Israel Medical Association Journal

An arginine-rich apolipoprotein was discovered 50 years ago and became known as apolipoprotein E (ApoE) 10 years later. ApoE is associated with triglyceride-rich lipoproteins and mediates the clearance of these lipoproteins from the plasma. The ApoE-deficient hypercholesterolemic mice are an excellent platform for experimental atherosclerosis because they are similar to human pathology with regard to an atherogenic diet. ApoE is mainly produced in the liver and central nervous system cells. Three alleles determine six ApoE phenotypes with different metabolic effects and plasma cholesterol levels. Type III dysbetalipoproteinemia is associated with wide-spread atherogenesis with a defective ApoE2 resulting in delayed clearance of triglyceride-rich lipoproteins. ApoE4 substantially increases the risk including age of onset, progression, and prognosis of Alzheimer’s disease. Therefore, much effort has been directed to the elucidation of the pathogenic role of ApoE related to amyloid β (Aβ) acquisition in the brain. The ApoE trail passing from an enigmatic protein to a major player in cardiovascular and neurodegenerative disorders is reviewed

Background: Fat tissue mediates the production of inflammatory cytokines and oxidative products, which are key steps in the development of type 2 diabetes and atherosclerosis. Antioxidant-rich diets protect against chronic diseases, but antioxidants may interfere with pro-inflammatory signals.

Objectives: To investigate the effect of the potent tomato-derived antioxidant carotenoid, lycopene, on plasma antioxidants (carotenoids and vitamin E), inflammatory markers (C-reactive protein, interleukin-6, tumor necrosis factor-alpha), and oxidation products (conjugated dienes).

Methods: Eight obese patients (body mass index 37.5 ± 2.5 kg/m²) were compared with a control group of eight lean, age and gender-matched subjects (BMI[1] 21.6 ±  0.6 kg/m²), before and after 4 weeks of lycopene supplementation (tomato-derived Lyc-O-Mato) (30 mg daily).

Results: Plasma carotenoids were significantly reduced in the obese compared to control subjects (0.54 ± 0.06 vs. 0.87 ± 0.08 mg/ml, P < 0.01). CRP[2] levels were significantly higher (6.5 vs. 1.1 mg/L, P = 0.04) in obese vs. controls, as were IL-6[3] and conjugated dienes (3.6 and 7.9-fold, respectively). CRP, IL-6 and conjugated dienes correlated with BMI, while IL-6 and conjugated dienes correlated inversely with carotenoids (P < 0.05). Following lycopene treatment, a significant elevation of plasma carotenoids (1.79 vs. 0.54 ug/ml) and specifically lycopene (1.15 vs 0.23 ug/ml) (P < 0.001) occurred in the treatment vs. placebo group, respectively. Markers of inflammation and oxidation products were not altered by lycopene.
Conclusions: Obese patients showed abnormally higher markers of inflammation and oxidation products and lower plasma carotenoids. The lack of reduction of pro-inflammatory markers could be attributed to the short period of the study and the small number of participants. More studies are needed on the protective qualities of natural antioxidant-rich diets against obesity-related co-morbidities.

Background: Obesity is among the well-established risk factors for cardiovascular morbidity and mortality. However, the exact mechanisms are not well understood. Low concentrations of vitamins (fat soluble antioxidants and B vitamins) are linked to accelerated atherosclerosis through increased oxidative stress and homocysteine.

Objective: To compare plasma antioxidant vitamins (carotenoids and vitamin E), B vitamins (folic acid and B12) and homocysteine – all linked to increased cardiovascular morbidity – between patients with severe obesity and lean control subjects.

Methods: We investigated plasma carotenoids, vitamin E, folic acid, B12, and homocysteine in 25 obese patients and their age-matched controls (body mass index 38 ± 3 vs. 21 ± 2 kg/m²), respectively), related to BMI[1] and plasma insulin.

Results: Patients with obesity had normal B vitamins and a non-significant decrease in plasma homocysteine as compared to controls (9.4 ± 2.6 vs. 11.4 ± 4.8 mmol/L, P = 0.07). There was a significant decrease in both plasma carotenoids and vitamin E (0.69 ± 0.32 vs. 1.25 ± 0.72 and 24 ± 10 vs. 33 ± 14 mg/ml, respectively; P < 0.01). Both vitamins were inversely related to BMI and plasma insulin, which was significantly increased in patients with obesity (22 ± 21 vs. 6 ± 2 mU/ml, P < 0.01).

Conclusions: Obese patients with BMI above 35 kg/m² show low plasma antioxidants (carotenoids and vitamin E). This may result in increased oxidative stress and consequently enhanced atherosclerosis in these patients.

Methods: We attempted to investigate plasma oxidation and plasma and erythrocyte glutathione and glutathione enzymes in 20 patients with NIDDM, compared with euglycemic matched controls. Plasma oxidation was analyzed both basally (without) and as induced by 2,2'-azobis,2-amidopropane hydrochloride measured by the generation of thiobarbituric acid reactive substances and lipid peroxides.

Results: There was a significant increase in oxidation both basally (without) and as induced by AAPH. Plasma glutathione was lowered by 50% (P<0.01) and erythrocyte glutathione peroxidase, glutathione s-transferase and glutathione reductase activities were lower by 30%, 27% and 46%, respectively (P<0.01) in the patients with NIDDM.

Conclusions: Confronted by increased oxidation, patients with NIDDM show an abnormal plasma and erythrocyte antioxidative capacity, which may result in an accelerated rate of complications.

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NIDOM= non-insulin-dependent diabetes mellitus