Susceptibility of apolipoprotein B-containing lipoproteins to oxidation and antioxidant status in acute coronary syndromes

BACKGROUND

Oxidized lipoproteins may play an important role in the pathogenesis of atherosclerosis, and it has been shown that antioxidants have a protective effect against the progression of atherosclerosis.

HYPOTHESIS

The aim of this study was to investigate the oxidative susceptibility of apolipoprotein B-containing lipoproteins and antioxidant status in patients with acute coronary syndromes and chronic stable angina pectoris.

METHODS

The study population included 70 patients with acute coronary syndromes (14 with recent acute myocardial infarction and 56 with unstable angina pectoris), 105 patients with stable angina pectoris, and 75 control subjects. In addition to conventional lipid and lipoprotein analysis, the susceptibility of apolipoprotein B-containing lipoproteins to in vitro oxidation (lag phase) and plasma vitamin E and total carotene levels was measured.

RESULTS

The lag phase was significantly shorter in patients with acute coronary syndromes (45 +/- 12 min) than in patients with stable angina pectoris (51 +/- 10 min) and in control subjects (58 +/- 9 min) (p < 0.0001). Both plasma vitamin E and total carotene levels were lowest in patients with acute coronary syndromes (1.11 +/- 0.32 mg/dl and 119 +/- 32 micrograms/dl, respectively), followed by patients with stable angina pectoris (1.25 +/- 0.37 mg/dl and 132 +/- 37 micrograms/dl) and then controls (1.52 +/- 0.31 mg/dl and 167 +/- 41 micrograms/dl).

CONCLUSIONS

These data suggest that there is an intense oxidative process and a lower antioxidant status in acute coronary syndromes. This may lead to plaque instability due to the activation of the inflammatory response in coronary atherosclerotic lesions.

Effect of N-acetylcysteine on oxidative stress and ventricular function in patients with myocardial infarction

Recent evidence suggests that postischemic myocardial dysfunction ("stunning") may be mediated by oxygen free radicals. Various studies have reported the beneficial effects of antioxidants in ischemia-reperfusion injury. The aim of this study was to assess the effect of N-acetylcysteine (NAC) treatment on oxidative stress, infarct size, and left ventricular (LV) function, as adjunct therapy in myocardial infarction (MI). Patients with acute MI received either 15 g NAC infused over 24 h (n = 15) or no NAC (n = 15), combined with streptokinase. Peripheral venous blood was serially sampled to measure creatine kinase (CK)-MB levels. Plasma malondialdehyde (MDA) level was measured at admission and after 4 and 24 h. Echocardiography was performed within 3 days of MI and after 3 months. At admission, plasma MDA levels were not different between the groups. In the NAC-treated patients plasma MDA levels decreased, whereas in the nontreated NAC patients MDA levels increased at 4 and 24 h (P < 0.01 and P < 0.001, respectively). Left ventricular ejection fraction was higher (P < 0.05) and LV end-systolic and end-diastolic diameters were lower (P < 0.001 and P < 0.001) in patients receiving NAC on day 3. Left ventricular wall motion score index was significantly lower in patients treated with NAC on day 3 (P < 0.05). Left ventricular diastolic parameters were not different whether patients were treated with NAC or not. No difference in reduction of infarct size was detected between the groups according to CK-MB levels. It was thus demonstrated that administration of NAC in combination with streptokinase significantly diminished oxidative stress and improved LV function in patients with acute MI. These encouraging results would justify the performance of a larger controlled study.

The relation between oxidant and antioxidant parameters and severity of acute coronary syndromes

OBJECTIVE

Acute coronary syndromes (ACS) encompass a continuum of cardiac ischaemic events, ranging from unstable angina pectoris (UA) to ST-segment elevation myocardial infarction (STEMI). Oxidative stress may play an important role in the pathogenesis of acute coronary diseases. In the present study, we examined the associations between lipid and protein susceptibility to oxidation and total sialic acid (SA) and antioxidant status and the severity of ACS as determined by having UA, non-STEMI or STEMI.

METHODS AND RESULTS

The study sample consisted of 102 patients with ACS and 45 controls. Malondialdehyde (MDA) as a marker of lipid peroxidation and protein carbonyls as a marker of protein oxidation were measured to show the susceptibility to oxidation. Antioxidant status was determined by measuring the carotenoids, vitamin C and vitamin E levels and paraoxonase and arylesterase activities. In addition to conventional lipid and lipoprotein analysis, MDA and vitamin E were quantitated by high-performance liquid chromatography. Total SA and other oxidant and antioxidant parameters were studied spectrophotometrically. As expected, patients had significantly higher total cholesterol, triacylglycerol, low-density lipoprotein cholesterol, lipoprotein (a), apolipoprotein (apo) B values and lower high-density lipoprotein cholesterol and apoAl values than controls. Our results demonstrated significant increases both in total SA levels and in indicators of oxidative stress in patients with ACS compared with the controls. However, antioxidant parameters were decreased in patients with ACS. When the patients were divided into groups with UA, non-STEMI and STEMI, respectively, total SA and oxidant parameters were significantly increased and antioxidant parameters were significantly decreased in going from UA to STEMI.

CONCLUSIONS

Our study shows gradually increased lipid and protein oxidation and total SA and gradually decreased antioxidant status when the conditions advance from UA to STEMI. These results indicate that these markers may be useful both in understanding plaque destabilization and in determination of risk stratification of patients. Also, measurement of these markers may provide a noninvasive window to study atherosclerotic lesions.

Sialic acid and oxidizability of lipid and proteins and antioxidant status in patients with coronary artery disease

The aim of this study was to investigate the possible relationship between serum total sialic acid (TSA) concentration, recently shown to be a cardiovascular risk factor, and lipid and protein oxidation and antioxidant status and the severity of coronary artery disease (CAD) according to the obstructive vessel number in patients. The study was carried out on a total of 200 patients (142 men and 58 women) who were hospitalized for elective coronary angiographic evaluation with complaint of typical angina pectoris. According to the results of angiography, 150 patients had angiographically proven CAD (CAD group) and 50 patients had a history suggestive of angina pectoris but normal coronary angiograms (control group). The CAD group was further divided into single-, double- and triple-vessel disease groups according to the number of vessels involved. Lipid parameters were determined by routine laboratory methods. Plasma malondialdehyde (MDA) and vitamin E concentrations were determined by high-performance liquid chromatography. TSA and other oxidant and antioxidant parameters were studied spectrophotometrically. Our results demonstrated significant increases both in TSA levels and in indicators of oxidative stress in the patients with CAD compared with the controls. However, antioxidant parameters were decreased in the patients with CAD. We found strong positive correlations between TSA and plasma MDA, Delta-MDA which represents the degree of oxidative modification of apolipoprotein B-containing lipoproteins, serum protein carbonyls and apolipoprotein B and weak correlations between TSA and low density lipoprotein cholesterol, triacylglycerol, paraoxonase, glutathione peroxidase (GPx), vitamin C and vitamin E. In conclusion, TSA is related to markers of lipid and protein oxidation, paraoxonase and GPx activities, vitamin C and E levels and the severity of CAD.

Effects of glucose-insulin-potassium solution added to reperfusion treatment in acute myocardial infarction

OBJECTIVE

Reperfusion treatment modalities used in the routine treatment protocols of acute myocardial infarction (AMI) were found to be ineffective in establishing the nutritional cellular reperfusion in the microvascular environment even they succeed to open the infarct related artery. Glucose-insulin-potassium (GIK) solution, which is presumed to stimulate the glycolytic pathway, is experimentally proven to be the most efficacious substrate for the preservation of energy production and therefore the myocardial viability, in the setting of acute ischemia.

METHODS

We compared, 54 patients who suffered AMI and received GIK solution (300 g glucose+50 IU crystallized insulin+80 mEq potassium chloride in one liter solution) in addition to conventional treatment (GIK group) with 27 patients who were traditionally treated (control group) for in-hospital and early-term (1 month) cardiac morbidity. We also compared the two groups in terms of heart rate variability (HRV).

RESULTS

Eight patients in the control group developed new-onset symptomatic congestive heart failure whereas only 5 patients in GIK group were found to have such a cardiac morbidity (p=0.01). Reduced HRV (<50 ms) was found in 3 patients of control group whereas no patient in GIK group had abnormal HRV (p=0.01).

CONCLUSION

The GIK solution decreased the incidence of new-onset symptomatic congestive heart failure and low HRV after myocardial infarction. Larger multicenter trials need to resolve the questions on the efficiency of metabolic intervention with GIK solution in acute myocardial infarction.

The effect of fenofibrate on serum paraoxonase activity and inflammatory markers in patients with combined hyperlipidemia

BACKGROUND

Lipid lowering therapy with statins is beneficial because of improvement in lipoprotein concentrations and additional pleiotropic effects. However, less is known about the pleotropic effect of fibrates.

AIM

To investigate the effects of fenofibrate therapy on inflammatory markers and serum paraoxonase activity in patients with combined hyperlipidemia in addition to their lipid lowering effects.

METHODS

Fifty patients (18 women, 32 men, mean age 50+/-8.7 years) with a history of combined hyperlipidemia and coronary artery disease were enrolled into the study. Serum lipids, inflammatory markers (high sensitivity C-reactive protein (hs-CRP) and fibrinogen levels) and paraoxonase levels were determined before and after two months of 250 mg per day of fenofibrate treatment.

RESULTS

Fenofibrate decreased plasma fibrinogen level by 41% (from 3.9+/-0.9 mg/dl to 2.3+/-0.48 mg/dl, p<0.0001) and hs-CRP level by 71% (from 1.28 mg/dl to 0.36 mg/dl; p<0.0001). Changes in hs-CRP levels were not correlated with the changes in lipid levels. Compared with baseline, serum paraoxonase level was significantly increased after fenofibrate treatment (from 200+/-77U/L to 232+/-82U/L; p<0.001). We found a significant correlation between changes in HDL cholesterol and paraoxonase activity after two months of treatment (r=0.46, p=0.018).

CONCLUSION

This study demonstrates that beyond improving lipids and lipoprotein levels, fenofibrate treatment increases paraoxonase activity and decreases inflammatory markers in patients with combined hyperlipidemia.

The effect of orlistat-induced weight loss on interleukin-6 and C-reactive protein levels in obese subjects

OBJECTIVE

Inflammation plays a major role in the pathogenesis of atherosclerosis. Obesity is an independent risk factor for cardiovascular disease, which may be mediated by increased secretion of proinflammatory cytokines by adipose tissue. The aim of this study is to investigate changes in the inflammatory markers interleukin-6 (IL-6) and high-sensitivity C-reactive protein (hs-CRP) during weight reduction with orlistat treatment in obese patients.

METHODS AND RESULTS

Thirty-six obese (BMI: 36.1 +/- 3.4 kg/m2) and II non-obese (BMI: 22.9 +/- 1.7 kg/m2) subjects were studied. IL-6 and hs-CRP levels were evaluated at baseline. In obese subjects after treatment of orlistat 120 mg three times daily for 6 months, IL-6 and hs-CRP levels were repeated. Levels of circulating IL-6 (p < 0.05) and hs-CRP (p < 0.01) were significantly higher in the obese group than in the non-obese group. Plasma IL-6 (r = 0.29 and p < 0.05) and CRP (r = 0.35 and p < 0.05) concentrations correlated positively with the level of obesity assessed by BMI at baseline. After 6 months of orlistat treatment in obese subjects, the mean weight of the patients decreased by 6.8 kg, the BMI by 3.2 kg/m2. Compared with baseline, weight loss was associated with significant reductions of IL-6 (p < 0.001) and hs-CRP (p < 0.001) levels.

CONCLUSION

In summary plasma IL-6 and hs-CRP levels were increased in obese patients. Orlistat-induced weight reduction was associated with decreasing levels of both IL-6 and hs-CRP in obese subjects. Because inflammatory mediators may be directly involved in atherogenesis, this would suggest that interventions to reduce IL-6 and CRP levels could be cardioprotective.

Myocardial performance and aortic elastic properties in elite basketball and soccer players: relationship with aerobic and anaerobic capacity

The aims of the present study were to examine the myocardial performance index and aortic elastic properties of athletes engaged in ball sports and to determine their relationships with aerobic and anaerobic characteristics. Standard M-mode and Doppler echocardiography, maximal oxygen uptake and 30 sec Wingate tests were performed for 32 elite male athletes (12 basketball and 20 soccer players) and 12 healthy sedentary volunteers. Data were analyzed by ANOVA and partial correlation coefficient tests. Absolute values of left ventricular internal diameter, left ventricular posterior wall and interventricular septum thicknesses in diastole were significantly (p < 0.05-0.01) greater in athletes than in controls. The left ventricular internal diameter corrected by body surface area was also greater (p < 0.05-0.01) in the athletes compared with the controls. Absolute and body surface area corrected left ventricular mass were significantly greater (p < 0.05-0.001) in athletes than in controls. Isovolumetric relaxation time was higher (p < 0.01) in soccer players than in controls. There were no significant differences among the groups for myocardial performance index and aortic elastic properties. Left ventricular mass index was poorly correlated (p < 0.01) with VO2max (r = 0.410), peak power (r = 0.439) and average power (r = 0.464) in the athletes. Poor correlations (r = 0.333-0.350, p < 0.05) were also observed between aortic elastic properties and average power in athletes. Myocardial performance index and aortic elastic properties are not different in athletes involved in this study compared with sedentary subjects. Aerobic and anaerobic capacities of the athletes used in this study are poorly explained by these resting echocardiographic findings. Key PointsLeft ventricular internal diameter, left ventricular posterior wall and interventricular septum thicknesses in diastole, and left ventricular mass were significantly greater in athletes than in controls.There were no remarkable differences in Doppler velocities and time intervals between athletes and controls.Myocardial performance index and aortic elastic properties are not different in athletes compared with sedentary subjects.Aerobic and anaerobic parameters of athletes are poorly explained by resting echocardiographic characteristics.VO2max and anaerobic power indices are variables that better determines left ventricular mass developed in ball sport specific training.

Lipid peroxides in obese patients and effects of weight loss with orlistat on lipid peroxides levels

OBJECTIVE

Obesity is a well-known risk factor of atherosclerosis. Recent studies showed that obesity is associated with enhanced lipid peroxidation. The aim of this study is to investigate the effect of weight reduction with orlistat treatment on lipid peroxidation levels. We assessed lipid peroxidation by measuring the concentration of plasma malondialdehyde (MDA).

DESIGN

A randomized, controlled, open-label 6-month study.

SUBJECTS

In total, 36 obese (body mass index (BMI) >30 kg/m2) and 11 healthy age-matched control subjects were enrolled in the study.

MEASUREMENTS

Fasting glucose, triglyceride, total cholesterol, HDL cholesterol and LDL cholesterol and MDA levels were measured in both groups. Obese subjects received orlistat, 120 mg three times daily together with hypocaloric diet. After 6 months of treatment laboratory tests were repeated.

RESULTS

MDA levels were significantly higher in obese patients than the control group (P<0.0001). After 6 months of treatment in obese subjects, the mean weight of the patients decreased by 6.8 kg, the BMI by 3.2 kg/m2. Plasma MDA levels were significantly reduced by weight loss from 2+/-0.77 to 0.89+/-0.41 nmol/ml (P<0.001). BMI correlated with MDA levels at baseline (r=0.6, P<0.0001). Changes in BMI was positively associated with plasma MDA level reduction (r=0.36, P<0.05).

CONCLUSION

These results indicate that obesity is associated with increases in endogenous lipid peroxides. Our data show that the indicator of lipid peroxidation-MDA-falls markedly in association with weight loss with orlistat. The demonstration of decreased free radical generation has important implications for oxidative mechanism underlying obesity-associated disorders.

[Lipoprotein (a) as a risk factor for coronary artery disease in women and elderly patients]

OBJECTIVE

The role of lipoprotein (a) [Lp(a)] as a risk factor for coronary artery disease (CAD) in women and elderly is not clear. In this study we assessed the relation between serum Lp (a) levels and CAD, taking into account the differences in sex and age.

METHODS

Lp (a) levels and other lipid variables were determined in 535 consecutive patients undergoing coronary angiography for chest pain evaluation. Among 535 patients, 163 patients had angiographically normal coronary arteries (70 men and 93 women) and 372 patients had significant coronary lesions at least one coronary artery (300 men and 72 women).

RESULTS

After adjustment for hypertension, smoking, diabetes, low density lipoprotein-cholesterol (LDL-C), triglycerides and high density lipoprotein-cholesterol (HDL-C), elevated Lp (a) was independently predictive for CAD in both sexes under 55 years old (odds ratio [OR]: 5.1, p < 0.01 for men and OR: 2.3, p < 0.05 for women). In patients more than 55 years old elevated Lp (a) was not associated with CAD for both sexes (OR: 1.3, p = NS for men and OR: 1.2, p = NS for women).

CONCLUSION

We did not find any relation between elevated Lp (a) concentrations and presence of angiographically detectable CAD both in men and women aged more than 55 years old. Our results suggest that elevated Lp (a) is an independent risk factor for premature CAD for both men and women.

Relation of functional capacity with the oxidative stress and antioxidants in chronic heart failure

Chronic heart failure is a common, disabling disorder with high mortality. Oxidative stress may have both functional and structural effects on the myocardium, leading to myocardial decompensation. In this study, the authors examined the relationship of oxidative stress and functional capacity in patients with varying degrees of heart failure. Fifty-one patients with chronic heart failure and 31 control subjects were studied. The functional capacity of patients was determined. Plasma malondialdehyde, vitamin E, and beta-carotene levels were measured. The malondialdehyde levels were significantly different between control subjects and heart failure patients (p=0.03). There was a positive correlation between patients' malondialdehyde levels and New York Heart Association functional class (r=0.59; p<0.0001). There was a negative correlation between the functional class and vitamin E and beta-carotene levels (r=20.43; p<0.0001 and r=20.25; p<0.01, respectively). These data demonstrate that oxidative stress is increased systemically in patients with chronic heart failure. It seems that this increase correlates with functional class. (c)2001 CHF, Inc.

Effects of fosinopril treatment on blood pressure during physical and mental stress test in essential hypertension

In this study the effects of once daily administration of 10 mg fosinopril on blood pressure response to mental and physical stress were evaluated in mild to moderate essential hypertension. A total of 25 patients (14 women, 9 men) with mild to moderate essential hypertension were enrolled in this study. Before the treatment and after 10 mg/day fosinopril treatment for 2 months, systolic and diastolic blood pressure and heart rate were recorded at rest and while performing a mental arithmetic test. In addition, exercise stress testing with Bruce protocol were performed before and after the treatment and systolic and diastolic blood pressure and heart rate were recorded at rest and during peak exercise. Statistical analysis were done by using the paired t-test. During the mental arithmetic test, systolic and diastolic blood pressure were significantly reduced (p < 0.005 and p < 0.001, respectively) after 2 months fosinopril treatment. Systolic and diastolic blood pressure were also significantly reduced during the exercise stress test (p < 0.005 and p < 0.05) after the treatment. Heart rate did not change during either the mental arithmetic or the exercise test. As a result, once daily 10 mg fosinopril may be effective in reducing blood pressure, not only at rest, but also during stressful situations.

Relation between lipoprotein (a) and in vitro oxidation of apolipoprotein B-containing lipoproteins

OBJECTIVES

To assess the relationship between lipoprotein (a) [Lp (a)] and lipoprotein oxidation in patients with coronary artery disease (CAD).

DESIGN AND METHODS

Oxidation of apolipoprotein (apo)B-containing lipoproteins, vitamin E, carotenoids, lipid-lipoprotein levels were determined in 171 CAD and 70 non-CAD subjects.

RESULTS

In CAD patients with Lp (a) concentrations >/= 30 mg/dL; total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), malondialdehyde (MDA), and apo B levels were significantly higher and lag-time and age were significantly lower than those of CAD patients with Lp (a) concentrations < 30 mg/dL. In non-CAD subjects with Lp (a) concentrations >/= 30 mg/dL; TC, LDL-C, and vitamin E levels were significantly higher and lag-time was significantly lower than those of non-CAD subjects with Lp (a) concentrations < 30 mg/dL. In CAD patients, Lp (a) correlated negatively with lag-time and positively with MDA levels. Lp (a) correlated negatively with lag-time and vitamin E levels in non-CAD subjects.

CONCLUSIONS

We have shown that plasma apo B-containing lipoproteins of both CAD and non-CAD subjects with Lp (a) levels >/= 30 mg/dL are more susceptible to in vitro oxidative modification than those of subjects with Lp (a) levels < 30 mg/dL. The relationship between Lp (a) and enhanced susceptibility of apo B-containing lipoproteins to oxidation, appears to support routine investigation of Lp (a).

Effect of successful coronary angioplasty and stent implantation on QT dispersion

BACKGROUND

QT dispersion (defined as maximal QT interval minus minimal QT interval), as assessed using the surface ECG, has been shown to reflect regional inhomogeneities in ventricular repolarization. The aim of this study was to show the effect of coronary revascularization, by successful coronary angioplasty or stent implantation, on QT dispersion.

METHODS

QT dispersion was defined on each ECG as the difference between the maximal and minimal measurements of QT interval. Of 135 patients studied, 52 patients underwent coronary angioplasty and 84 patients underwent stent implantation. Maximum and minimal QT interval and QT dispersion were measured using 12-lead electrocardiography before and 24 h after each successful procedure.

RESULTS

QT dispersion decreased from 51 +/- 12 ms at baseline to 37 +/- 10 ms 24 after the procedure (P < 0.001). Before the procedure, the QT dispersion of patients undergoing angioplasty and stent implantation was 50 +/- 13 and 52 +/- 10 ms, respectively. After the procedure, the QT dispersions were 34 +/- 9 and 38 +/- 10 ms, respectively (P < 0.001). QT dispersion was significantly lower in both groups after the procedure. No differences were observed between the QT dispersions of patients undergoing angioplasty and of those undergoing stent implantation.

CONCLUSIONS

Successful coronary angioplasty and stent implantation significantly reduced QT dispersion. The decreased QT dispersion may have been caused by improvements in myocardial perfusion and may be beneficial in reducing the likelihood of arrhythmias occurring.