Oxidative Stress: An Effective Prognostic Tool for an Early Detection of Cardiovascular Disease in Menopausal Women

Background. Menopause, a form of reproductive aging, is marked by many hormonal variations which cause imbalance in the oxidative processes resulting in onset of endothelial dysfunction leading to cardiovascular disease (CVD). We aimed to analyze the effect of oxidative stress in an early detection of CVD in all menopausal women both normolipidemic and hyperlipidemic. Methods and Results. Study included 523 menopausal women (265 CVD and 258 non-CVD). They were screened for lipid profile, serum malondialdehyde (MDA), serum LDL carbonyl protein, and serum superoxide dismutase (SOD). Pearson's correlation was observed between MDA and atherogenic index of plasma (AIP) in both normolipidemic (r = 0.650; p < 0.001) and hyperlipidemic (r = 0.207; p < 0.01) CVD group as compared to non-CVD menopausal women. Significant correlation was also observed between LDL carbonyl content and AIP in normolipidemic (r = 0.650; p < 0.001) and hyperlipidemic (r = 0.248; p < 0.01) CVD menopausal women as compared to non-CVD ones. Conclusion. Strong correlation between atherogenic index of plasma and oxidative stress in CVD menopausal women reveals oxidative stress as an effective prognostic tool for an early detection of cardiovascular risk.

Oxidative stress biomarkers as predictors of cardiovascular disease

Evidence for the role of oxidative stress in the pathogenesis of cardiovascular disease (CVD) is primarily based on experimental and observational human studies. The aim of this review is to examine the observational longitudinal studies that have investigated the relationship between oxidative stress biomarkers and CVD. Fifty-one studies were identified with twenty-six of these measuring oxidized (Ox)-LDL, fifteen assessing myeloperoxidase, seven using lipid peroxidation measures and three quantifying protein oxidation. Results of studies using Ox-LDL have been equivocal with sixteen of the twenty-six studies reporting that this measure is predictive of cardiovascular events. These inconsistent results are not explained by differences in the study populations (primary or secondary CVD) or the type of assay used (auto or monoclonal antibodies). Six of the seven lipid peroxidation, and two of three protein oxidation studies found associations. Twelve of fifteen studies assessing the role of myeloperoxidase reported it to be predictive of CVD. However, issues surrounding the specificity of myeloperoxidase as a marker of oxidative stress and the small number of research groups reporting these results, limit this finding. In summary, the ability of oxidative stress biomarkers to predict CVD has yet to be established. Furthermore, it is important to note that the methods used to assess oxidative stress in these studies are indirect, and the evidence that the various methods actually reflect oxidative stress in vivo is limited.

Metabolic disorders of acute exposure to malathion in adult Wistar rats

Malathion is a widely organphosphorus insecticide used in agriculture, which shows strong insecticidal effects. However, the use of this insecticide leads to disruption in metabolic pathways. The aim of this study is to evaluate the acute effects of malathion on metabolic parameters in Wistar rats. Malathion was administered orally to rats at a dose of 400mg/kg body weight dissolved in corn oil. Glucidic and lipidic status were analyzed in plasma, cholinesterase activities were also determined. Malathion induces a transitory hyperglycaemia which correlated with depletion on glycogen content. Plasma triglycerides and LDL level increased significantly in malathion treated-rats. HDL rate was unchanged and cholesterol plasma content decrease transitory but rapidly reached a normal level. Results of this study indicate, clearly, that malathion in acute exposure leads to a disruption of lipid metabolism with an enhancement in LDL and triglyceride contents and may play an important role in the development of atherosclerosis and cardiovascular disease. Disruption in plasma lipid profile may leads to a kind of insulin resistance which results in hyperglycaemia.

Effect of insulin treatment on plasma oxidized LDL/LDL-cholesterol ratio in type 2 diabetic patients

OBJECTIVE

In type 2 diabetes mellitus, oxidized LDL/LDL-Cholesterol ratio, an accurate estimation of in vivo LDL oxidation, has been reported elevated and associated with macrovascular disease. Because insulin therapy induces significant modification of lipid metabolism, in type 2 diabetes, we evaluated the effect of insulin treatment on oxidized LDL/LDL-C ratio in type 2 diabetic patients and analyzed the results in comparison with the modifications induced by insulin on glycaemia, plasma lipids and LDL receptors.

RESEARCH DESIGN AND METHODS

Plasma oxidized LDL concentrations were measured by sandwich ELISA in 21 type 2 diabetic patients before and 3 months after the introduction of insulin therapy, and in 27 age-matched controls.

RESULTS

Type 2 diabetic patients had, compared to controls, significantly increased oxidized LDL/LDL-C ratio (P<0.0001). Three months after insulin treatment, oxidized LDL/LDL-C ratio was significantly reduced (21.1+/-4.7 vs. 24.0+/-5.8 U/mmol, P<0.01). This reduction was strongly associated, in multivariate analysis, with reduction of LDL(TG/cholesterol ratio) (P=0.008), and to a lesser extent with the decrease of LDL fructosamine (P=0.034), but not with the increase of the number of LDL receptors.

CONCLUSIONS

In the present study we demonstrate for the first time a lowering effect of insulin therapy on oxidized LDL/LDL-C ratio in type 2 diabetic patients. This decrease is mainly associated with the reduction of LDL TG-enrichment, and to a lesser extent with the decrease of LDL glycation, but not with the insulin-induced increase in number of LDL receptors.

Glycaemic control, markers of endothelial cell activation and oxidative stress in children with type 1 diabetes mellitus

BACKGROUND

The aim of this study was to compare the effect of glycaemic control on oxidative stress and biochemical markers of endothelial activation in type 1 diabetic children.

METHODS

Serum total cholesterol, HDL cholesterol, VLDL cholesterol, apolipoprotein A1, apolipoprotein B, HbA(1c), MDA, VEGF, NO, ICAM levels were assessed in 100 children with type 1 DM aged 2-17 years. Study cases were evaluated in three groups in view of their mean HbA(1c) values, as metabolically well-controlled (HbA(1c)< or =8%) and poorly controlled (HbA(1c)>8%) patients with DM and 40 healthy children were included as normal controls.

RESULTS

Levels of MDA, NO, VEGF, ICAM, apolipoprotein A1 and apolipoprotein B in metabolically poorly controlled diabetic patients were significantly higher than control group (P<0.05). In correlation analysis of HbA(1c) to VEGF, no significant correlations were detected in metabolically well-controlled DM, but there were significant correlations between HbA(1c) and NO, MDA, ICAM levels. In correlation analysis of HbA(1c) to VEGF, NO, MDA and ICAM levels, significant correlations were detected in poorly controlled diabetics (P<0.05).

CONCLUSIONS

In the present study, increased levels of MDA, NO, ICAM-1 and VEGF levels showed that especially metabolically poorly controlled DM children are at high risk of atherosclerosis and vascular complications of DM and that there is a significant relationship between HbA(1c) and oxidative stress. It may be appropriate to evaluate levels of VEGF and sICAM-1 as well as markers of oxidative stress in addition to routine laboratory assessments in evaluation of type 1 DM pediatric patients.

Glycemic control, oxidative stress, and lipid profile in children with type 1 diabetes mellitus

BACKGROUND

In diabetes mellitus, persistence of hyperglycemia was reported to cause increased production of oxidative parameters including malondialdehyde (MDA). In the present study, the effect of glycemic control on oxidative stress and the lipid profile of pediatric type 1 diabetes mellitus (DM) patients were investigated.

METHODS

Serum total cholesterol, HDL cholesterol, VLDL cholesterol, apolipoprotein A, apolipoprotein B, lipoprotein a, HbA(1c), and MDA levels were assessed in 96 children with type 1 DM. Study cases were evaluated in two groups in view of their mean HbA(1c) values, as metabolically well controlled (HbA(1c) < or =8%) and poorly controlled (HbA(1c) >8%) patients with DM. Fifty healthy children were included as normal controls.

RESULTS

Total cholesterol, LDL cholesterol, apolipoprotein A, apolipoprotein B, and MDA levels of total diabetic patients were significantly (p<0.05) higher than those of the control group. Serum MDA levels and MDA/LDL cholesterol index were significantly increased in metabolically poorly controlled in relation to metabolically well-controlled DM patients and were similar in metabolically well-controlled DM patients with relation to control group and in metabolically poorly controlled patients with relation to control group.

CONCLUSIONS

In the present study, increased levels of MDA, MDA/LDL index, and dyslipoproteinemia showed that especially metabolically poorly controlled DM children are at high risk of atherosclerosis and vascular complications of DM and that there is a significant relationship between the lipid profile and oxidative stress. Thus, it may be appropriate to evaluate MDA in addition to routine laboratory assessments in evaluation of type 1 DM pediatric patients.

Comparison of a high-carbohydrate and a high-monounsaturated fat, olive oil-rich diet on the susceptibility of LDL to oxidative modification in subjects with Type 2 diabetes mellitus

AIMS

To compare the effects of a high-carbohydrate (CHO) diet and a high-monounsaturated fatty acid (MUFA) diet on LDL oxidative resistance in free-living individuals with Type 2 diabetes mellitus.

METHODS

Twenty-two men and women out-patients with Type 2 diabetes, with mean age 61 years and in fair metabolic control (HbA1c<8.0%), were enrolled at a university hospital lipid clinic in a randomized, crossover feeding trial comparing two isocaloric diets for 6 weeks each: CHO (fat, 28% energy) and MUFA (fat, 40% energy) based on virgin olive oil. Outcome measurements were changes in LDL susceptibility to oxidation, body weight, glycaemic control, and lipoprotein profiles.

RESULTS

Planned and observed diets were well matched. Participants preferred the MUFA diet over the CHO diet. The lag time of conjugated diene formation during Cu2+-induced LDL oxidation was similar after the CHO and MUFA diets (36.4 +/- 12.2 min and 36.0 +/- 13.7 min, respectively). Body weight, glycaemic control, total triglycerides, and total, LDL- and HDL-cholesterol levels also were similar after the two diets. Compared with the CHO diet, the MUFA diet lowered VLDL-cholesterol by 35% (P=0.023) and VLDL triglyceride by 16% (P=0.016).

CONCLUSIONS

Natural food-based high-CHO and high-MUFA diets have similar effects on LDL oxidative resistance and metabolic control in subjects with Type 2 diabetes. A MUFA diet is a good alternative to high-CHO diets for nutrition therapy of diabetes because it also has a beneficial effect on the lipid profile and superior patient acceptance.

A simple method to assess the oxidative susceptibility of low density lipoproteins

BACKGROUND: Oxidative modification of low density lipoproteins (LDL) is recognized as one of the major processes involved in atherogenesis. The in vitro standardized measurement of LDL oxidative susceptibility could thus be of clinical significance. The aim of the present study was to establish a method which would allow the evaluation of oxidative susceptibility of LDL in the general clinical laboratory. RESULTS: LDL was isolated from human plasma by selective precipitation with amphipathic polymers. The ability of LDL to form peroxides was assessed by measuring thiobarbituric acid reactive substances (TBARS) after incubation with Cu2+ and H2O2. Reaction kinetics showed a three-phase pattern (latency, propagation and decomposition phases) which allowed us to select 150 min as the time point to stop the incubation by cooling and EDTA addition. The mixture Cu2+/H2O2 yielded more lipoperoxides than each one on its own at the same time end-point. Induced peroxidation was measured in normal subjects and in type 2 diabetic patients. In the control group, results were 21.7 +/- 1.5 nmol MDA/mg LDL protein, while in the diabetic group results were significantly increased (39.0 +/- 3.0 nmol MDA/mg LDL protein; p < 0.001). CONCLUSION: a simple and useful method is presented for the routine determination of LDL susceptibility to peroxidation in a clinical laboratory.

Therapeutic modulation of low-density lipoprotein size

Small, dense LDL particles have been linked to atherosclerosis, often in a cluster of risk factors and affecting approximately 20% of adults. Over the past year, studies confirmed that small dense LDL is an autosomal dominant trait, influenced mainly by hypertriglyceridaemia and obesity, insulin resistance and diabetes mellitus and some incompletely investigated genetic loci. Compositional and functional differences have been observed in small LDL. Evidence is emerging that lifestyle as well as pharmacological intervention can modulate LDL size, but there is no proof yet that this is of clinical benefit.