Ana Vujovic

Evaluation of different formulas for LDL-C calculation

BackgroundFriedewalds formula for the estimation of LDL-C concentration is the most often used formula in clinical practice. A recent formula by Anandaraja and colleagues for LDL-C estimation still needs to be evaluated before it is extensively applied in diagnosis. In the present study we validated existing formulas and derived a more accurate formula to determine LDL-C in a Serbian population.MethodsOur study included 2053 patients with TG ≤ 4.52 mmol/L. In an initial group of 1010 patients, Friedewalds and Anandarajas formulas were compared to a direct homogenous method for LDL-C determination. The obtained results allowed us to modify Friedewalds formula and apply it in a second group of patients.ResultsThe mean LDL-C concentrations were 3.9 ± 1.09 mmol/L, 3.63 ± 1.06 mmol/L and 3.72 ± 1.04 mmol/L measured by a direct homogenous assay (D-LDL-C), calculated by Friedewalds formula (F-LDL-C) and calculated by Anandarajas formula (A-LDL-C), respectively in the 1010 patients. The Students paired t-test showed that D-LDL-C values were significantly higher than F-LDL-C and A-LDL-C values (p < 0.001). The Passing-Bablok regression analysis indicated good correlation between calculated and measured LDL-Cs (r > 0.89). Using lipoprotein values from the initial group we modified Friedewalds formula by replacing the term 2.2 with 3. The new modified formula for LDL-C estimation (S-LDL-C) showed no statistically significant difference compared to D-LDL-C. The absolute bias between these two methods was -0.06 ± 0.37 mmol/L with a high correlation coefficient (r = 0.96).ConclusionsOur modified formula for LDL-C estimation appears to be more accurate than both Friedewalds and Anandarajas formulas when applied to a Serbian population.

Does simultaneous determination of LDL and HDL particle size improve prediction of coronary artery disease risk

BackgroundAlterations in plasma lipoprotein subclass distribution affect the risk for coronary artery disease (CAD). However, it is unclear whether the determination of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) phenotypes may or may not improve the ability to predict CAD development.MethodsPolyacrylamide gradient (3–31%) gel electrophoresis was used to simultaneously determine size and distribution of lipoprotein subclasses in 181 CAD patients and 178 controls.ResultsMean LDL and HDL subclass sizes were significantly smaller in patients than in controls (p < 0.001). Multivariate logistic regression analysis showed that small dense LDL particles were independent CAD risk predictors (OR = 2.867, p < 0.01), even when adjusted for other traditional risk factors, while small HDL particles lost their significance after adjustment (OR = 2.071, p = 0.054). The area under the ROC curve for LDL (0.671) and HDL (0.643) particle size measurement demonstrated low clinical accuracy when compared to the combination of traditional lipid risk factor measurements.ConclusionsCAD is associated with the predominance of smaller LDL and HDL particles. However, simultaneous determination of these two lipoprotein phenotypes provides no additional power in discriminating CAD and non-CAD subjects, beyond that obtained by the traditional risk factors.

Hyperlipidemia, oxidative stress, and intima media thickness in children with chronic kidney disease.

BackgroundThe roles of dyslipidemia and oxidative stress in the early phases of atherosclerosis were tested in children with chronic kidney disease (CKD). Intima media thickness of common carotid arteries (cIMT) is used as a measure of early atherosclerosis.MethodsFifty-two pediatric CKD patients were enrolled in the study (10 with chronic renal failure [CRF], 22 with a renal transplant [RT], 20 with chronic hemodialysis (cHD) patients, and 36 healthy children (control group, CG). Lipid status, oxidative stress, and paraoxonase 1 (PON1) status were assessed. cIMT was measured by ultrasound, adjusted for age and sex, and presented as standard deviation scores (SDS).ResultsChildren with CKD had disturbed lipid content, which was most pronounced in cHD children, with higher free cholesterol and triglycerides compared with healthy children. Oxidative stress was markedly increased (malodialdehyde [MDA, μmol/L]: CRF 1.50 ± 0.26, RT 1.55 ± 0.40, cHD 1.77 ± 0.34, CG 0.97 ± 0.33, p < 0.001) and antioxidative defense was compromised (superoxide dismutase [SOD, U/L]: CG 120 ± 21, CRF 84 ± 25, RT 93 ± 12, cHD 119 ± 37, p < 0.001). Multiple linear regression analysis showed that a model that included disease duration, blood pressure, urea, lipid, and oxidative status parameters accounted for more than 90% of the variability of cIMT-SDS.ConclusionsEarly atherosclerosis in CKD children is caused, at least in part, by dyslipidemia and oxidative stress. Monitoring of vessel wall changes, along with assessment of oxidative stress status and high density lipoprotein (HDL) functionality is necessary to ensure better therapeutic strategies for delaying atherosclerotic changes in their asymptomatic phase.

A hazardous link between malnutrition, inflammation and oxidative stress in renal patients.

BACKGROUND Atherosclerosis is the main cause of mortality in end stage renal disease (ESRD) patients. DESIGN AND METHODS Malnutrition, inflammation and diminished paraoxonase activity were used to calculate the sum of risk factors for atherosclerosis development in a cohort of 141 chronic renal disease patients. Kaplan-Meier survival analysis was implemented to assess risk of death. RESULTS Kaplan-Meier analysis (Log rank=12.06, P=0.0072) showed higher risk of death with increasing number of risk factors in haemodialysis patients. CONCLUSIONS Malnutrition in combination with inflammation and oxidative stress is associated with higher mortality in patients on long-term haemodialysis.

Longitudinal changes in PON1 activities, PON1 phenotype distribution and oxidative status throughout normal pregnancy.

The purpose of the present study was to determine changes in plasma paraoxonase-1 activity (an indicator of paraoxonase phenotype) throughout normal pregnancy and its relationship with maternal oxidative stress status. The frequencies of the paraoxonase-1 phenotype in the studied population were determined using a two-substrate (paraoxon/diazoxon) activity method. As a parameter of oxidative stress status we measured the redox balance. Paraoxonase-1 activity significantly decreased at gestational week 32. In addition, the lipid profile was more atherogenic. Redox balance was significantly increased across gestational weeks. There were independent direct associations between maternal smoking habits before pregnancy, glucose concentrations and redox balance with PON1 activity in the third trimester. This study shows that pregnancy is followed by a decrease in PON1 activity and increased risk for development of cardiovascular diseases. We conclude that changes in paraoxonase-1 status during pregnancy are associated with maternal oxidative stress status and smoking habits.

Association of the atherogenic index of plasma and oxidative stress status with weight gain during non-complicated pregnancy.

Abstract Background: Pregnancy is a stressful condition linked with altered lipid profile, increased oxidative stress and increased inflammation processes. The purpose of the present study was to determine the associations between those alterations with increased weight gain during pregnancy. Methods: The atherogenic index of plasma (AIP) and oxidative stress status parameters were determinated in 50 healthy and 172 pregnant women with non-complicated pregnancy. Pregnant women were divided in four groups according to body mass index (BMI) values (BMI quartiles). Results: Oxidative stress parameters were significantly lower in the control group compared with all the pregnant women quartiles. Unexpectedly, differences in oxidative stress parameters between BMI quartiles groups were not significant. The antioxidant defence parameters remained quite similar in the different BMI quartiles. Weight gain and paraoxonase-1 (PON1) activities were independently associated with increased AIP while weight gain and triglyceride concentration were found to be significant predictors of PON1 activities. Conclusions: The results of our current study indicate the association of maternal weight gain during pregnancy and altered lipid profile, elevated oxidative stress and changed antioxidative capacity of PON1. Taken together all these facts indicate possible increased risk of cardiovascular disease (CVD) development in later life if the weight gain during pregnancy is excessive.

Oxidative Stress, HDL and Atherosclerosis

Oxidative stress is a result of an imbalanced equilibrium between reactive oxygen species (ROS) generation and their elimination by antioxidants. There is substantial evidence indicating that exacerbated oxidative stress is relevant for the development of atherosclerosis and its associated complications, especially cardiovascular disease (CVD). According to the oxidative modification hypothesis, oxidised low density lipoproteins (LDL) induce atherosclerosis by triggering an inflammatory cascade within the vascular wall. This process can be inhibited or delayed by the antioxidative and antiinflammatory actions of high density lipoproteins (HDL). Clearly, paraoxonase-1 (PON1) is one of the most important contributors to the antioxidative capacity of HDL. Atherogenic dyslipidemia, oxidative stress and inflammatory conditions induce dramatic changes in HDL composition that considerably alters or attenuates HDLs anti-atherogenic effects. Such impairment of HDLs functions provides an important link between oxidative stress and inflammation in the pathogenesis of atherosclerosis. This review summarises and discusses the possible synergistic effects of dyslipidemia, oxidative stress and inflammation in promoting atherosclerosis and its complications, as well as potential benefits of therapeutic modulation of HDLs atheroprotective activity.

LYMPHOCYTE Cu/ZnSOD AND MnSOD GENE EXPRESSION RESPONSES TO INTENSIVE ENDURANCE SOCCER TRAINING

ABSTRACT The purpose of the present study was to examine the effect of physical training on the gene expression levels of Cu/Zn superoxide dismutase (Cu/Zn SOD) and Mn superoxide dismutase (Mn SOD) in young soccer players at the beginning of their professional careers. The non-trained young men underwent a professional soccer training program of 12 weeks. Blood was obtained at two time points: before and after the 12-week endurance soccer training. Plasmatic superoxide dismutase (SOD) activity, concentration of sulfhydryl (SH) groups, superoxide anion (O2.-), malondialdehyde (MDA), and advanced oxidation protein product (AOPP) were determined. Messenger RNA (mRNA) relative levels of SOD isoenzymes were measured in peripheral blood mononuclear cells by Real-time PCR. After 12-week training, the soccer group experienced a significant decrease in plasmatic SOD activity and increase of O2.- concentration. Concentration of SH groups, MDA and AOPP were not affected by physical training, although they showed a trend to increase. Cu/Zn SOD mRNA expression levels were stable during the endurance training period but Mn SOD mRNA levels were significantly higher after the training period. The variation in Mn SOD mRNA levels was dependent on MDA concentration. Negative prediction of MDA concentration on Mn SOD mRNA expression levels remained significant after inclusion of all the other oxidative stress status parameters in a multiple regression model (p = 0.017). Positive prediction of Cu/Zn SOD mRNA levels on plasmatic SOD activity remained significant after inclusion of MDA, log O2.- and AOPP concentrations in a multiple regression model (p = 0.025). Intensive endurance soccer training stimulated a beneficial increase in lymphocyte Mn SOD rather than in Cu/Zn SOD mRNA expression levels. An interaction between the oxidative stress/antioxidative defence status parameters in blood and gene expression levels of Cu/Zn SOD and Mn SOD in PBMCs was also observed.