Improved method for the immunological detection of malondialdehyde-modified low-density lipoproteins in human serum

Lipid Peroxidation of the Docosahexaenoic Acid/Arachidonic Acid Ratio Relating to the Social Behaviors of Individuals with Autism Spectrum Disorder: The Relationship with Ferroptosis

Polyunsaturated fatty acids (PUFAs) undergo lipid peroxidation and conversion into malondialdehyde (MDA). MDA reacts with acetaldehyde to form malondialdehyde-modified low-density lipoprotein (MDA-LDL). We studied unsettled issues in the association between MDA-LDL and the pathophysiology of ASD in 18 individuals with autism spectrum disorders (ASD) and eight age-matched controls. Social behaviors were assessed using the social responsiveness scale (SRS). To overcome the problem of using small samples, adaptive Lasso was used to enhance the interpretability accuracy, and a coefficient of variation was used for variable selections. Plasma levels of the MDA-LDL levels (91.00 ± 16.70 vs. 74.50 ± 18.88) and the DHA/arachidonic acid (ARA) ratio (0.57 ± 0.16 vs. 0.37 ± 0.07) were significantly higher and the superoxide dismutase levels were significantly lower in the ASD group than those in the control group. Total SRS scores in the ASD group were significantly higher than those in the control group. The unbeneficial DHA/ARA ratio induced ferroptosis via lipid peroxidation. Multiple linear regression analysis and adaptive Lasso revealed an association of the DHA/ARA ratio with total SRS scores and increased MDA-LDL levels in plasma, resulting in neuronal deficiencies. This unbeneficial DHA/ARA-ratio-induced ferroptosis contributes to autistic social behaviors and is available for therapy.

The role of lipid peroxidation in individuals with autism spectrum disorders

The role of malondialdehyde-modified low-density lipoprotein (MDA-LDL), an oxidized LDL, in the pathophysiology of autism spectrum disorder (ASD) is unclear. We studied association between MDA-LDL and behavioral symptoms in 11 individuals with ASD and 7 age -matched normal controls. Behavioral symptoms were assessed using the Aberrant Behavior Checklists (ABC). Because small sample size in this study, three measures were conducted: first, employment of adaptive Lasso for enhancing the accuracy of prediction and interpretability; second, calculation of coefficient of variation for an appropriate selection of plasma variables; and third, selection of good candidates of plasma variables. Plasma levels of MDA-LDL, eicosapentaenoic acid, docosahexaenoic acid (DHA) and DHA/arachidonic acid ratios were significantly higher, while plasma superoxide dismutase (SOD) levels were significantly lower in the ASD group than in the control group. The total ABC scores were significantly higher in the ASD group than in the control group. Multiple linear regression analysis and the adaptive Lasso revealed association of increased plasma DHA levels with the ABC total scores and increased plasma MDA-LDL levels. Such association between DHA and plasma MDA-LDL levels may contribute to behavior in individuals with ASD.

Increase in oxidized low-density lipoprotein level according to hyperglycemia in patients with cardiovascular disease: A study by structure equation modeling

AIMS

Malondialdehyde-modified low-density lipoprotein (MDA-LDL) level has been reported to be strongly associated with the pathogenesis of cardiovascular diseases. We focused on diabetic status and investigated its possible contribution to MDA-LDL level.

METHODS

The study sample consisted of 2705 patients who were admitted to our hospital and underwent cardiac catheterization. Blood samples were obtained to measure the levels of fasting blood sugar (FBS), hemoglobin A1c (HbA1c), insulin, LDL, MDA-LDL and others. Body mass index (BMI) was also used in constructing structural equation modeling and Bayesian estimation.

RESULTS

To explore the factors theoretically associated with MDA-LDL level, we performed structural equation modeling. We generated a path model that revealed that BMI, LDL level and FBS were significantly associated with MDA-LDL level (P < 0.001 for each factor), whereas insulin level and HbA1c level were not significantly associated (P = NS for both factors). Noted above was clearly demonstrated on the image of 2-D contour line by Bayesian structure equation modeling.

CONCLUSIONS

This study clearly showed that hyperglycemia affects MDA-LDL level. An interaction between diabetes and dyslipidemia was shown in terms of activation of lipid oxidation.

Investigation of MDA-LDL (malondialdehyde-modified low-density lipoprotein) as a prognostic marker for coronary artery disease in patients with type 2 diabetes mellitus

BACKGROUND

Although increased circulating levels of malondialdehyde-modified low-density lipoprotein (MDA-LDL) are associated with coronary artery disease (CAD), there is no direct evidence that increased MDA-LDL is a prognostic factor for CAD.

METHODS

Forty-two patients (20 diabetic and 22 non-diabetic patients) who underwent percutaneous coronary intervention (PCI) were enrolled, and their baseline MDA-LDL levels were determined by immunoassay. Follow-up coronary angiography was performed at 2 to 7 months post-PCI. The patients were then divided into 2 groups, with in-stent restenosis (ISR) (n=13) and without ISR (n=29), and the baseline MDA-LDL levels were compared. We also studied 34 diabetics with CAD for up to 57 months until the onset of the next coronary event.

RESULTS

In the diabetic patients, the mean MDA-LDL level was significantly higher in those with ISR than in those without ISR (151+/-61 vs. 90+/-26 U/l, p=0.010). A baseline MDA-LDL value of 110 U/l for differentiating between diabetics with and without ISR was defined as the cut-off value. Kaplan-Meier analysis demonstrated that a circulating MDA-LDL of ≥ 110 U/l correlated significantly with a higher prevalence of cardiac events than MDA-LDL <110 U/l (p=0.032).

CONCLUSIONS

Circulating MDA-LDL is a useful prognostic marker for future cardiac event in diabetic patients with CAD.

Increase in the oxidised low-density lipoprotein level by smoking and the possible inhibitory effect of statin therapy in patients with cardiovascular disease: a retrospective study

OBJECTIVES

Malondialdehyde-modified low-density lipoprotein (MDA-LDL) level is a marker of oxidative stress and is linked to progression of arteriosclerosis; however, the clinical factors affecting the oxidised LDL level have not been elucidated. We investigate various factors to identify correlation with MDA-LDL level in high-risk patients requiring catheter intervention.

SETTING

Secondary care (cardiology), single-centre study.

PARTICIPANTS

600 patients who were admitted to our hospital and underwent cardiac catheterisation.

PRIMARY AND SECONDARY OUTCOME MEASURES

Blood samples were obtained to measure lipid profiles and MDA-LDL level.

RESULTS

With regard to smoking status, MDA-LDL level was significantly higher in ex-smokers/current smokers compared with non-smokers. Of note, there was no improvement of MDA-LDL level even in patients who had quit smoking. Multiple regression analysis showed that MDA-LDL level was positively correlated with LDL-cholesterol (LDL-C) level, Brinkman index and male gender. The correlation between smoking status and either MDA-LDL or LDL-C level was investigated in two groups: namely, patients with and patients without statin treatment. In the non-statin group, MDA-LDL level and MDA-LDL/LDL-C ratio were significantly higher in ex-smokers/current smokers compared with non-smokers, while no significant correlation was observed between smoking status and LDL-C level. In contrast, in the statin group, there were no significant correlations between smoking status and any of the cholesterol parameters.

CONCLUSIONS

We found that MDA-LDL level was affected by multiple factors, such as smoking status, LDL-C level and male gender. The present findings give additional evidence that smoking should be prohibited from a MDA-LDL standpoint. Furthermore, statin therapy might have a beneficial effect on the reduction of MDA-LDL level.

Oxidised LDL/LDL-cholesterol ratio and coronary artery calcification in haemodialysis patients

BACKGROUND AND AIMS

Serum malondialdehyde-modified low-density lipoprotein (MDA-LDL) and MDA-LDL/LDL-cholesterol (LDL-c) ratio are risk factors for arteriosclerosis and cardiovascular disease (CVD). However, no information is available on these parameters or their associations with coronary artery calcification (CAC) in haemodialysis (HD) patients.

METHODS AND RESULTS

Fifty-seven HD patients and 26 control subjects were included in this cross-sectional study. Serum MDA-LDL concentrations and MDA-LDL/LDL-c ratios were examined. HD patients had significantly higher MDA-LDL/LDL-c ratios than the controls (105.1 ± 27.5 vs. 81.4 ± 18.9 mU/mg, P < 0.001); however, there was no significant difference in serum MDA-LDL levels between the 2 groups. CAC scores were examined only in HD patients and their possible associations with the clinical/laboratory data were analysed. Analysis of HD patients showed that MDA-LDL/LDL-c ratio has an association with presence of CVD, CAC score, HD duration, MDA-LDL, or haemoglobin A1C. In addition, the CAC score was positively correlated with serum MDA-LDL level (P = 0.048) and MDA-LDL/LDL-c ratio (P = 0.006). Furthermore, multivariate logistic regression analysis showed that MDA-LDL/LDL-c ratio (β = 0.04, P = 0.003) and HD duration (β = 0.16, P = 0.007) were independently associated with CAC score.

CONCLUSION

The MDA-LDL/LDL-c ratio of HD patients was significantly higher than that of non-HD subjects and was independently associated with the CAC score. Therefore, this ratio could be an important risk factor for CAC in HD patients.

Impact of lipid profile and high blood pressure on endothelial damage

BACKGROUND

Endothelial damage is an early component of atherosclerosis; however, the impact of cardiovascular risk factors on endothelial function is not clearly understood. We investigated the impact of lipid profiles and high blood pressure on damage.

OBJECTIVE

Japanese male outpatients with grade I or II hypertension, along with gender and age-matched normotensive subjects (both n = 25), were enrolled. Subjects with severe cardiovascular risk factors or illness or those taking medications were excluded. Blood was sampled for laboratory analysis and endothelial function was assessed by flow-mediated dilation (FMD).

RESULTS

Total cholesterol to high-density lipoprotein cholesterol ratio (total-C/HDL-C) was inversely correlated with the FMD value and positively correlated with both malondialdehyde-modified low-density lipoprotein and high-sensitivity C-reactive protein values. Stepwise regression analysis revealed total-C/HDL-C and systolic blood pressure were significant determinants of FMD. Hypertensive subjects had lower FMD values and similar lipid profiles to normotensive subjects. Grouping subjects according to total-C/HDL-C levels showed that those with high values had lower FMD values. Hypertensive subjects with low total-C/HDL-C had similar endothelial index values to those in normotensive subjects with high total-C/HDL-C. Logistic regression indicated hypertension and high total-C/HDL-C were significantly associated with low FMD values.

CONCLUSION

Impaired endothelial function was associated with increased total-C/HDL-C values, possibly as the result of increased vascular oxidative stress and inflammation. In the early stages of atherosclerosis, the impact of both total-C/HDL-C and BP may be similar in terms of endothelial damage.

Decreased plasma level of vitamin C in chronic kidney disease: comparison between diabetic and non-diabetic patients

BACKGROUND

A decreased plasma level of vitamin C has been reported to be associated with an increased risk of cardiovascular morbidity and mortality. Here, we sought to determine the vitamin C status of patients with chronic kidney disease and the pathophysiological role of vitamin C in these patients.

METHODS

We studied 58 patients and evaluated the relationship between renal function and plasma vitamin C concentration, as well as the effect of diabetes on this relationship. Endothelium-dependent flow-mediated dilation of brachial artery was measured to assess the endothelial function. Serum malondialdehyde low-density lipoprotein was measured as a marker for oxidative stress.

RESULTS

Plasma vitamin C concentration had a positive linear relationship with eGFR in both diabetic and non-diabetic patients (P = 0.006 and P = 0.004, respectively). When vitamin C concentration and eGFR relationships were compared in the two groups, vitamin C concentration was significantly lower in diabetic patients at every eGFR (P = 0.006). Flow-mediated vasodilatation of the brachial artery was positively correlated with vitamin C concentration in non-diabetic patients (P = 0.047) but not in diabetic patients. There was a negative correlation between serum malondialdehyde low-density lipoprotein and vitamin C concentration in non-diabetic patients (P = 0.044) but not in diabetic patients.

CONCLUSIONS

Renal dysfunction was associated with a decrease in plasma vitamin C level. Moreover, decreased vitamin C may cause endothelial dysfunction via an increase in oxidative stress in non-diabetic chronic kidney disease patients.

Effects of long-term nicorandil administration on endothelial function, inflammation, and oxidative stress in patients without coronary artery disease

Long-term administration of nicorandil has been shown to improve outcomes through cardioprotective effects in patients with coronary artery disease. To identify the mechanisms responsible for these effects, this study examined the impact of long-term nicorandil administration on endothelial function, systemic inflammatory markers, and oxidative stress in patients with cardiovascular risk factors. Fifty-three patients were assigned to receive either nicorandil therapy (15 mg/day; n = 26) (nicorandil group) or usual care (n = 27) (nonnicorandil group). All study participants underwent flow-mediated vasodilatation (FMD) of the brachial artery 1 month before treatment, just before treatment, and at 3, 6, and 12 months following treatment. At identical time points, serum levels of malondialdehyde-modified low-density lipoprotein (MDA-LDL) and high-sensitivity C-reactive protein (hs-CRP) were collected. Compared with the nonnicorandil group, the nicorandil group demonstrated significantly increased FMD at 12 months, a finding not replicated for endothelium-independent vasodilatation with nitroglycerine. Analysis of biochemical markers revealed significantly reduced MAD-LDL levels in the nicorandil group at 12 months, as compared to slightly increased MAD-LDL levels in the nonnicorandil group. Significant reductions in hs-CRP levels were also noted at 6 and 12 months in the nicorandil group, while no change was found in the nonnicorandil group. Results demonstrated that long-term nicorandil therapy is associated with gradual improvements in endothelial function. Our findings also suggest that nicorandil treatment may result in cardiovascular protection through pleiotropic effects including reductions in oxidative injury and systemic inflammation.

Preoperative cerebral hemodynamic impairment and reactive oxygen species produced during carotid endarterectomy correlate with development of postoperative cerebral hyperperfusion

BACKGROUND AND PURPOSE

The purpose of the present study was to determine whether preoperative cerebral hemodynamic impairment and reactive oxygen species produced during carotid endarterectomy (CEA) correlate with development of postoperative cerebral hyperperfusion.

METHODS

Concentrations of malondialdehyde-modified low-density lipoprotein (MDA-LDL), a biochemical marker of oxidative damage, were measured in serum samples obtained from 90 patients undergoing CEA for ipsilateral ICA stenosis (>70%). Serum samples were obtained from a venous catheter inserted into the ipsilateral jugular bulb before clamping of the internal carotid artery (ICA), 10 minutes after clamping of the ICA, and 5 and 20 minutes after declamping of the ICA. Cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) to acetazolamide were also measured using single-photon emission computed-tomography before CEA. In addition, CBF was measured postoperatively.

RESULTS

Hyperperfusion (CBF increase >100% compared with preoperative values) was observed immediately after CEA in 12 patients (13%). Logistic regression analysis demonstrated that reduced preoperative CVR (95% CIs, 1.053 to 1.453; P=0.0097) and an increase in MDA-LDL (calculated as a percentage of the preclamp values) after ICA declamping (95% CIs, 0.862 to 0.980; P=0.0098) were significantly associated with development of postoperative cerebral hyperperfusion among the variables tested. Ten of 11 patients with reduced preoperative CVR and increased MDA-LDL after ICA declamping developed post-CEA hyperperfusion, and 2 of these patients developed cerebral hyperperfusion syndrome.

CONCLUSIONS

Both preoperative cerebral hemodynamic impairment and reactive oxygen species produced during surgery correlate with development of cerebral hyperperfusion after CEA.

Evaluation of oxidative stress and effectiveness of low-dose glucocorticoid therapy on exacerbation of chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and its exacerbation are considered to be related to oxidative stress. We determined the levels of reactive oxygen metabolites (ROM) and a biological antioxidant potential (BAP) in blood before and after the exacerbation.

METHODS

For these determinations, the Free Radical Analytical System 4 was used. Twenty-one male patients were divided into two groups.

RESULTS

Group A patients (n = 11, for whom the disease was end-stage) showed high ROM levels and low BAP levels. Meanwhile, Group B patients (n = 10, for whom the disease was not end-stage but the exacerbation was repeated) exhibited variable ROM levels corresponding to the symptoms. Before the exacerbation, ROM levels increased. After administering high-dose glucocorticoids, the exacerbation disappeared and ROM levels decreased to the baseline. To suppress the relapse, the Group B patients were medicated with low-dose glucocorticoids by inhalation and systemic administration. Then, ROM levels did not increase or the relapse did not occur. BAP levels continued to be low, and were restored after a stable state was obtained.

CONCLUSION

Overproduction of ROM may precede exacerbation of COPD, and the low-dose glucocorticoid therapy may be effective to suppress its overproduction and to preserve COPD in a stable state.

CONCENTRATION OF MALONDIALDEHYDE-MODIFIED LOW-DENSITY LIPOPROTEIN IN THE JUGULAR BULB DURING CAROTID ENDARTERECTOMY CORRELATES WITH DEVELOPMENT OF POSTOPERATIVE COGNITIVE IMPAIRMENT

OBJECTIVE

Approximately 20 to 30% of patients undergoing carotid endarterectomy (CEA) subsequently develop cognitive impairment. The purpose of the present study is to determine whether or not malondialdehyde (MDA)-modified low-density lipoprotein (LDL), a biochemical marker of oxidative damage, concentrations in the jugular bulb during CEA correlates with development of postoperative cognitive impairment.

METHODS

Fifty-five patients undergoing CEA were assessed with a battery of neuropsychological tests before and 1 month after surgery. Serum samples for measurement of MDA-LDL concentration were obtained from a venous catheter inserted into the ipsilateral jugular bulb at the following time points: immediately before clamping of the internal carotid artery (ICA), 10 minutes after clamping of the ICA, and 5 and 20 minutes after declamping of the ICA.

RESULTS

The MDA-LDL concentrations at 5 and 20 minutes after ICA declamping were both significantly higher than concentrations before ICA clamping (P < 0.0001). At the postoperative neuropsychological assessment, six (11%) out of 55 patients showed postoperative cognitive impairment. Logistic regression analysis demonstrated that higher values of MDA-LDL increase (calculated as a percentage of the preclamp values) at either 5 or 20 minutes after ICA declamping were significantly associated with the development of postoperative cognitive impairment (95% confidence interval, 0.787-0.981; P = 0.0209) among the variables tested.

CONCLUSION

MDA-LDL concentration in the jugular bulb during CEA correlates with development of postoperative cognitive impairment.

Beneficial effects of grape seed extract on malondialdehyde-modified LDL

Following consecutive 12-wk administration of tablets containing 0, 200 or 400 mg grape seed extract (calculated as proanthocyanidin) to 61 healthy subjects with LDL cholesterol (LDL-C) levels of 100 to 180 mg/dL, effects of such treatment compared to administration of placebo tablets on malondialdehyde-modified LDL (MDA-LDL), representing one oxidized type of LDL, were investigated by a single blind method. MDA-LDL level in the 200 mg (calculated as proanthocyanidin) group was significantly (p = 0.008) reduced compared to the basal level, 12 wk after the start of administration. In the 400 mg (calculated as proanthocyanidin) group, a significant decrease in MDA-LDL level compared to the basal level was found 6 and 12 wk after the start of administration (6 wk: p = 0.015, 12 wk: p = 0.009). Subjects with high levels of MDA-LDL/ApoB (MDA-LDL/ApoB > or = 100 mU/mL) in the 200 mg group showed significantly (p = 0.011) reduced MDA-LDL levels at 12 wk after the start of administration. In the 400 mg group, significant decreases in MDA-LDL level compared to the basal level were seen 6 and 12 wk after the start of administration (6 wk: p = 0.001, 12 wk: p < 0.001); and at week 6, significantly (p = 0.048) lower values were observed compared to those in patients who took placebo tablets (0 mg proanthocyanidin). In subjects demonstrating the least body weight changes during the test period (less than +/- 1.0 kg) in the 400 mg group, there was an increasing trend (p = 0.088) in adiponectin levels 12 wk after the start of treatment. These results suggested that tablets containing grape seed extract exerted reducing effects on oxidized LDL, and might be useful in preventing lifestyle-related diseases such as arteriosclerosis.

Investigation of oxidative stress and dietary habits in Mongolian people, compared to Japanese people

Background

The average life span of Mongolians is 62 years for males and 69 years for females. This life span is about 16 years shorter than that of Japanese. Mongolian people generally eat meat, fat and diary products but less vegetables or fruit. Thus, we investigated the state of oxidative stress and dietary habits of Mongolians.

Methods

The investigation was performed in Murun city in the northwest area of Mongolia. A total of 164 healthy subjects (24–66 y) were enrolled. As a marker of reactive oxygen species, the levels of reactive oxygen metabolites (ROM) were measured using the d-ROM test. Interviews about dietary habits were performed using the Food Frequency Questionnaire established by the Kagawa Nutrition University.

Results

ROM levels were 429.7 ± 95.2 Carr U for Murun subjects, whereas Japanese people (n = 220, 21–98 y) showed 335.3 ± 59.8 (p < 0.001). The levels of serum malondialdehyde-modified low-density lipoprotein-cholesterol and urinary 8-hydroxydeoxyguanosine were also high. ROM levels correlated with body fat ratio and inversely correlated with handgrip strength. Handgrip strength in the subjects over 45 years decreased more rapidly than that of age-matched Japanese. Murun subjects ate larger amounts of meat, fat, milk and flour and dairy products than Japanese, but less vegetables or fruit. Serum vitamin A and E levels were the same as Japanese references, but vitamin C levels were lower.

Conclusion

Murun subjects may be in high oxidative stress, which may have a relationship with early ageing and several diseases, ultimately resulting in their short life span. In order to increase antioxidant capacity and suppress overproduction of ROM, antioxidant food intake is recommended.