The relationship between lipoprotein-associated phospholipase A2 with cardiovascular risk factors in testosterone deficiency.

OBJECTIVE: Lipoprotein-associated phospholipase A2 (Lp-PLA2) which is believed to play a role in atherosclerotic inflammatory process due to its function in hydrolysis of phospholipids and release of pro-inflammatory products, is considered as a novel biomarker for vascular risk. In this study we aimed to investigate the alterations in Lp-PLA2 and its relationship with other cardiovascular risk factors in patients with testosterone deficiency. MATERIAL AND METHODS: Forty hypogonadic male and 30 healthy male aged between 18-50 years were enrolled in this study. Height-weight, waist-to-hip circumference, body mass index (BMI) blood pressure, and body fat measurements were performed in all subjects. Blood glucose, albumin, total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides, high sensitive C-reactive protein (hs-CRP), apo-A1, apo-B, fibrinogen, insulin, total testosterone, sex hormone binding globulin (SHBG), small dense low-density lipoprotein (sd-LDL), paraoxonase 1, oxidized low-density lipoprotein (ox-LDL) and Lp-PLA 2 values were measured. Free and bioavailable testosterone levels were calculated. Data management was carried out with the statistical program SAS Version 9.2. Statistical evaluations were performed using Analysis of Variance (ANOVA), Kruskal-Wallis test, Wilcoxon test, correlation analysis and chi-square analysis. P values <0.05 were considered statistically significant. RESULTS: In patients with hypogonadism, significant increase in Lp-PLA2 levels were accompanied with risk factors of atherosclerosis, such as increase in total cholesterol, apo-B, sd-LDL, weight, BMI, body fat percentage, and decrease in paraoxonase 1 levels. Although the differences were not significant, similarly ox-LDL, hs-CRP, triglyceride, LDL-cholesterol levels were found to be higher in patients with hypogonadism compared to the control group. The mean level of Lp-PLA2 was the highest when compared with the group of secondary hypogonadism with the lowest testosterone level. CONLUSION: Our study has demonstrated that the testosterone deficiency increases cardiovascular risk via its effects on lipid metabolism and Lp-PLA2 can be used to assess this risk.

Do cardiac risk factors affect the homocysteine and asymmetric dimethylarginine relationship in patients with coronary artery diseases?

OBJECTIVES: Elevated homocysteine (Hcy) concentrations have been shown to be a risk factor for atherosclerotic vascular disease and thrombosis. Increased asymmetric dimethylarginine (ADMA) levels have been implicated in the pathogenesis of numerous conditions affecting the cardiovascular system. In this study, the influence of cardiovascular risk factors and other variables on Hcy and ADMA relationship in patients with coronary artery disease (CAD) was investigated. DESIGN AND METHODS: Seventy-five patients with CAD were divided into three tertiles according to their Hcy levels. The effect of age, gender, blood pressure, lipid profile, renal function, and the presence of diabetes, insulin resistance, heart failure, inflammation, overweight, smoking and severity of coronary atherosclerosis on Hcy and ADMA relationship was evaluated. RESULTS: ADMA concentrations of patients in the middle and highest Hcy tertiles were significantly higher than the patients in the lowest tertile. When ADMA concentrations were adjusted for demographic, clinical and laboratory variables, the significant differences in ADMA concentrations between the tertiles were preserved. ADMA levels positively correlated with Hcy. Homocysteine levels positively correlated with serum creatinine and NT-proBNP concentrations and negatively correlated with glomerular filtration rates. Stepwise multiple regression analysis revealed Hcy as the unique predictor of ADMA levels. CONCLUSION: Homocysteine concentration has an effect on ADMA levels. There is a strong correlation between Hcy and ADMA. Cardiovascular risk factors do not have an influence on this relationship.

Fibroblast growth factor-19 levels in type 2 diabetic patients with metabolic syndrome.

This study aimed to examine fibroblast growth factor-19 (FGF-19) in type 2 diabetic (T2DM) patients with metabolic syndrome (MetS) and to evaluate the relationship between FGF-19 and other cardiovascular risk factors, such as atherogenic index of plasma (AIP) and hsCRP. 26 T2DM patients with MetS and 12 healthy controls were enrolled in the study. Serum FGF-19 levels were measured by sandwich ELISA, and compared with other cardiovascular risk factors; lipid profile, AIP, glucose, HbA1c, and hsCRP. AIP was calculated as log (TG/HDL-c). The median (1-3.quartile) FGF-19 levels in T2DM patients with MetS and healthy controls were 122.90 (108.63-237.60) pg/ml and 293.45 (153.64-370.31) pg/ml, respectively (P=0.003). Patients were also grouped by body mass index (BMI) <30 kg/m(2) (n=13) and ≥30 kg/m(2) (n=13) with median (1-3.quartile) FGF-19 values 168.70 (113.54-275.77) pg/mL and 115.89 (97.94-200.40) pg/mL, respectively (P=0.007). Significant negative correlations were found between FGF-19 and BMI, triglyceride, log (TG/HDL-c), hsCRP, and HbA1c (r=-0.526, P=0.001; r=-0.327, P=0.05; r=-0.312, P=0.05; r=-0.435, P=0.006; r=-0.357, P=0.028, respectively). We showed that FGF-19 levels are low in T2DM patients with MetS. The negative relationship between FGF-19 and several known cardiovascular risk factors such as TG, log (TG/HDL-c), hsCRP and HbA1c in diabetic patients with MetS suggests that FGF-19 can be used as a contributing marker.

Serum N-terminal-pro-B-type natriuretic peptide (NT-pro-BNP) levels in hyperthyroidism and hypothyroidism.

E Natriuretic peptides represent a novel diagnostic tool in the assessment of heart failure. N-terminal-pro-B-type natriuretic peptide (NT-proBNP), a member of the natriuretic peptid family, is produced and released from cardiac ventricles. Changes in cardiac functions are observed in thyroid dysfunctions. The aim of this study was to assess the changes in serum NT-proBNP levels and to evaluate impact of thyroid hormones on serum NT-proBNP in patients with hyperthyroidism and hypothyroidism. Serum NT-proBNP levels were measured in 21 patients with hyperthyroidism and in 24 patients with hypothyroidism and compared with 20 healthy control subjects. Patients without cardiac disease were included into the study as well. Serum NT-proBNP levels were measured by electrochemiluminescence immunoassay. Serum NT-proBNP levels were higher in hyperthyroid patients than in hypothyroid patients and in control subjects, with mean values of 239.03 +/- 47.33, 45.97 +/- 13.48, 55.57 +/- 13.01 pg/ml, respectively (p < 0.0001). Serum NT-proBNP and thyroid hormones were correlated in all patients. Moreover, there was a significant positive correlation between serum NT-proBNP and serum free T4 (FT4) levels (r = 0.549, p = 0.012) in hyperthyroidic patients. Multiple regression analyses demonstrated that increasing FT4 was independently associated with a high serum NT-proBNP levels, whereas heart rate was not in hyperthyroid patients. Serum NT-proBNP levels are higher in the hyperthyroid state as compared with the hypothyroid and euthyroid state. Thyroid dysfunction affects serum NT-proBNP levels, possibly influencing the secretion of the peptide. Therefore, thyroid function has to be considered when evaluating high serum NT-proBNP levels in patients without cardiac dysfunction.

Impact of renal function or folate status on altered plasma homocysteine levels in hypothyroidism.

Hyperhomocysteinemia is an independent risk factor for coronary, peripheral and cerebrovascular diseases. Moderately elevated total homocysteine (tHcy) levels have been reported in patients with overt hypothyroidism. Plasma tHcy concentration is affected by several physiological factors and is elevated under conditions of impaired folate and cobalamin status and in renal failure. The aim of this study was to assess plasma tHcy concentrations and to evaluate the role of potential determinants of plasma tHcy levels in hypothyroid patients. Fasting plasma tHcy, serum homocysteine-related vitamins folate and vitamin B(12), serum cystatin C (CysC) and creatinine, were determined in 22 hypothyroid patients and compared with 25 healthy control subjects. Creatinine clearance (CCr) was calculated using the Cockroft-Gault formula. Plasma tHcy levels were determined by HPLC with fluorescence detection and serum CysC by automated particle enhanced immunoturbidimetry. Plasma tHcy, creatinine levels were significantly higher, and serum CysC levels, and creatinine clearance values were lower in hypothyroid patients than in control subjects. Folate levels were lower in hypothyroidic group compared to the control group. There were no differences in vitamin B(12) levels between hypothyroid and control groups. Positive correlation was noted between tHcy and creatinine levels in hypothyroid patients (r = 0.596); however, an inverse correlation was found between tHcy and folate levels (r = -0.705) in hypothyroid patients. In conclusion, tHcy was increased in hypothyroidism, and this increase was more strongly associated with changes in serum folate than in serum creatinine and CysC, suggesting an altered folate status.

Effects of L-arginine and L-carnitine in hypoxia/reoxygenation-induced intestinal injury.

BACKGROUND: This study was designed to show the role of oxidative stress, nitric oxide and glutathione-related antioxidant enzymes in hypoxia/reoxygenation (H/R)-induced intestinal injury model in mice and to evaluate the potential benefits of arginine and carnitine supplementation. METHODS: A total of 28 young Balb/c mice were divided into four groups: Group 1 (untreated) was given physiological saline before the experiment; group 2 H/R mice were supplemented with L-arginine; group 3 H/R mice were given L-carnitine for 7 days; and group 4 mice served as controls. At the end of day 7, H/R injury was induced and intestinal tissue malondialdehyde (MDA), nitrate levels and glutathione peroxidase (GSH-Px), glutathione reductase (GR) and glutathione-S-transferase (GST) activities were measured. RESULTS: MDA levels were higher in the untreated animals than in the other three groups. MDA levels were higher in the L-arginine-treated animals than in the L-carnitine-treated animals. Nitrate levels were found to be increased in the L-arginine-treated group when compared to the controls. GSH-Px and GR activities were increased in the untreated, the L-arginine and the L-carnitine-treated H/R groups when compared to the control group. GST activities were indifferent between the groups. CONCLUSIONS: Oxidative stress contributes to the pathogenesis of H/R-induced intestinal injury. The glutathione redox cycle may have a crucial role in the H/R-induced intestinal injury. L-arginine and L-carnitine supplementations ameliorate the histological evidence of H/R-induced intestinal injury and decrease lipid peroxidation but do not alter the glutathione-related antioxidant enzyme activities.

Amlodipine and glutathione cycle in hypercholesterolaemia.

OBJECTIVE: Effects of amlodipine on lipid peroxidation and alterations in glutathione and related enzymes in blood and aortic tissue were investigated in a cholesterol-induced atherosclerotic rabbit model. METHODS AND RESULTS: New Zealand white male rabbits were fed with regular chow (group I), chow supplemented with I% cholesterol (group II), regular chow plus amlodipine 5 mg/kg/day p.o. (group III) and I% cholesterol diet supplemented with amlodipine (group IV) for 8 weeks. Cholesterol, malondialdehyde (MDA), reduced glutathione (GSH), oxidized glutathione (GSSG), glutathione peroxidase (GSH-PX) and glutathione reductase (GSH-Rd) were determined in blood samples drawn before and after the experimental period. Aortic tissue was examined morphologically for atherosclerotic changes and tissue cholesterol, MDA, GSSG, GSH-PX, GSH-Rd and glutathione-S-transferase (GST) were measured. After 8 weeks, blood cholesterol, MDA, GSSG and GSH-PX were elevated in groups II and IV; GSH was reduced in group IV; MDA levels were higher in group II than in group IV. Aortic tissue investigations revealed higher cholesterol and MDA concentrations in group II than in group IV. Morphological examination of aortic tissues exhibited endothelial disarrangement and lipid deposition in group II. Histopathological alterations related to atherogenesis were less in group IV than in group II. CONCLUSIONS: Amlodipine reduced the increase in oxidative stress by inhibiting excessive MDA production. Accelerated glutathione redox cycle activity of erythrocytes from animals supplemented with amlodipine suggests that this drug may reduce oxidative stress by enhancing the glutathione system. However, this drug does not seem to affect the glutathione redox cycle in the aortic tissue.

Pentoxifylline does not prevent hypoxia/reoxygenation-induced necrotizing enterocolitis. An experimental study.

Hypoxia/reoxygenation (H/R)-induced intestinal injury plays a significant role in the development of necrotizing enterocolitis (NEC). We experimentally explored the effect of pentoxifylline (PTX) on an NEC model. Twenty-one newborn rabbits were divided into three groups: group 1 (control), group 2 (H/R) and group 3 (H/R + PTX). Five minutes of reoxygenation following 5 min of hypoxia was performed three times a day during 3 days. Before each H/R procedure in the H/R + PTX group, the rabbits were treated with PTX 25 mg/kg intraperitoneally. Animals were sacrificed on the third day and ileum samples were taken for histopathological examination and biochemical enzyme studies [superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione S-transferase (GST)]. There was a significant difference in the grade and number of the intestinal lesions between controls and the H/R and H/R + PTX groups (p < 0.001), but no significant difference was found between the H/R and the H/R + PTX groups (p > 0.05). Intestinal SOD, GR and GST activities in the H/R and H/R + PTX groups were significantly higher than in the control group (p < 0.05); however, there was no significant difference between the H/R and H/R + PTX groups (p > 0.05). Significantly reduced GPx activity was found in the H/R and H/R + PTX groups compared with the controls (p < 0.05). No significant difference in GPx activity existed between the H/R group and the H/R + PTX group (p > 0.05). Ischemia/reperfusion injury was responsible for mediating hypoxia-induced intestinal necrosis in NEC and PTX pretreatment did not have a protective effect on NEC.

Association between serum paraoxonase activity and oxidative stress in acute coronary syndromes.

OBJECTIVE: The oxidation of low-density lipoprotein (LDL) is believed to have a central role in atherogenesis. Under oxidative stress not only LDL, but all other serum lipids are exposed to oxidation. High-density lipoprotein (HDL)-associated paraoxonase (PON1) was shown to inhibit LDL and HDL oxidation. We investigated the relationship between PON1 and oxidative stress in acute myocardial infarction and unstable angina in a comparative fashion. METHODS AND RESULTS: Activities of PON1, concentrations of malondialdehyde (MDA), lipids and lipoproteins were measured in patients (38 subjects with acute myocardial infarction and 33 subjects with unstable angina pectoris) and in age- and sex-matched controls (32 subjects). Serum PONI activity was significantly lower in patients than in controls (p < 0.001). Patients had significantly increased serum MDA concentrations (p < 0.001) and there were strong negative correlations (p < 0.001) between serum PON1 and MDA levels in the acute myocardial infarction group (r = -0.673), in the unstable angina pectoris group (r = -0.868) and in healthy controls (r = -0.778). Serum HDL-cholesterol (HDL-C) concentrations were lower in patients than controls (p < 0.05). No correlation was observed between PON1 and HDL-C levels in patients or controls. Apo A I concentrations were significantly lower in the patient groups (p < 0.01), but were insignificant between patients with AMI and UAP. Apo A-I and PON1 levels did not show any correlation. Apo B concentrations were lowest in the healthy controls, higher in the UAPgroup and highest in the AMI group (p < 0.001). In the acute myocardial infarction group LDL/apo B ratio was lower than in healthy controls and in the UAP group, suggesting smaller LDL particle size. CONCLUSIONS: Results of this study indicate that lower serum PON1 activity is associated with oxidative stress and the activity of PON1 is not related to HDL-cholesterol.

Serum and urinary nitric oxide in Type 2 diabetes with or without microalbuminuria: relation to glomerular hyperfiltration.

BACKGROUND: Glomerular hyperfiltration is considered as one of the pathophysiological mechanisms for the development of diabetic nephropathy. Oxidative stress is enhanced in patients with diabetes mellitus. Reportedly, nitric oxide (NO) might be involved in the pathogenesis of hyperfiltration. We investigated the relationship between hyperfiltration and NO system, and malondialdehyde (MDA) levels in Type 2 diabetics with/without microalbuminuria. METHODS: In 39 microalbuminuric, 29 normoalbuminuric Type 2 diabetic patients and 32 healthy controls, serum creatinine, nitrite, nitrate, urinary microalbumin, nitrite, nitrate, plasma MDA and estimated glomerular filtration rate (EGFR) values, calculated according to the Cockcroft and Gault formula, were recorded. RESULTS: Serum and urine NO levels were higher in both microalbuminurics and normoalbuminurics than controls. There were no significant differences in EGFR between groups. However, hyperfiltration was determined in 31% of normoalbuminurics and 20% of microalbuminurics. Serum and urine NO levels were higher in patients with hyperfiltration. Plasma MDA levels were significantly elevated in both microalbuminurics and normoalbuminurics when compared with controls. Serum glucose and microalbuminuria were positively correlated in microalbuminuric diabetics. Serum NO levels were also positively correlated with EGFR in both normoalbuminurics and microalbuminurics. HbA1c levels were positively correlated with both urinary albumin excretion and plasma MDA levels in normoalbuminuric diabetics. CONCLUSIONS: Hyperglycemia is associated with an increased NO biosynthesis and lipid peroxidation. Increased oxidative stress may contribute to the high NO levels in Type 2 diabetes. Furthermore, the high NO levels may lead to hyperfiltration and hyperperfusion, which in turn leads to an increase in urinary albumin excretion and thus causes progression of nephropathy in early Type 2 diabetes.

Effects of the calcium channel blocker amlodipine on serum and aortic cholesterol, lipid peroxidation, antioxidant status and aortic histology in cholesterol-fed rabbits.

Reactive oxygen metabolites and oxidized fatty acids are proinflammatory and are involved in the pathophysiology of atherosclerosis. Amlodipine, a unique third-generation dihydropyridine-type calcium channel blocker, seems to exert atheroprotective effects through its antioxidant properties related to its chemical structure and independent of its calcium channel-blocking effect. In this study, the interactions of amlodipine with major cellular antioxidants were investigated in order to elucidate the mechanisms underlying its atheroprotective effects. New Zealand white male rabbits were fed regular chow (group 1), chow with 1% cholesterol (group 2), regular chow plus 5 mg/kg/day amlodipine per os (group 3) and 1% cholesterol plus amlodipine (group 4) for 8 weeks. Total cholesterol, malondialdehyde (MDA) and vitamin E concentrations and catalase and superoxide dismutase (SOD) activities were determined in blood drawn before and after the experimental period. Aortic tissue was examined for atherosclerotic changes and aortic total cholesterol, MDA, catalase and SOD were determined. At the end of the 8-week treatment period, serum total cholesterol and plasma MDA were elevated in groups 2 and 4. In group 2, serum vitamin E and plasma SOD diminished (p < 0.05) and catalase increased (p < 0.05). In group 4, SOD activity increased at the end of treatment. MDA levels were lower and plasma SOD activities were higher in group 4 than in group 2. Aortic tissue investigations revealed higher total cholesterol and MDA concentrations and catalase activities in group 2 than in group 4, and the highest tissue SOD activity was recorded in group 4 (p < 0.05 for all comparisons). Morphological examination of aortic tissues exhibited endothelial disarrangement and lipid deposition in group 2. Histopathological alterations related to atherogenesis were less in group 4 than in group 2. Amlodipine seems to exert atheroprotective effects by reducing aortic cholesterol accumulation and blood and aortic lipid peroxidation, enhancing SOD activity both in blood and aortic tissue and suppressing the consumption of vitamin E. On the other hand, the suppression of catalase activity in blood and the aorta interferes with the drug's well-known antioxidant effects.

Comparison of the effects of dietary saturated, mono-, and n-6 polyunsaturated fatty acids on blood lipid profile, oxidant stress, prostanoid synthesis and aortic histology in rabbits.

BACKGROUND/AIMS: To compare the effects of saturated, monounsaturated and polyunsaturated n-6 fatty acid-enriched diets on the development of atherosclerosis and thrombosis in New Zealand white male rabbits, 3- to 6-month-old animals were supplemented daily (10 g/100 g diet) with butter (n = 8), olive oil (n = 8) or corn oil (n = 8) by oral administration for 7 weeks. METHODS: Total cholesterol (TC), HDL- (HDL-C) and LDL-cholesterol (LDL-C), triglycerides (TG), apolipoprotein A-1 (ApoA-1), apolipoprotein B (ApoB), lipid peroxides as thiobarbituric acid-reactive substances (TBARS), thromboxane B2 (TXB2) and 6-ketoprostaglandin F(1alpha) (6-ketoPGF(1alpha)) concentrations were determined in blood samples drawn before and after each group was fed the different dietary regimens. Histological examination was performed on the aortic tissues. RESULTS: After 7 weeks, TC, ApoB and TXB2 increased significantly (p < 0.05) in the butter-fed animals compared to pre-experimental concentrations. Olive oil administration lead to a significant (p < 0.05) decrease in TC and ApoB levels. The corn oil-enriched diet decreased TC, LDL-C concentrations, TC/HDL-C ratios and 6-ketoPGF(1alpha) (stable metabolite of prostacyclin-PGI2; p < 0.05 for all) but increased TBARS levels and TXB2/6-ketoPGF(1alpha) ratios. Light microscopic findings were in accordance with these biochemical alterations. CONCLUSION: Although effective in lipid lowering, corn oil increased oxidant stress as evidenced by increased TBARS and induced endothelial damage which lead to a reduction in PGI2 synthesis and consequently to an increase in the TXB2/6-ketoPGF(1alpha) ratio. Olive oil administration did not induce oxidant stress and it had no affect on PGI2 and TXB2 levels which are implicated in platelet aggregation. These findings suggest that oleic acid is more effective than linoleic acid in the protection of endothelial integrity.

Association between homocysteinemia and renal function in patients with type 2 diabetes mellitus.

Homocysteinemia is an independent risk factor for cardiovascular disease, but information on its association with type 2 diabetes and mild renal dysfunction is limited. Plasma total homocysteine (tHcy) concentration is partly determined by renal plasma clearance. Serum cystatin C (Cys C) concentration has been introduced as a marker of renal function, specifically as an indicator of glomerular filtration rate (GFR). The aim of this study was to explore the relationships among tHcy, creatinine clearance (Ccr), serum Cys C, and microalbuminuria in a population with type 2 diabetes. Fasting plasma tHcy, serum homocysteine-related vitamins (folate and vitamin B12), serum Cys C, serum creatinine, urine microalbumin, and creatinine clearance were determined in 75 type 2 diabetic patients and 40 healthy control subjects. The patients were assigned to two groups based on urinary albumin excretion (UAE): normoalbuminuric (NAU, UAE < 30 mg/24 hr, n = 35) and microalbuminuric (MAU, UAE 30-300 mg/24 hr, n = 40). Ccr was calculated using the Cockroft-Gault formula. Plasma Hcy levels were determined by HPLC with fluorescence detection and serum Cys C by automated particle enhanced immunoturbidimetry. Plasma tHcy levels were significantly higher in normoalbuminuric and microalbuminuric patients than in controls (10.64 +/- 0.53, 13.29 +/- 0.78, 6.91 +/- 0.37 mmol/L, respectively). Serum Cys C levels in microalbuminuric diabetics were higher than in normoalbuminurics and controls (1.36 +/- 0.06, 1.12 +/- 0.04, 1.10 +/- 0.06 mg/ L, respectively). Positive correlations were noted between tHcy and Cys C levels in normoalbuminuric and microalbuminuric diabetics (r = 0.72, r = 0.64, respectively). Homocysteine and creatinine concentrations were correlated in both diabetic groups (r = 0.89, r = 0.93, NAU and MAU, respectively). Elevated plasma total homocysteine concentrations in type 2 diabetics suggest an association between homocysteinemia and deterioration of renal function, evidenced by increased serum creatinine and Cys C, Ccr, and microalbuminuria. These findings implicate homocysteinemia in the relationship between diabetic nephropathy and cardiovascular complications of diabetes.