correction of partially anomalous pulmonary venous return and the resection of malformed lung. This adult case is popular one of Scimitar syndrome.